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 the remainder.  g++ accepts mostly the same options as
       gcc.


DESCRIPTION

       When you invoke GCC, it normally does preprocessing, com­
       pilation, 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 com­
       piler 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: -dr is
       very different from -d -r.

       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 exam­
       ple, 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, -fforce-mem, -fstrength-reduce, -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.

           -traditional-cpp -fallow-single-precision  -fcond-mis­
           match -fsigned-bitfields  -fsigned-char -fun­
           signed-bitfields  -funsigned-char -fwritable-strings

       C++ Language Options
           -fabi-version=n -fno-access-control  -fcheck-new
           -fconserve-space -fno-const-strings  -fdol­
           lars-in-identifiers -fno-elide-constructors
           -fno-enforce-eh-specs  -fexternal-templates
           -falt-external-templates -ffor-scope  -fno-for-scope
           -fno-gnu-keywords -fno-implicit-templates
           -fno-implicit-inline-templates -fno-implement-inlines
           -fms-extensions -fno-nonansi-builtins  -fno-opera­
           tor-names -fno-optional-diags  -fpermissive -frepo
           -fno-rtti  -fstats  -ftemplate-depth-n
           -fuse-cxa-atexit  -fvtable-gc  -fno-weak  -nostdinc++
           -fno-default-inline -Wabi -Wctor-dtor-privacy
           -Wnon-virtual-dtor  -Wreorder -Weffc++  -Wno-depre­
           cated -Wno-non-template-friend  -Wold-style-cast
           -Woverloaded-virtual  -Wno-pmf-conversions
           -Wsign-promo  -Wsynth

       Objective-C Language Options
           -fconstant-string-class=class-name -fgnu-runtime
           -fnext-runtime  -gen-decls -Wno-protocol  -Wselector
           -Wundeclared-selector

       Language Independent Options
           -fmessage-length=n -fdiagnostics-show-loca­
           tion=[once|every-line]

       Warning Options
           -fsyntax-only  -pedantic  -pedantic-errors -w  -W
           -Wall -Waggregate-return -Wcast-align  -Wcast-qual
           -Wchar-subscripts  -Wcomment -Wconversion  -Wno-depre­
           cated-declarations -Wdisabled-optimization
           -Wno-div-by-zero  -Werror -Wfloat-equal  -Wformat
           -Wformat=2 -Wformat-nonliteral  -Wformat-security
           -Wimplicit  -Wimplicit-int -Wimplicit-function-decla­
           ration -Werror-implicit-function-declaration -Wimport
           -Winline -Wno-endif-labels -Wlarger-than-len
           -Wlong-long -Wmain  -Wmissing-braces -Wmissing-for­
           mat-attribute  -Wmissing-noreturn -Wno-multichar
           -Wno-format-extra-args  -Wno-format-y2k -Wno-import
           -Wnonnull  -Wpacked  -Wpadded -Wparentheses
           -Wpointer-arith  -Wredundant-decls -Wreturn-type
           -Wsequence-point  -Wshadow -Wsign-compare
           -Wstrict-aliasing -Wswitch  -Wswitch-default
           -Wswitch-enum -Wsystem-headers -Wtrigraphs  -Wundef
           -Wuninitialized -Wunknown-pragmas  -Wunreachable-code
           -Wunused  -Wunused-function  -Wunused-label
           -Wunused-parameter -Wunused-value  -Wunused-variable
           -glevel  -gcoff  -gdwarf  -gdwarf-1  -gdwarf-1+
           -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 -fbranch-probabilities  -fcaller-saves
           -fcprop-registers -fcse-follow-jumps
           -fcse-skip-blocks  -fdata-sections -fdelayed-branch
           -fdelete-null-pointer-checks -fexpensive-optimizations
           -ffast-math  -ffloat-store -fforce-addr  -fforce-mem
           -ffunction-sections -fgcse  -fgcse-lm  -fgcse-sm
           -floop-optimize -fcrossjumping -fif-conversion
           -fif-conversion2 -finline-functions  -finline-limit=n
           -fkeep-inline-functions -fkeep-static-consts
           -fmerge-constants  -fmerge-all-constants
           -fmove-all-movables  -fnew-ra  -fno-branch-count-reg
           -fno-default-inline  -fno-defer-pop -fno-function-cse
           -fno-guess-branch-probability -fno-inline
           -fno-math-errno  -fno-peephole  -fno-peephole2 -fun­
           safe-math-optimizations -ffinite-math-only -fno-trap­
           ping-math -fno-zero-initialized-in-bss
           -fomit-frame-pointer  -foptimize-register-move -fopti­
           mize-sibling-calls  -fprefetch-loop-arrays -fre­
           duce-all-givs -fregmove  -frename-registers -fre­
           order-blocks -freorder-functions -fre­
           run-cse-after-loop  -frerun-loop-opt -fschedule-insns
           -fschedule-insns2 -fno-sched-interblock
           -fno-sched-spec  -fsched-spec-load
           -fsched-spec-load-dangerous  -fsignaling-nans -fsin­
           gle-precision-constant  -fssa -fssa-ccp -fssa-dce
           -fstrength-reduce  -fstrict-aliasing  -ftracer
           -fthread-jumps -funroll-all-loops  -funroll-loops
           -fweb --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  -iwithpre­
           fix dir -iwithprefixbefore dir  -isystem dir -M  -MM
           -MF  -MG  -MP  -MQ  -MT  -nostdinc  -P  -remap -tri­
           graphs  -undef  -Umacro  -Wp,option

       Assembler Option
           -Wa,option

       Linker Options
            object-file-name  -llibrary -nostartfiles  -node­
           faultlibs  -nostdlib -s  -static  -static-libgcc
           -mc68000  -mc68020 -mfpa  -mnobitfield  -mrtd  -mshort
           -msoft-float  -mpcrel -malign-int  -mstrict-align

           M68hc1x Options

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

           VAX Options

           -mg  -mgnu  -munix

           SPARC Options

           -mcpu=cpu-type -mtune=cpu-type -mcmodel=code-model
           -m32  -m64 -mapp-regs  -mbroken-saverestore  -mcypress
           -mfaster-structs  -mflat -mfpu  -mhard-float
           -mhard-quad-float -mimpure-text  -mlive-g0
           -mno-app-regs -mno-faster-structs  -mno-flat  -mno-fpu
           -mno-impure-text  -mno-stack-bias  -mno-unaligned-dou­
           bles -msoft-float  -msoft-quad-float  -msparclite
           -mstack-bias -msupersparc  -munaligned-doubles  -mv8

           ARM Options

           -mapcs-frame  -mno-apcs-frame -mapcs-26  -mapcs-32
           -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 -malignment-traps
           -mno-alignment-traps -msoft-float  -mhard-float  -mfpe
           -mthumb-interwork  -mno-thumb-interwork -mcpu=name
           -march=name  -mfpe=name -mstructure-size-boundary=n
           -mabort-on-noreturn -mlong-calls  -mno-long-calls
           -msingle-pic-base  -mno-single-pic-base -mpic-regis­
           ter=reg -mnop-fun-dllimport -mpoke-function-name
           -mthumb  -marm -mtpcs-frame  -mtpcs-leaf-frame
           -mcaller-super-interworking  -mcallee-super-interwork­
           ing

           MN10200 Options

           -mrelax

           MN10300 Options

           -mmult-bug  -mno-mult-bug -mam33  -mno-am33 -mno-crt0
           -mrelax

           M32R/D Options

           -mwarn-passed-structs

           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-gfx­
           opt -mnew-mnemonics  -mold-mnemonics -mfull-toc
           -mminimal-toc  -mno-fp-in-toc  -mno-sum-in-toc -m64
           -m32  -mxl-call  -mno-xl-call  -mpe -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-relocat­
           able-lib -mtoc  -mno-toc -mlittle  -mlittle-endian
           -mbig  -mbig-endian -mcall-aix -mcall-sysv
           -mcall-netbsd -maix-struct-return -msvr4-struct-return
           -mabi=altivec -mabi=no-altivec -mabi=spe -mabi=no-spe
           -misel=yes -misel=no -mprototype  -mno-prototype -msim
           -mmvme  -mads  -myellowknife  -memb -msdata
           -msdata=opt  -mvxworks -mwindiss -G num -pthread

           Darwin Options

           -all_load -allowable_client -arch -arch_errors_fatal
           -arch_only -bind_at_load -bundle -bundle_loader
           -client_name -compatibility_version -current_version
           -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 -multi­
           ply_defined_unused -noall_load -nomultidefs -noprebind
           -noseglinkedit -pagezero_size -prebind -pre­
           bind_all_twolevel_modules -private_bundle
           -read_only_relocs -sectalign -sectobjectsymbols -why­
           load -seg1addr -sectcreate -sectobjectsymbols -sec­
           torder -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

           RT Options

           -mcall-lib-mul  -mfp-arg-in-fpregs  -mfp-arg-in-gregs
           -mfull-fp-blocks  -mhc-struct-return  -min-line-mul
           -mminimum-fp-blocks  -mnohc-struct-return
           -mstats  -EL  -EB  -G num  -nocpp -mabi=32  -mabi=n32
           -mabi=64  -mabi=eabi -mfix7000  -mno-crt0
           -mflush-func=func -mno-flush-func -mbranch-likely
           -mno-branch-likely

           i386 and x86-64 Options

           -mcpu=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 -m3dnow -mthreads  -mno-align-stringops
           -minline-all-stringops -mpush-args  -maccumulate-out­
           going-args  -m128bit-long-double -m96bit-long-double
           -mregparm=num  -momit-leaf-frame-pointer -mno-red-zone
           -mcmodel=code-model -m32 -m64

           HPPA Options

           -march=architecture-type -mbig-switch  -mdis­
           able-fpregs  -mdisable-indexing -mfast-indirect-calls
           -mgas  -mgnu-ld -mhp-ld -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

           Intel 960 Options

           -mcpu-type  -masm-compat  -mclean-linkage -mcode-align
           -mcomplex-addr  -mleaf-procedures -mic-compat
           -mic2.0-compat  -mic3.0-compat -mintel-asm
           -mno-clean-linkage  -mno-code-align -mno-complex-addr
           -mno-leaf-procedures -mno-old-align  -mno-strict-align
           -mno-tail-call -mnumerics  -mold-align  -msoft-float
           -mstrict-align -mtail-call

           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 -mmemory-latency=time

           DEC Alpha/VMS Options
           -mpadstruct  -mspace -mprefergot  -musermode

           System V Options

           -Qy  -Qn  -YP,paths  -Ym,dir

           ARC Options

           -EB  -EL -mmangle-cpu  -mcpu=cpu  -mtext=text-section
           -mdata=data-section  -mrodata=readonly-data-section

           TMS320C3x/C4x Options

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

           V850 Options

           -mlong-calls  -mno-long-calls  -mep  -mno-ep -mpro­
           log-function  -mno-prolog-function  -mspace -mtda=n
           -msda=n  -mzda=n -mapp-regs -mno-app-regs -mdis­
           able-callt -mno-disable-callt -mv850e -mv850
           -mbig-switch

           NS32K Options

           -m32032  -m32332  -m32532  -m32081  -m32381 -mmult-add
           -mnomult-add  -msoft-float  -mrtd  -mnortd -mregparam
           -mnoregparam  -msb  -mnosb -mbitfield  -mnobitfield
           -mhimem  -mnohimem

           AVR Options

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

           MCore Options

           -mhardlit  -mno-hardlit  -mdiv  -mno-div  -mre­
           lax-immediates -mno-relax-immediates  -mwide-bitfields
           -mno-wide-bitfields -m4byte-functions
           -mno-4byte-functions  -mcallgraph-data -mno-call­
           graph-data  -mslow-bytes  -mno-slow-bytes  -mno-lsim
           -mlittle-endian  -mbig-endian  -m210  -m340
           -mstack-increment

           MMIX Options

           -mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon
           -mabi=gnu -mabi=mmixware -mzero-extend -mknuthdiv

           D30V Options

           -mextmem  -mextmemory  -monchip  -mno-asm-optimize
           -masm-optimize -mbranch-cost=n -mcond-exec=n

           S/390 and zSeries Options

           -mhard-float  -msoft-float  -mbackchain
           -mno-backchain -msmall-exec  -mno-small-exec  -mmvcle
           -mno-mvcle -m64 -m31 -mdebug -mno-debug

           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-pro­
           logue-epilogue -mno-gotplt -melf -maout -melinux
           -mlinux -sim -sim2

           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

           Xstormy16 Options

           -msim

           Xtensa Options

           -mbig-endian -mlittle-endian -mdensity -mno-density
           -mmac16 -mno-mac16 -mmul16 -mno-mul16 -mmul32
           -mno-mul32 -mnsa -mno-nsa -mminmax -mno-minmax -msext
           -mno-sext -mbooleans -mno-booleans -mhard-float
           -msoft-float -mfused-madd -mno-fused-madd -mserial­
           ize-volatile -mno-serialize-volatile -mtext-sec­
           tion-literals -mno-text-section-literals -mtar­
           get-align -mno-target-align -mlongcalls -mno-longcalls

           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 -mlibrary-pic -macc-4 -macc-8 -mpack
           -mno-pack -mno-eflags -mcond-move -mno-cond-move -mscc
           -fpack-struct  -fstack-check -fstack-limit-regis­
           ter=reg  -fstack-limit-symbol=sym -fargument-alias
           -fargument-noalias -fargument-noalias-global  -flead­
           ing-underscore -ftls-model=model -ftrapv
           -fbounds-check

       Options Controlling the Kind of Output

       Compilation can involve up to four stages: preprocessing,
       compilation proper, assembly and linking, always in that
       order.  The first three stages apply to an individual
       source file, and end by producing an object file; 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 library libobjc.a to make an Objective-C program
           work.

       file.mi
           Objective-C source code which should not be prepro­
           cessed.

       file.h
           C header file (not to be compiled or linked).

       file.cc
       file.cp
       file.cxx
       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.f
       file.for
       file.FOR
           declaration (a declaration of a package, subprogram,
           or generic, or a generic instantiation), or a library
           unit renaming declaration (a package, generic, or sub­
           program renaming declaration).  Such files are also
           called specs.

       file.adb
           Ada source code file containing a library unit body (a
           subprogram or package 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 file name suffix).  This option
           applies to all following input files until the next -x
           option.  Possible values for language are:

                   c  c-header  cpp-output
                   c++  c++-cpp-output
                   objective-c  objc-cpp-output
                   assembler  assembler-with-cpp
                   ada
                   f77  f77-cpp-input  ratfor
                   java
                   treelang

       -x none
           Turn off any specification of a language, so that sub­
           sequent 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
           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 output is in the form of an assembler
           code file for each non-assembler input file specified.

           By default, the assembler file name for a source file
           is made by replacing 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.  The output is in the form of prepro­
           cessed source code, which is sent to the standard out­
           put.

           Input files which don't require preprocessing are
           ignored.

       -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.

           Since only one output file can be specified, it does
           not make sense to use -o when compiling more than one
           input file, unless you are producing an executable
           file as output.

           If -o is not specified, the default is to put an exe­
           cutable file in a.out, the object file for source.suf­
           fix in source.o, its assembler file in source.s, 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 ver­
           sion 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
           ated with them will also be displayed.

       --target-help
           Print (on the standard output) a description of target
           specific command line 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, .c++, .cp, or .cxx; preprocessed C++ files
       use the suffix .ii.  GCC recognizes files with these names
       and compiles them as C++ programs even if you call the
       compiler the same way as for compiling C programs (usually
       with the name gcc).

       However, C++ programs often require class libraries as
       well as a compiler that understands the C++ language---and
       under some circumstances, you might want to compile pro­
       grams from standard input, or otherwise without a suffix
       that flags them as C++ programs.  g++ is a program that
       calls GCC with the default language set to C++, and auto­
       matically specifies linking against the C++ library.  On
       many systems, g++ is also installed with the name c++.

       When you compile C++ programs, you may specify many of the
       same command-line options that you use for compiling pro­
       grams in any language; or command-line options meaningful
       for C and related languages; or options that are meaning­
       ful only for C++ programs.

       Options Controlling C Dialect

       The following options control the dialect of C (or lan­
       guages derived from C, such as C++ and Objective-C) that
       the compiler accepts:

       -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 incom­
           patible 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 com­
           piler, it disables recognition of C++ style // com­

           The macro "__STRICT_ANSI__" is predefined when the
           -ansi option is used.  Some header files may notice
           this macro and refrain from declaring certain func­
           tions 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 which would normally be built in but do not
           have semantics defined by ISO C (such as "alloca" and
           "ffs") are not built-in functions with -ansi is used.

       -std=
           Determine the language standard.  This option is cur­
           rently only supported when compiling C or C++.  A
           value for this option must be provided; possible val­
           ues 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-3.3/c99sta­
               tus.html> for more information.  The names 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 the default for C++ code.

           for all functions declared and/or defined in a trans­
           lation 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 declara­
           tions is also provided, inside comments, after the
           declaration.

       -fno-asm
           Do not recognize "asm", "inline" or "typeof" as a key­
           word, 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 key­
           word 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.

           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 this 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

       -ffreestanding
           Assert that compilation takes place in a freestanding
           environment.  This implies -fno-builtin.  A freestand­
           ing 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 ker­
           nel.  This is equivalent to -fno-hosted.

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

       -trigraphs
           Support ISO C trigraphs.  The -ansi option (and -std
           options for strict ISO C conformance) implies -tri­
           graphs.

       -traditional
       -traditional-cpp
           Formerly, these options caused GCC to attempt to emu­
           late a pre-standard C compiler.  They are now only
           supported with the -E switch.  The preprocessor con­
           tinues 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++.

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

           Each kind of machine has a default for what "char"
           should be.  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" and expect it to be
           signed, or expect it to be unsigned, depending on the
           machines they were written for.  This option, and its
           inverse, let you make 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
           behavior is always just like one of those two.

       -fsigned-char
           is signed, because this is consistent: the basic inte­
           ger types such as "int" are signed types.

       -fwritable-strings
           Store string constants in the writable data segment
           and don't uniquize them.  This is for compatibility
           with old programs which assume they can write into
           string constants.

           Writing into string constants is a very bad idea;
           ``constants'' should be constant.

       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 lan­
       guage 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 lan­
       guage 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 1 is the ver­
           sion 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 1.

       -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 allo­
           cated.  The current Working Paper requires that "oper­
           ator new" never return a null pointer, so this check
           is normally unnecessary.

           An alternative to using this option is to specify that
           that support has been added for putting variables into
           BSS without making them common.

       -fno-const-strings
           Give string constants type "char *" instead of type
           "const char *".  By default, G++ uses type "const char
           *" as required by the standard.  Even if you use
           -fno-const-strings, you cannot actually modify the
           value of a string constant, unless you also use
           -fwritable-strings.

           This option might be removed in a future release of
           G++.  For maximum portability, you should structure
           your code so that it works with string constants that
           have type "const char *".

       -fdollars-in-identifiers
           Accept $ in identifiers.  You can also explicitly pro­
           hibit use of $ with the option -fno-dollars-in-identi­
           fiers.  (GNU C allows $ by default on most target sys­
           tems, but there are a few exceptions.)  Traditional C
           allowed the character $ to form part of identifiers.
           However, ISO C and C++ forbid $ in identifiers.

       -fno-elide-constructors
           The C++ standard allows an implementation to omit cre­
           ating 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 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.  The compiler will
           still optimize based on the exception specifications.

       -fexternal-templates
           Cause #pragma interface and implementation to apply to
           template instantiation; template instances are emitted
           or not according to the location of the template defi­
           nition.

           This option is deprecated.

       -falt-external-templates
           Similar to -fexternal-templates, but template
           instances are emitted or not according to the place
           where they are first instantiated.

           This option is deprecated.
           style code that would otherwise be invalid, or have
           different behavior.

       -fno-gnu-keywords
           Do not recognize "typeof" as a keyword, so that code
           can use this word 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
           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 opti­
           mization will need the same set of explicit instantia­
           tions.

       -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 messages about nonconformant code from
           errors to warnings.  By default, G++ effectively sets
           save some space by using this flag.  Note that excep­
           tion handling uses the same information, but it will
           generate it as needed.

       -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 detect endless recursions during
           template class instantiation.  ANSI/ISO C++ conforming
           programs must not rely on a maximum depth greater than
           17.

       -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 destruc­
           tors, but will only work if your C library supports
           "__cxa_atexit".

       -fvtable-gc
           Emit special relocations for vtables and virtual func­
           tion references so that the linker can identify unused
           virtual functions and zero out vtable slots that refer
           to them.  This is most useful with -ffunction-sections
           and -Wl,--gc-sections, in order to also discard the
           functions themselves.

           This optimization requires GNU as and GNU ld.  Not all
           systems support this option.  -Wl,--gc-sections is
           ignored without -static.

       -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 direc­
           tories 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 genera­
           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 gener­
           ated by G++ may not be binary compatible with code
           generated by other compilers.

           The known incompatibilities at this point include:

           ·   Incorrect handling of tail-padding for bit-fields.
               G++ may attempt to pack data into the same byte as
               a base class.  For example:

                       struct A { virtual void f(); int f1 : 1; };
                       struct B : public A { int f2 : 1; };

               In this case, G++ will place "B::f2" into the same
               byte as"A::f1"; other compilers will not.  You can
               avoid this problem by explicitly padding "A" so
               that its size is a multiple of the byte size on
               your platform; that will cause G++ and other com­
               pilers to layout "B" identically.

           ·   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".

               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.

       -Wctor-dtor-privacy (C++ only)
           Warn when a class seems unusable, because all the con­
           structors or destructors in a class are private and
           the class has no friends or public static member func­
           tions.  This warning is enabled by default.

       -Wnon-virtual-dtor (C++ only)
           Warn when a class declares a non-virtual destructor
           that should probably be virtual, because it looks like
           the class will be used polymorphically.  This warning
           is enabled by -Wall.

       -Wreorder (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) { }
                   };

           Here the compiler will warn that the member initializ­
           ers for i and j will be rearranged to match the decla­
           ration order of the members.  This warning is enabled
           by -Wall.

       The following -W... options are not affected by -Wall.

       -Weffc++ (C++ only)
           Warn about violations of the following style guide­
           lines from Scott Meyers' Effective C++ book:

               must return an object.

           and 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 ",".

           If you use this option, you should be aware that the
           standard library headers do not obey all of these
           guidelines; you can use grep -v to filter out those
           warnings.

       -Wno-deprecated (C++ only)
           Do not warn about usage of deprecated features.

       -Wno-non-template-friend (C++ only)
           Disable warnings when non-templatized friend functions
           are declared within a template.  With the advent of
           explicit template specification support in G++, if the
           name of the friend is an unqualified-id (i.e., friend
           foo(int)), the C++ language specification demands that
           the friend declare or define an ordinary, nontemplate
           function.  (Section 14.5.3).  Before G++ implemented
           explicit specification, unqualified-ids could be
           interpreted as a particular specialization of a tem­
           platized function.  Because this non-conforming behav­
           ior 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 con­
           formant compiler code but disables the helpful warn­
           ing.

       -Wold-style-cast (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
           (static_cast, reinterpret_cast, and const_cast) are
           less vulnerable to unintended effects, and much easier
           to grep for.

       -Woverloaded-virtual (C++ only)
           Warn when a function declaration hides virtual func­
           tions from a base class.  For example, in:

                   struct A {
                     virtual void f();
                   };

           to member function to a plain pointer.

       -Wsign-promo (C++ only)
           Warn when overload resolution chooses a promotion from
           unsigned or enumeral type to a signed type over a con­
           version to an unsigned type of the same size.  Previ­
           ous versions of G++ would try to preserve unsigned­
           ness, but the standard mandates the current behavior.

       -Wsynth (C++ only)
           Warn when G++'s synthesis behavior does not match that
           of cfront.  For instance:

                   struct A {
                     operator int ();
                     A& operator = (int);
                   };

                   main ()
                   {
                     A a,b;
                     a = b;
                   }

           In this example, G++ will synthesize a default A&
           operator = (const A&);, while cfront will use the
           user-defined operator =.

       Options Controlling Objective-C Dialect

       This section describes the command-line options that are
       only meaningful for Objective-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 com­
       pile a file "some_class.m" like this:

               gcc -g -fgnu-runtime -O -c some_class.m

       In this example, only -fgnu-runtime is an option meant
       only for Objective-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
       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 "NXCon­
           stantString".

       -fgnu-runtime
       -Wno-protocol
           If a class is declared to implement a protocol, a
           warning is issued for every method in the protocol
           that is not implemented by the class.  The default
           behavior is to issue a warning for every method not
           explicitly implemented in the class, even if a method
           implementation is inherited from the superclass.  If
           you use the "-Wno-protocol" option, then methods
           inherited from the superclass are considered to be
           implemented, and no warning is issued for them.

       -Wselector
           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
           that for each selector appearing in a "@selector(...)"
           expression, a corresponding method with that selector
           has been found during compilation.  Because these
           checks scan the method table only at the end of compi­
           lation, 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.

       -Wundeclared-selector
           Warn if a "@selector(...)" expression referring to an
           undeclared selector is found.  A selector is consid­
           ered undeclared if no method with that name has been
           declared (explicitly, in an @interface or @protocol
           declaration, or implicitly, in an @implementation sec­
           tion) before the "@selector(...)" expression.  This
           option always performs its checks as soon as a
           "@selector(...)" expression is found (while "-Wselec­
           tor" only performs its checks in the final stage of
           compilation), and so additionally enforces the coding
           style convention that methods and selectors must be
           declared before being used.

       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

       -fdiagnostics-show-location=every-line
           Only meaningful in line-wrapping mode.  Instructs the
           diagnostic messages reporter to emit the same source
           location information (as prefix) for physical lines
           that result from the process of breaking a message
           which is too long to fit on a single line.

       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.

       You can request many specific warnings with options begin­
       ning -W, for example -Wimplicit to request warnings on
       implicit declarations.  Each of these specific warning
       options also has a negative form beginning -Wno- to turn
       off warnings; for example, -Wno-implicit.  This manual
       lists only one of the two forms, whichever is not the
       default.

       The following options control the amount and kinds of
       warnings produced by GCC; for further, language-specific
       options also refer to @ref{C++ Dialect Options} and
       @ref{Objective-C Dialect Options}.

       -fsyntax-only
           Check the code for syntax errors, but don't do any­
           thing beyond that.

       -pedantic
           Issue all the warnings demanded by strict ISO C and
           ISO C++; reject all programs that use forbidden exten­
           sions, and some other programs 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 prop­
           erly 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.
           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 defini­
           tion 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.

       -w  Inhibit all warning messages.

       -Wno-import
           Inhibit warning messages about the use of #import.

       -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.

       -Wcomment
           Warn whenever a comment-start sequence /* appears in a
           /* comment, or whenever a Backslash-Newline appears in
           a // comment.

       -Wformat
           Check calls to "printf" and "scanf", etc., to make
           sure that the arguments supplied have types appropri­
           ate to the format string specified, and that the con­
           versions specified in the format string make sense.
           This includes standard functions, and others specified
           by format attributes, in the "printf", "scanf", "strf­
           time" and "strfmon" (an X/Open extension, not in the C
           standard) families.

           The formats are checked against the format features
           supported by GNU libc version 2.2.  These include all
           ISO C90 and C99 features, as well as features from the
           Single Unix Specification and some BSD and GNU exten­
           sions.  Other library implementations may not support
           all these features; GCC does not support warning about
           features that go beyond a particular library's limita­
           tions.  However, if -pedantic is used with -Wformat,
           warnings will be given about format features not in
           the selected standard version (but not for "strfmon"
           formats, since those are not in any version of the C
           If -Wformat is specified, do not warn about "strftime"
           formats which may yield only a two-digit year.

       -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 specifica­
           tions, 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
           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 for­
           mat functions that represent possible security prob­
           lems.  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 con­
           tains %n.  (This is currently a subset of what -Wfor­
           mat-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.  Currently equivalent to -Wformat -Wfor­
           mat-nonliteral -Wformat-security.

       -Wnonnull
           Enable warning about passing a null pointer for argu­
           ments marked as requiring a non-null value by the
           "nonnull" function attribute.
           ration.

       -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.

       -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 } };

       -Wparentheses
           Warn if parentheses are omitted in certain contexts,
           such as when there is an assignment in a context where
           a truth value is expected, or when operators are
           nested whose precedence people often get confused
           about.

           Also warn about constructions where there may be con­
           fusion to which "if" statement an "else" branch
           belongs.  Here is an example of such a case:

                   {
                     if (a)
                       if (b)
                         foo ();
                     else
                       bar ();
                   }

           In 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 enclos­
           ing "if".  The resulting code would look like this:

                   {
                     if (a)
                       {
                         if (b)
                           foo ();

           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 expres­
           sion), 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 func­
           tion), 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 specified.  However, the
           standards committee have ruled that function calls do
           not overlap.

           It is not specified when between sequence points modi­
           fications to the values of objects take effect.  Pro­
           grams whose behavior depends on this have undefined
           behavior; the C standard specifies that ``Between the
           previous and next sequence point an object shall have
           its stored value modified at most once by the evalua­
           tion of an expression.  Furthermore, the prior value
           shall be read only to determine the value to be
           stored.''.  If a program breaks these rules, the
           results on any particular implementation are entirely
           unpredictable.

           Examples of code with undefined behavior are "a =
           a++;", "a[n] = 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 present implementation of this option only works
           for C programs.  A future implementation may also work
           for C++ programs.

           The C standard is worded confusingly, therefore there
           is some debate over the precise meaning of the
           sequence point rules in subtle cases.  Links to dis­
           cussions of the problem, including proposed formal
           definitions, may be found on our readings page, at
           <http://gcc.gnu.org/readings.html>.

       -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

       -Wswitch-default
           Warn whenever a "switch" statement does not have a
           "default" case.

       -Wswitch-enum
           Warn whenever a "switch" statement has an index of
           enumeral 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.

       -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.

       -Wunused-label
           Warn whenever a label is declared but not used.

           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

           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 expression to void.

       -Wunused
           All the above -Wunused options combined.

           In order to get a warning about an unused function
           parameter, you must either specify -W -Wunused or sep­
           arately specify -Wunused-parameter.

       -Wuninitialized
           structures, unions or arrays, even when they are in
           registers.

           Note that there may be no warning about a variable
           that is used only to compute a value that itself is
           never used, because such computations may be deleted
           by data flow analysis before the warnings are printed.

           These warnings are made optional because GCC is not
           smart enough to see all the reasons why the code might
           be correct despite appearing to have an error.  Here
           is one example of how this can happen:

                   {
                     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 can­
           not 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.

           active.  It warns about code which might break the
           strict aliasing rules that the compiler is using for
           optimization. The warning does not catch all cases,
           but does attempt to catch the more common pitfalls. It
           is included in -Wall.

       -Wall
           All of the above -W options combined.  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 @ref{C++ Dialect Options} and
           @ref{Objective-C Dialect Options}.

       The following -W... options are not implied by -Wall.
       Some of them warn about constructions that users generally
       do not consider questionable, but which occasionally you
       might wish to check for; others warn about constructions
       that are necessary or hard to avoid in some cases, and
       there is no simple way to modify the code to suppress the
       warning.

       -W  Print extra warning messages for these events:

           ·   A function can return either with or without a
               value.  (Falling off the end of the function body
               is considered returning without a value.)  For
               example, this function would evoke such a warning:

                       foo (a)
                       {
                         if (a > 0)
                           return a;
                       }

           ·   An expression-statement or the left-hand side of a
               comma expression contains no side effects.  To
               suppress the warning, cast the unused expression
               to void.  For example, an expression such as
               x[i,j] will cause a warning, but x[(void)i,j] will
               not.

           ·   An unsigned value is compared against zero with <
               or <=.

           ·   A comparison like x<=y<=z appears; this is equiva­
               lent to (x<=y ? 1 : 0) <= z, which is a different
               interpretation from that of ordinary mathematical
               notation.

           ·   Storage-class specifiers like "static" are not the
           ·   A comparison between signed and unsigned values
               could produce an incorrect result when the signed
               value is converted to unsigned.  (But don't warn
               if -Wno-sign-compare is also specified.)

           ·   An aggregate has a partly bracketed initializer.
               For example, the following code would evoke such a
               warning, because braces are missing around the
               initializer for "x.h":

                       struct s { int f, g; };
                       struct t { struct s h; int i; };
                       struct t x = { 1, 2, 3 };

           ·   An aggregate has an initializer which does not
               initialize all members.  For example, the follow­
               ing code would cause such a warning, because "x.h"
               would be implicitly initialized to zero:

                       struct s { int f, g, h; };
                       struct s x = { 3, 4 };

       -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 nor­
           mally 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 head­
           ers---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 conve­
           nient (for the programmer) to consider floating-point
           values as approximations to infinitely precise real
           numbers.  If you are doing this, then you need to com­
           pute (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 compar­
           isons (and when producing output, but that's a differ­
               replacement takes place within string literals,
               but does not in ISO C.

           ·   In traditional C, some preprocessor directives did
               not exist.  Traditional preprocessors would only
               consider a line to be a directive if the #
               appeared in column 1 on the line.  Therefore
               -Wtraditional warns about directives that tradi­
               tional C understands but would ignore because the
               # does not appear as the first character on the
               line.  It also suggests you hide directives like
               #pragma not understood by traditional C by indent­
               ing them.  Some traditional implementations would
               not recognize #elif, so it suggests avoiding it
               altogether.

           ·   A function-like macro that appears without argu­
               ments.

           ·   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 pre­
               processor 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 differ­
               ent 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 val­
               ues, which typically represent bit patterns, are
               not warned about.

           ·   Usage of ISO string concatenation is detected.

           ·   Initialization of automatic aggregates.
               prototypes when compiling with traditional C would
               cause serious problems.  This is a subset of the
               possible conversion warnings, for the full set use
               -Wconversion.

           ·   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.

       -Wendif-labels
           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.

       -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.

       -Wbad-function-cast (C only)
           Warn whenever a function call is cast to a non-match­
           ing type.  For example, warn if "int malloc()" is cast
           to "anything *".

       -Wcast-qual
           Warn whenever a pointer is cast so as to remove a type
           qualifier from the target type.  For example, warn if
           a "const char *" is 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
           these warnings.

       -Wconversion
           Warn if a prototype causes a type conversion that is
           different from what would happen to the same argument
           in the absence of a prototype.  This includes conver­
           sions of fixed point to floating and vice versa, and
           conversions changing the width or signedness of a
           fixed point argument except when the same as the
           default promotion.

           Also, warn if a negative integer constant expression
           is implicitly converted to an unsigned type.  For
           example, warn about the assignment "x = -1" if "x" is
           unsigned.  But do not warn about explicit casts like
           "(unsigned) -1".

       -Wsign-compare
           Warn when a comparison between signed and unsigned
           values could produce an incorrect result when the
           signed value is converted to unsigned.  This warning
           is also enabled by -W; to get the other warnings of -W
           without this warning, use -W -Wno-sign-compare.

       -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.)

       -Wstrict-prototypes (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.)

       -Wmissing-prototypes (C only)
           Warn if a global function is defined without a previ­
           ous prototype declaration.  This warning is issued
           even if the definition itself provides a prototype.
           The aim is to detect global functions that fail to be
           declared in header files.

       -Wmissing-declarations
           Warn if a global function is defined without a previ­
           ous declaration.  Do so even if the definition itself
           provides a prototype.  Use this option to detect
           global functions that are not declared in header
           files.

       -Wmissing-noreturn
           Warn about functions which might be candidates for
           attribute "noreturn".  Note these are only possible
           be the case, and some functions for which "format"
           attributes are appropriate may not be detected.  This
           option has no effect unless -Wformat is enabled (pos­
           sibly by -Wall).

       -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 implementation-defined values, and
           should not be used in portable code.

       -Wno-deprecated-declarations
           Do not warn about uses of functions, variables, and
           types marked as deprecated by using the "deprecated"
           attribute.  (@pxref{Function Attributes}, @pxref{Vari­
           able Attributes}, @pxref{Type Attributes}.)

       -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 instance, in this
           code, the variable "f.x" in "struct bar" will be mis­
           aligned even though "struct bar" does not itself have
           the packed attribute:

                   struct foo {
                     int x;
                     char a, b, c, d;
                   } __attribute__((packed));
                   struct bar {
                     char z;
                     struct foo f;
                   };

       -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 only)
           Warn if an "extern" declaration is encountered within
           a function.

       -Wunreachable-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 substan­
           tial code which checks correct functioning of the pro­
           gram and is, hopefully, unreachable because the pro­
           gram does work.  Another common use of unreachable
           code is to provide behavior which is selectable at
           compile-time.

       -Winline
           Warn if a function can not be inlined and it was
           declared as inline.

       -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.

       -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 when the optimization itself is likely to
           take inordinate amounts of time.

       -Werror
           Make all warnings into errors.

       Options for Debugging Your Program or GCC

       GCC has various special options that are used for debug­
       ging either your program or GCC:

       -g  Produce debugging information in the operating sys­
           tem's native format (stabs, COFF, XCOFF, or DWARF).
           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, -gdwarf-1+,
           -gdwarf-1, or -gvms (see below).

           The following options are useful when GCC is generated
           with the capability for more than one debugging for­
           mat.

       -ggdb
           Produce debugging information for use by GDB.  This
           means to use the most expressive format available
           (DWARF 2, stabs, or the native format if neither of
           those are supported), including GDB extensions if at
           all possible.

       -gstabs
           Produce debugging information in stabs format (if that
           is supported), without GDB extensions.  This is the
           format used by DBX on most BSD systems.  On MIPS,
           Alpha and System V Release 4 systems this option pro­
           duces stabs debugging output which is not understood
           by DBX or SDB.  On System V Release 4 systems this
           option requires the GNU assembler.

       -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
           Produce debugging information in DWARF version 1 for­
           mat (if that is supported).  This is the format used
           by SDB on most System V Release 4 systems.

           This option is deprecated.

       -gvms
           Produce debugging information in VMS debug format (if
           that is supported).  This is the format used by DEBUG
           on VMS systems.

       -glevel
       -ggdblevel
       -gstabslevel
       -gcofflevel
       -gxcofflevel
       -gvmslevel
           Request debugging information and also use level to
           specify how much information.  The default level is 2.

           Level 1 produces minimal information, enough for mak­
           ing backtraces in parts of the program that you don't
           plan to debug.  This includes descriptions of func­
           tions 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 debug­
           gers support macro expansion when you use -g3.

           Note that in order to avoid confusion between DWARF1
           debug level 2, and DWARF2, neither -gdwarf nor
           -gdwarf-2 accept a concatenated debug level.  Instead
           use an additional -glevel option to change the debug
           level for DWARF1 or DWARF2.

       -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.

       -p  Generate extra code to write profile information suit­
           able 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 suit­
           able 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
           name is generated from the name of the output file, if
           explicitly specified and it is not the final exe­
           cutable, otherwise it is the basename of the source
           file. In both cases any suffix is removed (e.g.
           foo.da for input file dir/foo.c, or dir/foo.da for
           output file specified as -o dir/foo.o).

           For profile-directed block ordering, compile the pro­
           gram with -fprofile-arcs plus optimization and code
           generation options, generate the arc profile informa­
           tion by running the program on a selected workload,
           and then compile the program again with the same opti­
           mization and code generation options plus
           -fbranch-probabilities.

           The other use of -fprofile-arcs is for use with gcov,
           when it is used with the -ftest-coverage option.

           With -fprofile-arcs, for each function of your program
           GCC creates a program flow graph, then finds a span­
           ning tree for the graph.  Only arcs that are not on
           the spanning tree have to be instrumented: the com­
           piler 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
           Create data files for the gcov code-coverage utility.
           See -fprofile-arcs option above for a description of
           auxname.

           auxname.bb
               A mapping from basic blocks to line numbers, which
               gcov uses to associate basic block execution
               counts with line numbers.

           auxname.bbg
               A list of all arcs in the program flow graph.
               This allows gcov to reconstruct the program flow
               graph, so that it can compute all basic block and
               arc execution counts from the information in the
               auxname.da file.

           Use -ftest-coverage with -fprofile-arcs; the latter
           option adds instrumentation to the program, which then
           writes execution counts to another data file:

           auxname.da
               Runtime arc execution counts, used in conjunction

           foo.00.rtl or foo.01.sibling).  Here are the possible
           letters for use in letters, and their meanings:

           A   Annotate the assembler output with miscellaneous
               debugging information.

           b   Dump after computing branch probabilities, to
               file.14.bp.

           B   Dump after block reordering, to file.32.bbro.

           c   Dump after instruction combination, to the file
               file.19.combine.

           C   Dump after the first if conversion, to the file
               file.15.ce1.

           d   Dump after delayed branch scheduling, to
               file.34.dbr.

           D   Dump all macro definitions, at the end of prepro­
               cessing, in addition to normal output.

           e   Dump after SSA optimizations, to file.04.ssa and
               file.07.ussa.

           E   Dump after the second if conversion, to
               file.29.ce3.

           f   Dump after life analysis, to file.18.life.

           F   Dump after purging "ADDRESSOF" codes, to
               file.10.addressof.

           g   Dump after global register allocation, to
               file.24.greg.

           h   Dump after finalization of EH handling code, to
               file.02.eh.

           k   Dump after reg-to-stack conversion, to
               file.31.stack.

           o   Dump after post-reload optimizations, to
               file.25.postreload.

           G   Dump after GCSE, to file.11.gcse.

           i   Dump after sibling call optimizations, to
               file.01.sibling.

           j   Dump after the first jump optimization, to

           N   Dump after the register move pass, to file.21.reg­
               move.

           r   Dump after RTL generation, to file.00.rtl.

           R   Dump after the second scheduling pass, to
               file.30.sched2.

           s   Dump after CSE (including the jump optimization
               that sometimes follows CSE), to file.09.cse.

           S   Dump after the first scheduling pass, to
               file.22.sched.

           t   Dump after the second CSE pass (including the jump
               optimization that sometimes follows CSE), to
               file.17.cse2.

           u   Dump after null pointer elimination pass to
               file.08.null.

           w   Dump after the second flow pass, to file.26.flow2.

           X   Dump after SSA dead code elimination, to
               file.06.ssadce.

           z   Dump after the peephole pass, to file.27.peep­
               hole2.

           a   Produce all the dumps listed above.

           m   Print statistics on memory usage, at the end of
               the run, to standard error.

           p   Annotate the assembler output with a comment indi­
               cating which pattern and alternative was used.
               The length of each instruction is also printed.

           P   Dump the RTL in the assembler output as a comment
               before each instruction.  Also turns on -dp anno­
               tation.

           v   For each of the other indicated dump files (except
               for file.00.rtl), dump a representation of the
               control flow graph suitable for viewing with VCG
               to file.pass.vcg.

           x   Just generate RTL for a function instead of com­
               piling it.  Usually used with r.

           y   Dump debugging information during parsing, to
           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)
       -fdump-class-hierarchy-options (C++ only)
           Dump a representation of each class's hierarchy and
           virtual function table layout to a file.  The file
           name is made by appending .class 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-tree-switch (C++ only)
       -fdump-tree-switch-options (C++ only)
           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 suf­
           fix 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 meaning­
           ful will be ignored. The following options are avail­
           able

           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.

           all Turn on all options.

           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.

           inlined
               Dump after function inlining, to file.inlined.

           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-ver­
           bose also includes dependence info.

       -save-temps
           Store the usual ``temporary'' intermediate files per­
           manently; 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 nor­
           mally uses an integrated preprocessor.

       -time
           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).  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 time,'' time spent executing
           operating system routines on behalf of the program.
           Both numbers are in seconds.

       -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{-, with­
           out spaces between multiple switches.  This is sup­
           posed to ease shell-processing.

       -print-prog-name=program
           Like -print-file-name, but searches for a program such
           as cpp.

           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 '/'.

       -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.)

       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 pro­
       duce 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.

       Turning on optimization flags makes the compiler attempt
       to improve the performance and/or code size at the expense
       of compilation time and possibly the ability to debug the
       program.

       Not all optimizations are controlled directly by a flag.
       Only optimizations that have a flag are listed.

       -O
       -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: -fde­

           -O2 turns on all optimization flags specified by -O.
           It also turns on the following optimization flags:
           -fforce-mem -foptimize-sibling-calls -fstrength-reduce
           -fcse-follow-jumps  -fcse-skip-blocks -fre­
           run-cse-after-loop  -frerun-loop-opt -fgcse
           -fgcse-lm   -fgcse-sm -fdelete-null-pointer-checks
           -fexpensive-optimizations -fregmove -fschedule-insns
           -fschedule-insns2 -fsched-interblock -fsched-spec
           -fcaller-saves -fpeephole2 -freorder-blocks  -fre­
           order-functions -fstrict-aliasing -falign-functions
           -falign-jumps -falign-loops  -falign-labels

           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-func­
           tions, -fweb, -funit-at-a-time, -ftracer,
           -funswitch-loops and -frename-registers options.

       -O0 Do not optimize.  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  -falign-jumps  -falign-loops
           -falign-labels  -freorder-blocks
           -fprefetch-loop-arrays

           If you use multiple -O options, with or without level
           numbers, the last such option is the one that is
           effective.

       Options of the form -fflag specify machine-independent
       flags.  Most flags have both positive and negative forms;
       the negative form of -ffoo would be -fno-foo.  In the
       table below, only one of the forms is listed---the one you
       typically will use.  You can figure out the other form by
       either removing no- or adding it.

       The following options control specific optimizations.
       They are either 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

       -fforce-mem
           Force memory operands to be copied into registers
           before doing arithmetic on them.  This produces better
           code by making all memory references potential common
           subexpressions.  When they are not common subexpres­
           sions, instruction combination should eliminate the
           separate register-load.

           Enabled at levels -O2, -O3, -Os.

       -fforce-addr
           Force memory address constants to be copied into reg­
           isters before doing arithmetic on them.  This may pro­
           duce better code just as -fforce-mem may.

       -fomit-frame-pointer
           Don't keep the frame pointer in a register for func­
           tions that don't need one.  This avoids the instruc­
           tions to save, set up and restore frame pointers; it
           also makes an extra register available in many func­
           tions.  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 automat­
           ically handles the frame pointer and nothing is saved
           by pretending it doesn't exist.  The machine-descrip­
           tion 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 expand­
           ing any functions inline.  Note that if you are not
           optimizing, no functions can be expanded inline.

       -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
           lation time and memory consumption.  Decreasing usu­
           ally makes the compilation faster and less code will
           be inlined (which presumably means slower programs).
           This option is particularly useful for programs that
           use inlining heavily such as those based on recursive
           templates with C++.

           Inlining is actually controlled by a number of parame­
           ters, which may be specified individually by using
           --param name=value.  The -finline-limit=n option sets
           some of these parameters as follows:

            @item max-inline-insns
             is set to I<n>.
            @item max-inline-insns-single
             is set to I<n>/2.
            @item max-inline-insns-single-auto
             is set to I<n>*2/5.
            @item min-inline-insns
             is set to 130 or I<n>/4, whichever is smaller.
            @item max-inline-insns-rtl
             is set to I<n>.

           Using -finline-limit=600 thus results in the default
           settings for these parameters.  See below for a docu­
           mentation of the individual parameters controlling
           inlining.

           Note: pseudo instruction represents, in this particu­
           lar context, an abstract measurement of function's
           size.  In no way, it represents a count of assembly
           instructions and as such its exact meaning might
           change from one release to an another.

       -fkeep-inline-functions
           Even if all calls to a given function are integrated,
           and the function is declared "static", nevertheless
           output a separate run-time callable version of the
           function.  This switch does not affect "extern inline"
           functions.

       -fkeep-static-consts
           Emit variables declared "static const" when optimiza­
           tion isn't 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 refer­
           enced, regardless of whether or not optimization is
           turned on, use the -fno-keep-static-consts option.

       -fmerge-constants
           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 non-automatic variable to have
           distinct location, so using this option will result in
           non-conforming behavior.

       -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 sup­
           port such instructions, which include x86, PowerPC,
           IA-64 and S/390.

           The default is -fbranch-count-reg, enabled when
           -fstrength-reduce is enabled.

       -fno-function-cse
           Do not put function addresses in registers; make each
           instruction that calls a constant function contain the
           function's address explicitly.

           This option results in less efficient code, but some
           strange hacks that alter the assembler output may be
           confused by the optimizations performed when this
           option is not used.

           The default is -ffunction-cse

       -fno-zero-initialized-in-bss
           If the target supports a BSS section, GCC by default
           puts variables that are initialized to zero into BSS.
           This can save space in the resulting code.

           This option turns off this behavior because some pro­
           grams 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 assump­
           tions based on that.

           The default is -fzero-initialized-in-bss.

       -fstrength-reduce
           Perform the optimizations of loop strength reduction
           and elimination of iteration variables.

           Enabled at levels -O2, -O3, -Os.

       -fthread-jumps
           CSE will follow the jump when the condition tested is
           false.

           Enabled at levels -O2, -O3, -Os.

       -fcse-skip-blocks
           This is similar to -fcse-follow-jumps, but causes CSE
           to follow jumps which conditionally skip over blocks.
           When CSE encounters a simple "if" statement with no
           else clause, -fcse-skip-blocks causes CSE to follow
           the jump around the body of the "if".

           Enabled at levels -O2, -O3, -Os.

       -frerun-cse-after-loop
           Re-run common subexpression elimination after loop
           optimizations has been performed.

           Enabled at levels -O2, -O3, -Os.

       -frerun-loop-opt
           Run the loop optimizer twice.

           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 elimi­
           nation 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
           Perform cross-jumping transformation. This transforma­
           tion unifies equivalent code and save code size. The
           resulting code may or may not perform better than
           without cross-jumping.

           Enabled at levels -O, -O2, -O3, -Os.

       -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 avail­
           able is controlled by "if-conversion2".

           Enabled at levels -O, -O2, -O3, -Os.

       -fif-conversion2
           Use conditional execution (where available) to trans­
           form 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 opti­
           mization for programs which depend on that behavior.

           Enabled at levels -O2, -O3, -Os.

       -fexpensive-optimizations
           Perform a number of minor optimizations that are rela­
           tively expensive.

           Enabled at levels -O2, -O3, -Os.

       -foptimize-register-move
       -fregmove
           Attempt to reassign register numbers in move instruc­
           tions 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
           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 addi­
           tional pass of instruction scheduling after register
           allocation has been done.  This is especially useful
           on machines with a relatively small number of regis­
           ters and where memory load instructions take more than
           one cycle.

           Enabled at levels -O2, -O3, -Os.

       -fno-sched-interblock
           Don't schedule instructions across basic blocks.  This
           is normally enabled by default when scheduling before
           register allocation, i.e.  with -fschedule-insns or at
           -O2 or higher.

       -fno-sched-spec
           Don't allow speculative motion of non-load instruc­
           tions.  This is normally enabled by default when
           scheduling before register allocation, i.e.  with
           -fschedule-insns or at -O2 or higher.

       -fsched-spec-load
           Allow speculative motion of some load instructions.
           This only 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.

       -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
           by default when you use the optimizer.

           These options may generate better or worse code;
           results are highly dependent on the structure of loops
           within the source code.

           These two options are intended to be removed someday,
           once they have helped determine the efficacy of vari­
           ous approaches to improving loop optimizations.

           Please let us (<gcc@gcc.gnu.org> and <for­
           tran@gnu.org>) know how use of these options affects
           the performance of your production code.  We're very
           interested in code that runs slower when these options
           are enabled.

       -fno-peephole
       -fno-peephole2
           Disable any machine-specific peephole optimizations.
           The difference between -fno-peephole and -fno-peep­
           hole2 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.

       -fbranch-probabilities
       -fno-guess-branch-probability
           Do not guess branch probabilities using a randomized
           model.

           Sometimes gcc will opt to use a randomized model to
           guess branch probabilities, when none are available
           from either profiling feedback (-fprofile-arcs) or
           __builtin_expect.  This means that different runs of
           the compiler on the same program may produce different
           object code.

           In a hard real-time system, people don't want differ­
           ent runs of the compiler to produce code that has dif­
           ferent behavior; minimizing non-determinism is of
           paramount import.  This switch allows users to reduce
           non-determinism, possibly at the expense of inferior
           optimization.

           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
           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
           Allows 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() {
                     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() {
                     a_union t;
                     int* ip;
                     t.d = 3.0;
                     ip = &t.i;
                     return *ip;
                   }

           Every language that wishes to perform language-spe­
           cific alias analysis should define a function that
           computes, given an "tree" node, an alias set for the
           node.  Nodes in different alias sets are not allowed
           to alias.  For an example, see the C front-end func­
           tion "c_get_alias_set".
           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, 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.

           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, use a machine-dependent default
           which is very likely to be 1, meaning no alignment.

           Enabled at levels -O2, -O3.

       -falign-loops
       -falign-loops=n
           Align loops to a power-of-two boundary, skipping up to
           n bytes like -falign-functions.  The hope is that the
           loop will be executed many times, which will make up
           for any execution of the dummy operations.

           If n is not specified, 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-func­
           tions.  In this case, no dummy operations need be exe­
           cuted.

           If n is not specified, use a machine-dependent
           default.

           Enabled at levels -O2, -O3.

           optimizer and trivial dead code remover.  It can, how­
           ever, make debugging impossible, since variables will
           no longer stay in a ``home register''.

           Enabled at levels -O3.

       -fno-cprop-registers
           After register allocation and post-register allocation
           instruction splitting, we perform a copy-propagation
           pass to try to reduce scheduling dependencies and
           occasionally eliminate the copy.

           Disabled at levels -O, -O2, -O3, -Os.

       The following options control compiler behavior regarding
       floating point arithmetic.  These options trade off
       between speed and correctness.  All must be specifically
       enabled.

       -ffloat-store
           Do not store floating point variables in registers,
           and inhibit other options that might change whether a
           floating point value is taken from a register or mem­
           ory.

           This option prevents undesirable excess precision on
           machines such as the 68000 where the floating regis­
           ters (of the 68881) keep more precision than a "dou­
           ble" is supposed to have.  Similarly for the x86
           architecture.  For most programs, the excess precision
           does only good, but a few programs rely on the precise
           definition of IEEE floating point.  Use -ffloat-store
           for such programs, after modifying them to store all
           pertinent intermediate computations into variables.

       -ffast-math
           Sets -fno-math-errno, -funsafe-math-optimizations,
           -fno-trapping-math, -ffinite-math-only and -fno-sig­
           naling-nans.

           This option causes the preprocessor macro
           "__FAST_MATH__" to be defined.

           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.

       -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
           link-time, it may include libraries or startup files
           that change the default FPU control word or other sim­
           ilar optimizations.

           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 -fno-unsafe-math-optimizations.

       -ffinite-math-only
           Allow optimizations for floating-point arithmetic that
           assume that arguments and results are not NaNs or
           +-Infs.

           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.

           The default is -fno-finite-math-only.

       -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 implies
           -fno-signaling-nans.  Setting this option may allow
           faster code if one relies on ``non-stop'' IEEE arith­
           metic, 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.

       -fsignaling-nans
           Compile code assuming that IEEE signaling NaNs may
           generate user-visible traps during floating-point
           operations.  Setting this option disables optimiza­
           tions that may change the number of exceptions visible
           with signaling NaNs.  This option implies -ftrap­
           ping-math.

           This option causes the preprocessor macro "__SUP­
           PORT_SNAN__" to be defined.

           The default is -fno-signaling-nans.

       -fbranch-probabilities
           After running a program compiled with -fprofile-arcs,
           you can compile it a second time using -fbranch-proba­
           bilities, to improve optimizations based on the number
           of times each branch was taken.  When the program com­
           piled with -fprofile-arcs exits it saves arc execution
           counts to a file called sourcename.da for each source
           file  The information in this data file is very depen­
           dent on the structure of the generated code, so you
           must use the same source code and the same optimiza­
           tion options for both compilations.

           With -fbranch-probabilities, GCC puts a REG_BR_PROB
           note on each JUMP_INSN and CALL_INSN.  These can be
           used to improve optimization.  Currently, they are
           only used in one place: in reorg.c, instead of guess­
           ing which path a branch is mostly to take, the
           REG_BR_PROB values are used to exactly determine which
           path is taken more often.

       -fnew-ra
           Use a graph coloring register allocator.  Currently
           this option is meant for testing, so we are interested
           to hear about miscompilations with -fnew-ra.

       -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 deter­
           mined at compile time or upon entry to the loop.
           -funroll-loops implies both -fstrength-reduce and
           -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,

       -fprefetch-loop-arrays
           If supported by the target machine, generate instruc­
           tions to prefetch memory to improve the performance of
           loops that access large arrays.

           Disabled at level -Os.

       -ffunction-sections

           Only use these options when there are significant ben­
           efits 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 spec­
           ify this option and you may have problems with debug­
           ging if you specify both this option and -g.

       -fssa
           Perform optimizations in static single assignment
           form.  Each function's flow graph is translated into
           SSA form, optimizations are performed, and the flow
           graph is translated back from SSA form.  Users should
           not specify this option, since it is not yet ready for
           production use.

       -fssa-ccp
           Perform Sparse Conditional Constant Propagation in SSA
           form.  Requires -fssa.  Like -fssa, this is an experi­
           mental feature.

       -fssa-dce
           Perform aggressive dead-code elimination in SSA form.
           Requires -fssa.  Like -fssa, this is an experimental
           feature.

       --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.

           In each case, the value is an integer.  The allowable
           choices for name are given in the following table:

           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 num­
               ber of instructions to consider when searching for

           max-gcse-passes
               The maximum number of passes of GCSE to run.

           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 represen­
               tation) 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 300.

           max-inline-insns-auto
               When you use -finline-functions (included in -O3),
               a lot of functions that would otherwise not be
               considered for inlining by the compiler will be
               investigated.  To those functions, a different
               (more restrictive) limit compared to functions
               declared inline can be applied.  The default value
               is 240.

           max-inline-insns
               The tree inliner does decrease the allowable size
               for single functions to be inlined after we
               already inlined the number of instructions given
               here by repeated inlining.  This number should be
               a factor of two or more larger than the single
               function limit.  Higher numbers result in better
               runtime performance, but incur higher compile-time
               resource (CPU time, memory) requirements and
               result in larger binaries.  Very high values are
               not advisable, as too large binaries may adversely
               affect runtime performance.  The default value is
               600.

           max-inline-slope
               After exceeding the maximum number of inlined
               instructions by repeated inlining, a linear func­
               tion is used to decrease the allowable size for
               single functions.  The slope of that function is
               the negative reciprocal of the number specified
               here.  The default value is 32.

               eter.  The default value is 600.

           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.

           hot-bb-count-fraction
               Select fraction of the maximal count of repeti­
               tions 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 execu­
               tions of basic block in function given basic block
               needs to have to be considered hot

           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 pro­
               files (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 per­
               cent).

           tracer-min-branch-ratio
           tracer-min-branch-ratio-feedback
               Stop forward growth if the best edge do have prob­
               ability lower than this threshold.

               Similarly to tracer-dynamic-coverage two values
               are present, one for compilation for profile feed­
               back and one for compilation without.  The value
               for compilation with profile feedback needs to be
               available, the notion of "RAM" is the smallest of
               actual RAM, RLIMIT_RSS, RLIMIT_DATA and RLIMIT_AS.
               If GCC is not able to calculate RAM on a particu­
               lar 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 RAM/8, with a lower bound of 4096
               (four megabytes) and an upper bound of 131072 (128
               megabytes).  If "getrlimit" is available, the
               notion of "RAM" is the smallest of actual RAM,
               RLIMIT_RSS, RLIMIT_DATA and RLIMIT_AS.  If GCC is
               not able to calculate RAM on a particular plat­
               form, the lower bound is used.  Setting this
               parameter very large effectively disables garbage
               collection.  Setting this parameter and ggc-min-
               expand to zero causes a full collection to occur
               at every opportunity.

       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 prepro­
       cessing.  Some of these options make sense only together
       with -E because they cause the preprocessor output to be
       unsuitable for actual compilation.

       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, trans­
       lated or interpreted by the compiler driver before being
       passed to the preprocessor, and -Wp forcibly bypasses this
       phase.  The preprocessor's direct interface is undocu­
       mented and subject to change, so whenever possible you
       should avoid using -Wp and let the driver handle the
       options instead.

       -D name
           Predefine name as a macro, with definition 1.
           -D'name(args...)=definition' works.

           -D and -U options are processed in the order they are
           given on the command line.  All -imacros file and
           -include file options are processed after all -D and
           -U options.

       -U name
           Cancel any previous definition of name, either built
           in or provided with a -D option.

       -undef
           Do not predefine any system-specific macros.  The com­
           mon 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 direc­
           tories.  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 .

       -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 and -Wtri­
           graphs.  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
           Warn if any trigraphs are encountered.  This option
           used to take effect only if -trigraphs was also speci­
           fied, but now works independently.  Warnings are not
           given for trigraphs within comments, as they do not
           affect the meaning of the program.

       -Wtraditional
           Warn about macros defined in the main file that are
           unused.  A macro is used if it is expanded or tested
           for existence at least once.  The preprocessor will
           also warn if the macro has not been used at the time
           it is redefined or undefined.

           Built-in macros, macros defined on the command line,
           and macros defined in include files are not warned
           about.

           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.

           Unless specified explicitly (with -MT or -MQ), the
           object file name consists of the basename of the
           source file with any suffix replaced with object file
           suffix.  If there are many included files then the
           rule is split into several lines using \-newline.  The
           rule has no commands.

           This option does not suppress the preprocessor's debug
           output, such as -dM.  To avoid mixing such debug out­
           put with the dependency rules you should explicitly
           specify the dependency output file with -MF, or use an
           environment variable like DEPENDENCIES_OUTPUT.  Debug
           output will still be sent to the regular output stream
           as normal.

           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 dou­
           ble 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 seman­
           tics from GCC versions 3.0 and earlier.

       -MF file
           @anchor{-MF} 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 depen­
           dency list without raising an error.  The dependency
           filename is taken directly from the "#include" direc­
           tive 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 make­
           files.

       -MP This option instructs CPP to add a phony target for
           input file, including any path, deletes any file suf­
           fix 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

                   $(objpfx)foo.o: foo.c

       -MQ target
           Same as -MT, but it quotes any characters which are
           special to Make.  -MQ '$(objpfx)foo.o' gives

                   $$(objpfx)foo.o: foo.c

           The default target is automatically quoted, as if it
           were given with -MQ.

       -MD -MD is equivalent to -M -MF file, except that -E is
           not implied.  The driver determines file based on
           whether an -o option is given.  If it is, the driver
           uses its argument but with a suffix of .d, otherwise
           it take the basename of the input file 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 @pxref{-MF}), 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 compi­
           lation process.

       -MMD
           Like -MD except mention only user header files, not
           system -header files.

       -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 con­
           formance 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

           standard may be one of:

           "iso9899:1990"
           "c89"
               The ISO C standard from 1990.  c89 is the custom­
               ary 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 head­
           ers requested with "#include "file""; they are not
           searched for "#include <file>".  If additional direc­
           tories are specified with -I options after the -I-,
           those directories are searched for all #include direc­
           tives.

           In addition, -I- inhibits the use of the directory of
           the current file directory as the first search direc­
           tory for "#include "file"".

       -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.
           "..."" search chain as normal.

           If multiple -include options are given, the files are
           included in the order they appear on the command line.

       -imacros file
           Exactly like -include, except that any output produced
           by scanning file is thrown away.  Macros it defines
           remain defined.  This allows you to acquire all the
           macros from a header without also processing its dec­
           larations.

           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.

       -iprefix prefix
           Specify prefix as the prefix for subsequent -iwithpre­
           fix 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.

           Use of these options is discouraged.

       -isystem dir
           Search dir for header files, after all directories
           specified by -I but before the standard system direc­
           tories.  Mark it as a system directory, so that it
           gets the same special treatment as is applied to the
           standard system directories.

       -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 com­
           ments, 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 tok­

       -fno-show-column
           Do not print column numbers in diagnostics.  This may
           be necessary 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.

       -A- Cancel all predefined assertions and all assertions
           preceding it on the command line.  Also, undefine all
           predefined macros and all macros preceding it on the
           command line.  (This is a historical wart and may
           change in the future.)

       -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 dur­
               ing the execution of the preprocessor, including
               predefined macros.  This gives you a way of find­
               ing 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.

           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 preprocess­
               ing.  Both kinds of output go to the standard out­
               put file.

           N   Like D, but emit only the macro names, not their
               expansions.

           I   Output #include directives in addition to the
           it causes the preprocessor to treat comments as tokens
           in their own right.  For example, comments appearing
           at the start of what would be a directive line have
           the effect of turning that line into an ordinary
           source line, since the first token on the line is no
           longer a #.

       -CC Do not discard comments, including during macro expan­
           sion.  This is like -C, except that comments contained
           within macros are also 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 com­
           ments.

       -gcc
           Define the macros __GNUC__, __GNUC_MINOR__ and
           __GNUC_PATCHLEVEL__.  These are defined automatically
           when you use gcc -E; you can turn them off in that
           case with -no-gcc.

       -traditional-cpp
           Try to imitate the behavior of old-fashioned C prepro­
           cessors, 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
           exit immediately.

       Passing Options to the Assembler

       You can pass options to the assembler.

       -Wa,option
           Pass option as an option to the assembler.  If option
           contains commas, it is split into multiple options at
           the commas.

       Options for Linking

       These options come into play when the compiler links
       object files into 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 con­
           tents.)  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 rec­
           ommended.)

           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 spec­
           ified.  Thus, foo.o -lz bar.o searches library z after
           file foo.o but before bar.o.  If bar.o refers to func­
           tions 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 libli­
           brary.a.  The linker then uses this file as if it had
           been specified precisely by name.

           The directories searched include several standard sys­
           tem directories plus any that you specify with -L.
           to link an Objective-C program.

       -nostartfiles
           Do not use the standard system startup files when
           linking.  The standard system libraries are used nor­
           mally, unless -nostdlib or -nodefaultlibs is used.

       -nodefaultlibs
           Do not use the standard system libraries when linking.
           Only the libraries you specify will be passed to the
           linker.  The standard startup files are used normally,
           unless -nostartfiles is used.  The compiler may gener­
           ate calls to memcmp, memset, and memcpy for System V
           (and ISO C) environments or to bcopy and bzero for BSD
           environments.  These entries are usually resolved by
           entries in libc.  These entry points should be sup­
           plied through some other mechanism when this option is
           specified.

       -nostdlib
           Do not use the standard system startup files or
           libraries when linking.  No startup files and only the
           libraries you specify will be passed to the linker.
           The compiler may generate calls to memcmp, memset, and
           memcpy for System V (and ISO C) environments or to
           bcopy and bzero for BSD environments.  These entries
           are 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 lan­
           guages.

           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.)

       -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.

           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 these is when the appli­
           cation wishes to throw and catch exceptions across
           different shared libraries.  In that case, each of the
           libraries as well as the application itself should use
           the shared libgcc.

           Therefore, the G++ and GCJ drivers automatically add
           -shared-libgcc whenever you build a shared library or
           a main executable, because C++ and Java programs typi­
           cally use exceptions, so this is the right thing to
           do.

           If, instead, you use the GCC driver to create shared
           libraries, you may find that they will not always be
           linked with the shared libgcc.  If GCC finds, at its
           configuration time, that you have a GNU linker that
           does not support option --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 propa­
           gate 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 lan­
           guages 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.

       -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 an 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
           of additional library modules.

       Options for Directory Search

       These options specify directories to search for header
       files, for libraries and for parts of the compiler:

       -Idir
           Add the directory dir to the head of the list of
           directories to be searched for header files.  This can
           be used to override a system header file, substituting
           your own version, since these directories are searched
           before the system header file directories.  However,
           you should not use this option to add directories that
           contain 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 direc­
           tive are not inadvertently changed.  If you really
           need to change the search order for system directo­
           ries, use the -nostdinc and/or -isystem options.

       -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.

           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-lib/.  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 pre­
           fix.

           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.

           Another way to specify a prefix much like the -B pre­
           fix is to use the environment variable GCC_EXEC_PRE­
           FIX.

           As a special kludge, if the path provided by -B is
           [dir/]stageN/, where N is a number in the range 0 to
           9, then it will be replaced by [dir/]include.  This is
           to help with boot-strapping the compiler.

       -specs=file
           Process file after the compiler reads in the standard
           specs file, in order to override the defaults that the
           gcc driver program uses when determining what switches
           to pass to cc1, cc1plus, as, ld, etc.  More than one
           -specs=file can be specified on the command line, and
           they are processed in order, from left to right.

       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 inconve­
       -V version
           The argument version specifies which version of GCC to
           run.  This is useful when multiple versions are
           installed.  For example, version might be 2.0, meaning
           to run GCC version 2.0.

       The -V and -b options work by running the
       <machine>-gcc-<version> executable, so there's no real
       reason to use them if you can just run that directly.

       Hardware Models and Configurations

       Earlier we discussed the standard option -b which chooses
       among different installed compilers for completely differ­
       ent 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 speci­
       fied.

       Some configurations of the compiler also support addi­
       tional special options, usually for compatibility with
       other compilers on the same platform.

       These options are defined by the macro "TARGET_SWITCHES"
       in the machine description.  The default for the options
       is also defined by that macro, which enables you to change
       the defaults.

       M680x0 Options

       These are the -m options defined for the 68000 series.
       The default values for these options depends on which
       style of 68000 was selected when the compiler was config­
       ured; the defaults for the most common choices are given
       below.

       -m68000
       -mc68000
           Generate output for a 68000.  This is the default when
           the compiler is configured for 68000-based systems.

           Use this option for microcontrollers with a 68000 or
           EC000 core, including the 68008, 68302, 68306, 68307,
           68322, 68328 and 68356.

       -m68020
       -mc68020
           Generate output for a 68040.  This is the default when
           the compiler is configured for 68040-based systems.

           This option inhibits the use of 68881/68882 instruc­
           tions 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.

           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.

           Use this option for microcontrollers with a CPU32 or
           CPU32+ core, including the 68330, 68331, 68332, 68333,
           68334, 68336, 68340, 68341, 68349 and 68360.

       -m5200
           Generate output for a 520X ``coldfire'' family cpu.
           This is the default when the compiler is configured
           for 520X-based systems.

           Use this option for microcontroller with a 5200 core,
           including the MCF5202, MCF5203, MCF5204 and MCF5202.

       -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.

       -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.

       -mfpa
           Generate output containing Sun FPA instructions for
           floating point.

       -msoft-float
       -mnobitfield
           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 com­
           piler.

           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.  (Nor­
           mally, 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.

       -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 bound­
           aries produces code that runs somewhat faster on pro­
           cessors with 32-bit busses at the expense of more mem­
           ory.

           Warning: if you use the -malign-int switch, GCC will
           align structures containing the above types  differ­
           ently than most published application binary interface
           specifications for the m68k.

       -mpcrel
           Use the pc-relative addressing mode of the 68000

       microcontrollers.  The default values for these options
       depends on which style of microcontroller was selected
       when the compiler was configured; the defaults for the
       most common choices are given below.

       -m6811
       -m68hc11
           Generate output for a 68HC11.  This is the default
           when the compiler is configured for 68HC11-based sys­
           tems.

       -m6812
       -m68hc12
           Generate output for a 68HC12.  This is the default
           when the compiler is configured for 68HC12-based sys­
           tems.

       -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.

       VAX Options

       These -m options are defined for the VAX:

       -munix

       -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.  This is the default.

           To be fully SVR4 ABI compliant at the cost of some
           performance loss, specify -mno-app-regs.  You should
           compile libraries and system software with this
           option.

       -mfpu
       -mhard-float
           Generate output containing floating point instruc­
           tions.  This is the default.

       -mno-fpu
       -msoft-float
           Generate output containing library calls for floating
           point.  Warning: the requisite libraries are not
           available for all SPARC targets.  Normally the facili­
           ties 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 suit­
           able 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 com­
           pile all of a program with this option.  In particu­
           lar, 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 func­
           tions 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 han­
           dler emulates the effect of the instruction.  Because
           of the trap handler overhead, this is much slower than
           With -mno-flat (the default), the compiler emits
           save/restore instructions (except for leaf functions)
           and is the normal mode of operation.

       -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.

       -mv8
       -msparclite
           These two options select variations on the SPARC
           architecture.

           By default (unless specifically configured for the
           Fujitsu SPARClite), GCC generates code for the v7
           variant of the SPARC architecture.

           -mv8 will give you SPARC v8 code.  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.

           -msparclite will give you SPARClite code.  This adds
           the integer multiply, integer divide step and scan
           ("ffs") instructions which exist in SPARClite but not
           in SPARC v7.

           These options are deprecated and will be deleted in a
           future GCC release.  They have been replaced with
           -mcpu=xxx.
           full SPARC v8 instruction set.

           These options are deprecated and will be deleted in a
           future GCC release.  They have been replaced with
           -mcpu=xxx.

       -mcpu=cpu_type
           Set the instruction set, register set, and instruction
           scheduling parameters for machine type cpu_type.  Sup­
           ported values for cpu_type are v7, cypress, v8, super­
           sparc, sparclite, hypersparc, sparclite86x, f930,
           f934, sparclet, tsc701, v9, ultrasparc, and ultra­
           sparc3.

           Default instruction scheduling parameters are used for
           values that select an architecture and not an imple­
           mentation.  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

       -mtune=cpu_type
           Set the instruction scheduling parameters for machine
           type cpu_type, but do not set the instruction set or
           register set that 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, spar­
           clite86x, tsc701, ultrasparc, and ultrasparc3.

       These -m switches are supported in addition to the above
       on the SPARCLET processor.

       -mlittle-endian
           Generate code for a processor running in little-endian
           mode.

       -mlive-g0
           Treat register %g0 as a normal register.  GCC will
           continue to clobber it as necessary but will not
           assume it always reads as 0.

       -mbroken-saverestore
           Generate code that does not use non-trivial forms of
           Generate code for a processor running in little-endian
           mode.

       -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: the pro­
           gram must be linked in the low 32 bits of the address
           space.  Pointers are 64 bits.  Programs can be stati­
           cally or dynamically linked.

       -mcmodel=medmid
           Generate code for the Medium/Middle code model: the
           program must be linked in the low 44 bits of the
           address space, the text segment must be less than 2G
           bytes, and data segment must be within 2G of the text
           segment.  Pointers are 64 bits.

       -mcmodel=medany
           Generate code for the Medium/Anywhere code model: the
           program may be linked anywhere in the address space,
           the text segment must be less than 2G bytes, and data
           segment must be within 2G of the text segment.  Point­
           ers are 64 bits.

       -mcmodel=embmedany
           Generate code for the Medium/Anywhere code model for
           embedded systems: assume a 32-bit text and a 32-bit
           data segment, both starting anywhere (determined at
           link time).  Register %g4 points to the base of the
           data segment.  Pointers are still 64 bits.  Programs
           are statically linked, PIC is not supported.

       -mstack-bias
       -mno-stack-bias
           With -mstack-bias, GCC assumes that the stack pointer,
           and frame pointer if present, are offset by -2047
           which must be added back when making stack frame ref­
           erences.  Otherwise, assume no such offset is present.

       ARM Options

       These -m options are defined for Advanced RISC Machines
       (ARM) architectures:

       -mapcs-frame
           Generate a stack frame that is compliant with the ARM
           replaces the -m2 and -m3 options of previous releases
           of the compiler.

       -mapcs-32
           Generate code for a processor running with a 32-bit
           program counter, and conforming to the function call­
           ing standards for the APCS 32-bit option.  This option
           replaces the -m6 option of previous releases of the
           compiler.

       -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 infor­
           mation can be used to locate the start if functions
           inside an executable piece of code.  The default is
           -msched-prolog.

       -mhard-float
           Generate output containing floating point instruc­
           tions.  This is the default.

       -msoft-float
           Generate output containing library calls for floating
           point.  Warning: the requisite libraries are not
           available for all ARM targets.  Normally the facili­
           ties 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 suit­
           able library functions for cross-compilation.

           -msoft-float changes the calling convention in the
           output file; therefore, it is only useful if you com­
           pile all of a program with this option.  In particu­
           lar, you need to compile libgcc.a, the library that
           comes with GCC, with -msoft-float in order for this to
           work.

       -mlittle-endian
           Generate code for a processor running in little-endian
           mode.  This is the default for all standard configura­
           sions of the compiler prior to 2.8.

       -malignment-traps
           Generate code that will not trap if the MMU has align­
           ment traps enabled.  On ARM architectures prior to
           ARMv4, there were no instructions to access half-word
           objects stored in memory.  However, when reading from
           memory a feature of the ARM architecture allows a word
           load to be used, even if the address is unaligned, and
           the processor core will rotate the data as it is being
           loaded.  This option tells the compiler that such mis­
           aligned accesses will cause a MMU trap and that it
           should instead synthesize the access as a series of
           byte accesses.  The compiler can still use word
           accesses to load half-word data if it knows that the
           address is aligned to a word boundary.

           This option is ignored when compiling for ARM archi­
           tecture 4 or later, since these processors have
           instructions to directly access half-word objects in
           memory.

       -mno-alignment-traps
           Generate code that assumes that the MMU will not trap
           unaligned accesses.  This produces better code when
           the target instruction set does not have half-word
           memory operations (i.e. implementations prior to
           ARMv4).

           Note that you cannot use this option to access
           unaligned word objects, since the processor will only
           fetch one 32-bit aligned object from memory.

           The default setting for most targets is -mno-align­
           ment-traps, since this produces better code when there
           are no half-word memory instructions available.

       -mshort-load-bytes
       -mno-short-load-words
           These are deprecated aliases for -malignment-traps.

       -mno-short-load-bytes
       -mshort-load-words
           This are deprecated aliases for -mno-alignment-traps.

       -mcpu=name
           This specifies the name of the target ARM processor.
           GCC uses this name to determine what kind of instruc­
           tions it can emit when generating assembly code.  Per­
           missible names are: arm2, arm250, arm3, arm6, arm60,
           arm600, arm610, arm620, arm7, arm7m, arm7d, arm7dm,
           arm7di, arm7dmi, arm70, arm700, arm700i, arm710,
           mentations better performance can be obtained by using
           this option.

       -march=name
           This specifies the name of the target ARM architec­
           ture.  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, armv5te.

       -mfpe=number
       -mfp=number
           This specifies the version of the floating point emu­
           lation available on the target.  Permissible values
           are 2 and 3.  -mfp= is a synonym for -mfpe=, for com­
           patibility with older versions of GCC.

       -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 and 32.  The default
           value varies for different toolchains.  For the COFF
           targeted toolchain the default value is 8.  Specifying
           the larger number can produce faster, more efficient
           code, but can also increase the size of the program.
           The two values are potentially incompatible.  Code
           compiled with one value cannot necessarily expect to
           work with code or libraries compiled with the other
           value, if they exchange information using structures
           or unions.

       -mabort-on-noreturn
           Generate a call to the function "abort" at the end of
           a "noreturn" function.  It will be executed if the
           function tries to return.

       -mlong-calls
       -mno-long-calls
           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 regis­
           ter.  This switch is needed if the target function
           will lie outside of the 64 megabyte addressing 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
           handle function calls via function pointers.

       -mnop-fun-dllimport
           Disable support for the "dllimport" attribute.

       -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.

       -mpoke-function-name
           Write the name of each function into the text section,
           directly preceding the function prologue.  The gener­
           ated 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}
                            sub     fp, ip, #4

           When performing a stack backtrace, code can inspect
           the value of "pc" stored at "fp + 0".  If the trace
           function then looks at location "pc - 12" and the top
           8 bits are set, then we know that there is a function
           name embedded immediately preceding this location and
           has length "((pc[-3]) & 0xff000000)".

       -mthumb
           Generate code for the 16-bit Thumb instruction set.
           The default is to use the 32-bit ARM instruction set.

       -mtpcs-frame
           Generate a stack frame that is compliant with the
           Thumb Procedure Call Standard for all non-leaf func­
           tions.  (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.
           not.  There is a small overhead in the cost of execut­
           ing a function pointer if this option is enabled.

       MN10200 Options

       These -m options are defined for Matsushita MN10200 archi­
       tectures:

       -mrelax
           Indicate to the linker that it should perform a relax­
           ation 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.

       MN10300 Options

       These -m options are defined for Matsushita MN10300 archi­
       tectures:

       -mmult-bug
           Generate code to avoid bugs in the multiply instruc­
           tions for the MN10300 processors.  This is the
           default.

       -mno-mult-bug
           Do not generate code to avoid bugs in the multiply
           instructions for the MN10300 processors.

       -mam33
           Generate code which uses features specific to the AM33
           processor.

       -mno-am33
           Do not generate code which uses features specific to
           the AM33 processor.  This is the default.

       -mno-crt0
           Do not link in the C run-time initialization object
           file.

       -mrelax
           Indicate to the linker that it should perform a relax­
           ation 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.

           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.

       -mcode-model=medium
           Assume objects may be anywhere in the 32-bit address
           space (the compiler will generate "seth/add3" instruc­
           tions to load their addresses), and assume all subrou­
           tines are reachable with the "bl" instruction.

       -mcode-model=large
           Assume objects may be anywhere in the 32-bit address
           space (the compiler will generate "seth/add3" instruc­
           tions to load their addresses), and assume subroutines
           may not be reachable with the "bl" instruction (the
           compiler will generate the much slower "seth/add3/jl"
           instruction sequence).

       -msdata=none
           Disable use of the small data area.  Variables will be
           put into one of .data, bss, or .rodata (unless the
           "section" attribute has been specified).  This is the
           default.

           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.

       -m88110
           Generate code that works best for the m88110, and may
           not run on the m88100.

       -mbig-pic
           Obsolete option to be removed from the next revision.
           Use -fPIC.

       -midentify-revision
           Include an "ident" directive in the assembler output
           recording the source file name, compiler name and ver­
           sion, timestamp, and compilation flags used.

       -mno-underscores
           In assembler output, emit symbol names without adding
           an underscore character at the beginning of each name.
           The default is to use an underscore as prefix on each
           name.

       -mocs-debug-info
       -mno-ocs-debug-info
           Include (or omit) additional debugging information
           (about registers used in each stack frame) as speci­
           fied in the 88open Object Compatibility Standard,
           ``OCS''.  This extra information allows debugging of
           code that has had the frame pointer eliminated.  The
           default for SVr4 and Delta 88 SVr3.2 is to include
           this information; other 88k configurations omit this
           information by default.

       -mocs-frame-position
           When emitting COFF debugging information for automatic
           variables and parameters stored on the stack, use the
           offset from the canonical frame address, which is the
           stack pointer (register 31) on entry to the function.
           The SVr4 and Delta88 SVr3.2, and BCS configurations
           use -mocs-frame-position; other 88k configurations
           have the default -mno-ocs-frame-position.

       -mno-ocs-frame-position
           When emitting COFF debugging information for automatic
           variables and parameters stored on the stack, use the
           offset from the frame pointer register (register 30).
           When this option is in effect, the frame pointer is
           not eliminated when debugging information is selected
           by the -g switch.

       -moptimize-arg-area
           Save space by reorganizing the stack frame.  This
           option generates code that does not agree with the
           88open specifications, but uses less memory.

           greater than 64k.

       -mserialize-volatile
       -mno-serialize-volatile
           Do, or don't, generate code to guarantee sequential
           consistency of volatile memory references.  By
           default, consistency is guaranteed.

           The order of memory references made by the MC88110
           processor does not always match the order of the
           instructions requesting those references.  In particu­
           lar, a load instruction may execute before a preceding
           store instruction.  Such reordering violates sequen­
           tial consistency of volatile memory references, when
           there are multiple processors.   When consistency must
           be guaranteed, GCC generates special instructions, as
           needed, to force execution in the proper order.

           The MC88100 processor does not reorder memory refer­
           ences and so always provides sequential consistency.
           However, by default, GCC generates the special
           instructions to guarantee consistency even when you
           use -m88100, so that the code may be run on an MC88110
           processor.  If you intend to run your code only on the
           MC88100 processor, you may use -mno-serial­
           ize-volatile.

           The extra code generated to guarantee consistency may
           affect the performance of your application.  If you
           know that you can safely forgo this guarantee, you may
           use -mno-serialize-volatile.

       -msvr4
       -msvr3
           Turn on (-msvr4) or off (-msvr3) compiler extensions
           related to System V release 4 (SVr4).  This controls
           the following:

           1.  Which variant of the assembler syntax to emit.

           2.  -msvr4 makes the C preprocessor recognize #pragma
               weak that is used on System V release 4.

           3.  -msvr4 makes GCC issue additional declaration
               directives used in SVr4.

           -msvr4 is the default for the m88k-motorola-sysv4 con­
           figuration.  -msvr3 is the default for all other m88k
           configurations.

       -mversion-03.00
           This option is obsolete, and is ignored.
           code generated to run on an MC88100 processor.

           GCC assumes that the MC88110 processor correctly
           detects all instances of integer division by zero.
           When -m88110 is specified, no explicit checks for
           zero-valued divisors are generated, and both
           -mcheck-zero-division and -mno-check-zero-division are
           ignored.

       -muse-div-instruction
           Use the div instruction for signed integer division on
           the MC88100 processor.  By default, the div instruc­
           tion is not used.

           On the MC88100 processor the signed integer division
           instruction div) traps to the operating system on a
           negative operand.  The operating system transparently
           completes the operation, but at a large cost in execu­
           tion time.  By default, when compiling code that might
           be run on an MC88100 processor, GCC emulates signed
           integer division using the unsigned integer division
           instruction divu), thereby avoiding the large penalty
           of a trap to the operating system.  Such emulation has
           its own, smaller, execution cost in both time and
           space.  To the extent that your code's important
           signed integer division operations are performed on
           two nonnegative operands, it may be desirable to use
           the div instruction directly.

           On the MC88110 processor the div instruction (also
           known as the divs instruction) processes negative
           operands without trapping to the operating system.
           When -m88110 is specified, -muse-div-instruction is
           ignored, and the div instruction is used for signed
           integer division.

           Note that the result of dividing "INT_MIN" by -1 is
           undefined.  In particular, the behavior of such a
           division with and without -muse-div-instruction may
           differ.

       -mtrap-large-shift
       -mhandle-large-shift
           Include code to detect bit-shifts of more than 31
           bits; respectively, trap such shifts or emit code to
           handle them properly.  By default GCC makes no special
           provision for large bit shifts.

       -mwarn-passed-structs
           Warn when a function passes a struct as an argument or
           result.  Structure-passing conventions have changed
           during the evolution of the C language, and are often

       -mpowerpc-gpopt
       -mno-powerpc-gpopt
       -mpowerpc-gfxopt
       -mno-powerpc-gfxopt
       -mpowerpc64
       -mno-powerpc64
           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 Pow­
           erPC instruction set is the architecture of the
           Motorola MPC5xx, MPC6xx, MPC8xx microprocessors, and
           the IBM 4xx microprocessors.

           Neither architecture is a subset of the other.  How­
           ever there is a large common subset of instructions
           supported by both.  An MQ register is included in pro­
           cessors supporting the POWER architecture.

           You use these options to specify which instructions
           are available on the processor you are using.  The
           default value of these options is determined when con­
           figuring GCC.  Specifying the -mcpu=cpu_type overrides
           the specification of these options.  We recommend you
           use the -mcpu=cpu_type option rather than the options
           listed above.

           The -mpower option allows GCC to generate instructions
           that are found only in the POWER architecture and to
           use the MQ register.  Specifying -mpower2 implies
           -power and also allows GCC to generate instructions
           that are present in the POWER2 architecture but not
           the original POWER architecture.

           The -mpowerpc option allows GCC to generate instruc­
           tions that are found only in the 32-bit subset of the
           PowerPC architecture.  Specifying -mpowerpc-gpopt
           implies -mpowerpc and also allows GCC to use the
           optional PowerPC architecture instructions in the Gen­
           eral Purpose group, including floating-point square
           root.  Specifying -mpowerpc-gfxopt implies -mpowerpc
           and also allows GCC to use the optional PowerPC archi­
           tecture instructions in the Graphics group, including
           floating-point select.

           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
           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 some­
           times overrides the value of these option.  Unless you
           are building a cross-compiler, you should normally not
           specify either -mnew-mnemonics or -mold-mnemonics, but
           should instead accept the default.

       -mcpu=cpu_type
           Set architecture type, register usage, choice of
           mnemonics, and instruction scheduling parameters for
           machine type cpu_type.  Supported values for cpu_type
           are rios, rios1, rsc, rios2, rs64a, 601, 602, 603,
           603e, 604, 604e, 620, 630, 740, 7400, 7450, 750,
           power, power2, powerpc, 403, 505, 801, 821, 823, and
           860 and common.

           -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 instruc­
           tions 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 pur­
           poses.

           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
           other -m options as follows:

           common
               -mno-power, -mno-powerpc

           power
           power2
           rios1
           rios2
           rsc -mpower, -mno-powerpc, -mno-new-mnemonics

           powerpc

           403
           821
           860 -mno-power, -mpowerpc, -mnew-mnemonics,
               -msoft-float

       -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 speci­
           fied, the code generated will use the architecture,
           registers, and mnemonics set by -mcpu, but the
           scheduling parameters set by -mtune.

       -maltivec
       -mno-altivec
           These switches enable or disable the use of built-in
           functions that allow access to the AltiVec instruction
           set.  You may also need to set -mabi=altivec to adjust
           the current ABI with AltiVec ABI enhancements.

       -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.

       -mabi=no-spe
           Disable Booke SPE ABI extensions for the current ABI.

       -misel=yes/no
       -misel
           This switch enables or disables the generation of ISEL
           instructions.

       -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 avail­
           able 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
           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.  Specifying -maix64 implies
           -mpowerpc64 and -mpowerpc, while -maix32 disables the
           64-bit ABI and implies -mno-powerpc64.  GCC defaults
           to -maix32.

       -mxl-call
       -mno-xl-call
           On AIX, pass floating-point arguments to prototyped
           functions beyond the register save area (RSA) on the
           stack in addition to argument FPRs.  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.  AIX 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 AIX
           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 stan­
           dard 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.

       -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.

       -mmultiple
       -mno-multiple
           Generate code that uses (does not use) the load multi­
           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.

       -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.

       -mno-bit-align
       -mbit-align
           On System V.4 and embedded PowerPC systems do not (do)
           force structures and unions that contain bit-fields to
           be aligned to the base type of the bit-field.

           For example, by default a structure containing nothing
           but 8 "unsigned" bit-fields of length 1 would be
           aligned to a 4 byte boundary and have a size of 4
           bytes.  By using -mno-bit-align, the structure would
           be aligned to a 1 byte boundary and be one byte in
           size.

       -mno-strict-align
       -mstrict-align
           On System V.4 and embedded PowerPC systems do not (do)
           assume that unaligned memory references will be han­
           dled by the system.

       -mrelocatable
       -mno-relocatable
           On embedded PowerPC systems generate code that allows
           (does not allow) the program to be relocated to a dif­
           ferent address at runtime.  If you use -mrelocatable
           on any module, all objects linked together must be
           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.

       -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 pow­
           erpc-*-eabiaix.

       -mcall-sysv-eabi
           Specify both -mcall-sysv and -meabi options.

       -mcall-sysv-noeabi
           Specify both -mcall-sysv and -mno-eabi options.

       -mcall-aix
           On System V.4 and embedded PowerPC systems compile
           code using calling conventions that are similar to
           those used on AIX.  This is the default if you config­
           ured GCC using powerpc-*-eabiaix.

       -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.

           Disable AltiVec ABI extensions for the current ABI.

       -mprototype
       -mno-prototype
           On System V.4 and embedded PowerPC systems assume that
           all calls to 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.

       -mwindiss
           Specify that you are compiling for the WindISS simula­
           tion environment.

       -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)

       -msdata=eabi
           On System V.4 and embedded PowerPC systems, put small
           initialized "const" global and static data in the
           .sdata2 section, which is pointed to by register "r2".
           Put small initialized non-"const" global and static
           data in the .sdata section, which is pointed to by
           register "r13".  Put small uninitialized global and
           static data in the .sbss section, which is adjacent to
           the .sdata section.  The -msdata=eabi option is incom­
           patible with the -mrelocatable option.  The
           -msdata=eabi option also sets the -memb option.

       -msdata=sysv
           On System V.4 and embedded PowerPC systems, put small
           global and static data in the .sdata section, which is
           pointed to by register "r13".  Put small uninitialized
           global and static data in the .sbss section, which is
           adjacent to the .sdata section.  The -msdata=sysv
           option is incompatible with the -mrelocatable option.

       -msdata=default
       -msdata
           On System V.4 and embedded PowerPC systems, if -meabi
           is used, compile code the same as -msdata=eabi, other­
           wise compile code the same as -msdata=sysv.

       -msdata-data
           On System V.4 and embedded PowerPC systems, put small
           global and static data in the .sdata section.  Put
           small uninitialized global and static 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 com­
           piled 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
           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.

           In the future, we may cause GCC to ignore all longcall
           specifications when the linker is known to generate
           glue.

       -pthread
           Adds support for multithreading with the pthreads
           library.  This option sets flags for both the prepro­
           cessor and linker.

       Darwin Options

       -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 specifies the executable that will be loading the
           build output file being linked. See man ld(1) for more
           information.

       -allowable_client  client_name
       -arch_only
       -client_name
       -compatibility_version
       -current_version
       -dependency-file
       -dylib_file
       -dylinker_install_name
       -dynamic
       -dynamiclib
       -exported_symbols_list
       -filelist
       -flat_namespace
       -force_cpusubtype_ALL
       -force_flat_namespace
       -prebind_all_twolevel_modules
       -private_bundle
       -read_only_relocs
       -sectalign
       -sectobjectsymbols
       -whyload
       -seg1addr
       -sectcreate
       -sectobjectsymbols
       -sectorder
       -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
           This options are available for Darwin linker. Darwin
           linker man page describes them in detail.

       IBM RT Options

       These -m options are defined for the IBM RT PC:

       -min-line-mul
           Use an in-line code sequence for integer multiplies.
           This is the default.

       -mcall-lib-mul
           Call "lmul$$" for integer multiples.

       -mfull-fp-blocks
           Generate full-size floating point data blocks, includ­
           ing the minimum amount of scratch space recommended by
           IBM.  This is the default.

       -mminimum-fp-blocks
           Do not include extra scratch space in floating point
           data blocks.  This results in smaller code, but slower
           execution, since scratch space must be allocated
           dynamically.

       -mfp-arg-in-fpregs
           option -fpcc-struct-return for compatibility with the
           Portable C Compiler (pcc).

       -mnohc-struct-return
           Return some structures of more than one word in regis­
           ters, when convenient.  This is the default.  For com­
           patibility with the IBM-supplied compilers, use the
           option -fpcc-struct-return or the option
           -mhc-struct-return.

       MIPS Options

       These -m options are defined for the MIPS family of com­
       puters:

       -march=arch
           Generate code that will run on arch, which can be the
           name of a generic MIPS ISA, or the name of a particu­
           lar processor.  The ISA names are: mips1, mips2,
           mips3, mips4, mips32 and mips64.  The processor names
           are: r2000, r3000, r3900, r4000, vr4100, vr4300,
           r4400, r4600, r4650, vr5000, r6000, r8000, 4kc, 4kp,
           5kc, 20kc, orion, and sb1.  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).

           In processor names, a final 000 can be abbreviated as
           k (for example, -march=r2k).  Prefixes are optional,
           and vr may be written r.

           GCC defines two macros based on the value of this
           option.  The first is _MIPS_ARCH, which gives the name
           of target architecture, as a string.  The second has
           the form _MIPS_ARCH_foo, where foo is the capitalized
           value of _MIPS_ARCH.  For example, -march=r2000 will
           set _MIPS_ARCH to "r2000" and define the macro
           _MIPS_ARCH_R2000.

           Note that the _MIPS_ARCH macro uses the processor
           names given above.  In other words, it will have the
           full prefix and will not abbreviate 000 as k.  In the
           case of from-abi, the macro names the resolved archi­
           tecture (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.

           Equivalent to -march=mips2.

       -mips3
           Equivalent to -march=mips3.

       -mips4
           Equivalent to -march=mips4.

       -mips32
           Equivalent to -march=mips32.

       -mips64
           Equivalent to -march=mips64.

       -mfused-madd
       -mno-fused-madd
           Generate code that uses (does not use) the floating
           point multiply and accumulate instructions, when they
           are available.  These instructions are generated by
           default if they are available, but this may be unde­
           sirable if the extra precision causes problems or on
           certain chips in the mode where denormals are rounded
           to zero where denormals generated by multiply and
           accumulate instructions cause exceptions anyway.

       -mfp32
           Assume that floating point registers are 32 bits wide.

       -mfp64
           Assume that floating point registers are 64 bits wide.

       -mgp32
           Assume that general purpose registers are 32 bits
           wide.

       -mgp64
           Assume that general purpose registers are 64 bits
           wide.

       -mint64
           Force int and long types to be 64 bits wide.  See
           -mlong32 for an explanation of the default, and the
           width of pointers.

       -mlong64
           Force long types to be 64 bits wide.  See -mlong32 for
           an explanation of the default, and the width of point­
           ers.

       -mlong32
           Force long, int, and pointer types to be 32 bits wide.


           Note that there are two embedded ABIs: -mabi=eabi
           selects the one defined by Cygnus while -meabi=meabi
           selects the one defined by MIPS.  Both these ABIs have
           32-bit and 64-bit variants.  Normally, GCC will gener­
           ate 64-bit code when you select a 64-bit architecture,
           but you can use -mgp32 to get 32-bit code instead.

       -mmips-as
           Generate code for the MIPS assembler, and invoke mips-
           tfile to add normal debug information.  This is the
           default for all platforms except for the OSF/1 refer­
           ence platform, using the OSF/rose object format.  If
           the either of the -gstabs or -gstabs+ switches are
           used, the mips-tfile program will encapsulate the
           stabs within MIPS ECOFF.

       -mgas
           Generate code for the GNU assembler.  This is the
           default on the OSF/1 reference platform, using the
           OSF/rose object format.  Also, this is the default if
           the configure option --with-gnu-as is used.

       -msplit-addresses
       -mno-split-addresses
           Generate code to load the high and low parts of
           address constants separately.  This allows GCC to
           optimize away redundant loads of the high order bits
           of addresses.  This optimization requires GNU as and
           GNU ld.  This optimization is enabled by default for
           some embedded targets where GNU as and GNU ld are
           standard.

       -mrnames
       -mno-rnames
           The -mrnames switch says to output code using the MIPS
           software names for the registers, instead of the hard­
           ware names (ie, a0 instead of $4).  The only known
           assembler that supports this option is the Algorith­
           mics assembler.

       -mgpopt
       -mno-gpopt
           The -mgpopt switch says to write all of the data dec­
           larations before the instructions in the text section,
           this allows the MIPS assembler to generate one word
           memory references instead of using two words for short
           global or static data items.  This is on by default if
           optimization is selected.

       -mstats
       -mno-stats
           postprocess the object file with the mips-tfile pro­
           gram, after the MIPS assembler has generated it to add
           debug support.  If mips-tfile is not run, then no
           local variables will be available to the debugger.  In
           addition, stage2 and stage3 objects will have the tem­
           porary file names passed to the assembler embedded in
           the object file, which means the objects will not com­
           pare the same.  The -mno-mips-tfile switch should only
           be used when there are bugs in the mips-tfile program
           that prevents compilation.

       -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 own
           arrangements to provide suitable library functions for
           cross-compilation.

       -mhard-float
           Generate output containing floating point instruc­
           tions.  This is the default if you use the unmodified
           sources.

       -mabicalls
       -mno-abicalls
           Emit (or do not emit) the pseudo operations .abicalls,
           .cpload, and .cprestore that some System V.4 ports use
           for position independent code.

       -mlong-calls
       -mno-long-calls
           Do all calls with the JALR instruction, which requires
           loading up a function's address into a register before
           the call.  You need to use this switch, if you call
           outside of the current 512 megabyte segment to func­
           tions that are not through pointers.

       -mhalf-pic
       -mno-half-pic
           Put pointers to extern references into the data sec­
           tion and load them up, rather than put the references
           in the text section.

       -membedded-pic
       -mno-embedded-pic
           Generate PIC code suitable for some embedded systems.
           All calls are made using PC relative address, and all
           data is addressed using the $gp register.  No more
           than 65536 bytes of global data may be used.  This
           requires GNU as and GNU ld which do most of the work.
           When used together with -membedded-data, it will
           always store uninitialized const variables in the
           read-only data section.

       -msingle-float
       -mdouble-float
           The -msingle-float switch tells gcc to assume that the
           floating point coprocessor only supports single preci­
           sion operations, as on the r4650 chip.  The -mdou­
           ble-float switch permits gcc to use double precision
           operations.  This is the default.

       -mmad
       -mno-mad
           Permit use of the mad, madu and mul instructions, as
           on the r4650 chip.

       -m4650
           Turns on -msingle-float, -mmad, and, at least for now,
           -mcpu=r4650.

       -mips16
       -mno-mips16
           Enable 16-bit instructions.

       -mentry
           Use the entry and exit pseudo ops.  This option can
           only be used with -mips16.

       -EL Compile code for the processor in little endian mode.
           The requisite libraries are assumed to exist.

       -EB Compile code for the processor in big endian mode.
           The requisite libraries are assumed to exist.

       -G num
           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.  This allows the
           assembler to emit one word memory reference instruc­
           tions based on the global pointer (gp or $28), instead
           of the normal two words used.  By default, num is 8
           when the MIPS assembler is used, and 0 when the GNU
           assembler is used.  The -G num switch is also passed
           to the assembler and linker.  All modules should be
           compiled with the same -G num value.

       -nocpp
           Tell the MIPS assembler to not run its preprocessor
           over user assembler files (with a .s suffix) when
           assembling them.

           mon "_flush_func()", that is, the address of the mem­
           ory 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-likely
       -mno-branch-likely
           Enable or disable use of Branch Likely instructions,
           regardless of the default for the selected architec­
           ture.  By default, Branch Likely instructions may be
           generated if they are supported by the selected archi­
           tecture.  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.

       Intel 386 and AMD x86-64 Options

       These -m options are defined for the i386 and x86-64 fam­
       ily of computers:

       -mcpu=cpu-type
           Tune to cpu-type everything applicable about the gen­
           erated code, except for the ABI and the set of avail­
           able instructions.  The choices for cpu-type are i386,
           i486, i586, i686, pentium, pentium-mmx, pentiumpro,
           pentium2, pentium3, pentium4, k6, k6-2, k6-3, athlon,
           athlon-tbird, athlon-4, athlon-xp, athlon-mp,
           winchip-c6, winchip2 and c3.

           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.
           i586 is equivalent to pentium and i686 is equivalent
           to pentiumpro.  k6 and athlon are the AMD chips as
           opposed to the Intel ones.

       -march=cpu-type
           Generate instructions for the machine type cpu-type.
           The choices for cpu-type are the same as for -mcpu.
           Moreover, specifying -march=cpu-type implies
           -mcpu=cpu-type.

       -m386
       -m486
       -mpentium
       -mpentiumpro
               compared to 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 sup­
               ports 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 i387 you need to use -march=cpu-type, -msse or
               -msse2 switches to enable SSE extensions and make
               this option effective.  For x86-64 compiler, these
               extensions are enabled by default.

               The resulting code should be considerably faster
               in 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 x86-64 compiler.

           sse,387
               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 experi­
               mental, because gcc register allocator does not
               model separate functional units well resulting in
               instable performance.

       -masm=dialect
           Output asm instructions using selected dialect. Sup­
           ported choices are intel or att (the default one).

       -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

           The usual calling convention has functions return val­
           ues of types "float" and "double" in an FPU register,
           even if there is no FPU.  The idea is that the operat­
           ing system should emulate an FPU.

           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 instruc­
           tion 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.

           Warning: if you use the -malign-double switch, struc­
           tures containing the above types will be aligned dif­
           ferently than the published application binary inter­
           face specifications for the 386 and will not be binary
           compatible with structures in code compiled without
           that switch.

       -m128bit-long-double
           Control the size of "long double" type. i386 applica­
           tion binary interface specify the size to be 12 bytes,
           while modern architectures (Pentium and newer) prefer
           "long double" aligned to 8 or 16 byte boundary.  This
           is impossible to reach with 12 byte long doubles in
           the array accesses.

           Warning: if you use the -m128bit-long-double switch,
           the structures and arrays containing "long double"
           will change their size as well as function calling
           convention for function taking "long double" will be
           modified.

       -m96bit-long-double
           Set the size of "long double" to 96 bits as required
           by the i386 application binary interface.  This is the
           the caller since there is no need to pop the arguments
           there.

           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 com­
           piler.

           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.  (Nor­
           mally, 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.

       -mpreferred-stack-boundary=num
           Attempt to keep the stack boundary aligned to a 2
           raised to num byte boundary.  If -mpre­
           ferred-stack-boundary is not specified, the default is
           4 (16 bytes or 128 bits), except when optimizing for
           code size (-Os), in which case the default is the min­
           imum correct alignment (4 bytes for x86, and 8 bytes
           for x86-64).

           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 perfor­
           mance penalties.  On Pentium III, the Streaming SIMD
           Extension (SSE) data type "__m128" suffers similar
           penalties 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

       -mmmx
       -mno-mmx
       -msse
       -mno-sse
       -msse2
       -mno-sse2
       -m3dnow
       -mno-3dnow
           These switches enable or disable the use of built-in
           functions that allow direct access to the MMX, SSE and
           3Dnow extensions of the instruction set.

           To have SSE/SSE2 instructions generated automatically
           from floating-point code, see -mfpmath=sse.

       -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 per­
           formance because of improved scheduling and reduced
           dependencies.

       -maccumulate-outgoing-args
           If enabled, the maximum amount of space required for
           outgoing arguments will be computed in the function
           prologue.  This is faster on most modern CPUs because
           of reduced dependencies, improved scheduling and
           reduced stack usage when preferred stack boundary is
           not equal to 2.  The drawback is a notable increase in
           code size.  This switch implies -mno-push-args.

       -mthreads
           Support thread-safe exception handling on Mingw32.
           Code that relies on thread-safe exception handling
           must compile and link all code with the -mthreads
           option.  When compiling, -mthreads defines -D_MT; when
           linking, it links in a special thread helper library
           -lmingwthrd which cleans up per thread exception han­
           dling 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
           don'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

       -m32
       -m64
           Generate code for a 32-bit or 64-bit environment.  The
           32-bit environment sets int, long and pointer to 32
           bits and generates code that runs on any i386 system.
           The 64-bit environment sets int to 32 bits and long
           and pointer to 64 bits and generates code for AMD's
           x86-64 architecture.

       -mno-red-zone
           Do not use a so called red zone for x86-64 code.  The
           red zone is mandated by the x86-64 ABI, it is a
           128-byte area beyond the location of the stack pointer
           that will not be modified by signal or interrupt han­
           dlers and therefore can be used for temporary data
           without adjusting the stack pointer.  The flag
           -mno-red-zone 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 but sym­
           bols can be located anywhere in the address space.
           Programs can be statically or dynamically linked, but
           building of shared libraries are not supported with
           the medium model.

       -mcmodel=large
           Generate code for the large model: This model makes no
           assumptions about addresses and sizes of sections.
           Currently GCC does not implement this model.

       HPPA Options

       These -m options are defined for the HPPA family of com­
       puters:

       -march=architecture-type
           Generate code for the specified architecture.  The
           choices for architecture-type are 1.0 for PA 1.0, 1.1
           Synonyms for -march=1.0, -march=1.1, and -march=2.0
           respectively.

       -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.

       -mjump-in-delay
           Fill delay slots of function calls with unconditional
           jump instructions by modifying the return pointer for
           the function call to be the target of the conditional
           jump.

       -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 per­
           form 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 indi­
           rect calls and use unscaled index address modes.

           Such code is suitable for level 0 PA systems and ker­
           nels.

       -mfast-indirect-calls
           Generate code that assumes calls never cross space
           boundaries.  This allows GCC to emit code which per­
           forms faster indirect calls.

           This option will not work in the presence of shared
           libraries or nested functions.

       -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.

           Note this makes symbolic debugging impossible.  It
           also triggers a bug in the HP-UX 8 and HP-UX 9 linkers
           in which they give bogus error messages when linking
           some programs.

       -msoft-float
           Generate output containing library calls for floating
           point.  Warning: the requisite libraries are not
           available for all HPPA targets.  Normally the facili­
           ties 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 suit­
           able library functions for cross-compilation.  The
           embedded target hppa1.1-*-pro does provide software
           floating point support.

           -msoft-float changes the calling convention in the
           output file; therefore, it is only useful if you com­
           pile all of a program with this option.  In particu­
           lar, 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`.

       -mhp-ld
           Use HP ld specific options.  This passes -b to ld when
           building a shared library and passes +Accept TypeMis­
           match 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 deter­
           mined by the --with-ld configure option, gcc's program
           search path, and finally by the user's PATH.  The

           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 performance.  However, it may be useful
           in large applications, particularly when partial link­
           ing is used to build the application.

           The types of long calls used depends on the capabili­
           ties of the assembler and linker, and the type of code
           being generated.  The impact on systems that support
           long absolute calls, and long pic symbol-difference or
           pc-relative calls should be relatively small.  How­
           ever, an indirect call is used on 32-bit ELF systems
           in pic code and it is quite long.

       Intel 960 Options

       These -m options are defined for the Intel 960 implementa­
       tions:

       -mcpu-type
           Assume the defaults for the machine type cpu-type for
           some of the other options, including instruction
           scheduling, floating point support, and addressing
           modes.  The choices for cpu-type are ka, kb, mc, ca,
           cf, sa, and sb.  The default is kb.

       -mnumerics
       -msoft-float
           The -mnumerics option indicates that the processor
           does support floating-point instructions.  The
           -msoft-float option indicates that floating-point sup­
           port should not be assumed.

       -mleaf-procedures
       -mno-leaf-procedures
           Do (or do not) attempt to alter leaf procedures to be
           callable with the "bal" instruction as well as "call".
           This will result in more efficient code for explicit
           calls when the "bal" instruction can be substituted by
           the assembler or linker, but less efficient code in
           other cases, such as calls via function pointers, or
           using a linker that doesn't support this optimization.

       -mtail-call
       -mno-tail-call
           Do (or do not) make additional attempts (beyond those
           of the machine-independent portions of the compiler)

       -mcode-align
       -mno-code-align
           Align code to 8-byte boundaries for faster fetching
           (or don't bother).  Currently turned on by default for
           C-series implementations only.

       -mic-compat
       -mic2.0-compat
       -mic3.0-compat
           Enable compatibility with iC960 v2.0 or v3.0.

       -masm-compat
       -mintel-asm
           Enable compatibility with the iC960 assembler.

       -mstrict-align
       -mno-strict-align
           Do not permit (do permit) unaligned accesses.

       -mold-align
           Enable structure-alignment compatibility with Intel's
           gcc release version 1.3 (based on gcc 1.37).  This
           option implies -mstrict-align.

       -mlong-double-64
           Implement type long double as 64-bit floating point
           numbers.  Without the option long double is imple­
           mented by 80-bit floating point numbers.  The only
           reason we have it because there is no 128-bit long
           double support in fp-bit.c yet.  So it is only useful
           for people using soft-float targets.  Otherwise, we
           should recommend against use of it.

       DEC Alpha Options

       These -m options are defined for the DEC Alpha implementa­
       tions:

       -mno-soft-float
       -msoft-float
           Use (do not use) the hardware floating-point instruc­
           tions 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 float­
           ing-point operations, or compiled in such a way as to
           call such emulations routines, these routines will
           issue floating-point operations.   If you are compil­
           ing for an Alpha without floating-point operations,
           you must ensure that the library is built so as not to
           call them.

           by code compiled with -mno-fp-regs must also be com­
           piled with that option.

           A typical use of this option is building a kernel that
           does not use, and hence need not save and restore, any
           floating-point registers.

       -mieee
           The Alpha architecture implements floating-point hard­
           ware optimized for maximum performance.  It is mostly
           compliant with the IEEE floating point standard.  How­
           ever, for full compliance, software assistance is
           required.  This option generates code fully IEEE com­
           pliant code except that the inexact-flag is not main­
           tained (see below).  If this option is turned on, the
           preprocessor macro "_IEEE_FP" is defined during compi­
           lation.  The resulting code is 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 su, but the instructions are marked to be
               safe for software completion (see Alpha architec­
               ture manual for details).

           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 architec­
               ture reference manual) controls the rounding mode
               in effect.  The C library initializes this regis­
               ter for rounding towards plus infinity.  Thus,
               unless your program modifies the fpcr, d corre­
               sponds to round towards plus infinity.

       -mtrap-precision=trap-precision
           In the Alpha architecture, floating point traps are
           imprecise.  This means without software assistance it
           is impossible to recover from a floating trap and pro­
           gram execution normally needs to be terminated.  GCC
           can generate code that can assist operating system
           trap handlers in determining the exact location that
           caused a floating point trap.  Depending on the
           requirements of an application, different levels of
           precisions can be selected:

           p   Program precision.  This option is the default and
               means a trap handler can only identify which pro­
               gram caused a floating point exception.

           f   Function precision.  The trap handler can deter­
               mine 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 confor­
           mant.  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
           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.

       -mfloat-vax
       -mfloat-ieee
           Generate code that uses (does not use) VAX F and G
           floating point arithmetic instead of IEEE single and
           double precision.

       -mexplicit-relocs
       -mno-explicit-relocs
           Older Alpha assemblers provided no way to generate
           symbol relocations except via assembler macros.  Use
           of these macros does not allow optimal instruction
           scheduling.  GNU binutils as of version 2.12 supports
           a new syntax that allows the compiler to explicitly
           mark which relocations should apply to which instruc­
           tions.  This option is mostly useful for debugging, as
           GCC detects the capabilities of the assembler when it
           is built and sets 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 reloca­
           tions off of the $gp register.  This limits the size
           of the small data area to 64KB, but allows the vari­
           ables to be directly accessed via a single instruc­
           tion.

           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.

           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
           21164a
               Schedules as an EV5 and supports the BWX exten­
               sion.

           pca56
           21164pc
           21164PC
               Schedules as an EV5 and supports the BWX and MAX
               extensions.

           ev6
           21264
               Schedules as an EV6 and supports the BWX, FIX, and
               MAX extensions.

           ev67
           21264a
               Schedules as an EV6 and supports the BWX, CIX,
               FIX, and MAX extensions.

       -mtune=cpu_type
           Set only the instruction scheduling parameters for
           machine type cpu_type.  The instruction set is not
           changed.

       -mmemory-latency=time
           Sets the latency the scheduler should assume for typi­
           cal 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.


       -mvms-return-codes
           Return VMS condition codes from main.  The default is
           to return POSIX style condition (e.g. error) codes.

       H8/300 Options

       These -m options are defined for the H8/300 implementa­
       tions:

       -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 bound­
           aries.  This option has no effect on the H8/300.

       SH Options

       These -m options are defined for the SH implementations:

       -m1 Generate code for the SH1.

       -m2 Generate code for the SH2.

       -m3 Generate code for the SH3.

       -m3e
           Generate code for the SH3e.

       -m4-nofpu
           Generate code for the SH4 without a floating-point
           unit.

       -mdalign
           Align doubles at 64-bit boundaries.  Note that this
           changes the calling conventions, and thus some func­
           tions 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.

       -mfmovd
           Enable the use of the instruction "fmovd".

       -mhitachi
           Comply with the calling conventions defined by
           Hitachi.

       -mnomacsave
           Mark the "MAC" register as call-clobbered, even if
           -mhitachi is given.

       -mieee
           Increase IEEE-compliance of floating-point code.

       -misize
           Dump instruction size and location in the assembly
           code.

       -mpadstruct
           This option is deprecated.  It pads structures to mul­
           tiple of 4 bytes, which is incompatible with the SH
           ABI.

       -mspace
           Optimize for space instead of speed.  Implied by -Os.

       -mprefergot
           When generating position-independent code, emit func­
           tion calls using the Global Offset Table instead of
           the Procedure Linkage Table.

       -musermode
           Generate a library function call to invalidate
           instruction cache entries, after fixing up a trampo­
           line.  This library function call doesn't assume it
           can write to the whole memory address space.  This is
           the default when the target is "sh-*-linux*".
           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.

       TMS320C3x/C4x Options

       These -m options are defined for TMS320C3x/C4x implementa­
       tions:

       -mcpu=cpu_type
           Set the instruction set, register set, and instruction
           scheduling parameters for machine type cpu_type.  Sup­
           ported values for cpu_type are c30, c31, c32, c40, and
           c44.  The default is c40 to generate code for the
           TMS320C40.

       -mbig-memory
       -mbig
       -msmall-memory
       -msmall
           Generates code for the big or small memory model.  The
           small memory model assumed that all data fits into one
           64K word page.  At run-time the data page (DP) regis­
           ter must be set to point to the 64K page containing
           the .bss and .data program sections.  The big memory
           model is the default and requires reloading of the DP
           register for every direct memory access.

       -mbk
       -mno-bk
           Allow (disallow) allocation of general integer
           operands into the block count register BK.

       -mdb
       -mno-db
           Enable (disable) generation of code using decrement
           and branch, DBcond(D), instructions.  This is enabled
           by default for the C4x.  To be on the safe side, this
           is disabled for the C3x, since the maximum iteration
           count on the C3x is 2^{23 + 1} (but who iterates loops
           more than 2^{23} times on the C3x?).  Note that GCC
           will try to reverse a loop so that it can utilize the
           decrement and branch instruction, but will give up if
           there is more than one memory reference in the loop.
           Thus a loop where the loop counter is decremented can
           generate slightly more efficient code, in cases where
           ger multiplies instead of a library call to guarantee
           32-bit results.  Note that if one of the operands is a
           constant, then the multiplication will be performed
           using shifts and adds.  If the -mmpyi option is not
           specified for the C3x, then squaring operations are
           performed inline instead of a library call.

       -mfast-fix
       -mno-fast-fix
           The C3x/C4x FIX instruction to convert a floating
           point value to an integer value chooses the nearest
           integer less than or equal to the floating point value
           rather than to the nearest integer.  Thus if the
           floating point number is negative, the result will be
           incorrectly truncated an additional code is necessary
           to detect and correct this case.  This option can be
           used to disable generation of the additional code
           required to correct the result.

       -mrptb
       -mno-rptb
           Enable (disable) generation of repeat block sequences
           using the RPTB instruction for zero overhead looping.
           The RPTB construct is only used for innermost loops
           that do not call functions or jump across the loop
           boundaries.  There is no advantage having nested RPTB
           loops due to the overhead required to save and restore
           the RC, RS, and RE registers.  This is enabled by
           default with -O2.

       -mrpts=count
       -mno-rpts
           Enable (disable) the use of the single instruction
           repeat instruction RPTS.  If a repeat block contains a
           single instruction, and the loop count can be guaran­
           teed to be less than the value count, GCC will emit a
           RPTS instruction instead of a RPTB.  If no value is
           specified, then a RPTS will be emitted even if the
           loop count cannot be determined at compile time.  Note
           that the repeated instruction following RPTS does not
           have to be reloaded from memory each iteration, thus
           freeing up the CPU buses for operands.  However, since
           interrupts are blocked by this instruction, it is dis­
           abled by default.

       -mloop-unsigned
       -mno-loop-unsigned
           The maximum iteration count when using RPTS and RPTB
           (and DB on the C40) is 2^{31 + 1} since these instruc­
           tions test if the iteration count is negative to ter­
           minate the loop.  If the iteration count is unsigned
           there is a possibility than the 2^{31 + 1} maximum
           passed in registers where possible rather than by
           pushing arguments on to the stack.

       -mparallel-insns
       -mno-parallel-insns
           Allow the generation of parallel instructions.  This
           is enabled by default with -O2.

       -mparallel-mpy
       -mno-parallel-mpy
           Allow the generation of MPY||ADD and MPY||SUB parallel
           instructions, provided -mparallel-insns is also speci­
           fied.  These instructions have tight register con­
           straints which can pessimize the code generation of
           large functions.

       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.

       -mno-ep
       -mep
           Do not optimize (do optimize) basic blocks that use
           the same index pointer 4 or more times to copy pointer
           into the "ep" register, and use the shorter "sld" and
           "sst" instructions.  The -mep option is on by default
           if you optimize.

       -mno-prolog-function
       -mprolog-function
           Do not use (do use) external functions to save and
           restore registers at the prolog and epilog of a func­
           tion.  The external functions are slower, but use less
           code space if more than one function saves the same
           number of registers.  The -mprolog-function option is
           on by default if you optimize.

       -mspace
           Try to make the code as small as possible.  At pre­
           sent, this just turns on the -mep and -mprolog-func­
           tion options.

       -mtda=n
           Put static or global variables whose size is n bytes
           or less into the tiny data area that register "ep"
           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.

       -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 are defined then a
           default target processor will be chosen and the rele­
           vant __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
           This option will suppress generation of the CALLT
           instruction for the v850e flavors of the v850 archi­
           tecture.  The default is -mno-disable-callt which
           allows the CALLT instruction to be used.

       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

       NS32K Options

       These are the -m options defined for the 32000 series.
       The default values for these options depends on which
       style of 32000 was selected when the compiler was config­
       ured; the defaults for the most common choices are given
       below.

       -m32032
       -m32032
           Generate output for a 32032.  This is the default when
           the compiler is configured for 32032 and 32016 based
           systems.

       -m32332
       -m32332
           Generate output for a 32332.  This is the default when
           the compiler is configured for 32332-based systems.

       -m32532
       -m32532
           Generate output for a 32532.  This is the default when
           the compiler is configured for 32532-based systems.

       -m32081
           Generate output containing 32081 instructions for
           floating point.  This is the default for all systems.

       -m32381
           Generate output containing 32381 instructions for
           floating point.  This also implies -m32081.  The 32381
           is only compatible with the 32332 and 32532 cpus.
           This is the default for the pc532-netbsd configura­
           tion.

       -mmulti-add
           Try and generate multiply-add floating point instruc­
           tions "polyF" and "dotF".  This option is only avail­
           able if the -m32381 option is in effect.  Using these
           instructions requires changes to register allocation
           which generally has a negative impact on performance.
           This option should only be enabled when compiling code
           particularly likely to make heavy use of multiply-add
           instructions.

       -mnomulti-add
           Do not try and generate multiply-add floating point
           instructions "polyF" and "dotF".  This is the default
           on all platforms.

       -msoft-float
           machines it is faster to use shifting and masking
           operations.  This is the default for the pc532.

       -mbitfield
           Do use the bit-field instructions.  This is the
           default for all platforms except the pc532.

       -mrtd
           Use a different function-calling convention, in which
           functions that take a fixed number of arguments return
           pop their arguments on return with the "ret" instruc­
           tion.

           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 com­
           piler.

           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.  (Nor­
           mally, extra arguments are harmlessly ignored.)

           This option takes its name from the 680x0 "rtd"
           instruction.

       -mregparam
           Use a different function-calling convention where the
           first two arguments are passed in registers.

           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 com­
           piler.

       -mnoregparam
           Do not pass any arguments in registers.  This is the
           default for all targets.

       -msb
           It is OK to use the sb as an index register which is
           always loaded with zero.  This is the default for the
           pc532-netbsd target.

       -mnosb
           The sb register is not available for use or has not
           been initialized to zero by the run time system.  This
           is the default for all targets except the
           forms.

       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 pro­
           grams (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).

           Instruction set avr3 is for the classic AVR core with
           up to 128K program memory space (MCU types: atmega103,
           atmega603, at43usb320, at76c711).

           Instruction set avr4 is for the enhanced AVR core with
           up to 8K program memory space (MCU types: atmega8,
           atmega83, atmega85).

           Instruction set avr5 is for the enhanced AVR core with
           up to 128K program memory space (MCU types: atmega16,
           atmega161, atmega163, atmega32, atmega323, atmega64,
           atmega128, at43usb355, at94k).

       -msize
           Output instruction sizes to the asm file.

       -minit-stack=N
           Specify the initial stack address, which may be a sym­
           bol or numeric value, __stack is the default.

       -mno-interrupts
           Generated code is not compatible with hardware inter­
           rupts.  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.

       -mdiv
       -mdiv
       -mno-div
           Use the divide instruction.  (Enabled by default).

       -mrelax-immediate
       -mrelax-immediate
       -mno-relax-immediate
           Allow arbitrary sized immediates in bit operations.

       -mwide-bitfields
       -mwide-bitfields
       -mno-wide-bitfields
           Always treat bit-fields as int-sized.

       -m4byte-functions
       -m4byte-functions
       -mno-4byte-functions
           Force all functions to be aligned to a four byte
           boundary.

       -mcallgraph-data
       -mcallgraph-data
       -mno-callgraph-data
           Emit callgraph information.

       -mslow-bytes
       -mslow-bytes
       -mno-slow-bytes
           Prefer word access when reading byte quantities.

       -mlittle-endian
       -mlittle-endian
       -mbig-endian
           Generate code for a little endian target.

       -m210
       -m210
       -m340
           Generate code for the 210 processor.

       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
           ister.  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.

       -mb-step
           Generate code that works around Itanium B step errata.

       -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.

       -mauto-pic
           Generate code that is self-relocatable.  This implies
           -mconstant-gp.  This is useful when compiling firmware
           code.

       -minline-float-divide-min-latency
           Generate code for inline divides of floating point
           values using the minimum latency algorithm.

       -minline-float-divide-max-throughput
           Generate code for inline divides of floating point
           values using the maximum throughput algorithm.

       -minline-int-divide-min-latency
           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.

       -mno-dwarf2-asm
       -mdwarf2-asm
           Don't (or do) generate assembler code for the DWARF2

       -mextmem
           Link the .text, .data, .bss, .strings, .rodata,
           .rodata1, .data1 sections into external memory, which
           starts at location 0x80000000.

       -mextmemory
           Same as the -mextmem switch.

       -monchip
           Link the .text section into onchip text memory, which
           starts at location 0x0.  Also link .data, .bss,
           .strings, .rodata, .rodata1, .data1 sections into
           onchip data memory, which starts at location
           0x20000000.

       -mno-asm-optimize
       -masm-optimize
           Disable (enable) passing -O to the assembler when
           optimizing.  The assembler uses the -O option to auto­
           matically parallelize adjacent short instructions
           where possible.

       -mbranch-cost=n
           Increase the internal costs of branches to n.  Higher
           costs means that the compiler will issue more instruc­
           tions to avoid doing a branch.  The default is 2.

       -mcond-exec=n
           Specify the maximum number of conditionally executed
           instructions that replace a branch.  The default is 4.

       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 instruc­
           tions 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.

       -mbackchain
       -mno-backchain
           Generate (or do not generate) code which maintains an
           explicit backchain within the stack frame that points
           to the caller's frame.  This is currently needed to
           Linux for S/390 ABI.  When -m64 is specified, generate
           code compliant to the Linux for zSeries ABI.  This
           allows GCC in particular to generate 64-bit instruc­
           tions.  For the s390 targets, the default is -m31,
           while the s390x targets default to -m64.

       -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.

       -mdebug
       -mno-debug
           Print (or do not print) additional debug information
           when compiling.  The default is to not print debug
           information.

       CRIS Options

       These options are defined specifically for the CRIS ports.

       -march=architecture-type
       -mcpu=architecture-type
           Generate code for the specified architecture.  The
           choices for architecture-type are v3, v8 and v10 for
           respectively ETRAX 4, ETRAX 100, and ETRAX 100 LX.
           Default is v0 except for cris-axis-linux-gnu, where
           the default is v10.

       -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.

       -melinux-stacksize=n
           Only available with the cris-axis-aout target.
           Arranges for indications in the program to the kernel
           loader that the stack of the program should be set to
           n bytes.

       -metrax4
       -metrax100
           The options -metrax4 and -metrax100 are synonyms for
           -march=v3 and -march=v8 respectively.


       -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 alignment.

       -mno-prologue-epilogue
       -mprologue-epilogue
           With -mno-prologue-epilogue, the normal function pro­
           logue and epilogue that sets up the stack-frame are
           omitted and no return instructions or return sequences
           are generated in the code.  Use this option only
           together with visual inspection of the compiled code:
           no warnings or errors are generated when call-saved
           registers must be saved, or storage for local variable
           needs to be allocated.

       -mno-gotplt
       -mgotplt
           With -fpic and -fPIC, don't generate (do generate)
           instruction sequences that load addresses for func­
           tions from the PLT part of the GOT rather than (tradi­
           tional on other architectures) calls to the PLT.  The
           default is -mgotplt.

       -maout
           Legacy no-op option only recognized with the cris-
           axis-aout target.

       -melf
           Legacy no-op option only recognized with the cris-
           axis-elf and cris-axis-linux-gnu targets.

       -melinux
           Only recognized with the cris-axis-aout target, where
           it selects a GNU/linux-like multilib, include files
           Like -sim, but pass linker options to locate initial­
           ized data at 0x40000000 and zero-initialized data at
           0x80000000.

       MMIX Options

       These options are defined for the MMIX:

       -mlibfuncs
       -mno-libfuncs
           Specify that intrinsic library functions are being
           compiled, passing all values in registers, no matter
           the size.

       -mepsilon
       -mno-epsilon
           Generate floating-point comparison instructions that
           compare with 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 instruc­
           tions 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" assem­
           bly 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
           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.

       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 sup­
           ported.)

       -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 "movstrhi" patterns for copying memory.
           This is the default.

       -mbcopy
           Do not use inline "movstrhi" patterns for copying mem­
           ory.

       -mint16
       -mno-int32
           Use 16-bit "int".  This is the default.

       -mint32
       -mno-int16
           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.

       Xstormy16 Options

       These options are defined for Xstormy16:

       -msim
           Choose startup files and linker script suitable for
           the simulator.

       FRV Options

       -mgpr-32
           Only use the first 32 general purpose registers.

       -mgpr-64
           Use all 64 general purpose registers.

       -mfpr-32
           Use only the first 32 floating point registers.

       -mfpr-64
           Use all 64 floating point registers

       -mhard-float
           Use hardware instructions for floating point opera­
           tions.

           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.

       -mlibrary-pic
           Enable PIC support for building libraries

       -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.

       -mno-cond-move
           Disable the use of conditional-move instructions.

           This switch is mainly for debugging the compiler and
           will likely be removed in a future version.

       -mscc

           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 instruc­
           tions.

           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.

       -mtomcat-stats
       default options.

       -mbig-endian
       -mlittle-endian
           Specify big-endian or little-endian byte ordering for
           the target Xtensa processor.

       -mdensity
       -mno-density
           Enable or disable use of the optional Xtensa code den­
           sity instructions.

       -mmac16
       -mno-mac16
           Enable or disable use of the Xtensa MAC16 option.
           When enabled, GCC will generate MAC16 instructions
           from standard C code, with the limitation that it will
           use neither the MR register file nor any instruction
           that operates on the MR registers.  When this option
           is disabled, GCC will translate 16-bit multiply/accu­
           mulate operations to a combination of core instruc­
           tions and library calls, depending on whether any
           other multiplier options are enabled.

       -mmul16
       -mno-mul16
           Enable or disable use of the 16-bit integer multiplier
           option.  When enabled, the compiler will generate
           16-bit multiply instructions for multiplications of 16
           bits or smaller in standard C code.  When this option
           is disabled, the compiler will either use 32-bit mul­
           tiply or MAC16 instructions if they are available or
           generate library calls to perform the multiply opera­
           tions using shifts and adds.

       -mmul32
       -mno-mul32
           Enable or disable use of the 32-bit integer multiplier
           option.  When enabled, the compiler will generate
           32-bit multiply instructions for multiplications of 32
           bits or smaller in standard C code.  When this option
           is disabled, the compiler will generate library calls
           to perform the multiply operations using either shifts
           and adds or 16-bit multiply instructions if they are
           available.

       -mnsa
       -mno-nsa
           Enable or disable use of the optional normalization
           shift amount ("NSA") instructions to implement the
           built-in "ffs" function.

           cally useful by itself but may be required for other
           options that make use of the boolean registers (e.g.,
           the floating-point option).

       -mhard-float
       -msoft-float
           Enable or disable use of the floating-point option.
           When enabled, GCC generates floating-point instruc­
           tions for 32-bit "float" operations.  When this option
           is disabled, GCC generates library calls to emulate
           32-bit floating-point operations using integer
           instructions.  Regardless of this option, 64-bit "dou­
           ble" operations are always emulated with calls to
           library functions.

       -mfused-madd
       -mno-fused-madd
           Enable or disable use of fused multiply/add and multi­
           ply/subtract instructions in the floating-point
           option.  This has no effect if the floating-point
           option is not also enabled.  Disabling fused multi­
           ply/add and multiply/subtract instructions forces the
           compiler to use separate instructions for the multiply
           and add/subtract operations.  This may be desirable in
           some cases where strict IEEE 754-compliant results are
           required: the fused multiply add/subtract instructions
           do not round the intermediate result, thereby produc­
           ing results with more bits of precision than specified
           by the IEEE standard.  Disabling fused multiply
           add/subtract instructions also ensures that the pro­
           gram 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 liter­
           als and improve code size.  With -mtext-section-liter­
           als, the literals are interspersed in the text section
           in order to keep them as close as possible to their
           aligned instructions like "LOOP", which the assembler
           will always align, either by widening density instruc­
           tions or by inserting no-op instructions.

       -mlongcalls
       -mno-longcalls
           When this option is enabled, GCC instructs the assem­
           bler 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 func­
           tions in other source files.  Specifically, the assem­
           bler translates a direct "CALL" instruction into an
           "L32R" followed by a "CALLX" instruction.  The default
           is -mno-longcalls.  This option should be used in pro­
           grams 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.

       Options for Code Generation Conventions

       These machine-independent options control the interface
       conventions used in code generation.

       Most of them have both positive and negative forms; the
       negative form of -ffoo would be -fno-foo.  In the table
       below, only one of the forms is listed---the one which is
       not the default.  You can figure out the other form by
       either removing no- or adding it.

       -fbounds-check
           For front-ends that support it, generate additional
           code to check that indices used to access arrays are
           within the declared range.  This is currently only
           supported by the Java and Fortran 77 front-ends, where
           this option defaults to true and false respectively.

       -ftrapv
           This option generates traps for signed overflow on
           addition, subtraction, multiplication operations.

       -fexceptions
           Enable exception handling.  Generates extra code
           needed to propagate exceptions.  For some targets,
           this implies GCC will generate frame unwind informa­
           tion for all functions, which can produce significant
           data size overhead, although it does not affect execu­
           where.  Moreover, it only allows trapping instructions
           to throw exceptions, i.e. memory references or float­
           ing 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 gen­
           erate 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
           Return ``short'' "struct" and "union" values in memory
           like longer ones, rather than in registers.  This con­
           vention is less efficient, but it has the advantage of
           allowing intercallability between GCC-compiled files
           and files compiled with other compilers, particularly
           the Portable C Compiler (pcc).

           The precise convention for returning structures in
           memory depends on the target configuration macros.

           Short structures and unions are those whose size and
           alignment match that of some integer type.

           Warning: code compiled with the -fpcc-struct-return
           switch is not binary compatible with code compiled
           with the -freg-struct-return switch.  Use it to con­
           form 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 conven­
           tion is standard for the target.  If there is no stan­
           dard 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.
           erated 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 gen­
           erate 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 gener­
           ate code that is not binary compatible with code gen­
           erated without that switch.  Use it to conform to a
           non-default application binary interface.

       -fshared-data
           Requests that the data and non-"const" variables of
           this compilation be shared data rather than private
           data.  The distinction makes sense only on certain
           operating systems, where shared data is shared between
           processes running the same program, while private data
           exists in one copy per process.

       -fno-common
           In C, allocate even uninitialized global variables in
           the data section of the object file, rather than gen­
           erating them as common blocks.  This has the effect
           that if the same variable is declared (without
           "extern") in two different compilations, you will get
           an error when you link them.  The only reason this
           might be useful is if you wish to verify that the pro­
           gram will work on other systems which always work this
           way.

       -fno-ident
           Ignore the #ident directive.

       -fno-gnu-linker
           Do not output global initializations (such as C++ con­
           structors and destructors) in the form used by the GNU
           linker (on systems where the GNU linker is the stan­
           dard method of handling them).  Use this option when
           you want to use a non-GNU linker, which also requires
           using the collect2 program to make sure the system
           linker includes constructors and destructors.  (col­
           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 debug­
           ging the compiler itself).

           -fno-verbose-asm, the default, causes the extra infor­
           mation to be omitted and is useful when comparing two
           assembler files.

       -fvolatile
           Consider all memory references through pointers to be
           volatile.

       -fvolatile-global
           Consider all memory references to extern and global
           data items to be volatile.  GCC does not consider
           static data items to be volatile because of this
           switch.

       -fvolatile-static
           Consider all memory references to static data to be
           volatile.

       -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 maxi­
           mum 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 16k
           on the m88k, 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.

       -fPIC
           If supported for the target machine, emit position-
           independent code, suitable for dynamic linking and
           avoiding any limit on the size of the global offset
           table.  This option makes a difference on the m68k,
           m88k, and the SPARC.

           Position-independent code requires special support,
           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 allo­
           cated 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 tem­
           poraries or variables that live across a call.  Func­
           tions compiled this way will save and restore the reg­
           ister 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.

           This flag does not have a negative form, because it
           specifies a three-way choice.

       -fpack-struct
           Pack all structure members together without holes.

           Warning: the -fpack-struct switch causes GCC to gener­
           ate code that is not binary compatible with code gen­
           erated without that switch.  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
           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 avail­
           able.  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 pro­
           vided.  (This is normally the case anyways, but if you
           get lucky and the optimizer always expands the func­
           tions inline, you might have gotten away without pro­
           viding static copies.)

           A function may be given the attribute "no_instru­
           ment_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).

       -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 sin­
           gle-threaded environment since stack overflow is auto­
           matically 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 must do that.  The
           switch causes generation of code to ensure that the
           operating system sees the stack being extended.

       -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 tar­
           gets, 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
           alias each other, but may alias global storage.-fargu­
           ment-noalias-global specifies that arguments do not
           alias each other and do not alias global 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-under­
           score, forcibly change the way C symbols are repre­
           sented 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".


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 configu­
       ration 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_UK for English in the United King­
           wise, LC_CTYPE and LC_MESSAGES default to the value of
           the LANG environment variable.  If none of these vari­
           ables are set, GCC defaults to traditional C English
           behavior.

       TMPDIR
           If TMPDIR is set, it specifies the directory to use
           for temporary files.  GCC uses temporary files to hold
           the output of one stage of compilation which is to be
           used as input to the next stage: for example, the out­
           put 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 com­
           bined with the name of a subprogram, but you can spec­
           ify 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 pre­
           fix/lib/gcc-lib/ where 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 nor­
           mally begins with /usr/local/lib/gcc-lib (more pre­
           cisely, 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 nor­
           mally search /usr/local/lib/bar.  These alternate
           directories are searched first; the standard directo­
           ries come next.

       COMPILER_PATH
           The value of COMPILER_PATH is a colon-separated list

       LANG
           This variable is used to pass locale information to
           the compiler.  One way in which this information is
           used is to determine the character set to be used when
           character literals, string literals and comments are
           parsed in C and C++.  When the compiler is configured
           to allow multibyte characters, the following values
           for LANG are recognized:

           C-JIS
               Recognize JIS characters.

           C-SJIS
               Recognize SJIS characters.

           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 sepa­
           rated 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 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
           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 equiva­
           lent to combining the options -MM and -MF, with an
           optional -MT switch too.

       SUNPRO_DEPENDENCIES
           This variable is the same as DEPENDENCIES_OUTPUT (see
           above), except that system header files are not
           ignored, so it implies -M rather than -MM.  However,
           the dependence on the main input file is omitted.


BUGS

       For instructions on reporting bugs, see
       <http://gcc.gnu.org/bugs.html>.  Use of the gccbug script
       to report bugs is recommended.


FOOTNOTES

       1.  On some systems, gcc -shared needs to build supplemen­
           tary stub code for constructors to work.  On multi-
           libbed systems, gcc -shared must select the correct
           support libraries to link against.  Failing to supply
           the correct flags may lead to subtle defects.  Supply­
           ing them in cases where they are not necessary is
           innocuous.


SEE ALSO

       gpl(7), gfdl(7), fsf-funding(7), cpp(1), gcov(1), g77(1),
       as(1), ld(1), gdb(1), adb(1), dbx(1), sdb(1) and the Info
       entries for gcc, cpp, g77, as, ld, binutils and gdb.


AUTHOR

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


COPYRIGHT

       Copyright (c) 1988, 1989, 1992, 1993, 1994, 1995, 1996,
       1997, 1998, 1999, 2000, 2001, 2002, 2003 Free Software
       Foundation, Inc.

       Permission is granted to copy, distribute and/or modify
       this document under the terms of the GNU Free Documenta­
       tion License, Version 1.2 or any later version published
       by the Free Software Foundation; with the Invariant Sec­
       tions 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.

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