LinuxGuruz
  • Last 5 Forum Topics
    Replies
    Views
    Last post


The Web Only This Site
  • BOOKMARK

  • ADD TO FAVORITES

  • REFERENCES


  • MARC

    Mailing list ARChives
    - Search by -
     Subjects
     Authors
     Bodies





    FOLDOC

    Computing Dictionary




  • Text Link Ads






  • LINUX man pages
  • Linux Man Page Viewer


    The following form allows you to view linux man pages.

    Command:

    gcc

    
    
    

    SYNOPSIS

           gcc [-c|-S|-E] [-std=standard]
               [-g] [-pg] [-Olevel]
               [-Wwarn...] [-pedantic]
               [-Idir...] [-Ldir...]
               [-Dmacro[=defn]...] [-Umacro]
               [-foption...] [-mmachine-option...]
               [-o outfile] [@file] infile...
    
           Only the most useful options are listed here; see below for the
           remainder.  g++ accepts mostly the same options as gcc.
    
    
    

    DESCRIPTION

           When you invoke GCC, it normally does preprocessing, compilation,
           assembly and linking.  The "overall options" allow you to stop this
           process at an intermediate stage.  For example, the -c option says not
           to run the linker.  Then the output consists of object files output by
           the assembler.
    
           Other options are passed on to one stage of processing.  Some options
           control the preprocessor and others the compiler itself.  Yet other
           options control the assembler and linker; most of these are not
           documented here, since you rarely need to use any of them.
    
           Most of the command line options that you can use with GCC are useful
           for C programs; when an option is only useful with another language
           (usually C++), the explanation says so explicitly.  If the description
           for a particular option does not mention a source language, you can use
           that option with all supported languages.
    
           The gcc program accepts options and file names as operands.  Many
           options have multi-letter names; therefore multiple single-letter
           options may not be grouped: -dv is very different from -d -v.
    
           You can mix options and other arguments.  For the most part, the order
           you use doesn't matter.  Order does matter when you use several options
           of the same kind; for example, if you specify -L more than once, the
           directories are searched in the order specified.  Also, the placement
           of the -l option is significant.
    
           Many options have long names starting with -f or with -W---for example,
           -fmove-loop-invariants, -Wformat and so on.  Most of these have both
           positive and negative forms; the negative form of -ffoo would be
           -fno-foo.  This manual documents only one of these two forms, whichever
           one is not the default.
    
    
    

    OPTIONS

       Option Summary
           Here is a summary of all the options, grouped by type.  Explanations
           are in the following sections.
    
           Overall Options
               -ffriend-injection -fno-elide-constructors -fno-enforce-eh-specs
               -ffor-scope  -fno-for-scope  -fno-gnu-keywords
               -fno-implicit-templates -fno-implicit-inline-templates
               -fno-implement-inlines  -fms-extensions -fno-nonansi-builtins
               -fno-operator-names -fno-optional-diags  -fpermissive -frepo
               -fno-rtti  -fstats  -ftemplate-depth-n -fno-threadsafe-statics
               -fuse-cxa-atexit  -fno-weak  -nostdinc++ -fno-default-inline
               -fvisibility-inlines-hidden -fvisibility-ms-compat -Wabi
               -Wctor-dtor-privacy -Wnon-virtual-dtor  -Wreorder -Weffc++
               -Wstrict-null-sentinel -Wno-non-template-friend  -Wold-style-cast
               -Woverloaded-virtual  -Wno-pmf-conversions -Wsign-promo
    
           Objective-C and Objective-C++ Language Options
               -fconstant-string-class=class-name -fgnu-runtime  -fnext-runtime
               -fno-nil-receivers -fobjc-call-cxx-cdtors -fobjc-direct-dispatch
               -fobjc-exceptions -fobjc-gc -freplace-objc-classes -fzero-link
               -gen-decls -Wassign-intercept -Wno-protocol  -Wselector
               -Wstrict-selector-match -Wundeclared-selector
    
           Language Independent Options
               -fmessage-length=n -fdiagnostics-show-location=[once|every-line]
               -fdiagnostics-show-option
    
           Warning Options
               -fsyntax-only  -pedantic  -pedantic-errors -w  -Wextra  -Wall
               -Waddress  -Waggregate-return  -Warray-bounds -Wno-attributes
               -Wno-builtin-macro-redefined -Wc++-compat -Wc++0x-compat
               -Wcast-align  -Wcast-qual -Wchar-subscripts -Wclobbered  -Wcomment
               -Wconversion  -Wcoverage-mismatch  -Wno-deprecated
               -Wno-deprecated-declarations -Wdisabled-optimization
               -Wno-div-by-zero -Wempty-body  -Wenum-compare -Wno-endif-labels
               -Werror  -Werror=* -Wfatal-errors  -Wfloat-equal  -Wformat
               -Wformat=2 -Wno-format-contains-nul -Wno-format-extra-args
               -Wformat-nonliteral -Wformat-security  -Wformat-y2k
               -Wframe-larger-than=len -Wignored-qualifiers -Wimplicit
               -Wimplicit-function-declaration  -Wimplicit-int -Winit-self
               -Winline -Wno-int-to-pointer-cast -Wno-invalid-offsetof
               -Winvalid-pch -Wlarger-than=len  -Wunsafe-loop-optimizations
               -Wlogical-op -Wlong-long -Wmain  -Wmissing-braces
               -Wmissing-field-initializers -Wmissing-format-attribute
               -Wmissing-include-dirs -Wmissing-noreturn  -Wno-mudflap
               -Wno-multichar  -Wnonnull  -Wno-overflow -Woverlength-strings
               -Wpacked  -Wpacked-bitfield-compat  -Wpadded -Wparentheses
               -Wpedantic-ms-format -Wno-pedantic-ms-format -Wpointer-arith
               -Wno-pointer-to-int-cast -Wredundant-decls -Wreturn-type
               -Wsequence-point  -Wshadow -Wsign-compare  -Wsign-conversion
               -Wstack-protector -Wstrict-aliasing -Wstrict-aliasing=n
               -Wstrict-overflow -Wstrict-overflow=n -Wswitch  -Wswitch-default
               -Wswitch-enum -Wsync-nand -Wsystem-headers  -Wtrigraphs
               -Wtype-limits  -Wundef  -Wuninitialized -Wunknown-pragmas
               -Wno-pragmas -Wunreachable-code -Wunused  -Wunused-function
               -Wunused-label  -Wunused-parameter -Wunused-value
               -fdump-unnumbered-links -fdump-translation-unit[-n]
               -fdump-class-hierarchy[-n] -fdump-ipa-all -fdump-ipa-cgraph
               -fdump-ipa-inline -fdump-statistics -fdump-tree-all
               -fdump-tree-original[-n] -fdump-tree-optimized[-n] -fdump-tree-cfg
               -fdump-tree-vcg -fdump-tree-alias -fdump-tree-ch
               -fdump-tree-ssa[-n] -fdump-tree-pre[-n] -fdump-tree-ccp[-n]
               -fdump-tree-dce[-n] -fdump-tree-gimple[-raw]
               -fdump-tree-mudflap[-n] -fdump-tree-dom[-n] -fdump-tree-dse[-n]
               -fdump-tree-phiopt[-n] -fdump-tree-forwprop[-n]
               -fdump-tree-copyrename[-n] -fdump-tree-nrv -fdump-tree-vect
               -fdump-tree-sink -fdump-tree-sra[-n] -fdump-tree-fre[-n]
               -fdump-tree-vrp[-n] -ftree-vectorizer-verbose=n
               -fdump-tree-storeccp[-n] -fdump-final-insns=file
               -fcompare-debug[=opts]  -fcompare-debug-second
               -feliminate-dwarf2-dups -feliminate-unused-debug-types
               -feliminate-unused-debug-symbols -femit-class-debug-always
               -fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report
               -fprofile-arcs -frandom-seed=string -fsched-verbose=n
               -fsel-sched-verbose -fsel-sched-dump-cfg
               -fsel-sched-pipelining-verbose -ftest-coverage  -ftime-report
               -fvar-tracking -fvar-tracking-assignments
               -fvar-tracking-assignments-toggle -g  -glevel  -gtoggle  -gcoff
               -gdwarf-version -ggdb  -gstabs  -gstabs+  -gstrict-dwarf
               -gno-strict-dwarf -gvms  -gxcoff  -gxcoff+ -fno-merge-debug-strings
               -fno-dwarf2-cfi-asm -fdebug-prefix-map=old=new
               -femit-struct-debug-baseonly -femit-struct-debug-reduced
               -femit-struct-debug-detailed[=spec-list] -p  -pg
               -print-file-name=library  -print-libgcc-file-name
               -print-multi-directory  -print-multi-lib  -print-multi-os-directory
               -print-prog-name=program  -print-search-dirs  -Q -print-sysroot
               -print-sysroot-headers-suffix -save-temps  -time[=file]
    
           Optimization Options
               -falign-functions[=n] -falign-jumps[=n] -falign-labels[=n]
               -falign-loops[=n] -fassociative-math -fauto-inc-dec
               -fbranch-probabilities -fbranch-target-load-optimize
               -fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves
               -fcheck-data-deps -fconserve-stack -fcprop-registers -fcrossjumping
               -fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules
               -fcx-limited-range -fdata-sections -fdce -fdce -fdelayed-branch
               -fdelete-null-pointer-checks -fdse -fdse -fearly-inlining
               -fexpensive-optimizations -ffast-math -ffinite-math-only
               -ffloat-store -fforward-propagate -ffunction-sections -fgcse
               -fgcse-after-reload -fgcse-las -fgcse-lm -fgcse-sm -fif-conversion
               -fif-conversion2 -findirect-inlining -finline-functions
               -finline-functions-called-once -finline-limit=n
               -finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg
               -fipa-pta -fipa-pure-const -fipa-reference -fipa-struct-reorg
               -fipa-type-escape -fira-algorithm=algorithm -fira-region=region
               -fira-coalesce -fno-ira-share-save-slots -fno-ira-share-spill-slots
               -fira-verbose=n -fivopts -fkeep-inline-functions
               -fkeep-static-consts -floop-block -floop-interchange
               -frerun-cse-after-loop -freschedule-modulo-scheduled-loops
               -frounding-math -frtl-abstract-sequences -fsched2-use-superblocks
               -fsched2-use-traces -fsched-spec-load -fsched-spec-load-dangerous
               -fsched-stalled-insns-dep[=n] -fsched-stalled-insns[=n]
               -fschedule-insns -fschedule-insns2 -fsection-anchors -fsee
               -fselective-scheduling -fselective-scheduling2
               -fsel-sched-pipelining -fsel-sched-pipelining-outer-loops
               -fsignaling-nans -fsingle-precision-constant
               -fsplit-ivs-in-unroller -fsplit-wide-types -fstack-protector
               -fstack-protector-all -fstrict-aliasing -fstrict-overflow
               -fthread-jumps -ftracer -ftree-builtin-call-dce -ftree-ccp
               -ftree-ch -ftree-coalesce-inline-vars -ftree-coalesce-vars
               -ftree-copy-prop -ftree-copyrename -ftree-dce -ftree-dominator-opts
               -ftree-dse -ftree-fre -ftree-loop-im -ftree-loop-distribution
               -ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize
               -ftree-parallelize-loops=n -ftree-pre -ftree-reassoc -ftree-sink
               -ftree-sra -ftree-switch-conversion -ftree-ter
               -ftree-vect-loop-version -ftree-vectorize -ftree-vrp
               -funit-at-a-time -funroll-all-loops -funroll-loops
               -funsafe-loop-optimizations -funsafe-math-optimizations
               -funswitch-loops -fvariable-expansion-in-unroller -fvect-cost-model
               -fvpt -fweb -fwhole-program --param name=value -O  -O0  -O1  -O2
               -O3  -Os
    
           Preprocessor Options
               -Aquestion=answer -A-question[=answer] -C  -dD  -dI  -dM  -dN
               -Dmacro[=defn]  -E  -H -idirafter dir -include file  -imacros file
               -iprefix file  -iwithprefix dir -iwithprefixbefore dir  -isystem
               dir -imultilib dir -isysroot dir -M  -MM  -MF  -MG  -MP  -MQ  -MT
               -nostdinc -P  -fworking-directory  -remap -trigraphs  -undef
               -Umacro  -Wp,option -Xpreprocessor option
    
           Assembler Option
               -Wa,option  -Xassembler option
    
           Linker Options
               object-file-name  -llibrary -nostartfiles  -nodefaultlibs
               -nostdlib -pie -rdynamic -s  -static  -static-libgcc  -shared
               -shared-libgcc  -symbolic -T script  -Wl,option  -Xlinker option -u
               symbol
    
           Directory Options
               -Bprefix  -Idir  -iquotedir  -Ldir -specs=file  -I- --sysroot=dir
    
           Target Options
               -V version  -b machine
    
           Machine Dependent Options
               ARC Options -EB  -EL -mmangle-cpu  -mcpu=cpu  -mtext=text-section
               -mdata=data-section  -mrodata=readonly-data-section
    
               ARM Options -mapcs-frame  -mno-apcs-frame -mabi=name
               -mno-tablejump  -mtiny-stack  -mint8
    
               Blackfin Options -mcpu=cpu[-sirevision] -msim
               -momit-leaf-frame-pointer  -mno-omit-leaf-frame-pointer
               -mspecld-anomaly  -mno-specld-anomaly  -mcsync-anomaly
               -mno-csync-anomaly -mlow-64k -mno-low64k  -mstack-check-l1
               -mid-shared-library -mno-id-shared-library  -mshared-library-id=n
               -mleaf-id-shared-library  -mno-leaf-id-shared-library -msep-data
               -mno-sep-data  -mlong-calls  -mno-long-calls -mfast-fp -minline-plt
               -mmulticore  -mcorea  -mcoreb  -msdram -micplb
    
               CRIS Options -mcpu=cpu  -march=cpu  -mtune=cpu -mmax-stack-frame=n
               -melinux-stacksize=n -metrax4  -metrax100  -mpdebug  -mcc-init
               -mno-side-effects -mstack-align  -mdata-align  -mconst-align
               -m32-bit  -m16-bit  -m8-bit  -mno-prologue-epilogue  -mno-gotplt
               -melf  -maout  -melinux  -mlinux  -sim  -sim2 -mmul-bug-workaround
               -mno-mul-bug-workaround
    
               CRX Options -mmac -mpush-args
    
               Darwin Options -all_load  -allowable_client  -arch
               -arch_errors_fatal -arch_only  -bind_at_load  -bundle
               -bundle_loader -client_name  -compatibility_version
               -current_version -dead_strip -dependency-file  -dylib_file
               -dylinker_install_name -dynamic  -dynamiclib
               -exported_symbols_list -filelist  -flat_namespace
               -force_cpusubtype_ALL -force_flat_namespace
               -headerpad_max_install_names -iframework -image_base  -init
               -install_name  -keep_private_externs -multi_module
               -multiply_defined  -multiply_defined_unused -noall_load
               -no_dead_strip_inits_and_terms -nofixprebinding -nomultidefs
               -noprebind  -noseglinkedit -pagezero_size  -prebind
               -prebind_all_twolevel_modules -private_bundle  -read_only_relocs
               -sectalign -sectobjectsymbols  -whyload  -seg1addr -sectcreate
               -sectobjectsymbols  -sectorder -segaddr -segs_read_only_addr
               -segs_read_write_addr -seg_addr_table  -seg_addr_table_filename
               -seglinkedit -segprot  -segs_read_only_addr  -segs_read_write_addr
               -single_module  -static  -sub_library  -sub_umbrella
               -twolevel_namespace  -umbrella  -undefined -unexported_symbols_list
               -weak_reference_mismatches -whatsloaded -F -gused -gfull
               -mmacosx-version-min=version -mkernel -mone-byte-bool
    
               DEC Alpha Options -mno-fp-regs  -msoft-float  -malpha-as  -mgas
               -mieee  -mieee-with-inexact  -mieee-conformant -mfp-trap-mode=mode
               -mfp-rounding-mode=mode -mtrap-precision=mode  -mbuild-constants
               -mcpu=cpu-type  -mtune=cpu-type -mbwx  -mmax  -mfix  -mcix
               -mfloat-vax  -mfloat-ieee -mexplicit-relocs  -msmall-data
               -mlarge-data -msmall-text  -mlarge-text -mmemory-latency=time
    
               DEC Alpha/VMS Options -mvms-return-codes
    
               FR30 Options -msmall-model -mno-lsim
               H8/300 Options -mrelax  -mh  -ms  -mn  -mint32  -malign-300
    
               HPPA Options -march=architecture-type -mbig-switch
               -mdisable-fpregs  -mdisable-indexing -mfast-indirect-calls  -mgas
               -mgnu-ld   -mhp-ld -mfixed-range=register-range -mjump-in-delay
               -mlinker-opt -mlong-calls -mlong-load-store  -mno-big-switch
               -mno-disable-fpregs -mno-disable-indexing  -mno-fast-indirect-calls
               -mno-gas -mno-jump-in-delay  -mno-long-load-store
               -mno-portable-runtime  -mno-soft-float -mno-space-regs
               -msoft-float  -mpa-risc-1-0 -mpa-risc-1-1  -mpa-risc-2-0
               -mportable-runtime -mschedule=cpu-type  -mspace-regs  -msio  -mwsio
               -munix=unix-std  -nolibdld  -static  -threads
    
               i386 and x86-64 Options -mtune=cpu-type  -march=cpu-type
               -mfpmath=unit -masm=dialect  -mno-fancy-math-387 -mno-fp-ret-in-387
               -msoft-float -mno-wide-multiply  -mrtd  -malign-double
               -mpreferred-stack-boundary=num -mincoming-stack-boundary=num -mcld
               -mcx16 -msahf -mmovbe -mcrc32 -mrecip -mmmx  -msse  -msse2 -msse3
               -mssse3 -msse4.1 -msse4.2 -msse4 -mavx -maes -mpclmul -mfsgsbase
               -mrdrnd -mf16c -mfused-madd -msse4a -m3dnow -mpopcnt -mabm -mbmi
               -mtbm -mfma4 -mxop -mlwp -mthreads  -mno-align-stringops
               -minline-all-stringops -minline-stringops-dynamically
               -mstringop-strategy=alg -mpush-args  -maccumulate-outgoing-args
               -m128bit-long-double -m96bit-long-double  -mregparm=num
               -msseregparm -mveclibabi=type -mpc32 -mpc64 -mpc80 -mstackrealign
               -momit-leaf-frame-pointer  -mno-red-zone -mno-tls-direct-seg-refs
               -mcmodel=code-model -m32  -m64 -mlarge-data-threshold=num -msse2avx
    
               i386 and x86-64 Windows Options -mconsole -mcygwin -mno-cygwin
               -mdll -mnop-fun-dllimport -mthread -mwin32 -mwindows
    
               IA-64 Options -mbig-endian  -mlittle-endian  -mgnu-as  -mgnu-ld
               -mno-pic -mvolatile-asm-stop  -mregister-names  -mno-sdata
               -mconstant-gp  -mauto-pic  -minline-float-divide-min-latency
               -minline-float-divide-max-throughput
               -minline-int-divide-min-latency -minline-int-divide-max-throughput
               -minline-sqrt-min-latency -minline-sqrt-max-throughput
               -mno-dwarf2-asm -mearly-stop-bits -mfixed-range=register-range
               -mtls-size=tls-size -mtune=cpu-type -mt -pthread -milp32 -mlp64
               -mno-sched-br-data-spec -msched-ar-data-spec
               -mno-sched-control-spec -msched-br-in-data-spec
               -msched-ar-in-data-spec -msched-in-control-spec -msched-ldc
               -mno-sched-control-ldc -mno-sched-spec-verbose
               -mno-sched-prefer-non-data-spec-insns
               -mno-sched-prefer-non-control-spec-insns
               -mno-sched-count-spec-in-critical-path
    
               M32R/D Options -m32r2 -m32rx -m32r -mdebug -malign-loops
               -mno-align-loops -missue-rate=number -mbranch-cost=number
               -mmodel=code-size-model-type -msdata=sdata-type -mno-flush-func
               -mflush-func=name -mno-flush-trap -mflush-trap=number -G num
    
    
               MCore Options -mhardlit  -mno-hardlit  -mdiv  -mno-div
               -mrelax-immediates -mno-relax-immediates  -mwide-bitfields
               -mno-wide-bitfields -m4byte-functions  -mno-4byte-functions
               -mcallgraph-data -mno-callgraph-data  -mslow-bytes  -mno-slow-bytes
               -mno-lsim -mlittle-endian  -mbig-endian  -m210  -m340
               -mstack-increment
    
               MIPS Options -EL  -EB  -march=arch  -mtune=arch -mips1  -mips2
               -mips3  -mips4  -mips32  -mips32r2 -mips64  -mips64r2 -mips16
               -mno-mips16  -mflip-mips16 -minterlink-mips16
               -mno-interlink-mips16 -mabi=abi  -mabicalls  -mno-abicalls -mshared
               -mno-shared  -mplt  -mno-plt  -mxgot  -mno-xgot -mgp32  -mgp64
               -mfp32  -mfp64  -mhard-float  -msoft-float -msingle-float
               -mdouble-float  -mdsp  -mno-dsp  -mdspr2  -mno-dspr2 -mfpu=fpu-type
               -msmartmips  -mno-smartmips -mpaired-single  -mno-paired-single
               -mdmx  -mno-mdmx -mips3d  -mno-mips3d  -mmt  -mno-mt  -mllsc
               -mno-llsc -mlong64  -mlong32  -msym32  -mno-sym32 -Gnum
               -mlocal-sdata  -mno-local-sdata -mextern-sdata  -mno-extern-sdata
               -mgpopt  -mno-gopt -membedded-data  -mno-embedded-data
               -muninit-const-in-rodata  -mno-uninit-const-in-rodata
               -mcode-readable=setting -msplit-addresses  -mno-split-addresses
               -mexplicit-relocs  -mno-explicit-relocs -mcheck-zero-division
               -mno-check-zero-division -mdivide-traps  -mdivide-breaks -mmemcpy
               -mno-memcpy  -mlong-calls  -mno-long-calls -mmad  -mno-mad
               -mfused-madd  -mno-fused-madd  -nocpp -mfix-r4000  -mno-fix-r4000
               -mfix-r4400  -mno-fix-r4400 -mfix-r10000 -mno-fix-r10000
               -mfix-vr4120  -mno-fix-vr4120 -mfix-vr4130  -mno-fix-vr4130
               -mfix-sb1  -mno-fix-sb1 -mflush-func=func  -mno-flush-func
               -mbranch-cost=num  -mbranch-likely  -mno-branch-likely
               -mfp-exceptions -mno-fp-exceptions -mvr4130-align -mno-vr4130-align
    
               MMIX Options -mlibfuncs  -mno-libfuncs  -mepsilon  -mno-epsilon
               -mabi=gnu -mabi=mmixware  -mzero-extend  -mknuthdiv
               -mtoplevel-symbols -melf  -mbranch-predict  -mno-branch-predict
               -mbase-addresses -mno-base-addresses  -msingle-exit
               -mno-single-exit
    
               MN10300 Options -mmult-bug  -mno-mult-bug -mam33  -mno-am33
               -mam33-2  -mno-am33-2 -mreturn-pointer-on-d0 -mno-crt0  -mrelax
    
               PDP-11 Options -mfpu  -msoft-float  -mac0  -mno-ac0  -m40  -m45
               -m10 -mbcopy  -mbcopy-builtin  -mint32  -mno-int16 -mint16
               -mno-int32  -mfloat32  -mno-float64 -mfloat64  -mno-float32
               -mabshi  -mno-abshi -mbranch-expensive  -mbranch-cheap -msplit
               -mno-split  -munix-asm  -mdec-asm
    
               picoChip Options -mae=ae_type -mvliw-lookahead=N
               -msymbol-as-address -mno-inefficient-warnings
    
               PowerPC Options See RS/6000 and PowerPC Options.
    
               -mstrict-align  -mno-strict-align  -mrelocatable -mno-relocatable
               -mrelocatable-lib  -mno-relocatable-lib -mtoc  -mno-toc  -mlittle
               -mlittle-endian  -mbig  -mbig-endian -mdynamic-no-pic  -maltivec
               -mswdiv -mprioritize-restricted-insns=priority
               -msched-costly-dep=dependence_type -minsert-sched-nops=scheme
               -mcall-sysv  -mcall-netbsd -maix-struct-return
               -msvr4-struct-return -mabi=abi-type -msecure-plt -mbss-plt -misel
               -mno-isel -misel=yes  -misel=no -mspe -mno-spe -mspe=yes  -mspe=no
               -mpaired -mgen-cell-microcode -mwarn-cell-microcode -mvrsave
               -mno-vrsave -mmulhw -mno-mulhw -mdlmzb -mno-dlmzb -mfloat-gprs=yes
               -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double -mprototype
               -mno-prototype -msim  -mmvme  -mads  -myellowknife  -memb  -msdata
               -msdata=opt  -mvxworks  -G num  -pthread
    
               S/390 and zSeries Options -mtune=cpu-type  -march=cpu-type
               -mhard-float  -msoft-float  -mhard-dfp -mno-hard-dfp
               -mlong-double-64 -mlong-double-128 -mbackchain  -mno-backchain
               -mpacked-stack  -mno-packed-stack -msmall-exec  -mno-small-exec
               -mmvcle -mno-mvcle -m64  -m31  -mdebug  -mno-debug  -mesa  -mzarch
               -mtpf-trace -mno-tpf-trace  -mfused-madd  -mno-fused-madd
               -mwarn-framesize  -mwarn-dynamicstack  -mstack-size -mstack-guard
               -mhotpatch=halfwords,halfwords
    
               Score Options -meb -mel -mnhwloop -muls -mmac -mscore5 -mscore5u
               -mscore7 -mscore7d
    
               SH Options -m1  -m2  -m2e  -m3  -m3e -m4-nofpu  -m4-single-only
               -m4-single  -m4 -m4a-nofpu -m4a-single-only -m4a-single -m4a -m4al
               -m5-64media  -m5-64media-nofpu -m5-32media  -m5-32media-nofpu
               -m5-compact  -m5-compact-nofpu -mb  -ml  -mdalign  -mrelax
               -mbigtable  -mfmovd  -mhitachi -mrenesas -mno-renesas -mnomacsave
               -mieee  -mbitops  -misize  -minline-ic_invalidate -mpadstruct
               -mspace -mprefergot  -musermode -multcost=number -mdiv=strategy
               -mdivsi3_libfunc=name -mfixed-range=register-range -madjust-unroll
               -mindexed-addressing -mgettrcost=number -mpt-fixed
               -minvalid-symbols
    
               SPARC Options -mcpu=cpu-type -mtune=cpu-type -mcmodel=code-model
               -m32  -m64  -mapp-regs  -mno-app-regs -mfaster-structs
               -mno-faster-structs -mfpu  -mno-fpu  -mhard-float  -msoft-float
               -mhard-quad-float  -msoft-quad-float -mimpure-text
               -mno-impure-text  -mlittle-endian -mstack-bias  -mno-stack-bias
               -munaligned-doubles  -mno-unaligned-doubles -mv8plus  -mno-v8plus
               -mvis  -mno-vis -threads -pthreads -pthread
    
               SPU Options -mwarn-reloc -merror-reloc -msafe-dma -munsafe-dma
               -mbranch-hints -msmall-mem -mlarge-mem -mstdmain
               -mfixed-range=register-range
    
               System V Options -Qy  -Qn  -YP,paths  -Ym,dir
    
               V850 Options -mlong-calls  -mno-long-calls  -mep  -mno-ep
               -mserialize-volatile  -mno-serialize-volatile
               -mtext-section-literals  -mno-text-section-literals -mtarget-align
               -mno-target-align -mlongcalls  -mno-longcalls
    
               zSeries Options See S/390 and zSeries Options.
    
           Code Generation Options
               -fcall-saved-reg  -fcall-used-reg -ffixed-reg  -fexceptions
               -fnon-call-exceptions  -funwind-tables -fasynchronous-unwind-tables
               -finhibit-size-directive  -finstrument-functions
               -finstrument-functions-exclude-function-list=sym,sym,...
               -finstrument-functions-exclude-file-list=file,file,...  -fno-common
               -fno-ident -fpcc-struct-return  -fpic  -fPIC -fpie -fPIE
               -fno-jump-tables -frecord-gcc-switches -freg-struct-return
               -fshort-enums -fshort-double  -fshort-wchar -fverbose-asm
               -fpack-struct[=n]  -fstack-check -fstack-limit-register=reg
               -fstack-limit-symbol=sym -fno-stack-limit  -fargument-alias
               -fargument-noalias -fargument-noalias-global
               -fargument-noalias-anything -fleading-underscore  -ftls-model=model
               -ftrapv  -fwrapv  -fbounds-check -fvisibility
    
       Options Controlling the Kind of Output
           Compilation can involve up to four stages: preprocessing, compilation
           proper, assembly and linking, always in that order.  GCC is capable of
           preprocessing and compiling several files either into several assembler
           input files, or into one assembler input file; then each assembler
           input file produces an object file, and linking combines all the object
           files (those newly compiled, and those specified as input) into an
           executable file.
    
           For any given input file, the file name suffix determines what kind of
           compilation is done:
    
           file.c
               C source code which must be preprocessed.
    
           file.i
               C source code which should not be preprocessed.
    
           file.ii
               C++ source code which should not be preprocessed.
    
           file.m
               Objective-C source code.  Note that you must link with the libobjc
               library to make an Objective-C program work.
    
           file.mi
               Objective-C source code which should not be preprocessed.
    
           file.mm
           file.M
               Objective-C++ source code.  Note that you must link with the
    
           file.CPP
           file.c++
           file.C
               C++ source code which must be preprocessed.  Note that in .cxx, the
               last two letters must both be literally x.  Likewise, .C refers to
               a literal capital C.
    
           file.mm
           file.M
               Objective-C++ source code which must be preprocessed.
    
           file.mii
               Objective-C++ source code which should not be preprocessed.
    
           file.hh
           file.H
           file.hp
           file.hxx
           file.hpp
           file.HPP
           file.h++
           file.tcc
               C++ header file to be turned into a precompiled header.
    
           file.f
           file.for
           file.ftn
               Fixed form Fortran source code which should not be preprocessed.
    
           file.F
           file.FOR
           file.fpp
           file.FPP
           file.FTN
               Fixed form Fortran source code which must be preprocessed (with the
               traditional preprocessor).
    
           file.f90
           file.f95
           file.f03
           file.f08
               Free form Fortran source code which should not be preprocessed.
    
           file.F90
           file.F95
           file.F03
           file.F08
               Free form Fortran source code which must be preprocessed (with the
               traditional preprocessor).
    
           file.ads
               Ada source code file which contains a library unit declaration (a
               Assembler code which must be preprocessed.
    
           other
               An object file to be fed straight into linking.  Any file name with
               no recognized suffix is treated this way.
    
           You can specify the input language explicitly with the -x option:
    
           -x language
               Specify explicitly the language for the following input files
               (rather than letting the compiler choose a default based on the
               file name suffix).  This option applies to all following input
               files until the next -x option.  Possible values for language are:
    
                       c  c-header  c-cpp-output
                       c++  c++-header  c++-cpp-output
                       objective-c  objective-c-header  objective-c-cpp-output
                       objective-c++ objective-c++-header objective-c++-cpp-output
                       assembler  assembler-with-cpp
                       ada
                       f77  f77-cpp-input f95  f95-cpp-input
                       java
    
           -x none
               Turn off any specification of a language, so that subsequent files
               are handled according to their file name suffixes (as they are if
               -x has not been used at all).
    
           -pass-exit-codes
               Normally the gcc program will exit with the code of 1 if any phase
               of the compiler returns a non-success return code.  If you specify
               -pass-exit-codes, the gcc program will instead return with
               numerically highest error produced by any phase that returned an
               error indication.  The C, C++, and Fortran frontends return 4, if
               an internal compiler error is encountered.
    
           If you only want some of the stages of compilation, you can use -x (or
           filename suffixes) to tell gcc where to start, and one of the options
           -c, -S, or -E to say where gcc is to stop.  Note that some combinations
           (for example, -x cpp-output -E) instruct gcc to do nothing at all.
    
           -c  Compile or assemble the source files, but do not link.  The linking
               stage simply is not done.  The ultimate output is in the form of an
               object file for each source file.
    
               By default, the object file name for a source file is made by
               replacing the suffix .c, .i, .s, etc., with .o.
    
               Unrecognized input files, not requiring compilation or assembly,
               are ignored.
    
           -S  Stop after the stage of compilation proper; do not assemble.  The
           -o file
               Place output in file file.  This applies regardless to whatever
               sort of output is being produced, whether it be an executable file,
               an object file, an assembler file or preprocessed C code.
    
               If -o is not specified, the default is to put an executable file in
               a.out, the object file for source.suffix in source.o, its assembler
               file in source.s, a precompiled header file in source.suffix.gch,
               and all preprocessed C source on standard output.
    
           -v  Print (on standard error output) the commands executed to run the
               stages of compilation.  Also print the version number of the
               compiler driver program and of the preprocessor and the compiler
               proper.
    
           -###
               Like -v except the commands are not executed and all command
               arguments are quoted.  This is useful for shell scripts to capture
               the driver-generated command lines.
    
           -pipe
               Use pipes rather than temporary files for communication between the
               various stages of compilation.  This fails to work on some systems
               where the assembler is unable to read from a pipe; but the GNU
               assembler has no trouble.
    
           -combine
               If you are compiling multiple source files, this option tells the
               driver to pass all the source files to the compiler at once (for
               those languages for which the compiler can handle this).  This will
               allow intermodule analysis (IMA) to be performed by the compiler.
               Currently the only language for which this is supported is C.  If
               you pass source files for multiple languages to the driver, using
               this option, the driver will invoke the compiler(s) that support
               IMA once each, passing each compiler all the source files
               appropriate for it.  For those languages that do not support IMA
               this option will be ignored, and the compiler will be invoked once
               for each source file in that language.  If you use this option in
               conjunction with -save-temps, the compiler will generate multiple
               pre-processed files (one for each source file), but only one
               (combined) .o or .s file.
    
           --help
               Print (on the standard output) a description of the command line
               options understood by gcc.  If the -v option is also specified then
               --help will also be passed on to the various processes invoked by
               gcc, so that they can display the command line options they accept.
               If the -Wextra option has also been specified (prior to the --help
               option), then command line options which have no documentation
               associated with them will also be displayed.
    
           --target-help
                   This will display all of the options controlling warning
                   messages produced by the compiler.
    
               target
                   This will display target-specific options.  Unlike the
                   --target-help option however, target-specific options of the
                   linker and assembler will not be displayed.  This is because
                   those tools do not currently support the extended --help=
                   syntax.
    
               params
                   This will display the values recognized by the --param option.
    
               language
                   This will display the options supported for language, where
                   language is the name of one of the languages supported in this
                   version of GCC.
    
               common
                   This will display the options that are common to all languages.
    
               These are the supported qualifiers:
    
               undocumented
                   Display only those options which are undocumented.
    
               joined
                   Display options which take an argument that appears after an
                   equal sign in the same continuous piece of text, such as:
                   --help=target.
    
               separate
                   Display options which take an argument that appears as a
                   separate word following the original option, such as: -o
                   output-file.
    
               Thus for example to display all the undocumented target-specific
               switches supported by the compiler the following can be used:
    
                       --help=target,undocumented
    
               The sense of a qualifier can be inverted by prefixing it with the ^
               character, so for example to display all binary warning options
               (i.e., ones that are either on or off and that do not take an
               argument), which have a description the following can be used:
    
                       --help=warnings,^joined,^undocumented
    
               The argument to --help= should not consist solely of inverted
               qualifiers.
    
               Combining several classes is possible, although this usually
               as to whether the option is enabled, disabled or set to a specific
               value (assuming that the compiler knows this at the point where the
               --help= option is used).
    
               Here is a truncated example from the ARM port of gcc:
    
                         % gcc -Q -mabi=2 --help=target -c
                         The following options are target specific:
                         -mabi=                                2
                         -mabort-on-noreturn                   [disabled]
                         -mapcs                                [disabled]
    
               The output is sensitive to the effects of previous command line
               options, so for example it is possible to find out which
               optimizations are enabled at -O2 by using:
    
                       -Q -O2 --help=optimizers
    
               Alternatively you can discover which binary optimizations are
               enabled by -O3 by using:
    
                       gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts
                       gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts
                       diff /tmp/O2-opts /tmp/O3-opts | grep enabled
    
           --version
               Display the version number and copyrights of the invoked GCC.
    
           -wrapper
               Invoke all subcommands under a wrapper program. It takes a single
               comma separated list as an argument, which will be used to invoke
               the wrapper:
    
                       gcc -c t.c -wrapper gdb,--args
    
               This will invoke all subprograms of gcc under "gdb --args", thus
               cc1 invocation will be "gdb --args cc1 ...".
    
           @file
               Read command-line options from file.  The options read are inserted
               in place of the original @file option.  If file does not exist, or
               cannot be read, then the option will be treated literally, and not
               removed.
    
               Options in file are separated by whitespace.  A whitespace
               character may be included in an option by surrounding the entire
               option in either single or double quotes.  Any character (including
               a backslash) may be included by prefixing the character to be
               included with a backslash.  The file may itself contain additional
               @file options; any such options will be processed recursively.
    
       Compiling C++ Programs
    
           When you compile C++ programs, you may specify many of the same
           command-line options that you use for compiling programs in any
           language; or command-line options meaningful for C and related
           languages; or options that are meaningful only for C++ programs.
    
       Options Controlling C Dialect
           The following options control the dialect of C (or languages derived
           from C, such as C++, Objective-C and Objective-C++) that the compiler
           accepts:
    
           -ansi
               In C mode, this is equivalent to -std=c89. In C++ mode, it is
               equivalent to -std=c++98.
    
               This turns off certain features of GCC that are incompatible with
               ISO C90 (when compiling C code), or of standard C++ (when compiling
               C++ code), such as the "asm" and "typeof" keywords, and predefined
               macros such as "unix" and "vax" that identify the type of system
               you are using.  It also enables the undesirable and rarely used ISO
               trigraph feature.  For the C compiler, it disables recognition of
               C++ style // comments as well as the "inline" keyword.
    
               The alternate keywords "__asm__", "__extension__", "__inline__" and
               "__typeof__" continue to work despite -ansi.  You would not want to
               use them in an ISO C program, of course, but it is useful to put
               them in header files that might be included in compilations done
               with -ansi.  Alternate predefined macros such as "__unix__" and
               "__vax__" are also available, with or without -ansi.
    
               The -ansi option does not cause non-ISO programs to be rejected
               gratuitously.  For that, -pedantic is required in addition to
               -ansi.
    
               The macro "__STRICT_ANSI__" is predefined when the -ansi option is
               used.  Some header files may notice this macro and refrain from
               declaring certain functions or defining certain macros that the ISO
               standard doesn't call for; this is to avoid interfering with any
               programs that might use these names for other things.
    
               Functions that would normally be built in but do not have semantics
               defined by ISO C (such as "alloca" and "ffs") are not built-in
               functions when -ansi is used.
    
           -std=
               Determine the language standard.   This option is currently only
               supported when compiling C or C++.
    
               The compiler can accept several base standards, such as c89 or
               c++98, and GNU dialects of those standards, such as gnu89 or
               gnu++98.  By specifying a base standard, the compiler will accept
               all programs following that standard and those using GNU extensions
    
               c89
               iso9899:1990
                   Support all ISO C90 programs (certain GNU extensions that
                   conflict with ISO C90 are disabled). Same as -ansi for C code.
    
               iso9899:199409
                   ISO C90 as modified in amendment 1.
    
               c99
               c9x
               iso9899:1999
               iso9899:199x
                   ISO C99.  Note that this standard is not yet fully supported;
                   see <http://gcc.gnu.org/gcc-4.4/c99status.html> for more
                   information.  The names c9x and iso9899:199x are deprecated.
    
               gnu89
                   GNU dialect of ISO C90 (including some C99 features). This is
                   the default for C code.
    
               gnu99
               gnu9x
                   GNU dialect of ISO C99.  When ISO C99 is fully implemented in
                   GCC, this will become the default.  The name gnu9x is
                   deprecated.
    
               c++98
                   The 1998 ISO C++ standard plus amendments. Same as -ansi for
                   C++ code.
    
               gnu++98
                   GNU dialect of -std=c++98.  This is the default for C++ code.
    
               c++0x
                   The working draft of the upcoming ISO C++0x standard. This
                   option enables experimental features that are likely to be
                   included in C++0x. The working draft is constantly changing,
                   and any feature that is enabled by this flag may be removed
                   from future versions of GCC if it is not part of the C++0x
                   standard.
    
               gnu++0x
                   GNU dialect of -std=c++0x. This option enables experimental
                   features that may be removed in future versions of GCC.
    
           -fgnu89-inline
               The option -fgnu89-inline tells GCC to use the traditional GNU
               semantics for "inline" functions when in C99 mode.
                 This option is accepted and ignored by GCC versions 4.1.3 up to
               but not including 4.3.  In GCC versions 4.3 and later it changes
               the behavior of GCC in C99 mode.  Using this option is roughly
               functions declared and/or defined in a translation unit, including
               those in header files.  This option is silently ignored in any
               language other than C.
    
               Besides declarations, the file indicates, in comments, the origin
               of each declaration (source file and line), whether the declaration
               was implicit, prototyped or unprototyped (I, N for new or O for
               old, respectively, in the first character after the line number and
               the colon), and whether it came from a declaration or a definition
               (C or F, respectively, in the following character).  In the case of
               function definitions, a K&R-style list of arguments followed by
               their declarations is also provided, inside comments, after the
               declaration.
    
           -fno-asm
               Do not recognize "asm", "inline" or "typeof" as a keyword, so that
               code can use these words as identifiers.  You can use the keywords
               "__asm__", "__inline__" and "__typeof__" instead.  -ansi implies
               -fno-asm.
    
               In C++, this switch only affects the "typeof" keyword, since "asm"
               and "inline" are standard keywords.  You may want to use the
               -fno-gnu-keywords flag instead, which has the same effect.  In C99
               mode (-std=c99 or -std=gnu99), this switch only affects the "asm"
               and "typeof" keywords, since "inline" is a standard keyword in ISO
               C99.
    
           -fno-builtin
           -fno-builtin-function
               Don't recognize built-in functions that do not begin with
               __builtin_ as prefix.
    
               GCC normally generates special code to handle certain built-in
               functions more efficiently; for instance, calls to "alloca" may
               become single instructions that adjust the stack directly, and
               calls to "memcpy" may become inline copy loops.  The resulting code
               is often both smaller and faster, but since the function calls no
               longer appear as such, you cannot set a breakpoint on those calls,
               nor can you change the behavior of the functions by linking with a
               different library.  In addition, when a function is recognized as a
               built-in function, GCC may use information about that function to
               warn about problems with calls to that function, or to generate
               more efficient code, even if the resulting code still contains
               calls to that function.  For example, warnings are given with
               -Wformat for bad calls to "printf", when "printf" is built in, and
               "strlen" is known not to modify global memory.
    
               With the -fno-builtin-function option only the built-in function
               function is disabled.  function must not begin with __builtin_.  If
               a function is named that is not built-in in this version of GCC,
               this option is ignored.  There is no corresponding
               -fbuiltin-function option; if you wish to enable built-in functions
               Assert that compilation takes place in a freestanding environment.
               This implies -fno-builtin.  A freestanding environment is one in
               which the standard library may not exist, and program startup may
               not necessarily be at "main".  The most obvious example is an OS
               kernel.  This is equivalent to -fno-hosted.
    
           -fopenmp
               Enable handling of OpenMP directives "#pragma omp" in C/C++ and
               "!$omp" in Fortran.  When -fopenmp is specified, the compiler
               generates parallel code according to the OpenMP Application Program
               Interface v2.5 <http://www.openmp.org/>.  This option implies
               -pthread, and thus is only supported on targets that have support
               for -pthread.
    
           -fms-extensions
               Accept some non-standard constructs used in Microsoft header files.
    
               Some cases of unnamed fields in structures and unions are only
               accepted with this option.
    
           -trigraphs
               Support ISO C trigraphs.  The -ansi option (and -std options for
               strict ISO C conformance) implies -trigraphs.
    
           -no-integrated-cpp
               Performs a compilation in two passes: preprocessing and compiling.
               This option allows a user supplied "cc1", "cc1plus", or "cc1obj"
               via the -B option.  The user supplied compilation step can then add
               in an additional preprocessing step after normal preprocessing but
               before compiling.  The default is to use the integrated cpp
               (internal cpp)
    
               The semantics of this option will change if "cc1", "cc1plus", and
               "cc1obj" are merged.
    
           -traditional
           -traditional-cpp
               Formerly, these options caused GCC to attempt to emulate a pre-
               standard C compiler.  They are now only supported with the -E
               switch.  The preprocessor continues to support a pre-standard mode.
               See the GNU CPP manual for details.
    
           -fcond-mismatch
               Allow conditional expressions with mismatched types in the second
               and third arguments.  The value of such an expression is void.
               This option is not supported for C++.
    
           -flax-vector-conversions
               Allow implicit conversions between vectors with differing numbers
               of elements and/or incompatible element types.  This option should
               not be used for new code.
    
               The type "char" is always a distinct type from each of "signed
               char" or "unsigned char", even though its behavior is always just
               like one of those two.
    
           -fsigned-char
               Let the type "char" be signed, like "signed char".
    
               Note that this is equivalent to -fno-unsigned-char, which is the
               negative form of -funsigned-char.  Likewise, the option
               -fno-signed-char is equivalent to -funsigned-char.
    
           -fsigned-bitfields
           -funsigned-bitfields
           -fno-signed-bitfields
           -fno-unsigned-bitfields
               These options control whether a bit-field is signed or unsigned,
               when the declaration does not use either "signed" or "unsigned".
               By default, such a bit-field is signed, because this is consistent:
               the basic integer types such as "int" are signed types.
    
       Options Controlling C++ Dialect
           This section describes the command-line options that are only
           meaningful for C++ programs; but you can also use most of the GNU
           compiler options regardless of what language your program is in.  For
           example, you might compile a file "firstClass.C" like this:
    
                   g++ -g -frepo -O -c firstClass.C
    
           In this example, only -frepo is an option meant only for C++ programs;
           you can use the other options with any language supported by GCC.
    
           Here is a list of options that are only for compiling C++ programs:
    
           -fabi-version=n
               Use version n of the C++ ABI.  Version 2 is the version of the C++
               ABI that first appeared in G++ 3.4.  Version 1 is the version of
               the C++ ABI that first appeared in G++ 3.2.  Version 0 will always
               be the version that conforms most closely to the C++ ABI
               specification.  Therefore, the ABI obtained using version 0 will
               change as ABI bugs are fixed.
    
               The default is version 2.
    
           -fno-access-control
               Turn off all access checking.  This switch is mainly useful for
               working around bugs in the access control code.
    
           -fcheck-new
               Check that the pointer returned by "operator new" is non-null
               before attempting to modify the storage allocated.  This check is
               normally unnecessary because the C++ standard specifies that
               "operator new" will only return 0 if it is declared tthhrrooww(()), in
               has been added for putting variables into BSS without making them
               common.
    
           -fno-deduce-init-list
               Disable deduction of a template type parameter as
               std::initializer_list from a brace-enclosed initializer list, i.e.
    
                       template <class T> auto forward(T t) -> decltype (realfn (t))
                       {
                         return realfn (t);
                       }
    
                       void f()
                       {
                         forward({1,2}); // call forward<std::initializer_list<int>>
                       }
    
               This option is present because this deduction is an extension to
               the current specification in the C++0x working draft, and there was
               some concern about potential overload resolution problems.
    
           -ffriend-injection
               Inject friend functions into the enclosing namespace, so that they
               are visible outside the scope of the class in which they are
               declared.  Friend functions were documented to work this way in the
               old Annotated C++ Reference Manual, and versions of G++ before 4.1
               always worked that way.  However, in ISO C++ a friend function
               which is not declared in an enclosing scope can only be found using
               argument dependent lookup.  This option causes friends to be
               injected as they were in earlier releases.
    
               This option is for compatibility, and may be removed in a future
               release of G++.
    
           -fno-elide-constructors
               The C++ standard allows an implementation to omit creating a
               temporary which is only used to initialize another object of the
               same type.  Specifying this option disables that optimization, and
               forces G++ to call the copy constructor in all cases.
    
           -fno-enforce-eh-specs
               Don't generate code to check for violation of exception
               specifications at runtime.  This option violates the C++ standard,
               but may be useful for reducing code size in production builds, much
               like defining NDEBUG.  This does not give user code permission to
               throw exceptions in violation of the exception specifications; the
               compiler will still optimize based on the specifications, so
               throwing an unexpected exception will result in undefined behavior.
    
           -ffor-scope
           -fno-for-scope
               If -ffor-scope is specified, the scope of variables declared in a
    
           -fno-implicit-templates
               Never emit code for non-inline templates which are instantiated
               implicitly (i.e. by use); only emit code for explicit
               instantiations.
    
           -fno-implicit-inline-templates
               Don't emit code for implicit instantiations of inline templates,
               either.  The default is to handle inlines differently so that
               compiles with and without optimization will need the same set of
               explicit instantiations.
    
           -fno-implement-inlines
               To save space, do not emit out-of-line copies of inline functions
               controlled by #pragma implementation.  This will cause linker
               errors if these functions are not inlined everywhere they are
               called.
    
           -fms-extensions
               Disable pedantic warnings about constructs used in MFC, such as
               implicit int and getting a pointer to member function via non-
               standard syntax.
    
           -fno-nonansi-builtins
               Disable built-in declarations of functions that are not mandated by
               ANSI/ISO C.  These include "ffs", "alloca", "_exit", "index",
               "bzero", "conjf", and other related functions.
    
           -fno-operator-names
               Do not treat the operator name keywords "and", "bitand", "bitor",
               "compl", "not", "or" and "xor" as synonyms as keywords.
    
           -fno-optional-diags
               Disable diagnostics that the standard says a compiler does not need
               to issue.  Currently, the only such diagnostic issued by G++ is the
               one for a name having multiple meanings within a class.
    
           -fpermissive
               Downgrade some diagnostics about nonconformant code from errors to
               warnings.  Thus, using -fpermissive will allow some nonconforming
               code to compile.
    
           -frepo
               Enable automatic template instantiation at link time.  This option
               also implies -fno-implicit-templates.
    
           -fno-rtti
               Disable generation of information about every class with virtual
               functions for use by the C++ runtime type identification features
               (dynamic_cast and typeid).  If you don't use those parts of the
               language, you can save some space by using this flag.  Note that
               exception handling uses the same information, but it will generate
               the enumerators).  This assumption may not be valid if the program
               uses a cast to convert an arbitrary integer value to the
               enumeration type.
    
           -ftemplate-depth-n
               Set the maximum instantiation depth for template classes to n.  A
               limit on the template instantiation depth is needed to detect
               endless recursions during template class instantiation.  ANSI/ISO
               C++ conforming programs must not rely on a maximum depth greater
               than 17.
    
           -fno-threadsafe-statics
               Do not emit the extra code to use the routines specified in the C++
               ABI for thread-safe initialization of local statics.  You can use
               this option to reduce code size slightly in code that doesn't need
               to be thread-safe.
    
           -fuse-cxa-atexit
               Register destructors for objects with static storage duration with
               the "__cxa_atexit" function rather than the "atexit" function.
               This option is required for fully standards-compliant handling of
               static destructors, but will only work if your C library supports
               "__cxa_atexit".
    
           -fno-use-cxa-get-exception-ptr
               Don't use the "__cxa_get_exception_ptr" runtime routine.  This will
               cause "std::uncaught_exception" to be incorrect, but is necessary
               if the runtime routine is not available.
    
           -fvisibility-inlines-hidden
               This switch declares that the user does not attempt to compare
               pointers to inline methods where the addresses of the two functions
               were taken in different shared objects.
    
               The effect of this is that GCC may, effectively, mark inline
               methods with "__attribute__ ((visibility ("hidden")))" so that they
               do not appear in the export table of a DSO and do not require a PLT
               indirection when used within the DSO.  Enabling this option can
               have a dramatic effect on load and link times of a DSO as it
               massively reduces the size of the dynamic export table when the
               library makes heavy use of templates.
    
               The behavior of this switch is not quite the same as marking the
               methods as hidden directly, because it does not affect static
               variables local to the function or cause the compiler to deduce
               that the function is defined in only one shared object.
    
               You may mark a method as having a visibility explicitly to negate
               the effect of the switch for that method.  For example, if you do
               want to compare pointers to a particular inline method, you might
               mark it as having default visibility.  Marking the enclosing class
               with explicit visibility will have no effect.
               2.  Types, but not their members, are not hidden by default.
    
               3.  The One Definition Rule is relaxed for types without explicit
                   visibility specifications which are defined in more than one
                   different shared object: those declarations are permitted if
                   they would have been permitted when this option was not used.
    
               In new code it is better to use -fvisibility=hidden and export
               those classes which are intended to be externally visible.
               Unfortunately it is possible for code to rely, perhaps
               accidentally, on the Visual Studio behavior.
    
               Among the consequences of these changes are that static data
               members of the same type with the same name but defined in
               different shared objects will be different, so changing one will
               not change the other; and that pointers to function members defined
               in different shared objects may not compare equal.  When this flag
               is given, it is a violation of the ODR to define types with the
               same name differently.
    
           -fno-weak
               Do not use weak symbol support, even if it is provided by the
               linker.  By default, G++ will use weak symbols if they are
               available.  This option exists only for testing, and should not be
               used by end-users; it will result in inferior code and has no
               benefits.  This option may be removed in a future release of G++.
    
           -nostdinc++
               Do not search for header files in the standard directories specific
               to C++, but do still search the other standard directories.  (This
               option is used when building the C++ library.)
    
           In addition, these optimization, warning, and code generation options
           have meanings only for C++ programs:
    
           -fno-default-inline
               Do not assume inline for functions defined inside a class scope.
                 Note that these functions will have linkage like inline
               functions; they just won't be inlined by default.
    
           -Wabi (C, Objective-C, C++ and Objective-C++ only)
               Warn when G++ generates code that is probably not compatible with
               the vendor-neutral C++ ABI.  Although an effort has been made to
               warn about all such cases, there are probably some cases that are
               not warned about, even though G++ is generating incompatible code.
               There may also be cases where warnings are emitted even though the
               code that is generated will be compatible.
    
               You should rewrite your code to avoid these warnings if you are
               concerned about the fact that code generated by G++ may not be
               binary compatible with code generated by other compilers.
    
    
               ?   Incorrect handling of tail-padding for virtual bases.  G++ does
                   not use tail padding when laying out virtual bases.  For
                   example:
    
                           struct A { virtual void f(); char c1; };
                           struct B { B(); char c2; };
                           struct C : public A, public virtual B {};
    
                   In this case, G++ will not place "B" into the tail-padding for
                   "A"; other compilers will.  You can avoid this problem by
                   explicitly padding "A" so that its size is a multiple of its
                   alignment (ignoring virtual base classes); that will cause G++
                   and other compilers to layout "C" identically.
    
               ?   Incorrect handling of bit-fields with declared widths greater
                   than that of their underlying types, when the bit-fields appear
                   in a union.  For example:
    
                           union U { int i : 4096; };
    
                   Assuming that an "int" does not have 4096 bits, G++ will make
                   the union too small by the number of bits in an "int".
    
               ?   Empty classes can be placed at incorrect offsets.  For example:
    
                           struct A {};
    
                           struct B {
                             A a;
                             virtual void f ();
                           };
    
                           struct C : public B, public A {};
    
                   G++ will place the "A" base class of "C" at a nonzero offset;
                   it should be placed at offset zero.  G++ mistakenly believes
                   that the "A" data member of "B" is already at offset zero.
    
               ?   Names of template functions whose types involve "typename" or
                   template template parameters can be mangled incorrectly.
    
                           template <typename Q>
                           void f(typename Q::X) {}
    
                           template <template <typename> class Q>
                           void f(typename Q<int>::X) {}
    
                   Instantiations of these templates may be mangled incorrectly.
    
               It also warns psABI related changes.  The known psABI changes at
               this point include:
               nor public static member functions.
    
           -Wnon-virtual-dtor (C++ and Objective-C++ only)
               Warn when a class has virtual functions and accessible non-virtual
               destructor, in which case it would be possible but unsafe to delete
               an instance of a derived class through a pointer to the base class.
               This warning is also enabled if -Weffc++ is specified.
    
           -Wreorder (C++ and Objective-C++ only)
               Warn when the order of member initializers given in the code does
               not match the order in which they must be executed.  For instance:
    
                       struct A {
                         int i;
                         int j;
                         A(): j (0), i (1) { }
                       };
    
               The compiler will rearrange the member initializers for i and j to
               match the declaration order of the members, emitting a warning to
               that effect.  This warning is enabled by -Wall.
    
           The following -W... options are not affected by -Wall.
    
           -Weffc++ (C++ and Objective-C++ only)
               Warn about violations of the following style guidelines from Scott
               Meyers' Effective C++ book:
    
               ?   Item 11:  Define a copy constructor and an assignment operator
                   for classes with dynamically allocated memory.
    
               ?   Item 12:  Prefer initialization to assignment in constructors.
    
               ?   Item 14:  Make destructors virtual in base classes.
    
               ?   Item 15:  Have "operator=" return a reference to *this.
    
               ?   Item 23:  Don't try to return a reference when you must return
                   an object.
    
               Also warn about violations of the following style guidelines from
               Scott Meyers' More Effective C++ book:
    
               ?   Item 6:  Distinguish between prefix and postfix forms of
                   increment and decrement operators.
    
               ?   Item 7:  Never overload "&&", "||", or ",".
    
               When selecting this option, be aware that the standard library
               headers do not obey all of these guidelines; use grep -v to filter
               out those warnings.
    
               implemented explicit specification, unqualified-ids could be
               interpreted as a particular specialization of a templatized
               function.  Because this non-conforming behavior is no longer the
               default behavior for G++, -Wnon-template-friend allows the compiler
               to check existing code for potential trouble spots and is on by
               default.  This new compiler behavior can be turned off with
               -Wno-non-template-friend which keeps the conformant compiler code
               but disables the helpful warning.
    
           -Wold-style-cast (C++ and Objective-C++ only)
               Warn if an old-style (C-style) cast to a non-void type is used
               within a C++ program.  The new-style casts (dynamic_cast,
               static_cast, reinterpret_cast, and const_cast) are less vulnerable
               to unintended effects and much easier to search for.
    
           -Woverloaded-virtual (C++ and Objective-C++ only)
               Warn when a function declaration hides virtual functions from a
               base class.  For example, in:
    
                       struct A {
                         virtual void f();
                       };
    
                       struct B: public A {
                         void f(int);
                       };
    
               the "A" class version of "f" is hidden in "B", and code like:
    
                       B* b;
                       b->f();
    
               will fail to compile.
    
           -Wno-pmf-conversions (C++ and Objective-C++ only)
               Disable the diagnostic for converting a bound pointer to member
               function to a plain pointer.
    
           -Wsign-promo (C++ and Objective-C++ only)
               Warn when overload resolution chooses a promotion from unsigned or
               enumerated type to a signed type, over a conversion to an unsigned
               type of the same size.  Previous versions of G++ would try to
               preserve unsignedness, but the standard mandates the current
               behavior.
    
                       struct A {
                         operator int ();
                         A& operator = (int);
                       };
    
                       main ()
                       {
    
           example, you might compile a file "some_class.m" like this:
    
                   gcc -g -fgnu-runtime -O -c some_class.m
    
           In this example, -fgnu-runtime is an option meant only for Objective-C
           and Objective-C++ programs; you can use the other options with any
           language supported by GCC.
    
           Note that since Objective-C is an extension of the C language,
           Objective-C compilations may also use options specific to the C front-
           end (e.g., -Wtraditional).  Similarly, Objective-C++ compilations may
           use C++-specific options (e.g., -Wabi).
    
           Here is a list of options that are only for compiling Objective-C and
           Objective-C++ programs:
    
           -fconstant-string-class=class-name
               Use class-name as the name of the class to instantiate for each
               literal string specified with the syntax "@"..."".  The default
               class name is "NXConstantString" if the GNU runtime is being used,
               and "NSConstantString" if the NeXT runtime is being used (see
               below).  The -fconstant-cfstrings option, if also present, will
               override the -fconstant-string-class setting and cause "@"...""
               literals to be laid out as constant CoreFoundation strings.
    
           -fgnu-runtime
               Generate object code compatible with the standard GNU Objective-C
               runtime.  This is the default for most types of systems.
    
           -fnext-runtime
               Generate output compatible with the NeXT runtime.  This is the
               default for NeXT-based systems, including Darwin and Mac OS X.  The
               macro "__NEXT_RUNTIME__" is predefined if (and only if) this option
               is used.
    
           -fno-nil-receivers
               Assume that all Objective-C message dispatches (e.g., "[receiver
               message:arg]") in this translation unit ensure that the receiver is
               not "nil".  This allows for more efficient entry points in the
               runtime to be used.  Currently, this option is only available in
               conjunction with the NeXT runtime on Mac OS X 10.3 and later.
    
           -fobjc-call-cxx-cdtors
               For each Objective-C class, check if any of its instance variables
               is a C++ object with a non-trivial default constructor.  If so,
               synthesize a special "- (id) .cxx_construct" instance method that
               will run non-trivial default constructors on any such instance
               variables, in order, and then return "self".  Similarly, check if
               any instance variable is a C++ object with a non-trivial
               destructor, and if so, synthesize a special "- (void)
               .cxx_destruct" method that will run all such default destructors,
               in reverse order.
    
           -fobjc-direct-dispatch
               Allow fast jumps to the message dispatcher.  On Darwin this is
               accomplished via the comm page.
    
           -fobjc-exceptions
               Enable syntactic support for structured exception handling in
               Objective-C, similar to what is offered by C++ and Java.  This
               option is unavailable in conjunction with the NeXT runtime on Mac
               OS X 10.2 and earlier.
    
                         @try {
                           ...
                              @throw expr;
                           ...
                         }
                         @catch (AnObjCClass *exc) {
                           ...
                             @throw expr;
                           ...
                             @throw;
                           ...
                         }
                         @catch (AnotherClass *exc) {
                           ...
                         }
                         @catch (id allOthers) {
                           ...
                         }
                         @finally {
                           ...
                             @throw expr;
                           ...
                         }
    
               The @throw statement may appear anywhere in an Objective-C or
               Objective-C++ program; when used inside of a @catch block, the
               @throw may appear without an argument (as shown above), in which
               case the object caught by the @catch will be rethrown.
    
               Note that only (pointers to) Objective-C objects may be thrown and
               caught using this scheme.  When an object is thrown, it will be
               caught by the nearest @catch clause capable of handling objects of
               that type, analogously to how "catch" blocks work in C++ and Java.
               A "@catch(id ...)" clause (as shown above) may also be provided to
               catch any and all Objective-C exceptions not caught by previous
               @catch clauses (if any).
    
               The @finally clause, if present, will be executed upon exit from
               the immediately preceding "@try ... @catch" section.  This will
               happen regardless of whether any exceptions are thrown, caught or
               rethrown inside the "@try ... @catch" section, analogously to the
                   cannot @throw an exception from Objective-C and "catch" it in
                   C++, or vice versa (i.e., "throw ... @catch").
    
               The -fobjc-exceptions switch also enables the use of
               synchronization blocks for thread-safe execution:
    
                         @synchronized (ObjCClass *guard) {
                           ...
                         }
    
               Upon entering the @synchronized block, a thread of execution shall
               first check whether a lock has been placed on the corresponding
               "guard" object by another thread.  If it has, the current thread
               shall wait until the other thread relinquishes its lock.  Once
               "guard" becomes available, the current thread will place its own
               lock on it, execute the code contained in the @synchronized block,
               and finally relinquish the lock (thereby making "guard" available
               to other threads).
    
               Unlike Java, Objective-C does not allow for entire methods to be
               marked @synchronized.  Note that throwing exceptions out of
               @synchronized blocks is allowed, and will cause the guarding object
               to be unlocked properly.
    
           -fobjc-gc
               Enable garbage collection (GC) in Objective-C and Objective-C++
               programs.
    
           -freplace-objc-classes
               Emit a special marker instructing lldd(1) not to statically link in
               the resulting object file, and allow ddyylldd(1) to load it in at run
               time instead.  This is used in conjunction with the Fix-and-
               Continue debugging mode, where the object file in question may be
               recompiled and dynamically reloaded in the course of program
               execution, without the need to restart the program itself.
               Currently, Fix-and-Continue functionality is only available in
               conjunction with the NeXT runtime on Mac OS X 10.3 and later.
    
           -fzero-link
               When compiling for the NeXT runtime, the compiler ordinarily
               replaces calls to "objc_getClass("...")" (when the name of the
               class is known at compile time) with static class references that
               get initialized at load time, which improves run-time performance.
               Specifying the -fzero-link flag suppresses this behavior and causes
               calls to "objc_getClass("...")"  to be retained.  This is useful in
               Zero-Link debugging mode, since it allows for individual class
               implementations to be modified during program execution.
    
           -gen-decls
               Dump interface declarations for all classes seen in the source file
               to a file named sourcename.decl.
    
           -Wselector (Objective-C and Objective-C++ only)
               Warn if multiple methods of different types for the same selector
               are found during compilation.  The check is performed on the list
               of methods in the final stage of compilation.  Additionally, a
               check is performed for each selector appearing in a
               "@selector(...)"  expression, and a corresponding method for that
               selector has been found during compilation.  Because these checks
               scan the method table only at the end of compilation, these
               warnings are not produced if the final stage of compilation is not
               reached, for example because an error is found during compilation,
               or because the -fsyntax-only option is being used.
    
           -Wstrict-selector-match (Objective-C and Objective-C++ only)
               Warn if multiple methods with differing argument and/or return
               types are found for a given selector when attempting to send a
               message using this selector to a receiver of type "id" or "Class".
               When this flag is off (which is the default behavior), the compiler
               will omit such warnings if any differences found are confined to
               types which share the same size and alignment.
    
           -Wundeclared-selector (Objective-C and Objective-C++ only)
               Warn if a "@selector(...)" expression referring to an undeclared
               selector is found.  A selector is considered undeclared if no
               method with that name has been declared before the "@selector(...)"
               expression, either explicitly in an @interface or @protocol
               declaration, or implicitly in an @implementation section.  This
               option always performs its checks as soon as a "@selector(...)"
               expression is found, while -Wselector only performs its checks in
               the final stage of compilation.  This also enforces the coding
               style convention that methods and selectors must be declared before
               being used.
    
           -print-objc-runtime-info
               Generate C header describing the largest structure that is passed
               by value, if any.
    
       Options to Control Diagnostic Messages Formatting
           Traditionally, diagnostic messages have been formatted irrespective of
           the output device's aspect (e.g. its width, ...).  The options
           described below can be used to control the diagnostic messages
           formatting algorithm, e.g. how many characters per line, how often
           source location information should be reported.  Right now, only the
           C++ front end can honor these options.  However it is expected, in the
           near future, that the remaining front ends would be able to digest them
           correctly.
    
           -fmessage-length=n
               Try to format error messages so that they fit on lines of about n
               characters.  The default is 72 characters for g++ and 0 for the
               rest of the front ends supported by GCC.  If n is zero, then no
               line-wrapping will be done; each error message will appear on a
               single line.
    
           -fdiagnostics-show-option
               This option instructs the diagnostic machinery to add text to each
               diagnostic emitted, which indicates which command line option
               directly controls that diagnostic, when such an option is known to
               the diagnostic machinery.
    
           -Wcoverage-mismatch
               Warn if feedback profiles do not match when using the -fprofile-use
               option.  If a source file was changed between -fprofile-gen and
               -fprofile-use, the files with the profile feedback can fail to
               match the source file and GCC can not use the profile feedback
               information.  By default, GCC emits an error message in this case.
               The option -Wcoverage-mismatch emits a warning instead of an error.
               GCC does not use appropriate feedback profiles, so using this
               option can result in poorly optimized code.  This option is useful
               only in the case of very minor changes such as bug fixes to an
               existing code-base.
    
       Options to Request or Suppress Warnings
           Warnings are diagnostic messages that report constructions which are
           not inherently erroneous but which are risky or suggest there may have
           been an error.
    
           The following language-independent options do not enable specific
           warnings but control the kinds of diagnostics produced by GCC.
    
           -fsyntax-only
               Check the code for syntax errors, but don't do anything beyond
               that.
    
           -w  Inhibit all warning messages.
    
           -Werror
               Make all warnings into errors.
    
           -Werror=
               Make the specified warning into an error.  The specifier for a
               warning is appended, for example -Werror=switch turns the warnings
               controlled by -Wswitch into errors.  This switch takes a negative
               form, to be used to negate -Werror for specific warnings, for
               example -Wno-error=switch makes -Wswitch warnings not be errors,
               even when -Werror is in effect.  You can use the
               -fdiagnostics-show-option option to have each controllable warning
               amended with the option which controls it, to determine what to use
               with this option.
    
               Note that specifying -Werror=foo automatically implies -Wfoo.
               However, -Wno-error=foo does not imply anything.
    
           -Wfatal-errors
               This option causes the compiler to abort compilation on the first
               that do not follow ISO C and ISO C++.  For ISO C, follows the
               version of the ISO C standard specified by any -std option used.
    
               Valid ISO C and ISO C++ programs should compile properly with or
               without this option (though a rare few will require -ansi or a -std
               option specifying the required version of ISO C).  However, without
               this option, certain GNU extensions and traditional C and C++
               features are supported as well.  With this option, they are
               rejected.
    
               -pedantic does not cause warning messages for use of the alternate
               keywords whose names begin and end with __.  Pedantic warnings are
               also disabled in the expression that follows "__extension__".
               However, only system header files should use these escape routes;
               application programs should avoid them.
    
               Some users try to use -pedantic to check programs for strict ISO C
               conformance.  They soon find that it does not do quite what they
               want: it finds some non-ISO practices, but not all---only those for
               which ISO C requires a diagnostic, and some others for which
               diagnostics have been added.
    
               A feature to report any failure to conform to ISO C might be useful
               in some instances, but would require considerable additional work
               and would be quite different from -pedantic.  We don't have plans
               to support such a feature in the near future.
    
               Where the standard specified with -std represents a GNU extended
               dialect of C, such as gnu89 or gnu99, there is a corresponding base
               standard, the version of ISO C on which the GNU extended dialect is
               based.  Warnings from -pedantic are given where they are required
               by the base standard.  (It would not make sense for such warnings
               to be given only for features not in the specified GNU C dialect,
               since by definition the GNU dialects of C include all features the
               compiler supports with the given option, and there would be nothing
               to warn about.)
    
           -pedantic-errors
               Like -pedantic, except that errors are produced rather than
               warnings.
    
           -Wall
               This enables all the warnings about constructions that some users
               consider questionable, and that are easy to avoid (or modify to
               prevent the warning), even in conjunction with macros.  This also
               enables some language-specific warnings described in C++ Dialect
               Options and Objective-C and Objective-C++ Dialect Options.
    
               -Wall turns on the following warning flags:
    
               -Waddress -Warray-bounds (only with -O2) -Wc++0x-compat
               -Wchar-subscripts -Wimplicit-int -Wimplicit-function-declaration
               of them must be enabled individually.
    
           -Wextra
               This enables some extra warning flags that are not enabled by
               -Wall. (This option used to be called -W.  The older name is still
               supported, but the newer name is more descriptive.)
    
               -Wclobbered -Wempty-body -Wignored-qualifiers
               -Wmissing-field-initializers -Wmissing-parameter-type (C only)
               -Wold-style-declaration (C only) -Woverride-init -Wsign-compare
               -Wtype-limits -Wuninitialized -Wunused-parameter (only with
               -Wunused or -Wall)
    
               The option -Wextra also prints warning messages for the following
               cases:
    
               ?   A pointer is compared against integer zero with <, <=, >, or
                   >=.
    
               ?   (C++ only) An enumerator and a non-enumerator both appear in a
                   conditional expression.
    
               ?   (C++ only) Ambiguous virtual bases.
    
               ?   (C++ only) Subscripting an array which has been declared
                   register.
    
               ?   (C++ only) Taking the address of a variable which has been
                   declared register.
    
               ?   (C++ only) A base class is not initialized in a derived class'
                   copy constructor.
    
           -Wchar-subscripts
               Warn if an array subscript has type "char".  This is a common cause
               of error, as programmers often forget that this type is signed on
               some machines.  This warning is enabled by -Wall.
    
           -Wcomment
               Warn whenever a comment-start sequence /* appears in a /* comment,
               or whenever a Backslash-Newline appears in a // comment.  This
               warning is enabled by -Wall.
    
           -Wformat
               Check calls to "printf" and "scanf", etc., to make sure that the
               arguments supplied have types appropriate to the format string
               specified, and that the conversions specified in the format string
               make sense.  This includes standard functions, and others specified
               by format attributes, in the "printf", "scanf", "strftime" and
               "strfmon" (an X/Open extension, not in the C standard) families (or
               other target-specific families).  Which functions are checked
               without format attributes having been specified depends on the
               Since -Wformat also checks for null format arguments for several
               functions, -Wformat also implies -Wnonnull.
    
               -Wformat is included in -Wall.  For more control over some aspects
               of format checking, the options -Wformat-y2k,
               -Wno-format-extra-args, -Wno-format-zero-length,
               -Wformat-nonliteral, -Wformat-security, and -Wformat=2 are
               available, but are not included in -Wall.
    
           -Wformat-y2k
               If -Wformat is specified, also warn about "strftime" formats which
               may yield only a two-digit year.
    
           -Wno-format-contains-nul
               If -Wformat is specified, do not warn about format strings that
               contain NUL bytes.
    
           -Wno-format-extra-args
               If -Wformat is specified, do not warn about excess arguments to a
               "printf" or "scanf" format function.  The C standard specifies that
               such arguments are ignored.
    
               Where the unused arguments lie between used arguments that are
               specified with $ operand number specifications, normally warnings
               are still given, since the implementation could not know what type
               to pass to "va_arg" to skip the unused arguments.  However, in the
               case of "scanf" formats, this option will suppress the warning if
               the unused arguments are all pointers, since the Single Unix
               Specification says that such unused arguments are allowed.
    
           -Wno-format-zero-length (C and Objective-C only)
               If -Wformat is specified, do not warn about zero-length formats.
               The C standard specifies that zero-length formats are allowed.
    
           -Wformat-nonliteral
               If -Wformat is specified, also warn if the format string is not a
               string literal and so cannot be checked, unless the format function
               takes its format arguments as a "va_list".
    
           -Wformat-security
               If -Wformat is specified, also warn about uses of format functions
               that represent possible security problems.  At present, this warns
               about calls to "printf" and "scanf" functions where the format
               string is not a string literal and there are no format arguments,
               as in "printf (foo);".  This may be a security hole if the format
               string came from untrusted input and contains %n.  (This is
               currently a subset of what -Wformat-nonliteral warns about, but in
               future warnings may be added to -Wformat-security that are not
               included in -Wformat-nonliteral.)
    
           -Wformat=2
               Enable -Wformat plus format checks not included in -Wformat.
    
               For example, GCC will warn about "i" being uninitialized in the
               following snippet only when -Winit-self has been specified:
    
                       int f()
                       {
                         int i = i;
                         return i;
                       }
    
           -Wimplicit-int (C and Objective-C only)
               Warn when a declaration does not specify a type.  This warning is
               enabled by -Wall.
    
           -Wimplicit-function-declaration (C and Objective-C only)
               Give a warning whenever a function is used before being declared.
               In C99 mode (-std=c99 or -std=gnu99), this warning is enabled by
               default and it is made into an error by -pedantic-errors. This
               warning is also enabled by -Wall.
    
           -Wimplicit
               Same as -Wimplicit-int and -Wimplicit-function-declaration.  This
               warning is enabled by -Wall.
    
           -Wignored-qualifiers (C and C++ only)
               Warn if the return type of a function has a type qualifier such as
               "const".  For ISO C such a type qualifier has no effect, since the
               value returned by a function is not an lvalue.  For C++, the
               warning is only emitted for scalar types or "void".  ISO C
               prohibits qualified "void" return types on function definitions, so
               such return types always receive a warning even without this
               option.
    
               This warning is also enabled by -Wextra.
    
           -Wmain
               Warn if the type of main is suspicious.  main should be a function
               with external linkage, returning int, taking either zero arguments,
               two, or three arguments of appropriate types.  This warning is
               enabled by default in C++ and is enabled by either -Wall or
               -pedantic.
    
           -Wmissing-braces
               Warn if an aggregate or union initializer is not fully bracketed.
               In the following example, the initializer for a is not fully
               bracketed, but that for b is fully bracketed.
    
                       int a[2][2] = { 0, 1, 2, 3 };
                       int b[2][2] = { { 0, 1 }, { 2, 3 } };
    
               This warning is enabled by -Wall.
    
               "if" statement an "else" branch belongs.  Here is an example of
               such a case:
    
                       {
                         if (a)
                           if (b)
                             foo ();
                         else
                           bar ();
                       }
    
               In C/C++, every "else" branch belongs to the innermost possible
               "if" statement, which in this example is "if (b)".  This is often
               not what the programmer expected, as illustrated in the above
               example by indentation the programmer chose.  When there is the
               potential for this confusion, GCC will issue a warning when this
               flag is specified.  To eliminate the warning, add explicit braces
               around the innermost "if" statement so there is no way the "else"
               could belong to the enclosing "if".  The resulting code would look
               like this:
    
                       {
                         if (a)
                           {
                             if (b)
                               foo ();
                             else
                               bar ();
                           }
                       }
    
               This warning is enabled by -Wall.
    
           -Wsequence-point
               Warn about code that may have undefined semantics because of
               violations of sequence point rules in the C and C++ standards.
    
               The C and C++ standards defines the order in which expressions in a
               C/C++ program are evaluated in terms of sequence points, which
               represent a partial ordering between the execution of parts of the
               program: those executed before the sequence point, and those
               executed after it.  These occur after the evaluation of a full
               expression (one which is not part of a larger expression), after
               the evaluation of the first operand of a "&&", "||", "? :" or ","
               (comma) operator, before a function is called (but after the
               evaluation of its arguments and the expression denoting the called
               function), and in certain other places.  Other than as expressed by
               the sequence point rules, the order of evaluation of subexpressions
               of an expression is not specified.  All these rules describe only a
               partial order rather than a total order, since, for example, if two
               functions are called within one expression with no sequence point
               between them, the order in which the functions are called is not
               b[n++]" and "a[i++] = i;".  Some more complicated cases are not
               diagnosed by this option, and it may give an occasional false
               positive result, but in general it has been found fairly effective
               at detecting this sort of problem in programs.
    
               The standard is worded confusingly, therefore there is some debate
               over the precise meaning of the sequence point rules in subtle
               cases.  Links to discussions of the problem, including proposed
               formal definitions, may be found on the GCC readings page, at
               <http://gcc.gnu.org/readings.html>.
    
               This warning is enabled by -Wall for C and C++.
    
           -Wreturn-type
               Warn whenever a function is defined with a return-type that
               defaults to "int".  Also warn about any "return" statement with no
               return-value in a function whose return-type is not "void" (falling
               off the end of the function body is considered returning without a
               value), and about a "return" statement with a expression in a
               function whose return-type is "void".
    
               For C++, a function without return type always produces a
               diagnostic message, even when -Wno-return-type is specified.  The
               only exceptions are main and functions defined in system headers.
    
               This warning is enabled by -Wall.
    
           -Wswitch
               Warn whenever a "switch" statement has an index of enumerated type
               and lacks a "case" for one or more of the named codes of that
               enumeration.  (The presence of a "default" label prevents this
               warning.)  "case" labels outside the enumeration range also provoke
               warnings when this option is used.  This warning is enabled by
               -Wall.
    
           -Wswitch-default
               Warn whenever a "switch" statement does not have a "default" case.
    
           -Wswitch-enum
               Warn whenever a "switch" statement has an index of enumerated type
               and lacks a "case" for one or more of the named codes of that
               enumeration.  "case" labels outside the enumeration range also
               provoke warnings when this option is used.
    
           -Wsync-nand (C and C++ only)
               Warn when "__sync_fetch_and_nand" and "__sync_nand_and_fetch"
               built-in functions are used.  These functions changed semantics in
               GCC 4.4.
    
           -Wtrigraphs
               Warn if any trigraphs are encountered that might change the meaning
               of the program (trigraphs within comments are not warned about).
    
           -Wunused-function
               Warn whenever a static function is declared but not defined or a
               non-inline static function is unused.  This warning is enabled by
               -Wall.
    
           -Wunused-label
               Warn whenever a label is declared but not used.  This warning is
               enabled by -Wall.
    
               To suppress this warning use the unused attribute.
    
           -Wunused-parameter
               Warn whenever a function parameter is unused aside from its
               declaration.
    
               To suppress this warning use the unused attribute.
    
           -Wunused-variable
               Warn whenever a local variable or non-constant static variable is
               unused aside from its declaration.  This warning is enabled by
               -Wall.
    
               To suppress this warning use the unused attribute.
    
           -Wunused-value
               Warn whenever a statement computes a result that is explicitly not
               used. To suppress this warning cast the unused expression to void.
               This includes an expression-statement or the left-hand side of a
               comma expression that contains no side effects. For example, an
               expression such as x[i,j] will cause a warning, while x[(void)i,j]
               will not.
    
               This warning is enabled by -Wall.
    
           -Wunused
               All the above -Wunused options combined.
    
               In order to get a warning about an unused function parameter, you
               must either specify -Wextra -Wunused (note that -Wall implies
               -Wunused), or separately specify -Wunused-parameter.
    
           -Wuninitialized
               Warn if an automatic variable is used without first being
               initialized or if a variable may be clobbered by a "setjmp" call.
               In C++, warn if a non-static reference or non-static const member
               appears in a class without constructors.
    
               If you want to warn about code which uses the uninitialized value
               of the variable in its own initializer, use the -Winit-self option.
    
               These warnings occur for individual uninitialized or clobbered
               elements of structure, union or array variables as well as for
    
                       {
                         int x;
                         switch (y)
                           {
                           case 1: x = 1;
                             break;
                           case 2: x = 4;
                             break;
                           case 3: x = 5;
                           }
                         foo (x);
                       }
    
               If the value of "y" is always 1, 2 or 3, then "x" is always
               initialized, but GCC doesn't know this.  Here is another common
               case:
    
                       {
                         int save_y;
                         if (change_y) save_y = y, y = new_y;
                         ...
                         if (change_y) y = save_y;
                       }
    
               This has no bug because "save_y" is used only if it is set.
    
               This option also warns when a non-volatile automatic variable might
               be changed by a call to "longjmp".  These warnings as well are
               possible only in optimizing compilation.
    
               The compiler sees only the calls to "setjmp".  It cannot know where
               "longjmp" will be called; in fact, a signal handler could call it
               at any point in the code.  As a result, you may get a warning even
               when there is in fact no problem because "longjmp" cannot in fact
               be called at the place which would cause a problem.
    
               Some spurious warnings can be avoided if you declare all the
               functions you use that never return as "noreturn".
    
               This warning is enabled by -Wall or -Wextra.
    
           -Wunknown-pragmas
               Warn when a #pragma directive is encountered which is not
               understood by GCC.  If this command line option is used, warnings
               will even be issued for unknown pragmas in system header files.
               This is not the case if the warnings were only enabled by the -Wall
               command line option.
    
           -Wno-pragmas
               Do not warn about misuses of pragmas, such as incorrect parameters,
               invalid syntax, or conflicts between pragmas.  See also
               correspond to more effort, similar to the way -O works.
               -Wstrict-aliasing is equivalent to -Wstrict-aliasing=n, with n=3.
    
               Level 1: Most aggressive, quick, least accurate.  Possibly useful
               when higher levels do not warn but -fstrict-aliasing still breaks
               the code, as it has very few false negatives.  However, it has many
               false positives.  Warns for all pointer conversions between
               possibly incompatible types, even if never dereferenced.  Runs in
               the frontend only.
    
               Level 2: Aggressive, quick, not too precise.  May still have many
               false positives (not as many as level 1 though), and few false
               negatives (but possibly more than level 1).  Unlike level 1, it
               only warns when an address is taken.  Warns about incomplete types.
               Runs in the frontend only.
    
               Level 3 (default for -Wstrict-aliasing): Should have very few false
               positives and few false negatives.  Slightly slower than levels 1
               or 2 when optimization is enabled.  Takes care of the common
               punn+dereference pattern in the frontend: "*(int*)&some_float".  If
               optimization is enabled, it also runs in the backend, where it
               deals with multiple statement cases using flow-sensitive points-to
               information.  Only warns when the converted pointer is
               dereferenced.  Does not warn about incomplete types.
    
           -Wstrict-overflow
           -Wstrict-overflow=n
               This option is only active when -fstrict-overflow is active.  It
               warns about cases where the compiler optimizes based on the
               assumption that signed overflow does not occur.  Note that it does
               not warn about all cases where the code might overflow: it only
               warns about cases where the compiler implements some optimization.
               Thus this warning depends on the optimization level.
    
               An optimization which assumes that signed overflow does not occur
               is perfectly safe if the values of the variables involved are such
               that overflow never does, in fact, occur.  Therefore this warning
               can easily give a false positive: a warning about code which is not
               actually a problem.  To help focus on important issues, several
               warning levels are defined.  No warnings are issued for the use of
               undefined signed overflow when estimating how many iterations a
               loop will require, in particular when determining whether a loop
               will be executed at all.
    
               -Wstrict-overflow=1
                   Warn about cases which are both questionable and easy to avoid.
                   For example: "x + 1 > x"; with -fstrict-overflow, the compiler
                   will simplify this to 1.  This level of -Wstrict-overflow is
                   enabled by -Wall; higher levels are not, and must be explicitly
                   requested.
    
               -Wstrict-overflow=2
                   2".
    
               -Wstrict-overflow=5
                   Also warn about cases where the compiler reduces the magnitude
                   of a constant involved in a comparison.  For example: "x + 2 >
                   y" will be simplified to "x + 1 >= y".  This is reported only
                   at the highest warning level because this simplification
                   applies to many comparisons, so this warning level will give a
                   very large number of false positives.
    
           -Warray-bounds
               This option is only active when -ftree-vrp is active (default for
               -O2 and above). It warns about subscripts to arrays that are always
               out of bounds. This warning is enabled by -Wall.
    
           -Wno-div-by-zero
               Do not warn about compile-time integer division by zero.  Floating
               point division by zero is not warned about, as it can be a
               legitimate way of obtaining infinities and NaNs.
    
           -Wsystem-headers
               Print warning messages for constructs found in system header files.
               Warnings from system headers are normally suppressed, on the
               assumption that they usually do not indicate real problems and
               would only make the compiler output harder to read.  Using this
               command line option tells GCC to emit warnings from system headers
               as if they occurred in user code.  However, note that using -Wall
               in conjunction with this option will not warn about unknown pragmas
               in system headers---for that, -Wunknown-pragmas must also be used.
    
           -Wfloat-equal
               Warn if floating point values are used in equality comparisons.
    
               The idea behind this is that sometimes it is convenient (for the
               programmer) to consider floating-point values as approximations to
               infinitely precise real numbers.  If you are doing this, then you
               need to compute (by analyzing the code, or in some other way) the
               maximum or likely maximum error that the computation introduces,
               and allow for it when performing comparisons (and when producing
               output, but that's a different problem).  In particular, instead of
               testing for equality, you would check to see whether the two values
               have ranges that overlap; and this is done with the relational
               operators, so equality comparisons are probably mistaken.
    
           -Wtraditional (C and Objective-C only)
               Warn about certain constructs that behave differently in
               traditional and ISO C.  Also warn about ISO C constructs that have
               no traditional C equivalent, and/or problematic constructs which
               should be avoided.
    
               ?   Macro parameters that appear within string literals in the
                   macro body.  In traditional C macro replacement takes place
    
               ?   The unary plus operator.
    
               ?   The U integer constant suffix, or the F or L floating point
                   constant suffixes.  (Traditional C does support the L suffix on
                   integer constants.)  Note, these suffixes appear in macros
                   defined in the system headers of most modern systems, e.g. the
                   _MIN/_MAX macros in "<limits.h>".  Use of these macros in user
                   code might normally lead to spurious warnings, however GCC's
                   integrated preprocessor has enough context to avoid warning in
                   these cases.
    
               ?   A function declared external in one block and then used after
                   the end of the block.
    
               ?   A "switch" statement has an operand of type "long".
    
               ?   A non-"static" function declaration follows a "static" one.
                   This construct is not accepted by some traditional C compilers.
    
               ?   The ISO type of an integer constant has a different width or
                   signedness from its traditional type.  This warning is only
                   issued if the base of the constant is ten.  I.e. hexadecimal or
                   octal values, which typically represent bit patterns, are not
                   warned about.
    
               ?   Usage of ISO string concatenation is detected.
    
               ?   Initialization of automatic aggregates.
    
               ?   Identifier conflicts with labels.  Traditional C lacks a
                   separate namespace for labels.
    
               ?   Initialization of unions.  If the initializer is zero, the
                   warning is omitted.  This is done under the assumption that the
                   zero initializer in user code appears conditioned on e.g.
                   "__STDC__" to avoid missing initializer warnings and relies on
                   default initialization to zero in the traditional C case.
    
               ?   Conversions by prototypes between fixed/floating point values
                   and vice versa.  The absence of these prototypes when compiling
                   with traditional C would cause serious problems.  This is a
                   subset of the possible conversion warnings, for the full set
                   use -Wtraditional-conversion.
    
               ?   Use of ISO C style function definitions.  This warning
                   intentionally is not issued for prototype declarations or
                   variadic functions because these ISO C features will appear in
                   your code when using libiberty's traditional C compatibility
                   macros, "PARAMS" and "VPARAMS".  This warning is also bypassed
                   for nested functions because that feature is already a GCC
                   extension and thus not relevant to traditional C compatibility.
    
           -Wundef
               Warn if an undefined identifier is evaluated in an #if directive.
    
           -Wno-endif-labels
               Do not warn whenever an #else or an #endif are followed by text.
    
           -Wshadow
               Warn whenever a local variable shadows another local variable,
               parameter or global variable or whenever a built-in function is
               shadowed.
    
           -Wlarger-than=len
               Warn whenever an object of larger than len bytes is defined.
    
           -Wframe-larger-than=len
               Warn if the size of a function frame is larger than len bytes.  The
               computation done to determine the stack frame size is approximate
               and not conservative.  The actual requirements may be somewhat
               greater than len even if you do not get a warning.  In addition,
               any space allocated via "alloca", variable-length arrays, or
               related constructs is not included by the compiler when determining
               whether or not to issue a warning.
    
           -Wunsafe-loop-optimizations
               Warn if the loop cannot be optimized because the compiler could not
               assume anything on the bounds of the loop indices.  With
               -funsafe-loop-optimizations warn if the compiler made such
               assumptions.
    
           -Wno-pedantic-ms-format (MinGW targets only)
               Disables the warnings about non-ISO "printf" / "scanf" format width
               specifiers "I32", "I64", and "I" used on Windows targets depending
               on the MS runtime, when you are using the options -Wformat and
               -pedantic without gnu-extensions.
    
           -Wpointer-arith
               Warn about anything that depends on the "size of" a function type
               or of "void".  GNU C assigns these types a size of 1, for
               convenience in calculations with "void *" pointers and pointers to
               functions.  In C++, warn also when an arithmetic operation involves
               "NULL".  This warning is also enabled by -pedantic.
    
           -Wtype-limits
               Warn if a comparison is always true or always false due to the
               limited range of the data type, but do not warn for constant
               expressions.  For example, warn if an unsigned variable is compared
               against zero with < or >=.  This warning is also enabled by
               -Wextra.
    
           -Wbad-function-cast (C and Objective-C only)
               Warn whenever a function call is cast to a non-matching type.  For
               example, warn if "int malloc()" is cast to "anything *".
               cast to an ordinary "char *".
    
           -Wcast-align
               Warn whenever a pointer is cast such that the required alignment of
               the target is increased.  For example, warn if a "char *" is cast
               to an "int *" on machines where integers can only be accessed at
               two- or four-byte boundaries.
    
           -Wwrite-strings
               When compiling C, give string constants the type "const
               char[length]" so that copying the address of one into a non-"const"
               "char *" pointer will get a warning.  These warnings will help you
               find at compile time code that can try to write into a string
               constant, but only if you have been very careful about using
               "const" in declarations and prototypes.  Otherwise, it will just be
               a nuisance. This is why we did not make -Wall request these
               warnings.
    
               When compiling C++, warn about the deprecated conversion from
               string literals to "char *".  This warning is enabled by default
               for C++ programs.
    
           -Wclobbered
               Warn for variables that might be changed by longjmp or vfork.  This
               warning is also enabled by -Wextra.
    
           -Wconversion
               Warn for implicit conversions that may alter a value. This includes
               conversions between real and integer, like "abs (x)" when "x" is
               "double"; conversions between signed and unsigned, like "unsigned
               ui = -1"; and conversions to smaller types, like "sqrtf (M_PI)". Do
               not warn for explicit casts like "abs ((int) x)" and "ui =
               (unsigned) -1", or if the value is not changed by the conversion
               like in "abs (2.0)".  Warnings about conversions between signed and
               unsigned integers can be disabled by using -Wno-sign-conversion.
    
               For C++, also warn for conversions between "NULL" and non-pointer
               types; confusing overload resolution for user-defined conversions;
               and conversions that will never use a type conversion operator:
               conversions to "void", the same type, a base class or a reference
               to them. Warnings about conversions between signed and unsigned
               integers are disabled by default in C++ unless -Wsign-conversion is
               explicitly enabled.
    
           -Wempty-body
               Warn if an empty body occurs in an if, else or do while statement.
               This warning is also enabled by -Wextra.
    
           -Wenum-compare (C++ and Objective-C++ only)
               Warn about a comparison between values of different enum types.
               This warning is enabled by default.
    
               Warn about suspicious uses of memory addresses. These include using
               the address of a function in a conditional expression, such as
               "void func(void); if (func)", and comparisons against the memory
               address of a string literal, such as "if (x == "abc")".  Such uses
               typically indicate a programmer error: the address of a function
               always evaluates to true, so their use in a conditional usually
               indicate that the programmer forgot the parentheses in a function
               call; and comparisons against string literals result in unspecified
               behavior and are not portable in C, so they usually indicate that
               the programmer intended to use "strcmp".  This warning is enabled
               by -Wall.
    
           -Wlogical-op
               Warn about suspicious uses of logical operators in expressions.
               This includes using logical operators in contexts where a bit-wise
               operator is likely to be expected.
    
           -Waggregate-return
               Warn if any functions that return structures or unions are defined
               or called.  (In languages where you can return an array, this also
               elicits a warning.)
    
           -Wno-attributes
               Do not warn if an unexpected "__attribute__" is used, such as
               unrecognized attributes, function attributes applied to variables,
               etc.  This will not stop errors for incorrect use of supported
               attributes.
    
           -Wno-builtin-macro-redefined
               Do not warn if certain built-in macros are redefined.  This
               suppresses warnings for redefinition of "__TIMESTAMP__",
               "__TIME__", "__DATE__", "__FILE__", and "__BASE_FILE__".
    
           -Wstrict-prototypes (C and Objective-C only)
               Warn if a function is declared or defined without specifying the
               argument types.  (An old-style function definition is permitted
               without a warning if preceded by a declaration which specifies the
               argument types.)
    
           -Wold-style-declaration (C and Objective-C only)
               Warn for obsolescent usages, according to the C Standard, in a
               declaration. For example, warn if storage-class specifiers like
               "static" are not the first things in a declaration.  This warning
               is also enabled by -Wextra.
    
           -Wold-style-definition (C and Objective-C only)
               Warn if an old-style function definition is used.  A warning is
               given even if there is a previous prototype.
    
           -Wmissing-parameter-type (C and Objective-C only)
               A function parameter is declared without a type specifier in
               K&R-style functions:
               prototype.  Use this option to detect global functions that are not
               declared in header files.  In C++, no warnings are issued for
               function templates, or for inline functions, or for functions in
               anonymous namespaces.
    
           -Wmissing-field-initializers
               Warn if a structure's initializer has some fields missing.  For
               example, the following code would cause such a warning, because
               "x.h" is implicitly zero:
    
                       struct s { int f, g, h; };
                       struct s x = { 3, 4 };
    
               This option does not warn about designated initializers, so the
               following modification would not trigger a warning:
    
                       struct s { int f, g, h; };
                       struct s x = { .f = 3, .g = 4 };
    
               This warning is included in -Wextra.  To get other -Wextra warnings
               without this one, use -Wextra -Wno-missing-field-initializers.
    
           -Wmissing-noreturn
               Warn about functions which might be candidates for attribute
               "noreturn".  Note these are only possible candidates, not absolute
               ones.  Care should be taken to manually verify functions actually
               do not ever return before adding the "noreturn" attribute,
               otherwise subtle code generation bugs could be introduced.  You
               will not get a warning for "main" in hosted C environments.
    
           -Wmissing-format-attribute
               Warn about function pointers which might be candidates for "format"
               attributes.  Note these are only possible candidates, not absolute
               ones.  GCC will guess that function pointers with "format"
               attributes that are used in assignment, initialization, parameter
               passing or return statements should have a corresponding "format"
               attribute in the resulting type.  I.e. the left-hand side of the
               assignment or initialization, the type of the parameter variable,
               or the return type of the containing function respectively should
               also have a "format" attribute to avoid the warning.
    
               GCC will also warn about function definitions which might be
               candidates for "format" attributes.  Again, these are only possible
               candidates.  GCC will guess that "format" attributes might be
               appropriate for any function that calls a function like "vprintf"
               or "vscanf", but this might not always be the case, and some
               functions for which "format" attributes are appropriate may not be
               detected.
    
           -Wno-multichar
               Do not warn if a multicharacter constant ('FOOF') is used.  Usually
               they indicate a typo in the user's code, as they have
               There are four levels of warning that GCC supports.  The default is
               -Wnormalized=nfc, which warns about any identifier which is not in
               the ISO 10646 "C" normalized form, NFC.  NFC is the recommended
               form for most uses.
    
               Unfortunately, there are some characters which ISO C and ISO C++
               allow in identifiers that when turned into NFC aren't allowable as
               identifiers.  That is, there's no way to use these symbols in
               portable ISO C or C++ and have all your identifiers in NFC.
               -Wnormalized=id suppresses the warning for these characters.  It is
               hoped that future versions of the standards involved will correct
               this, which is why this option is not the default.
    
               You can switch the warning off for all characters by writing
               -Wnormalized=none.  You would only want to do this if you were
               using some other normalization scheme (like "D"), because otherwise
               you can easily create bugs that are literally impossible to see.
    
               Some characters in ISO 10646 have distinct meanings but look
               identical in some fonts or display methodologies, especially once
               formatting has been applied.  For instance "\u207F", "SUPERSCRIPT
               LATIN SMALL LETTER N", will display just like a regular "n" which
               has been placed in a superscript.  ISO 10646 defines the NFKC
               normalization scheme to convert all these into a standard form as
               well, and GCC will warn if your code is not in NFKC if you use
               -Wnormalized=nfkc.  This warning is comparable to warning about
               every identifier that contains the letter O because it might be
               confused with the digit 0, and so is not the default, but may be
               useful as a local coding convention if the programming environment
               is unable to be fixed to display these characters distinctly.
    
           -Wno-deprecated
               Do not warn about usage of deprecated features.
    
           -Wno-deprecated-declarations
               Do not warn about uses of functions, variables, and types marked as
               deprecated by using the "deprecated" attribute.
    
           -Wno-overflow
               Do not warn about compile-time overflow in constant expressions.
    
           -Woverride-init (C and Objective-C only)
               Warn if an initialized field without side effects is overridden
               when using designated initializers.
    
               This warning is included in -Wextra.  To get other -Wextra warnings
               without this one, use -Wextra -Wno-override-init.
    
           -Wpacked
               Warn if a structure is given the packed attribute, but the packed
               attribute has no effect on the layout or size of the structure.
               Such structures may be mis-aligned for little benefit.  For
               The 4.1, 4.2 and 4.3 series of GCC ignore the "packed" attribute on
               bit-fields of type "char".  This has been fixed in GCC 4.4 but the
               change can lead to differences in the structure layout.  GCC
               informs you when the offset of such a field has changed in GCC 4.4.
               For example there is no longer a 4-bit padding between field "a"
               and "b" in this structure:
    
                       struct foo
                       {
                         char a:4;
                         char b:8;
                       } __attribute__ ((packed));
    
               This warning is enabled by default.  Use
               -Wno-packed-bitfield-compat to disable this warning.
    
           -Wpadded
               Warn if padding is included in a structure, either to align an
               element of the structure or to align the whole structure.
               Sometimes when this happens it is possible to rearrange the fields
               of the structure to reduce the padding and so make the structure
               smaller.
    
           -Wredundant-decls
               Warn if anything is declared more than once in the same scope, even
               in cases where multiple declaration is valid and changes nothing.
    
           -Wnested-externs (C and Objective-C only)
               Warn if an "extern" declaration is encountered within a function.
    
           -Wunreachable-code
               Warn if the compiler detects that code will never be executed.
    
               This option is intended to warn when the compiler detects that at
               least a whole line of source code will never be executed, because
               some condition is never satisfied or because it is after a
               procedure that never returns.
    
               It is possible for this option to produce a warning even though
               there are circumstances under which part of the affected line can
               be executed, so care should be taken when removing apparently-
               unreachable code.
    
               For instance, when a function is inlined, a warning may mean that
               the line is unreachable in only one inlined copy of the function.
    
               This option is not made part of -Wall because in a debugging
               version of a program there is often substantial code which checks
               correct functioning of the program and is, hopefully, unreachable
               because the program does work.  Another common use of unreachable
               code is to provide behavior which is selectable at compile-time.
    
               type.  According to the 1998 ISO C++ standard, applying offsetof to
               a non-POD type is undefined.  In existing C++ implementations,
               however, offsetof typically gives meaningful results even when
               applied to certain kinds of non-POD types. (Such as a simple struct
               that fails to be a POD type only by virtue of having a
               constructor.)  This flag is for users who are aware that they are
               writing nonportable code and who have deliberately chosen to ignore
               the warning about it.
    
               The restrictions on offsetof may be relaxed in a future version of
               the C++ standard.
    
           -Wno-int-to-pointer-cast (C and Objective-C only)
               Suppress warnings from casts to pointer type of an integer of a
               different size.
    
           -Wno-pointer-to-int-cast (C and Objective-C only)
               Suppress warnings from casts from a pointer to an integer type of a
               different size.
    
           -Winvalid-pch
               Warn if a precompiled header is found in the search path but can't
               be used.
    
           -Wlong-long
               Warn if long long type is used.  This is default.  To inhibit the
               warning messages, use -Wno-long-long.  Flags -Wlong-long and
               -Wno-long-long are taken into account only when -pedantic flag is
               used.
    
           -Wvariadic-macros
               Warn if variadic macros are used in pedantic ISO C90 mode, or the
               GNU alternate syntax when in pedantic ISO C99 mode.  This is
               default.  To inhibit the warning messages, use
               -Wno-variadic-macros.
    
           -Wvla
               Warn if variable length array is used in the code.  -Wno-vla will
               prevent the -pedantic warning of the variable length array.
    
           -Wvolatile-register-var
               Warn if a register variable is declared volatile.  The volatile
               modifier does not inhibit all optimizations that may eliminate
               reads and/or writes to register variables.  This warning is enabled
               by -Wall.
    
           -Wdisabled-optimization
               Warn if a requested optimization pass is disabled.  This warning
               does not generally indicate that there is anything wrong with your
               code; it merely indicates that GCC's optimizers were unable to
               handle the code effectively.  Often, the problem is that your code
               is too big or too complex; GCC will refuse to optimize programs
    
           -Wno-mudflap
               Suppress warnings about constructs that cannot be instrumented by
               -fmudflap.
    
           -Woverlength-strings
               Warn about string constants which are longer than the "minimum
               maximum" length specified in the C standard.  Modern compilers
               generally allow string constants which are much longer than the
               standard's minimum limit, but very portable programs should avoid
               using longer strings.
    
               The limit applies after string constant concatenation, and does not
               count the trailing NUL.  In C89, the limit was 509 characters; in
               C99, it was raised to 4095.  C++98 does not specify a normative
               minimum maximum, so we do not diagnose overlength strings in C++.
    
               This option is implied by -pedantic, and can be disabled with
               -Wno-overlength-strings.
    
       Options for Debugging Your Program or GCC
           GCC has various special options that are used for debugging either your
           program or GCC:
    
           -g  Produce debugging information in the operating system's native
               format (stabs, COFF, XCOFF, or DWARF 2).  GDB can work with this
               debugging information.
    
               On most systems that use stabs format, -g enables use of extra
               debugging information that only GDB can use; this extra information
               makes debugging work better in GDB but will probably make other
               debuggers crash or refuse to read the program.  If you want to
               control for certain whether to generate the extra information, use
               -gstabs+, -gstabs, -gxcoff+, -gxcoff, or -gvms (see below).
    
               GCC allows you to use -g with -O.  The shortcuts taken by optimized
               code may occasionally produce surprising results: some variables
               you declared may not exist at all; flow of control may briefly move
               where you did not expect it; some statements may not be executed
               because they compute constant results or their values were already
               at hand; some statements may execute in different places because
               they were moved out of loops.
    
               Nevertheless it proves possible to debug optimized output.  This
               makes it reasonable to use the optimizer for programs that might
               have bugs.
    
               The following options are useful when GCC is generated with the
               capability for more than one debugging format.
    
           -ggdb
               Produce debugging information for use by GDB.  This means to use
               the most expressive format available (DWARF 2, stabs, or the native
    
           -femit-class-debug-always
               Instead of emitting debugging information for a C++ class in only
               one object file, emit it in all object files using the class.  This
               option should be used only with debuggers that are unable to handle
               the way GCC normally emits debugging information for classes
               because using this option will increase the size of debugging
               information by as much as a factor of two.
    
           -gstabs+
               Produce debugging information in stabs format (if that is
               supported), using GNU extensions understood only by the GNU
               debugger (GDB).  The use of these extensions is likely to make
               other debuggers crash or refuse to read the program.
    
           -gcoff
               Produce debugging information in COFF format (if that is
               supported).  This is the format used by SDB on most System V
               systems prior to System V Release 4.
    
           -gxcoff
               Produce debugging information in XCOFF format (if that is
               supported).  This is the format used by the DBX debugger on IBM
               RS/6000 systems.
    
           -gxcoff+
               Produce debugging information in XCOFF format (if that is
               supported), using GNU extensions understood only by the GNU
               debugger (GDB).  The use of these extensions is likely to make
               other debuggers crash or refuse to read the program, and may cause
               assemblers other than the GNU assembler (GAS) to fail with an
               error.
    
           -gdwarf-version
               Produce debugging information in DWARF format (if that is
               supported).  This is the format used by DBX on IRIX 6.  The value
               of version may be either 2 or 3; the default version is 3.
    
               Note that with DWARF version 2 some ports require, and will always
               use, some non-conflicting DWARF 3 extensions in the unwind tables.
    
           -gstrict-dwarf
               Disallow using extensions of later DWARF standard version than
               selected with -gdwarf-version.  On most targets using non-
               conflicting DWARF extensions from later standard versions is
               allowed.
    
           -gno-strict-dwarf
               Allow using extensions of later DWARF standard version than
               selected with -gdwarf-version.
    
           -gvms
    
               Level 1 produces minimal information, enough for making backtraces
               in parts of the program that you don't plan to debug.  This
               includes descriptions of functions and external variables, but no
               information about local variables and no line numbers.
    
               Level 3 includes extra information, such as all the macro
               definitions present in the program.  Some debuggers support macro
               expansion when you use -g3.
    
               -gdwarf-2 does not accept a concatenated debug level, because GCC
               used to support an option -gdwarf that meant to generate debug
               information in version 1 of the DWARF format (which is very
               different from version 2), and it would have been too confusing.
               That debug format is long obsolete, but the option cannot be
               changed now.  Instead use an additional -glevel option to change
               the debug level for DWARF.
    
           -gtoggle
               Turn off generation of debug info, if leaving out this option would
               have generated it, or turn it on at level 2 otherwise.  The
               position of this argument in the command line does not matter, it
               takes effect after all other options are processed, and it does so
               only once, no matter how many times it is given.  This is mainly
               intended to be used with -fcompare-debug.
    
           -fdump-final-insns[=file]
               Dump the final internal representation (RTL) to file.  If the
               optional argument is omitted (or if file is "."), the name of the
               dump file will be determined by appending ".gkd" to the compilation
               output file name.
    
           -fcompare-debug[=opts]
               If no error occurs during compilation, run the compiler a second
               time, adding opts and -fcompare-debug-second to the arguments
               passed to the second compilation.  Dump the final internal
               representation in both compilations, and print an error if they
               differ.
    
               If the equal sign is omitted, the default -gtoggle is used.
    
               The environment variable GCC_COMPARE_DEBUG, if defined, non-empty
               and nonzero, implicitly enables -fcompare-debug.  If
               GCC_COMPARE_DEBUG is defined to a string starting with a dash, then
               it is used for opts, otherwise the default -gtoggle is used.
    
               -fcompare-debug=, with the equal sign but without opts, is
               equivalent to -fno-compare-debug, which disables the dumping of the
               final representation and the second compilation, preventing even
               GCC_COMPARE_DEBUG from taking effect.
    
               To verify full coverage during -fcompare-debug testing, set
    
               When this option is passed to the compiler driver, it causes the
               first compilation to be skipped, which makes it useful for little
               other than debugging the compiler proper.
    
           -feliminate-dwarf2-dups
               Compress DWARF2 debugging information by eliminating duplicated
               information about each symbol.  This option only makes sense when
               generating DWARF2 debugging information with -gdwarf-2.
    
           -femit-struct-debug-baseonly
               Emit debug information for struct-like types only when the base
               name of the compilation source file matches the base name of file
               in which the struct was defined.
    
               This option substantially reduces the size of debugging
               information, but at significant potential loss in type information
               to the debugger.  See -femit-struct-debug-reduced for a less
               aggressive option.  See -femit-struct-debug-detailed for more
               detailed control.
    
               This option works only with DWARF 2.
    
           -femit-struct-debug-reduced
               Emit debug information for struct-like types only when the base
               name of the compilation source file matches the base name of file
               in which the type was defined, unless the struct is a template or
               defined in a system header.
    
               This option significantly reduces the size of debugging
               information, with some potential loss in type information to the
               debugger.  See -femit-struct-debug-baseonly for a more aggressive
               option.  See -femit-struct-debug-detailed for more detailed
               control.
    
               This option works only with DWARF 2.
    
           -femit-struct-debug-detailed[=spec-list]
               Specify the struct-like types for which the compiler will generate
               debug information.  The intent is to reduce duplicate struct debug
               information between different object files within the same program.
    
               This option is a detailed version of -femit-struct-debug-reduced
               and -femit-struct-debug-baseonly, which will serve for most needs.
    
               A specification has the syntax
               [dir:|ind:][ord:|gen:](any|sys|base|none)
    
               The optional first word limits the specification to structs that
               are used directly (dir:) or used indirectly (ind:).  A struct type
               is used directly when it is the type of a variable, member.
               Indirect uses arise through pointers to structs.  That is, when use
               match the base of the name of the main compilation file.  In
               practice, this means that types declared in foo.c and foo.h will
               have debug information, but types declared in other header will
               not.  The value sys means those types satisfying base or declared
               in system or compiler headers.
    
               You may need to experiment to determine the best settings for your
               application.
    
               The default is -femit-struct-debug-detailed=all.
    
               This option works only with DWARF 2.
    
           -fno-merge-debug-strings
               Direct the linker to not merge together strings in the debugging
               information which are identical in different object files.  Merging
               is not supported by all assemblers or linkers.  Merging decreases
               the size of the debug information in the output file at the cost of
               increasing link processing time.  Merging is enabled by default.
    
           -fdebug-prefix-map=old=new
               When compiling files in directory old, record debugging information
               describing them as in new instead.
    
           -fno-dwarf2-cfi-asm
               Emit DWARF 2 unwind info as compiler generated ".eh_frame" section
               instead of using GAS ".cfi_*" directives.
    
           -p  Generate extra code to write profile information suitable for the
               analysis program prof.  You must use this option when compiling the
               source files you want data about, and you must also use it when
               linking.
    
           -pg Generate extra code to write profile information suitable for the
               analysis program gprof.  You must use this option when compiling
               the source files you want data about, and you must also use it when
               linking.
    
           -Q  Makes the compiler print out each function name as it is compiled,
               and print some statistics about each pass when it finishes.
    
           -ftime-report
               Makes the compiler print some statistics about the time consumed by
               each pass when it finishes.
    
           -fmem-report
               Makes the compiler print some statistics about permanent memory
               allocation when it finishes.
    
           -fpre-ipa-mem-report
           -fpost-ipa-mem-report
               Makes the compiler print some statistics about permanent memory
               for output file specified as -o dir/foo.o).
    
           --coverage
               This option is used to compile and link code instrumented for
               coverage analysis.  The option is a synonym for -fprofile-arcs
               -ftest-coverage (when compiling) and -lgcov (when linking).  See
               the documentation for those options for more details.
    
               ?   Compile the source files with -fprofile-arcs plus optimization
                   and code generation options.  For test coverage analysis, use
                   the additional -ftest-coverage option.  You do not need to
                   profile every source file in a program.
    
               ?   Link your object files with -lgcov or -fprofile-arcs (the
                   latter implies the former).
    
               ?   Run the program on a representative workload to generate the
                   arc profile information.  This may be repeated any number of
                   times.  You can run concurrent instances of your program, and
                   provided that the file system supports locking, the data files
                   will be correctly updated.  Also "fork" calls are detected and
                   correctly handled (double counting will not happen).
    
               ?   For profile-directed optimizations, compile the source files
                   again with the same optimization and code generation options
                   plus -fbranch-probabilities.
    
               ?   For test coverage analysis, use gcov to produce human readable
                   information from the .gcno and .gcda files.  Refer to the gcov
                   documentation for further information.
    
               With -fprofile-arcs, for each function of your program GCC creates
               a program flow graph, then finds a spanning tree for the graph.
               Only arcs that are not on the spanning tree have to be
               instrumented: the compiler adds code to count the number of times
               that these arcs are executed.  When an arc is the only exit or only
               entrance to a block, the instrumentation code can be added to the
               block; otherwise, a new basic block must be created to hold the
               instrumentation code.
    
           -ftest-coverage
               Produce a notes file that the gcov code-coverage utility can use to
               show program coverage.  Each source file's note file is called
               auxname.gcno.  Refer to the -fprofile-arcs option above for a
               description of auxname and instructions on how to generate test
               coverage data.  Coverage data will match the source files more
               closely, if you do not optimize.
    
           -fdbg-cnt-list
               Print the name and the counter upperbound for all debug counters.
    
           -fdbg-cnt=counter-value-list
               appending a pass number and a word to the dumpname.  dumpname is
               generated from the name of the output file, if explicitly specified
               and it is not an executable, otherwise it is the basename of the
               source file. These switches may have different effects when -E is
               used for preprocessing.
    
               Debug dumps can be enabled with a -fdump-rtl switch or some -d
               option letters.  Here are the possible letters for use in pass and
               letters, and their meanings:
    
               -fdump-rtl-alignments
                   Dump after branch alignments have been computed.
    
               -fdump-rtl-asmcons
                   Dump after fixing rtl statements that have unsatisfied in/out
                   constraints.
    
               -fdump-rtl-auto_inc_dec
                   Dump after auto-inc-dec discovery.  This pass is only run on
                   architectures that have auto inc or auto dec instructions.
    
               -fdump-rtl-barriers
                   Dump after cleaning up the barrier instructions.
    
               -fdump-rtl-bbpart
                   Dump after partitioning hot and cold basic blocks.
    
               -fdump-rtl-bbro
                   Dump after block reordering.
    
               -fdump-rtl-btl1
               -fdump-rtl-btl2
                   -fdump-rtl-btl1 and -fdump-rtl-btl2 enable dumping after the
                   two branch target load optimization passes.
    
               -fdump-rtl-bypass
                   Dump after jump bypassing and control flow optimizations.
    
               -fdump-rtl-combine
                   Dump after the RTL instruction combination pass.
    
               -fdump-rtl-compgotos
                   Dump after duplicating the computed gotos.
    
               -fdump-rtl-ce1
               -fdump-rtl-ce2
               -fdump-rtl-ce3
                   -fdump-rtl-ce1, -fdump-rtl-ce2, and -fdump-rtl-ce3 enable
                   dumping after the three if conversion passes.
    
               -fdump-rtl-cprop_hardreg
                   Dump after hard register copy propagation.
    
               -fdump-rtl-dce1
               -fdump-rtl-dce2
                   -fdump-rtl-dce1 and -fdump-rtl-dce2 enable dumping after the
                   two dead store elimination passes.
    
               -fdump-rtl-eh
                   Dump after finalization of EH handling code.
    
               -fdump-rtl-eh_ranges
                   Dump after conversion of EH handling range regions.
    
               -fdump-rtl-expand
                   Dump after RTL generation.
    
               -fdump-rtl-fwprop1
               -fdump-rtl-fwprop2
                   -fdump-rtl-fwprop1 and -fdump-rtl-fwprop2 enable dumping after
                   the two forward propagation passes.
    
               -fdump-rtl-gcse1
               -fdump-rtl-gcse2
                   -fdump-rtl-gcse1 and -fdump-rtl-gcse2 enable dumping after
                   global common subexpression elimination.
    
               -fdump-rtl-init-regs
                   Dump after the initialization of the registers.
    
               -fdump-rtl-initvals
                   Dump after the computation of the initial value sets.
    
               -fdump-rtl-into_cfglayout
                   Dump after converting to cfglayout mode.
    
               -fdump-rtl-ira
                   Dump after iterated register allocation.
    
               -fdump-rtl-jump
                   Dump after the second jump optimization.
    
               -fdump-rtl-loop2
                   -fdump-rtl-loop2 enables dumping after the rtl loop
                   optimization passes.
    
               -fdump-rtl-mach
                   Dump after performing the machine dependent reorganization
                   pass, if that pass exists.
    
               -fdump-rtl-mode_sw
                   Dump after removing redundant mode switches.
    
               -fdump-rtl-rnreg
               -fdump-rtl-regmove
                   Dump after the register move pass.
    
               -fdump-rtl-sched1
               -fdump-rtl-sched2
                   -fdump-rtl-sched1 and -fdump-rtl-sched2 enable dumping after
                   the basic block scheduling passes.
    
               -fdump-rtl-see
                   Dump after sign extension elimination.
    
               -fdump-rtl-seqabstr
                   Dump after common sequence discovery.
    
               -fdump-rtl-shorten
                   Dump after shortening branches.
    
               -fdump-rtl-sibling
                   Dump after sibling call optimizations.
    
               -fdump-rtl-split1
               -fdump-rtl-split2
               -fdump-rtl-split3
               -fdump-rtl-split4
               -fdump-rtl-split5
                   -fdump-rtl-split1, -fdump-rtl-split2, -fdump-rtl-split3,
                   -fdump-rtl-split4 and -fdump-rtl-split5 enable dumping after
                   five rounds of instruction splitting.
    
               -fdump-rtl-sms
                   Dump after modulo scheduling.  This pass is only run on some
                   architectures.
    
               -fdump-rtl-stack
                   Dump after conversion from GCC's "flat register file" registers
                   to the x87's stack-like registers.  This pass is only run on
                   x86 variants.
    
               -fdump-rtl-subreg1
               -fdump-rtl-subreg2
                   -fdump-rtl-subreg1 and -fdump-rtl-subreg2 enable dumping after
                   the two subreg expansion passes.
    
               -fdump-rtl-unshare
                   Dump after all rtl has been unshared.
    
               -fdump-rtl-vartrack
                   Dump after variable tracking.
    
               -fdump-rtl-vregs
                   Dump after converting virtual registers to hard registers.
    
                   information.
    
               -dD Dump all macro definitions, at the end of preprocessing, in
                   addition to normal output.
    
               -dH Produce a core dump whenever an error occurs.
    
               -dm Print statistics on memory usage, at the end of the run, to
                   standard error.
    
               -dp Annotate the assembler output with a comment indicating which
                   pattern and alternative was used.  The length of each
                   instruction is also printed.
    
               -dP Dump the RTL in the assembler output as a comment before each
                   instruction.  Also turns on -dp annotation.
    
               -dv For each of the other indicated dump files (-fdump-rtl-pass),
                   dump a representation of the control flow graph suitable for
                   viewing with VCG to file.pass.vcg.
    
               -dx Just generate RTL for a function instead of compiling it.
                   Usually used with -fdump-rtl-expand.
    
               -dy Dump debugging information during parsing, to standard error.
    
           -fdump-noaddr
               When doing debugging dumps, suppress address output.  This makes it
               more feasible to use diff on debugging dumps for compiler
               invocations with different compiler binaries and/or different text
               / bss / data / heap / stack / dso start locations.
    
           -fdump-unnumbered
               When doing debugging dumps, suppress instruction numbers and
               address output.  This makes it more feasible to use diff on
               debugging dumps for compiler invocations with different options, in
               particular with and without -g.
    
           -fdump-unnumbered-links
               When doing debugging dumps (see -d option above), suppress
               instruction numbers for the links to the previous and next
               instructions in a sequence.
    
           -fdump-translation-unit (C++ only)
           -fdump-translation-unit-options (C++ only)
               Dump a representation of the tree structure for the entire
               translation unit to a file.  The file name is made by appending .tu
               to the source file name.  If the -options form is used, options
               controls the details of the dump as described for the -fdump-tree
               options.
    
           -fdump-class-hierarchy (C++ only)
    
               cgraph
                   Dumps information about call-graph optimization, unused
                   function removal, and inlining decisions.
    
               inline
                   Dump after function inlining.
    
           -fdump-statistics-option
               Enable and control dumping of pass statistics in a separate file.
               The file name is generated by appending a suffix ending in
               .statistics to the source file name.  If the -option form is used,
               -stats will cause counters to be summed over the whole compilation
               unit while -details will dump every event as the passes generate
               them.  The default with no option is to sum counters for each
               function compiled.
    
           -fdump-tree-switch
           -fdump-tree-switch-options
               Control the dumping at various stages of processing the
               intermediate language tree to a file.  The file name is generated
               by appending a switch specific suffix to the source file name.  If
               the -options form is used, options is a list of - separated options
               that control the details of the dump.  Not all options are
               applicable to all dumps, those which are not meaningful will be
               ignored.  The following options are available
    
               address
                   Print the address of each node.  Usually this is not meaningful
                   as it changes according to the environment and source file.
                   Its primary use is for tying up a dump file with a debug
                   environment.
    
               slim
                   Inhibit dumping of members of a scope or body of a function
                   merely because that scope has been reached.  Only dump such
                   items when they are directly reachable by some other path.
                   When dumping pretty-printed trees, this option inhibits dumping
                   the bodies of control structures.
    
               raw Print a raw representation of the tree.  By default, trees are
                   pretty-printed into a C-like representation.
    
               details
                   Enable more detailed dumps (not honored by every dump option).
    
               stats
                   Enable dumping various statistics about the pass (not honored
                   by every dump option).
    
               blocks
                   Enable showing basic block boundaries (disabled in raw dumps).
    
               The following tree dumps are possible:
    
               original
                   Dump before any tree based optimization, to file.original.
    
               optimized
                   Dump after all tree based optimization, to file.optimized.
    
               gimple
                   Dump each function before and after the gimplification pass to
                   a file.  The file name is made by appending .gimple to the
                   source file name.
    
               cfg Dump the control flow graph of each function to a file.  The
                   file name is made by appending .cfg to the source file name.
    
               vcg Dump the control flow graph of each function to a file in VCG
                   format.  The file name is made by appending .vcg to the source
                   file name.  Note that if the file contains more than one
                   function, the generated file cannot be used directly by VCG.
                   You will need to cut and paste each function's graph into its
                   own separate file first.
    
               ch  Dump each function after copying loop headers.  The file name
                   is made by appending .ch to the source file name.
    
               ssa Dump SSA related information to a file.  The file name is made
                   by appending .ssa to the source file name.
    
               alias
                   Dump aliasing information for each function.  The file name is
                   made by appending .alias to the source file name.
    
               ccp Dump each function after CCP.  The file name is made by
                   appending .ccp to the source file name.
    
               storeccp
                   Dump each function after STORE-CCP.  The file name is made by
                   appending .storeccp to the source file name.
    
               pre Dump trees after partial redundancy elimination.  The file name
                   is made by appending .pre to the source file name.
    
               fre Dump trees after full redundancy elimination.  The file name is
                   made by appending .fre to the source file name.
    
               copyprop
                   Dump trees after copy propagation.  The file name is made by
                   appending .copyprop to the source file name.
    
               store_copyprop
                   Dump trees after store copy-propagation.  The file name is made
    
               sink
                   Dump each function after performing code sinking.  The file
                   name is made by appending .sink to the source file name.
    
               dom Dump each function after applying dominator tree optimizations.
                   The file name is made by appending .dom to the source file
                   name.
    
               dse Dump each function after applying dead store elimination.  The
                   file name is made by appending .dse to the source file name.
    
               phiopt
                   Dump each function after optimizing PHI nodes into straightline
                   code.  The file name is made by appending .phiopt to the source
                   file name.
    
               forwprop
                   Dump each function after forward propagating single use
                   variables.  The file name is made by appending .forwprop to the
                   source file name.
    
               copyrename
                   Dump each function after applying the copy rename optimization.
                   The file name is made by appending .copyrename to the source
                   file name.
    
               nrv Dump each function after applying the named return value
                   optimization on generic trees.  The file name is made by
                   appending .nrv to the source file name.
    
               vect
                   Dump each function after applying vectorization of loops.  The
                   file name is made by appending .vect to the source file name.
    
               vrp Dump each function after Value Range Propagation (VRP).  The
                   file name is made by appending .vrp to the source file name.
    
               all Enable all the available tree dumps with the flags provided in
                   this option.
    
           -ftree-vectorizer-verbose=n
               This option controls the amount of debugging output the vectorizer
               prints.  This information is written to standard error, unless
               -fdump-tree-all or -fdump-tree-vect is specified, in which case it
               is output to the usual dump listing file, .vect.  For n=0 no
               diagnostic information is reported.  If n=1 the vectorizer reports
               each loop that got vectorized, and the total number of loops that
               got vectorized.  If n=2 the vectorizer also reports non-vectorized
               loops that passed the first analysis phase (vect_analyze_loop_form)
               - i.e. countable, inner-most, single-bb, single-entry/exit loops.
               This is the same verbosity level that -fdump-tree-vect-stats uses.
               Higher verbosity levels mean either more information dumped for
               use random numbers.  It is used to generate certain symbol names
               that have to be different in every compiled file.  It is also used
               to place unique stamps in coverage data files and the object files
               that produce them.  You can use the -frandom-seed option to produce
               reproducibly identical object files.
    
               The string should be different for every file you compile.
    
           -fsched-verbose=n
               On targets that use instruction scheduling, this option controls
               the amount of debugging output the scheduler prints.  This
               information is written to standard error, unless -fdump-rtl-sched1
               or -fdump-rtl-sched2 is specified, in which case it is output to
               the usual dump listing file, .sched or .sched2 respectively.
               However for n greater than nine, the output is always printed to
               standard error.
    
               For n greater than zero, -fsched-verbose outputs the same
               information as -fdump-rtl-sched1 and -fdump-rtl-sched2.  For n
               greater than one, it also output basic block probabilities,
               detailed ready list information and unit/insn info.  For n greater
               than two, it includes RTL at abort point, control-flow and regions
               info.  And for n over four, -fsched-verbose also includes
               dependence info.
    
           -save-temps
               Store the usual "temporary" intermediate files permanently; place
               them in the current directory and name them based on the source
               file.  Thus, compiling foo.c with -c -save-temps would produce
               files foo.i and foo.s, as well as foo.o.  This creates a
               preprocessed foo.i output file even though the compiler now
               normally uses an integrated preprocessor.
    
               When used in combination with the -x command line option,
               -save-temps is sensible enough to avoid over writing an input
               source file with the same extension as an intermediate file.  The
               corresponding intermediate file may be obtained by renaming the
               source file before using -save-temps.
    
           -time[=file]
               Report the CPU time taken by each subprocess in the compilation
               sequence.  For C source files, this is the compiler proper and
               assembler (plus the linker if linking is done).
    
               Without the specification of an output file, the output looks like
               this:
    
                       # cc1 0.12 0.01
                       # as 0.00 0.01
    
               The first number on each line is the "user time", that is time
               spent executing the program itself.  The second number is "system
    
           -fvar-tracking
               Run variable tracking pass.  It computes where variables are stored
               at each position in code.  Better debugging information is then
               generated (if the debugging information format supports this
               information).
    
               It is enabled by default when compiling with optimization (-Os, -O,
               -O2, ...), debugging information (-g) and the debug info format
               supports it.
    
           -fvar-tracking-assignments
               Annotate assignments to user variables early in the compilation and
               attempt to carry the annotations over throughout the compilation
               all the way to the end, in an attempt to improve debug information
               while optimizing.
    
               It can be enabled even if var-tracking is disabled, in which case
               annotations will be created and maintained, but discarded at the
               end.
    
           -fvar-tracking-assignments-toggle
               Toggle -fvar-tracking-assignments, in the same way that -gtoggle
               toggles -g.
    
           -print-file-name=library
               Print the full absolute name of the library file library that would
               be used when linking---and don't do anything else.  With this
               option, GCC does not compile or link anything; it just prints the
               file name.
    
           -print-multi-directory
               Print the directory name corresponding to the multilib selected by
               any other switches present in the command line.  This directory is
               supposed to exist in GCC_EXEC_PREFIX.
    
           -print-multi-lib
               Print the mapping from multilib directory names to compiler
               switches that enable them.  The directory name is separated from
               the switches by ;, and each switch starts with an @} instead of the
               @samp{-, without spaces between multiple switches.  This is
               supposed to ease shell-processing.
    
           -print-multi-os-directory
               Print the path to OS libraries for the selected multilib, relative
               to some lib subdirectory.  If OS libraries are present in the lib
               subdirectory and no multilibs are used, this is usually just ., if
               OS libraries are present in libsuffix sibling directories this
               prints e.g. ../lib64, ../lib or ../lib32, or if OS libraries are
               present in lib/subdir subdirectories it prints e.g. amd64, sparcv9
               or ev6.
    
           -print-prog-name=program
    
               This is useful when gcc prints the error message installation
               problem, cannot exec cpp0: No such file or directory.  To resolve
               this you either need to put cpp0 and the other compiler components
               where gcc expects to find them, or you can set the environment
               variable GCC_EXEC_PREFIX to the directory where you installed them.
               Don't forget the trailing /.
    
           -print-sysroot
               Print the target sysroot directory that will be used during
               compilation.  This is the target sysroot specified either at
               configure time or using the --sysroot option, possibly with an
               extra suffix that depends on compilation options.  If no target
               sysroot is specified, the option prints nothing.
    
           -print-sysroot-headers-suffix
               Print the suffix added to the target sysroot when searching for
               headers, or give an error if the compiler is not configured with
               such a suffix---and don't do anything else.
    
           -dumpmachine
               Print the compiler's target machine (for example,
               i686-pc-linux-gnu)---and don't do anything else.
    
           -dumpversion
               Print the compiler version (for example, 3.0)---and don't do
               anything else.
    
           -dumpspecs
               Print the compiler's built-in specs---and don't do anything else.
               (This is used when GCC itself is being built.)
    
           -feliminate-unused-debug-types
               Normally, when producing DWARF2 output, GCC will emit debugging
               information for all types declared in a compilation unit,
               regardless of whether or not they are actually used in that
               compilation unit.  Sometimes this is useful, such as if, in the
               debugger, you want to cast a value to a type that is not actually
               used in your program (but is declared).  More often, however, this
               results in a significant amount of wasted space.  With this option,
               GCC will avoid producing debug symbol output for types that are
               nowhere used in the source file being compiled.
    
       Options That Control Optimization
           These options control various sorts of optimizations.
    
           Without any optimization option, the compiler's goal is to reduce the
           cost of compilation and to make debugging produce the expected results.
           Statements are independent: if you stop the program with a breakpoint
           between statements, you can then assign a new value to any variable or
           change the program counter to any other statement in the function and
           get exactly the results you would expect from the source code.
           -O1 Optimize.  Optimizing compilation takes somewhat more time, and a
               lot more memory for a large function.
    
               With -O, the compiler tries to reduce code size and execution time,
               without performing any optimizations that take a great deal of
               compilation time.
    
               -O turns on the following optimization flags:
    
               -fauto-inc-dec -fcprop-registers -fdce -fdefer-pop -fdelayed-branch
               -fdse -fguess-branch-probability -fif-conversion2 -fif-conversion
               -finline-small-functions -fipa-pure-const -fipa-reference
               -fmerge-constants -fsplit-wide-types -ftree-builtin-call-dce
               -ftree-ccp -ftree-ch -ftree-copyrename -ftree-dce
               -ftree-dominator-opts -ftree-dse -ftree-fre -ftree-sra -ftree-ter
               -funit-at-a-time
    
               -O also turns on -fomit-frame-pointer on machines where doing so
               does not interfere with debugging.
    
           -O2 Optimize even more.  GCC performs nearly all supported
               optimizations that do not involve a space-speed tradeoff.  As
               compared to -O, this option increases both compilation time and the
               performance of the generated code.
    
               -O2 turns on all optimization flags specified by -O.  It also turns
               on the following optimization flags: -fthread-jumps
               -falign-functions  -falign-jumps -falign-loops  -falign-labels
               -fcaller-saves -fcrossjumping -fcse-follow-jumps  -fcse-skip-blocks
               -fdelete-null-pointer-checks -fexpensive-optimizations -fgcse
               -fgcse-lm -findirect-inlining -foptimize-sibling-calls -fpeephole2
               -fregmove -freorder-blocks  -freorder-functions
               -frerun-cse-after-loop -fsched-interblock  -fsched-spec
               -fschedule-insns  -fschedule-insns2 -fstrict-aliasing
               -fstrict-overflow -ftree-switch-conversion -ftree-pre -ftree-vrp
    
               Please note the warning under -fgcse about invoking -O2 on programs
               that use computed gotos.
    
           -O3 Optimize yet more.  -O3 turns on all optimizations specified by -O2
               and also turns on the -finline-functions, -funswitch-loops,
               -fpredictive-commoning, -fgcse-after-reload, -ftree-vectorize and
               -fipa-cp-clone options.
    
           -O0 Reduce compilation time and make debugging produce the expected
               results.  This is the default.
    
           -Os Optimize for size.  -Os enables all -O2 optimizations that do not
               typically increase code size.  It also performs further
               optimizations designed to reduce code size.
    
               -Os disables the following optimization flags: -falign-functions
    
           activated by -O options or are related to ones that are.  You can use
           the following flags in the rare cases when "fine-tuning" of
           optimizations to be performed is desired.
    
           -fno-default-inline
               Do not make member functions inline by default merely because they
               are defined inside the class scope (C++ only).  Otherwise, when you
               specify -O, member functions defined inside class scope are
               compiled inline by default; i.e., you don't need to add inline in
               front of the member function name.
    
           -fno-defer-pop
               Always pop the arguments to each function call as soon as that
               function returns.  For machines which must pop arguments after a
               function call, the compiler normally lets arguments accumulate on
               the stack for several function calls and pops them all at once.
    
               Disabled at levels -O, -O2, -O3, -Os.
    
           -fforward-propagate
               Perform a forward propagation pass on RTL.  The pass tries to
               combine two instructions and checks if the result can be
               simplified.  If loop unrolling is active, two passes are performed
               and the second is scheduled after loop unrolling.
    
               This option is enabled by default at optimization levels -O2, -O3,
               -Os.
    
           -fomit-frame-pointer
               Don't keep the frame pointer in a register for functions that don't
               need one.  This avoids the instructions to save, set up and restore
               frame pointers; it also makes an extra register available in many
               functions.  It also makes debugging impossible on some machines.
    
               On some machines, such as the VAX, this flag has no effect, because
               the standard calling sequence automatically handles the frame
               pointer and nothing is saved by pretending it doesn't exist.  The
               machine-description macro "FRAME_POINTER_REQUIRED" controls whether
               a target machine supports this flag.
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -foptimize-sibling-calls
               Optimize sibling and tail recursive calls.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fno-inline
               Don't pay attention to the "inline" keyword.  Normally this option
               is used to keep the compiler from expanding any functions inline.
               Note that if you are not optimizing, no functions can be expanded
               inline.
    
               Enabled at level -O2.
    
           -finline-functions
               Integrate all simple functions into their callers.  The compiler
               heuristically decides which functions are simple enough to be worth
               integrating in this way.
    
               If all calls to a given function are integrated, and the function
               is declared "static", then the function is normally not output as
               assembler code in its own right.
    
               Enabled at level -O3.
    
           -finline-functions-called-once
               Consider all "static" functions called once for inlining into their
               caller even if they are not marked "inline".  If a call to a given
               function is integrated, then the function is not output as
               assembler code in its own right.
    
               Enabled at levels -O1, -O2, -O3 and -Os.
    
           -fearly-inlining
               Inline functions marked by "always_inline" and functions whose body
               seems smaller than the function call overhead early before doing
               -fprofile-generate instrumentation and real inlining pass.  Doing
               so makes profiling significantly cheaper and usually inlining
               faster on programs having large chains of nested wrapper functions.
    
               Enabled by default.
    
           -finline-limit=n
               By default, GCC limits the size of functions that can be inlined.
               This flag allows coarse control of this limit.  n is the size of
               functions that can be inlined in number of pseudo instructions.
    
               Inlining is actually controlled by a number of parameters, which
               may be specified individually by using --param name=value.  The
               -finline-limit=n option sets some of these parameters as follows:
    
               max-inline-insns-single
                   is set to n/2.
    
               max-inline-insns-auto
                   is set to n/2.
    
               See below for a documentation of the individual parameters
               controlling inlining and for the defaults of these parameters.
    
               Note: there may be no value to -finline-limit that results in
               default behavior.
    
               turned on, even if the variables aren't referenced.
    
               GCC enables this option by default.  If you want to force the
               compiler to check if the variable was referenced, regardless of
               whether or not optimization is turned on, use the
               -fno-keep-static-consts option.
    
           -fmerge-constants
               Attempt to merge identical constants (string constants and floating
               point constants) across compilation units.
    
               This option is the default for optimized compilation if the
               assembler and linker support it.  Use -fno-merge-constants to
               inhibit this behavior.
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -fmerge-all-constants
               Attempt to merge identical constants and identical variables.
    
               This option implies -fmerge-constants.  In addition to
               -fmerge-constants this considers e.g. even constant initialized
               arrays or initialized constant variables with integral or floating
               point types.  Languages like C or C++ require each variable,
               including multiple instances of the same variable in recursive
               calls, to have distinct locations, so using this option will result
               in non-conforming behavior.
    
           -fmodulo-sched
               Perform swing modulo scheduling immediately before the first
               scheduling pass.  This pass looks at innermost loops and reorders
               their instructions by overlapping different iterations.
    
           -fmodulo-sched-allow-regmoves
               Perform more aggressive SMS based modulo scheduling with register
               moves allowed.  By setting this flag certain anti-dependences edges
               will be deleted which will trigger the generation of reg-moves
               based on the life-range analysis.  This option is effective only
               with -fmodulo-sched enabled.
    
           -fno-branch-count-reg
               Do not use "decrement and branch" instructions on a count register,
               but instead generate a sequence of instructions that decrement a
               register, compare it against zero, then branch based upon the
               result.  This option is only meaningful on architectures that
               support such instructions, which include x86, PowerPC, IA-64 and
               S/390.
    
               The default is -fbranch-count-reg.
    
           -fno-function-cse
               Do not put function addresses in registers; make each instruction
               This option turns off this behavior because some programs
               explicitly rely on variables going to the data section.  E.g., so
               that the resulting executable can find the beginning of that
               section and/or make assumptions based on that.
    
               The default is -fzero-initialized-in-bss.
    
           -fmudflap -fmudflapth -fmudflapir
               For front-ends that support it (C and C++), instrument all risky
               pointer/array dereferencing operations, some standard library
               string/heap functions, and some other associated constructs with
               range/validity tests.  Modules so instrumented should be immune to
               buffer overflows, invalid heap use, and some other classes of C/C++
               programming errors.  The instrumentation relies on a separate
               runtime library (libmudflap), which will be linked into a program
               if -fmudflap is given at link time.  Run-time behavior of the
               instrumented program is controlled by the MUDFLAP_OPTIONS
               environment variable.  See "env MUDFLAP_OPTIONS=-help a.out" for
               its options.
    
               Use -fmudflapth instead of -fmudflap to compile and to link if your
               program is multi-threaded.  Use -fmudflapir, in addition to
               -fmudflap or -fmudflapth, if instrumentation should ignore pointer
               reads.  This produces less instrumentation (and therefore faster
               execution) and still provides some protection against outright
               memory corrupting writes, but allows erroneously read data to
               propagate within a program.
    
           -fthread-jumps
               Perform optimizations where we check to see if a jump branches to a
               location where another comparison subsumed by the first is found.
               If so, the first branch is redirected to either the destination of
               the second branch or a point immediately following it, depending on
               whether the condition is known to be true or false.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fsplit-wide-types
               When using a type that occupies multiple registers, such as "long
               long" on a 32-bit system, split the registers apart and allocate
               them independently.  This normally generates better code for those
               types, but may make debugging more difficult.
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -fcse-follow-jumps
               In common subexpression elimination (CSE), scan through jump
               instructions when the target of the jump is not reached by any
               other path.  For example, when CSE encounters an "if" statement
               with an "else" clause, CSE will follow the jump when the condition
               tested is false.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fgcse
               Perform a global common subexpression elimination pass.  This pass
               also performs global constant and copy propagation.
    
               Note: When compiling a program using computed gotos, a GCC
               extension, you may get better runtime performance if you disable
               the global common subexpression elimination pass by adding
               -fno-gcse to the command line.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fgcse-lm
               When -fgcse-lm is enabled, global common subexpression elimination
               will attempt to move loads which are only killed by stores into
               themselves.  This allows a loop containing a load/store sequence to
               be changed to a load outside the loop, and a copy/store within the
               loop.
    
               Enabled by default when gcse is enabled.
    
           -fgcse-sm
               When -fgcse-sm is enabled, a store motion pass is run after global
               common subexpression elimination.  This pass will attempt to move
               stores out of loops.  When used in conjunction with -fgcse-lm,
               loops containing a load/store sequence can be changed to a load
               before the loop and a store after the loop.
    
               Not enabled at any optimization level.
    
           -fgcse-las
               When -fgcse-las is enabled, the global common subexpression
               elimination pass eliminates redundant loads that come after stores
               to the same memory location (both partial and full redundancies).
    
               Not enabled at any optimization level.
    
           -fgcse-after-reload
               When -fgcse-after-reload is enabled, a redundant load elimination
               pass is performed after reload.  The purpose of this pass is to
               cleanup redundant spilling.
    
           -funsafe-loop-optimizations
               If given, the loop optimizer will assume that loop indices do not
               overflow, and that the loops with nontrivial exit condition are not
               infinite.  This enables a wider range of loop optimizations even if
               the loop optimizer itself cannot prove that these assumptions are
               valid.  Using -Wunsafe-loop-optimizations, the compiler will warn
               you if it finds this kind of loop.
    
           -fcrossjumping
               -O and higher.
    
           -fdse
               Perform dead store elimination (DSE) on RTL.  Enabled by default at
               -O and higher.
    
           -fif-conversion
               Attempt to transform conditional jumps into branch-less
               equivalents.  This include use of conditional moves, min, max, set
               flags and abs instructions, and some tricks doable by standard
               arithmetics.  The use of conditional execution on chips where it is
               available is controlled by "if-conversion2".
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -fif-conversion2
               Use conditional execution (where available) to transform
               conditional jumps into branch-less equivalents.
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -fdelete-null-pointer-checks
               Use global dataflow analysis to identify and eliminate useless
               checks for null pointers.  The compiler assumes that dereferencing
               a null pointer would have halted the program.  If a pointer is
               checked after it has already been dereferenced, it cannot be null.
    
               In some environments, this assumption is not true, and programs can
               safely dereference null pointers.  Use
               -fno-delete-null-pointer-checks to disable this optimization for
               programs which depend on that behavior.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fexpensive-optimizations
               Perform a number of minor optimizations that are relatively
               expensive.
    
               Enabled at levels -O2, -O3, -Os.
    
           -foptimize-register-move
           -fregmove
               Attempt to reassign register numbers in move instructions and as
               operands of other simple instructions in order to maximize the
               amount of register tying.  This is especially helpful on machines
               with two-operand instructions.
    
               Note -fregmove and -foptimize-register-move are the same
               optimization.
    
               Enabled at levels -O2, -O3, -Os.
    
               for loops with small register pressure as the regions, and third
               one means using all function as a single region.  The first value
               can give best result for machines with small size and irregular
               register set, the third one results in faster and generates decent
               code and the smallest size code, and the default value usually give
               the best results in most cases and for most architectures.
    
           -fira-coalesce
               Do optimistic register coalescing.  This option might be profitable
               for architectures with big regular register files.
    
           -fno-ira-share-save-slots
               Switch off sharing stack slots used for saving call used hard
               registers living through a call.  Each hard register will get a
               separate stack slot and as a result function stack frame will be
               bigger.
    
           -fno-ira-share-spill-slots
               Switch off sharing stack slots allocated for pseudo-registers.
               Each pseudo-register which did not get a hard register will get a
               separate stack slot and as a result function stack frame will be
               bigger.
    
           -fira-verbose=n
               Set up how verbose dump file for the integrated register allocator
               will be.  Default value is 5.  If the value is greater or equal to
               10, the dump file will be stderr as if the value were n minus 10.
    
           -fdelayed-branch
               If supported for the target machine, attempt to reorder
               instructions to exploit instruction slots available after delayed
               branch instructions.
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -fschedule-insns
               If supported for the target machine, attempt to reorder
               instructions to eliminate execution stalls due to required data
               being unavailable.  This helps machines that have slow floating
               point or memory load instructions by allowing other instructions to
               be issued until the result of the load or floating point
               instruction is required.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fschedule-insns2
               Similar to -fschedule-insns, but requests an additional pass of
               instruction scheduling after register allocation has been done.
               This is especially useful on machines with a relatively small
               number of registers and where memory load instructions take more
               than one cycle.
    
               makes sense when scheduling before register allocation, i.e. with
               -fschedule-insns or at -O2 or higher.
    
           -fsched-spec-load-dangerous
               Allow speculative motion of more load instructions.  This only
               makes sense when scheduling before register allocation, i.e. with
               -fschedule-insns or at -O2 or higher.
    
           -fsched-stalled-insns
           -fsched-stalled-insns=n
               Define how many insns (if any) can be moved prematurely from the
               queue of stalled insns into the ready list, during the second
               scheduling pass.  -fno-sched-stalled-insns means that no insns will
               be moved prematurely, -fsched-stalled-insns=0 means there is no
               limit on how many queued insns can be moved prematurely.
               -fsched-stalled-insns without a value is equivalent to
               -fsched-stalled-insns=1.
    
           -fsched-stalled-insns-dep
           -fsched-stalled-insns-dep=n
               Define how many insn groups (cycles) will be examined for a
               dependency on a stalled insn that is candidate for premature
               removal from the queue of stalled insns.  This has an effect only
               during the second scheduling pass, and only if
               -fsched-stalled-insns is used.  -fno-sched-stalled-insns-dep is
               equivalent to -fsched-stalled-insns-dep=0.
               -fsched-stalled-insns-dep without a value is equivalent to
               -fsched-stalled-insns-dep=1.
    
           -fsched2-use-superblocks
               When scheduling after register allocation, do use superblock
               scheduling algorithm.  Superblock scheduling allows motion across
               basic block boundaries resulting on faster schedules.  This option
               is experimental, as not all machine descriptions used by GCC model
               the CPU closely enough to avoid unreliable results from the
               algorithm.
    
               This only makes sense when scheduling after register allocation,
               i.e. with -fschedule-insns2 or at -O2 or higher.
    
           -fsched2-use-traces
               Use -fsched2-use-superblocks algorithm when scheduling after
               register allocation and additionally perform code duplication in
               order to increase the size of superblocks using tracer pass.  See
               -ftracer for details on trace formation.
    
               This mode should produce faster but significantly longer programs.
               Also without -fbranch-probabilities the traces constructed may not
               match the reality and hurt the performance.  This only makes sense
               when scheduling after register allocation, i.e. with
               -fschedule-insns2 or at -O2 or higher.
    
           -fselective-scheduling2
               Schedule instructions using selective scheduling algorithm.
               Selective scheduling runs instead of the second scheduler pass.
    
           -fsel-sched-pipelining
               Enable software pipelining of innermost loops during selective
               scheduling.  This option has no effect until one of
               -fselective-scheduling or -fselective-scheduling2 is turned on.
    
           -fsel-sched-pipelining-outer-loops
               When pipelining loops during selective scheduling, also pipeline
               outer loops.  This option has no effect until
               -fsel-sched-pipelining is turned on.
    
           -fcaller-saves
               Enable values to be allocated in registers that will be clobbered
               by function calls, by emitting extra instructions to save and
               restore the registers around such calls.  Such allocation is done
               only when it seems to result in better code than would otherwise be
               produced.
    
               This option is always enabled by default on certain machines,
               usually those which have no call-preserved registers to use
               instead.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fconserve-stack
               Attempt to minimize stack usage.  The compiler will attempt to use
               less stack space, even if that makes the program slower.  This
               option implies setting the large-stack-frame parameter to 100 and
               the large-stack-frame-growth parameter to 400.
    
           -ftree-reassoc
               Perform reassociation on trees.  This flag is enabled by default at
               -O and higher.
    
           -ftree-pre
               Perform partial redundancy elimination (PRE) on trees.  This flag
               is enabled by default at -O2 and -O3.
    
           -ftree-fre
               Perform full redundancy elimination (FRE) on trees.  The difference
               between FRE and PRE is that FRE only considers expressions that are
               computed on all paths leading to the redundant computation.  This
               analysis is faster than PRE, though it exposes fewer redundancies.
               This flag is enabled by default at -O and higher.
    
           -ftree-copy-prop
               Perform copy propagation on trees.  This pass eliminates
               unnecessary copy operations.  This flag is enabled by default at -O
               and higher.
               (enabled with -fprofile-generate) or static (which uses built-in
               heuristics).  Require -fipa-type-escape to provide the safety of
               this transformation.  It works only in whole program mode, so it
               requires -fwhole-program and -combine to be enabled.  Structures
               considered cold by this transformation are not affected (see
               --param struct-reorg-cold-struct-ratio=value).
    
               With this flag, the program debug info reflects a new structure
               layout.
    
           -fipa-pta
               Perform interprocedural pointer analysis.  This option is
               experimental and does not affect generated code.
    
           -fipa-cp
               Perform interprocedural constant propagation.  This optimization
               analyzes the program to determine when values passed to functions
               are constants and then optimizes accordingly.  This optimization
               can substantially increase performance if the application has
               constants passed to functions.  This flag is enabled by default at
               -O2, -Os and -O3.
    
           -fipa-cp-clone
               Perform function cloning to make interprocedural constant
               propagation stronger.  When enabled, interprocedural constant
               propagation will perform function cloning when externally visible
               function can be called with constant arguments.  Because this
               optimization can create multiple copies of functions, it may
               significantly increase code size (see --param
               ipcp-unit-growth=value).  This flag is enabled by default at -O3.
    
           -fipa-matrix-reorg
               Perform matrix flattening and transposing.  Matrix flattening tries
               to replace a m-dimensional matrix with its equivalent n-dimensional
               matrix, where n < m.  This reduces the level of indirection needed
               for accessing the elements of the matrix. The second optimization
               is matrix transposing that attempts to change the order of the
               matrix's dimensions in order to improve cache locality.  Both
               optimizations need the -fwhole-program flag.  Transposing is
               enabled only if profiling information is available.
    
           -ftree-sink
               Perform forward store motion  on trees.  This flag is enabled by
               default at -O and higher.
    
           -ftree-ccp
               Perform sparse conditional constant propagation (CCP) on trees.
               This pass only operates on local scalar variables and is enabled by
               default at -O and higher.
    
           -ftree-switch-conversion
               Perform conversion of simple initializations in a switch to
               Perform a variety of simple scalar cleanups (constant/copy
               propagation, redundancy elimination, range propagation and
               expression simplification) based on a dominator tree traversal.
               This also performs jump threading (to reduce jumps to jumps). This
               flag is enabled by default at -O and higher.
    
           -ftree-dse
               Perform dead store elimination (DSE) on trees.  A dead store is a
               store into a memory location which will later be overwritten by
               another store without any intervening loads.  In this case the
               earlier store can be deleted.  This flag is enabled by default at
               -O and higher.
    
           -ftree-ch
               Perform loop header copying on trees.  This is beneficial since it
               increases effectiveness of code motion optimizations.  It also
               saves one jump.  This flag is enabled by default at -O and higher.
               It is not enabled for -Os, since it usually increases code size.
    
           -ftree-loop-optimize
               Perform loop optimizations on trees.  This flag is enabled by
               default at -O and higher.
    
           -ftree-loop-linear
               Perform linear loop transformations on tree.  This flag can improve
               cache performance and allow further loop optimizations to take
               place.
    
           -floop-interchange
               Perform loop interchange transformations on loops.  Interchanging
               two nested loops switches the inner and outer loops.  For example,
               given a loop like:
    
                       DO J = 1, M
                         DO I = 1, N
                           A(J, I) = A(J, I) * C
                         ENDDO
                       ENDDO
    
               loop interchange will transform the loop as if the user had
               written:
    
                       DO I = 1, N
                         DO J = 1, M
                           A(J, I) = A(J, I) * C
                         ENDDO
                       ENDDO
    
               which can be beneficial when "N" is larger than the caches, because
               in Fortran, the elements of an array are stored in memory
               contiguously by column, and the original loop iterates over rows,
               potentially creating at each access a cache miss.  This
    
               loop strip mining will transform the loop as if the user had
               written:
    
                       DO II = 1, N, 4
                         DO I = II, min (II + 3, N)
                           A(I) = A(I) + C
                         ENDDO
                       ENDDO
    
               This optimization applies to all the languages supported by GCC and
               is not limited to Fortran.  To use this code transformation, GCC
               has to be configured with --with-ppl and --with-cloog to enable the
               Graphite loop transformation infrastructure.
    
           -floop-block
               Perform loop blocking transformations on loops.  Blocking strip
               mines each loop in the loop nest such that the memory accesses of
               the element loops fit inside caches.  For example, given a loop
               like:
    
                       DO I = 1, N
                         DO J = 1, M
                           A(J, I) = B(I) + C(J)
                         ENDDO
                       ENDDO
    
               loop blocking will transform the loop as if the user had written:
    
                       DO II = 1, N, 64
                         DO JJ = 1, M, 64
                           DO I = II, min (II + 63, N)
                             DO J = JJ, min (JJ + 63, M)
                               A(J, I) = B(I) + C(J)
                             ENDDO
                           ENDDO
                         ENDDO
                       ENDDO
    
               which can be beneficial when "M" is larger than the caches, because
               the innermost loop will iterate over a smaller amount of data that
               can be kept in the caches.  This optimization applies to all the
               languages supported by GCC and is not limited to Fortran.  To use
               this code transformation, GCC has to be configured with --with-ppl
               and --with-cloog to enable the Graphite loop transformation
               infrastructure.
    
           -fcheck-data-deps
               Compare the results of several data dependence analyzers.  This
               option is used for debugging the data dependence analyzers.
    
           -ftree-loop-distribution
                       ENDDO
                       DO I = 1, N
                          D(I) = E(I) * F
                       ENDDO
    
           -ftree-loop-im
               Perform loop invariant motion on trees.  This pass moves only
               invariants that would be hard to handle at RTL level (function
               calls, operations that expand to nontrivial sequences of insns).
               With -funswitch-loops it also moves operands of conditions that are
               invariant out of the loop, so that we can use just trivial
               invariantness analysis in loop unswitching.  The pass also includes
               store motion.
    
           -ftree-loop-ivcanon
               Create a canonical counter for number of iterations in the loop for
               that determining number of iterations requires complicated
               analysis.  Later optimizations then may determine the number
               easily.  Useful especially in connection with unrolling.
    
           -fivopts
               Perform induction variable optimizations (strength reduction,
               induction variable merging and induction variable elimination) on
               trees.
    
           -ftree-parallelize-loops=n
               Parallelize loops, i.e., split their iteration space to run in n
               threads.  This is only possible for loops whose iterations are
               independent and can be arbitrarily reordered.  The optimization is
               only profitable on multiprocessor machines, for loops that are CPU-
               intensive, rather than constrained e.g. by memory bandwidth.  This
               option implies -pthread, and thus is only supported on targets that
               have support for -pthread.
    
           -ftree-sra
               Perform scalar replacement of aggregates.  This pass replaces
               structure references with scalars to prevent committing structures
               to memory too early.  This flag is enabled by default at -O and
               higher.
    
           -ftree-copyrename
               Perform copy renaming on trees.  This pass attempts to rename
               compiler temporaries to other variables at copy locations, usually
               resulting in variable names which more closely resemble the
               original variables.  This flag is enabled by default at -O and
               higher.
    
           -ftree-coalesce-inlined-vars
               Permit the copyrename pass to subject inlined variables to
               coalescing into other variables.  This may harm debug information
               of such inlined variables, but it will keep variables of the main
               function apart from each other, such that they are more likely to
               work on resulting in better RTL generation.  This is enabled by
               default at -O and higher.
    
           -ftree-vectorize
               Perform loop vectorization on trees. This flag is enabled by
               default at -O3.
    
           -ftree-vect-loop-version
               Perform loop versioning when doing loop vectorization on trees.
               When a loop appears to be vectorizable except that data alignment
               or data dependence cannot be determined at compile time then
               vectorized and non-vectorized versions of the loop are generated
               along with runtime checks for alignment or dependence to control
               which version is executed.  This option is enabled by default
               except at level -Os where it is disabled.
    
           -fvect-cost-model
               Enable cost model for vectorization.
    
           -ftree-vrp
               Perform Value Range Propagation on trees.  This is similar to the
               constant propagation pass, but instead of values, ranges of values
               are propagated.  This allows the optimizers to remove unnecessary
               range checks like array bound checks and null pointer checks.  This
               is enabled by default at -O2 and higher.  Null pointer check
               elimination is only done if -fdelete-null-pointer-checks is
               enabled.
    
           -ftracer
               Perform tail duplication to enlarge superblock size.  This
               transformation simplifies the control flow of the function allowing
               other optimizations to do better job.
    
           -funroll-loops
               Unroll loops whose number of iterations can be determined at
               compile time or upon entry to the loop.  -funroll-loops implies
               -frerun-cse-after-loop.  This option makes code larger, and may or
               may not make it run faster.
    
           -funroll-all-loops
               Unroll all loops, even if their number of iterations is uncertain
               when the loop is entered.  This usually makes programs run more
               slowly.  -funroll-all-loops implies the same options as
               -funroll-loops,
    
           -fsplit-ivs-in-unroller
               Enables expressing of values of induction variables in later
               iterations of the unrolled loop using the value in the first
               iteration.  This breaks long dependency chains, thus improving
               efficiency of the scheduling passes.
    
               Combination of -fweb and CSE is often sufficient to obtain the same
               computations (especially memory loads and stores) performed in
               previous iterations of loops.
    
               This option is enabled at level -O3.
    
           -fprefetch-loop-arrays
               If supported by the target machine, generate instructions to
               prefetch memory to improve the performance of loops that access
               large arrays.
    
               This option may generate better or worse code; results are highly
               dependent on the structure of loops within the source code.
    
               Disabled at level -Os.
    
           -fno-peephole
           -fno-peephole2
               Disable any machine-specific peephole optimizations.  The
               difference between -fno-peephole and -fno-peephole2 is in how they
               are implemented in the compiler; some targets use one, some use the
               other, a few use both.
    
               -fpeephole is enabled by default.  -fpeephole2 enabled at levels
               -O2, -O3, -Os.
    
           -fno-guess-branch-probability
               Do not guess branch probabilities using heuristics.
    
               GCC will use heuristics to guess branch probabilities if they are
               not provided by profiling feedback (-fprofile-arcs).  These
               heuristics are based on the control flow graph.  If some branch
               probabilities are specified by __builtin_expect, then the
               heuristics will be used to guess branch probabilities for the rest
               of the control flow graph, taking the __builtin_expect info into
               account.  The interactions between the heuristics and
               __builtin_expect can be complex, and in some cases, it may be
               useful to disable the heuristics so that the effects of
               __builtin_expect are easier to understand.
    
               The default is -fguess-branch-probability at levels -O, -O2, -O3,
               -Os.
    
           -freorder-blocks
               Reorder basic blocks in the compiled function in order to reduce
               number of taken branches and improve code locality.
    
               Enabled at levels -O2, -O3.
    
           -freorder-blocks-and-partition
               In addition to reordering basic blocks in the compiled function, in
               order to reduce number of taken branches, partitions hot and cold
               basic blocks into separate sections of the assembly and .o files,
    
               Also profile feedback must be available in to make this option
               effective.  See -fprofile-arcs for details.
    
               Enabled at levels -O2, -O3, -Os.
    
           -fstrict-aliasing
               Allow the compiler to assume the strictest aliasing rules
               applicable to the language being compiled.  For C (and C++), this
               activates optimizations based on the type of expressions.  In
               particular, an object of one type is assumed never to reside at the
               same address as an object of a different type, unless the types are
               almost the same.  For example, an "unsigned int" can alias an
               "int", but not a "void*" or a "double".  A character type may alias
               any other type.
    
               Pay special attention to code like this:
    
                       union a_union {
                         int i;
                         double d;
                       };
    
                       int f() {
                         union a_union t;
                         t.d = 3.0;
                         return t.i;
                       }
    
               The practice of reading from a different union member than the one
               most recently written to (called "type-punning") is common.  Even
               with -fstrict-aliasing, type-punning is allowed, provided the
               memory is accessed through the union type.  So, the code above will
               work as expected.    However, this code might not:
    
                       int f() {
                         union a_union t;
                         int* ip;
                         t.d = 3.0;
                         ip = &t.i;
                         return *ip;
                       }
    
               Similarly, access by taking the address, casting the resulting
               pointer and dereferencing the result has undefined behavior, even
               if the cast uses a union type, e.g.:
    
                       int f() {
                         double d = 3.0;
                         return ((union a_union *) &d)->i;
                       }
    
               actually involve overflow.
    
               This option also allows the compiler to assume strict pointer
               semantics: given a pointer to an object, if adding an offset to
               that pointer does not produce a pointer to the same object, the
               addition is undefined.  This permits the compiler to conclude that
               "p + u > p" is always true for a pointer "p" and unsigned integer
               "u".  This assumption is only valid because pointer wraparound is
               undefined, as the expression is false if "p + u" overflows using
               twos complement arithmetic.
    
               See also the -fwrapv option.  Using -fwrapv means that integer
               signed overflow is fully defined: it wraps.  When -fwrapv is used,
               there is no difference between -fstrict-overflow and
               -fno-strict-overflow for integers.  With -fwrapv certain types of
               overflow are permitted.  For example, if the compiler gets an
               overflow when doing arithmetic on constants, the overflowed value
               can still be used with -fwrapv, but not otherwise.
    
               The -fstrict-overflow option is enabled at levels -O2, -O3, -Os.
    
           -falign-functions
           -falign-functions=n
               Align the start of functions to the next power-of-two greater than
               n, skipping up to n bytes.  For instance, -falign-functions=32
               aligns functions to the next 32-byte boundary, but
               -falign-functions=24 would align to the next 32-byte boundary only
               if this can be done by skipping 23 bytes or less.
    
               -fno-align-functions and -falign-functions=1 are equivalent and
               mean that functions will not be aligned.
    
               Some assemblers only support this flag when n is a power of two; in
               that case, it is rounded up.
    
               If n is not specified or is zero, use a machine-dependent default.
    
               Enabled at levels -O2, -O3.
    
           -falign-labels
           -falign-labels=n
               Align all branch targets to a power-of-two boundary, skipping up to
               n bytes like -falign-functions.  This option can easily make code
               slower, because it must insert dummy operations for when the branch
               target is reached in the usual flow of the code.
    
               -fno-align-labels and -falign-labels=1 are equivalent and mean that
               labels will not be aligned.
    
               If -falign-loops or -falign-jumps are applicable and are greater
               than this value, then their values are used instead.
    
    
               If n is not specified or is zero, use a machine-dependent default.
    
               Enabled at levels -O2, -O3.
    
           -falign-jumps
           -falign-jumps=n
               Align branch targets to a power-of-two boundary, for branch targets
               where the targets can only be reached by jumping, skipping up to n
               bytes like -falign-functions.  In this case, no dummy operations
               need be executed.
    
               -fno-align-jumps and -falign-jumps=1 are equivalent and mean that
               loops will not be aligned.
    
               If n is not specified or is zero, use a machine-dependent default.
    
               Enabled at levels -O2, -O3.
    
           -funit-at-a-time
               This option is left for compatibility reasons. -funit-at-a-time has
               no effect, while -fno-unit-at-a-time implies -fno-toplevel-reorder
               and -fno-section-anchors.
    
               Enabled by default.
    
           -fno-toplevel-reorder
               Do not reorder top-level functions, variables, and "asm"
               statements.  Output them in the same order that they appear in the
               input file.  When this option is used, unreferenced static
               variables will not be removed.  This option is intended to support
               existing code which relies on a particular ordering.  For new code,
               it is better to use attributes.
    
               Enabled at level -O0.  When disabled explicitly, it also imply
               -fno-section-anchors that is otherwise enabled at -O0 on some
               targets.
    
           -fweb
               Constructs webs as commonly used for register allocation purposes
               and assign each web individual pseudo register.  This allows the
               register allocation pass to operate on pseudos directly, but also
               strengthens several other optimization passes, such as CSE, loop
               optimizer and trivial dead code remover.  It can, however, make
               debugging impossible, since variables will no longer stay in a
               "home register".
    
               Enabled by default with -funroll-loops.
    
           -fwhole-program
               Assume that the current compilation unit represents whole program
               being compiled.  All public functions and variables with the
               splitting, we perform a copy-propagation pass to try to reduce
               scheduling dependencies and occasionally eliminate the copy.
    
               Enabled at levels -O, -O2, -O3, -Os.
    
           -fprofile-correction
               Profiles collected using an instrumented binary for multi-threaded
               programs may be inconsistent due to missed counter updates. When
               this option is specified, GCC will use heuristics to correct or
               smooth out such inconsistencies. By default, GCC will emit an error
               message when an inconsistent profile is detected.
    
           -fprofile-dir=path
               Set the directory to search the profile data files in to path.
               This option affects only the profile data generated by
               -fprofile-generate, -ftest-coverage, -fprofile-arcs and used by
               -fprofile-use and -fbranch-probabilities and its related options.
               By default, GCC will use the current directory as path thus the
               profile data file will appear in the same directory as the object
               file.
    
           -fprofile-generate
           -fprofile-generate=path
               Enable options usually used for instrumenting application to
               produce profile useful for later recompilation with profile
               feedback based optimization.  You must use -fprofile-generate both
               when compiling and when linking your program.
    
               The following options are enabled: "-fprofile-arcs",
               "-fprofile-values", "-fvpt".
    
               If path is specified, GCC will look at the path to find the profile
               feedback data files. See -fprofile-dir.
    
           -fprofile-use
           -fprofile-use=path
               Enable profile feedback directed optimizations, and optimizations
               generally profitable only with profile feedback available.
    
               The following options are enabled: "-fbranch-probabilities",
               "-fvpt", "-funroll-loops", "-fpeel-loops", "-ftracer"
    
               By default, GCC emits an error message if the feedback profiles do
               not match the source code.  This error can be turned into a warning
               by using -Wcoverage-mismatch.  Note this may result in poorly
               optimized code.
    
               If path is specified, GCC will look at the path to find the profile
               feedback data files. See -fprofile-dir.
    
           The following options control compiler behavior regarding floating
           point arithmetic.  These options trade off between speed and
               into variables.
    
           -ffast-math
               Sets -fno-math-errno, -funsafe-math-optimizations,
               -ffinite-math-only, -fno-rounding-math, -fno-signaling-nans and
               -fcx-limited-range.
    
               This option causes the preprocessor macro "__FAST_MATH__" to be
               defined.
    
               This option is not turned on by any -O option since it can result
               in incorrect output for programs which depend on an exact
               implementation of IEEE or ISO rules/specifications for math
               functions. It may, however, yield faster code for programs that do
               not require the guarantees of these specifications.
    
           -fno-math-errno
               Do not set ERRNO after calling math functions that are executed
               with a single instruction, e.g., sqrt.  A program that relies on
               IEEE exceptions for math error handling may want to use this flag
               for speed while maintaining IEEE arithmetic compatibility.
    
               This option is not turned on by any -O option since it can result
               in incorrect output for programs which depend on an exact
               implementation of IEEE or ISO rules/specifications for math
               functions. It may, however, yield faster code for programs that do
               not require the guarantees of these specifications.
    
               The default is -fmath-errno.
    
               On Darwin systems, the math library never sets "errno".  There is
               therefore no reason for the compiler to consider the possibility
               that it might, and -fno-math-errno is the default.
    
           -funsafe-math-optimizations
               Allow optimizations for floating-point arithmetic that (a) assume
               that arguments and results are valid and (b) may violate IEEE or
               ANSI standards.  When used at link-time, it may include libraries
               or startup files that change the default FPU control word or other
               similar optimizations.
    
               This option is not turned on by any -O option since it can result
               in incorrect output for programs which depend on an exact
               implementation of IEEE or ISO rules/specifications for math
               functions. It may, however, yield faster code for programs that do
               not require the guarantees of these specifications.  Enables
               -fno-signed-zeros, -fno-trapping-math, -fassociative-math and
               -freciprocal-math.
    
               The default is -fno-unsafe-math-optimizations.
    
           -fassociative-math
               Allow the reciprocal of a value to be used instead of dividing by
               the value if this enables optimizations.  For example "x / y" can
               be replaced with "x * (1/y)" which is useful if "(1/y)" is subject
               to common subexpression elimination.  Note that this loses
               precision and increases the number of flops operating on the value.
    
               The default is -fno-reciprocal-math.
    
           -ffinite-math-only
               Allow optimizations for floating-point arithmetic that assume that
               arguments and results are not NaNs or +-Infs.
    
               This option is not turned on by any -O option since it can result
               in incorrect output for programs which depend on an exact
               implementation of IEEE or ISO rules/specifications for math
               functions. It may, however, yield faster code for programs that do
               not require the guarantees of these specifications.
    
               The default is -fno-finite-math-only.
    
           -fno-signed-zeros
               Allow optimizations for floating point arithmetic that ignore the
               signedness of zero.  IEEE arithmetic specifies the behavior of
               distinct +0.0 and -0.0 values, which then prohibits simplification
               of expressions such as x+0.0 or 0.0*x (even with
               -ffinite-math-only).  This option implies that the sign of a zero
               result isn't significant.
    
               The default is -fsigned-zeros.
    
           -fno-trapping-math
               Compile code assuming that floating-point operations cannot
               generate user-visible traps.  These traps include division by zero,
               overflow, underflow, inexact result and invalid operation.  This
               option requires that -fno-signaling-nans be in effect.  Setting
               this option may allow faster code if one relies on "non-stop" IEEE
               arithmetic, for example.
    
               This option should never be turned on by any -O option since it can
               result in incorrect output for programs which depend on an exact
               implementation of IEEE or ISO rules/specifications for math
               functions.
    
               The default is -ftrapping-math.
    
           -frounding-math
               Disable transformations and optimizations that assume default
               floating point rounding behavior.  This is round-to-zero for all
               floating point to integer conversions, and round-to-nearest for all
               other arithmetic truncations.  This option should be specified for
               programs that change the FP rounding mode dynamically, or that may
               be executed with a non-default rounding mode.  This option disables
               It is a size optimization method. This option is to find identical
               sequences of code, which can be turned into pseudo-procedures  and
               then  replace  all  occurrences with  calls to  the  newly created
               subroutine. It is kind of an opposite of -finline-functions.  This
               optimization runs at RTL level.
    
           -fsignaling-nans
               Compile code assuming that IEEE signaling NaNs may generate user-
               visible traps during floating-point operations.  Setting this
               option disables optimizations that may change the number of
               exceptions visible with signaling NaNs.  This option implies
               -ftrapping-math.
    
               This option causes the preprocessor macro "__SUPPORT_SNAN__" to be
               defined.
    
               The default is -fno-signaling-nans.
    
               This option is experimental and does not currently guarantee to
               disable all GCC optimizations that affect signaling NaN behavior.
    
           -fsingle-precision-constant
               Treat floating point constant as single precision constant instead
               of implicitly converting it to double precision constant.
    
           -fcx-limited-range
               When enabled, this option states that a range reduction step is not
               needed when performing complex division.  Also, there is no
               checking whether the result of a complex multiplication or division
               is "NaN + I*NaN", with an attempt to rescue the situation in that
               case.  The default is -fno-cx-limited-range, but is enabled by
               -ffast-math.
    
               This option controls the default setting of the ISO C99
               "CX_LIMITED_RANGE" pragma.  Nevertheless, the option applies to all
               languages.
    
           -fcx-fortran-rules
               Complex multiplication and division follow Fortran rules.  Range
               reduction is done as part of complex division, but there is no
               checking whether the result of a complex multiplication or division
               is "NaN + I*NaN", with an attempt to rescue the situation in that
               case.
    
               The default is -fno-cx-fortran-rules.
    
           The following options control optimizations that may improve
           performance, but are not enabled by any -O options.  This section
           includes experimental options that may produce broken code.
    
           -fbranch-probabilities
               After running a program compiled with -fprofile-arcs, you can
    
           -fprofile-values
               If combined with -fprofile-arcs, it adds code so that some data
               about values of expressions in the program is gathered.
    
               With -fbranch-probabilities, it reads back the data gathered from
               profiling values of expressions and adds REG_VALUE_PROFILE notes to
               instructions for their later usage in optimizations.
    
               Enabled with -fprofile-generate and -fprofile-use.
    
           -fvpt
               If combined with -fprofile-arcs, it instructs the compiler to add a
               code to gather information about values of expressions.
    
               With -fbranch-probabilities, it reads back the data gathered and
               actually performs the optimizations based on them.  Currently the
               optimizations include specialization of division operation using
               the knowledge about the value of the denominator.
    
           -frename-registers
               Attempt to avoid false dependencies in scheduled code by making use
               of registers left over after register allocation.  This
               optimization will most benefit processors with lots of registers.
               Depending on the debug information format adopted by the target,
               however, it can make debugging impossible, since variables will no
               longer stay in a "home register".
    
               Enabled by default with -funroll-loops.
    
           -ftracer
               Perform tail duplication to enlarge superblock size.  This
               transformation simplifies the control flow of the function allowing
               other optimizations to do better job.
    
               Enabled with -fprofile-use.
    
           -funroll-loops
               Unroll loops whose number of iterations can be determined at
               compile time or upon entry to the loop.  -funroll-loops implies
               -frerun-cse-after-loop, -fweb and -frename-registers.  It also
               turns on complete loop peeling (i.e. complete removal of loops with
               small constant number of iterations).  This option makes code
               larger, and may or may not make it run faster.
    
               Enabled with -fprofile-use.
    
           -funroll-all-loops
               Unroll all loops, even if their number of iterations is uncertain
               when the loop is entered.  This usually makes programs run more
               slowly.  -funroll-all-loops implies the same options as
               -funroll-loops.
               Move branches with loop invariant conditions out of the loop, with
               duplicates of the loop on both branches (modified according to
               result of the condition).
    
           -ffunction-sections
           -fdata-sections
               Place each function or data item into its own section in the output
               file if the target supports arbitrary sections.  The name of the
               function or the name of the data item determines the section's name
               in the output file.
    
               Use these options on systems where the linker can perform
               optimizations to improve locality of reference in the instruction
               space.  Most systems using the ELF object format and SPARC
               processors running Solaris 2 have linkers with such optimizations.
               AIX may have these optimizations in the future.
    
               Only use these options when there are significant benefits from
               doing so.  When you specify these options, the assembler and linker
               will create larger object and executable files and will also be
               slower.  You will not be able to use "gprof" on all systems if you
               specify this option and you may have problems with debugging if you
               specify both this option and -g.
    
           -fbranch-target-load-optimize
               Perform branch target register load optimization before prologue /
               epilogue threading.  The use of target registers can typically be
               exposed only during reload, thus hoisting loads out of loops and
               doing inter-block scheduling needs a separate optimization pass.
    
           -fbranch-target-load-optimize2
               Perform branch target register load optimization after prologue /
               epilogue threading.
    
           -fbtr-bb-exclusive
               When performing branch target register load optimization, don't
               reuse branch target registers in within any basic block.
    
           -fstack-protector
               Emit extra code to check for buffer overflows, such as stack
               smashing attacks.  This is done by adding a guard variable to
               functions with vulnerable objects.  This includes functions that
               call alloca, and functions with buffers larger than 8 bytes.  The
               guards are initialized when a function is entered and then checked
               when the function exits.  If a guard check fails, an error message
               is printed and the program exits.
    
           -fstack-protector-all
               Like -fstack-protector except that all functions are protected.
    
           -fsection-anchors
               Try to reduce the number of symbolic address calculations by using
                       int foo (void)
                       {
                         register int *xr = &x;
                         return xr[&a - &x] + xr[&b - &x] + xr[&c - &x];
                       }
    
               Not all targets support this option.
    
           --param name=value
               In some places, GCC uses various constants to control the amount of
               optimization that is done.  For example, GCC will not inline
               functions that contain more that a certain number of instructions.
               You can control some of these constants on the command-line using
               the --param option.
    
               The names of specific parameters, and the meaning of the values,
               are tied to the internals of the compiler, and are subject to
               change without notice in future releases.
    
               In each case, the value is an integer.  The allowable choices for
               name are given in the following table:
    
               sra-max-structure-size
                   The maximum structure size, in bytes, at which the scalar
                   replacement of aggregates (SRA) optimization will perform block
                   copies.  The default value, 0, implies that GCC will select the
                   most appropriate size itself.
    
               sra-field-structure-ratio
                   The threshold ratio (as a percentage) between instantiated
                   fields and the complete structure size.  We say that if the
                   ratio of the number of bytes in instantiated fields to the
                   number of bytes in the complete structure exceeds this
                   parameter, then block copies are not used.  The default is 75.
    
               struct-reorg-cold-struct-ratio
                   The threshold ratio (as a percentage) between a structure
                   frequency and the frequency of the hottest structure in the
                   program.  This parameter is used by struct-reorg optimization
                   enabled by -fipa-struct-reorg.  We say that if the ratio of a
                   structure frequency, calculated by profiling, to the hottest
                   structure frequency in the program is less than this parameter,
                   then structure reorganization is not applied to this structure.
                   The default is 10.
    
               predictable-branch-cost-outcome
                   When branch is predicted to be taken with probability lower
                   than this threshold (in percent), then it is considered well
                   predictable. The default is 10.
    
               max-crossjump-edges
                   The maximum number of incoming edges to consider for
                   The maximum code size expansion factor when copying basic
                   blocks instead of jumping.  The expansion is relative to a jump
                   instruction.  The default value is 8.
    
               max-goto-duplication-insns
                   The maximum number of instructions to duplicate to a block that
                   jumps to a computed goto.  To avoid O(N^2) behavior in a number
                   of passes, GCC factors computed gotos early in the compilation
                   process, and unfactors them as late as possible.  Only computed
                   jumps at the end of a basic blocks with no more than max-goto-
                   duplication-insns are unfactored.  The default value is 8.
    
               max-delay-slot-insn-search
                   The maximum number of instructions to consider when looking for
                   an instruction to fill a delay slot.  If more than this
                   arbitrary number of instructions is searched, the time savings
                   from filling the delay slot will be minimal so stop searching.
                   Increasing values mean more aggressive optimization, making the
                   compile time increase with probably small improvement in
                   executable run time.
    
               max-delay-slot-live-search
                   When trying to fill delay slots, the maximum number of
                   instructions to consider when searching for a block with valid
                   live register information.  Increasing this arbitrarily chosen
                   value means more aggressive optimization, increasing the
                   compile time.  This parameter should be removed when the delay
                   slot code is rewritten to maintain the control-flow graph.
    
               max-gcse-memory
                   The approximate maximum amount of memory that will be allocated
                   in order to perform the global common subexpression elimination
                   optimization.  If more memory than specified is required, the
                   optimization will not be done.
    
               max-gcse-passes
                   The maximum number of passes of GCSE to run.  The default is 1.
    
               max-pending-list-length
                   The maximum number of pending dependencies scheduling will
                   allow before flushing the current state and starting over.
                   Large functions with few branches or calls can create
                   excessively large lists which needlessly consume memory and
                   resources.
    
               max-inline-insns-single
                   Several parameters control the tree inliner used in gcc.  This
                   number sets the maximum number of instructions (counted in
                   GCC's internal representation) in a single function that the
                   tree inliner will consider for inlining.  This only affects
                   functions declared inline and methods implemented in a class
                   declaration (C++).  The default value is 450.
                   2700.
    
               large-function-growth
                   Specifies maximal growth of large function caused by inlining
                   in percents.  The default value is 100 which limits large
                   function growth to 2.0 times the original size.
    
               large-unit-insns
                   The limit specifying large translation unit.  Growth caused by
                   inlining of units larger than this limit is limited by --param
                   inline-unit-growth.  For small units this might be too tight
                   (consider unit consisting of function A that is inline and B
                   that just calls A three time.  If B is small relative to A, the
                   growth of unit is 300\% and yet such inlining is very sane.
                   For very large units consisting of small inlineable functions
                   however the overall unit growth limit is needed to avoid
                   exponential explosion of code size.  Thus for smaller units,
                   the size is increased to --param large-unit-insns before
                   applying --param inline-unit-growth.  The default is 10000
    
               inline-unit-growth
                   Specifies maximal overall growth of the compilation unit caused
                   by inlining.  The default value is 30 which limits unit growth
                   to 1.3 times the original size.
    
               ipcp-unit-growth
                   Specifies maximal overall growth of the compilation unit caused
                   by interprocedural constant propagation.  The default value is
                   10 which limits unit growth to 1.1 times the original size.
    
               large-stack-frame
                   The limit specifying large stack frames.  While inlining the
                   algorithm is trying to not grow past this limit too much.
                   Default value is 256 bytes.
    
               large-stack-frame-growth
                   Specifies maximal growth of large stack frames caused by
                   inlining in percents.  The default value is 1000 which limits
                   large stack frame growth to 11 times the original size.
    
               max-inline-insns-recursive
               max-inline-insns-recursive-auto
                   Specifies maximum number of instructions out-of-line copy of
                   self recursive inline function can grow into by performing
                   recursive inlining.
    
                   For functions declared inline --param max-inline-insns-
                   recursive is taken into account.  For function not declared
                   inline, recursive inlining happens only when -finline-functions
                   (included in -O3) is enabled and --param max-inline-insns-
                   recursive-auto is used.  The default value is 450.
    
                   recursion depth by increasing the prologue size or complexity
                   of function body to other optimizers.
    
                   When profile feedback is available (see -fprofile-generate) the
                   actual recursion depth can be guessed from probability that
                   function will recurse via given call expression.  This
                   parameter limits inlining only to call expression whose
                   probability exceeds given threshold (in percents).  The default
                   value is 10.
    
               inline-call-cost
                   Specify cost of call instruction relative to simple arithmetics
                   operations (having cost of 1).  Increasing this cost
                   disqualifies inlining of non-leaf functions and at the same
                   time increases size of leaf function that is believed to reduce
                   function size by being inlined.  In effect it increases amount
                   of inlining for code having large abstraction penalty (many
                   functions that just pass the arguments to other functions) and
                   decrease inlining for code with low abstraction penalty.  The
                   default value is 12.
    
               min-vect-loop-bound
                   The minimum number of iterations under which a loop will not
                   get vectorized when -ftree-vectorize is used.  The number of
                   iterations after vectorization needs to be greater than the
                   value specified by this option to allow vectorization.  The
                   default value is 0.
    
               max-unrolled-insns
                   The maximum number of instructions that a loop should have if
                   that loop is unrolled, and if the loop is unrolled, it
                   determines how many times the loop code is unrolled.
    
               max-average-unrolled-insns
                   The maximum number of instructions biased by probabilities of
                   their execution that a loop should have if that loop is
                   unrolled, and if the loop is unrolled, it determines how many
                   times the loop code is unrolled.
    
               max-unroll-times
                   The maximum number of unrollings of a single loop.
    
               max-peeled-insns
                   The maximum number of instructions that a loop should have if
                   that loop is peeled, and if the loop is peeled, it determines
                   how many times the loop code is peeled.
    
               max-peel-times
                   The maximum number of peelings of a single loop.
    
               max-completely-peeled-insns
                   The maximum number of insns of a completely peeled loop.
    
               lim-expensive
                   The minimum cost of an expensive expression in the loop
                   invariant motion.
    
               iv-consider-all-candidates-bound
                   Bound on number of candidates for induction variables below
                   that all candidates are considered for each use in induction
                   variable optimizations.  Only the most relevant candidates are
                   considered if there are more candidates, to avoid quadratic
                   time complexity.
    
               iv-max-considered-uses
                   The induction variable optimizations give up on loops that
                   contain more induction variable uses.
    
               iv-always-prune-cand-set-bound
                   If number of candidates in the set is smaller than this value,
                   we always try to remove unnecessary ivs from the set during its
                   optimization when a new iv is added to the set.
    
               scev-max-expr-size
                   Bound on size of expressions used in the scalar evolutions
                   analyzer.  Large expressions slow the analyzer.
    
               omega-max-vars
                   The maximum number of variables in an Omega constraint system.
                   The default value is 128.
    
               omega-max-geqs
                   The maximum number of inequalities in an Omega constraint
                   system.  The default value is 256.
    
               omega-max-eqs
                   The maximum number of equalities in an Omega constraint system.
                   The default value is 128.
    
               omega-max-wild-cards
                   The maximum number of wildcard variables that the Omega solver
                   will be able to insert.  The default value is 18.
    
               omega-hash-table-size
                   The size of the hash table in the Omega solver.  The default
                   value is 550.
    
               omega-max-keys
                   The maximal number of keys used by the Omega solver.  The
                   default value is 500.
    
               omega-eliminate-redundant-constraints
                   When set to 1, use expensive methods to eliminate all redundant
                   constraints.  The default value is 0.
    
    
               hot-bb-count-fraction
                   Select fraction of the maximal count of repetitions of basic
                   block in program given basic block needs to have to be
                   considered hot.
    
               hot-bb-frequency-fraction
                   Select fraction of the maximal frequency of executions of basic
                   block in function given basic block needs to have to be
                   considered hot
    
               max-predicted-iterations
                   The maximum number of loop iterations we predict statically.
                   This is useful in cases where function contain single loop with
                   known bound and other loop with unknown.  We predict the known
                   number of iterations correctly, while the unknown number of
                   iterations average to roughly 10.  This means that the loop
                   without bounds would appear artificially cold relative to the
                   other one.
    
               align-threshold
                   Select fraction of the maximal frequency of executions of basic
                   block in function given basic block will get aligned.
    
               align-loop-iterations
                   A loop expected to iterate at lest the selected number of
                   iterations will get aligned.
    
               tracer-dynamic-coverage
               tracer-dynamic-coverage-feedback
                   This value is used to limit superblock formation once the given
                   percentage of executed instructions is covered.  This limits
                   unnecessary code size expansion.
    
                   The tracer-dynamic-coverage-feedback is used only when profile
                   feedback is available.  The real profiles (as opposed to
                   statically estimated ones) are much less balanced allowing the
                   threshold to be larger value.
    
               tracer-max-code-growth
                   Stop tail duplication once code growth has reached given
                   percentage.  This is rather hokey argument, as most of the
                   duplicates will be eliminated later in cross jumping, so it may
                   be set to much higher values than is the desired code growth.
    
               tracer-min-branch-ratio
                   Stop reverse growth when the reverse probability of best edge
                   is less than this threshold (in percent).
    
               tracer-min-branch-ratio
               tracer-min-branch-ratio-feedback
                   Stop forward growth if the best edge do have probability lower
                   default is 1000.
    
               max-aliased-vops
                   Maximum number of virtual operands per function allowed to
                   represent aliases before triggering the alias partitioning
                   heuristic.  Alias partitioning reduces compile times and memory
                   consumption needed for aliasing at the expense of precision
                   loss in alias information.  The default value for this
                   parameter is 100 for -O1, 500 for -O2 and 1000 for -O3.
    
                   Notice that if a function contains more memory statements than
                   the value of this parameter, it is not really possible to
                   achieve this reduction.  In this case, the compiler will use
                   the number of memory statements as the value for max-aliased-
                   vops.
    
               avg-aliased-vops
                   Average number of virtual operands per statement allowed to
                   represent aliases before triggering the alias partitioning
                   heuristic.  This works in conjunction with max-aliased-vops.
                   If a function contains more than max-aliased-vops virtual
                   operators, then memory symbols will be grouped into memory
                   partitions until either the total number of virtual operators
                   is below max-aliased-vops or the average number of virtual
                   operators per memory statement is below avg-aliased-vops.  The
                   default value for this parameter is 1 for -O1 and -O2, and 3
                   for -O3.
    
               ggc-min-expand
                   GCC uses a garbage collector to manage its own memory
                   allocation.  This parameter specifies the minimum percentage by
                   which the garbage collector's heap should be allowed to expand
                   between collections.  Tuning this may improve compilation
                   speed; it has no effect on code generation.
    
                   The default is 30% + 70% * (RAM/1GB) with an upper bound of
                   100% when RAM >= 1GB.  If "getrlimit" is available, the notion
                   of "RAM" is the smallest of actual RAM and "RLIMIT_DATA" or
                   "RLIMIT_AS".  If GCC is not able to calculate RAM on a
                   particular platform, the lower bound of 30% is used.  Setting
                   this parameter and ggc-min-heapsize to zero causes a full
                   collection to occur at every opportunity.  This is extremely
                   slow, but can be useful for debugging.
    
               ggc-min-heapsize
                   Minimum size of the garbage collector's heap before it begins
                   bothering to collect garbage.  The first collection occurs
                   after the heap expands by ggc-min-expand% beyond ggc-min-
                   heapsize.  Again, tuning this may improve compilation speed,
                   and has no effect on code generation.
    
                   The default is the smaller of RAM/8, RLIMIT_RSS, or a limit
    
               max-cselib-memory-locations
                   The maximum number of memory locations cselib should take into
                   account.  Increasing values mean more aggressive optimization,
                   making the compile time increase with probably slightly better
                   performance.  The default value is 500.
    
               reorder-blocks-duplicate
               reorder-blocks-duplicate-feedback
                   Used by basic block reordering pass to decide whether to use
                   unconditional branch or duplicate the code on its destination.
                   Code is duplicated when its estimated size is smaller than this
                   value multiplied by the estimated size of unconditional jump in
                   the hot spots of the program.
    
                   The reorder-block-duplicate-feedback is used only when profile
                   feedback is available and may be set to higher values than
                   reorder-block-duplicate since information about the hot spots
                   is more accurate.
    
               max-sched-ready-insns
                   The maximum number of instructions ready to be issued the
                   scheduler should consider at any given time during the first
                   scheduling pass.  Increasing values mean more thorough
                   searches, making the compilation time increase with probably
                   little benefit.  The default value is 100.
    
               max-sched-region-blocks
                   The maximum number of blocks in a region to be considered for
                   interblock scheduling.  The default value is 10.
    
               max-pipeline-region-blocks
                   The maximum number of blocks in a region to be considered for
                   pipelining in the selective scheduler.  The default value is
                   15.
    
               max-sched-region-insns
                   The maximum number of insns in a region to be considered for
                   interblock scheduling.  The default value is 100.
    
               max-pipeline-region-insns
                   The maximum number of insns in a region to be considered for
                   pipelining in the selective scheduler.  The default value is
                   200.
    
               min-spec-prob
                   The minimum probability (in percents) of reaching a source
                   block for interblock speculative scheduling.  The default value
                   is 40.
    
               max-sched-extend-regions-iters
                   The maximum number of iterations through CFG to extend regions.
                   targeting same memory locations.  The default value is 1.
    
               selsched-max-lookahead
                   The maximum size of the lookahead window of selective
                   scheduling.  It is a depth of search for available
                   instructions.  The default value is 50.
    
               selsched-max-sched-times
                   The maximum number of times that an instruction will be
                   scheduled during selective scheduling.  This is the limit on
                   the number of iterations through which the instruction may be
                   pipelined.  The default value is 2.
    
               selsched-max-insns-to-rename
                   The maximum number of best instructions in the ready list that
                   are considered for renaming in the selective scheduler.  The
                   default value is 2.
    
               max-last-value-rtl
                   The maximum size measured as number of RTLs that can be
                   recorded in an expression in combiner for a pseudo register as
                   last known value of that register.  The default is 10000.
    
               integer-share-limit
                   Small integer constants can use a shared data structure,
                   reducing the compiler's memory usage and increasing its speed.
                   This sets the maximum value of a shared integer constant.  The
                   default value is 256.
    
               min-virtual-mappings
                   Specifies the minimum number of virtual mappings in the
                   incremental SSA updater that should be registered to trigger
                   the virtual mappings heuristic defined by virtual-mappings-
                   ratio.  The default value is 100.
    
               virtual-mappings-ratio
                   If the number of virtual mappings is virtual-mappings-ratio
                   bigger than the number of virtual symbols to be updated, then
                   the incremental SSA updater switches to a full update for those
                   symbols.  The default ratio is 3.
    
               ssp-buffer-size
                   The minimum size of buffers (i.e. arrays) that will receive
                   stack smashing protection when -fstack-protection is used.
    
               max-jump-thread-duplication-stmts
                   Maximum number of statements allowed in a block that needs to
                   be duplicated when threading jumps.
    
               max-fields-for-field-sensitive
                   Maximum number of fields in a structure we will treat in a
                   field sensitive manner during pointer analysis.  The default is
    
               l1-cache-size
                   The size of L1 cache, in kilobytes.
    
               l2-cache-size
                   The size of L2 cache, in kilobytes.
    
               use-canonical-types
                   Whether the compiler should use the "canonical" type system.
                   By default, this should always be 1, which uses a more
                   efficient internal mechanism for comparing types in C++ and
                   Objective-C++.  However, if bugs in the canonical type system
                   are causing compilation failures, set this value to 0 to
                   disable canonical types.
    
               switch-conversion-max-branch-ratio
                   Switch initialization conversion will refuse to create arrays
                   that are bigger than switch-conversion-max-branch-ratio times
                   the number of branches in the switch.
    
               max-partial-antic-length
                   Maximum length of the partial antic set computed during the
                   tree partial redundancy elimination optimization (-ftree-pre)
                   when optimizing at -O3 and above.  For some sorts of source
                   code the enhanced partial redundancy elimination optimization
                   can run away, consuming all of the memory available on the host
                   machine.  This parameter sets a limit on the length of the sets
                   that are computed, which prevents the runaway behavior.
                   Setting a value of 0 for this parameter will allow an unlimited
                   set length.
    
               sccvn-max-scc-size
                   Maximum size of a strongly connected component (SCC) during
                   SCCVN processing.  If this limit is hit, SCCVN processing for
                   the whole function will not be done and optimizations depending
                   on it will be disabled.  The default maximum SCC size is 10000.
    
               ira-max-loops-num
                   IRA uses a regional register allocation by default.  If a
                   function contains loops more than number given by the
                   parameter, only at most given number of the most frequently
                   executed loops will form regions for the regional register
                   allocation.  The default value of the parameter is 100.
    
               ira-max-conflict-table-size
                   Although IRA uses a sophisticated algorithm of compression
                   conflict table, the table can be still big for huge functions.
                   If the conflict table for a function could be more than size in
                   MB given by the parameter, the conflict table is not built and
                   faster, simpler, and lower quality register allocation
                   algorithm will be used.  The algorithm do not use pseudo-
                   register conflicts.  The default value of the parameter is
                   enabled, analysis for that function is retried without it,
                   after removing all debug insns from the function.  If the limit
                   is exceeded even without debug insns, var tracking analysis is
                   completely disabled for the function.  Setting the parameter to
                   zero makes it unlimited.
    
               min-nondebug-insn-uid
                   Use uids starting at this parameter for nondebug insns.  The
                   range below the parameter is reserved exclusively for debug
                   insns created by -fvar-tracking-assignments, but debug insns
                   may get (non-overlapping) uids above it if the reserved range
                   is exhausted.
    
       Options Controlling the Preprocessor
           These options control the C preprocessor, which is run on each C source
           file before actual compilation.
    
           If you use the -E option, nothing is done except preprocessing.  Some
           of these options make sense only together with -E because they cause
           the preprocessor output to be unsuitable for actual compilation.
    
           -Wp,option
               You can use -Wp,option to bypass the compiler driver and pass
               option directly through to the preprocessor.  If option contains
               commas, it is split into multiple options at the commas.  However,
               many options are modified, translated or interpreted by the
               compiler driver before being passed to the preprocessor, and -Wp
               forcibly bypasses this phase.  The preprocessor's direct interface
               is undocumented and subject to change, so whenever possible you
               should avoid using -Wp and let the driver handle the options
               instead.
    
           -Xpreprocessor option
               Pass option as an option to the preprocessor.  You can use this to
               supply system-specific preprocessor options which GCC does not know
               how to recognize.
    
               If you want to pass an option that takes an argument, you must use
               -Xpreprocessor twice, once for the option and once for the
               argument.
    
           -D name
               Predefine name as a macro, with definition 1.
    
           -D name=definition
               The contents of definition are tokenized and processed as if they
               appeared during translation phase three in a #define directive.  In
               particular, the definition will be truncated by embedded newline
               characters.
    
               If you are invoking the preprocessor from a shell or shell-like
               program you may need to use the shell's quoting syntax to protect
               with a -D option.
    
           -undef
               Do not predefine any system-specific or GCC-specific macros.  The
               standard predefined macros remain defined.
    
           -I dir
               Add the directory dir to the list of directories to be searched for
               header files.  Directories named by -I are searched before the
               standard system include directories.  If the directory dir is a
               standard system include directory, the option is ignored to ensure
               that the default search order for system directories and the
               special treatment of system headers are not defeated .  If dir
               begins with "=", then the "=" will be replaced by the sysroot
               prefix; see --sysroot and -isysroot.
    
           -o file
               Write output to file.  This is the same as specifying file as the
               second non-option argument to cpp.  gcc has a different
               interpretation of a second non-option argument, so you must use -o
               to specify the output file.
    
           -Wall
               Turns on all optional warnings which are desirable for normal code.
               At present this is -Wcomment, -Wtrigraphs, -Wmultichar and a
               warning about integer promotion causing a change of sign in "#if"
               expressions.  Note that many of the preprocessor's warnings are on
               by default and have no options to control them.
    
           -Wcomment
           -Wcomments
               Warn whenever a comment-start sequence /* appears in a /* comment,
               or whenever a backslash-newline appears in a // comment.  (Both
               forms have the same effect.)
    
           -Wtrigraphs
               Most trigraphs in comments cannot affect the meaning of the
               program.  However, a trigraph that would form an escaped newline
               (??/ at the end of a line) can, by changing where the comment
               begins or ends.  Therefore, only trigraphs that would form escaped
               newlines produce warnings inside a comment.
    
               This option is implied by -Wall.  If -Wall is not given, this
               option is still enabled unless trigraphs are enabled.  To get
               trigraph conversion without warnings, but get the other -Wall
               warnings, use -trigraphs -Wall -Wno-trigraphs.
    
           -Wtraditional
               Warn about certain constructs that behave differently in
               traditional and ISO C.  Also warn about ISO C constructs that have
               no traditional C equivalent, and problematic constructs which
               should be avoided.
    
               Note: If a macro is actually used, but only used in skipped
               conditional blocks, then CPP will report it as unused.  To avoid
               the warning in such a case, you might improve the scope of the
               macro's definition by, for example, moving it into the first
               skipped block.  Alternatively, you could provide a dummy use with
               something like:
    
                       #if defined the_macro_causing_the_warning
                       #endif
    
           -Wendif-labels
               Warn whenever an #else or an #endif are followed by text.  This
               usually happens in code of the form
    
                       #if FOO
                       ...
                       #else FOO
                       ...
                       #endif FOO
    
               The second and third "FOO" should be in comments, but often are not
               in older programs.  This warning is on by default.
    
           -Werror
               Make all warnings into hard errors.  Source code which triggers
               warnings will be rejected.
    
           -Wsystem-headers
               Issue warnings for code in system headers.  These are normally
               unhelpful in finding bugs in your own code, therefore suppressed.
               If you are responsible for the system library, you may want to see
               them.
    
           -w  Suppress all warnings, including those which GNU CPP issues by
               default.
    
           -pedantic
               Issue all the mandatory diagnostics listed in the C standard.  Some
               of them are left out by default, since they trigger frequently on
               harmless code.
    
           -pedantic-errors
               Issue all the mandatory diagnostics, and make all mandatory
               diagnostics into errors.  This includes mandatory diagnostics that
               GCC issues without -pedantic but treats as warnings.
    
           -M  Instead of outputting the result of preprocessing, output a rule
               suitable for make describing the dependencies of the main source
               file.  The preprocessor outputs one make rule containing the object
               file name for that source file, a colon, and the names of all the
               included files, including those coming from -include or -imacros
    
               Passing -M to the driver implies -E, and suppresses warnings with
               an implicit -w.
    
           -MM Like -M but do not mention header files that are found in system
               header directories, nor header files that are included, directly or
               indirectly, from such a header.
    
               This implies that the choice of angle brackets or double quotes in
               an #include directive does not in itself determine whether that
               header will appear in -MM dependency output.  This is a slight
               change in semantics from GCC versions 3.0 and earlier.
    
           -MF file
               When used with -M or -MM, specifies a file to write the
               dependencies to.  If no -MF switch is given the preprocessor sends
               the rules to the same place it would have sent preprocessed output.
    
               When used with the driver options -MD or -MMD, -MF overrides the
               default dependency output file.
    
           -MG In conjunction with an option such as -M requesting dependency
               generation, -MG assumes missing header files are generated files
               and adds them to the dependency list without raising an error.  The
               dependency filename is taken directly from the "#include" directive
               without prepending any path.  -MG also suppresses preprocessed
               output, as a missing header file renders this useless.
    
               This feature is used in automatic updating of makefiles.
    
           -MP This option instructs CPP to add a phony target for each dependency
               other than the main file, causing each to depend on nothing.  These
               dummy rules work around errors make gives if you remove header
               files without updating the Makefile to match.
    
               This is typical output:
    
                       test.o: test.c test.h
    
                       test.h:
    
           -MT target
               Change the target of the rule emitted by dependency generation.  By
               default CPP takes the name of the main input file, deletes any
               directory components and any file suffix such as .c, and appends
               the platform's usual object suffix.  The result is the target.
    
               An -MT option will set the target to be exactly the string you
               specify.  If you want multiple targets, you can specify them as a
               single argument to -MT, or use multiple -MT options.
    
               For example, -MT '$(objpfx)foo.o' might give
               If it is, the driver uses its argument but with a suffix of .d,
               otherwise it takes the name of the input file, removes any
               directory components and suffix, and applies a .d suffix.
    
               If -MD is used in conjunction with -E, any -o switch is understood
               to specify the dependency output file, but if used without -E, each
               -o is understood to specify a target object file.
    
               Since -E is not implied, -MD can be used to generate a dependency
               output file as a side-effect of the compilation process.
    
           -MMD
               Like -MD except mention only user header files, not system header
               files.
    
           -fpch-deps
               When using precompiled headers, this flag will cause the
               dependency-output flags to also list the files from the precompiled
               header's dependencies.  If not specified only the precompiled
               header would be listed and not the files that were used to create
               it because those files are not consulted when a precompiled header
               is used.
    
           -fpch-preprocess
               This option allows use of a precompiled header together with -E.
               It inserts a special "#pragma", "#pragma GCC pch_preprocess
               "<filename>"" in the output to mark the place where the precompiled
               header was found, and its filename.  When -fpreprocessed is in use,
               GCC recognizes this "#pragma" and loads the PCH.
    
               This option is off by default, because the resulting preprocessed
               output is only really suitable as input to GCC.  It is switched on
               by -save-temps.
    
               You should not write this "#pragma" in your own code, but it is
               safe to edit the filename if the PCH file is available in a
               different location.  The filename may be absolute or it may be
               relative to GCC's current directory.
    
           -x c
           -x c++
           -x objective-c
           -x assembler-with-cpp
               Specify the source language: C, C++, Objective-C, or assembly.
               This has nothing to do with standards conformance or extensions; it
               merely selects which base syntax to expect.  If you give none of
               these options, cpp will deduce the language from the extension of
               the source file: .c, .cc, .m, or .S.  Some other common extensions
               for C++ and assembly are also recognized.  If cpp does not
               recognize the extension, it will treat the file as C; this is the
               most generic mode.
    
               "c89"
                   The ISO C standard from 1990.  c89 is the customary shorthand
                   for this version of the standard.
    
                   The -ansi option is equivalent to -std=c89.
    
               "iso9899:199409"
                   The 1990 C standard, as amended in 1994.
    
               "iso9899:1999"
               "c99"
               "iso9899:199x"
               "c9x"
                   The revised ISO C standard, published in December 1999.  Before
                   publication, this was known as C9X.
    
               "gnu89"
                   The 1990 C standard plus GNU extensions.  This is the default.
    
               "gnu99"
               "gnu9x"
                   The 1999 C standard plus GNU extensions.
    
               "c++98"
                   The 1998 ISO C++ standard plus amendments.
    
               "gnu++98"
                   The same as -std=c++98 plus GNU extensions.  This is the
                   default for C++ code.
    
           -I- Split the include path.  Any directories specified with -I options
               before -I- are searched only for headers requested with
               "#include "file""; they are not searched for "#include <file>".  If
               additional directories are specified with -I options after the -I-,
               those directories are searched for all #include directives.
    
               In addition, -I- inhibits the use of the directory of the current
               file directory as the first search directory for "#include "file"".
               This option has been deprecated.
    
           -nostdinc
               Do not search the standard system directories for header files.
               Only the directories you have specified with -I options (and the
               directory of the current file, if appropriate) are searched.
    
           -nostdinc++
               Do not search for header files in the C++-specific standard
               directories, but do still search the other standard directories.
               (This option is used when building the C++ library.)
    
           -include file
               Process file as if "#include "file"" appeared as the first line of
    
               All files specified by -imacros are processed before all files
               specified by -include.
    
           -idirafter dir
               Search dir for header files, but do it after all directories
               specified with -I and the standard system directories have been
               exhausted.  dir is treated as a system include directory.  If dir
               begins with "=", then the "=" will be replaced by the sysroot
               prefix; see --sysroot and -isysroot.
    
           -iprefix prefix
               Specify prefix as the prefix for subsequent -iwithprefix options.
               If the prefix represents a directory, you should include the final
               /.
    
           -iwithprefix dir
           -iwithprefixbefore dir
               Append dir to the prefix specified previously with -iprefix, and
               add the resulting directory to the include search path.
               -iwithprefixbefore puts it in the same place -I would; -iwithprefix
               puts it where -idirafter would.
    
           -isysroot dir
               This option is like the --sysroot option, but applies only to
               header files.  See the --sysroot option for more information.
    
           -imultilib dir
               Use dir as a subdirectory of the directory containing target-
               specific C++ headers.
    
           -isystem dir
               Search dir for header files, after all directories specified by -I
               but before the standard system directories.  Mark it as a system
               directory, so that it gets the same special treatment as is applied
               to the standard system directories.  If dir begins with "=", then
               the "=" will be replaced by the sysroot prefix; see --sysroot and
               -isysroot.
    
           -iquote dir
               Search dir only for header files requested with "#include "file"";
               they are not searched for "#include <file>", before all directories
               specified by -I and before the standard system directories.  If dir
               begins with "=", then the "=" will be replaced by the sysroot
               prefix; see --sysroot and -isysroot.
    
           -fdirectives-only
               When preprocessing, handle directives, but do not expand macros.
    
               The option's behavior depends on the -E and -fpreprocessed options.
    
               With -E, preprocessing is limited to the handling of directives
    
           -fdollars-in-identifiers
               Accept $ in identifiers.
    
           -fextended-identifiers
               Accept universal character names in identifiers.  This option is
               experimental; in a future version of GCC, it will be enabled by
               default for C99 and C++.
    
           -fpreprocessed
               Indicate to the preprocessor that the input file has already been
               preprocessed.  This suppresses things like macro expansion,
               trigraph conversion, escaped newline splicing, and processing of
               most directives.  The preprocessor still recognizes and removes
               comments, so that you can pass a file preprocessed with -C to the
               compiler without problems.  In this mode the integrated
               preprocessor is little more than a tokenizer for the front ends.
    
               -fpreprocessed is implicit if the input file has one of the
               extensions .i, .ii or .mi.  These are the extensions that GCC uses
               for preprocessed files created by -save-temps.
    
           -ftabstop=width
               Set the distance between tab stops.  This helps the preprocessor
               report correct column numbers in warnings or errors, even if tabs
               appear on the line.  If the value is less than 1 or greater than
               100, the option is ignored.  The default is 8.
    
           -fexec-charset=charset
               Set the execution character set, used for string and character
               constants.  The default is UTF-8.  charset can be any encoding
               supported by the system's "iconv" library routine.
    
           -fwide-exec-charset=charset
               Set the wide execution character set, used for wide string and
               character constants.  The default is UTF-32 or UTF-16, whichever
               corresponds to the width of "wchar_t".  As with -fexec-charset,
               charset can be any encoding supported by the system's "iconv"
               library routine; however, you will have problems with encodings
               that do not fit exactly in "wchar_t".
    
           -finput-charset=charset
               Set the input character set, used for translation from the
               character set of the input file to the source character set used by
               GCC.  If the locale does not specify, or GCC cannot get this
               information from the locale, the default is UTF-8.  This can be
               overridden by either the locale or this command line option.
               Currently the command line option takes precedence if there's a
               conflict.  charset can be any encoding supported by the system's
               "iconv" library routine.
    
           -fworking-directory
               Enable generation of linemarkers in the preprocessor output that
               if diagnostics are being scanned by a program that does not
               understand the column numbers, such as dejagnu.
    
           -A predicate=answer
               Make an assertion with the predicate predicate and answer answer.
               This form is preferred to the older form -A predicate(answer),
               which is still supported, because it does not use shell special
               characters.
    
           -A -predicate=answer
               Cancel an assertion with the predicate predicate and answer answer.
    
           -dCHARS
               CHARS is a sequence of one or more of the following characters, and
               must not be preceded by a space.  Other characters are interpreted
               by the compiler proper, or reserved for future versions of GCC, and
               so are silently ignored.  If you specify characters whose behavior
               conflicts, the result is undefined.
    
               M   Instead of the normal output, generate a list of #define
                   directives for all the macros defined during the execution of
                   the preprocessor, including predefined macros.  This gives you
                   a way of finding out what is predefined in your version of the
                   preprocessor.  Assuming you have no file foo.h, the command
    
                           touch foo.h; cpp -dM foo.h
    
                   will show all the predefined macros.
    
                   If you use -dM without the -E option, -dM is interpreted as a
                   synonym for -fdump-rtl-mach.
    
               D   Like M except in two respects: it does not include the
                   predefined macros, and it outputs both the #define directives
                   and the result of preprocessing.  Both kinds of output go to
                   the standard output file.
    
               N   Like D, but emit only the macro names, not their expansions.
    
               I   Output #include directives in addition to the result of
                   preprocessing.
    
               U   Like D except that only macros that are expanded, or whose
                   definedness is tested in preprocessor directives, are output;
                   the output is delayed until the use or test of the macro; and
                   #undef directives are also output for macros tested but
                   undefined at the time.
    
           -P  Inhibit generation of linemarkers in the output from the
               preprocessor.  This might be useful when running the preprocessor
               on something that is not C code, and will be sent to a program
               which might be confused by the linemarkers.
               passed through to the output file where the macro is expanded.
    
               In addition to the side-effects of the -C option, the -CC option
               causes all C++-style comments inside a macro to be converted to
               C-style comments.  This is to prevent later use of that macro from
               inadvertently commenting out the remainder of the source line.
    
               The -CC option is generally used to support lint comments.
    
           -traditional-cpp
               Try to imitate the behavior of old-fashioned C preprocessors, as
               opposed to ISO C preprocessors.
    
           -trigraphs
               Process trigraph sequences.  These are three-character sequences,
               all starting with ??, that are defined by ISO C to stand for single
               characters.  For example, ??/ stands for \, so '??/n' is a
               character constant for a newline.  By default, GCC ignores
               trigraphs, but in standard-conforming modes it converts them.  See
               the -std and -ansi options.
    
               The nine trigraphs and their replacements are
    
                       Trigraph:       ??(  ??)  ??<  ??>  ??=  ??/  ??'  ??!  ??-
                       Replacement:      [    ]    {    }    #    \    ^    |    ~
    
           -remap
               Enable special code to work around file systems which only permit
               very short file names, such as MS-DOS.
    
           --help
           --target-help
               Print text describing all the command line options instead of
               preprocessing anything.
    
           -v  Verbose mode.  Print out GNU CPP's version number at the beginning
               of execution, and report the final form of the include path.
    
           -H  Print the name of each header file used, in addition to other
               normal activities.  Each name is indented to show how deep in the
               #include stack it is.  Precompiled header files are also printed,
               even if they are found to be invalid; an invalid precompiled header
               file is printed with ...x and a valid one with ...! .
    
           -version
           --version
               Print out GNU CPP's version number.  With one dash, proceed to
               preprocess as normal.  With two dashes, exit immediately.
    
       Passing Options to the Assembler
           You can pass options to the assembler.
    
           an executable output file.  They are meaningless if the compiler is not
           doing a link step.
    
           object-file-name
               A file name that does not end in a special recognized suffix is
               considered to name an object file or library.  (Object files are
               distinguished from libraries by the linker according to the file
               contents.)  If linking is done, these object files are used as
               input to the linker.
    
           -c
           -S
           -E  If any of these options is used, then the linker is not run, and
               object file names should not be used as arguments.
    
           -llibrary
           -l library
               Search the library named library when linking.  (The second
               alternative with the library as a separate argument is only for
               POSIX compliance and is not recommended.)
    
               It makes a difference where in the command you write this option;
               the linker searches and processes libraries and object files in the
               order they are specified.  Thus, foo.o -lz bar.o searches library z
               after file foo.o but before bar.o.  If bar.o refers to functions in
               z, those functions may not be loaded.
    
               The linker searches a standard list of directories for the library,
               which is actually a file named liblibrary.a.  The linker then uses
               this file as if it had been specified precisely by name.
    
               The directories searched include several standard system
               directories plus any that you specify with -L.
    
               Normally the files found this way are library files---archive files
               whose members are object files.  The linker handles an archive file
               by scanning through it for members which define symbols that have
               so far been referenced but not defined.  But if the file that is
               found is an ordinary object file, it is linked in the usual
               fashion.  The only difference between using an -l option and
               specifying a file name is that -l surrounds library with lib and .a
               and searches several directories.
    
           -lobjc
               You need this special case of the -l option in order to link an
               Objective-C or Objective-C++ program.
    
           -nostartfiles
               Do not use the standard system startup files when linking.  The
               standard system libraries are used normally, unless -nostdlib or
               -nodefaultlibs is used.
    
               usually resolved by entries in libc.  These entry points should be
               supplied through some other mechanism when this option is
               specified.
    
               One of the standard libraries bypassed by -nostdlib and
               -nodefaultlibs is libgcc.a, a library of internal subroutines that
               GCC uses to overcome shortcomings of particular machines, or
               special needs for some languages.
    
               In most cases, you need libgcc.a even when you want to avoid other
               standard libraries.  In other words, when you specify -nostdlib or
               -nodefaultlibs you should usually specify -lgcc as well.  This
               ensures that you have no unresolved references to internal GCC
               library subroutines.  (For example, __main, used to ensure C++
               constructors will be called.)
    
           -pie
               Produce a position independent executable on targets which support
               it.  For predictable results, you must also specify the same set of
               options that were used to generate code (-fpie, -fPIE, or model
               suboptions) when you specify this option.
    
           -rdynamic
               Pass the flag -export-dynamic to the ELF linker, on targets that
               support it. This instructs the linker to add all symbols, not only
               used ones, to the dynamic symbol table. This option is needed for
               some uses of "dlopen" or to allow obtaining backtraces from within
               a program.
    
           -s  Remove all symbol table and relocation information from the
               executable.
    
           -static
               On systems that support dynamic linking, this prevents linking with
               the shared libraries.  On other systems, this option has no effect.
    
           -shared
               Produce a shared object which can then be linked with other objects
               to form an executable.  Not all systems support this option.  For
               predictable results, you must also specify the same set of options
               that were used to generate code (-fpic, -fPIC, or model suboptions)
               when you specify this option.[1]
    
           -shared-libgcc
           -static-libgcc
               On systems that provide libgcc as a shared library, these options
               force the use of either the shared or static version respectively.
               If no shared version of libgcc was built when the compiler was
               configured, these options have no effect.
    
               There are several situations in which an application should use the
               shared libgcc instead of the static version.  The most common of
               --eh-frame-hdr, it will link the shared version of libgcc into
               shared libraries by default.  Otherwise, it will take advantage of
               the linker and optimize away the linking with the shared version of
               libgcc, linking with the static version of libgcc by default.  This
               allows exceptions to propagate through such shared libraries,
               without incurring relocation costs at library load time.
    
               However, if a library or main executable is supposed to throw or
               catch exceptions, you must link it using the G++ or GCJ driver, as
               appropriate for the languages used in the program, or using the
               option -shared-libgcc, such that it is linked with the shared
               libgcc.
    
           -symbolic
               Bind references to global symbols when building a shared object.
               Warn about any unresolved references (unless overridden by the link
               editor option -Xlinker -z -Xlinker defs).  Only a few systems
               support this option.
    
           -T script
               Use script as the linker script.  This option is supported by most
               systems using the GNU linker.  On some targets, such as bare-board
               targets without an operating system, the -T option may be required
               when linking to avoid references to undefined symbols.
    
           -Xlinker option
               Pass option as an option to the linker.  You can use this to supply
               system-specific linker options which GCC does not know how to
               recognize.
    
               If you want to pass an option that takes a separate argument, you
               must use -Xlinker twice, once for the option and once for the
               argument.  For example, to pass -assert definitions, you must write
               -Xlinker -assert -Xlinker definitions.  It does not work to write
               -Xlinker "-assert definitions", because this passes the entire
               string as a single argument, which is not what the linker expects.
    
               When using the GNU linker, it is usually more convenient to pass
               arguments to linker options using the option=value syntax than as
               separate arguments.  For example, you can specify -Xlinker
               -Map=output.map rather than -Xlinker -Map -Xlinker output.map.
               Other linkers may not support this syntax for command-line options.
    
           -Wl,option
               Pass option as an option to the linker.  If option contains commas,
               it is split into multiple options at the commas.  You can use this
               syntax to pass an argument to the option.  For example,
               -Wl,-Map,output.map passes -Map output.map to the linker.  When
               using the GNU linker, you can also get the same effect with
               -Wl,-Map=output.map.
    
           -u symbol
               vendor-supplied system header files (use -isystem for that).  If
               you use more than one -I option, the directories are scanned in
               left-to-right order; the standard system directories come after.
    
               If a standard system include directory, or a directory specified
               with -isystem, is also specified with -I, the -I option will be
               ignored.  The directory will still be searched but as a system
               directory at its normal position in the system include chain.  This
               is to ensure that GCC's procedure to fix buggy system headers and
               the ordering for the include_next directive are not inadvertently
               changed.  If you really need to change the search order for system
               directories, use the -nostdinc and/or -isystem options.
    
           -iquotedir
               Add the directory dir to the head of the list of directories to be
               searched for header files only for the case of #include "file";
               they are not searched for #include <file>, otherwise just like -I.
    
           -Ldir
               Add directory dir to the list of directories to be searched for -l.
    
           -Bprefix
               This option specifies where to find the executables, libraries,
               include files, and data files of the compiler itself.
    
               The compiler driver program runs one or more of the subprograms
               cpp, cc1, as and ld.  It tries prefix as a prefix for each program
               it tries to run, both with and without machine/version/.
    
               For each subprogram to be run, the compiler driver first tries the
               -B prefix, if any.  If that name is not found, or if -B was not
               specified, the driver tries two standard prefixes, which are
               /usr/lib/gcc/ and /usr/local/lib/gcc/.  If neither of those results
               in a file name that is found, the unmodified program name is
               searched for using the directories specified in your PATH
               environment variable.
    
               The compiler will check to see if the path provided by the -B
               refers to a directory, and if necessary it will add a directory
               separator character at the end of the path.
    
               -B prefixes that effectively specify directory names also apply to
               libraries in the linker, because the compiler translates these
               options into -L options for the linker.  They also apply to
               includes files in the preprocessor, because the compiler translates
               these options into -isystem options for the preprocessor.  In this
               case, the compiler appends include to the prefix.
    
               The run-time support file libgcc.a can also be searched for using
               the -B prefix, if needed.  If it is not found there, the two
               standard prefixes above are tried, and that is all.  The file is
               left out of the link if it is not found by those means.
               line, and they are processed in order, from left to right.
    
           --sysroot=dir
               Use dir as the logical root directory for headers and libraries.
               For example, if the compiler would normally search for headers in
               /usr/include and libraries in /usr/lib, it will instead search
               dir/usr/include and dir/usr/lib.
    
               If you use both this option and the -isysroot option, then the
               --sysroot option will apply to libraries, but the -isysroot option
               will apply to header files.
    
               The GNU linker (beginning with version 2.16) has the necessary
               support for this option.  If your linker does not support this
               option, the header file aspect of --sysroot will still work, but
               the library aspect will not.
    
           -I- This option has been deprecated.  Please use -iquote instead for -I
               directories before the -I- and remove the -I-.  Any directories you
               specify with -I options before the -I- option are searched only for
               the case of #include "file"; they are not searched for #include
               <file>.
    
               If additional directories are specified with -I options after the
               -I-, these directories are searched for all #include directives.
               (Ordinarily all -I directories are used this way.)
    
               In addition, the -I- option inhibits the use of the current
               directory (where the current input file came from) as the first
               search directory for #include "file".  There is no way to override
               this effect of -I-.  With -I. you can specify searching the
               directory which was current when the compiler was invoked.  That is
               not exactly the same as what the preprocessor does by default, but
               it is often satisfactory.
    
               -I- does not inhibit the use of the standard system directories for
               header files.  Thus, -I- and -nostdinc are independent.
    
       Specifying Target Machine and Compiler Version
           The usual way to run GCC is to run the executable called gcc, or
           <machine>-gcc when cross-compiling, or <machine>-gcc-<version> to run a
           version other than the one that was installed last.  Sometimes this is
           inconvenient, so GCC provides options that will switch to another
           cross-compiler or version.
    
           -b machine
               The argument machine specifies the target machine for compilation.
    
               The value to use for machine is the same as was specified as the
               machine type when configuring GCC as a cross-compiler.  For
               example, if a cross-compiler was configured with configure arm-elf,
               meaning to compile for an arm processor with elf binaries, then you
    
       Hardware Models and Configurations
           Earlier we discussed the standard option -b which chooses among
           different installed compilers for completely different target machines,
           such as VAX vs. 68000 vs. 80386.
    
           In addition, each of these target machine types can have its own
           special options, starting with -m, to choose among various hardware
           models or configurations---for example, 68010 vs 68020, floating
           coprocessor or none.  A single installed version of the compiler can
           compile for any model or configuration, according to the options
           specified.
    
           Some configurations of the compiler also support additional special
           options, usually for compatibility with other compilers on the same
           platform.
    
       ARC Options
           These options are defined for ARC implementations:
    
           -EL Compile code for little endian mode.  This is the default.
    
           -EB Compile code for big endian mode.
    
           -mmangle-cpu
               Prepend the name of the cpu to all public symbol names.  In
               multiple-processor systems, there are many ARC variants with
               different instruction and register set characteristics.  This flag
               prevents code compiled for one cpu to be linked with code compiled
               for another.  No facility exists for handling variants that are
               "almost identical".  This is an all or nothing option.
    
           -mcpu=cpu
               Compile code for ARC variant cpu.  Which variants are supported
               depend on the configuration.  All variants support -mcpu=base, this
               is the default.
    
           -mtext=text-section
           -mdata=data-section
           -mrodata=readonly-data-section
               Put functions, data, and readonly data in text-section, data-
               section, and readonly-data-section respectively by default.  This
               can be overridden with the "section" attribute.
    
           -mfix-cortex-m3-ldrd
               Some Cortex-M3 cores can cause data corruption when "ldrd"
               instructions with overlapping destination and base registers are
               used.  This option avoids generating these instructions.  This
               option is enabled by default when -mcpu=cortex-m3 is specified.
    
       ARM Options
           These -m options are defined for Advanced RISC Machines (ARM)
           architectures:
               This is a synonym for -mapcs-frame.
    
           -mthumb-interwork
               Generate code which supports calling between the ARM and Thumb
               instruction sets.  Without this option the two instruction sets
               cannot be reliably used inside one program.  The default is
               -mno-thumb-interwork, since slightly larger code is generated when
               -mthumb-interwork is specified.
    
           -mno-sched-prolog
               Prevent the reordering of instructions in the function prolog, or
               the merging of those instruction with the instructions in the
               function's body.  This means that all functions will start with a
               recognizable set of instructions (or in fact one of a choice from a
               small set of different function prologues), and this information
               can be used to locate the start if functions inside an executable
               piece of code.  The default is -msched-prolog.
    
           -mfloat-abi=name
               Specifies which floating-point ABI to use.  Permissible values are:
               soft, softfp and hard.
    
               Specifying soft causes GCC to generate output containing library
               calls for floating-point operations.  softfp allows the generation
               of code using hardware floating-point instructions, but still uses
               the soft-float calling conventions.  hard allows generation of
               floating-point instructions and uses FPU-specific calling
               conventions.
    
               Using -mfloat-abi=hard with VFP coprocessors is not supported.  Use
               -mfloat-abi=softfp with the appropriate -mfpu option to allow the
               compiler to generate code that makes use of the hardware floating-
               point capabilities for these CPUs.
    
               The default depends on the specific target configuration.  Note
               that the hard-float and soft-float ABIs are not link-compatible;
               you must compile your entire program with the same ABI, and link
               with a compatible set of libraries.
    
           -mhard-float
               Equivalent to -mfloat-abi=hard.
    
           -msoft-float
               Equivalent to -mfloat-abi=soft.
    
           -mlittle-endian
               Generate code for a processor running in little-endian mode.  This
               is the default for all standard configurations.
    
           -mbig-endian
               Generate code for a processor running in big-endian mode; the
               default is to compile code for a little-endian processor.
               arm7dm, arm7di, arm7dmi, arm70, arm700, arm700i, arm710, arm710c,
               arm7100, arm720, arm7500, arm7500fe, arm7tdmi, arm7tdmi-s, arm710t,
               arm720t, arm740t, strongarm, strongarm110, strongarm1100,
               strongarm1110, arm8, arm810, arm9, arm9e, arm920, arm920t, arm922t,
               arm946e-s, arm966e-s, arm968e-s, arm926ej-s, arm940t, arm9tdmi,
               arm10tdmi, arm1020t, arm1026ej-s, arm10e, arm1020e, arm1022e,
               arm1136j-s, arm1136jf-s, mpcore, mpcorenovfp, arm1156t2-s,
               arm1176jz-s, arm1176jzf-s, cortex-a8, cortex-a9, cortex-r4,
               cortex-r4f, cortex-m3, cortex-m1, xscale, iwmmxt, iwmmxt2, ep9312.
    
           -mtune=name
               This option is very similar to the -mcpu= option, except that
               instead of specifying the actual target processor type, and hence
               restricting which instructions can be used, it specifies that GCC
               should tune the performance of the code as if the target were of
               the type specified in this option, but still choosing the
               instructions that it will generate based on the cpu specified by a
               -mcpu= option.  For some ARM implementations better performance can
               be obtained by using this option.
    
           -march=name
               This specifies the name of the target ARM architecture.  GCC uses
               this name to determine what kind of instructions it can emit when
               generating assembly code.  This option can be used in conjunction
               with or instead of the -mcpu= option.  Permissible names are:
               armv2, armv2a, armv3, armv3m, armv4, armv4t, armv5, armv5t, armv5e,
               armv5te, armv6, armv6j, armv6t2, armv6z, armv6zk, armv6-m, armv7,
               armv7-a, armv7-r, armv7-m, iwmmxt, iwmmxt2, ep9312.
    
           -mfpu=name
           -mfpe=number
           -mfp=number
               This specifies what floating point hardware (or hardware emulation)
               is available on the target.  Permissible names are: fpa, fpe2,
               fpe3, maverick, vfp, vfpv3, vfpv3-d16 and neon.  -mfp and -mfpe are
               synonyms for -mfpu=fpenumber, for compatibility with older versions
               of GCC.
    
               If -msoft-float is specified this specifies the format of floating
               point values.
    
           -mstructure-size-boundary=n
               The size of all structures and unions will be rounded up to a
               multiple of the number of bits set by this option.  Permissible
               values are 8, 32 and 64.  The default value varies for different
               toolchains.  For the COFF targeted toolchain the default value is
               8.  A value of 64 is only allowed if the underlying ABI supports
               it.
    
               Specifying the larger number can produce faster, more efficient
               code, but can also increase the size of the program.  Different
               values are potentially incompatible.  Code compiled with one value
               range of the offset based version of subroutine call instruction.
    
               Even if this switch is enabled, not all function calls will be
               turned into long calls.  The heuristic is that static functions,
               functions which have the short-call attribute, functions that are
               inside the scope of a #pragma no_long_calls directive and functions
               whose definitions have already been compiled within the current
               compilation unit, will not be turned into long calls.  The
               exception to this rule is that weak function definitions, functions
               with the long-call attribute or the section attribute, and
               functions that are within the scope of a #pragma long_calls
               directive, will always be turned into long calls.
    
               This feature is not enabled by default.  Specifying -mno-long-calls
               will restore the default behavior, as will placing the function
               calls within the scope of a #pragma long_calls_off directive.  Note
               these switches have no effect on how the compiler generates code to
               handle function calls via function pointers.
    
           -msingle-pic-base
               Treat the register used for PIC addressing as read-only, rather
               than loading it in the prologue for each function.  The run-time
               system is responsible for initializing this register with an
               appropriate value before execution begins.
    
           -mpic-register=reg
               Specify the register to be used for PIC addressing.  The default is
               R10 unless stack-checking is enabled, when R9 is used.
    
           -mcirrus-fix-invalid-insns
               Insert NOPs into the instruction stream to in order to work around
               problems with invalid Maverick instruction combinations.  This
               option is only valid if the -mcpu=ep9312 option has been used to
               enable generation of instructions for the Cirrus Maverick floating
               point co-processor.  This option is not enabled by default, since
               the problem is only present in older Maverick implementations.  The
               default can be re-enabled by use of the
               -mno-cirrus-fix-invalid-insns switch.
    
           -mpoke-function-name
               Write the name of each function into the text section, directly
               preceding the function prologue.  The generated code is similar to
               this:
    
                            t0
                                .ascii "arm_poke_function_name", 0
                                .align
                            t1
                                .word 0xff000000 + (t1 - t0)
                            arm_poke_function_name
                                mov     ip, sp
                                stmfd   sp!, {fp, ip, lr, pc}
    
           -mtpcs-frame
               Generate a stack frame that is compliant with the Thumb Procedure
               Call Standard for all non-leaf functions.  (A leaf function is one
               that does not call any other functions.)  The default is
               -mno-tpcs-frame.
    
           -mtpcs-leaf-frame
               Generate a stack frame that is compliant with the Thumb Procedure
               Call Standard for all leaf functions.  (A leaf function is one that
               does not call any other functions.)  The default is
               -mno-apcs-leaf-frame.
    
           -mcallee-super-interworking
               Gives all externally visible functions in the file being compiled
               an ARM instruction set header which switches to Thumb mode before
               executing the rest of the function.  This allows these functions to
               be called from non-interworking code.
    
           -mcaller-super-interworking
               Allows calls via function pointers (including virtual functions) to
               execute correctly regardless of whether the target code has been
               compiled for interworking or not.  There is a small overhead in the
               cost of executing a function pointer if this option is enabled.
    
           -mtp=name
               Specify the access model for the thread local storage pointer.  The
               valid models are soft, which generates calls to "__aeabi_read_tp",
               cp15, which fetches the thread pointer from "cp15" directly
               (supported in the arm6k architecture), and auto, which uses the
               best available method for the selected processor.  The default
               setting is auto.
    
           -mword-relocations
               Only generate absolute relocations on word sized values (i.e.
               R_ARM_ABS32).  This is enabled by default on targets (uClinux,
               SymbianOS) where the runtime loader imposes this restriction, and
               when -fpic or -fPIC is specified.
    
       AVR Options
           These options are defined for AVR implementations:
    
           -mmcu=mcu
               Specify ATMEL AVR instruction set or MCU type.
    
               Instruction set avr1 is for the minimal AVR core, not supported by
               the C compiler, only for assembler programs (MCU types: at90s1200,
               attiny10, attiny11, attiny12, attiny15, attiny28).
    
               Instruction set avr2 (default) is for the classic AVR core with up
               to 8K program memory space (MCU types: at90s2313, at90s2323,
               attiny22, at90s2333, at90s2343, at90s4414, at90s4433, at90s4434,
               at90s8515, at90c8534, at90s8535).
    
           -mno-interrupts
               Generated code is not compatible with hardware interrupts.  Code
               size will be smaller.
    
           -mcall-prologues
               Functions prologues/epilogues expanded as call to appropriate
               subroutines.  Code size will be smaller.
    
           -mno-tablejump
               Do not generate tablejump insns which sometimes increase code size.
               The option is now deprecated in favor of the equivalent
               -fno-jump-tables
    
           -mtiny-stack
               Change only the low 8 bits of the stack pointer.
    
           -mint8
               Assume int to be 8 bit integer.  This affects the sizes of all
               types: A char will be 1 byte, an int will be 1 byte, an long will
               be 2 bytes and long long will be 4 bytes.  Please note that this
               option does not comply to the C standards, but it will provide you
               with smaller code size.
    
       Blackfin Options
           -mcpu=cpu[-sirevision]
               Specifies the name of the target Blackfin processor.  Currently,
               cpu can be one of bf512, bf514, bf516, bf518, bf522, bf523, bf524,
               bf525, bf526, bf527, bf531, bf532, bf533, bf534, bf536, bf537,
               bf538, bf539, bf542, bf544, bf547, bf548, bf549, bf561.  The
               optional sirevision specifies the silicon revision of the target
               Blackfin processor.  Any workarounds available for the targeted
               silicon revision will be enabled.  If sirevision is none, no
               workarounds are enabled.  If sirevision is any, all workarounds for
               the targeted processor will be enabled.  The "__SILICON_REVISION__"
               macro is defined to two hexadecimal digits representing the major
               and minor numbers in the silicon revision.  If sirevision is none,
               the "__SILICON_REVISION__" is not defined.  If sirevision is any,
               the "__SILICON_REVISION__" is defined to be 0xffff.  If this
               optional sirevision is not used, GCC assumes the latest known
               silicon revision of the targeted Blackfin processor.
    
               Support for bf561 is incomplete.  For bf561, Only the processor
               macro is defined.  Without this option, bf532 is used as the
               processor by default.  The corresponding predefined processor
               macros for cpu is to be defined.  And for bfin-elf toolchain, this
               causes the hardware BSP provided by libgloss to be linked in if
               -msim is not given.
    
           -msim
               Specifies that the program will be run on the simulator.  This
               causes the simulator BSP provided by libgloss to be linked in.
    
           -mno-specld-anomaly
               Don't generate extra code to prevent speculative loads from
               occurring.
    
           -mcsync-anomaly
               When enabled, the compiler will ensure that the generated code does
               not contain CSYNC or SSYNC instructions too soon after conditional
               branches.  If this option is used, "__WORKAROUND_SPECULATIVE_SYNCS"
               is defined.
    
           -mno-csync-anomaly
               Don't generate extra code to prevent CSYNC or SSYNC instructions
               from occurring too soon after a conditional branch.
    
           -mlow-64k
               When enabled, the compiler is free to take advantage of the
               knowledge that the entire program fits into the low 64k of memory.
    
           -mno-low-64k
               Assume that the program is arbitrarily large.  This is the default.
    
           -mstack-check-l1
               Do stack checking using information placed into L1 scratchpad
               memory by the uClinux kernel.
    
           -mid-shared-library
               Generate code that supports shared libraries via the library ID
               method.  This allows for execute in place and shared libraries in
               an environment without virtual memory management.  This option
               implies -fPIC.  With a bfin-elf target, this option implies -msim.
    
           -mno-id-shared-library
               Generate code that doesn't assume ID based shared libraries are
               being used.  This is the default.
    
           -mleaf-id-shared-library
               Generate code that supports shared libraries via the library ID
               method, but assumes that this library or executable won't link
               against any other ID shared libraries.  That allows the compiler to
               use faster code for jumps and calls.
    
           -mno-leaf-id-shared-library
               Do not assume that the code being compiled won't link against any
               ID shared libraries.  Slower code will be generated for jump and
               call insns.
    
           -mshared-library-id=n
               Specified the identification number of the ID based shared library
               being compiled.  Specifying a value of 0 will generate more compact
               code, specifying other values will force the allocation of that
               number to the current library but is no more space or time
               Tells the compiler to perform function calls by first loading the
               address of the function into a register and then performing a
               subroutine call on this register.  This switch is needed if the
               target function will lie outside of the 24 bit addressing range of
               the offset based version of subroutine call instruction.
    
               This feature is not enabled by default.  Specifying -mno-long-calls
               will restore the default behavior.  Note these switches have no
               effect on how the compiler generates code to handle function calls
               via function pointers.
    
           -mfast-fp
               Link with the fast floating-point library. This library relaxes
               some of the IEEE floating-point standard's rules for checking
               inputs against Not-a-Number (NAN), in the interest of performance.
    
           -minline-plt
               Enable inlining of PLT entries in function calls to functions that
               are not known to bind locally.  It has no effect without -mfdpic.
    
           -mmulticore
               Build standalone application for multicore Blackfin processor.
               Proper start files and link scripts will be used to support
               multicore.  This option defines "__BFIN_MULTICORE". It can only be
               used with -mcpu=bf561[-sirevision]. It can be used with -mcorea or
               -mcoreb. If it's used without -mcorea or -mcoreb, single
               application/dual core programming model is used. In this model, the
               main function of Core B should be named as coreb_main. If it's used
               with -mcorea or -mcoreb, one application per core programming model
               is used.  If this option is not used, single core application
               programming model is used.
    
           -mcorea
               Build standalone application for Core A of BF561 when using one
               application per core programming model. Proper start files and link
               scripts will be used to support Core A. This option defines
               "__BFIN_COREA". It must be used with -mmulticore.
    
           -mcoreb
               Build standalone application for Core B of BF561 when using one
               application per core programming model. Proper start files and link
               scripts will be used to support Core B. This option defines
               "__BFIN_COREB". When this option is used, coreb_main should be used
               instead of main. It must be used with -mmulticore.
    
           -msdram
               Build standalone application for SDRAM. Proper start files and link
               scripts will be used to put the application into SDRAM.  Loader
               should initialize SDRAM before loading the application into SDRAM.
               This option defines "__BFIN_SDRAM".
    
           -micplb
    
           -mtune=architecture-type
               Tune to architecture-type everything applicable about the generated
               code, except for the ABI and the set of available instructions.
               The choices for architecture-type are the same as for
               -march=architecture-type.
    
           -mmax-stack-frame=n
               Warn when the stack frame of a function exceeds n bytes.
    
           -metrax4
           -metrax100
               The options -metrax4 and -metrax100 are synonyms for -march=v3 and
               -march=v8 respectively.
    
           -mmul-bug-workaround
           -mno-mul-bug-workaround
               Work around a bug in the "muls" and "mulu" instructions for CPU
               models where it applies.  This option is active by default.
    
           -mpdebug
               Enable CRIS-specific verbose debug-related information in the
               assembly code.  This option also has the effect to turn off the
               #NO_APP formatted-code indicator to the assembler at the beginning
               of the assembly file.
    
           -mcc-init
               Do not use condition-code results from previous instruction; always
               emit compare and test instructions before use of condition codes.
    
           -mno-side-effects
               Do not emit instructions with side-effects in addressing modes
               other than post-increment.
    
           -mstack-align
           -mno-stack-align
           -mdata-align
           -mno-data-align
           -mconst-align
           -mno-const-align
               These options (no-options) arranges (eliminate arrangements) for
               the stack-frame, individual data and constants to be aligned for
               the maximum single data access size for the chosen CPU model.  The
               default is to arrange for 32-bit alignment.  ABI details such as
               structure layout are not affected by these options.
    
           -m32-bit
           -m16-bit
           -m8-bit
               Similar to the stack- data- and const-align options above, these
               options arrange for stack-frame, writable data and constants to all
               be 32-bit, 16-bit or 8-bit aligned.  The default is 32-bit
               sequences that load addresses for functions from the PLT part of
               the GOT rather than (traditional on other architectures) calls to
               the PLT.  The default is -mgotplt.
    
           -melf
               Legacy no-op option only recognized with the cris-axis-elf and
               cris-axis-linux-gnu targets.
    
           -mlinux
               Legacy no-op option only recognized with the cris-axis-linux-gnu
               target.
    
           -sim
               This option, recognized for the cris-axis-elf arranges to link with
               input-output functions from a simulator library.  Code, initialized
               data and zero-initialized data are allocated consecutively.
    
           -sim2
               Like -sim, but pass linker options to locate initialized data at
               0x40000000 and zero-initialized data at 0x80000000.
    
       CRX Options
           These options are defined specifically for the CRX ports.
    
           -mmac
               Enable the use of multiply-accumulate instructions. Disabled by
               default.
    
           -mpush-args
               Push instructions will be used to pass outgoing arguments when
               functions are called. Enabled by default.
    
       Darwin Options
           These options are defined for all architectures running the Darwin
           operating system.
    
           FSF GCC on Darwin does not create "fat" object files; it will create an
           object file for the single architecture that it was built to target.
           Apple's GCC on Darwin does create "fat" files if multiple -arch options
           are used; it does so by running the compiler or linker multiple times
           and joining the results together with lipo.
    
           The subtype of the file created (like ppc7400 or ppc970 or i686) is
           determined by the flags that specify the ISA that GCC is targetting,
           like -mcpu or -march.  The -force_cpusubtype_ALL option can be used to
           override this.
    
           The Darwin tools vary in their behavior when presented with an ISA
           mismatch.  The assembler, as, will only permit instructions to be used
           that are valid for the subtype of the file it is generating, so you
           cannot put 64-bit instructions in an ppc750 object file.  The linker
           for shared libraries, /usr/bin/libtool, will fail and print an error if
               name of a framework is the name of this directory excluding the
               ".framework".  Headers associated with the framework are found in
               one of those two directories, with "Headers" being searched first.
               A subframework is a framework directory that is in a framework's
               "Frameworks" directory.  Includes of subframework headers can only
               appear in a header of a framework that contains the subframework,
               or in a sibling subframework header.  Two subframeworks are
               siblings if they occur in the same framework.  A subframework
               should not have the same name as a framework, a warning will be
               issued if this is violated.  Currently a subframework cannot have
               subframeworks, in the future, the mechanism may be extended to
               support this.  The standard frameworks can be found in
               "/System/Library/Frameworks" and "/Library/Frameworks".  An example
               include looks like "#include <Framework/header.h>", where Framework
               denotes the name of the framework and header.h is found in the
               "PrivateHeaders" or "Headers" directory.
    
           -iframeworkdir
               Like -F except the directory is a treated as a system directory.
               The main difference between this -iframework and -F is that with
               -iframework the compiler does not warn about constructs contained
               within header files found via dir.  This option is valid only for
               the C family of languages.
    
           -gused
               Emit debugging information for symbols that are used.  For STABS
               debugging format, this enables -feliminate-unused-debug-symbols.
               This is by default ON.
    
           -gfull
               Emit debugging information for all symbols and types.
    
           -mmacosx-version-min=version
               The earliest version of MacOS X that this executable will run on is
               version.  Typical values of version include 10.1, 10.2, and 10.3.9.
    
               If the compiler was built to use the system's headers by default,
               then the default for this option is the system version on which the
               compiler is running, otherwise the default is to make choices which
               are compatible with as many systems and code bases as possible.
    
           -mkernel
               Enable kernel development mode.  The -mkernel option sets -static,
               -fno-common, -fno-cxa-atexit, -fno-exceptions,
               -fno-non-call-exceptions, -fapple-kext, -fno-weak and -fno-rtti
               where applicable.  This mode also sets -mno-altivec, -msoft-float,
               -fno-builtin and -mlong-branch for PowerPC targets.
    
           -mone-byte-bool
               Override the defaults for bool so that sizeof(bool)==1.  By default
               sizeof(bool) is 4 when compiling for Darwin/PowerPC and 1 when
               compiling for Darwin/x86, so this option has no effect on x86.
    
           -all_load
               Loads all members of static archive libraries.  See man ld(1) for
               more information.
    
           -arch_errors_fatal
               Cause the errors having to do with files that have the wrong
               architecture to be fatal.
    
           -bind_at_load
               Causes the output file to be marked such that the dynamic linker
               will bind all undefined references when the file is loaded or
               launched.
    
           -bundle
               Produce a Mach-o bundle format file.  See man ld(1) for more
               information.
    
           -bundle_loader executable
               This option specifies the executable that will be loading the build
               output file being linked.  See man ld(1) for more information.
    
           -dynamiclib
               When passed this option, GCC will produce a dynamic library instead
               of an executable when linking, using the Darwin libtool command.
    
           -force_cpusubtype_ALL
               This causes GCC's output file to have the ALL subtype, instead of
               one controlled by the -mcpu or -march option.
    
           -allowable_client  client_name
           -client_name
           -compatibility_version
           -current_version
           -dead_strip
           -dependency-file
           -dylib_file
           -dylinker_install_name
           -dynamic
           -exported_symbols_list
           -filelist
           -flat_namespace
           -force_flat_namespace
           -headerpad_max_install_names
           -image_base
           -init
           -install_name
           -keep_private_externs
           -multi_module
           -multiply_defined
           -multiply_defined_unused
           -noall_load
           -sectcreate
           -sectobjectsymbols
           -sectorder
           -segaddr
           -segs_read_only_addr
           -segs_read_write_addr
           -seg_addr_table
           -seg_addr_table_filename
           -seglinkedit
           -segprot
           -segs_read_only_addr
           -segs_read_write_addr
           -single_module
           -static
           -sub_library
           -sub_umbrella
           -twolevel_namespace
           -umbrella
           -undefined
           -unexported_symbols_list
           -weak_reference_mismatches
           -whatsloaded
               These options are passed to the Darwin linker.  The Darwin linker
               man page describes them in detail.
    
       DEC Alpha Options
           These -m options are defined for the DEC Alpha implementations:
    
           -mno-soft-float
           -msoft-float
               Use (do not use) the hardware floating-point instructions for
               floating-point operations.  When -msoft-float is specified,
               functions in libgcc.a will be used to perform floating-point
               operations.  Unless they are replaced by routines that emulate the
               floating-point operations, or compiled in such a way as to call
               such emulations routines, these routines will issue floating-point
               operations.   If you are compiling for an Alpha without floating-
               point operations, you must ensure that the library is built so as
               not to call them.
    
               Note that Alpha implementations without floating-point operations
               are required to have floating-point registers.
    
           -mfp-reg
           -mno-fp-regs
               Generate code that uses (does not use) the floating-point register
               set.  -mno-fp-regs implies -msoft-float.  If the floating-point
               register set is not used, floating point operands are passed in
               integer registers as if they were integers and floating-point
               results are passed in $0 instead of $f0.  This is a non-standard
               calling sequence, so any function with a floating-point argument or
               return value called by code compiled with -mno-fp-regs must also be
               less efficient but is able to correctly support denormalized
               numbers and exceptional IEEE values such as not-a-number and
               plus/minus infinity.  Other Alpha compilers call this option
               -ieee_with_no_inexact.
    
           -mieee-with-inexact
               This is like -mieee except the generated code also maintains the
               IEEE inexact-flag.  Turning on this option causes the generated
               code to implement fully-compliant IEEE math.  In addition to
               "_IEEE_FP", "_IEEE_FP_EXACT" is defined as a preprocessor macro.
               On some Alpha implementations the resulting code may execute
               significantly slower than the code generated by default.  Since
               there is very little code that depends on the inexact-flag, you
               should normally not specify this option.  Other Alpha compilers
               call this option -ieee_with_inexact.
    
           -mfp-trap-mode=trap-mode
               This option controls what floating-point related traps are enabled.
               Other Alpha compilers call this option -fptm trap-mode.  The trap
               mode can be set to one of four values:
    
               n   This is the default (normal) setting.  The only traps that are
                   enabled are the ones that cannot be disabled in software (e.g.,
                   division by zero trap).
    
               u   In addition to the traps enabled by n, underflow traps are
                   enabled as well.
    
               su  Like u, but the instructions are marked to be safe for software
                   completion (see Alpha architecture manual for details).
    
               sui Like su, but inexact traps are enabled as well.
    
           -mfp-rounding-mode=rounding-mode
               Selects the IEEE rounding mode.  Other Alpha compilers call this
               option -fprm rounding-mode.  The rounding-mode can be one of:
    
               n   Normal IEEE rounding mode.  Floating point numbers are rounded
                   towards the nearest machine number or towards the even machine
                   number in case of a tie.
    
               m   Round towards minus infinity.
    
               c   Chopped rounding mode.  Floating point numbers are rounded
                   towards zero.
    
               d   Dynamic rounding mode.  A field in the floating point control
                   register (fpcr, see Alpha architecture reference manual)
                   controls the rounding mode in effect.  The C library
                   initializes this register for rounding towards plus infinity.
                   Thus, unless your program modifies the fpcr, d corresponds to
                   round towards plus infinity.
    
               f   Function precision.  The trap handler can determine the
                   function that caused a floating point exception.
    
               i   Instruction precision.  The trap handler can determine the
                   exact instruction that caused a floating point exception.
    
               Other Alpha compilers provide the equivalent options called
               -scope_safe and -resumption_safe.
    
           -mieee-conformant
               This option marks the generated code as IEEE conformant.  You must
               not use this option unless you also specify -mtrap-precision=i and
               either -mfp-trap-mode=su or -mfp-trap-mode=sui.  Its only effect is
               to emit the line .eflag 48 in the function prologue of the
               generated assembly file.  Under DEC Unix, this has the effect that
               IEEE-conformant math library routines will be linked in.
    
           -mbuild-constants
               Normally GCC examines a 32- or 64-bit integer constant to see if it
               can construct it from smaller constants in two or three
               instructions.  If it cannot, it will output the constant as a
               literal and generate code to load it from the data segment at
               runtime.
    
               Use this option to require GCC to construct all integer constants
               using code, even if it takes more instructions (the maximum is
               six).
    
               You would typically use this option to build a shared library
               dynamic loader.  Itself a shared library, it must relocate itself
               in memory before it can find the variables and constants in its own
               data segment.
    
           -malpha-as
           -mgas
               Select whether to generate code to be assembled by the vendor-
               supplied assembler (-malpha-as) or by the GNU assembler -mgas.
    
           -mbwx
           -mno-bwx
           -mcix
           -mno-cix
           -mfix
           -mno-fix
           -mmax
           -mno-max
               Indicate whether GCC should generate code to use the optional BWX,
               CIX, FIX and MAX instruction sets.  The default is to use the
               instruction sets supported by the CPU type specified via -mcpu=
               option or that of the CPU on which GCC was built if none was
               specified.
    
               the default accordingly.
    
           -msmall-data
           -mlarge-data
               When -mexplicit-relocs is in effect, static data is accessed via
               gp-relative relocations.  When -msmall-data is used, objects 8
               bytes long or smaller are placed in a small data area (the ".sdata"
               and ".sbss" sections) and are accessed via 16-bit relocations off
               of the $gp register.  This limits the size of the small data area
               to 64KB, but allows the variables to be directly accessed via a
               single instruction.
    
               The default is -mlarge-data.  With this option the data area is
               limited to just below 2GB.  Programs that require more than 2GB of
               data must use "malloc" or "mmap" to allocate the data in the heap
               instead of in the program's data segment.
    
               When generating code for shared libraries, -fpic implies
               -msmall-data and -fPIC implies -mlarge-data.
    
           -msmall-text
           -mlarge-text
               When -msmall-text is used, the compiler assumes that the code of
               the entire program (or shared library) fits in 4MB, and is thus
               reachable with a branch instruction.  When -msmall-data is used,
               the compiler can assume that all local symbols share the same $gp
               value, and thus reduce the number of instructions required for a
               function call from 4 to 1.
    
               The default is -mlarge-text.
    
           -mcpu=cpu_type
               Set the instruction set and instruction scheduling parameters for
               machine type cpu_type.  You can specify either the EV style name or
               the corresponding chip number.  GCC supports scheduling parameters
               for the EV4, EV5 and EV6 family of processors and will choose the
               default values for the instruction set from the processor you
               specify.  If you do not specify a processor type, GCC will default
               to the processor on which the compiler was built.
    
               Supported values for cpu_type are
    
               ev4
               ev45
               21064
                   Schedules as an EV4 and has no instruction set extensions.
    
               ev5
               21164
                   Schedules as an EV5 and has no instruction set extensions.
    
               ev56
               21264a
                   Schedules as an EV6 and supports the BWX, CIX, FIX, and MAX
                   extensions.
    
               Native Linux/GNU toolchains also support the value native, which
               selects the best architecture option for the host processor.
               -mcpu=native has no effect if GCC does not recognize the processor.
    
           -mtune=cpu_type
               Set only the instruction scheduling parameters for machine type
               cpu_type.  The instruction set is not changed.
    
               Native Linux/GNU toolchains also support the value native, which
               selects the best architecture option for the host processor.
               -mtune=native has no effect if GCC does not recognize the
               processor.
    
           -mmemory-latency=time
               Sets the latency the scheduler should assume for typical memory
               references as seen by the application.  This number is highly
               dependent on the memory access patterns used by the application and
               the size of the external cache on the machine.
    
               Valid options for time are
    
               number
                   A decimal number representing clock cycles.
    
               L1
               L2
               L3
               main
                   The compiler contains estimates of the number of clock cycles
                   for "typical" EV4 & EV5 hardware for the Level 1, 2 & 3 caches
                   (also called Dcache, Scache, and Bcache), as well as to main
                   memory.  Note that L3 is only valid for EV5.
    
       DEC Alpha/VMS Options
           These -m options are defined for the DEC Alpha/VMS implementations:
    
           -mvms-return-codes
               Return VMS condition codes from main.  The default is to return
               POSIX style condition (e.g. error) codes.
    
       FR30 Options
           These options are defined specifically for the FR30 port.
    
           -msmall-model
               Use the small address space model.  This can produce smaller code,
               but it does assume that all symbolic values and addresses will fit
               into a 20-bit range.
    
    
           -mfpr-64
               Use all 64 floating point registers
    
           -mhard-float
               Use hardware instructions for floating point operations.
    
           -msoft-float
               Use library routines for floating point operations.
    
           -malloc-cc
               Dynamically allocate condition code registers.
    
           -mfixed-cc
               Do not try to dynamically allocate condition code registers, only
               use "icc0" and "fcc0".
    
           -mdword
               Change ABI to use double word insns.
    
           -mno-dword
               Do not use double word instructions.
    
           -mdouble
               Use floating point double instructions.
    
           -mno-double
               Do not use floating point double instructions.
    
           -mmedia
               Use media instructions.
    
           -mno-media
               Do not use media instructions.
    
           -mmuladd
               Use multiply and add/subtract instructions.
    
           -mno-muladd
               Do not use multiply and add/subtract instructions.
    
           -mfdpic
               Select the FDPIC ABI, that uses function descriptors to represent
               pointers to functions.  Without any PIC/PIE-related options, it
               implies -fPIE.  With -fpic or -fpie, it assumes GOT entries and
               small data are within a 12-bit range from the GOT base address;
               with -fPIC or -fPIE, GOT offsets are computed with 32 bits.  With a
               bfin-elf target, this option implies -msim.
    
           -minline-plt
               Enable inlining of PLT entries in function calls to functions that
               are not known to bind locally.  It has no effect without -mfdpic.
               default, except for -fpic or -fpie: even though it may help make
               the global offset table smaller, it trades 1 instruction for 4.
               With -fPIC or -fPIE, it trades 3 instructions for 4, one of which
               may be shared by multiple symbols, and it avoids the need for a GOT
               entry for the referenced symbol, so it's more likely to be a win.
               If it is not, -mno-gprel-ro can be used to disable it.
    
           -multilib-library-pic
               Link with the (library, not FD) pic libraries.  It's implied by
               -mlibrary-pic, as well as by -fPIC and -fpic without -mfdpic.  You
               should never have to use it explicitly.
    
           -mlinked-fp
               Follow the EABI requirement of always creating a frame pointer
               whenever a stack frame is allocated.  This option is enabled by
               default and can be disabled with -mno-linked-fp.
    
           -mlong-calls
               Use indirect addressing to call functions outside the current
               compilation unit.  This allows the functions to be placed anywhere
               within the 32-bit address space.
    
           -malign-labels
               Try to align labels to an 8-byte boundary by inserting nops into
               the previous packet.  This option only has an effect when VLIW
               packing is enabled.  It doesn't create new packets; it merely adds
               nops to existing ones.
    
           -mlibrary-pic
               Generate position-independent EABI code.
    
           -macc-4
               Use only the first four media accumulator registers.
    
           -macc-8
               Use all eight media accumulator registers.
    
           -mpack
               Pack VLIW instructions.
    
           -mno-pack
               Do not pack VLIW instructions.
    
           -mno-eflags
               Do not mark ABI switches in e_flags.
    
           -mcond-move
               Enable the use of conditional-move instructions (default).
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mcond-exec
               Enable the use of conditional execution (default).
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mno-cond-exec
               Disable the use of conditional execution.
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mvliw-branch
               Run a pass to pack branches into VLIW instructions (default).
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mno-vliw-branch
               Do not run a pass to pack branches into VLIW instructions.
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mmulti-cond-exec
               Enable optimization of "&&" and "||" in conditional execution
               (default).
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mno-multi-cond-exec
               Disable optimization of "&&" and "||" in conditional execution.
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mnested-cond-exec
               Enable nested conditional execution optimizations (default).
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
    
           -mno-nested-cond-exec
               Disable nested conditional execution optimizations.
    
               This switch is mainly for debugging the compiler and will likely be
               removed in a future version.
               values are frv, fr550, tomcat, fr500, fr450, fr405, fr400, fr300
               and simple.
    
       GNU/Linux Options
           These -m options are defined for GNU/Linux targets:
    
           -mglibc
               Use the GNU C library instead of uClibc.  This is the default
               except on *-*-linux-*uclibc* targets.
    
           -muclibc
               Use uClibc instead of the GNU C library.  This is the default on
               *-*-linux-*uclibc* targets.
    
       H8/300 Options
           These -m options are defined for the H8/300 implementations:
    
           -mrelax
               Shorten some address references at link time, when possible; uses
               the linker option -relax.
    
           -mh Generate code for the H8/300H.
    
           -ms Generate code for the H8S.
    
           -mn Generate code for the H8S and H8/300H in the normal mode.  This
               switch must be used either with -mh or -ms.
    
           -ms2600
               Generate code for the H8S/2600.  This switch must be used with -ms.
    
           -mint32
               Make "int" data 32 bits by default.
    
           -malign-300
               On the H8/300H and H8S, use the same alignment rules as for the
               H8/300.  The default for the H8/300H and H8S is to align longs and
               floats on 4 byte boundaries.  -malign-300 causes them to be aligned
               on 2 byte boundaries.  This option has no effect on the H8/300.
    
       HPPA Options
           These -m options are defined for the HPPA family of computers:
    
           -march=architecture-type
               Generate code for the specified architecture.  The choices for
               architecture-type are 1.0 for PA 1.0, 1.1 for PA 1.1, and 2.0 for
               PA 2.0 processors.  Refer to /usr/lib/sched.models on an HP-UX
               system to determine the proper architecture option for your
               machine.  Code compiled for lower numbered architectures will run
               on higher numbered architectures, but not the other way around.
    
           -mpa-risc-1-0
           -mdisable-fpregs
               Prevent floating point registers from being used in any manner.
               This is necessary for compiling kernels which perform lazy context
               switching of floating point registers.  If you use this option and
               attempt to perform floating point operations, the compiler will
               abort.
    
           -mdisable-indexing
               Prevent the compiler from using indexing address modes.  This
               avoids some rather obscure problems when compiling MIG generated
               code under MACH.
    
           -mno-space-regs
               Generate code that assumes the target has no space registers.  This
               allows GCC to generate faster indirect calls and use unscaled index
               address modes.
    
               Such code is suitable for level 0 PA systems and kernels.
    
           -mfast-indirect-calls
               Generate code that assumes calls never cross space boundaries.
               This allows GCC to emit code which performs faster indirect calls.
    
               This option will not work in the presence of shared libraries or
               nested functions.
    
           -mfixed-range=register-range
               Generate code treating the given register range as fixed registers.
               A fixed register is one that the register allocator can not use.
               This is useful when compiling kernel code.  A register range is
               specified as two registers separated by a dash.  Multiple register
               ranges can be specified separated by a comma.
    
           -mlong-load-store
               Generate 3-instruction load and store sequences as sometimes
               required by the HP-UX 10 linker.  This is equivalent to the +k
               option to the HP compilers.
    
           -mportable-runtime
               Use the portable calling conventions proposed by HP for ELF
               systems.
    
           -mgas
               Enable the use of assembler directives only GAS understands.
    
           -mschedule=cpu-type
               Schedule code according to the constraints for the machine type
               cpu-type.  The choices for cpu-type are 700 7100, 7100LC, 7200,
               7300 and 8000.  Refer to /usr/lib/sched.models on an HP-UX system
               to determine the proper scheduling option for your machine.  The
               default scheduling is 8000.
    
               -msoft-float changes the calling convention in the output file;
               therefore, it is only useful if you compile all of a program with
               this option.  In particular, you need to compile libgcc.a, the
               library that comes with GCC, with -msoft-float in order for this to
               work.
    
           -msio
               Generate the predefine, "_SIO", for server IO.  The default is
               -mwsio.  This generates the predefines, "__hp9000s700",
               "__hp9000s700__" and "_WSIO", for workstation IO.  These options
               are available under HP-UX and HI-UX.
    
           -mgnu-ld
               Use GNU ld specific options.  This passes -shared to ld when
               building a shared library.  It is the default when GCC is
               configured, explicitly or implicitly, with the GNU linker.  This
               option does not have any affect on which ld is called, it only
               changes what parameters are passed to that ld.  The ld that is
               called is determined by the --with-ld configure option, GCC's
               program search path, and finally by the user's PATH.  The linker
               used by GCC can be printed using which 'gcc -print-prog-name=ld'.
               This option is only available on the 64 bit HP-UX GCC, i.e.
               configured with hppa*64*-*-hpux*.
    
           -mhp-ld
               Use HP ld specific options.  This passes -b to ld when building a
               shared library and passes +Accept TypeMismatch to ld on all links.
               It is the default when GCC is configured, explicitly or implicitly,
               with the HP linker.  This option does not have any affect on which
               ld is called, it only changes what parameters are passed to that
               ld.  The ld that is called is determined by the --with-ld configure
               option, GCC's program search path, and finally by the user's PATH.
               The linker used by GCC can be printed using which 'gcc
               -print-prog-name=ld'.  This option is only available on the 64 bit
               HP-UX GCC, i.e. configured with hppa*64*-*-hpux*.
    
           -mlong-calls
               Generate code that uses long call sequences.  This ensures that a
               call is always able to reach linker generated stubs.  The default
               is to generate long calls only when the distance from the call site
               to the beginning of the function or translation unit, as the case
               may be, exceeds a predefined limit set by the branch type being
               used.  The limits for normal calls are 7,600,000 and 240,000 bytes,
               respectively for the PA 2.0 and PA 1.X architectures.  Sibcalls are
               always limited at 240,000 bytes.
    
               Distances are measured from the beginning of functions when using
               the -ffunction-sections option, or when using the -mgas and
               -mno-portable-runtime options together under HP-UX with the SOM
               linker.
    
               It is normally not desirable to use this option as it will degrade
               UX 10.10 and later.  98 is available on HP-UX 11.11 and later.  The
               default values are 93 for HP-UX 10.00, 95 for HP-UX 10.10 though to
               11.00, and 98 for HP-UX 11.11 and later.
    
               -munix=93 provides the same predefines as GCC 3.3 and 3.4.
               -munix=95 provides additional predefines for "XOPEN_UNIX" and
               "_XOPEN_SOURCE_EXTENDED", and the startfile unix95.o.  -munix=98
               provides additional predefines for "_XOPEN_UNIX",
               "_XOPEN_SOURCE_EXTENDED", "_INCLUDE__STDC_A1_SOURCE" and
               "_INCLUDE_XOPEN_SOURCE_500", and the startfile unix98.o.
    
               It is important to note that this option changes the interfaces for
               various library routines.  It also affects the operational behavior
               of the C library.  Thus, extreme care is needed in using this
               option.
    
               Library code that is intended to operate with more than one UNIX
               standard must test, set and restore the variable
               __xpg4_extended_mask as appropriate.  Most GNU software doesn't
               provide this capability.
    
           -nolibdld
               Suppress the generation of link options to search libdld.sl when
               the -static option is specified on HP-UX 10 and later.
    
           -static
               The HP-UX implementation of setlocale in libc has a dependency on
               libdld.sl.  There isn't an archive version of libdld.sl.  Thus,
               when the -static option is specified, special link options are
               needed to resolve this dependency.
    
               On HP-UX 10 and later, the GCC driver adds the necessary options to
               link with libdld.sl when the -static option is specified.  This
               causes the resulting binary to be dynamic.  On the 64-bit port, the
               linkers generate dynamic binaries by default in any case.  The
               -nolibdld option can be used to prevent the GCC driver from adding
               these link options.
    
           -threads
               Add support for multithreading with the dce thread library under
               HP-UX.  This option sets flags for both the preprocessor and
               linker.
    
       Intel 386 and AMD x86-64 Options
           These -m options are defined for the i386 and x86-64 family of
           computers:
    
           -mtune=cpu-type
               Tune to cpu-type everything applicable about the generated code,
               except for the ABI and the set of available instructions.  The
               choices for cpu-type are:
    
                   instruction set the compiler can use, and there is no generic
                   instruction set applicable to all processors.  In contrast,
                   -mtune indicates the processor (or, in this case, collection of
                   processors) for which the code is optimized.
    
               native
                   This selects the CPU to tune for at compilation time by
                   determining the processor type of the compiling machine.  Using
                   -mtune=native will produce code optimized for the local machine
                   under the constraints of the selected instruction set.  Using
                   -march=native will enable all instruction subsets supported by
                   the local machine (hence the result might not run on different
                   machines).
    
               i386
                   Original Intel's i386 CPU.
    
               i486
                   Intel's i486 CPU.  (No scheduling is implemented for this
                   chip.)
    
               i586, pentium
                   Intel Pentium CPU with no MMX support.
    
               pentium-mmx
                   Intel PentiumMMX CPU based on Pentium core with MMX instruction
                   set support.
    
               pentiumpro
                   Intel PentiumPro CPU.
    
               i686
                   Same as "generic", but when used as "march" option, PentiumPro
                   instruction set will be used, so the code will run on all i686
                   family chips.
    
               pentium2
                   Intel Pentium2 CPU based on PentiumPro core with MMX
                   instruction set support.
    
               pentium3, pentium3m
                   Intel Pentium3 CPU based on PentiumPro core with MMX and SSE
                   instruction set support.
    
               pentium-m
                   Low power version of Intel Pentium3 CPU with MMX, SSE and SSE2
                   instruction set support.  Used by Centrino notebooks.
    
               pentium4, pentium4m
                   Intel Pentium4 CPU with MMX, SSE and SSE2 instruction set
                   support.
    
               k6-2, k6-3
                   Improved versions of AMD K6 CPU with MMX and 3dNOW! instruction
                   set support.
    
               athlon, athlon-tbird
                   AMD Athlon CPU with MMX, 3dNOW!, enhanced 3dNOW! and SSE
                   prefetch instructions support.
    
               athlon-4, athlon-xp, athlon-mp
                   Improved AMD Athlon CPU with MMX, 3dNOW!, enhanced 3dNOW! and
                   full SSE instruction set support.
    
               k8, opteron, athlon64, athlon-fx
                   AMD K8 core based CPUs with x86-64 instruction set support.
                   (This supersets MMX, SSE, SSE2, 3dNOW!, enhanced 3dNOW! and
                   64-bit instruction set extensions.)
    
               k8-sse3, opteron-sse3, athlon64-sse3
                   Improved versions of k8, opteron and athlon64 with SSE3
                   instruction set support.
    
               amdfam10, barcelona
                   AMD Family 10h core based CPUs with x86-64 instruction set
                   support.  (This supersets MMX, SSE, SSE2, SSE3, SSE4A, 3dNOW!,
                   enhanced 3dNOW!, ABM and 64-bit instruction set extensions.)
    
               winchip-c6
                   IDT Winchip C6 CPU, dealt in same way as i486 with additional
                   MMX instruction set support.
    
               winchip2
                   IDT Winchip2 CPU, dealt in same way as i486 with additional MMX
                   and 3dNOW!  instruction set support.
    
               c3  Via C3 CPU with MMX and 3dNOW! instruction set support.  (No
                   scheduling is implemented for this chip.)
    
               c3-2
                   Via C3-2 CPU with MMX and SSE instruction set support.  (No
                   scheduling is implemented for this chip.)
    
               geode
                   Embedded AMD CPU with MMX and 3dNOW! instruction set support.
    
               While picking a specific cpu-type will schedule things
               appropriately for that particular chip, the compiler will not
               generate any code that does not run on the i386 without the
               -march=cpu-type option being used.
    
           -march=cpu-type
               Generate instructions for the machine type cpu-type.  The choices
               for cpu-type are the same as for -mtune.  Moreover, specifying
                   most of other chips.  See -ffloat-store for more detailed
                   description.
    
                   This is the default choice for i386 compiler.
    
               sse Use scalar floating point instructions present in the SSE
                   instruction set.  This instruction set is supported by Pentium3
                   and newer chips, in the AMD line by Athlon-4, Athlon-xp and
                   Athlon-mp chips.  The earlier version of SSE instruction set
                   supports only single precision arithmetics, thus the double and
                   extended precision arithmetics is still done using 387.  Later
                   version, present only in Pentium4 and the future AMD x86-64
                   chips supports double precision arithmetics too.
    
                   For the i386 compiler, you need to use -march=cpu-type, -msse
                   or -msse2 switches to enable SSE extensions and make this
                   option effective.  For the x86-64 compiler, these extensions
                   are enabled by default.
    
                   The resulting code should be considerably faster in the
                   majority of cases and avoid the numerical instability problems
                   of 387 code, but may break some existing code that expects
                   temporaries to be 80bit.
    
                   This is the default choice for the x86-64 compiler.
    
               sse,387
               sse+387
               both
                   Attempt to utilize both instruction sets at once.  This
                   effectively double the amount of available registers and on
                   chips with separate execution units for 387 and SSE the
                   execution resources too.  Use this option with care, as it is
                   still experimental, because the GCC register allocator does not
                   model separate functional units well resulting in instable
                   performance.
    
           -masm=dialect
               Output asm instructions using selected dialect.  Supported choices
               are intel or att (the default one).  Darwin does not support intel.
    
           -mieee-fp
           -mno-ieee-fp
               Control whether or not the compiler uses IEEE floating point
               comparisons.  These handle correctly the case where the result of a
               comparison is unordered.
    
           -msoft-float
               Generate output containing library calls for floating point.
               Warning: the requisite libraries are not part of GCC.  Normally the
               facilities of the machine's usual C compiler are used, but this
               can't be done directly in cross-compilation.  You must make your
               The option -mno-fp-ret-in-387 causes such values to be returned in
               ordinary CPU registers instead.
    
           -mno-fancy-math-387
               Some 387 emulators do not support the "sin", "cos" and "sqrt"
               instructions for the 387.  Specify this option to avoid generating
               those instructions.  This option is the default on FreeBSD, OpenBSD
               and NetBSD.  This option is overridden when -march indicates that
               the target cpu will always have an FPU and so the instruction will
               not need emulation.  As of revision 2.6.1, these instructions are
               not generated unless you also use the -funsafe-math-optimizations
               switch.
    
           -malign-double
           -mno-align-double
               Control whether GCC aligns "double", "long double", and "long long"
               variables on a two word boundary or a one word boundary.  Aligning
               "double" variables on a two word boundary will produce code that
               runs somewhat faster on a Pentium at the expense of more memory.
    
               On x86-64, -malign-double is enabled by default.
    
               Warning: if you use the -malign-double switch, structures
               containing the above types will be aligned differently than the
               published application binary interface specifications for the 386
               and will not be binary compatible with structures in code compiled
               without that switch.
    
           -m96bit-long-double
           -m128bit-long-double
               These switches control the size of "long double" type.  The i386
               application binary interface specifies the size to be 96 bits, so
               -m96bit-long-double is the default in 32 bit mode.
    
               Modern architectures (Pentium and newer) would prefer "long double"
               to be aligned to an 8 or 16 byte boundary.  In arrays or structures
               conforming to the ABI, this would not be possible.  So specifying a
               -m128bit-long-double will align "long double" to a 16 byte boundary
               by padding the "long double" with an additional 32 bit zero.
    
               In the x86-64 compiler, -m128bit-long-double is the default choice
               as its ABI specifies that "long double" is to be aligned on 16 byte
               boundary.
    
               Notice that neither of these options enable any extra precision
               over the x87 standard of 80 bits for a "long double".
    
               Warning: if you override the default value for your target ABI, the
               structures and arrays containing "long double" variables will
               change their size as well as function calling convention for
               function taking "long double" will be modified.  Hence they will
               not be binary compatible with arrays or structures in code compiled
               You can specify that an individual function is called with this
               calling sequence with the function attribute stdcall.  You can also
               override the -mrtd option by using the function attribute cdecl.
    
               Warning: this calling convention is incompatible with the one
               normally used on Unix, so you cannot use it if you need to call
               libraries compiled with the Unix compiler.
    
               Also, you must provide function prototypes for all functions that
               take variable numbers of arguments (including "printf"); otherwise
               incorrect code will be generated for calls to those functions.
    
               In addition, seriously incorrect code will result if you call a
               function with too many arguments.  (Normally, extra arguments are
               harmlessly ignored.)
    
           -mregparm=num
               Control how many registers are used to pass integer arguments.  By
               default, no registers are used to pass arguments, and at most 3
               registers can be used.  You can control this behavior for a
               specific function by using the function attribute regparm.
    
               Warning: if you use this switch, and num is nonzero, then you must
               build all modules with the same value, including any libraries.
               This includes the system libraries and startup modules.
    
           -msseregparm
               Use SSE register passing conventions for float and double arguments
               and return values.  You can control this behavior for a specific
               function by using the function attribute sseregparm.
    
               Warning: if you use this switch then you must build all modules
               with the same value, including any libraries.  This includes the
               system libraries and startup modules.
    
           -mpc32
           -mpc64
           -mpc80
               Set 80387 floating-point precision to 32, 64 or 80 bits.  When
               -mpc32 is specified, the significands of results of floating-point
               operations are rounded to 24 bits (single precision); -mpc64 rounds
               the significands of results of floating-point operations to 53 bits
               (double precision) and -mpc80 rounds the significands of results of
               floating-point operations to 64 bits (extended double precision),
               which is the default.  When this option is used, floating-point
               operations in higher precisions are not available to the programmer
               without setting the FPU control word explicitly.
    
               Setting the rounding of floating-point operations to less than the
               default 80 bits can speed some programs by 2% or more.  Note that
               some mathematical libraries assume that extended precision (80 bit)
               floating-point operations are enabled by default; routines in such
               Attempt to keep the stack boundary aligned to a 2 raised to num
               byte boundary.  If -mpreferred-stack-boundary is not specified, the
               default is 4 (16 bytes or 128 bits).
    
           -mincoming-stack-boundary=num
               Assume the incoming stack is aligned to a 2 raised to num byte
               boundary.  If -mincoming-stack-boundary is not specified, the one
               specified by -mpreferred-stack-boundary will be used.
    
               On Pentium and PentiumPro, "double" and "long double" values should
               be aligned to an 8 byte boundary (see -malign-double) or suffer
               significant run time performance penalties.  On Pentium III, the
               Streaming SIMD Extension (SSE) data type "__m128" may not work
               properly if it is not 16 byte aligned.
    
               To ensure proper alignment of this values on the stack, the stack
               boundary must be as aligned as that required by any value stored on
               the stack.  Further, every function must be generated such that it
               keeps the stack aligned.  Thus calling a function compiled with a
               higher preferred stack boundary from a function compiled with a
               lower preferred stack boundary will most likely misalign the stack.
               It is recommended that libraries that use callbacks always use the
               default setting.
    
               This extra alignment does consume extra stack space, and generally
               increases code size.  Code that is sensitive to stack space usage,
               such as embedded systems and operating system kernels, may want to
               reduce the preferred alignment to -mpreferred-stack-boundary=2.
    
           -mmmx
           -mno-mmx
           -msse
           -mno-sse
           -msse2
           -mno-sse2
           -msse3
           -mno-sse3
           -mssse3
           -mno-ssse3
           -msse4.1
           -mno-sse4.1
           -msse4.2
           -mno-sse4.2
           -msse4
           -mno-sse4
           -mavx
           -mno-avx
           -maes
           -mno-aes
           -mpclmul
           -mno-pclmul
           -mfsgsbase
           -mno-3dnow
           -mpopcnt
           -mno-popcnt
           -mabm
           -mno-abm
           -mbmi
           -mno-bmi
           -mtbm
           -mno-tbm
               These switches enable or disable the use of instructions in the
               MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, FSGSBASE,
               RDRND, F16C, SSE4A, FMA4, XOP, LWP, ABM, BMI, or 3DNow! extended
               instruction sets.  These extensions are also available as built-in
               functions: see X86 Built-in Functions, for details of the functions
               enabled and disabled by these switches.
    
               To have SSE/SSE2 instructions generated automatically from
               floating-point code (as opposed to 387 instructions), see
               -mfpmath=sse.
    
               GCC depresses SSEx instructions when -mavx is used. Instead, it
               generates new AVX instructions or AVX equivalence for all SSEx
               instructions when needed.
    
               These options will enable GCC to use these extended instructions in
               generated code, even without -mfpmath=sse.  Applications which
               perform runtime CPU detection must compile separate files for each
               supported architecture, using the appropriate flags.  In
               particular, the file containing the CPU detection code should be
               compiled without these options.
    
           -mfused-madd
           -mno-fused-madd
               Do (don't) generate code that uses the fused multiply/add or
               multiply/subtract instructions.  The default is to use these
               instructions.
    
           -mcld
               This option instructs GCC to emit a "cld" instruction in the
               prologue of functions that use string instructions.  String
               instructions depend on the DF flag to select between autoincrement
               or autodecrement mode.  While the ABI specifies the DF flag to be
               cleared on function entry, some operating systems violate this
               specification by not clearing the DF flag in their exception
               dispatchers.  The exception handler can be invoked with the DF flag
               set which leads to wrong direction mode, when string instructions
               are used.  This option can be enabled by default on 32-bit x86
               targets by configuring GCC with the --enable-cld configure option.
               Generation of "cld" instructions can be suppressed with the
               -mno-cld compiler option in this case.
    
           -mcx16
               "remainder" built-in functions: see Other Builtins for details.
    
           -mmovbe
               This option will enable GCC to use movbe instruction to implement
               "__builtin_bswap32" and "__builtin_bswap64".
    
           -mcrc32
               This option will enable built-in functions,
               "__builtin_ia32_crc32qi", "__builtin_ia32_crc32hi".
               "__builtin_ia32_crc32si" and "__builtin_ia32_crc32di" to generate
               the crc32 machine instruction.
    
           -mrecip
               This option will enable GCC to use RCPSS and RSQRTSS instructions
               (and their vectorized variants RCPPS and RSQRTPS) with an
               additional Newton-Raphson step to increase precision instead of
               DIVSS and SQRTSS (and their vectorized variants) for single
               precision floating point arguments.  These instructions are
               generated only when -funsafe-math-optimizations is enabled together
               with -finite-math-only and -fno-trapping-math.  Note that while the
               throughput of the sequence is higher than the throughput of the
               non-reciprocal instruction, the precision of the sequence can be
               decreased by up to 2 ulp (i.e. the inverse of 1.0 equals
               0.99999994).
    
           -mveclibabi=type
               Specifies the ABI type to use for vectorizing intrinsics using an
               external library.  Supported types are "svml" for the Intel short
               vector math library and "acml" for the AMD math core library style
               of interfacing.  GCC will currently emit calls to "vmldExp2",
               "vmldLn2", "vmldLog102", "vmldLog102", "vmldPow2", "vmldTanh2",
               "vmldTan2", "vmldAtan2", "vmldAtanh2", "vmldCbrt2", "vmldSinh2",
               "vmldSin2", "vmldAsinh2", "vmldAsin2", "vmldCosh2", "vmldCos2",
               "vmldAcosh2", "vmldAcos2", "vmlsExp4", "vmlsLn4", "vmlsLog104",
               "vmlsLog104", "vmlsPow4", "vmlsTanh4", "vmlsTan4", "vmlsAtan4",
               "vmlsAtanh4", "vmlsCbrt4", "vmlsSinh4", "vmlsSin4", "vmlsAsinh4",
               "vmlsAsin4", "vmlsCosh4", "vmlsCos4", "vmlsAcosh4" and "vmlsAcos4"
               for corresponding function type when -mveclibabi=svml is used and
               "__vrd2_sin", "__vrd2_cos", "__vrd2_exp", "__vrd2_log",
               "__vrd2_log2", "__vrd2_log10", "__vrs4_sinf", "__vrs4_cosf",
               "__vrs4_expf", "__vrs4_logf", "__vrs4_log2f", "__vrs4_log10f" and
               "__vrs4_powf" for corresponding function type when -mveclibabi=acml
               is used. Both -ftree-vectorize and -funsafe-math-optimizations have
               to be enabled. A SVML or ACML ABI compatible library will have to
               be specified at link time.
    
           -mpush-args
           -mno-push-args
               Use PUSH operations to store outgoing parameters.  This method is
               shorter and usually equally fast as method using SUB/MOV operations
               and is enabled by default.  In some cases disabling it may improve
               performance because of improved scheduling and reduced
               -D_MT; when linking, it links in a special thread helper library
               -lmingwthrd which cleans up per thread exception handling data.
    
           -mno-align-stringops
               Do not align destination of inlined string operations.  This switch
               reduces code size and improves performance in case the destination
               is already aligned, but GCC doesn't know about it.
    
           -minline-all-stringops
               By default GCC inlines string operations only when destination is
               known to be aligned at least to 4 byte boundary.  This enables more
               inlining, increase code size, but may improve performance of code
               that depends on fast memcpy, strlen and memset for short lengths.
    
           -minline-stringops-dynamically
               For string operation of unknown size, inline runtime checks so for
               small blocks inline code is used, while for large blocks library
               call is used.
    
           -mstringop-strategy=alg
               Overwrite internal decision heuristic about particular algorithm to
               inline string operation with.  The allowed values are "rep_byte",
               "rep_4byte", "rep_8byte" for expanding using i386 "rep" prefix of
               specified size, "byte_loop", "loop", "unrolled_loop" for expanding
               inline loop, "libcall" for always expanding library call.
    
           -momit-leaf-frame-pointer
               Don't keep the frame pointer in a register for leaf functions.
               This avoids the instructions to save, set up and restore frame
               pointers and makes an extra register available in leaf functions.
               The option -fomit-frame-pointer removes the frame pointer for all
               functions which might make debugging harder.
    
           -mtls-direct-seg-refs
           -mno-tls-direct-seg-refs
               Controls whether TLS variables may be accessed with offsets from
               the TLS segment register (%gs for 32-bit, %fs for 64-bit), or
               whether the thread base pointer must be added.  Whether or not this
               is legal depends on the operating system, and whether it maps the
               segment to cover the entire TLS area.
    
               For systems that use GNU libc, the default is on.
    
           -msse2avx
           -mno-sse2avx
               Specify that the assembler should encode SSE instructions with VEX
               prefix.  The option -mavx turns this on by default.
    
           These -m switches are supported in addition to the above on AMD x86-64
           processors in 64-bit environments.
    
           -m32
               disables this red zone.
    
           -mcmodel=small
               Generate code for the small code model: the program and its symbols
               must be linked in the lower 2 GB of the address space.  Pointers
               are 64 bits.  Programs can be statically or dynamically linked.
               This is the default code model.
    
           -mcmodel=kernel
               Generate code for the kernel code model.  The kernel runs in the
               negative 2 GB of the address space.  This model has to be used for
               Linux kernel code.
    
           -mcmodel=medium
               Generate code for the medium model: The program is linked in the
               lower 2 GB of the address space.  Small symbols are also placed
               there.  Symbols with sizes larger than -mlarge-data-threshold are
               put into large data or bss sections and can be located above 2GB.
               Programs can be statically or dynamically linked.
    
           -mcmodel=large
               Generate code for the large model: This model makes no assumptions
               about addresses and sizes of sections.
    
       i386 and x86-64 Windows Options
           These additional options are available for Windows targets:
    
           -mconsole
               This option is available for Cygwin and MinGW targets.  It
               specifies that a console application is to be generated, by
               instructing the linker to set the PE header subsystem type required
               for console applications.  This is the default behaviour for Cygwin
               and MinGW targets.
    
           -mcygwin
               This option is available for Cygwin targets.  It specifies that the
               Cygwin internal interface is to be used for predefined preprocessor
               macros, C runtime libraries and related linker paths and options.
               For Cygwin targets this is the default behaviour.  This option is
               deprecated and will be removed in a future release.
    
           -mno-cygwin
               This option is available for Cygwin targets.  It specifies that the
               MinGW internal interface is to be used instead of Cygwin's, by
               setting MinGW-related predefined macros and linker paths and
               default library options.  This option is deprecated and will be
               removed in a future release.
    
           -mdll
               This option is available for Cygwin and MinGW targets.  It
               specifies that a DLL - a dynamic link library - is to be generated,
               enabling the selection of the required runtime startup object and
               library/startup code.
    
           -mwindows
               This option is available for Cygwin and MinGW targets.  It
               specifies that a GUI application is to be generated by instructing
               the linker to set the PE header subsystem type appropriately.
    
           See also under i386 and x86-64 Options for standard options.
    
       IA-64 Options
           These are the -m options defined for the Intel IA-64 architecture.
    
           -mbig-endian
               Generate code for a big endian target.  This is the default for HP-
               UX.
    
           -mlittle-endian
               Generate code for a little endian target.  This is the default for
               AIX5 and GNU/Linux.
    
           -mgnu-as
           -mno-gnu-as
               Generate (or don't) code for the GNU assembler.  This is the
               default.
    
           -mgnu-ld
           -mno-gnu-ld
               Generate (or don't) code for the GNU linker.  This is the default.
    
           -mno-pic
               Generate code that does not use a global pointer register.  The
               result is not position independent code, and violates the IA-64
               ABI.
    
           -mvolatile-asm-stop
           -mno-volatile-asm-stop
               Generate (or don't) a stop bit immediately before and after
               volatile asm statements.
    
           -mregister-names
           -mno-register-names
               Generate (or don't) in, loc, and out register names for the stacked
               registers.  This may make assembler output more readable.
    
           -mno-sdata
           -msdata
               Disable (or enable) optimizations that use the small data section.
               This may be useful for working around optimizer bugs.
    
           -mconstant-gp
               Generate code that uses a single constant global pointer value.
               This is useful when compiling kernel code.
               Generate code for inline divides of integer values using the
               minimum latency algorithm.
    
           -minline-int-divide-max-throughput
               Generate code for inline divides of integer values using the
               maximum throughput algorithm.
    
           -minline-sqrt-min-latency
               Generate code for inline square roots using the minimum latency
               algorithm.
    
           -minline-sqrt-max-throughput
               Generate code for inline square roots using the maximum throughput
               algorithm.
    
           -mno-dwarf2-asm
           -mdwarf2-asm
               Don't (or do) generate assembler code for the DWARF2 line number
               debugging info.  This may be useful when not using the GNU
               assembler.
    
           -mearly-stop-bits
           -mno-early-stop-bits
               Allow stop bits to be placed earlier than immediately preceding the
               instruction that triggered the stop bit.  This can improve
               instruction scheduling, but does not always do so.
    
           -mfixed-range=register-range
               Generate code treating the given register range as fixed registers.
               A fixed register is one that the register allocator can not use.
               This is useful when compiling kernel code.  A register range is
               specified as two registers separated by a dash.  Multiple register
               ranges can be specified separated by a comma.
    
           -mtls-size=tls-size
               Specify bit size of immediate TLS offsets.  Valid values are 14,
               22, and 64.
    
           -mtune=cpu-type
               Tune the instruction scheduling for a particular CPU, Valid values
               are itanium, itanium1, merced, itanium2, and mckinley.
    
           -mt
           -pthread
               Add support for multithreading using the POSIX threads library.
               This option sets flags for both the preprocessor and linker.  It
               does not affect the thread safety of object code produced by the
               compiler or that of libraries supplied with it.  These are HP-UX
               specific flags.
    
           -milp32
           -mlp64
               result in generation of the ld.a instructions and the corresponding
               check instructions (ld.c / chk.a).  The default is 'enable'.
    
           -mno-sched-control-spec
           -msched-control-spec
               (Dis/En)able control speculative scheduling.  This feature is
               available only during region scheduling (i.e. before reload).  This
               will result in generation of the ld.s instructions and the
               corresponding check instructions chk.s .  The default is 'disable'.
    
           -msched-br-in-data-spec
           -mno-sched-br-in-data-spec
               (En/Dis)able speculative scheduling of the instructions that are
               dependent on the data speculative loads before reload.  This is
               effective only with -msched-br-data-spec enabled.  The default is
               'enable'.
    
           -msched-ar-in-data-spec
           -mno-sched-ar-in-data-spec
               (En/Dis)able speculative scheduling of the instructions that are
               dependent on the data speculative loads after reload.  This is
               effective only with -msched-ar-data-spec enabled.  The default is
               'enable'.
    
           -msched-in-control-spec
           -mno-sched-in-control-spec
               (En/Dis)able speculative scheduling of the instructions that are
               dependent on the control speculative loads.  This is effective only
               with -msched-control-spec enabled.  The default is 'enable'.
    
           -msched-ldc
           -mno-sched-ldc
               (En/Dis)able use of simple data speculation checks ld.c .  If
               disabled, only chk.a instructions will be emitted to check data
               speculative loads.  The default is 'enable'.
    
           -mno-sched-control-ldc
           -msched-control-ldc
               (Dis/En)able use of ld.c instructions to check control speculative
               loads.  If enabled, in case of control speculative load with no
               speculatively scheduled dependent instructions this load will be
               emitted as ld.sa and ld.c will be used to check it.  The default is
               'disable'.
    
           -mno-sched-spec-verbose
           -msched-spec-verbose
               (Dis/En)able printing of the information about speculative motions.
    
           -mno-sched-prefer-non-data-spec-insns
           -msched-prefer-non-data-spec-insns
               If enabled, data speculative instructions will be chosen for
               schedule only if there are no other choices at the moment.  This
               of the speculation a bit more conservative.  The default is
               'disable'.
    
       M32C Options
           -mcpu=name
               Select the CPU for which code is generated.  name may be one of r8c
               for the R8C/Tiny series, m16c for the M16C (up to /60) series,
               m32cm for the M16C/80 series, or m32c for the M32C/80 series.
    
           -msim
               Specifies that the program will be run on the simulator.  This
               causes an alternate runtime library to be linked in which supports,
               for example, file I/O.  You must not use this option when
               generating programs that will run on real hardware; you must
               provide your own runtime library for whatever I/O functions are
               needed.
    
           -memregs=number
               Specifies the number of memory-based pseudo-registers GCC will use
               during code generation.  These pseudo-registers will be used like
               real registers, so there is a tradeoff between GCC's ability to fit
               the code into available registers, and the performance penalty of
               using memory instead of registers.  Note that all modules in a
               program must be compiled with the same value for this option.
               Because of that, you must not use this option with the default
               runtime libraries gcc builds.
    
       M32R/D Options
           These -m options are defined for Renesas M32R/D architectures:
    
           -m32r2
               Generate code for the M32R/2.
    
           -m32rx
               Generate code for the M32R/X.
    
           -m32r
               Generate code for the M32R.  This is the default.
    
           -mmodel=small
               Assume all objects live in the lower 16MB of memory (so that their
               addresses can be loaded with the "ld24" instruction), and assume
               all subroutines are reachable with the "bl" instruction.  This is
               the default.
    
               The addressability of a particular object can be set with the
               "model" attribute.
    
           -mmodel=medium
               Assume objects may be anywhere in the 32-bit address space (the
               compiler will generate "seth/add3" instructions to load their
               addresses), and assume all subroutines are reachable with the "bl"
               The small data area consists of sections .sdata and .sbss.  Objects
               may be explicitly put in the small data area with the "section"
               attribute using one of these sections.
    
           -msdata=sdata
               Put small global and static data in the small data area, but do not
               generate special code to reference them.
    
           -msdata=use
               Put small global and static data in the small data area, and
               generate special instructions to reference them.
    
           -G num
               Put global and static objects less than or equal to num bytes into
               the small data or bss sections instead of the normal data or bss
               sections.  The default value of num is 8.  The -msdata option must
               be set to one of sdata or use for this option to have any effect.
    
               All modules should be compiled with the same -G num value.
               Compiling with different values of num may or may not work; if it
               doesn't the linker will give an error message---incorrect code will
               not be generated.
    
           -mdebug
               Makes the M32R specific code in the compiler display some
               statistics that might help in debugging programs.
    
           -malign-loops
               Align all loops to a 32-byte boundary.
    
           -mno-align-loops
               Do not enforce a 32-byte alignment for loops.  This is the default.
    
           -missue-rate=number
               Issue number instructions per cycle.  number can only be 1 or 2.
    
           -mbranch-cost=number
               number can only be 1 or 2.  If it is 1 then branches will be
               preferred over conditional code, if it is 2, then the opposite will
               apply.
    
           -mflush-trap=number
               Specifies the trap number to use to flush the cache.  The default
               is 12.  Valid numbers are between 0 and 15 inclusive.
    
           -mno-flush-trap
               Specifies that the cache cannot be flushed by using a trap.
    
           -mflush-func=name
               Specifies the name of the operating system function to call to
               flush the cache.  The default is _flush_cache, but a function call
               will only be used if a trap is not available.
               architectures are selected according to Freescale's ISA
               classification and the permissible values are: isaa, isaaplus, isab
               and isac.
    
               gcc defines a macro __mcfarch__ whenever it is generating code for
               a ColdFire target.  The arch in this macro is one of the -march
               arguments given above.
    
               When used together, -march and -mtune select code that runs on a
               family of similar processors but that is optimized for a particular
               microarchitecture.
    
           -mcpu=cpu
               Generate code for a specific M680x0 or ColdFire processor.  The
               M680x0 cpus are: 68000, 68010, 68020, 68030, 68040, 68060, 68302,
               68332 and cpu32.  The ColdFire cpus are given by the table below,
               which also classifies the CPUs into families:
    
               Family : -mcpu arguments
               51qe : 51qe
               5206 : 5202 5204 5206
               5206e : 5206e
               5208 : 5207 5208
               5211a : 5210a 5211a
               5213 : 5211 5212 5213
               5216 : 5214 5216
               52235 : 52230 52231 52232 52233 52234 52235
               5225 : 5224 5225
               5235 : 5232 5233 5234 5235 523x
               5249 : 5249
               5250 : 5250
               5271 : 5270 5271
               5272 : 5272
               5275 : 5274 5275
               5282 : 5280 5281 5282 528x
               5307 : 5307
               5329 : 5327 5328 5329 532x
               5373 : 5372 5373 537x
               5407 : 5407
               5475 : 5470 5471 5472 5473 5474 5475 547x 5480 5481 5482 5483 5484
               5485
    
               -mcpu=cpu overrides -march=arch if arch is compatible with cpu.
               Other combinations of -mcpu and -march are rejected.
    
               gcc defines the macro __mcf_cpu_cpu when ColdFire target cpu is
               selected.  It also defines __mcf_family_family, where the value of
               family is given by the table above.
    
           -mtune=tune
               Tune the code for a particular microarchitecture, within the
               constraints set by -march and -mcpu.  The M680x0 microarchitectures
               the range.
    
               gcc also defines the macro __muarch__ when tuning for ColdFire
               microarchitecture uarch, where uarch is one of the arguments given
               above.
    
           -m68000
           -mc68000
               Generate output for a 68000.  This is the default when the compiler
               is configured for 68000-based systems.  It is equivalent to
               -march=68000.
    
               Use this option for microcontrollers with a 68000 or EC000 core,
               including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356.
    
           -m68010
               Generate output for a 68010.  This is the default when the compiler
               is configured for 68010-based systems.  It is equivalent to
               -march=68010.
    
           -m68020
           -mc68020
               Generate output for a 68020.  This is the default when the compiler
               is configured for 68020-based systems.  It is equivalent to
               -march=68020.
    
           -m68030
               Generate output for a 68030.  This is the default when the compiler
               is configured for 68030-based systems.  It is equivalent to
               -march=68030.
    
           -m68040
               Generate output for a 68040.  This is the default when the compiler
               is configured for 68040-based systems.  It is equivalent to
               -march=68040.
    
               This option inhibits the use of 68881/68882 instructions that have
               to be emulated by software on the 68040.  Use this option if your
               68040 does not have code to emulate those instructions.
    
           -m68060
               Generate output for a 68060.  This is the default when the compiler
               is configured for 68060-based systems.  It is equivalent to
               -march=68060.
    
               This option inhibits the use of 68020 and 68881/68882 instructions
               that have to be emulated by software on the 68060.  Use this option
               if your 68060 does not have code to emulate those instructions.
    
           -mcpu32
               Generate output for a CPU32.  This is the default when the compiler
               is configured for CPU32-based systems.  It is equivalent to
    
           -m5206e
               Generate output for a 5206e ColdFire CPU.  The option is now
               deprecated in favor of the equivalent -mcpu=5206e.
    
           -m528x
               Generate output for a member of the ColdFire 528X family.  The
               option is now deprecated in favor of the equivalent -mcpu=528x.
    
           -m5307
               Generate output for a ColdFire 5307 CPU.  The option is now
               deprecated in favor of the equivalent -mcpu=5307.
    
           -m5407
               Generate output for a ColdFire 5407 CPU.  The option is now
               deprecated in favor of the equivalent -mcpu=5407.
    
           -mcfv4e
               Generate output for a ColdFire V4e family CPU (e.g. 547x/548x).
               This includes use of hardware floating point instructions.  The
               option is equivalent to -mcpu=547x, and is now deprecated in favor
               of that option.
    
           -m68020-40
               Generate output for a 68040, without using any of the new
               instructions.  This results in code which can run relatively
               efficiently on either a 68020/68881 or a 68030 or a 68040.  The
               generated code does use the 68881 instructions that are emulated on
               the 68040.
    
               The option is equivalent to -march=68020 -mtune=68020-40.
    
           -m68020-60
               Generate output for a 68060, without using any of the new
               instructions.  This results in code which can run relatively
               efficiently on either a 68020/68881 or a 68030 or a 68040.  The
               generated code does use the 68881 instructions that are emulated on
               the 68060.
    
               The option is equivalent to -march=68020 -mtune=68020-60.
    
           -mhard-float
           -m68881
               Generate floating-point instructions.  This is the default for
               68020 and above, and for ColdFire devices that have an FPU.  It
               defines the macro __HAVE_68881__ on M680x0 targets and __mcffpu__
               on ColdFire targets.
    
           -msoft-float
               Do not generate floating-point instructions; use library calls
               instead.  This is the default for 68000, 68010, and 68832 targets.
               It is also the default for ColdFire devices that have no FPU.
               Additionally, parameters passed on the stack are also aligned to a
               16-bit boundary even on targets whose API mandates promotion to
               32-bit.
    
           -mno-short
               Do not consider type "int" to be 16 bits wide.  This is the
               default.
    
           -mnobitfield
           -mno-bitfield
               Do not use the bit-field instructions.  The -m68000, -mcpu32 and
               -m5200 options imply -mnobitfield.
    
           -mbitfield
               Do use the bit-field instructions.  The -m68020 option implies
               -mbitfield.  This is the default if you use a configuration
               designed for a 68020.
    
           -mrtd
               Use a different function-calling convention, in which functions
               that take a fixed number of arguments return with the "rtd"
               instruction, which pops their arguments while returning.  This
               saves one instruction in the caller since there is no need to pop
               the arguments there.
    
               This calling convention is incompatible with the one normally used
               on Unix, so you cannot use it if you need to call libraries
               compiled with the Unix compiler.
    
               Also, you must provide function prototypes for all functions that
               take variable numbers of arguments (including "printf"); otherwise
               incorrect code will be generated for calls to those functions.
    
               In addition, seriously incorrect code will result if you call a
               function with too many arguments.  (Normally, extra arguments are
               harmlessly ignored.)
    
               The "rtd" instruction is supported by the 68010, 68020, 68030,
               68040, 68060 and CPU32 processors, but not by the 68000 or 5200.
    
           -mno-rtd
               Do not use the calling conventions selected by -mrtd.  This is the
               default.
    
           -malign-int
           -mno-align-int
               Control whether GCC aligns "int", "long", "long long", "float",
               "double", and "long double" variables on a 32-bit boundary
               (-malign-int) or a 16-bit boundary (-mno-align-int).  Aligning
               variables on 32-bit boundaries produces code that runs somewhat
               faster on processors with 32-bit busses at the expense of more
               memory.
               Do not (do) assume that unaligned memory references will be handled
               by the system.
    
           -msep-data
               Generate code that allows the data segment to be located in a
               different area of memory from the text segment.  This allows for
               execute in place in an environment without virtual memory
               management.  This option implies -fPIC.
    
           -mno-sep-data
               Generate code that assumes that the data segment follows the text
               segment.  This is the default.
    
           -mid-shared-library
               Generate code that supports shared libraries via the library ID
               method.  This allows for execute in place and shared libraries in
               an environment without virtual memory management.  This option
               implies -fPIC.
    
           -mno-id-shared-library
               Generate code that doesn't assume ID based shared libraries are
               being used.  This is the default.
    
           -mshared-library-id=n
               Specified the identification number of the ID based shared library
               being compiled.  Specifying a value of 0 will generate more compact
               code, specifying other values will force the allocation of that
               number to the current library but is no more space or time
               efficient than omitting this option.
    
           -mxgot
           -mno-xgot
               When generating position-independent code for ColdFire, generate
               code that works if the GOT has more than 8192 entries.  This code
               is larger and slower than code generated without this option.  On
               M680x0 processors, this option is not needed; -fPIC suffices.
    
               GCC normally uses a single instruction to load values from the GOT.
               While this is relatively efficient, it only works if the GOT is
               smaller than about 64k.  Anything larger causes the linker to
               report an error such as:
    
                       relocation truncated to fit: R_68K_GOT16O foobar
    
               If this happens, you should recompile your code with -mxgot.  It
               should then work with very large GOTs.  However, code generated
               with -mxgot is less efficient, since it takes 4 instructions to
               fetch the value of a global symbol.
    
               Note that some linkers, including newer versions of the GNU linker,
               can create multiple GOTs and sort GOT entries.  If you have such a
               linker, you should only need to use -mxgot when compiling a single
               compiler is configured for 68HC11-based systems.
    
           -m6812
           -m68hc12
               Generate output for a 68HC12.  This is the default when the
               compiler is configured for 68HC12-based systems.
    
           -m68S12
           -m68hcs12
               Generate output for a 68HCS12.
    
           -mauto-incdec
               Enable the use of 68HC12 pre and post auto-increment and auto-
               decrement addressing modes.
    
           -minmax
           -nominmax
               Enable the use of 68HC12 min and max instructions.
    
           -mlong-calls
           -mno-long-calls
               Treat all calls as being far away (near).  If calls are assumed to
               be far away, the compiler will use the "call" instruction to call a
               function and the "rtc" instruction for returning.
    
           -mshort
               Consider type "int" to be 16 bits wide, like "short int".
    
           -msoft-reg-count=count
               Specify the number of pseudo-soft registers which are used for the
               code generation.  The maximum number is 32.  Using more pseudo-soft
               register may or may not result in better code depending on the
               program.  The default is 4 for 68HC11 and 2 for 68HC12.
    
       MCore Options
           These are the -m options defined for the Motorola M*Core processors.
    
           -mhardlit
           -mno-hardlit
               Inline constants into the code stream if it can be done in two
               instructions or less.
    
           -mdiv
           -mno-div
               Use the divide instruction.  (Enabled by default).
    
           -mrelax-immediate
           -mno-relax-immediate
               Allow arbitrary sized immediates in bit operations.
    
           -mwide-bitfields
           -mno-wide-bitfields
           -mlittle-endian
           -mbig-endian
               Generate code for a little endian target.
    
           -m210
           -m340
               Generate code for the 210 processor.
    
           -mno-lsim
               Assume that run-time support has been provided and so omit the
               simulator library (libsim.a) from the linker command line.
    
           -mstack-increment=size
               Set the maximum amount for a single stack increment operation.
               Large values can increase the speed of programs which contain
               functions that need a large amount of stack space, but they can
               also trigger a segmentation fault if the stack is extended too
               much.  The default value is 0x1000.
    
       MIPS Options
           -EB Generate big-endian code.
    
           -EL Generate little-endian code.  This is the default for mips*el-*-*
               configurations.
    
           -march=arch
               Generate code that will run on arch, which can be the name of a
               generic MIPS ISA, or the name of a particular processor.  The ISA
               names are: mips1, mips2, mips3, mips4, mips32, mips32r2, mips64 and
               mips64r2.  The processor names are: 4kc, 4km, 4kp, 4ksc, 4kec,
               4kem, 4kep, 4ksd, 5kc, 5kf, 20kc, 24kc, 24kf2_1, 24kf1_1, 24kec,
               24kef2_1, 24kef1_1, 34kc, 34kf2_1, 34kf1_1, 74kc, 74kf2_1, 74kf1_1,
               74kf3_2, loongson2e, loongson2f, m4k, octeon, orion, r2000, r3000,
               r3900, r4000, r4400, r4600, r4650, r6000, r8000, rm7000, rm9000,
               r10000, r12000, r14000, r16000, sb1, sr71000, vr4100, vr4111,
               vr4120, vr4130, vr4300, vr5000, vr5400, vr5500 and xlr.  The
               special value from-abi selects the most compatible architecture for
               the selected ABI (that is, mips1 for 32-bit ABIs and mips3 for
               64-bit ABIs).
    
               Native Linux/GNU toolchains also support the value native, which
               selects the best architecture option for the host processor.
               -march=native has no effect if GCC does not recognize the
               processor.
    
               In processor names, a final 000 can be abbreviated as k (for
               example, -march=r2k).  Prefixes are optional, and vr may be written
               r.
    
               Names of the form nf2_1 refer to processors with FPUs clocked at
               half the rate of the core, names of the form nf1_1 refer to
               processors with FPUs clocked at the same rate as the core, and
               abbreviate 000 as k.  In the case of from-abi, the macro names the
               resolved architecture (either "mips1" or "mips3").  It names the
               default architecture when no -march option is given.
    
           -mtune=arch
               Optimize for arch.  Among other things, this option controls the
               way instructions are scheduled, and the perceived cost of
               arithmetic operations.  The list of arch values is the same as for
               -march.
    
               When this option is not used, GCC will optimize for the processor
               specified by -march.  By using -march and -mtune together, it is
               possible to generate code that will run on a family of processors,
               but optimize the code for one particular member of that family.
    
               -mtune defines the macros _MIPS_TUNE and _MIPS_TUNE_foo, which work
               in the same way as the -march ones described above.
    
           -mips1
               Equivalent to -march=mips1.
    
           -mips2
               Equivalent to -march=mips2.
    
           -mips3
               Equivalent to -march=mips3.
    
           -mips4
               Equivalent to -march=mips4.
    
           -mips32
               Equivalent to -march=mips32.
    
           -mips32r2
               Equivalent to -march=mips32r2.
    
           -mips64
               Equivalent to -march=mips64.
    
           -mips64r2
               Equivalent to -march=mips64r2.
    
           -mips16
           -mno-mips16
               Generate (do not generate) MIPS16 code.  If GCC is targetting a
               MIPS32 or MIPS64 architecture, it will make use of the MIPS16e ASE.
    
               MIPS16 code generation can also be controlled on a per-function
               basis by means of "mips16" and "nomips16" attributes.
    
           -mflip-mips16
               Generate MIPS16 code on alternating functions.  This option is
    
           -mabi=32
           -mabi=o64
           -mabi=n32
           -mabi=64
           -mabi=eabi
               Generate code for the given ABI.
    
               Note that the EABI has a 32-bit and a 64-bit variant.  GCC normally
               generates 64-bit code when you select a 64-bit architecture, but
               you can use -mgp32 to get 32-bit code instead.
    
               For information about the O64 ABI, see
               <http://gcc.gnu.org/projects/mipso64-abi.html>.
    
               GCC supports a variant of the o32 ABI in which floating-point
               registers are 64 rather than 32 bits wide.  You can select this
               combination with -mabi=32 -mfp64.  This ABI relies on the mthc1 and
               mfhc1 instructions and is therefore only supported for MIPS32R2
               processors.
    
               The register assignments for arguments and return values remain the
               same, but each scalar value is passed in a single 64-bit register
               rather than a pair of 32-bit registers.  For example, scalar
               floating-point values are returned in $f0 only, not a $f0/$f1 pair.
               The set of call-saved registers also remains the same, but all 64
               bits are saved.
    
           -mabicalls
           -mno-abicalls
               Generate (do not generate) code that is suitable for SVR4-style
               dynamic objects.  -mabicalls is the default for SVR4-based systems.
    
           -mshared
           -mno-shared
               Generate (do not generate) code that is fully position-independent,
               and that can therefore be linked into shared libraries.  This
               option only affects -mabicalls.
    
               All -mabicalls code has traditionally been position-independent,
               regardless of options like -fPIC and -fpic.  However, as an
               extension, the GNU toolchain allows executables to use absolute
               accesses for locally-binding symbols.  It can also use shorter GP
               initialization sequences and generate direct calls to locally-
               defined functions.  This mode is selected by -mno-shared.
    
               -mno-shared depends on binutils 2.16 or higher and generates
               objects that can only be linked by the GNU linker.  However, the
               option does not affect the ABI of the final executable; it only
               affects the ABI of relocatable objects.  Using -mno-shared will
               generally make executables both smaller and quicker.
    
               -mshared is the default.
               offset table.
    
               GCC normally uses a single instruction to load values from the GOT.
               While this is relatively efficient, it will only work if the GOT is
               smaller than about 64k.  Anything larger will cause the linker to
               report an error such as:
    
                       relocation truncated to fit: R_MIPS_GOT16 foobar
    
               If this happens, you should recompile your code with -mxgot.  It
               should then work with very large GOTs, although it will also be
               less efficient, since it will take three instructions to fetch the
               value of a global symbol.
    
               Note that some linkers can create multiple GOTs.  If you have such
               a linker, you should only need to use -mxgot when a single object
               file accesses more than 64k's worth of GOT entries.  Very few do.
    
               These options have no effect unless GCC is generating position
               independent code.
    
           -mgp32
               Assume that general-purpose registers are 32 bits wide.
    
           -mgp64
               Assume that general-purpose registers are 64 bits wide.
    
           -mfp32
               Assume that floating-point registers are 32 bits wide.
    
           -mfp64
               Assume that floating-point registers are 64 bits wide.
    
           -mhard-float
               Use floating-point coprocessor instructions.
    
           -msoft-float
               Do not use floating-point coprocessor instructions.  Implement
               floating-point calculations using library calls instead.
    
           -msingle-float
               Assume that the floating-point coprocessor only supports single-
               precision operations.
    
           -mdouble-float
               Assume that the floating-point coprocessor supports double-
               precision operations.  This is the default.
    
           -mllsc
           -mno-llsc
               Use (do not use) ll, sc, and sync instructions to implement atomic
               memory built-in functions.  When neither option is specified, GCC
    
           -mdspr2
           -mno-dspr2
               Use (do not use) revision 2 of the MIPS DSP ASE.
                 This option defines the preprocessor macros __mips_dsp and
               __mips_dspr2.  It also defines __mips_dsp_rev to 2.
    
           -msmartmips
           -mno-smartmips
               Use (do not use) the MIPS SmartMIPS ASE.
    
           -mpaired-single
           -mno-paired-single
               Use (do not use) paired-single floating-point instructions.
                 This option requires hardware floating-point support to be
               enabled.
    
           -mdmx
           -mno-mdmx
               Use (do not use) MIPS Digital Media Extension instructions.  This
               option can only be used when generating 64-bit code and requires
               hardware floating-point support to be enabled.
    
           -mips3d
           -mno-mips3d
               Use (do not use) the MIPS-3D ASE.  The option -mips3d implies
               -mpaired-single.
    
           -mmt
           -mno-mt
               Use (do not use) MT Multithreading instructions.
    
           -mlong64
               Force "long" types to be 64 bits wide.  See -mlong32 for an
               explanation of the default and the way that the pointer size is
               determined.
    
           -mlong32
               Force "long", "int", and pointer types to be 32 bits wide.
    
               The default size of "int"s, "long"s and pointers depends on the
               ABI.  All the supported ABIs use 32-bit "int"s.  The n64 ABI uses
               64-bit "long"s, as does the 64-bit EABI; the others use 32-bit
               "long"s.  Pointers are the same size as "long"s, or the same size
               as integer registers, whichever is smaller.
    
           -msym32
           -mno-sym32
               Assume (do not assume) that all symbols have 32-bit values,
               regardless of the selected ABI.  This option is useful in
               combination with -mabi=64 and -mno-abicalls because it allows GCC
               to generate shorter and faster references to symbolic addresses.
               If the linker complains that an application is using too much small
               data, you might want to try rebuilding the less performance-
               critical parts with -mno-local-sdata.  You might also want to build
               large libraries with -mno-local-sdata, so that the libraries leave
               more room for the main program.
    
           -mextern-sdata
           -mno-extern-sdata
               Assume (do not assume) that externally-defined data will be in a
               small data section if that data is within the -G limit.
               -mextern-sdata is the default for all configurations.
    
               If you compile a module Mod with -mextern-sdata -G num -mgpopt, and
               Mod references a variable Var that is no bigger than num bytes, you
               must make sure that Var is placed in a small data section.  If Var
               is defined by another module, you must either compile that module
               with a high-enough -G setting or attach a "section" attribute to
               Var's definition.  If Var is common, you must link the application
               with a high-enough -G setting.
    
               The easiest way of satisfying these restrictions is to compile and
               link every module with the same -G option.  However, you may wish
               to build a library that supports several different small data
               limits.  You can do this by compiling the library with the highest
               supported -G setting and additionally using -mno-extern-sdata to
               stop the library from making assumptions about externally-defined
               data.
    
           -mgpopt
           -mno-gpopt
               Use (do not use) GP-relative accesses for symbols that are known to
               be in a small data section; see -G, -mlocal-sdata and
               -mextern-sdata.  -mgpopt is the default for all configurations.
    
               -mno-gpopt is useful for cases where the $gp register might not
               hold the value of "_gp".  For example, if the code is part of a
               library that might be used in a boot monitor, programs that call
               boot monitor routines will pass an unknown value in $gp.  (In such
               situations, the boot monitor itself would usually be compiled with
               -G0.)
    
               -mno-gpopt implies -mno-local-sdata and -mno-extern-sdata.
    
           -membedded-data
           -mno-embedded-data
               Allocate variables to the read-only data section first if possible,
               then next in the small data section if possible, otherwise in data.
               This gives slightly slower code than the default, but reduces the
               amount of RAM required when executing, and thus may be preferred
               for some embedded systems.
    
           -muninit-const-in-rodata
                   sections, but other instructions must not do so.  This option
                   is useful on 4KSc and 4KSd processors when the code TLBs have
                   the Read Inhibit bit set.  It is also useful on processors that
                   can be configured to have a dual instruction/data SRAM
                   interface and that, like the M4K, automatically redirect PC-
                   relative loads to the instruction RAM.
    
               -mcode-readable=no
                   Instructions must not access executable sections.  This option
                   can be useful on targets that are configured to have a dual
                   instruction/data SRAM interface but that (unlike the M4K) do
                   not automatically redirect PC-relative loads to the instruction
                   RAM.
    
           -msplit-addresses
           -mno-split-addresses
               Enable (disable) use of the "%hi()" and "%lo()" assembler
               relocation operators.  This option has been superseded by
               -mexplicit-relocs but is retained for backwards compatibility.
    
           -mexplicit-relocs
           -mno-explicit-relocs
               Use (do not use) assembler relocation operators when dealing with
               symbolic addresses.  The alternative, selected by
               -mno-explicit-relocs, is to use assembler macros instead.
    
               -mexplicit-relocs is the default if GCC was configured to use an
               assembler that supports relocation operators.
    
           -mcheck-zero-division
           -mno-check-zero-division
               Trap (do not trap) on integer division by zero.
    
               The default is -mcheck-zero-division.
    
           -mdivide-traps
           -mdivide-breaks
               MIPS systems check for division by zero by generating either a
               conditional trap or a break instruction.  Using traps results in
               smaller code, but is only supported on MIPS II and later.  Also,
               some versions of the Linux kernel have a bug that prevents trap
               from generating the proper signal ("SIGFPE").  Use -mdivide-traps
               to allow conditional traps on architectures that support them and
               -mdivide-breaks to force the use of breaks.
    
               The default is usually -mdivide-traps, but this can be overridden
               at configure time using --with-divide=breaks.  Divide-by-zero
               checks can be completely disabled using -mno-check-zero-division.
    
           -mmemcpy
           -mno-memcpy
               Force (do not force) the use of "memcpy()" for non-trivial block
               Enable (disable) use of the "mad", "madu" and "mul" instructions,
               as provided by the R4650 ISA.
    
           -mfused-madd
           -mno-fused-madd
               Enable (disable) use of the floating point multiply-accumulate
               instructions, when they are available.  The default is
               -mfused-madd.
    
               When multiply-accumulate instructions are used, the intermediate
               product is calculated to infinite precision and is not subject to
               the FCSR Flush to Zero bit.  This may be undesirable in some
               circumstances.
    
           -nocpp
               Tell the MIPS assembler to not run its preprocessor over user
               assembler files (with a .s suffix) when assembling them.
    
           -mfix-r4000
           -mno-fix-r4000
               Work around certain R4000 CPU errata:
    
               -   A double-word or a variable shift may give an incorrect result
                   if executed immediately after starting an integer division.
    
               -   A double-word or a variable shift may give an incorrect result
                   if executed while an integer multiplication is in progress.
    
               -   An integer division may give an incorrect result if started in
                   a delay slot of a taken branch or a jump.
    
           -mfix-r4400
           -mno-fix-r4400
               Work around certain R4400 CPU errata:
    
               -   A double-word or a variable shift may give an incorrect result
                   if executed immediately after starting an integer division.
    
           -mfix-r10000
           -mno-fix-r10000
               Work around certain R10000 errata:
    
               -   "ll"/"sc" sequences may not behave atomically on revisions
                   prior to 3.0.  They may deadlock on revisions 2.6 and earlier.
    
               This option can only be used if the target architecture supports
               branch-likely instructions.  -mfix-r10000 is the default when
               -march=r10000 is used; -mno-fix-r10000 is the default otherwise.
    
           -mfix-vr4120
           -mno-fix-vr4120
               Work around certain VR4120 errata:
    
           -mfix-vr4130
               Work around the VR4130 "mflo"/"mfhi" errata.  The workarounds are
               implemented by the assembler rather than by GCC, although GCC will
               avoid using "mflo" and "mfhi" if the VR4130 "macc", "macchi",
               "dmacc" and "dmacchi" instructions are available instead.
    
           -mfix-sb1
           -mno-fix-sb1
               Work around certain SB-1 CPU core errata.  (This flag currently
               works around the SB-1 revision 2 "F1" and "F2" floating point
               errata.)
    
           -mr10k-cache-barrier=setting
               Specify whether GCC should insert cache barriers to avoid the side-
               effects of speculation on R10K processors.
    
               In common with many processors, the R10K tries to predict the
               outcome of a conditional branch and speculatively executes
               instructions from the "taken" branch.  It later aborts these
               instructions if the predicted outcome was wrong.  However, on the
               R10K, even aborted instructions can have side effects.
    
               This problem only affects kernel stores and, depending on the
               system, kernel loads.  As an example, a speculatively-executed
               store may load the target memory into cache and mark the cache line
               as dirty, even if the store itself is later aborted.  If a DMA
               operation writes to the same area of memory before the "dirty" line
               is flushed, the cached data will overwrite the DMA-ed data.  See
               the R10K processor manual for a full description, including other
               potential problems.
    
               One workaround is to insert cache barrier instructions before every
               memory access that might be speculatively executed and that might
               have side effects even if aborted.  -mr10k-cache-barrier=setting
               controls GCC's implementation of this workaround.  It assumes that
               aborted accesses to any byte in the following regions will not have
               side effects:
    
               1.  the memory occupied by the current function's stack frame;
    
               2.  the memory occupied by an incoming stack argument;
    
               3.  the memory occupied by an object with a link-time-constant
                   address.
    
               It is the kernel's responsibility to ensure that speculative
               accesses to these regions are indeed safe.
    
               If the input program contains a function declaration such as:
    
                       void foo (void);
    
                   speculatively executed and that might have side effects even if
                   aborted.
    
               -mr10k-cache-barrier=none
                   Disable the insertion of cache barriers.  This is the default
                   setting.
    
           -mflush-func=func
           -mno-flush-func
               Specifies the function to call to flush the I and D caches, or to
               not call any such function.  If called, the function must take the
               same arguments as the common "_flush_func()", that is, the address
               of the memory range for which the cache is being flushed, the size
               of the memory range, and the number 3 (to flush both caches).  The
               default depends on the target GCC was configured for, but commonly
               is either _flush_func or __cpu_flush.
    
           mbranch-cost=num
               Set the cost of branches to roughly num "simple" instructions.
               This cost is only a heuristic and is not guaranteed to produce
               consistent results across releases.  A zero cost redundantly
               selects the default, which is based on the -mtune setting.
    
           -mbranch-likely
           -mno-branch-likely
               Enable or disable use of Branch Likely instructions, regardless of
               the default for the selected architecture.  By default, Branch
               Likely instructions may be generated if they are supported by the
               selected architecture.  An exception is for the MIPS32 and MIPS64
               architectures and processors which implement those architectures;
               for those, Branch Likely instructions will not be generated by
               default because the MIPS32 and MIPS64 architectures specifically
               deprecate their use.
    
           -mfp-exceptions
           -mno-fp-exceptions
               Specifies whether FP exceptions are enabled.  This affects how we
               schedule FP instructions for some processors.  The default is that
               FP exceptions are enabled.
    
               For instance, on the SB-1, if FP exceptions are disabled, and we
               are emitting 64-bit code, then we can use both FP pipes.
               Otherwise, we can only use one FP pipe.
    
           -mvr4130-align
           -mno-vr4130-align
               The VR4130 pipeline is two-way superscalar, but can only issue two
               instructions together if the first one is 8-byte aligned.  When
               this option is enabled, GCC will align pairs of instructions that
               it thinks should execute in parallel.
    
               This option only has an effect when optimizing for the VR4130.  It
               respect to the "rE" epsilon register.
    
           -mabi=mmixware
           -mabi=gnu
               Generate code that passes function parameters and return values
               that (in the called function) are seen as registers $0 and up, as
               opposed to the GNU ABI which uses global registers $231 and up.
    
           -mzero-extend
           -mno-zero-extend
               When reading data from memory in sizes shorter than 64 bits, use
               (do not use) zero-extending load instructions by default, rather
               than sign-extending ones.
    
           -mknuthdiv
           -mno-knuthdiv
               Make the result of a division yielding a remainder have the same
               sign as the divisor.  With the default, -mno-knuthdiv, the sign of
               the remainder follows the sign of the dividend.  Both methods are
               arithmetically valid, the latter being almost exclusively used.
    
           -mtoplevel-symbols
           -mno-toplevel-symbols
               Prepend (do not prepend) a : to all global symbols, so the assembly
               code can be used with the "PREFIX" assembly directive.
    
           -melf
               Generate an executable in the ELF format, rather than the default
               mmo format used by the mmix simulator.
    
           -mbranch-predict
           -mno-branch-predict
               Use (do not use) the probable-branch instructions, when static
               branch prediction indicates a probable branch.
    
           -mbase-addresses
           -mno-base-addresses
               Generate (do not generate) code that uses base addresses.  Using a
               base address automatically generates a request (handled by the
               assembler and the linker) for a constant to be set up in a global
               register.  The register is used for one or more base address
               requests within the range 0 to 255 from the value held in the
               register.  The generally leads to short and fast code, but the
               number of different data items that can be addressed is limited.
               This means that a program that uses lots of static data may require
               -mno-base-addresses.
    
           -msingle-exit
           -mno-single-exit
               Force (do not force) generated code to have a single exit point in
               each function.
    
           -mno-am33
               Do not generate code which uses features specific to the AM33
               processor.  This is the default.
    
           -mreturn-pointer-on-d0
               When generating a function which returns a pointer, return the
               pointer in both "a0" and "d0".  Otherwise, the pointer is returned
               only in a0, and attempts to call such functions without a prototype
               would result in errors.  Note that this option is on by default;
               use -mno-return-pointer-on-d0 to disable it.
    
           -mno-crt0
               Do not link in the C run-time initialization object file.
    
           -mrelax
               Indicate to the linker that it should perform a relaxation
               optimization pass to shorten branches, calls and absolute memory
               addresses.  This option only has an effect when used on the command
               line for the final link step.
    
               This option makes symbolic debugging impossible.
    
       PDP-11 Options
           These options are defined for the PDP-11:
    
           -mfpu
               Use hardware FPP floating point.  This is the default.  (FIS
               floating point on the PDP-11/40 is not supported.)
    
           -msoft-float
               Do not use hardware floating point.
    
           -mac0
               Return floating-point results in ac0 (fr0 in Unix assembler
               syntax).
    
           -mno-ac0
               Return floating-point results in memory.  This is the default.
    
           -m40
               Generate code for a PDP-11/40.
    
           -m45
               Generate code for a PDP-11/45.  This is the default.
    
           -m10
               Generate code for a PDP-11/10.
    
           -mbcopy-builtin
               Use inline "movmemhi" patterns for copying memory.  This is the
               default.
    
    
           -mfloat32
           -mno-float64
               Use 32-bit "float".
    
           -mabshi
               Use "abshi2" pattern.  This is the default.
    
           -mno-abshi
               Do not use "abshi2" pattern.
    
           -mbranch-expensive
               Pretend that branches are expensive.  This is for experimenting
               with code generation only.
    
           -mbranch-cheap
               Do not pretend that branches are expensive.  This is the default.
    
           -msplit
               Generate code for a system with split I&D.
    
           -mno-split
               Generate code for a system without split I&D.  This is the default.
    
           -munix-asm
               Use Unix assembler syntax.  This is the default when configured for
               pdp11-*-bsd.
    
           -mdec-asm
               Use DEC assembler syntax.  This is the default when configured for
               any PDP-11 target other than pdp11-*-bsd.
    
       picoChip Options
           These -m options are defined for picoChip implementations:
    
           -mae=ae_type
               Set the instruction set, register set, and instruction scheduling
               parameters for array element type ae_type.  Supported values for
               ae_type are ANY, MUL, and MAC.
    
               -mae=ANY selects a completely generic AE type.  Code generated with
               this option will run on any of the other AE types.  The code will
               not be as efficient as it would be if compiled for a specific AE
               type, and some types of operation (e.g., multiplication) will not
               work properly on all types of AE.
    
               -mae=MUL selects a MUL AE type.  This is the most useful AE type
               for compiled code, and is the default.
    
               -mae=MAC selects a DSP-style MAC AE.  Code compiled with this
               option may suffer from poor performance of byte (char)
               manipulation, since the DSP AE does not provide hardware support
               AE has no hardware support for byte-level memory operations, so all
               byte load/stores must be synthesized from word load/store
               operations.  This is inefficient and a warning will be generated
               indicating to the programmer that they should rewrite the code to
               avoid byte operations, or to target an AE type which has the
               necessary hardware support.  This option enables the warning to be
               turned off.
    
       PowerPC Options
           These are listed under
    
       IBM RS/6000 and PowerPC Options
           These -m options are defined for the IBM RS/6000 and PowerPC:
    
           -mpower
           -mno-power
           -mpower2
           -mno-power2
           -mpowerpc
           -mno-powerpc
           -mpowerpc-gpopt
           -mno-powerpc-gpopt
           -mpowerpc-gfxopt
           -mno-powerpc-gfxopt
           -mpowerpc64
           -mno-powerpc64
           -mmfcrf
           -mno-mfcrf
           -mpopcntb
           -mno-popcntb
           -mpopcntd
           -mno-popcntd
           -mfprnd
           -mno-fprnd
           -mcmpb
           -mno-cmpb
           -mmfpgpr
           -mno-mfpgpr
           -mhard-dfp
           -mno-hard-dfp
               GCC supports two related instruction set architectures for the
               RS/6000 and PowerPC.  The POWER instruction set are those
               instructions supported by the rios chip set used in the original
               RS/6000 systems and the PowerPC instruction set is the architecture
               of the Freescale MPC5xx, MPC6xx, MPC8xx microprocessors, and the
               IBM 4xx, 6xx, and follow-on microprocessors.
    
               Neither architecture is a subset of the other.  However there is a
               large common subset of instructions supported by both.  An MQ
               register is included in processors supporting the POWER
               architecture.
    
               Specifying -mpowerpc-gpopt implies -mpowerpc and also allows GCC to
               use the optional PowerPC architecture instructions in the General
               Purpose group, including floating-point square root.  Specifying
               -mpowerpc-gfxopt implies -mpowerpc and also allows GCC to use the
               optional PowerPC architecture instructions in the Graphics group,
               including floating-point select.
    
               The -mmfcrf option allows GCC to generate the move from condition
               register field instruction implemented on the POWER4 processor and
               other processors that support the PowerPC V2.01 architecture.  The
               -mpopcntb option allows GCC to generate the popcount and double
               precision FP reciprocal estimate instruction implemented on the
               POWER5 processor and other processors that support the PowerPC
               V2.02 architecture.  The -mpopcntd option allows GCC to generate
               the popcount instruction implemented on the POWER7 processor and
               other processors that support the PowerPC V2.06 architecture.  The
               -mfprnd option allows GCC to generate the FP round to integer
               instructions implemented on the POWER5+ processor and other
               processors that support the PowerPC V2.03 architecture.  The -mcmpb
               option allows GCC to generate the compare bytes instruction
               implemented on the POWER6 processor and other processors that
               support the PowerPC V2.05 architecture.  The -mmfpgpr option allows
               GCC to generate the FP move to/from general purpose register
               instructions implemented on the POWER6X processor and other
               processors that support the extended PowerPC V2.05 architecture.
               The -mhard-dfp option allows GCC to generate the decimal floating
               point instructions implemented on some POWER processors.
    
               The -mpowerpc64 option allows GCC to generate the additional 64-bit
               instructions that are found in the full PowerPC64 architecture and
               to treat GPRs as 64-bit, doubleword quantities.  GCC defaults to
               -mno-powerpc64.
    
               If you specify both -mno-power and -mno-powerpc, GCC will use only
               the instructions in the common subset of both architectures plus
               some special AIX common-mode calls, and will not use the MQ
               register.  Specifying both -mpower and -mpowerpc permits GCC to use
               any instruction from either architecture and to allow use of the MQ
               register; specify this for the Motorola MPC601.
    
           -mnew-mnemonics
           -mold-mnemonics
               Select which mnemonics to use in the generated assembler code.
               With -mnew-mnemonics, GCC uses the assembler mnemonics defined for
               the PowerPC architecture.  With -mold-mnemonics it uses the
               assembler mnemonics defined for the POWER architecture.
               Instructions defined in only one architecture have only one
               mnemonic; GCC uses that mnemonic irrespective of which of these
               options is specified.
    
               GCC defaults to the mnemonics appropriate for the architecture in
               use.  Specifying -mcpu=cpu_type sometimes overrides the value of
               -mcpu=common selects a completely generic processor.  Code
               generated under this option will run on any POWER or PowerPC
               processor.  GCC will use only the instructions in the common subset
               of both architectures, and will not use the MQ register.  GCC
               assumes a generic processor model for scheduling purposes.
    
               -mcpu=power, -mcpu=power2, -mcpu=powerpc, and -mcpu=powerpc64
               specify generic POWER, POWER2, pure 32-bit PowerPC (i.e., not
               MPC601), and 64-bit PowerPC architecture machine types, with an
               appropriate, generic processor model assumed for scheduling
               purposes.
    
               The other options specify a specific processor.  Code generated
               under those options will run best on that processor, and may not
               run at all on others.
    
               The -mcpu options automatically enable or disable the following
               options:
    
               -maltivec  -mfprnd  -mhard-float  -mmfcrf  -mmultiple
               -mnew-mnemonics  -mpopcntb -mpopcntd  -mpower  -mpower2
               -mpowerpc64 -mpowerpc-gpopt  -mpowerpc-gfxopt  -msingle-float
               -mdouble-float -msimple-fpu -mstring  -mmulhw  -mdlmzb  -mmfpgpr
               -mvsx
    
               The particular options set for any particular CPU will vary between
               compiler versions, depending on what setting seems to produce
               optimal code for that CPU; it doesn't necessarily reflect the
               actual hardware's capabilities.  If you wish to set an individual
               option to a particular value, you may specify it after the -mcpu
               option, like -mcpu=970 -mno-altivec.
    
               On AIX, the -maltivec and -mpowerpc64 options are not enabled or
               disabled by the -mcpu option at present because AIX does not have
               full support for these options.  You may still enable or disable
               them individually if you're sure it'll work in your environment.
    
           -mtune=cpu_type
               Set the instruction scheduling parameters for machine type
               cpu_type, but do not set the architecture type, register usage, or
               choice of mnemonics, as -mcpu=cpu_type would.  The same values for
               cpu_type are used for -mtune as for -mcpu.  If both are specified,
               the code generated will use the architecture, registers, and
               mnemonics set by -mcpu, but the scheduling parameters set by
               -mtune.
    
           -mcmodel=small
               Generate PowerPC64 code for the small model: The TOC is limited to
               64k.
    
           -mcmodel=medium
               Generate PowerPC64 code for the medium model: The TOC and other
               the domain values not include Infinities, denormals or zero
               denominator.
    
           -maltivec
           -mno-altivec
               Generate code that uses (does not use) AltiVec instructions, and
               also enable the use of built-in functions that allow more direct
               access to the AltiVec instruction set.  You may also need to set
               -mabi=altivec to adjust the current ABI with AltiVec ABI
               enhancements.
    
           -mvrsave
           -mno-vrsave
               Generate VRSAVE instructions when generating AltiVec code.
    
           -mgen-cell-microcode
               Generate Cell microcode instructions
    
           -mwarn-cell-microcode
               Warning when a Cell microcode instruction is going to emitted.  An
               example of a Cell microcode instruction is a variable shift.
    
           -msecure-plt
               Generate code that allows ld and ld.so to build executables and
               shared libraries with non-exec .plt and .got sections.  This is a
               PowerPC 32-bit SYSV ABI option.
    
           -mbss-plt
               Generate code that uses a BSS .plt section that ld.so fills in, and
               requires .plt and .got sections that are both writable and
               executable.  This is a PowerPC 32-bit SYSV ABI option.
    
           -misel
           -mno-isel
               This switch enables or disables the generation of ISEL
               instructions.
    
           -misel=yes/no
               This switch has been deprecated.  Use -misel and -mno-isel instead.
    
           -mspe
           -mno-spe
               This switch enables or disables the generation of SPE simd
               instructions.
    
           -mpaired
           -mno-paired
               This switch enables or disables the generation of PAIRED simd
               instructions.
    
           -mspe=yes/no
               This option has been deprecated.  Use -mspe and -mno-spe instead.
               floating point operations.
    
               The argument double enables the use of single and double-precision
               floating point operations.
    
               The argument no disables floating point operations on the general
               purpose registers.
    
               This option is currently only available on the MPC854x.
    
           -m32
           -m64
               Generate code for 32-bit or 64-bit environments of Darwin and SVR4
               targets (including GNU/Linux).  The 32-bit environment sets int,
               long and pointer to 32 bits and generates code that runs on any
               PowerPC variant.  The 64-bit environment sets int to 32 bits and
               long and pointer to 64 bits, and generates code for PowerPC64, as
               for -mpowerpc64.
    
           -mfull-toc
           -mno-fp-in-toc
           -mno-sum-in-toc
           -mminimal-toc
               Modify generation of the TOC (Table Of Contents), which is created
               for every executable file.  The -mfull-toc option is selected by
               default.  In that case, GCC will allocate at least one TOC entry
               for each unique non-automatic variable reference in your program.
               GCC will also place floating-point constants in the TOC.  However,
               only 16,384 entries are available in the TOC.
    
               If you receive a linker error message that saying you have
               overflowed the available TOC space, you can reduce the amount of
               TOC space used with the -mno-fp-in-toc and -mno-sum-in-toc options.
               -mno-fp-in-toc prevents GCC from putting floating-point constants
               in the TOC and -mno-sum-in-toc forces GCC to generate code to
               calculate the sum of an address and a constant at run-time instead
               of putting that sum into the TOC.  You may specify one or both of
               these options.  Each causes GCC to produce very slightly slower and
               larger code at the expense of conserving TOC space.
    
               If you still run out of space in the TOC even when you specify both
               of these options, specify -mminimal-toc instead.  This option
               causes GCC to make only one TOC entry for every file.  When you
               specify this option, GCC will produce code that is slower and
               larger but which uses extremely little TOC space.  You may wish to
               use this option only on files that contain less frequently executed
               code.
    
           -maix64
           -maix32
               Enable 64-bit AIX ABI and calling convention: 64-bit pointers,
               64-bit "long" type, and the infrastructure needed to support them.
               The AIX calling convention was extended but not initially
               documented to handle an obscure K&R C case of calling a function
               that takes the address of its arguments with fewer arguments than
               declared.  IBM XL compilers access floating point arguments which
               do not fit in the RSA from the stack when a subroutine is compiled
               without optimization.  Because always storing floating-point
               arguments on the stack is inefficient and rarely needed, this
               option is not enabled by default and only is necessary when calling
               subroutines compiled by IBM XL compilers without optimization.
    
           -mpe
               Support IBM RS/6000 SP Parallel Environment (PE).  Link an
               application written to use message passing with special startup
               code to enable the application to run.  The system must have PE
               installed in the standard location (/usr/lpp/ppe.poe/), or the
               specs file must be overridden with the -specs= option to specify
               the appropriate directory location.  The Parallel Environment does
               not support threads, so the -mpe option and the -pthread option are
               incompatible.
    
           -malign-natural
           -malign-power
               On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option
               -malign-natural overrides the ABI-defined alignment of larger
               types, such as floating-point doubles, on their natural size-based
               boundary.  The option -malign-power instructs GCC to follow the
               ABI-specified alignment rules.  GCC defaults to the standard
               alignment defined in the ABI.
    
               On 64-bit Darwin, natural alignment is the default, and
               -malign-power is not supported.
    
           -msoft-float
           -mhard-float
               Generate code that does not use (uses) the floating-point register
               set.  Software floating point emulation is provided if you use the
               -msoft-float option, and pass the option to GCC when linking.
    
           -msingle-float
           -mdouble-float
               Generate code for single or double-precision floating point
               operations.  -mdouble-float implies -msingle-float.
    
           -msimple-fpu
               Do not generate sqrt and div instructions for hardware floating
               point unit.
    
           -mfpu
               Specify type of floating point unit.  Valid values are sp_lite
               (equivalent to -msingle-float -msimple-fpu), dp_lite (equivalent to
               -mdouble-float -msimple-fpu), sp_full (equivalent to
               -msingle-float), and dp_full (equivalent to -mdouble-float).
               mode.
    
           -mstring
           -mno-string
               Generate code that uses (does not use) the load string instructions
               and the store string word instructions to save multiple registers
               and do small block moves.  These instructions are generated by
               default on POWER systems, and not generated on PowerPC systems.  Do
               not use -mstring on little endian PowerPC systems, since those
               instructions do not work when the processor is in little endian
               mode.  The exceptions are PPC740 and PPC750 which permit the
               instructions usage in little endian mode.
    
           -mupdate
           -mno-update
               Generate code that uses (does not use) the load or store
               instructions that update the base register to the address of the
               calculated memory location.  These instructions are generated by
               default.  If you use -mno-update, there is a small window between
               the time that the stack pointer is updated and the address of the
               previous frame is stored, which means code that walks the stack
               frame across interrupts or signals may get corrupted data.
    
           -mavoid-indexed-addresses
           -mno-avoid-indexed-addresses
               Generate code that tries to avoid (not avoid) the use of indexed
               load or store instructions. These instructions can incur a
               performance penalty on Power6 processors in certain situations,
               such as when stepping through large arrays that cross a 16M
               boundary.  This option is enabled by default when targetting Power6
               and disabled otherwise.
    
           -mfused-madd
           -mno-fused-madd
               Generate code that uses (does not use) the floating point multiply
               and accumulate instructions.  These instructions are generated by
               default if hardware floating is used.
    
           -mmulhw
           -mno-mulhw
               Generate code that uses (does not use) the half-word multiply and
               multiply-accumulate instructions on the IBM 405, 440 and 464
               processors.  These instructions are generated by default when
               targetting those processors.
    
           -mdlmzb
           -mno-dlmzb
               Generate code that uses (does not use) the string-search dlmzb
               instruction on the IBM 405, 440 and 464 processors.  This
               instruction is generated by default when targetting those
               processors.
    
               On System V.4 and embedded PowerPC systems do not (do) assume that
               unaligned memory references will be handled by the system.
    
           -mrelocatable
           -mno-relocatable
               On embedded PowerPC systems generate code that allows (does not
               allow) the program to be relocated to a different address at
               runtime.  If you use -mrelocatable on any module, all objects
               linked together must be compiled with -mrelocatable or
               -mrelocatable-lib.
    
           -mrelocatable-lib
           -mno-relocatable-lib
               On embedded PowerPC systems generate code that allows (does not
               allow) the program to be relocated to a different address at
               runtime.  Modules compiled with -mrelocatable-lib can be linked
               with either modules compiled without -mrelocatable and
               -mrelocatable-lib or with modules compiled with the -mrelocatable
               options.
    
           -mno-toc
           -mtoc
               On System V.4 and embedded PowerPC systems do not (do) assume that
               register 2 contains a pointer to a global area pointing to the
               addresses used in the program.
    
           -mlittle
           -mlittle-endian
               On System V.4 and embedded PowerPC systems compile code for the
               processor in little endian mode.  The -mlittle-endian option is the
               same as -mlittle.
    
           -mbig
           -mbig-endian
               On System V.4 and embedded PowerPC systems compile code for the
               processor in big endian mode.  The -mbig-endian option is the same
               as -mbig.
    
           -mdynamic-no-pic
               On Darwin and Mac OS X systems, compile code so that it is not
               relocatable, but that its external references are relocatable.  The
               resulting code is suitable for applications, but not shared
               libraries.
    
           -mprioritize-restricted-insns=priority
               This option controls the priority that is assigned to dispatch-slot
               restricted instructions during the second scheduling pass.  The
               argument priority takes the value 0/1/2 to assign
               no/highest/second-highest priority to dispatch slot restricted
               instructions.
    
           -msched-costly-dep=dependence_type
               dependent insns into separate groups.  Insert exactly as many nops
               as needed to force an insn to a new group, according to the
               estimated processor grouping.  number: Insert nops to force costly
               dependent insns into separate groups.  Insert number nops to force
               an insn to a new group.
    
           -mcall-sysv
               On System V.4 and embedded PowerPC systems compile code using
               calling conventions that adheres to the March 1995 draft of the
               System V Application Binary Interface, PowerPC processor
               supplement.  This is the default unless you configured GCC using
               powerpc-*-eabiaix.
    
           -mcall-sysv-eabi
               Specify both -mcall-sysv and -meabi options.
    
           -mcall-sysv-noeabi
               Specify both -mcall-sysv and -mno-eabi options.
    
           -mcall-solaris
               On System V.4 and embedded PowerPC systems compile code for the
               Solaris operating system.
    
           -mcall-linux
               On System V.4 and embedded PowerPC systems compile code for the
               Linux-based GNU system.
    
           -mcall-gnu
               On System V.4 and embedded PowerPC systems compile code for the
               Hurd-based GNU system.
    
           -mcall-netbsd
               On System V.4 and embedded PowerPC systems compile code for the
               NetBSD operating system.
    
           -maix-struct-return
               Return all structures in memory (as specified by the AIX ABI).
    
           -msvr4-struct-return
               Return structures smaller than 8 bytes in registers (as specified
               by the SVR4 ABI).
    
           -mabi=abi-type
               Extend the current ABI with a particular extension, or remove such
               extension.  Valid values are altivec, no-altivec, spe, no-spe,
               ibmlongdouble, ieeelongdouble.
    
           -mabi=spe
               Extend the current ABI with SPE ABI extensions.  This does not
               change the default ABI, instead it adds the SPE ABI extensions to
               the current ABI.
    
               variable argument functions are properly prototyped.  Otherwise,
               the compiler must insert an instruction before every non prototyped
               call to set or clear bit 6 of the condition code register (CR) to
               indicate whether floating point values were passed in the floating
               point registers in case the function takes a variable arguments.
               With -mprototype, only calls to prototyped variable argument
               functions will set or clear the bit.
    
           -msim
               On embedded PowerPC systems, assume that the startup module is
               called sim-crt0.o and that the standard C libraries are libsim.a
               and libc.a.  This is the default for powerpc-*-eabisim
               configurations.
    
           -mmvme
               On embedded PowerPC systems, assume that the startup module is
               called crt0.o and the standard C libraries are libmvme.a and
               libc.a.
    
           -mads
               On embedded PowerPC systems, assume that the startup module is
               called crt0.o and the standard C libraries are libads.a and libc.a.
    
           -myellowknife
               On embedded PowerPC systems, assume that the startup module is
               called crt0.o and the standard C libraries are libyk.a and libc.a.
    
           -mvxworks
               On System V.4 and embedded PowerPC systems, specify that you are
               compiling for a VxWorks system.
    
           -memb
               On embedded PowerPC systems, set the PPC_EMB bit in the ELF flags
               header to indicate that eabi extended relocations are used.
    
           -meabi
           -mno-eabi
               On System V.4 and embedded PowerPC systems do (do not) adhere to
               the Embedded Applications Binary Interface (eabi) which is a set of
               modifications to the System V.4 specifications.  Selecting -meabi
               means that the stack is aligned to an 8 byte boundary, a function
               "__eabi" is called to from "main" to set up the eabi environment,
               and the -msdata option can use both "r2" and "r13" to point to two
               separate small data areas.  Selecting -mno-eabi means that the
               stack is aligned to a 16 byte boundary, do not call an
               initialization function from "main", and the -msdata option will
               only use "r13" to point to a single small data area.  The -meabi
               option is on by default if you configured GCC using one of the
               powerpc*-*-eabi* options.
    
           -msdata=eabi
               On System V.4 and embedded PowerPC systems, put small initialized
    
           -msdata=default
           -msdata
               On System V.4 and embedded PowerPC systems, if -meabi is used,
               compile code the same as -msdata=eabi, otherwise compile code the
               same as -msdata=sysv.
    
           -msdata=data
               On System V.4 and embedded PowerPC systems, put small global data
               in the .sdata section.  Put small uninitialized global data in the
               .sbss section.  Do not use register "r13" to address small data
               however.  This is the default behavior unless other -msdata options
               are used.
    
           -msdata=none
           -mno-sdata
               On embedded PowerPC systems, put all initialized global and static
               data in the .data section, and all uninitialized data in the .bss
               section.
    
           -G num
               On embedded PowerPC systems, put global and static items less than
               or equal to num bytes into the small data or bss sections instead
               of the normal data or bss section.  By default, num is 8.  The -G
               num switch is also passed to the linker.  All modules should be
               compiled with the same -G num value.
    
           -mregnames
           -mno-regnames
               On System V.4 and embedded PowerPC systems do (do not) emit
               register names in the assembly language output using symbolic
               forms.
    
           -mlongcall
           -mno-longcall
               By default assume that all calls are far away so that a longer more
               expensive calling sequence is required.  This is required for calls
               further than 32 megabytes (33,554,432 bytes) from the current
               location.  A short call will be generated if the compiler knows the
               call cannot be that far away.  This setting can be overridden by
               the "shortcall" function attribute, or by "#pragma longcall(0)".
    
               Some linkers are capable of detecting out-of-range calls and
               generating glue code on the fly.  On these systems, long calls are
               unnecessary and generate slower code.  As of this writing, the AIX
               linker can do this, as can the GNU linker for PowerPC/64.  It is
               planned to add this feature to the GNU linker for 32-bit PowerPC
               systems as well.
    
               On Darwin/PPC systems, "#pragma longcall" will generate "jbsr
               callee, L42", plus a "branch island" (glue code).  The two target
               addresses represent the callee and the "branch island".  The
    
           -pthread
               Adds support for multithreading with the pthreads library.  This
               option sets flags for both the preprocessor and linker.
    
       S/390 and zSeries Options
           These are the -m options defined for the S/390 and zSeries
           architecture.
    
           -mhard-float
           -msoft-float
               Use (do not use) the hardware floating-point instructions and
               registers for floating-point operations.  When -msoft-float is
               specified, functions in libgcc.a will be used to perform floating-
               point operations.  When -mhard-float is specified, the compiler
               generates IEEE floating-point instructions.  This is the default.
    
           -mhard-dfp
           -mno-hard-dfp
               Use (do not use) the hardware decimal-floating-point instructions
               for decimal-floating-point operations.  When -mno-hard-dfp is
               specified, functions in libgcc.a will be used to perform decimal-
               floating-point operations.  When -mhard-dfp is specified, the
               compiler generates decimal-floating-point hardware instructions.
               This is the default for -march=z9-ec or higher.
    
           -mlong-double-64
           -mlong-double-128
               These switches control the size of "long double" type. A size of
               64bit makes the "long double" type equivalent to the "double" type.
               This is the default.
    
           -mbackchain
           -mno-backchain
               Store (do not store) the address of the caller's frame as backchain
               pointer into the callee's stack frame.  A backchain may be needed
               to allow debugging using tools that do not understand DWARF-2 call
               frame information.  When -mno-packed-stack is in effect, the
               backchain pointer is stored at the bottom of the stack frame; when
               -mpacked-stack is in effect, the backchain is placed into the
               topmost word of the 96/160 byte register save area.
    
               In general, code compiled with -mbackchain is call-compatible with
               code compiled with -mmo-backchain; however, use of the backchain
               for debugging purposes usually requires that the whole binary is
               built with -mbackchain.  Note that the combination of -mbackchain,
               -mpacked-stack and -mhard-float is not supported.  In order to
               build a linux kernel use -msoft-float.
    
               The default is to not maintain the backchain.
    
           -mpacked-stack
           -mno-packed-stack
               S/390 or zSeries generated code that uses the stack frame backchain
               at run time, not just for debugging purposes.  Such code is not
               call-compatible with code compiled with -mpacked-stack.  Also, note
               that the combination of -mbackchain, -mpacked-stack and
               -mhard-float is not supported.  In order to build a linux kernel
               use -msoft-float.
    
               The default is to not use the packed stack layout.
    
           -msmall-exec
           -mno-small-exec
               Generate (or do not generate) code using the "bras" instruction to
               do subroutine calls.  This only works reliably if the total
               executable size does not exceed 64k.  The default is to use the
               "basr" instruction instead, which does not have this limitation.
    
           -m64
           -m31
               When -m31 is specified, generate code compliant to the GNU/Linux
               for S/390 ABI.  When -m64 is specified, generate code compliant to
               the GNU/Linux for zSeries ABI.  This allows GCC in particular to
               generate 64-bit instructions.  For the s390 targets, the default is
               -m31, while the s390x targets default to -m64.
    
           -mzarch
           -mesa
               When -mzarch is specified, generate code using the instructions
               available on z/Architecture.  When -mesa is specified, generate
               code using the instructions available on ESA/390.  Note that -mesa
               is not possible with -m64.  When generating code compliant to the
               GNU/Linux for S/390 ABI, the default is -mesa.  When generating
               code compliant to the GNU/Linux for zSeries ABI, the default is
               -mzarch.
    
           -mmvcle
           -mno-mvcle
               Generate (or do not generate) code using the "mvcle" instruction to
               perform block moves.  When -mno-mvcle is specified, use a "mvc"
               loop instead.  This is the default unless optimizing for size.
    
           -mdebug
           -mno-debug
               Print (or do not print) additional debug information when
               compiling.  The default is to not print debug information.
    
           -march=cpu-type
               Generate code that will run on cpu-type, which is the name of a
               system representing a certain processor type.  Possible values for
               cpu-type are g5, g6, z900, z990, z9-109, z9-ec and z10.  When
               generating code using the instructions available on z/Architecture,
               the default is -march=z900.  Otherwise, the default is -march=g5.
    
               Generate code that uses (does not use) the floating point multiply
               and accumulate instructions.  These instructions are generated by
               default if hardware floating point is used.
    
           -mwarn-framesize=framesize
               Emit a warning if the current function exceeds the given frame
               size.  Because this is a compile time check it doesn't need to be a
               real problem when the program runs.  It is intended to identify
               functions which most probably cause a stack overflow.  It is useful
               to be used in an environment with limited stack size e.g. the linux
               kernel.
    
           -mwarn-dynamicstack
               Emit a warning if the function calls alloca or uses dynamically
               sized arrays.  This is generally a bad idea with a limited stack
               size.
    
           -mstack-guard=stack-guard
           -mstack-size=stack-size
               If these options are provided the s390 back end emits additional
               instructions in the function prologue which trigger a trap if the
               stack size is stack-guard bytes above the stack-size (remember that
               the stack on s390 grows downward).  If the stack-guard option is
               omitted the smallest power of 2 larger than the frame size of the
               compiled function is chosen.  These options are intended to be used
               to help debugging stack overflow problems.  The additionally
               emitted code causes only little overhead and hence can also be used
               in production like systems without greater performance degradation.
               The given values have to be exact powers of 2 and stack-size has to
               be greater than stack-guard without exceeding 64k.  In order to be
               efficient the extra code makes the assumption that the stack starts
               at an address aligned to the value given by stack-size.  The stack-
               guard option can only be used in conjunction with stack-size.
    
           -mhotpatch=pre-halfwords,post-halfwords
               If the hotpatch option is enabled, a "hot-patching" function
               prologue is generated for all functions in the compilation unit.
               The funtion label is prepended with the given number of two-byte
               NOP instructions (pre-halfwords, maximum 1000000).  After the
               label, 2 * post-halfwords bytes are appended, using the largest NOP
               like instructions the architecture allows (maximum 1000000).
    
               If both arguments are zero, hotpatching is disabled.
    
               This option can be overridden for individual functions with the
               "hotpatch" attribute.
    
       Score Options
           These options are defined for Score implementations:
    
           -meb
               Compile code for big endian mode.  This is the default.
    
           -mscore5
               Specify the SCORE5 as the target architecture.
    
           -mscore5u
               Specify the SCORE5U of the target architecture.
    
           -mscore7
               Specify the SCORE7 as the target architecture. This is the default.
    
           -mscore7d
               Specify the SCORE7D as the target architecture.
    
       SH Options
           These -m options are defined for the SH implementations:
    
           -m1 Generate code for the SH1.
    
           -m2 Generate code for the SH2.
    
           -m2e
               Generate code for the SH2e.
    
           -m3 Generate code for the SH3.
    
           -m3e
               Generate code for the SH3e.
    
           -m4-nofpu
               Generate code for the SH4 without a floating-point unit.
    
           -m4-single-only
               Generate code for the SH4 with a floating-point unit that only
               supports single-precision arithmetic.
    
           -m4-single
               Generate code for the SH4 assuming the floating-point unit is in
               single-precision mode by default.
    
           -m4 Generate code for the SH4.
    
           -m4a-nofpu
               Generate code for the SH4al-dsp, or for a SH4a in such a way that
               the floating-point unit is not used.
    
           -m4a-single-only
               Generate code for the SH4a, in such a way that no double-precision
               floating point operations are used.
    
           -m4a-single
               Generate code for the SH4a assuming the floating-point unit is in
               single-precision mode by default.
    
               calling conventions, and thus some functions from the standard C
               library will not work unless you recompile it first with -mdalign.
    
           -mrelax
               Shorten some address references at link time, when possible; uses
               the linker option -relax.
    
           -mbigtable
               Use 32-bit offsets in "switch" tables.  The default is to use
               16-bit offsets.
    
           -mbitops
               Enable the use of bit manipulation instructions on SH2A.
    
           -mfmovd
               Enable the use of the instruction "fmovd".
    
           -mhitachi
               Comply with the calling conventions defined by Renesas.
    
           -mrenesas
               Comply with the calling conventions defined by Renesas.
    
           -mno-renesas
               Comply with the calling conventions defined for GCC before the
               Renesas conventions were available.  This option is the default for
               all targets of the SH toolchain except for sh-symbianelf.
    
           -mnomacsave
               Mark the "MAC" register as call-clobbered, even if -mhitachi is
               given.
    
           -mieee
               Increase IEEE-compliance of floating-point code.  At the moment,
               this is equivalent to -fno-finite-math-only.  When generating 16
               bit SH opcodes, getting IEEE-conforming results for comparisons of
               NANs / infinities incurs extra overhead in every floating point
               comparison, therefore the default is set to -ffinite-math-only.
    
           -minline-ic_invalidate
               Inline code to invalidate instruction cache entries after setting
               up nested function trampolines.  This option has no effect if
               -musermode is in effect and the selected code generation option
               (e.g. -m4) does not allow the use of the icbi instruction.  If the
               selected code generation option does not allow the use of the icbi
               instruction, and -musermode is not in effect, the inlined code will
               manipulate the instruction cache address array directly with an
               associative write.  This not only requires privileged mode, but it
               will also fail if the cache line had been mapped via the TLB and
               has become unmapped.
    
           -misize
           -musermode
               Don't generate privileged mode only code; implies
               -mno-inline-ic_invalidate if the inlined code would not work in
               user mode.  This is the default when the target is "sh-*-linux*".
    
           -multcost=number
               Set the cost to assume for a multiply insn.
    
           -mdiv=strategy
               Set the division strategy to use for SHmedia code.  strategy must
               be one of: call, call2, fp, inv, inv:minlat, inv20u, inv20l,
               inv:call, inv:call2, inv:fp .  "fp" performs the operation in
               floating point.  This has a very high latency, but needs only a few
               instructions, so it might be a good choice if your code has enough
               easily exploitable ILP to allow the compiler to schedule the
               floating point instructions together with other instructions.
               Division by zero causes a floating point exception.  "inv" uses
               integer operations to calculate the inverse of the divisor, and
               then multiplies the dividend with the inverse.  This strategy
               allows cse and hoisting of the inverse calculation.  Division by
               zero calculates an unspecified result, but does not trap.
               "inv:minlat" is a variant of "inv" where if no cse / hoisting
               opportunities have been found, or if the entire operation has been
               hoisted to the same place, the last stages of the inverse
               calculation are intertwined with the final multiply to reduce the
               overall latency, at the expense of using a few more instructions,
               and thus offering fewer scheduling opportunities with other code.
               "call" calls a library function that usually implements the
               inv:minlat strategy.  This gives high code density for
               m5-*media-nofpu compilations.  "call2" uses a different entry point
               of the same library function, where it assumes that a pointer to a
               lookup table has already been set up, which exposes the pointer
               load to cse / code hoisting optimizations.  "inv:call", "inv:call2"
               and "inv:fp" all use the "inv" algorithm for initial code
               generation, but if the code stays unoptimized, revert to the
               "call", "call2", or "fp" strategies, respectively.  Note that the
               potentially-trapping side effect of division by zero is carried by
               a separate instruction, so it is possible that all the integer
               instructions are hoisted out, but the marker for the side effect
               stays where it is.  A recombination to fp operations or a call is
               not possible in that case.  "inv20u" and "inv20l" are variants of
               the "inv:minlat" strategy.  In the case that the inverse
               calculation was nor separated from the multiply, they speed up
               division where the dividend fits into 20 bits (plus sign where
               applicable), by inserting a test to skip a number of operations in
               this case; this test slows down the case of larger dividends.
               inv20u assumes the case of a such a small dividend to be unlikely,
               and inv20l assumes it to be likely.
    
           -mdivsi3_libfunc=name
               Set the name of the library function used for 32 bit signed
               division to name.  This only affect the name used in the call and
               TARGET_ADJUST_UNROLL_MAX target hook.
    
           -mindexed-addressing
               Enable the use of the indexed addressing mode for
               SHmedia32/SHcompact.  This is only safe if the hardware and/or OS
               implement 32 bit wrap-around semantics for the indexed addressing
               mode.  The architecture allows the implementation of processors
               with 64 bit MMU, which the OS could use to get 32 bit addressing,
               but since no current hardware implementation supports this or any
               other way to make the indexed addressing mode safe to use in the 32
               bit ABI, the default is -mno-indexed-addressing.
    
           -mgettrcost=number
               Set the cost assumed for the gettr instruction to number.  The
               default is 2 if -mpt-fixed is in effect, 100 otherwise.
    
           -mpt-fixed
               Assume pt* instructions won't trap.  This will generally generate
               better scheduled code, but is unsafe on current hardware.  The
               current architecture definition says that ptabs and ptrel trap when
               the target anded with 3 is 3.  This has the unintentional effect of
               making it unsafe to schedule ptabs / ptrel before a branch, or
               hoist it out of a loop.  For example, __do_global_ctors, a part of
               libgcc that runs constructors at program startup, calls functions
               in a list which is delimited by -1.  With the -mpt-fixed option,
               the ptabs will be done before testing against -1.  That means that
               all the constructors will be run a bit quicker, but when the loop
               comes to the end of the list, the program crashes because ptabs
               loads -1 into a target register.  Since this option is unsafe for
               any hardware implementing the current architecture specification,
               the default is -mno-pt-fixed.  Unless the user specifies a specific
               cost with -mgettrcost, -mno-pt-fixed also implies -mgettrcost=100;
               this deters register allocation using target registers for storing
               ordinary integers.
    
           -minvalid-symbols
               Assume symbols might be invalid.  Ordinary function symbols
               generated by the compiler will always be valid to load with
               movi/shori/ptabs or movi/shori/ptrel, but with assembler and/or
               linker tricks it is possible to generate symbols that will cause
               ptabs / ptrel to trap.  This option is only meaningful when
               -mno-pt-fixed is in effect.  It will then prevent cross-basic-block
               cse, hoisting and most scheduling of symbol loads.  The default is
               -mno-invalid-symbols.
    
       SPARC Options
           These -m options are supported on the SPARC:
    
           -mno-app-regs
           -mapp-regs
               Specify -mapp-regs to generate output using the global registers 2
               through 4, which the SPARC SVR4 ABI reserves for applications.
               Warning: the requisite libraries are not available for all SPARC
               targets.  Normally the facilities of the machine's usual C compiler
               are used, but this cannot be done directly in cross-compilation.
               You must make your own arrangements to provide suitable library
               functions for cross-compilation.  The embedded targets sparc-*-aout
               and sparclite-*-* do provide software floating point support.
    
               -msoft-float changes the calling convention in the output file;
               therefore, it is only useful if you compile all of a program with
               this option.  In particular, you need to compile libgcc.a, the
               library that comes with GCC, with -msoft-float in order for this to
               work.
    
           -mhard-quad-float
               Generate output containing quad-word (long double) floating point
               instructions.
    
           -msoft-quad-float
               Generate output containing library calls for quad-word (long
               double) floating point instructions.  The functions called are
               those specified in the SPARC ABI.  This is the default.
    
               As of this writing, there are no SPARC implementations that have
               hardware support for the quad-word floating point instructions.
               They all invoke a trap handler for one of these instructions, and
               then the trap handler emulates the effect of the instruction.
               Because of the trap handler overhead, this is much slower than
               calling the ABI library routines.  Thus the -msoft-quad-float
               option is the default.
    
           -mno-unaligned-doubles
           -munaligned-doubles
               Assume that doubles have 8 byte alignment.  This is the default.
    
               With -munaligned-doubles, GCC assumes that doubles have 8 byte
               alignment only if they are contained in another type, or if they
               have an absolute address.  Otherwise, it assumes they have 4 byte
               alignment.  Specifying this option avoids some rare compatibility
               problems with code generated by other compilers.  It is not the
               default because it results in a performance loss, especially for
               floating point code.
    
           -mno-faster-structs
           -mfaster-structs
               With -mfaster-structs, the compiler assumes that structures should
               have 8 byte alignment.  This enables the use of pairs of "ldd" and
               "std" instructions for copies in structure assignment, in place of
               twice as many "ld" and "st" pairs.  However, the use of this
               changed alignment directly violates the SPARC ABI.  Thus, it's
               intended only for use on targets where the developer acknowledges
               that their resulting code will not be directly in line with the
               rules of the ABI.
               This option is only available on SunOS and Solaris.
    
           -mcpu=cpu_type
               Set the instruction set, register set, and instruction scheduling
               parameters for machine type cpu_type.  Supported values for
               cpu_type are v7, cypress, v8, supersparc, sparclite, f930, f934,
               hypersparc, sparclite86x, sparclet, tsc701, v9, ultrasparc,
               ultrasparc3, niagara and niagara2.
    
               Default instruction scheduling parameters are used for values that
               select an architecture and not an implementation.  These are v7,
               v8, sparclite, sparclet, v9.
    
               Here is a list of each supported architecture and their supported
               implementations.
    
                           v7:             cypress
                           v8:             supersparc, hypersparc
                           sparclite:      f930, f934, sparclite86x
                           sparclet:       tsc701
                           v9:             ultrasparc, ultrasparc3, niagara, niagara2
    
               By default (unless configured otherwise), GCC generates code for
               the V7 variant of the SPARC architecture.  With -mcpu=cypress, the
               compiler additionally optimizes it for the Cypress CY7C602 chip, as
               used in the SPARCStation/SPARCServer 3xx series.  This is also
               appropriate for the older SPARCStation 1, 2, IPX etc.
    
               With -mcpu=v8, GCC generates code for the V8 variant of the SPARC
               architecture.  The only difference from V7 code is that the
               compiler emits the integer multiply and integer divide instructions
               which exist in SPARC-V8 but not in SPARC-V7.  With
               -mcpu=supersparc, the compiler additionally optimizes it for the
               SuperSPARC chip, as used in the SPARCStation 10, 1000 and 2000
               series.
    
               With -mcpu=sparclite, GCC generates code for the SPARClite variant
               of the SPARC architecture.  This adds the integer multiply, integer
               divide step and scan ("ffs") instructions which exist in SPARClite
               but not in SPARC-V7.  With -mcpu=f930, the compiler additionally
               optimizes it for the Fujitsu MB86930 chip, which is the original
               SPARClite, with no FPU.  With -mcpu=f934, the compiler additionally
               optimizes it for the Fujitsu MB86934 chip, which is the more recent
               SPARClite with FPU.
    
               With -mcpu=sparclet, GCC generates code for the SPARClet variant of
               the SPARC architecture.  This adds the integer multiply,
               multiply/accumulate, integer divide step and scan ("ffs")
               instructions which exist in SPARClet but not in SPARC-V7.  With
               -mcpu=tsc701, the compiler additionally optimizes it for the TEMIC
               SPARClet chip.
    
               the option -mcpu=cpu_type would.
    
               The same values for -mcpu=cpu_type can be used for -mtune=cpu_type,
               but the only useful values are those that select a particular cpu
               implementation.  Those are cypress, supersparc, hypersparc, f930,
               f934, sparclite86x, tsc701, ultrasparc, ultrasparc3, niagara, and
               niagara2.
    
           -mv8plus
           -mno-v8plus
               With -mv8plus, GCC generates code for the SPARC-V8+ ABI.  The
               difference from the V8 ABI is that the global and out registers are
               considered 64-bit wide.  This is enabled by default on Solaris in
               32-bit mode for all SPARC-V9 processors.
    
           -mvis
           -mno-vis
               With -mvis, GCC generates code that takes advantage of the
               UltraSPARC Visual Instruction Set extensions.  The default is
               -mno-vis.
    
           These -m options are supported in addition to the above on SPARC-V9
           processors in 64-bit environments:
    
           -mlittle-endian
               Generate code for a processor running in little-endian mode.  It is
               only available for a few configurations and most notably not on
               Solaris and Linux.
    
           -m32
           -m64
               Generate code for a 32-bit or 64-bit environment.  The 32-bit
               environment sets int, long and pointer to 32 bits.  The 64-bit
               environment sets int to 32 bits and long and pointer to 64 bits.
    
           -mcmodel=medlow
               Generate code for the Medium/Low code model: 64-bit addresses,
               programs must be linked in the low 32 bits of memory.  Programs can
               be statically or dynamically linked.
    
           -mcmodel=medmid
               Generate code for the Medium/Middle code model: 64-bit addresses,
               programs must be linked in the low 44 bits of memory, the text and
               data segments must be less than 2GB in size and the data segment
               must be located within 2GB of the text segment.
    
           -mcmodel=medany
               Generate code for the Medium/Anywhere code model: 64-bit addresses,
               programs may be linked anywhere in memory, the text and data
               segments must be less than 2GB in size and the data segment must be
               located within 2GB of the text segment.
    
           These switches are supported in addition to the above on Solaris:
    
           -threads
               Add support for multithreading using the Solaris threads library.
               This option sets flags for both the preprocessor and linker.  This
               option does not affect the thread safety of object code produced by
               the compiler or that of libraries supplied with it.
    
           -pthreads
               Add support for multithreading using the POSIX threads library.
               This option sets flags for both the preprocessor and linker.  This
               option does not affect the thread safety of object code produced
               by the compiler or that of libraries supplied with it.
    
           -pthread
               This is a synonym for -pthreads.
    
       SPU Options
           These -m options are supported on the SPU:
    
           -mwarn-reloc
           -merror-reloc
               The loader for SPU does not handle dynamic relocations.  By
               default, GCC will give an error when it generates code that
               requires a dynamic relocation.  -mno-error-reloc disables the
               error, -mwarn-reloc will generate a warning instead.
    
           -msafe-dma
           -munsafe-dma
               Instructions which initiate or test completion of DMA must not be
               reordered with respect to loads and stores of the memory which is
               being accessed.  Users typically address this problem using the
               volatile keyword, but that can lead to inefficient code in places
               where the memory is known to not change.  Rather than mark the
               memory as volatile we treat the DMA instructions as potentially
               effecting all memory.  With -munsafe-dma users must use the
               volatile keyword to protect memory accesses.
    
           -mbranch-hints
               By default, GCC will generate a branch hint instruction to avoid
               pipeline stalls for always taken or probably taken branches.  A
               hint will not be generated closer than 8 instructions away from its
               branch.  There is little reason to disable them, except for
               debugging purposes, or to make an object a little bit smaller.
    
           -msmall-mem
           -mlarge-mem
               By default, GCC generates code assuming that addresses are never
               larger than 18 bits.  With -mlarge-mem code is generated that
               assumes a full 32 bit address.
    
           -mstdmain
           -mdual-nops=n
               By default, GCC will insert nops to increase dual issue when it
               expects it to increase performance.  n can be a value from 0 to 10.
               A smaller n will insert fewer nops.  10 is the default, 0 is the
               same as -mno-dual-nops.  Disabled with -Os.
    
           -mhint-max-nops=n
               Maximum number of nops to insert for a branch hint.  A branch hint
               must be at least 8 instructions away from the branch it is
               effecting.  GCC will insert up to n nops to enforce this, otherwise
               it will not generate the branch hint.
    
           -mhint-max-distance=n
               The encoding of the branch hint instruction limits the hint to be
               within 256 instructions of the branch it is effecting.  By default,
               GCC makes sure it is within 125.
    
           -msafe-hints
               Work around a hardware bug which causes the SPU to stall
               indefinitely.  By default, GCC will insert the "hbrp" instruction
               to make sure this stall won't happen.
    
       Options for System V
           These additional options are available on System V Release 4 for
           compatibility with other compilers on those systems:
    
           -G  Create a shared object.  It is recommended that -symbolic or
               -shared be used instead.
    
           -Qy Identify the versions of each tool used by the compiler, in a
               ".ident" assembler directive in the output.
    
           -Qn Refrain from adding ".ident" directives to the output file (this is
               the default).
    
           -YP,dirs
               Search the directories dirs, and no others, for libraries specified
               with -l.
    
           -Ym,dir
               Look in the directory dir to find the M4 preprocessor.  The
               assembler uses this option.
    
       V850 Options
           These -m options are defined for V850 implementations:
    
           -mlong-calls
           -mno-long-calls
               Treat all calls as being far away (near).  If calls are assumed to
               be far away, the compiler will always load the functions address up
               into a register, and call indirect through the pointer.
    
    
           -mspace
               Try to make the code as small as possible.  At present, this just
               turns on the -mep and -mprolog-function options.
    
           -mtda=n
               Put static or global variables whose size is n bytes or less into
               the tiny data area that register "ep" points to.  The tiny data
               area can hold up to 256 bytes in total (128 bytes for byte
               references).
    
           -msda=n
               Put static or global variables whose size is n bytes or less into
               the small data area that register "gp" points to.  The small data
               area can hold up to 64 kilobytes.
    
           -mzda=n
               Put static or global variables whose size is n bytes or less into
               the first 32 kilobytes of memory.
    
           -mv850
               Specify that the target processor is the V850.
    
           -mbig-switch
               Generate code suitable for big switch tables.  Use this option only
               if the assembler/linker complain about out of range branches within
               a switch table.
    
           -mapp-regs
               This option will cause r2 and r5 to be used in the code generated
               by the compiler.  This setting is the default.
    
           -mno-app-regs
               This option will cause r2 and r5 to be treated as fixed registers.
    
           -mv850e1
               Specify that the target processor is the V850E1.  The preprocessor
               constants __v850e1__ and __v850e__ will be defined if this option
               is used.
    
           -mv850e
               Specify that the target processor is the V850E.  The preprocessor
               constant __v850e__ will be defined if this option is used.
    
               If neither -mv850 nor -mv850e nor -mv850e1 are defined then a
               default target processor will be chosen and the relevant __v850*__
               preprocessor constant will be defined.
    
               The preprocessor constants __v850 and __v851__ are always defined,
               regardless of which processor variant is the target.
    
           -mdisable-callt
               assemble with the GNU assembler.
    
           -mg Output code for g-format floating point numbers instead of
               d-format.
    
       VxWorks Options
           The options in this section are defined for all VxWorks targets.
           Options specific to the target hardware are listed with the other
           options for that target.
    
           -mrtp
               GCC can generate code for both VxWorks kernels and real time
               processes (RTPs).  This option switches from the former to the
               latter.  It also defines the preprocessor macro "__RTP__".
    
           -non-static
               Link an RTP executable against shared libraries rather than static
               libraries.  The options -static and -shared can also be used for
               RTPs; -static is the default.
    
           -Bstatic
           -Bdynamic
               These options are passed down to the linker.  They are defined for
               compatibility with Diab.
    
           -Xbind-lazy
               Enable lazy binding of function calls.  This option is equivalent
               to -Wl,-z,now and is defined for compatibility with Diab.
    
           -Xbind-now
               Disable lazy binding of function calls.  This option is the default
               and is defined for compatibility with Diab.
    
       x86-64 Options
           These are listed under
    
       Xstormy16 Options
           These options are defined for Xstormy16:
    
           -msim
               Choose startup files and linker script suitable for the simulator.
    
       Xtensa Options
           These options are supported for Xtensa targets:
    
           -mconst16
           -mno-const16
               Enable or disable use of "CONST16" instructions for loading
               constant values.  The "CONST16" instruction is currently not a
               standard option from Tensilica.  When enabled, "CONST16"
               instructions are always used in place of the standard "L32R"
               instructions.  The use of "CONST16" is enabled by default only if
               also ensures that the program output is not sensitive to the
               compiler's ability to combine multiply and add/subtract operations.
    
           -mserialize-volatile
           -mno-serialize-volatile
               When this option is enabled, GCC inserts "MEMW" instructions before
               "volatile" memory references to guarantee sequential consistency.
               The default is -mserialize-volatile.  Use -mno-serialize-volatile
               to omit the "MEMW" instructions.
    
           -mtext-section-literals
           -mno-text-section-literals
               Control the treatment of literal pools.  The default is
               -mno-text-section-literals, which places literals in a separate
               section in the output file.  This allows the literal pool to be
               placed in a data RAM/ROM, and it also allows the linker to combine
               literal pools from separate object files to remove redundant
               literals and improve code size.  With -mtext-section-literals, the
               literals are interspersed in the text section in order to keep them
               as close as possible to their references.  This may be necessary
               for large assembly files.
    
           -mtarget-align
           -mno-target-align
               When this option is enabled, GCC instructs the assembler to
               automatically align instructions to reduce branch penalties at the
               expense of some code density.  The assembler attempts to widen
               density instructions to align branch targets and the instructions
               following call instructions.  If there are not enough preceding
               safe density instructions to align a target, no widening will be
               performed.  The default is -mtarget-align.  These options do not
               affect the treatment of auto-aligned instructions like "LOOP",
               which the assembler will always align, either by widening density
               instructions or by inserting no-op instructions.
    
           -mlongcalls
           -mno-longcalls
               When this option is enabled, GCC instructs the assembler to
               translate direct calls to indirect calls unless it can determine
               that the target of a direct call is in the range allowed by the
               call instruction.  This translation typically occurs for calls to
               functions in other source files.  Specifically, the assembler
               translates a direct "CALL" instruction into an "L32R" followed by a
               "CALLX" instruction.  The default is -mno-longcalls.  This option
               should be used in programs where the call target can potentially be
               out of range.  This option is implemented in the assembler, not the
               compiler, so the assembly code generated by GCC will still show
               direct call instructions---look at the disassembled object code to
               see the actual instructions.  Note that the assembler will use an
               indirect call for every cross-file call, not just those that really
               will be out of range.
    
               that indices used to access arrays are within the declared range.
               This is currently only supported by the Java and Fortran front-
               ends, where this option defaults to true and false respectively.
    
           -ftrapv
               This option generates traps for signed overflow on addition,
               subtraction, multiplication operations.
    
           -fwrapv
               This option instructs the compiler to assume that signed arithmetic
               overflow of addition, subtraction and multiplication wraps around
               using twos-complement representation.  This flag enables some
               optimizations and disables others.  This option is enabled by
               default for the Java front-end, as required by the Java language
               specification.
    
           -fexceptions
               Enable exception handling.  Generates extra code needed to
               propagate exceptions.  For some targets, this implies GCC will
               generate frame unwind information for all functions, which can
               produce significant data size overhead, although it does not affect
               execution.  If you do not specify this option, GCC will enable it
               by default for languages like C++ which normally require exception
               handling, and disable it for languages like C that do not normally
               require it.  However, you may need to enable this option when
               compiling C code that needs to interoperate properly with exception
               handlers written in C++.  You may also wish to disable this option
               if you are compiling older C++ programs that don't use exception
               handling.
    
           -fnon-call-exceptions
               Generate code that allows trapping instructions to throw
               exceptions.  Note that this requires platform-specific runtime
               support that does not exist everywhere.  Moreover, it only allows
               trapping instructions to throw exceptions, i.e. memory references
               or floating point instructions.  It does not allow exceptions to be
               thrown from arbitrary signal handlers such as "SIGALRM".
    
           -funwind-tables
               Similar to -fexceptions, except that it will just generate any
               needed static data, but will not affect the generated code in any
               other way.  You will normally not enable this option; instead, a
               language processor that needs this handling would enable it on your
               behalf.
    
           -fasynchronous-unwind-tables
               Generate unwind table in dwarf2 format, if supported by target
               machine.  The table is exact at each instruction boundary, so it
               can be used for stack unwinding from asynchronous events (such as
               debugger or garbage collector).
    
           -fpcc-struct-return
               switch.  Use it to conform to a non-default application binary
               interface.
    
           -freg-struct-return
               Return "struct" and "union" values in registers when possible.
               This is more efficient for small structures than
               -fpcc-struct-return.
    
               If you specify neither -fpcc-struct-return nor -freg-struct-return,
               GCC defaults to whichever convention is standard for the target.
               If there is no standard convention, GCC defaults to
               -fpcc-struct-return, except on targets where GCC is the principal
               compiler.  In those cases, we can choose the standard, and we chose
               the more efficient register return alternative.
    
               Warning: code compiled with the -freg-struct-return switch is not
               binary compatible with code compiled with the -fpcc-struct-return
               switch.  Use it to conform to a non-default application binary
               interface.
    
           -fshort-enums
               Allocate to an "enum" type only as many bytes as it needs for the
               declared range of possible values.  Specifically, the "enum" type
               will be equivalent to the smallest integer type which has enough
               room.
    
               Warning: the -fshort-enums switch causes GCC to generate code that
               is not binary compatible with code generated without that switch.
               Use it to conform to a non-default application binary interface.
    
           -fshort-double
               Use the same size for "double" as for "float".
    
               Warning: the -fshort-double switch causes GCC to generate code that
               is not binary compatible with code generated without that switch.
               Use it to conform to a non-default application binary interface.
    
           -fshort-wchar
               Override the underlying type for wchar_t to be short unsigned int
               instead of the default for the target.  This option is useful for
               building programs to run under WINE.
    
               Warning: the -fshort-wchar switch causes GCC to generate code that
               is not binary compatible with code generated without that switch.
               Use it to conform to a non-default application binary interface.
    
           -fno-common
               In C code, controls the placement of uninitialized global
               variables.  Unix C compilers have traditionally permitted multiple
               definitions of such variables in different compilation units by
               placing the variables in a common block.  This is the behavior
               specified by -fcommon, and is the default for GCC on most targets.
               Ignore the #ident directive.
    
           -finhibit-size-directive
               Don't output a ".size" assembler directive, or anything else that
               would cause trouble if the function is split in the middle, and the
               two halves are placed at locations far apart in memory.  This
               option is used when compiling crtstuff.c; you should not need to
               use it for anything else.
    
           -fverbose-asm
               Put extra commentary information in the generated assembly code to
               make it more readable.  This option is generally only of use to
               those who actually need to read the generated assembly code
               (perhaps while debugging the compiler itself).
    
               -fno-verbose-asm, the default, causes the extra information to be
               omitted and is useful when comparing two assembler files.
    
           -frecord-gcc-switches
               This switch causes the command line that was used to invoke the
               compiler to be recorded into the object file that is being created.
               This switch is only implemented on some targets and the exact
               format of the recording is target and binary file format dependent,
               but it usually takes the form of a section containing ASCII text.
               This switch is related to the -fverbose-asm switch, but that switch
               only records information in the assembler output file as comments,
               so it never reaches the object file.
    
           -fpic
               Generate position-independent code (PIC) suitable for use in a
               shared library, if supported for the target machine.  Such code
               accesses all constant addresses through a global offset table
               (GOT).  The dynamic loader resolves the GOT entries when the
               program starts (the dynamic loader is not part of GCC; it is part
               of the operating system).  If the GOT size for the linked
               executable exceeds a machine-specific maximum size, you get an
               error message from the linker indicating that -fpic does not work;
               in that case, recompile with -fPIC instead.  (These maximums are 8k
               on the SPARC and 32k on the m68k and RS/6000.  The 386 has no such
               limit.)
    
               Position-independent code requires special support, and therefore
               works only on certain machines.  For the 386, GCC supports PIC for
               System V but not for the Sun 386i.  Code generated for the IBM
               RS/6000 is always position-independent.
    
               When this flag is set, the macros "__pic__" and "__PIC__" are
               defined to 1.
    
           -fPIC
               If supported for the target machine, emit position-independent
               code, suitable for dynamic linking and avoiding any limit on the
               during linking.
    
               -fpie and -fPIE both define the macros "__pie__" and "__PIE__".
               The macros have the value 1 for -fpie and 2 for -fPIE.
    
           -fno-jump-tables
               Do not use jump tables for switch statements even where it would be
               more efficient than other code generation strategies.  This option
               is of use in conjunction with -fpic or -fPIC for building code
               which forms part of a dynamic linker and cannot reference the
               address of a jump table.  On some targets, jump tables do not
               require a GOT and this option is not needed.
    
           -ffixed-reg
               Treat the register named reg as a fixed register; generated code
               should never refer to it (except perhaps as a stack pointer, frame
               pointer or in some other fixed role).
    
               reg must be the name of a register.  The register names accepted
               are machine-specific and are defined in the "REGISTER_NAMES" macro
               in the machine description macro file.
    
               This flag does not have a negative form, because it specifies a
               three-way choice.
    
           -fcall-used-reg
               Treat the register named reg as an allocable register that is
               clobbered by function calls.  It may be allocated for temporaries
               or variables that do not live across a call.  Functions compiled
               this way will not save and restore the register reg.
    
               It is an error to used this flag with the frame pointer or stack
               pointer.  Use of this flag for other registers that have fixed
               pervasive roles in the machine's execution model will produce
               disastrous results.
    
               This flag does not have a negative form, because it specifies a
               three-way choice.
    
           -fcall-saved-reg
               Treat the register named reg as an allocable register saved by
               functions.  It may be allocated even for temporaries or variables
               that live across a call.  Functions compiled this way will save and
               restore the register reg if they use it.
    
               It is an error to used this flag with the frame pointer or stack
               pointer.  Use of this flag for other registers that have fixed
               pervasive roles in the machine's execution model will produce
               disastrous results.
    
               A different sort of disaster will result from the use of this flag
               for a register in which function values may be returned.
               Additionally, it makes the code suboptimal.  Use it to conform to a
               non-default application binary interface.
    
           -finstrument-functions
               Generate instrumentation calls for entry and exit to functions.
               Just after function entry and just before function exit, the
               following profiling functions will be called with the address of
               the current function and its call site.  (On some platforms,
               "__builtin_return_address" does not work beyond the current
               function, so the call site information may not be available to the
               profiling functions otherwise.)
    
                       void __cyg_profile_func_enter (void *this_fn,
                                                      void *call_site);
                       void __cyg_profile_func_exit  (void *this_fn,
                                                      void *call_site);
    
               The first argument is the address of the start of the current
               function, which may be looked up exactly in the symbol table.
    
               This instrumentation is also done for functions expanded inline in
               other functions.  The profiling calls will indicate where,
               conceptually, the inline function is entered and exited.  This
               means that addressable versions of such functions must be
               available.  If all your uses of a function are expanded inline,
               this may mean an additional expansion of code size.  If you use
               extern inline in your C code, an addressable version of such
               functions must be provided.  (This is normally the case anyways,
               but if you get lucky and the optimizer always expands the functions
               inline, you might have gotten away without providing static
               copies.)
    
               A function may be given the attribute "no_instrument_function", in
               which case this instrumentation will not be done.  This can be
               used, for example, for the profiling functions listed above, high-
               priority interrupt routines, and any functions from which the
               profiling functions cannot safely be called (perhaps signal
               handlers, if the profiling routines generate output or allocate
               memory).
    
           -finstrument-functions-exclude-file-list=file,file,...
               Set the list of functions that are excluded from instrumentation
               (see the description of "-finstrument-functions").  If the file
               that contains a function definition matches with one of file, then
               that function is not instrumented.  The match is done on
               substrings: if the file parameter is a substring of the file name,
               it is considered to be a match.
    
               For example,
               "-finstrument-functions-exclude-file-list=/bits/stl,include/sys"
               will exclude any inline function defined in files whose pathnames
               contain "/bits/stl" or "include/sys".
    
           -fstack-check
               Generate code to verify that you do not go beyond the boundary of
               the stack.  You should specify this flag if you are running in an
               environment with multiple threads, but only rarely need to specify
               it in a single-threaded environment since stack overflow is
               automatically detected on nearly all systems if there is only one
               stack.
    
               Note that this switch does not actually cause checking to be done;
               the operating system or the language runtime must do that.  The
               switch causes generation of code to ensure that they see the stack
               being extended.
    
               You can additionally specify a string parameter: "no" means no
               checking, "generic" means force the use of old-style checking,
               "specific" means use the best checking method and is equivalent to
               bare -fstack-check.
    
               Old-style checking is a generic mechanism that requires no specific
               target support in the compiler but comes with the following
               drawbacks:
    
               1.  Modified allocation strategy for large objects: they will
                   always be allocated dynamically if their size exceeds a fixed
                   threshold.
    
               2.  Fixed limit on the size of the static frame of functions: when
                   it is topped by a particular function, stack checking is not
                   reliable and a warning is issued by the compiler.
    
               3.  Inefficiency: because of both the modified allocation strategy
                   and the generic implementation, the performances of the code
                   are hampered.
    
               Note that old-style stack checking is also the fallback method for
               "specific" if no target support has been added in the compiler.
    
           -fstack-limit-register=reg
           -fstack-limit-symbol=sym
           -fno-stack-limit
               Generate code to ensure that the stack does not grow beyond a
               certain value, either the value of a register or the address of a
               symbol.  If the stack would grow beyond the value, a signal is
               raised.  For most targets, the signal is raised before the stack
               overruns the boundary, so it is possible to catch the signal
               without taking special precautions.
    
               For instance, if the stack starts at absolute address 0x80000000
               and grows downwards, you can use the flags
               -fstack-limit-symbol=__stack_limit and
               -Wl,--defsym,__stack_limit=0x7ffe0000 to enforce a stack limit of
               -fargument-noalias-anything specifies that arguments do not alias
               any other storage.
    
               Each language will automatically use whatever option is required by
               the language standard.  You should not need to use these options
               yourself.
    
           -fleading-underscore
               This option and its counterpart, -fno-leading-underscore, forcibly
               change the way C symbols are represented in the object file.  One
               use is to help link with legacy assembly code.
    
               Warning: the -fleading-underscore switch causes GCC to generate
               code that is not binary compatible with code generated without that
               switch.  Use it to conform to a non-default application binary
               interface.  Not all targets provide complete support for this
               switch.
    
           -ftls-model=model
               Alter the thread-local storage model to be used.  The model
               argument should be one of "global-dynamic", "local-dynamic",
               "initial-exec" or "local-exec".
    
               The default without -fpic is "initial-exec"; with -fpic the default
               is "global-dynamic".
    
           -fvisibility=default|internal|hidden|protected
               Set the default ELF image symbol visibility to the specified
               option---all symbols will be marked with this unless overridden
               within the code.  Using this feature can very substantially improve
               linking and load times of shared object libraries, produce more
               optimized code, provide near-perfect API export and prevent symbol
               clashes.  It is strongly recommended that you use this in any
               shared objects you distribute.
    
               Despite the nomenclature, "default" always means public ie;
               available to be linked against from outside the shared object.
               "protected" and "internal" are pretty useless in real-world usage
               so the only other commonly used option will be "hidden".  The
               default if -fvisibility isn't specified is "default", i.e., make
               every symbol public---this causes the same behavior as previous
               versions of GCC.
    
               A good explanation of the benefits offered by ensuring ELF symbols
               have the correct visibility is given by "How To Write Shared
               Libraries" by Ulrich Drepper (which can be found at
               <http://people.redhat.com/~drepper/>)---however a superior solution
               made possible by this option to marking things hidden when the
               default is public is to make the default hidden and mark things
               public.  This is the norm with DLL's on Windows and with
               -fvisibility=hidden and "__attribute__ ((visibility("default")))"
               instead of "__declspec(dllexport)" you get almost identical
               and operator delete must always be of default visibility.
    
               Be aware that headers from outside your project, in particular
               system headers and headers from any other library you use, may not
               be expecting to be compiled with visibility other than the default.
               You may need to explicitly say #pragma GCC visibility push(default)
               before including any such headers.
    
               extern declarations are not affected by -fvisibility, so a lot of
               code can be recompiled with -fvisibility=hidden with no
               modifications.  However, this means that calls to extern functions
               with no explicit visibility will use the PLT, so it is more
               effective to use __attribute ((visibility)) and/or #pragma GCC
               visibility to tell the compiler which extern declarations should be
               treated as hidden.
    
               Note that -fvisibility does affect C++ vague linkage entities. This
               means that, for instance, an exception class that will be thrown
               between DSOs must be explicitly marked with default visibility so
               that the type_info nodes will be unified between the DSOs.
    
               An overview of these techniques, their benefits and how to use them
               is at <http://gcc.gnu.org/wiki/Visibility>.
    
    
    

    ENVIRONMENT

           This section describes several environment variables that affect how
           GCC operates.  Some of them work by specifying directories or prefixes
           to use when searching for various kinds of files.  Some are used to
           specify other aspects of the compilation environment.
    
           Note that you can also specify places to search using options such as
           -B, -I and -L.  These take precedence over places specified using
           environment variables, which in turn take precedence over those
           specified by the configuration of GCC.
    
           LANG
           LC_CTYPE
           LC_MESSAGES
           LC_ALL
               These environment variables control the way that GCC uses
               localization information that allow GCC to work with different
               national conventions.  GCC inspects the locale categories LC_CTYPE
               and LC_MESSAGES if it has been configured to do so.  These locale
               categories can be set to any value supported by your installation.
               A typical value is en_GB.UTF-8 for English in the United Kingdom
               encoded in UTF-8.
    
               The LC_CTYPE environment variable specifies character
               classification.  GCC uses it to determine the character boundaries
               in a string; this is needed for some multibyte encodings that
               contain quote and escape characters that would otherwise be
               interpreted as a string end or escape.
               example, the output of the preprocessor, which is the input to the
               compiler proper.
    
           GCC_EXEC_PREFIX
               If GCC_EXEC_PREFIX is set, it specifies a prefix to use in the
               names of the subprograms executed by the compiler.  No slash is
               added when this prefix is combined with the name of a subprogram,
               but you can specify a prefix that ends with a slash if you wish.
    
               If GCC_EXEC_PREFIX is not set, GCC will attempt to figure out an
               appropriate prefix to use based on the pathname it was invoked
               with.
    
               If GCC cannot find the subprogram using the specified prefix, it
               tries looking in the usual places for the subprogram.
    
               The default value of GCC_EXEC_PREFIX is prefix/lib/gcc/ where
               prefix is the prefix to the installed compiler. In many cases
               prefix is the value of "prefix" when you ran the configure script.
    
               Other prefixes specified with -B take precedence over this prefix.
    
               This prefix is also used for finding files such as crt0.o that are
               used for linking.
    
               In addition, the prefix is used in an unusual way in finding the
               directories to search for header files.  For each of the standard
               directories whose name normally begins with /usr/local/lib/gcc
               (more precisely, with the value of GCC_INCLUDE_DIR), GCC tries
               replacing that beginning with the specified prefix to produce an
               alternate directory name.  Thus, with -Bfoo/, GCC will search
               foo/bar where it would normally search /usr/local/lib/bar.  These
               alternate directories are searched first; the standard directories
               come next. If a standard directory begins with the configured
               prefix then the value of prefix is replaced by GCC_EXEC_PREFIX when
               looking for header files.
    
           COMPILER_PATH
               The value of COMPILER_PATH is a colon-separated list of
               directories, much like PATH.  GCC tries the directories thus
               specified when searching for subprograms, if it can't find the
               subprograms using GCC_EXEC_PREFIX.
    
           LIBRARY_PATH
               The value of LIBRARY_PATH is a colon-separated list of directories,
               much like PATH.  When configured as a native compiler, GCC tries
               the directories thus specified when searching for special linker
               files, if it can't find them using GCC_EXEC_PREFIX.  Linking using
               GCC also uses these directories when searching for ordinary
               libraries for the -l option (but directories specified with -L come
               first).
    
               C-EUCJP
                   Recognize EUCJP characters.
    
               If LANG is not defined, or if it has some other value, then the
               compiler will use mblen and mbtowc as defined by the default locale
               to recognize and translate multibyte characters.
    
           Some additional environments variables affect the behavior of the
           preprocessor.
    
           CPATH
           C_INCLUDE_PATH
           CPLUS_INCLUDE_PATH
           OBJC_INCLUDE_PATH
               Each variable's value is a list of directories separated by a
               special character, much like PATH, in which to look for header
               files.  The special character, "PATH_SEPARATOR", is target-
               dependent and determined at GCC build time.  For Microsoft Windows-
               based targets it is a semicolon, and for almost all other targets
               it is a colon.
    
               CPATH specifies a list of directories to be searched as if
               specified with -I, but after any paths given with -I options on the
               command line.  This environment variable is used regardless of
               which language is being preprocessed.
    
               The remaining environment variables apply only when preprocessing
               the particular language indicated.  Each specifies a list of
               directories to be searched as if specified with -isystem, but after
               any paths given with -isystem options on the command line.
    
               In all these variables, an empty element instructs the compiler to
               search its current working directory.  Empty elements can appear at
               the beginning or end of a path.  For instance, if the value of
               CPATH is ":/special/include", that has the same effect as
               -I. -I/special/include.
    
           DEPENDENCIES_OUTPUT
               If this variable is set, its value specifies how to output
               dependencies for Make based on the non-system header files
               processed by the compiler.  System header files are ignored in the
               dependency output.
    
               The value of DEPENDENCIES_OUTPUT can be just a file name, in which
               case the Make rules are written to that file, guessing the target
               name from the source file name.  Or the value can have the form
               file target, in which case the rules are written to file file using
               target as the target name.
    
               In other words, this environment variable is equivalent to
               combining the options -MM and -MF, with an optional -MT switch too.
    
               to supply the correct flags may lead to subtle defects.  Supplying
               them in cases where they are not necessary is innocuous.
    
    
    

    SEE ALSO

           gpl(7), gfdl(7), fsf-funding(7), cpp(1), gcov(1), as(1), ld(1), gdb(1),
           adb(1), dbx(1), sdb(1) and the Info entries for gcc, cpp, as, ld,
           binutils and gdb.
    
    
    

    AUTHOR

           See the Info entry for gcc, or
           <http://gcc.gnu.org/onlinedocs/gcc/Contributors.html>, for contributors
           to GCC.
    
    
    

    COPYRIGHT

           Copyright (c) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
           1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free
           Software Foundation, Inc.
    
           Permission is granted to copy, distribute and/or modify this document
           under the terms of the GNU Free Documentation License, Version 1.2 or
           any later version published by the Free Software Foundation; with the
           Invariant Sections being "GNU General Public License" and "Funding Free
           Software", the Front-Cover texts being (a) (see below), and with the
           Back-Cover Texts being (b) (see below).  A copy of the license is
           included in the gfdl(7) man page.
    
           (a) The FSF's Front-Cover Text is:
    
                A GNU Manual
    
           (b) The FSF's Back-Cover Text is:
    
                You have freedom to copy and modify this GNU Manual, like GNU
                software.  Copies published by the Free Software Foundation raise
                funds for GNU development.
    
    
    

    gcc-4.4.7 2012-03-13 GCC(1)

    
    
  • MORE RESOURCE


  • Linux

    The Distributions





    Linux

    The Software





    Linux

    The News



  • MARKETING






  • Toll Free

webmaster@linuxguruz.com
Copyright © 1999 - 2016 by LinuxGuruz