MAN page from SuSE Other gcc_41-c++-4.1.0_20060408_Release-1.gbv.suse93.i586.rpm

GCC

Section: GNU (1)
Updated: 2006-04-12
Index

NAME

gcc - GNU project C and C++ compiler

SYNOPSIS

gcc [-c|-S|-E] [-std=standard]
    [-g] [-pg] [-Olevel]
    [-Wwarn...] [-pedantic]
    [-Idir...] [-Ldir...]
    [-Dmacro[=defn]...] [-Umacro]
    [-foption...] [-mmachine-option...]
    [-o outfile] infile...

Only the most useful options are listed here; see below for theremainder. 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 thisprocess at an intermediate stage. For example, the -c optionsays not to run the linker. Then the output consists of object filesoutput by the assembler.

Other options are passed on to one stage of processing. Some optionscontrol the preprocessor and others the compiler itself. Yet otheroptions control the assembler and linker; most of these are notdocumented here, since you rarely need to use any of them.

Most of the command line options that you can use with GCC are usefulfor C programs; when an option is only useful with another language(usually C++), the explanation says so explicitly. If the descriptionfor a particular option does not mention a source language, you can usethat option with all supported languages.

The gcc program accepts options and file names as operands. Manyoptions have multi-letter names; therefore multiple single-letter optionsmay not be grouped: -dr is very different from -d -r.

You can mix options and other arguments. For the most part, the orderyou use doesn't matter. Order does matter when you use several optionsof the same kind; for example, if you specify -L more than once,the directories are searched in the order specified.

Many options have long names starting with -f or with-W---for example, -fstrength-reduce, -Wformat and so on. Most ofthese have both positive and negative forms; the negative form of-ffoo would be -fno-foo. This manual documentsonly 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 arein the following sections.

Overall Options

-c -S -E -o file -combine -pipe -pass-exit-codes -x language -v -### --help --target-help --version

C Language Options

-ansi -std=standard -aux-info filename -fno-asm -fno-builtin -fno-builtin-function -fhosted -ffreestanding -fms-extensions -trigraphs -no-integrated-cpp -traditional -traditional-cpp -fallow-single-precision -fcond-mismatch -fsigned-bitfields -fsigned-char -funsigned-bitfields -funsigned-char

C++ Language Options

-fabi-version=n -fno-access-control -fcheck-new -fconserve-space -ffriend-injection -fno-const-strings -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 -Wabi -Wctor-dtor-privacy -Wnon-virtual-dtor -Wreorder -Weffc++ -Wno-deprecated -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-options

Warning Options

-fsyntax-only -pedantic -pedantic-errors -w -Wextra -Wall -Waggregate-return -Wno-attributes -Wc++-compat -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment -Wconversion -Wno-deprecated-declarations -Wdisabled-optimization -Wno-div-by-zero -Wno-endif-labels -Werror -Werror-implicit-function-declaration -Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 -Wno-format-extra-args -Wformat-nonliteral -Wformat-security -Wformat-y2k -Wimplicit -Wimplicit-function-declaration -Wimplicit-int -Wimport -Wno-import -Winit-self -Winline -Wno-int-to-pointer-cast -Wno-invalid-offsetof -Winvalid-pch -Wlarger-than-len -Wunsafe-loop-optimizations -Wlong-long -Wmain -Wmissing-braces -Wmissing-field-initializers -Wmissing-format-attribute -Wmissing-include-dirs -Wmissing-noreturn -Wno-multichar -Wnonnull -Wpacked -Wpadded -Wparentheses -Wpointer-arith -Wno-pointer-to-int-cast -Wredundant-decls -Wreturn-type -Wsequence-point -Wshadow -Wsign-compare -Wstack-protector -Wstrict-aliasing -Wstrict-aliasing=2 -Wswitch -Wswitch-default -Wswitch-enum -Wsystem-headers -Wtrigraphs -Wundef -Wuninitialized -Wunknown-pragmas -Wno-pragmas -Wunreachable-code -Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value -Wunused-variable -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings

C-only Warning Options

-Wbad-function-cast -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wstrict-prototypes -Wtraditional -Wdeclaration-after-statement -Wpointer-sign

Debugging Options

-dletters -dumpspecs -dumpmachine -dumpversion -fdump-unnumbered -fdump-translation-unit[-n] -fdump-class-hierarchy[-n] -fdump-ipa-all -fdump-ipa-cgraph -fdump-tree-all -fdump-tree-original[-n] -fdump-tree-optimized[-n] -fdump-tree-inlined[-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-salias -fdump-tree-fre[-n] -fdump-tree-vrp[-n] -ftree-vectorizer-verbose=n -fdump-tree-storeccp[-n] -feliminate-dwarf2-dups -feliminate-unused-debug-types -feliminate-unused-debug-symbols -fmem-report -fprofile-arcs -frandom-seed=string -fsched-verbose=n -ftest-coverage -ftime-report -fvar-tracking -g -glevel -gcoff -gdwarf-2 -ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ -p -pg -print-file-name=library -print-libgcc-file-name -print-multi-directory -print-multi-lib -print-prog-name=program -print-search-dirs -Q -save-temps -time

Optimization Options

-falign-functions=n -falign-jumps=n -falign-labels=n -falign-loops=n -fbounds-check -fmudflap -fmudflapth -fmudflapir -fbranch-probabilities -fprofile-values -fvpt -fbranch-target-load-optimize -fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves -fcprop-registers -fcse-follow-jumps -fcse-skip-blocks -fcx-limited-range -fdata-sections -fdelayed-branch -fdelete-null-pointer-checks -fearly-inlining -fexpensive-optimizations -ffast-math -ffloat-store -fforce-addr -ffunction-sections -fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload -floop-optimize -fcrossjumping -fif-conversion -fif-conversion2 -finline-functions -finline-functions-called-once -finline-limit=n -fkeep-inline-functions -fkeep-static-consts -fmerge-constants -fmerge-all-constants -fmodulo-sched -fno-branch-count-reg -fno-default-inline -fno-defer-pop -floop-optimize2 -fmove-loop-invariants -fno-function-cse -fno-guess-branch-probability -fno-inline -fno-math-errno -fno-peephole -fno-peephole2 -funsafe-math-optimizations -funsafe-loop-optimizations -ffinite-math-only -fno-trapping-math -fno-zero-initialized-in-bss -fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls -fprefetch-loop-arrays -fprofile-generate -fprofile-use -fregmove -frename-registers -freorder-blocks -freorder-blocks-and-partition -freorder-functions -frerun-cse-after-loop -frerun-loop-opt -frounding-math -fschedule-insns -fschedule-insns2 -fno-sched-interblock -fno-sched-spec -fsched-spec-load -fsched-spec-load-dangerous -fsched-stalled-insns=n -fsched-stalled-insns-dep=n -fsched2-use-superblocks -fsched2-use-traces -freschedule-modulo-scheduled-loops -fsignaling-nans -fsingle-precision-constant -fstack-protector -fstack-protector-all -fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps -funroll-all-loops -funroll-loops -fpeel-loops -fsplit-ivs-in-unroller -funswitch-loops -fvariable-expansion-in-unroller -ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize -ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts -ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink -ftree-ch -ftree-sra -ftree-ter -ftree-lrs -ftree-fre -ftree-vectorize -ftree-vect-loop-version -ftree-salias -fweb -ftree-copy-prop -ftree-store-ccp -ftree-store-copy-prop -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 -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 -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 -mapcs-stack-check -mno-apcs-stack-check -mapcs-float -mno-apcs-float -mapcs-reentrant -mno-apcs-reentrant -msched-prolog -mno-sched-prolog -mlittle-endian -mbig-endian -mwords-little-endian -mfloat-abi=name -msoft-float -mhard-float -mfpe -mthumb-interwork -mno-thumb-interwork -mcpu=name -march=name -mfpu=name -mstructure-size-boundary=n -mabort-on-noreturn -mlong-calls -mno-long-calls -msingle-pic-base -mno-single-pic-base -mpic-register=reg -mnop-fun-dllimport -mcirrus-fix-invalid-insns -mno-cirrus-fix-invalid-insns -mpoke-function-name -mthumb -marm -mtpcs-frame -mtpcs-leaf-frame -mcaller-super-interworking -mcallee-super-interworking -mtp=name

AVR Options-mmcu=mcu -msize -minit-stack=n -mno-interrupts -mcall-prologues -mno-tablejump -mtiny-stack -mint8

Blackfin Options-momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer -mspecld-anomaly -mno-specld-anomaly -mcsync-anomaly -mno-csync-anomaly -mlow-64k -mno-low64k -mid-shared-library -mno-id-shared-library -mshared-library-id=n -mlong-calls -mno-long-calls

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 -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 -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

FRV Options-mgpr-32 -mgpr-64 -mfpr-32 -mfpr-64 -mhard-float -msoft-float -malloc-cc -mfixed-cc -mdword -mno-dword -mdouble -mno-double -mmedia -mno-media -mmuladd -mno-muladd -mfdpic -minline-plt -mgprel-ro -multilib-library-pic -mlinked-fp -mlong-calls -malign-labels -mlibrary-pic -macc-4 -macc-8 -mpack -mno-pack -mno-eflags -mcond-move -mno-cond-move -moptimize-membar -mno-optimize-membar -mscc -mno-scc -mcond-exec -mno-cond-exec -mvliw-branch -mno-vliw-branch -mmulti-cond-exec -mno-multi-cond-exec -mnested-cond-exec -mno-nested-cond-exec -mtomcat-stats -mTLS -mtls -mcpu=cpu

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 -msvr3-shlib -mno-wide-multiply -mrtd -malign-double -mpreferred-stack-boundary=num -mmmx -msse -msse2 -msse3 -m3dnow -mthreads -mno-align-stringops -minline-all-stringops -mpush-args -maccumulate-outgoing-args -m128bit-long-double -m96bit-long-double -mregparm=num -msseregparm -momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs -mcmodel=code-model -m32 -m64 -mlarge-data-threshold=num

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

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

M32C Options-mcpu=cpu -msim -memregs=number

M680x0 Options-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040 -m68060 -mcpu32 -m5200 -m68881 -mbitfield -mc68000 -mc68020 -mnobitfield -mrtd -mshort -msoft-float -mpcrel -malign-int -mstrict-align -msep-data -mno-sep-data -mshared-library-id=n -mid-shared-library -mno-id-shared-library

M68hc1x Options-m6811 -m6812 -m68hc11 -m68hc12 -m68hcs12 -mauto-incdec -minmax -mlong-calls -mshort -msoft-reg-count=count

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 -mips16 -mno-mips16 -mabi=abi -mabicalls -mno-abicalls -mxgot -mno-xgot -mgp32 -mgp64 -mfp32 -mfp64 -mhard-float -msoft-float -msingle-float -mdouble-float -mdsp -mpaired-single -mips3d -mlong64 -mlong32 -msym32 -mno-sym32 -Gnum -membedded-data -mno-embedded-data -muninit-const-in-rodata -mno-uninit-const-in-rodata -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-vr4120 -mno-fix-vr4120 -mfix-vr4130 -mfix-sb1 -mno-fix-sb1 -mflush-func=func -mno-flush-func -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

MT Options-mno-crt0 -mbacc -msim -march=cpu-type

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

PowerPC OptionsSee RS/6000 and PowerPC Options.

RS/6000 and PowerPC Options-mcpu=cpu-type -mtune=cpu-type -mpower -mno-power -mpower2 -mno-power2 -mpowerpc -mpowerpc64 -mno-powerpc -maltivec -mno-altivec -mpowerpc-gpopt -mno-powerpc-gpopt -mpowerpc-gfxopt -mno-powerpc-gfxopt -mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mfprnd -mno-fprnd -mnew-mnemonics -mold-mnemonics -mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc -m64 -m32 -mxl-compat -mno-xl-compat -mpe -malign-power -malign-natural -msoft-float -mhard-float -mmultiple -mno-multiple -mstring -mno-string -mupdate -mno-update -mfused-madd -mno-fused-madd -mbit-align -mno-bit-align -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 -mvrsave -mno-vrsave -mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double -mprototype -mno-prototype -msim -mmvme -mads -myellowknife -memb -msdata -msdata=opt -mvxworks -mwindiss -G num -pthread

S/390 and zSeries Options-mtune=cpu-type -march=cpu-type -mhard-float -msoft-float -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

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 -misize -mpadstruct -mspace -mprefergot -musermode -multcost=number -mdiv=strategy -mdivsi3_libfunc=name -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

System V Options-Qy -Qn -YP,paths -Ym,dir

TMS320C3x/C4x Options-mcpu=cpu -mbig -msmall -mregparm -mmemparm -mfast-fix -mmpyi -mbk -mti -mdp-isr-reload -mrpts=count -mrptb -mdb -mloop-unsigned -mparallel-insns -mparallel-mpy -mpreserve-float

V850 Options-mlong-calls -mno-long-calls -mep -mno-ep -mprolog-function -mno-prolog-function -mspace -mtda=n -msda=n -mzda=n -mapp-regs -mno-app-regs -mdisable-callt -mno-disable-callt -mv850e1 -mv850e -mv850 -mbig-switch

VAX Options-mg -mgnu -munix

x86-64 OptionsSee i386 and x86-64 Options.

Xstormy16 Options-msim

Xtensa Options-mconst16 -mno-const16 -mfused-madd -mno-fused-madd -mtext-section-literals -mno-text-section-literals -mtarget-align -mno-target-align -mlongcalls -mno-longcalls

zSeries OptionsSee 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 -fno-common -fno-ident -fpcc-struct-return -fpic -fPIC -fpie -fPIE -fno-jump-tables -freg-struct-return -fshared-data -fshort-enums -fshort-double -fshort-wchar -fverbose-asm -fpack-struct[=n] -fstack-check -fstack-limit-register=reg -fstack-limit-symbol=sym -fargument-alias -fargument-noalias -fargument-noalias-global -fleading-underscore -ftls-model=model -ftrapv -fwrapv -fbounds-check -fvisibility

Options Controlling the Kind of Output

Compilation can involve up to four stages: preprocessing, compilationproper, assembly and linking, always in that order. GCC is capable ofpreprocessing and compiling several files either into severalassembler input files, or into one assembler input file; then eachassembler input file produces an object file, and linking combines allthe 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 ofcompilation 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 libobjclibrary 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 libobjclibrary to make an Objective-C++ program work. Note that .M refersto a literal capital M.
file.mii: Objective-C++ source code which should not be preprocessed.
file.h: C, C++, Objective-C or Objective-C++ header file to be turned into aprecompiled header.
file.cc
file.cp
file.cxx
file.cpp
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: C++ header file to be turned into a precompiled header.
file.f
file.for
file.FOR: Fixed form Fortran source code which should not be preprocessed.
file.F
file.fpp
file.FPP: Fixed form Fortran source code which must be preprocessed (with the traditionalpreprocessor).
file.f90
file.f95: Free form Fortran source code which should not be preprocessed.
file.F90
file.F95: Free form Fortran source code which must be preprocessed (with thetraditional preprocessor).
file.ads: Ada source code file which contains a library unit declaration (adeclaration of a package, subprogram, or generic, or a genericinstantiation), or a library unit renaming declaration (a package,generic, or subprogram renaming declaration). Such files are alsocalled specs.
file.adb: Ada source code file containing a library unit body (a subprogram orpackage body). Such files are also called bodies.
file.s: Assembler code.
file.S: 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 filename suffix). This option applies to all following input files untilthe 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        treelang

-x none

Turn off any specification of a language, so that subsequent files arehandled according to their file name suffixes (as they are if -xhas not been used at all).

-pass-exit-codes

Normally the gcc program will exit with the code of 1 if anyphase of the compiler returns a non-success return code. If you specify-pass-exit-codes, the gcc program will instead return withnumerically highest error produced by any phase that returned an errorindication.

If you only want some of the stages of compilation, you can use-x (or filename suffixes) to tell gcc where to start, andone of the options -c, -S, or -E to say wheregcc 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 linkingstage simply is not done. The ultimate output is in the form of anobject file for each source file.

By default, the object file name for a source file is made by replacingthe suffix .c, .i, .s, etc., with .o.

Unrecognized input files, not requiring compilation or assembly, areignored.

-S

Stop after the stage of compilation proper; do not assemble. The outputis in the form of an assembler code file for each non-assembler inputfile specified.

By default, the assembler file name for a source file is made byreplacing the suffix .c, .i, etc., with .s.

Input files that don't require compilation are ignored.

-E

Stop after the preprocessing stage; do not run the compiler proper. Theoutput is in the form of preprocessed source code, which is sent to thestandard output.

Input files which don't require preprocessing are ignored.

-o file

Place output in file file. This applies regardless to whateversort 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 executablefile in a.out, the object file forsource.suffix in source.o, itsassembler file in source.s, a precompiled header file insource.suffix.gch, and all preprocessed C source onstandard output.

-v

Print (on standard error output) the commands executed to run the stagesof compilation. Also print the version number of the compiler driverprogram and of the preprocessor and the compiler proper.

-###

Like -v except the commands are not executed and all commandarguments are quoted. This is useful for shell scripts to capture thedriver-generated command lines.

-pipe

Use pipes rather than temporary files for communication between thevarious stages of compilation. This fails to work on some systems wherethe assembler is unable to read from a pipe; but the GNU assembler hasno trouble.

-combine

If you are compiling multiple source files, this option tells the driverto pass all the source files to the compiler at once (for thoselanguages for which the compiler can handle this). This will allowintermodule analysis (IMA) to be performed by the compiler. Currently the onlylanguage for which this is supported is C. If you pass source files formultiple languages to the driver, using this option, the driver will invokethe compiler(s) that support IMA once each, passing each compiler all thesource files appropriate for it. For those languages that do not supportIMA this option will be ignored, and the compiler will be invoked once foreach source file in that language. If you use this option in conjunctionwith -save-temps, the compiler will generate multiplepre-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 optionsunderstood by gcc. If the -v option is also specifiedthen --help will also be passed on to the various processesinvoked by gcc, so that they can display the command line optionsthey accept. If the -Wextra option is also specified then commandline options which have no documentation associated with them will alsobe displayed.

--target-help

Print (on the standard output) a description of target specific commandline options for each tool.

--version

Display the version number and copyrights of the invoked GCC.

Compiling C++ Programs

C++ source files conventionally use one of the suffixes .C,.cc, .cpp, .CPP, .c++, .cp, or.cxx; C++ header files often use .hh or .H; andpreprocessed C++ files use the suffix .ii. GCC recognizesfiles with these names and compiles them as C++ programs even if youcall the compiler the same way as for compiling C programs (usuallywith the name gcc).

However, C++ programs often require class libraries as well as acompiler that understands the C++ language---and under somecircumstances, you might want to compile programs or header files fromstandard input, or otherwise without a suffix that flags them as C++programs. You might also like to precompile a C header file with a.h extension to be used in C++ compilations. g++ is aprogram that calls GCC with the default language set to C++, andautomatically specifies linking against the C++ library. On manysystems, g++ is also installed with the name c++.

When you compile C++ programs, you may specify many of the samecommand-line options that you use for compiling programs in anylanguage; or command-line options meaningful for C and relatedlanguages; or options that are meaningful only for C++ programs.

Options Controlling C Dialect

The following options control the dialect of C (or languages derivedfrom C, such as C++, Objective-C and Objective-C++) that the compileraccepts:

-ansi

In C mode, support all ISO C90 programs. In C++ mode,remove GNU extensions that conflict with ISO C++.

This turns off certain features of GCC that are incompatible with ISOC90 (when compiling C code), or of standard C++ (when compiling C++ code),such as the "asm" and "typeof" keywords, andpredefined macros such as "unix" and "vax" that identify thetype of system you are using. It also enables the undesirable andrarely used ISO trigraph feature. For the C compiler,it disables recognition of C++ style // comments as well asthe "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, ofcourse, but it is useful to put them in header files that might be includedin compilations done with -ansi. Alternate predefined macrossuch as "__unix__" and "__vax__" are also available, with orwithout -ansi.

The -ansi option does not cause non-ISO programs to berejected gratuitously. For that, -pedantic is required inaddition to -ansi.

The macro "__STRICT_ANSI__" is predefined when the -ansioption is used. Some header files may notice this macro and refrainfrom declaring certain functions or defining certain macros that theISO standard doesn't call for; this is to avoid interfering with anyprograms that might use these names for other things.

Functions which would normally be built in but do not have semanticsdefined by ISO C (such as "alloca" and "ffs") are not built-infunctions with -ansi is used.

-std=

Determine the language standard. This option is currently onlysupported when compiling C or C++. A value for this option must beprovided; possible values are

c89
iso9899:1990: ISO C90 (same as -ansi).
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-4.1/c99status.html> for more information. Thenames c9x and iso9899:199x are deprecated.
gnu89: Default, ISO C90 plus GNU extensions (including some C99 features).
gnu99
gnu9x: ISO C99 plus GNU extensions. 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.
gnu++98: The same as -std=c++98 plus GNU extensions. This is thedefault for C++ code.

Even when this option is not specified, you can still use some of thefeatures of newer standards in so far as they do not conflict withprevious C standards. For example, you may use "__restrict__" evenwhen -std=c99 is not specified.

The -std options specifying some version of ISO C have the sameeffects as -ansi, except that features that were not in ISO C90but are in the specified version (for example, // comments andthe "inline" keyword in ISO C99) are not disabled.

-aux-info filename

Output to the given filename prototyped declarations for all functionsdeclared and/or defined in a translation unit, including those in headerfiles. This option is silently ignored in any language other than C.

Besides declarations, the file indicates, in comments, the origin ofeach declaration (source file and line), whether the declaration wasimplicit, prototyped or unprototyped (I, N for new orO for old, respectively, in the first character after the linenumber and the colon), and whether it came from a declaration or adefinition (C or F, respectively, in the followingcharacter). In the case of function definitions, a K&R-style list ofarguments followed by their declarations is also provided, insidecomments, after the declaration.

-fno-asm

Do not recognize "asm", "inline" or "typeof" as akeyword, so that code can use these words as identifiers. You can usethe 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 touse the -fno-gnu-keywords flag instead, which has the sameeffect. In C99 mode (-std=c99 or -std=gnu99), thisswitch 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 functionsmore efficiently; for instance, calls to "alloca" may become singleinstructions that adjust the stack directly, and calls to "memcpy"may become inline copy loops. The resulting code is often both smallerand faster, but since the function calls no longer appear as such, youcannot set a breakpoint on those calls, nor can you change the behaviorof the functions by linking with a different library. In addition,when a function is recognized as a built-in function, GCC may useinformation about that function to warn about problems with calls tothat function, or to generate more efficient code, even if theresulting 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" isknown not to modify global memory.

With the -fno-builtin-function optiononly the built-in function function isdisabled. function must not begin with __builtin_. If afunction is named this is not built-in in this version of GCC, thisoption is ignored. There is no corresponding-fbuiltin-function option; if you wish to enablebuilt-in functions selectively when using -fno-builtin or-ffreestanding, you may define macros such as:

        #define abs(n)          __builtin_abs ((n))        #define strcpy(d, s)    __builtin_strcpy ((d), (s))

-fhosted

Assert that compilation takes place in a hosted environment. This implies-fbuiltin. A hosted environment is one in which theentire standard library is available, and in which "main" has a returntype of "int". Examples are nearly everything except a kernel.This is equivalent to -fno-freestanding.

-ffreestanding

Assert that compilation takes place in a freestanding environment. Thisimplies -fno-builtin. A freestanding environmentis one in which the standard library may not exist, and program startup maynot necessarily be at "main". The most obvious example is an OS kernel.This is equivalent to -fno-hosted.

-fms-extensions

Accept some non-standard constructs used in Microsoft header files.

Some cases of unnamed fields in structures and unions are onlyaccepted with this option.

-trigraphs

Support ISO C trigraphs. The -ansi option (and -stdoptions for strict ISO C conformance) implies -trigraphs.

-no-integrated-cpp

Performs a compilation in two passes: preprocessing and compiling. Thisoption allows a user supplied ``cc1'', ``cc1plus'', or ``cc1obj'' via the-B option. The user supplied compilation step can then add inan additional preprocessing step after normal preprocessing but beforecompiling. 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-standardC compiler. They are now only supported with the -E switch.The preprocessor continues to support a pre-standard mode. See the GNUCPP manual for details.

-fcond-mismatch

Allow conditional expressions with mismatched types in the second andthird arguments. The value of such an expression is void. This optionis not supported for C++.

-funsigned-char

Let the type "char" be unsigned, like "unsigned char".

Each kind of machine has a default for what "char" shouldbe. It is either like "unsigned char" by default or like"signed char" by default.

Ideally, a portable program should always use "signed char" or"unsigned char" when it depends on the signedness of an object.But many programs have been written to use plain "char" andexpect it to be signed, or expect it to be unsigned, depending on themachines they were written for. This option, and its inverse, let youmake such a program work with the opposite default.

The type "char" is always a distinct type from each of"signed char" or "unsigned char", even though its behavioris 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 isthe 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 thedeclaration does not use either "signed" or "unsigned". Bydefault, such a bit-field is signed, because this is consistent: thebasic integer types such as "int" are signed types.

Options Controlling C++ Dialect

This section describes the command-line options that are only meaningfulfor C++ programs; but you can also use most of the GNU compiler optionsregardless of what language your program is in. For example, youmight compile a file "firstClass.C" like this:

        g++ -g -frepo -O -c firstClass.C

In this example, only -frepo is an option meantonly for C++ programs; you can use the other options with anylanguage 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 theC++ ABI that first appeared in G++ 3.4. Version 1 is the version ofthe C++ ABI that first appeared in G++ 3.2. Version 0 will always bethe version that conforms most closely to the C++ ABI specification.Therefore, the ABI obtained using version 0 will change as ABI bugsare fixed.
The default is version 2.
-fno-access-control: Turn off all access checking. This switch is mainly useful for workingaround bugs in the access control code.
-fcheck-new: Check that the pointer returned by "operator new" is non-nullbefore attempting to modify the storage allocated. This check isnormally unnecessary because the C++ standard specifies that"operator new" will only return 0 if it is declaredthrow(), in which case the compiler will always check thereturn value even without this option. In all other cases, when"operator new" has a non-empty exception specification, memoryexhaustion is signalled by throwing "std::bad_alloc". See alsonew (nothrow).
-fconserve-space: Put uninitialized or runtime-initialized global variables into thecommon segment, as C does. This saves space in the executable at thecost of not diagnosing duplicate definitions. If you compile with thisflag and your program mysteriously crashes after "main()" hascompleted, you may have an object that is being destroyed twice becausetwo definitions were merged.
This option is no longer useful on most targets, now that support hasbeen added for putting variables into BSS without making them common.
-ffriend-injection: Inject friend functions into the enclosing namespace, so that they arevisible outside the scope of the class in which they are declared.Friend functions were documented to work this way in the old AnnotatedC++ Reference Manual, and versions of G++ before 4.1 always workedthat way. However, in ISO C++ a friend function which is not declaredin an enclosing scope can only be found using argument dependentlookup. This option causes friends to be injected as they were inearlier releases.
This option is for compatibility, and may be removed in a futurerelease of G++.
-fno-const-strings: Give string constants type "char *" instead of type "constchar *". By default, G++ uses type "const char *" as required bythe standard. Even if you use -fno-const-strings, you cannotactually modify the value of a string constant.
This option might be removed in a future release of G++. For maximumportability, you should structure your code so that it works withstring constants that have type "const char *".
-fno-elide-constructors: The C++ standard allows an implementation to omit creating a temporarywhich is only used to initialize another object of the same type.Specifying this option disables that optimization, and forces G++ tocall the copy constructor in all cases.
-fno-enforce-eh-specs: Don't generate code to check for violation of exception specificationsat runtime. This option violates the C++ standard, but may be usefulfor reducing code size in production builds, much like definingNDEBUG. This does not give user code permission to throwexceptions in violation of the exception specifications; the compilerwill still optimize based on the specifications, so throwing anunexpected exception will result in undefined behavior.
-ffor-scope
-fno-for-scope: If -ffor-scope is specified, the scope of variables declared ina for-init-statement is limited to the for loop itself,as specified by the C++ standard.If -fno-for-scope is specified, the scope of variables declared ina for-init-statement extends to the end of the enclosing scope,as was the case in old versions of G++, and other (traditional)implementations of C++.
The default if neither flag is given to follow the standard,but to allow and give a warning for old-style code that wouldotherwise be invalid, or have different behavior.
-fno-gnu-keywords: Do not recognize "typeof" as a keyword, so that code can use thisword as an identifier. You can use the keyword "__typeof__" instead.-ansi implies -fno-gnu-keywords.
-fno-implicit-templates: Never emit code for non-inline templates which are instantiatedimplicitly (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 andwithout optimization will need the same set of explicit instantiations.
-fno-implement-inlines: To save space, do not emit out-of-line copies of inline functionscontrolled by #pragma implementation. This will cause linkererrors if these functions are not inlined everywhere they are called.
-fms-extensions: Disable pedantic warnings about constructs used in MFC, such as implicitint and getting a pointer to member function via non-standard syntax.
-fno-nonansi-builtins: Disable built-in declarations of functions that are not mandated byANSI/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" assynonyms as keywords.
-fno-optional-diags: Disable diagnostics that the standard says a compiler does not need toissue. Currently, the only such diagnostic issued by G++ is the one fora name having multiple meanings within a class.
-fpermissive: Downgrade some diagnostics about nonconformant code from errors towarnings. Thus, using -fpermissive will allow somenonconforming code to compile.
-frepo: Enable automatic template instantiation at link time. This option alsoimplies -fno-implicit-templates.
-fno-rtti: Disable generation of information about every class with virtualfunctions for use by the C++ runtime type identification features(dynamic_cast and typeid). If you don't use those partsof the language, you can save some space by using this flag. Note thatexception handling uses the same information, but it will generate it asneeded.
-fstats: Emit statistics about front-end processing at the end of the compilation.This information is generally only useful to the G++ development team.
-ftemplate-depth-n: Set the maximum instantiation depth for template classes to n.A limit on the template instantiation depth is needed to detectendless 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 thisoption to reduce code size slightly in code that doesn't need to bethread-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 staticdestructors, but will only work if your C library supports"__cxa_atexit".
-fvisibility-inlines-hidden: Causes all inlined methods to be marked with"__attribute__ ((visibility ("hidden")))" so that they do notappear in the export table of a DSO and do not require a PLT indirectionwhen used within the DSO. Enabling this option can have a dramatic effecton load and link times of a DSO as it massively reduces the size of thedynamic export table when the library makes heavy use of templates. Whileit can cause bloating through duplication of code within each DSO whereit is used, often the wastage is less than the considerable space occupiedby a long symbol name in the export table which is typical when usingtemplates and namespaces. For even more savings, combine with the-fvisibility=hidden switch.
-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. Thisoption exists only for testing, and should not be used by end-users;it will result in inferior code and has no benefits. This option maybe removed in a future release of G++.
-nostdinc++: Do not search for header files in the standard directories specific toC++, but do still search the other standard directories. (This optionis used when building the C++ library.)

In addition, these optimization, warning, and code generation optionshave meanings only for C++ programs:

-fno-default-inline: Do not assume inline for functions defined inside a class scope.
Note that thesefunctions will have linkage like inline func