@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002 Free Software Foundation, Inc.
+@c 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@ignore
@c man begin COPYRIGHT
Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997,
-1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
+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 Documentation License, Version 1.1 or
@xref{Overall Options,,Options Controlling the Kind of Output}.
@gccoptlist{
-c -S -E -o @var{file} -pipe -pass-exit-codes -x @var{language} @gol
--v -### --target-help --help}
+-v -### --help --target-help --version}
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
-fallow-single-precision -fcond-mismatch @gol
-fsigned-bitfields -fsigned-char @gol
-funsigned-bitfields -funsigned-char @gol
--fwritable-strings -fshort-wchar}
+-fwritable-strings}
@item C++ Language Options
@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@gccoptlist{
--fno-access-control -fcheck-new -fconserve-space @gol
--fno-const-strings -fdollars-in-identifiers @gol
+-fabi-version=@var{n} -fno-access-control -fcheck-new @gol
+-fconserve-space -fno-const-strings -fdollars-in-identifiers @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs -fexternal-templates @gol
-falt-external-templates @gol
-fno-optional-diags -fpermissive @gol
-frepo -fno-rtti -fstats -ftemplate-depth-@var{n} @gol
-fuse-cxa-atexit -fvtable-gc -fno-weak -nostdinc++ @gol
--fno-default-inline -Wctor-dtor-privacy @gol
+-fno-default-inline -Wabi -Wctor-dtor-privacy @gol
-Wnon-virtual-dtor -Wreorder @gol
-Weffc++ -Wno-deprecated @gol
-Wno-non-template-friend -Wold-style-cast @gol
@gccoptlist{
-fconstant-string-class=@var{class-name} @gol
-fgnu-runtime -fnext-runtime -gen-decls @gol
--Wno-protocol -Wselector}
+-Wno-protocol -Wselector -Wundeclared-selector}
@item Language Independent Options
@xref{Language Independent Options,,Options to Control Diagnostic Messages Formatting}.
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{
-fsyntax-only -pedantic -pedantic-errors @gol
--w -W -Wall -Waggregate-return @gol
+-w -W -Wall -Waggregate-return @gol
-Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment @gol
-Wconversion -Wno-deprecated-declarations @gol
-Wdisabled-optimization -Wno-div-by-zero -Werror @gol
-Werror-implicit-function-declaration @gol
-Wimport -Winline -Wno-endif-labels @gol
-Wlarger-than-@var{len} -Wlong-long @gol
--Wmain -Wmissing-braces -Wmissing-declarations @gol
+-Wmain -Wmissing-braces @gol
-Wmissing-format-attribute -Wmissing-noreturn @gol
-Wno-multichar -Wno-format-extra-args -Wno-format-y2k @gol
-Wno-import -Wnonnull -Wpacked -Wpadded @gol
-Wparentheses -Wpointer-arith -Wredundant-decls @gol
-Wreturn-type -Wsequence-point -Wshadow @gol
--Wsign-compare -Wswitch -Wswitch-default -Wswitch-enum @gol
+-Wsign-compare -Wstrict-aliasing @gol
+-Wswitch -Wswitch-default -Wswitch-enum @gol
-Wsystem-headers -Wtrigraphs -Wundef -Wuninitialized @gol
-Wunknown-pragmas -Wunreachable-code @gol
-Wunused -Wunused-function -Wunused-label -Wunused-parameter @gol
@item C-only Warning Options
@gccoptlist{
--Wbad-function-cast -Wmissing-prototypes -Wnested-externs @gol
+-Wbad-function-cast -Wmissing-declarations @gol
+-Wmissing-prototypes -Wnested-externs @gol
-Wstrict-prototypes -Wtraditional}
@item Debugging Options
-fdump-class-hierarchy@r{[}-@var{n}@r{]} @gol
-fdump-tree-original@r{[}-@var{n}@r{]} -fdump-tree-optimized@r{[}-@var{n}@r{]} @gol
-fdump-tree-inlined@r{[}-@var{n}@r{]} @gol
--fmem-report @gol
--fprofile-arcs -ftest-coverage -ftime-report @gol
+-feliminate-dwarf2-dups -fmem-report @gol
+-fprofile-arcs -fsched-verbose=@var{n} @gol
+-ftest-coverage -ftime-report @gol
-g -g@var{level} -gcoff -gdwarf -gdwarf-1 -gdwarf-1+ -gdwarf-2 @gol
-ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ @gol
-p -pg -print-file-name=@var{library} -print-libgcc-file-name @gol
@gccoptlist{
-falign-functions=@var{n} -falign-jumps=@var{n} @gol
-falign-labels=@var{n} -falign-loops=@var{n} @gol
+-fbounds-check @gol
-fbranch-probabilities -fcaller-saves -fcprop-registers @gol
-fcse-follow-jumps -fcse-skip-blocks -fdata-sections @gol
-fdelayed-branch -fdelete-null-pointer-checks @gol
-fif-conversion -fif-conversion2 @gol
-finline-functions -finline-limit=@var{n} -fkeep-inline-functions @gol
-fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
--fmove-all-movables -fnew-ra -fno-default-inline -fno-defer-pop @gol
+-fmove-all-movables -fnew-ra -fno-branch-count-reg @gol
+-fno-default-inline -fno-defer-pop @gol
-fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
--funsafe-math-optimizations -ffinite-math-only -fno-trapping-math @gol
--fno-zero-initialized-in-bss @gol
+-funsafe-math-optimizations -ffinite-math-only @gol
+-fno-trapping-math -fno-zero-initialized-in-bss @gol
-fomit-frame-pointer -foptimize-register-move @gol
-foptimize-sibling-calls -fprefetch-loop-arrays @gol
-freduce-all-givs -fregmove -frename-registers @gol
-freorder-blocks -freorder-functions @gol
-frerun-cse-after-loop -frerun-loop-opt @gol
--fschedule-insns -fschedule-insns2 -fsignaling-nans @gol
+-fschedule-insns -fschedule-insns2 @gol
+-fno-sched-interblock -fno-sched-spec -fsched-spec-load @gol
+-fsched-spec-load-dangerous -fsignaling-nans @gol
-fsingle-precision-constant -fssa -fssa-ccp -fssa-dce @gol
--fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps -ftrapv @gol
--funroll-all-loops -funroll-loops @gol
+-fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps @gol
+-ftrapv -funroll-all-loops -funroll-loops @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
-iprefix @var{file} -iwithprefix @var{dir} @gol
-iwithprefixbefore @var{dir} -isystem @var{dir} @gol
-M -MM -MF -MG -MP -MQ -MT -nostdinc -P -remap @gol
--trigraphs -undef -U@var{macro} -Wp,@var{option}}
+-trigraphs -undef -U@var{macro} -Wp,@var{option} -Xpreprocessor @var{option}}
@item Assembler Option
@xref{Assembler Options,,Passing Options to the Assembler}.
@gccoptlist{
--Wa,@var{option}}
+-Wa,@var{option} -Xassembler @var{option}}
@item Linker Options
@xref{Link Options,,Options for Linking}.
@emph{M68hc1x Options}
@gccoptlist{
-m6811 -m6812 -m68hc11 -m68hc12 @gol
--mauto-incdec -mshort -msoft-reg-count=@var{count}}
+-mauto-incdec -minmax -mlong-calls -mshort @gol
+-msoft-reg-count=@var{count}}
@emph{VAX Options}
@gccoptlist{
-msoft-float -msoft-quad-float -msparclite -mstack-bias @gol
-msupersparc -munaligned-doubles -mv8}
-@emph{Convex Options}
-@gccoptlist{
--mc1 -mc2 -mc32 -mc34 -mc38 @gol
--margcount -mnoargcount @gol
--mlong32 -mlong64 @gol
--mvolatile-cache -mvolatile-nocache}
-
-@emph{AMD29K Options}
-@gccoptlist{
--m29000 -m29050 -mbw -mnbw -mdw -mndw @gol
--mlarge -mnormal -msmall @gol
--mkernel-registers -mno-reuse-arg-regs @gol
--mno-stack-check -mno-storem-bug @gol
--mreuse-arg-regs -msoft-float -mstack-check @gol
--mstorem-bug -muser-registers}
-
@emph{ARM Options}
@gccoptlist{
-mapcs-frame -mno-apcs-frame @gol
-mthumb-interwork -mno-thumb-interwork @gol
-mcpu=@var{name} -march=@var{name} -mfpe=@var{name} @gol
-mstructure-size-boundary=@var{n} @gol
--mbsd -mxopen -mno-symrename @gol
-mabort-on-noreturn @gol
-mlong-calls -mno-long-calls @gol
-msingle-pic-base -mno-single-pic-base @gol
-mno-relocatable -mrelocatable-lib -mno-relocatable-lib @gol
-mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian @gol
-mcall-aix -mcall-sysv -mcall-netbsd @gol
--maix-struct-return -msvr4-struct-return
+-maix-struct-return -msvr4-struct-return @gol
-mabi=altivec -mabi=no-altivec @gol
-mabi=spe -mabi=no-spe @gol
-misel=yes -misel=no @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
-msdata=@var{opt} -mvxworks -mwindiss -G @var{num} -pthread}
+@emph{Darwin Options}
+@gccoptlist{
+-all_load -allowable_client -arch -arch_errors_fatal @gol
+-arch_only -bind_at_load -bundle -bundle_loader @gol
+-client_name -compatibility_version -current_version @gol
+-dependency-file -dylib_file -dylinker_install_name @gol
+-dynamic -dynamiclib -exported_symbols_list @gol
+-filelist -flat_namespace -force_cpusubtype_ALL @gol
+-force_flat_namespace -headerpad_max_install_names @gol
+-image_base -init -install_name -keep_private_externs @gol
+-multi_module -multiply_defined -multiply_defined_unused @gol
+-noall_load -nomultidefs -noprebind -noseglinkedit @gol
+-pagezero_size -prebind -prebind_all_twolevel_modules @gol
+-private_bundle -read_only_relocs -sectalign @gol
+-sectobjectsymbols -whyload -seg1addr @gol
+-sectcreate -sectobjectsymbols -sectorder @gol
+-seg_addr_table -seg_addr_table_filename -seglinkedit @gol
+-segprot -segs_read_only_addr -segs_read_write_addr @gol
+-single_module -static -sub_library -sub_umbrella @gol
+-twolevel_namespace -umbrella -undefined @gol
+-unexported_symbols_list -weak_reference_mismatches -whatsloaded}
+
@emph{RT Options}
@gccoptlist{
-mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs @gol
-m4650 -msingle-float -mmad @gol
-mstats -EL -EB -G @var{num} -nocpp @gol
-mabi=32 -mabi=n32 -mabi=64 -mabi=eabi @gol
--mfix7000 -mno-crt0 -mflush-func=@var{func} -mno-flush-func}
+-mfix7000 -mno-crt0 -mflush-func=@var{func} -mno-flush-func @gol
+-mbranch-likely -mno-branch-likely}
@emph{i386 and x86-64 Options}
@gccoptlist{
-mno-fp-ret-in-387 -msoft-float -msvr3-shlib @gol
-mno-wide-multiply -mrtd -malign-double @gol
-mpreferred-stack-boundary=@var{num} @gol
--mmmx -msse -msse2 -msse-math -m3dnow @gol
+-mmmx -msse -msse2 -m3dnow @gol
-mthreads -mno-align-stringops -minline-all-stringops @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -momit-leaf-frame-pointer @gol
-mno-red-zone@gol
+-mcmodel=@var{code-model} @gol
-m32 -m64}
@emph{HPPA Options}
@gccoptlist{
-march=@var{architecture-type} @gol
-mbig-switch -mdisable-fpregs -mdisable-indexing @gol
--mfast-indirect-calls -mgas -mjump-in-delay @gol
+-mfast-indirect-calls -mgas -mgnu-ld -mhp-ld @gol
+-mjump-in-delay -mlinker-opt -mlong-calls @gol
-mlong-load-store -mno-big-switch -mno-disable-fpregs @gol
-mno-disable-indexing -mno-fast-indirect-calls -mno-gas @gol
-mno-jump-in-delay -mno-long-load-store @gol
-mno-portable-runtime -mno-soft-float @gol
-mno-space-regs -msoft-float -mpa-risc-1-0 @gol
-mpa-risc-1-1 -mpa-risc-2-0 -mportable-runtime @gol
--mschedule=@var{cpu-type} -mspace-regs}
+-mschedule=@var{cpu-type} -mspace-regs -msio -mwsio}
@emph{Intel 960 Options}
@gccoptlist{
-mcpu=@var{cpu-type} -mtune=@var{cpu-type} @gol
-mbwx -mmax -mfix -mcix @gol
-mfloat-vax -mfloat-ieee @gol
--mexplicit-relocs -msmall-data -mlarge-data @gol
+-mexplicit-relocs -msmall-data -mlarge-data -msmall-text -mlarge-text @gol
-mmemory-latency=@var{time}}
@emph{DEC Alpha/VMS Options}
@gccoptlist{
-mvms-return-codes}
-@emph{Clipper Options}
-@gccoptlist{
--mc300 -mc400}
-
@emph{H8/300 Options}
@gccoptlist{
--mrelax -mh -ms -mint32 -malign-300}
+-mrelax -mh -ms -mn -mint32 -malign-300}
@emph{SH Options}
@gccoptlist{
-mlong-calls -mno-long-calls -mep -mno-ep @gol
-mprolog-function -mno-prolog-function -mspace @gol
-mtda=@var{n} -msda=@var{n} -mzda=@var{n} @gol
+-mapp-regs -mno-app-regs @gol
+-mdisable-callt -mno-disable-callt @gol
+-mv850e @gol
-mv850 -mbig-switch}
@emph{NS32K Options}
@gccoptlist{
-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
-mvolatile-asm-stop -mb-step -mregister-names -mno-sdata @gol
--mconstant-gp -mauto-pic -minline-divide-min-latency @gol
--minline-divide-max-throughput -mno-dwarf2-asm @gol
+-mconstant-gp -mauto-pic -minline-float-divide-min-latency @gol
+-minline-float-divide-max-throughput -minline-int-divide-min-latency @gol
+-minline-int-divide-max-throughput -mno-dwarf2-asm @gol
-mfixed-range=@var{register-range}}
@emph{D30V Options}
@gccoptlist{
--mextmem -mextmemory -monchip -mno-asm-optimize -masm-optimize @gol
--mbranch-cost=@var{n} -mcond-exec=@var{n}}
+-mextmem -mextmemory -monchip -mno-asm-optimize @gol
+-masm-optimize -mbranch-cost=@var{n} -mcond-exec=@var{n}}
@emph{S/390 and zSeries Options}
@gccoptlist{
+-mcpu=@var{cpu-type} -march=@var{cpu-type} @gol
-mhard-float -msoft-float -mbackchain -mno-backchain @gol
-msmall-exec -mno-small-exec -mmvcle -mno-mvcle @gol
--m64 -m31 -mdebug -mno-debug}
+-m64 -m31 -mdebug -mno-debug -mesa -mzarch}
@emph{CRIS Options}
@gccoptlist{
-mtarget-align -mno-target-align @gol
-mlongcalls -mno-longcalls}
+@emph{FRV Options}
+@gccoptlist{
+-mgpr-32 -mgpr-64 -mfpr-32 -mfpr-64 -mhard-float -msoft-float @gol
+-malloc-cc -mfixed-cc -mdword -mno-dword -mdouble -mno-double @gol
+-mmedia -mno-media -mmuladd -mno-muladd -mlibrary-pic -macc-4 @gol
+-macc-8 -mpack -mno-pack -mno-eflags -mcond-move -mno-cond-move @gol
+-mscc -mno-scc -mcond-exec -mno-cond-exec -mvliw-branch -mno-vliw-branch @gol
+-mmulti-cond-exec -mno-multi-cond-exec -mnested-cond-exec @gol
+-mno-nested-cond-exec -mtomcat-stats @gol
+-mcpu=@var{cpu}}
+
+
+
@item Code Generation Options
@xref{Code Gen Options,,Options for Code Generation Conventions}.
@gccoptlist{
-fno-common -fno-ident -fno-gnu-linker @gol
-fpcc-struct-return -fpic -fPIC @gol
-freg-struct-return -fshared-data -fshort-enums @gol
--fshort-double -fvolatile @gol
+-fshort-double -fshort-wchar -fvolatile @gol
-fvolatile-global -fvolatile-static @gol
-fverbose-asm -fpack-struct -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
-fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fleading-underscore -ftls-model=@var{model}}
+-fargument-noalias-global -fleading-underscore @gol
+-ftls-model=@var{model}}
@end table
@menu
@itemx @var{file}.cp
@itemx @var{file}.cxx
@itemx @var{file}.cpp
+@itemx @var{file}.CPP
@itemx @var{file}.c++
@itemx @var{file}.C
C++ source code which must be preprocessed. Note that in @samp{.cxx},
@opindex target-help
Print (on the standard output) a description of target specific command
line options for each tool.
+
+@item --version
+@opindex version
+Display the version number and copyrights of the invoked GCC.
@end table
@node Invoking G++
@cindex suffixes for C++ source
@cindex C++ source file suffixes
C++ source files conventionally use one of the suffixes @samp{.C},
-@samp{.cc}, @samp{.cpp}, @samp{.c++}, @samp{.cp}, or @samp{.cxx};
+@samp{.cc}, @samp{.cpp}, @samp{.CPP}, @samp{.c++}, @samp{.cp}, or @samp{.cxx};
preprocessed C++ files use the suffix @samp{.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
@item -std=
@opindex std
Determine the language standard. This option is currently only
-supported when compiling C@. A value for this option must be provided;
-possible values are
+supported when compiling C or C++. A value for this option must be
+provided; possible values are
@table @samp
@item c89
ISO C99 plus GNU extensions. When ISO C99 is fully implemented in GCC,
this will become the default. The name @samp{gnu9x} is deprecated.
+@item c++98
+The 1998 ISO C++ standard plus amendments.
+
+@item gnu++98
+The same as @option{-std=c++98} plus GNU extensions. This is the
+default for C++ code.
@end table
Even when this option is not specified, you can still use some of the
Writing into string constants is a very bad idea; ``constants'' should
be constant.
-
-@item -fshort-wchar
-@opindex fshort-wchar
-Override the underlying type for @samp{wchar_t} to be @samp{short
-unsigned int} instead of the default for the target. This option is
-useful for building programs to run under WINE@.
@end table
@node C++ Dialect Options
Here is a list of options that are @emph{only} for compiling C++ programs:
@table @gcctabopt
+
+@item -fabi-version=@var{n}
+@opindex fabi-version
+Use version @var{n} of the C++ ABI. Version 1 is the version of the C++
+ABI that first appeared in G++ 3.2. Version 0 will always be the
+version that conforms most closely to the C++ ABI specification.
+Therefore, the ABI obtained using version 0 will change as ABI bugs are
+fixed.
+
+The default is version 1.
+
@item -fno-access-control
@opindex fno-access-control
Turn off all access checking. This switch is mainly useful for working
functions will have linkage like inline functions; they just won't be
inlined by default.
+@item -Wabi @r{(C++ only)}
+@opindex Wabi
+Warn when G++ generates code that is probably not compatible with the
+vendor-neutral C++ ABI. Although an effort has been made to warn about
+all such cases, there are probably some cases that are not warned about,
+even though G++ is generating incompatible code. There may also be
+cases where warnings are emitted even though the code that is generated
+will be compatible.
+
+You should rewrite your code to avoid these warnings if you are
+concerned about the fact that code generated by G++ may not be binary
+compatible with code generated by other compilers.
+
+The known incompatibilities at this point include:
+
+@itemize @bullet
+
+@item
+Incorrect handling of tail-padding for bit-fields. G++ may attempt to
+pack data into the same byte as a base class. For example:
+
+@smallexample
+struct A @{ virtual void f(); int f1 : 1; @};
+struct B : public A @{ int f2 : 1; @};
+@end smallexample
+
+@noindent
+In this case, G++ will place @code{B::f2} into the same byte
+as@code{A::f1}; other compilers will not. You can avoid this problem
+by explicitly padding @code{A} so that its size is a multiple of the
+byte size on your platform; that will cause G++ and other compilers to
+layout @code{B} identically.
+
+@item
+Incorrect handling of tail-padding for virtual bases. G++ does not use
+tail padding when laying out virtual bases. For example:
+
+@smallexample
+struct A @{ virtual void f(); char c1; @};
+struct B @{ B(); char c2; @};
+struct C : public A, public virtual B @{@};
+@end smallexample
+
+@noindent
+In this case, G++ will not place @code{B} into the tail-padding for
+@code{A}; other compilers will. You can avoid this problem by
+explicitly padding @code{A} so that its size is a multiple of its
+alignment (ignoring virtual base classes); that will cause G++ and other
+compilers to layout @code{C} identically.
+
+@item
+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:
+
+@smallexample
+union U @{ int i : 4096; @};
+@end smallexample
+
+@noindent
+Assuming that an @code{int} does not have 4096 bits, G++ will make the
+union too small by the number of bits in an @code{int}.
+
+@item
+Empty classes can be placed at incorrect offsets. For example:
+
+@smallexample
+struct A @{@};
+
+struct B @{
+ A a;
+ virtual void f ();
+@};
+
+struct C : public B, public A @{@};
+@end smallexample
+
+@noindent
+G++ will place the @code{A} base class of @code{C} at a nonzero offset;
+it should be placed at offset zero. G++ mistakenly believes that the
+@code{A} data member of @code{B} is already at offset zero.
+
+@item
+Names of template functions whose types involve @code{typename} or
+template template parameters can be mangled incorrectly.
+
+@smallexample
+template <typename Q>
+void f(typename Q::X) @{@}
+
+template <template <typename> class Q>
+void f(typename Q<int>::X) @{@}
+@end smallexample
+
+@noindent
+Instantiations of these templates may be mangled incorrectly.
+
+@end itemize
+
@item -Wctor-dtor-privacy @r{(C++ only)}
@opindex Wctor-dtor-privacy
Warn when a class seems unusable, because all the constructors or
destructors in a class are private and the class has no friends or
-public static member functions.
+public static member functions. This warning is enabled by default.
@item -Wnon-virtual-dtor @r{(C++ only)}
@opindex Wnon-virtual-dtor
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 @option{-Wall}.
@item -Wreorder @r{(C++ only)}
@opindex Wreorder
Here the compiler will warn that the member initializers for @samp{i}
and @samp{j} will be rearranged to match the declaration order of the
-members.
+members. This warning is enabled by @option{-Wall}.
@end table
The following @option{-W@dots{}} options are not affected by @option{-Wall}.
@item -fnext-runtime
@opindex fnext-runtime
Generate output compatible with the NeXT runtime. This is the default
-for NeXT-based systems, including Darwin and Mac OS X@.
+for NeXT-based systems, including Darwin and Mac OS X@. The macro
+@code{__NEXT_RUNTIME__} is predefined if (and only if) this option is
+used.
@item -gen-decls
@opindex gen-decls
@item -Wno-protocol
@opindex Wno-protocol
-Do not warn if methods required by a protocol are not implemented
-in the class adopting it.
+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 @code{-Wno-protocol} option, then
+methods inherited from the superclass are considered to be implemented,
+and no warning is issued for them.
@item -Wselector
@opindex Wselector
-Warn if a selector has multiple methods of different types defined.
+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 @code{@@selector(@dots{})}
+expression, a corresponding method with that selector has been found
+during compilation. Because these checks scan the method table only at
+the end of compilation, these warnings are not produced if the final
+stage of compilation is not reached, for example because an error is
+found during compilation, or because the @code{-fsyntax-only} option is
+being used.
+
+@item -Wundeclared-selector
+@opindex Wundeclared-selector
+Warn if a @code{@@selector(@dots{})} expression referring to an
+undeclared selector is found. A selector is considered undeclared if no
+method with that name has been declared (explicitly, in an
+@code{@@interface} or @code{@@protocol} declaration, or implicitly, in
+an @code{@@implementation} section) before the
+@code{@@selector(@dots{})} expression. This option always performs its
+checks as soon as a @code{@@selector(@dots{})} expression is found
+(while @code{-Wselector} 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.
@c not documented because only avail via -Wp
@c @item -print-objc-runtime-info
@item -Wunused
@opindex Wunused
-All all the above @option{-Wunused} options combined.
+All the above @option{-Wunused} options combined.
In order to get a warning about an unused function parameter, you must
either specify @samp{-W -Wunused} or separately specify
you use that never return as @code{noreturn}. @xref{Function
Attributes}.
-@item -Wreorder @r{(C++ only)}
-@opindex Wreorder
-@cindex reordering, warning
-@cindex warning for reordering of member initializers
-Warn when the order of member initializers given in the code does not
-match the order in which they must be executed. For instance:
-
@item -Wunknown-pragmas
@opindex Wunknown-pragmas
@cindex warning for unknown pragmas
for unknown pragmas in system header files. This is not the case if
the warnings were only enabled by the @option{-Wall} command line option.
+@item -Wstrict-aliasing
+@opindex Wstrict-aliasing
+This option is only active when @option{-fstrict-aliasing} is 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 @option{-Wall}.
+
@item -Wall
@opindex Wall
All of the above @samp{-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.
+conjunction with macros. This also enables some language-specific
+warnings described in @ref{C++ Dialect Options} and
+@ref{Objective-C Dialect Options}.
@end table
The following @option{-W@dots{}} options are not implied by @option{-Wall}.
The idea behind this is that sometimes it is convenient (for the
programmer) to consider floating-point values as approximations to
infinitely precise real numbers. If you are doing this, then you need
-to compute (by analysing the code, or in some other way) the maximum or
+to compute (by analyzing the code, or in some other way) the maximum or
likely maximum error that the computation introduces, and allow for it
when performing comparisons (and when producing output, but that's a
different problem). In particular, instead of testing for equality, you
a concatenated debug level. Instead use an additional @option{-g@var{level}}
option to change the debug level for DWARF1 or DWARF2.
+@item -feliminate-dwarf2-dups
+@opindex 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 @option{-gdwarf-2}.
+
@cindex @code{prof}
@item -p
@opindex p
the source files you want data about, and you must also use it when
linking.
-@cindex @code{tcov}
-@item -a
-@opindex a
-Generate extra code to write profile information for basic blocks, which will
-record the number of times each basic block is executed, the basic block start
-address, and the function name containing the basic block. If @option{-g} is
-used, the line number and filename of the start of the basic block will also be
-recorded. If not overridden by the machine description, the default action is
-to append to the text file @file{bb.out}.
-
-This data could be analyzed by a program like @code{tcov}. Note,
-however, that the format of the data is not what @code{tcov} expects.
-Eventually GNU @code{gprof} should be extended to process this data.
-
@item -Q
@opindex Q
Makes the compiler print out each function name as it is compiled, and
@item -fprofile-arcs
@opindex fprofile-arcs
-Instrument @dfn{arcs} during compilation to generate coverage data
-or for profile-directed block ordering. During execution the program
+Instrument @dfn{arcs} during compilation to generate coverage data or
+for profile-directed block ordering. During execution the program
records how many times each branch is executed and how many times it is
taken. When the compiled program exits it saves this data to a file
-called @file{@var{sourcename}.da} for each source file.
+called @file{@var{auxname}.da} for each source file. @var{auxname} is
+generated from the name of the output file, if explicitly specified and
+it is not the final executable, otherwise it is the basename of the
+source file. In both cases any suffix is removed (e.g. @file{foo.da}
+for input file @file{dir/foo.c}, or @file{dir/foo.da} for output file
+specified as @option{-o dir/foo.o}).
For profile-directed block ordering, compile the program with
@option{-fprofile-arcs} plus optimization and code generation options,
Control Optimization}).
The other use of @option{-fprofile-arcs} is for use with @code{gcov},
-when it is used with the @option{-ftest-coverage} option. GCC
-supports two methods of determining code coverage: the options that
-support @code{gcov}, and options @option{-a} and @option{-ax}, which
-write information to text files. The options that support @code{gcov}
-do not need to instrument every arc in the program, so a program compiled
-with them runs faster than a program compiled with @option{-a}, which
-adds instrumentation code to every basic block in the program. The
-tradeoff: since @code{gcov} does not have execution counts for all
-branches, it must start with the execution counts for the instrumented
-branches, and then iterate over the program flow graph until the entire
-graph has been solved. Hence, @code{gcov} runs a little more slowly than
-a program which uses information from @option{-a} and @option{-ax}.
+when it is used with the @option{-ftest-coverage} option.
With @option{-fprofile-arcs}, for each function of your program GCC
creates a program flow graph, then finds a spanning tree for the graph.
instrumentation code can be added to the block; otherwise, a new basic
block must be created to hold the instrumentation code.
-This option makes it possible to estimate branch probabilities and to
-calculate basic block execution counts. In general, basic block
-execution counts as provided by @option{-a} do not give enough
-information to estimate all branch probabilities.
-
@need 2000
@item -ftest-coverage
@opindex ftest-coverage
Create data files for the @code{gcov} code-coverage utility
-(@pxref{Gcov,, @code{gcov}: a GCC Test Coverage Program}).
-The data file names begin with the name of your source file:
+(@pxref{Gcov,, @code{gcov}: a GCC Test Coverage Program}). See
+@option{-fprofile-arcs} option above for a description of @var{auxname}.
@table @gcctabopt
-@item @var{sourcename}.bb
+@item @var{auxname}.bb
A mapping from basic blocks to line numbers, which @code{gcov} uses to
associate basic block execution counts with line numbers.
-@item @var{sourcename}.bbg
+@item @var{auxname}.bbg
A list of all arcs in the program flow graph. This allows @code{gcov}
to reconstruct the program flow graph, so that it can compute all basic
block and arc execution counts from the information in the
-@code{@var{sourcename}.da} file.
+@file{@var{auxname}.da} file.
@end table
Use @option{-ftest-coverage} with @option{-fprofile-arcs}; the latter
execution counts to another data file:
@table @gcctabopt
-@item @var{sourcename}.da
+@item @var{auxname}.da
Runtime arc execution counts, used in conjunction with the arc
-information in the file @code{@var{sourcename}.bbg}.
+information in the file @file{@var{auxname}.bbg}.
@end table
Coverage data will map better to the source files if
Says to make debugging dumps during compilation at times specified by
@var{letters}. This is used for debugging the compiler. The file names
for most of the dumps are made by appending a pass number and a word to
-the source file name (e.g. @file{foo.c.00.rtl} or @file{foo.c.01.sibling}).
-Here are the possible letters for use in @var{letters}, and their meanings:
+the @var{dumpname}. @var{dumpname} is generated from the name of the
+output file, if explicitly specified and it is not an executable,
+otherwise it is the basename of the source file. In both cases any
+suffix is removed (e.g. @file{foo.00.rtl} or @file{foo.01.sibling}).
+Here are the possible letters for use in @var{letters}, and their
+meanings:
@table @samp
@item A
Annotate the assembler output with miscellaneous debugging information.
@item b
@opindex db
-Dump after computing branch probabilities, to @file{@var{file}.15.bp}.
+Dump after computing branch probabilities, to @file{@var{file}.14.bp}.
@item B
@opindex dB
-Dump after block reordering, to @file{@var{file}.30.bbro}.
+Dump after block reordering, to @file{@var{file}.32.bbro}.
@item c
@opindex dc
-Dump after instruction combination, to the file @file{@var{file}.17.combine}.
+Dump after instruction combination, to the file @file{@var{file}.19.combine}.
@item C
@opindex dC
-Dump after the first if conversion, to the file @file{@var{file}.18.ce}.
+Dump after the first if conversion, to the file @file{@var{file}.15.ce1}.
@item d
@opindex dd
-Dump after delayed branch scheduling, to @file{@var{file}.32.dbr}.
+Dump after delayed branch scheduling, to @file{@var{file}.34.dbr}.
@item D
@opindex dD
Dump all macro definitions, at the end of preprocessing, in addition to
@file{@var{file}.07.ussa}.
@item E
@opindex dE
-Dump after the second if conversion, to @file{@var{file}.27.ce2}.
+Dump after the second if conversion, to @file{@var{file}.29.ce3}.
@item f
@opindex df
-Dump after life analysis, to @file{@var{file}.16.life}.
+Dump after life analysis, to @file{@var{file}.18.life}.
@item F
@opindex dF
Dump after purging @code{ADDRESSOF} codes, to @file{@var{file}.10.addressof}.
@item g
@opindex dg
-Dump after global register allocation, to @file{@var{file}.22.greg}.
+Dump after global register allocation, to @file{@var{file}.24.greg}.
@item h
@opindex dh
Dump after finalization of EH handling code, to @file{@var{file}.02.eh}.
@item k
@opindex dk
-Dump after reg-to-stack conversion, to @file{@var{file}.29.stack}.
+Dump after reg-to-stack conversion, to @file{@var{file}.31.stack}.
@item o
@opindex do
-Dump after post-reload optimizations, to @file{@var{file}.23.postreload}.
+Dump after post-reload optimizations, to @file{@var{file}.25.postreload}.
@item G
@opindex dG
Dump after GCSE, to @file{@var{file}.11.gcse}.
Dump after the first jump optimization, to @file{@var{file}.03.jump}.
@item k
@opindex dk
-Dump after conversion from registers to stack, to @file{@var{file}.33.stack}.
+Dump after conversion from registers to stack, to @file{@var{file}.31.stack}.
@item l
@opindex dl
-Dump after local register allocation, to @file{@var{file}.21.lreg}.
+Dump after local register allocation, to @file{@var{file}.23.lreg}.
@item L
@opindex dL
Dump after loop optimization, to @file{@var{file}.12.loop}.
@item M
@opindex dM
-Dump after performing the machine dependent reorganisation pass, to
-@file{@var{file}.31.mach}.
+Dump after performing the machine dependent reorganization pass, to
+@file{@var{file}.33.mach}.
@item n
@opindex dn
-Dump after register renumbering, to @file{@var{file}.26.rnreg}.
+Dump after register renumbering, to @file{@var{file}.28.rnreg}.
@item N
@opindex dN
-Dump after the register move pass, to @file{@var{file}.19.regmove}.
+Dump after the register move pass, to @file{@var{file}.21.regmove}.
@item r
@opindex dr
Dump after RTL generation, to @file{@var{file}.00.rtl}.
@item R
@opindex dR
-Dump after the second scheduling pass, to @file{@var{file}.28.sched2}.
+Dump after the second scheduling pass, to @file{@var{file}.30.sched2}.
@item s
@opindex ds
Dump after CSE (including the jump optimization that sometimes follows
CSE), to @file{@var{file}.09.cse}.
@item S
@opindex dS
-Dump after the first scheduling pass, to @file{@var{file}.20.sched}.
+Dump after the first scheduling pass, to @file{@var{file}.22.sched}.
@item t
@opindex dt
Dump after the second CSE pass (including the jump optimization that
-sometimes follows CSE), to @file{@var{file}.13.cse2}.
+sometimes follows CSE), to @file{@var{file}.17.cse2}.
@item u
@opindex du
-Dump after null pointer ellimination pass ti @file{@var{file}.08.null}.
+Dump after null pointer elimination pass to @file{@var{file}.08.null}.
@item w
@opindex dw
-Dump after the second flow pass, to @file{@var{file}.24.flow2}.
+Dump after the second flow pass, to @file{@var{file}.26.flow2}.
@item X
@opindex dX
Dump after SSA dead code elimination, to @file{@var{file}.06.ssadce}.
@item z
@opindex dz
-Dump after the peephole pass, to @file{@var{file}.25.peephole2}.
+Dump after the peephole pass, to @file{@var{file}.27.peephole2}.
@item a
@opindex da
Produce all the dumps listed above.
Dump after function inlining, to @file{@var{file}.inlined}.
@end table
+@item -fsched-verbose=@var{n}
+@opindex fsched-verbose
+On targets that use instruction scheduling, this option controls the
+amount of debugging output the scheduler prints. This information is
+written to standard error, unless @option{-dS} or @option{-dR} is
+specified, in which case it is output to the usual dump
+listing file, @file{.sched} or @file{.sched2} respectively. However
+for @var{n} greater than nine, the output is always printed to standard
+error.
+
+For @var{n} greater than zero, @option{-fsched-verbose} outputs the
+same information as @option{-dRS}. For @var{n} greater than one, it
+also output basic block probabilities, detailed ready list information
+and unit/insn info. For @var{n} greater than two, it includes RTL
+at abort point, control-flow and regions info. And for @var{n} over
+four, @option{-fsched-verbose} also includes dependence info.
+
@item -save-temps
@opindex save-temps
Store the usual ``temporary'' intermediate files permanently; place them
@cindex optimize options
@cindex options, optimization
-These options control various sorts of optimizations:
+These options control various sorts of optimizations.
+
+Without any optimization option, the compiler's goal is to reduce the
+cost of compilation and to make debugging produce the expected
+results. Statements are independent: if you stop the program with a
+breakpoint between statements, you can then assign a new value to any
+variable or change the program counter to any other statement in the
+function and get exactly the results you would expect from the source
+code.
+
+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.
@table @gcctabopt
@item -O
Optimize. Optimizing compilation takes somewhat more time, and a lot
more memory for a large function.
-Without @option{-O}, the compiler's goal is to reduce the cost of
-compilation and to make debugging produce the expected results.
-Statements are independent: if you stop the program with a breakpoint
-between statements, you can then assign a new value to any variable or
-change the program counter to any other statement in the function and
-get exactly the results you would expect from the source code.
-
With @option{-O}, the compiler tries to reduce code size and execution
time, without performing any optimizations that take a great deal of
compilation time.
+@option{-O} turns on the following optimization flags:
+@gccoptlist{-fdefer-pop
+-fmerge-constants
+-fthread-jumps
+-floop-optimize
+-fcrossjumping
+-fif-conversion
+-fif-conversion2
+-fdelayed-branch
+-fguess-branch-probability
+-fcprop-registers}
+
+@option{-O} also turns on @option{-fomit-frame-pointer} on machines
+where doing so does not interfere with debugging.
+
@item -O2
@opindex O2
Optimize even more. GCC performs nearly all supported optimizations
As compared to @option{-O}, this option increases both compilation time
and the performance of the generated code.
-@option{-O2} turns on all optional optimizations except for loop
-unrolling, function inlining, and register renaming. It also turns on
-the @option{-fforce-mem} and @option{-fstrict-aliasing} option on all
-machines and frame pointer elimination on machines where doing so does
-not interfere with debugging.
+@option{-O2} turns on all optimization flags specified by @option{-O}. It
+also turns on the following optimization flags:
+@gccoptlist{-fforce-mem
+-foptimize-sibling-calls
+-fstrength-reduce
+-fcse-follow-jumps -fcse-skip-blocks
+-frerun-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 -freorder-functions
+-fstrict-aliasing
+-falign-functions -falign-jumps
+-falign-loops -falign-labels}
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
@item -O0
@opindex O0
-Do not optimize.
+Do not optimize. This is the default.
@item -Os
@opindex Os
do not typically increase code size. It also performs further
optimizations designed to reduce code size.
+@option{-Os} disables the following optimization flags:
+@gccoptlist{-falign-functions -falign-jumps -falign-loops
+-falign-labels -freorder-blocks -fprefetch-loop-arrays}
+
If you use multiple @option{-O} options, with or without level numbers,
the last such option is the one that is effective.
@end table
Options of the form @option{-f@var{flag}} specify machine-independent
flags. Most flags have both positive and negative forms; the negative
-form of @option{-ffoo} would be @option{-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 @samp{no-} or
-adding it.
+form of @option{-ffoo} would be @option{-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 @samp{no-}
+or adding it.
+
+The following options control specific optimizations. They are either
+activated by @option{-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.
@table @gcctabopt
@item -ffloat-store
@opindex finline-limit
By default, gcc limits the size of functions that can be inlined. This flag
allows the control of this limit for functions that are explicitly marked as
-inline (ie marked with the inline keyword or defined within the class
+inline (i.e., marked with the inline keyword or defined within the class
definition in c++). @var{n} is the size of functions that can be inlined in
number of pseudo instructions (not counting parameter handling). The default
value of @var{n} is 600.
@item -fmerge-constants
Attempt to merge identical constants (string constants and floating point
-constants) accross compilation units.
+constants) across compilation units.
-This option is default for optimized compilation if assembler and linker
-support it. Use @option{-fno-merge-constants} to inhibit this behavior.
+This option is the default for optimized compilation if the assembler and
+linker support it. Use @option{-fno-merge-constants} to inhibit this
+behavior.
@item -fmerge-all-constants
Attempt to merge identical constants and identical variables.
for testing, so we are interested to hear about miscompilations with
@option{-fnew-ra}.
+@item -fno-branch-count-reg
+@opindex fno-branch-count-reg
+Do not use ``decrement and branch'' instructions on a count register,
+but instead generate a sequence of instructions that decrement a
+register, compare it against zero, then branch based upon the result.
+This option is only meaningful on architectures that support such
+instructions, which include x86, PowerPC, IA-64 and S/390.
+
@item -fno-function-cse
@opindex fno-function-cse
Do not put function addresses in registers; make each instruction that
assumptions based on that.
The default is @option{-fzero-initialized-in-bss}.
-@end table
-
-The following options control specific optimizations. The @option{-O2}
-option turns on all of these optimizations except @option{-funroll-loops}
-and @option{-funroll-all-loops}. On most machines, the @option{-O} option
-turns on the @option{-fthread-jumps} and @option{-fdelayed-branch} options,
-but specific machines may handle it differently.
-You can use the following flags in the rare cases when ``fine-tuning''
-of optimizations to be performed is desired.
+@item -fbounds-check
+@opindex 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.
-Not all of the optimizations performed by GCC have @option{-f} options
-to control them.
-
-@table @gcctabopt
@item -fstrength-reduce
@opindex fstrength-reduce
Perform the optimizations of loop strength reduction and
@emph{Note:} When compiling a program using computed gotos, a GCC
extension, you may get better runtime performance if you disable
-the global common subexpression elmination pass by adding
+the global common subexpression elimination pass by adding
@option{-fno-gcse} to the command line.
@item -fgcse-lm
especially useful on machines with a relatively small number of
registers and where memory load instructions take more than one cycle.
+@item -fno-sched-interblock
+@opindex fno-sched-interblock
+Don't schedule instructions across basic blocks. This is normally
+enabled by default when scheduling before register allocation, i.e.@:
+with @option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fno-sched-spec
+@opindex fno-sched-spec
+Don't allow speculative motion of non-load instructions. This is normally
+enabled by default when scheduling before register allocation, i.e.@:
+with @option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fsched-spec-load
+@opindex fsched-spec-load
+Allow speculative motion of some load instructions. This only makes
+sense when scheduling before register allocation, i.e.@: with
+@option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fsched-spec-load-dangerous
+@opindex fsched-spec-load-dangerous
+Allow speculative motion of more load instructions. This only makes
+sense when scheduling before register allocation, i.e.@: with
+@option{-fschedule-insns} or at @option{-O2} or higher.
+
@item -ffunction-sections
@itemx -fdata-sections
@opindex ffunction-sections
Use these options on systems where the linker can perform optimizations
to improve locality of reference in the instruction space. HPPA
-processors running HP-UX and Sparc processors running Solaris 2 have
+processors running HP-UX and SPARC processors running Solaris 2 have
linkers with such optimizations. Other systems using the ELF object format
as well as AIX may have these optimizations in the future.
subsections @code{text.hot} for most frequently executed functions and
@code{text.unlikely} for unlikely executed functions. Reordering is done by
the linker so object file format must support named sections and linker must
-place them in resonable way.
+place them in a reasonable way.
Also profile feedback must be available in to make this option effective. See
@option{-fprofile-arcs} for details.
@item tracer-dynamic-coverage
@itemx tracer-dynamic-coverage-feedback
-This value is used to limit superblock formation once given percentage of
-executed instructions is covered. This limits unnecesary code size expansion.
+This value is used to limit superblock formation once the given percentage of
+executed instructions is covered. This limits unnecessary code size
+expansion.
The @option{tracer-dynamic-coverage-feedback} is used only when profile
feedback is available. The real profiles (as opposed to statically estimated
@item 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 elliminated later in
+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.
Stop forward growth if the best edge do have probability lower than this
threshold.
-Similary to @option{tracer-dynamic-coverage} two values are present, one for
+Similarly to @option{tracer-dynamic-coverage} two values are present, one for
compilation for profile feedback and one for compilation without. The value
for compilation with profile feedback needs to be more conservative (higher) in
order to make tracer effective.
+@item ggc-min-expand
+
+GCC uses a garbage collector to manage its own memory allocation. This
+parameter specifies the minimum percentage by which the garbage
+collector's heap should be allowed to expand between collections.
+Tuning this may improve compilation speed; it has no effect on code
+generation.
+
+The default is 30%. Setting this parameter and
+@option{ggc-min-heapsize} to zero causes a full collection to occur at
+every opportunity. This is extremely slow, but can be useful for
+debugging.
+
+@item 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 @option{ggc-min-expand}% beyond @option{ggc-min-heapsize}. Again,
+tuning this may improve compilation speed, and has no effect on code
+generation.
+
+The default is 4096 (four megabytes). Setting this parameter very large
+effectively disables garbage collection. Setting this parameter and
+@option{ggc-min-expand} to zero causes a full collection to occur at
+every opportunity.
+
@end table
@end table
they cause the preprocessor output to be unsuitable for actual
compilation.
+@table @gcctabopt
@opindex Wp
You can use @option{-Wp,@var{option}} to bypass the compiler driver
and pass @var{option} directly through to the preprocessor. If
you should avoid using @option{-Wp} and let the driver handle the
options instead.
+@item -Xpreprocessor @var{option}
+@opindex preprocessor
+Pass @var{option} as an option to the preprocessor. You can use this to
+supply system-specific preprocessor options which GCC does not know how to
+recognize.
+
+If you want to pass an option that takes an argument, you must use
+@option{-Xpreprocessor} twice, once for the option and once for the argument.
+@end table
+
@include cppopts.texi
@node Assembler Options
@opindex Wa
Pass @var{option} as an option to the assembler. If @var{option}
contains commas, it is split into multiple options at the commas.
+
+@item -Xassembler @var{option}
+@opindex Xassembler
+Pass @var{option} as an option to the assembler. You can use this to
+supply system-specific assembler options which GCC does not know how to
+recognize.
+
+If you want to pass an option that takes an argument, you must use
+@option{-Xassembler} twice, once for the option and once for the argument.
+
@end table
@node Link Options
order; the standard system directories come after.
If a standard system include directory, or a directory specified with
-@option{-isystem}, is also specified with @option{-I}, it will be
-searched only in the position requested by @option{-I}. Also, it will
-not be considered a system include directory. If that directory really
-does contain system headers, there is a good chance that they will
-break. For instance, if GCC's installation procedure edited the headers
-in @file{/usr/include} to fix bugs, @samp{-I/usr/include} will cause the
-original, buggy headers to be found instead of the corrected ones. GCC
-will issue a warning when a system include directory is hidden in this
-way.
+@option{-isystem}, is also specified with @option{-I}, the @option{-I}
+option will be ignored. The directory will still be searched but as a
+system directory at its normal position in the system include chain.
+This is to ensure that GCC's procedure to fix buggy system headers and
+the ordering for the include_next directive are not inadvertently changed.
+If you really need to change the search order for system directories,
+use the @option{-nostdinc} and/or @option{-isystem} options.
@item -I-
@opindex I-
simply substituted with a file name chosen for the previous @samp{%u},
without regard to any appended suffix.
-@item %j@var{SUFFIX}
+@item %j@var{suffix}
Substitutes the name of the @code{HOST_BIT_BUCKET}, if any, and if it is
writable, and if save-temps is off; otherwise, substitute the name
of a temporary file, just like @samp{%u}. This temporary file is not
meant for communication between processes, but rather as a junk
disposal mechanism.
+@item %|@var{suffix}
+@itemx %m@var{suffix}
+Like @samp{%g}, except if @option{-pipe} is in effect. In that case
+@samp{%|} substitutes a single dash and @samp{%m} substitutes nothing at
+all. These are the two most common ways to instruct a program that it
+should read from standard input or write to standard output. If you
+need something more elaborate you can use an @samp{%@{pipe:@code{X}@}}
+construct: see for example @file{f/lang-specs.h}.
+
@item %.@var{SUFFIX}
Substitutes @var{.SUFFIX} for the suffixes of a matched switch's args
when it is subsequently output with @samp{%*}. @var{SUFFIX} is
Print @var{str} as an error message. @var{str} is terminated by a newline.
Use this when inconsistent options are detected.
-@item %|
-Output @samp{-} if the input for the current command is coming from a pipe.
-
@item %(@var{name})
Substitute the contents of spec string @var{name} at this point.
Note that each comma in the substituted string is replaced by
a single space.
+@item %<@code{S}
+Remove all occurrences of @code{-S} from the command line. Note---this
+command is position dependent. @samp{%} commands in the spec string
+before this one will see @code{-S}, @samp{%} commands in the spec string
+after this one will not.
+
+@item %:@var{function}(@var{args})
+Call the named function @var{function}, passing it @var{args}.
+@var{args} is first processed as a nested spec string, then split
+into an argument vector in the usual fashion. The function returns
+a string which is processed as if it had appeared literally as part
+of the current spec.
+
+The following built-in spec functions are provided:
+
+@table @code
+@item @code{if-exists}
+The @code{if-exists} spec function takes one argument, an absolute
+pathname to a file. If the file exists, @code{if-exists} returns the
+pathname. Here is a small example of its usage:
+
+@smallexample
+*startfile:
+crt0%O%s %:if-exists(crti%O%s) crtbegin%O%s
+@end smallexample
+
+@item @code{if-exists-else}
+The @code{if-exists-else} spec function is similar to the @code{if-exists}
+spec function, except that it takes two arguments. The first argument is
+an absolute pathname to a file. If the file exists, @code{if-exists-else}
+returns the pathname. If it does not exist, it returns the second argument.
+This way, @code{if-exists-else} can be used to select one file or another,
+based on the existence of the first. Here is a small example of its usage:
+
+@smallexample
+*startfile:
+crt0%O%s %:if-exists(crti%O%s) %:if-exists-else(crtbeginT%O%s crtbegin%O%s)
+@end smallexample
+@end table
+
@item %@{@code{S}@}
Substitutes the @code{-S} switch, if that switch was given to GCC@.
If that switch was not specified, this substitutes nothing. Note that
one switch whose names starts with @samp{o}. %@{o*@} would substitute this
text, including the space. Thus two arguments would be generated.
-@item %@{^@code{S}*@}
-Like %@{@code{S}*@}, but don't put a blank between a switch and its
-argument. Thus %@{^o*@} would only generate one argument, not two.
-
@item %@{@code{S}*&@code{T}*@}
Like %@{@code{S}*@}, but preserve order of @code{S} and @code{T} options
(the order of @code{S} and @code{T} in the spec is not significant).
There can be any number of ampersand-separated variables; for each the
wild card is optional. Useful for CPP as @samp{%@{D*&U*&A*@}}.
-@item %@{<@code{S}@}
-Remove all occurrences of @code{-S} from the command line. Note---this
-command is position dependent. @samp{%} commands in the spec string
-before this option will see @code{-S}, @samp{%} commands in the spec
-string after this option will not.
-
-@item %@{@code{S}*:@code{X}@}
-Substitutes @code{X} if one or more switches whose names start with
-@code{-S} are specified to GCC@. Note that the tail part of the
-@code{-S} option (i.e.@: the part matched by the @samp{*}) will be substituted
-for each occurrence of @samp{%*} within @code{X}.
-
@item %@{@code{S}:@code{X}@}
-Substitutes @code{X}, but only if the @samp{-S} switch was given to GCC@.
+Substitutes @code{X}, if the @samp{-S} switch was given to GCC@.
@item %@{!@code{S}:@code{X}@}
-Substitutes @code{X}, but only if the @samp{-S} switch was @emph{not} given to GCC@.
+Substitutes @code{X}, if the @samp{-S} switch was @emph{not} given to GCC@.
-@item %@{|@code{S}:@code{X}@}
-Like %@{@code{S}:@code{X}@}, but if no @code{S} switch, substitute @samp{-}.
-
-@item %@{|!@code{S}:@code{X}@}
-Like %@{!@code{S}:@code{X}@}, but if there is an @code{S} switch, substitute @samp{-}.
+@item %@{@code{S}*:@code{X}@}
+Substitutes @code{X} if one or more switches whose names start with
+@code{-S} are specified to GCC@. Normally @code{X} is substituted only
+once, no matter how many such switches appeared. However, if @code{%*}
+appears somewhere in @code{X}, then @code{X} will be substituted once
+for each matching switch, with the @code{%*} replaced by the part of
+that switch that matched the @code{*}.
@item %@{.@code{S}:@code{X}@}
-Substitutes @code{X}, but only if processing a file with suffix @code{S}.
+Substitutes @code{X}, if processing a file with suffix @code{S}.
@item %@{!.@code{S}:@code{X}@}
-Substitutes @code{X}, but only if @emph{not} processing a file with suffix @code{S}.
+Substitutes @code{X}, if @emph{not} processing a file with suffix @code{S}.
@item %@{@code{S}|@code{P}:@code{X}@}
-Substitutes @code{X} if either @code{-S} or @code{-P} was given to GCC@. This may be
-combined with @samp{!} and @samp{.} sequences as well, although they
-have a stronger binding than the @samp{|}. For example a spec string
-like this:
+Substitutes @code{X} if either @code{-S} or @code{-P} was given to GCC@.
+This may be combined with @samp{!}, @samp{.}, and @code{*} sequences as well,
+although they have a stronger binding than the @samp{|}. If @code{%*}
+appears in @code{X}, all of the alternatives must be starred, and only
+the first matching alternative is substituted.
+
+For example, a spec string like this:
@smallexample
%@{.c:-foo@} %@{!.c:-bar@} %@{.c|d:-baz@} %@{!.c|d:-boggle@}
-d jim.d -bar -baz -boggle
@end smallexample
+@item %@{S:X; T:Y; :D@}
+
+If @code{S} was given to GCC, substitues @code{X}; else if @code{T} was
+given to GCC, substitues @code{Y}; else substitutes @code{D}. There can
+be as many clauses as you need. This may be combined with @code{.},
+@code{!}, @code{|}, and @code{*} as needed.
+
+
@end table
-The conditional text @code{X} in a %@{@code{S}:@code{X}@} or
-%@{!@code{S}:@code{X}@} construct may contain other nested @samp{%} constructs
-or spaces, or even newlines. They are processed as usual, as described
-above.
+The conditional text @code{X} in a %@{@code{S}:@code{X}@} or similar
+construct may contain other nested @samp{%} constructs or spaces, or
+even newlines. They are processed as usual, as described above.
+Trailing white space in @code{X} is ignored. White space may also
+appear anywhere on the left side of the colon in these constructs,
+except between @code{.} or @code{*} and the corresponding word.
-The @option{-O}, @option{-f}, @option{-m}, and @option{-W}
-switches are handled specifically in these
-constructs. If another value of @option{-O} or the negated form of a @option{-f}, @option{-m}, or
-@option{-W} switch is found later in the command line, the earlier switch
-value is ignored, except with @{@code{S}*@} where @code{S} is just one
-letter, which passes all matching options.
+The @option{-O}, @option{-f}, @option{-m}, and @option{-W} switches are
+handled specifically in these constructs. If another value of
+@option{-O} or the negated form of a @option{-f}, @option{-m}, or
+@option{-W} switch is found later in the command line, the earlier
+switch value is ignored, except with @{@code{S}*@} where @code{S} is
+just one letter, which passes all matching options.
-The character @samp{|} at the beginning of the predicate text is used to indicate
-that a command should be piped to the following command, but only if @option{-pipe}
-is specified.
+The character @samp{|} at the beginning of the predicate text is used to
+indicate that a command should be piped to the following command, but
+only if @option{-pipe} is specified.
It is built into GCC which switches take arguments and which do not.
(You might think it would be useful to generalize this to allow each
* M68hc1x Options::
* VAX Options::
* SPARC Options::
-* Convex Options::
-* AMD29K Options::
* ARM Options::
* MN10200 Options::
* MN10300 Options::
* M32R/D Options::
* M88K Options::
* RS/6000 and PowerPC Options::
+* Darwin Options::
* RT Options::
* MIPS Options::
* i386 and x86-64 Options::
* Intel 960 Options::
* DEC Alpha Options::
* DEC Alpha/VMS Options::
-* Clipper Options::
* H8/300 Options::
* SH Options::
* System V Options::
* PDP-11 Options::
* Xstormy16 Options::
* Xtensa Options::
+* FRV Options::
@end menu
@node M680x0 Options
Enable the use of 68HC12 pre and post auto-increment and auto-decrement
addressing modes.
+@item -minmax
+@itemx -nominmax
+@opindex minmax
+@opindex mnominmax
+Enable the use of 68HC12 min and max instructions.
+
+@item -mlong-calls
+@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
+Treat all calls as being far away (near). If calls are assumed to be
+far away, the compiler will use the @code{call} instruction to
+call a function and the @code{rtc} instruction for returning.
+
@item -mshort
@opindex mshort
Consider type @code{int} to be 16 bits wide, like @code{short int}.
should have 8 byte alignment. This enables the use of pairs of
@code{ldd} and @code{std} instructions for copies in structure
assignment, in place of twice as many @code{ld} and @code{st} pairs.
-However, the use of this changed alignment directly violates the Sparc
+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@.
These two options select the processor for which the code is optimized.
With @option{-mcypress} (the default), the compiler optimizes code for the
-Cypress CY7C602 chip, as used in the SparcStation/SparcServer 3xx series.
-This is also appropriate for the older SparcStation 1, 2, IPX etc.
+Cypress CY7C602 chip, as used in the SPARCStation/SPARCServer 3xx series.
+This is also appropriate for the older SPARCStation 1, 2, IPX etc.
-With @option{-msupersparc} the compiler optimizes code for the SuperSparc cpu, as
-used in the SparcStation 10, 1000 and 2000 series. This flag also enables use
+With @option{-msupersparc} the compiler optimizes code for the SuperSPARC cpu, as
+used in the SPARCStation 10, 1000 and 2000 series. This flag also enables use
of the full SPARC v8 instruction set.
These options are deprecated and will be deleted in a future GCC release.
for machine type @var{cpu_type}. Supported values for @var{cpu_type} are
@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{sparclite},
@samp{hypersparc}, @samp{sparclite86x}, @samp{f930}, @samp{f934},
-@samp{sparclet}, @samp{tsc701}, @samp{v9}, and @samp{ultrasparc}.
+@samp{sparclet}, @samp{tsc701}, @samp{v9}, @samp{ultrasparc}, and
+@samp{ultrasparc3}.
Default instruction scheduling parameters are used for values that select
an architecture and not an implementation. These are @samp{v7}, @samp{v8},
v8: supersparc, hypersparc
sparclite: f930, f934, sparclite86x
sparclet: tsc701
- v9: ultrasparc
+ v9: ultrasparc, ultrasparc3
@end smallexample
@item -mtune=@var{cpu_type}
@option{-mtune=@var{cpu_type}}, but the only useful values are those
that select a particular cpu implementation. Those are @samp{cypress},
@samp{supersparc}, @samp{hypersparc}, @samp{f930}, @samp{f934},
-@samp{sparclite86x}, @samp{tsc701}, and @samp{ultrasparc}.
+@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc}, and
+@samp{ultrasparc3}.
@end table
Otherwise, assume no such offset is present.
@end table
-@node Convex Options
-@subsection Convex Options
-@cindex Convex options
-
-These @samp{-m} options are defined for Convex:
-
-@table @gcctabopt
-@item -mc1
-@opindex mc1
-Generate output for C1. The code will run on any Convex machine.
-The preprocessor symbol @code{__convex__c1__} is defined.
-
-@item -mc2
-@opindex mc2
-Generate output for C2. Uses instructions not available on C1.
-Scheduling and other optimizations are chosen for max performance on C2.
-The preprocessor symbol @code{__convex_c2__} is defined.
-
-@item -mc32
-@opindex mc32
-Generate output for C32xx. Uses instructions not available on C1.
-Scheduling and other optimizations are chosen for max performance on C32.
-The preprocessor symbol @code{__convex_c32__} is defined.
-
-@item -mc34
-@opindex mc34
-Generate output for C34xx. Uses instructions not available on C1.
-Scheduling and other optimizations are chosen for max performance on C34.
-The preprocessor symbol @code{__convex_c34__} is defined.
-
-@item -mc38
-@opindex mc38
-Generate output for C38xx. Uses instructions not available on C1.
-Scheduling and other optimizations are chosen for max performance on C38.
-The preprocessor symbol @code{__convex_c38__} is defined.
-
-@item -margcount
-@opindex margcount
-Generate code which puts an argument count in the word preceding each
-argument list. This is compatible with regular CC, and a few programs
-may need the argument count word. GDB and other source-level debuggers
-do not need it; this info is in the symbol table.
-
-@item -mnoargcount
-@opindex mnoargcount
-Omit the argument count word. This is the default.
-
-@item -mvolatile-cache
-@opindex mvolatile-cache
-Allow volatile references to be cached. This is the default.
-
-@item -mvolatile-nocache
-@opindex mvolatile-nocache
-Volatile references bypass the data cache, going all the way to memory.
-This is only needed for multi-processor code that does not use standard
-synchronization instructions. Making non-volatile references to volatile
-locations will not necessarily work.
-
-@item -mlong32
-@opindex mlong32
-Type long is 32 bits, the same as type int. This is the default.
-
-@item -mlong64
-@opindex mlong64
-Type long is 64 bits, the same as type long long. This option is useless,
-because no library support exists for it.
-@end table
-
-@node AMD29K Options
-@subsection AMD29K Options
-@cindex AMD29K options
-
-These @samp{-m} options are defined for the AMD Am29000:
-
-@table @gcctabopt
-@item -mdw
-@opindex mdw
-@cindex DW bit (29k)
-Generate code that assumes the @code{DW} bit is set, i.e., that byte and
-halfword operations are directly supported by the hardware. This is the
-default.
-
-@item -mndw
-@opindex mndw
-Generate code that assumes the @code{DW} bit is not set.
-
-@item -mbw
-@opindex mbw
-@cindex byte writes (29k)
-Generate code that assumes the system supports byte and halfword write
-operations. This is the default.
-
-@item -mnbw
-@opindex mnbw
-Generate code that assumes the systems does not support byte and
-halfword write operations. @option{-mnbw} implies @option{-mndw}.
-
-@item -msmall
-@opindex msmall
-@cindex memory model (29k)
-Use a small memory model that assumes that all function addresses are
-either within a single 256 KB segment or at an absolute address of less
-than 256k. This allows the @code{call} instruction to be used instead
-of a @code{const}, @code{consth}, @code{calli} sequence.
-
-@item -mnormal
-@opindex mnormal
-Use the normal memory model: Generate @code{call} instructions only when
-calling functions in the same file and @code{calli} instructions
-otherwise. This works if each file occupies less than 256 KB but allows
-the entire executable to be larger than 256 KB@. This is the default.
-
-@item -mlarge
-@opindex mlarge
-Always use @code{calli} instructions. Specify this option if you expect
-a single file to compile into more than 256 KB of code.
-
-@item -m29050
-@opindex m29050
-@cindex processor selection (29k)
-Generate code for the Am29050.
-
-@item -m29000
-@opindex m29000
-Generate code for the Am29000. This is the default.
-
-@item -mkernel-registers
-@opindex mkernel-registers
-@cindex kernel and user registers (29k)
-Generate references to registers @code{gr64-gr95} instead of to
-registers @code{gr96-gr127}. This option can be used when compiling
-kernel code that wants a set of global registers disjoint from that used
-by user-mode code.
-
-Note that when this option is used, register names in @samp{-f} flags
-must use the normal, user-mode, names.
-
-@item -muser-registers
-@opindex muser-registers
-Use the normal set of global registers, @code{gr96-gr127}. This is the
-default.
-
-@item -mstack-check
-@itemx -mno-stack-check
-@opindex mstack-check
-@opindex mno-stack-check
-@cindex stack checks (29k)
-Insert (or do not insert) a call to @code{__msp_check} after each stack
-adjustment. This is often used for kernel code.
-
-@item -mstorem-bug
-@itemx -mno-storem-bug
-@opindex mstorem-bug
-@opindex mno-storem-bug
-@cindex storem bug (29k)
-@option{-mstorem-bug} handles 29k processors which cannot handle the
-separation of a mtsrim insn and a storem instruction (most 29000 chips
-to date, but not the 29050).
-
-@item -mno-reuse-arg-regs
-@itemx -mreuse-arg-regs
-@opindex mno-reuse-arg-regs
-@opindex mreuse-arg-regs
-@option{-mno-reuse-arg-regs} tells the compiler to only use incoming argument
-registers for copying out arguments. This helps detect calling a function
-with fewer arguments than it was declared with.
-
-@item -mno-impure-text
-@itemx -mimpure-text
-@opindex mno-impure-text
-@opindex mimpure-text
-@option{-mimpure-text}, used in addition to @option{-shared}, tells the compiler to
-not pass @option{-assert pure-text} to the linker when linking a shared object.
-
-@item -msoft-float
-@opindex msoft-float
-Generate output containing library calls for floating point.
-@strong{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.
-
-@item -mno-multm
-@opindex mno-multm
-Do not generate multm or multmu instructions. This is useful for some embedded
-systems which do not have trap handlers for these instructions.
-@end table
-
@node ARM Options
@subsection ARM Options
@cindex ARM options
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
misaligned accesses will cause a MMU trap and that it should instead
-synthesise the access as a series of byte accesses. The compiler can
+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.
@opindex mshort-load-words
This are deprecated aliases for @option{-mno-alignment-traps}.
-@item -mbsd
-@opindex mbsd
-This option only applies to RISC iX@. Emulate the native BSD-mode
-compiler. This is the default if @option{-ansi} is not specified.
-
-@item -mxopen
-@opindex mxopen
-This option only applies to RISC iX@. Emulate the native X/Open-mode
-compiler.
-
-@item -mno-symrename
-@opindex mno-symrename
-This option only applies to RISC iX@. Do not run the assembler
-post-processor, @samp{symrename}, after code has been assembled.
-Normally it is necessary to modify some of the standard symbols in
-preparation for linking with the RISC iX C library; this option
-suppresses this pass. The post-processor is never run when the
-compiler is built for cross-compilation.
-
@item -mcpu=@var{name}
@opindex mcpu
This specifies the name of the target ARM processor. GCC uses this name
Include (or omit) additional debugging information (about registers used
in each stack frame) as specified in the 88open Object Compatibility
Standard, ``OCS''@. This extra information allows debugging of code that
-has had the frame pointer eliminated. The default for DG/UX, SVr4, and
-Delta 88 SVr3.2 is to include this information; other 88k configurations
-omit this information by default.
+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.
@item -mocs-frame-position
@opindex 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 DG/UX, SVr4, Delta88 SVr3.2, and BCS configurations use
+function. The SVr4 and Delta88 SVr3.2, and BCS configurations use
@option{-mocs-frame-position}; other 88k configurations have the default
@option{-mno-ocs-frame-position}.
SVr4.
@end enumerate
-@option{-msvr4} is the default for the m88k-motorola-sysv4 and
-m88k-dg-dgux m88k configurations. @option{-msvr3} is the default for all
-other m88k configurations.
+@option{-msvr4} is the default for the m88k-motorola-sysv4 configuration.
+@option{-msvr3} is the default for all other m88k configurations.
@item -mversion-03.00
@opindex mversion-03.00
@table @samp
@item common
-@option{-mno-power}, @option{-mno-powerc}
+@option{-mno-power}, @option{-mno-powerpc}
@item power
@itemx power2
@end table
+@node Darwin Options
+@subsection Darwin Options
+@cindex Darwin options
+@table @gcctabopt
+@item -all_load
+@opindex all_load
+Loads all members of static archive libraries.
+See man ld(1) for more information.
+
+@item -arch_errors_fatal
+@opindex arch_errors_fatal
+Cause the errors having to do with files that have the wrong architecture
+to be fatal.
+
+@item -bind_at_load
+@opindex 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.
+
+@item -bundle
+@opindex bundle
+Produce a Mach-o bundle format file.
+See man ld(1) for more information.
+
+@item -bundle_loader @var{executable}
+@opindex bundle_loader
+This specifies the @var{executable} that will be loading the build
+output file being linked. See man ld(1) for more information.
+
+@item -allowable_client @var{client_name}
+@item -arch_only
+
+@item -client_name
+@item -compatibility_version
+@item -current_version
+@item -dependency-file
+@item -dylib_file
+@item -dylinker_install_name
+@item -dynamic
+@item -dynamiclib
+@item -exported_symbols_list
+@item -filelist
+@item -flat_namespace
+@item -force_cpusubtype_ALL
+@item -force_flat_namespace
+@item -headerpad_max_install_names
+@item -image_base
+@item -init
+@item -install_name
+@item -keep_private_externs
+@item -multi_module
+@item -multiply_defined
+@item -multiply_defined_unused
+@item -noall_load
+@item -nomultidefs
+@item -noprebind
+@item -noseglinkedit
+@item -pagezero_size
+@item -prebind
+@item -prebind_all_twolevel_modules
+@item -private_bundle
+@item -read_only_relocs
+@item -sectalign
+@item -sectobjectsymbols
+@item -whyload
+@item -seg1addr
+@item -sectcreate
+@item -sectobjectsymbols
+@item -sectorder
+@item -seg_addr_table
+@item -seg_addr_table_filename
+@item -seglinkedit
+@item -segprot
+@item -segs_read_only_addr
+@item -segs_read_write_addr
+@item -single_module
+@item -static
+@item -sub_library
+@item -sub_umbrella
+@item -twolevel_namespace
+@item -umbrella
+@item -undefined
+@item -unexported_symbols_list
+@item -weak_reference_mismatches
+@item -whatsloaded
+
+@opindex allowable_client
+@opindex arch_only
+@opindex client_name
+@opindex compatibility_version
+@opindex current_version
+@opindex dependency-file
+@opindex dylib_file
+@opindex dylinker_install_name
+@opindex dynamic
+@opindex dynamiclib
+@opindex exported_symbols_list
+@opindex filelist
+@opindex flat_namespace
+@opindex force_cpusubtype_ALL
+@opindex force_flat_namespace
+@opindex headerpad_max_install_names
+@opindex image_base
+@opindex init
+@opindex install_name
+@opindex keep_private_externs
+@opindex multi_module
+@opindex multiply_defined
+@opindex multiply_defined_unused
+@opindex noall_load
+@opindex nomultidefs
+@opindex noprebind
+@opindex noseglinkedit
+@opindex pagezero_size
+@opindex prebind
+@opindex prebind_all_twolevel_modules
+@opindex private_bundle
+@opindex read_only_relocs
+@opindex sectalign
+@opindex sectobjectsymbols
+@opindex whyload
+@opindex seg1addr
+@opindex sectcreate
+@opindex sectobjectsymbols
+@opindex sectorder
+@opindex seg_addr_table
+@opindex seg_addr_table_filename
+@opindex seglinkedit
+@opindex segprot
+@opindex segs_read_only_addr
+@opindex segs_read_write_addr
+@opindex single_module
+@opindex static
+@opindex sub_library
+@opindex sub_umbrella
+@opindex twolevel_namespace
+@opindex umbrella
+@opindex undefined
+@opindex unexported_symbols_list
+@opindex weak_reference_mismatches
+@opindex whatsloaded
+
+This options are available for Darwin linker. Darwin linker man page
+describes them in detail.
+@end table
+
+
@node RT Options
@subsection IBM RT Options
@cindex RT options
GCC defines two macros based on the value of this option. The first
is @samp{_MIPS_ARCH}, which gives the name of target architecture, as
a string. The second has the form @samp{_MIPS_ARCH_@var{foo}},
-where @var{foo} is the capitialized value of @samp{_MIPS_ARCH}@.
+where @var{foo} is the capitalized value of @samp{_MIPS_ARCH}@.
For example, @samp{-march=r2000} will set @samp{_MIPS_ARCH}
to @samp{"r2000"} and define the macro @samp{_MIPS_ARCH_R2000}.
memory range, and the number 3 (to flush both caches). The default
depends on the target gcc was configured for, but commonly is either
@samp{_flush_func} or @samp{__cpu_flush}.
-@end table
-These options are defined by the macro
-@code{TARGET_SWITCHES} in the machine description. The default for the
-options is also defined by that macro, which enables you to change the
-defaults.
+@item -mbranch-likely
+@itemx -mno-branch-likely
+@opindex mbranch-likely
+@opindex mno-branch-likely
+Enable or disable use of Branch Likely instructions, regardless of the
+default for the selected architecture. By default, Branch Likely
+instructions may be generated if they are supported by the selected
+architecture. An exception is for the MIPS32 and MIPS64 architectures
+and processors which implement those architectures; for those, Branch
+Likely instructions will not be generated by default because the MIPS32
+and MIPS64 architectures specifically deprecate their use.
+@end table
@node i386 and x86-64 Options
@subsection Intel 386 and AMD x86-64 Options
@var{cpu-type} are @samp{i386}, @samp{i486}, @samp{i586}, @samp{i686},
@samp{pentium}, @samp{pentium-mmx}, @samp{pentiumpro}, @samp{pentium2},
@samp{pentium3}, @samp{pentium4}, @samp{k6}, @samp{k6-2}, @samp{k6-3},
-@samp{athlon}, @samp{athlon-tbird}, @samp{athlon-4}, @samp{athlon-xp}
-and @samp{athlon-mp}.
+@samp{athlon}, @samp{athlon-tbird}, @samp{athlon-4}, @samp{athlon-xp},
+@samp{athlon-mp}, @samp{winchip-c6}, @samp{winchip2}, @samp{k8} and @samp{c3}.
While picking a specific @var{cpu-type} will schedule things appropriately
for that particular chip, the compiler will not generate any code that
@item 387
Use the standard 387 floating point coprocessor present majority of chips and
emulated otherwise. Code compiled with this option will run almost everywhere.
-The temporary results are computed in 80bit precesion instead of precision
+The temporary results are computed in 80bit precision instead of precision
specified by the type resulting in slightly different results compared to most
of other chips. See @option{-ffloat-store} for more detailed description.
This is the default choice for x86-64 compiler.
@item sse,387
-Attempt to utilize both instruction sets at once. This effectivly double the
+Attempt to utilize both instruction sets at once. This effectively double the
amount of available registers and on chips with separate execution units for
387 and SSE the execution resources too. Use this option with care, as it is
still experimental, because gcc register allocator does not model separate
produce code that runs somewhat faster on a @samp{Pentium} at the
expense of more memory.
-@strong{Warning:} if you use the @samp{-malign-double} switch,
+@strong{Warning:} if you use the @option{-malign-double} switch,
structures containing the above types will be aligned differently than
-the published application binary interface specifications for the 386.
+the published application binary interface specifications for the 386
+and will not be binary compatible with structures in code compiled
+without that switch.
@item -m128bit-long-double
@opindex m128bit-long-double
@xref{X86 Built-in Functions}, for details of the functions enabled
and disabled by these switches.
+To have SSE/SSE2 instructions generated automatically from floating-point
+code, see @option{-mfpmath=sse}.
+
@item -mpush-args
@itemx -mno-push-args
@opindex mpush-args
stack pointer that will not be modified by signal or interrupt handlers
and therefore can be used for temporary data without adjusting the stack
pointer. The flag @option{-mno-red-zone} disables this red zone.
+
+@item -mcmodel=small
+@opindex 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.
+
+@item -mcmodel=kernel
+@opindex 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.
+
+@item -mcmodel=medium
+@opindex mcmodel=medium
+Generate code for the medium model: The program is linked in the lower 2
+GB of the address space but symbols 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.
+
+@item -mcmodel=large
+@opindex 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.
@end table
@node HPPA Options
@item -mlinker-opt
@opindex mlinker-opt
-Enable the optimization pass in the HPUX linker. Note this makes symbolic
-debugging impossible. It also triggers a bug in the HPUX 8 and HPUX 9 linkers
-in which they give bogus error messages when linking some programs.
+Enable the optimization pass in the HP-UX linker. 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.
@item -msoft-float
@opindex msoft-float
this option. In particular, you need to compile @file{libgcc.a}, the
library that comes with GCC, with @option{-msoft-float} in order for
this to work.
+
+@item -msio
+@opindex msio
+Generate the predefine, @code{_SIO}, for server IO. The default is
+@option{-mwsio}. This generates the predefines, @code{__hp9000s700},
+@code{__hp9000s700__} and @code{_WSIO}, for workstation IO. These
+options are available under HP-UX and HI-UX.
+
+@item -mgnu-ld
+@opindex gnu-ld
+Use GNU ld specific options. This passes @option{-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
+@option{--with-ld} configure option, gcc's program search path, and
+finally by the user's @env{PATH}. The linker used by GCC can be printed
+using @samp{which `gcc -print-prog-name=ld`}.
+
+@item -mhp-ld
+@opindex hp-ld
+Use HP ld specific options. This passes @option{-b} to ld when building
+a shared library and passes @option{+Accept TypeMismatch} to ld on all
+links. It is the default when GCC is configured, explicitly or
+implicitly, with the HP linker. This option does not have any affect on
+which ld is called, it only changes what parameters are passed to that
+ld. The ld that is called is determined by the @option{--with-ld}
+configure option, gcc's program search path, and finally by the user's
+@env{PATH}. The linker used by GCC can be printed using @samp{which
+`gcc -print-prog-name=ld`}.
+
+@item -mlong-calls
+@opindex mno-long-calls
+Generate code that uses long call sequences. This ensures that a call
+is always able to reach linker generated stubs. The default is to generate
+long calls only when the distance from the call site to the beginning
+of the function or translation unit, as the case may be, exceeds a
+predefined limit set by the branch type being used. The limits for
+normal calls are 7,600,000 and 240,000 bytes, respectively for the
+PA 2.0 and PA 1.X architectures. Sibcalls are always limited at
+240,000 bytes.
+
+Distances are measured from the beginning of functions when using the
+@option{-ffunction-sections} option, or when using the @option{-mgas}
+and @option{-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 linking is used to build the application.
+
+The types of long calls used depends on the capabilities 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.
+However, an indirect call is used on 32-bit ELF systems in pic code
+and it is quite long.
+
@end table
@node Intel 960 Options
@opindex mno-explicit-relocs
Older Alpha assemblers provided no way to generate symbol relocations
except via assembler macros. Use of these macros does not allow
-optimial instruction scheduling. GNU binutils as of version 2.12
+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 instructions. This option
is mostly useful for debugging, as GCC detects the capabilities of
When generating code for shared libraries, @option{-fpic} implies
@option{-msmall-data} and @option{-fPIC} implies @option{-mlarge-data}.
+@item -msmall-text
+@itemx -mlarge-text
+@opindex msmall-text
+@opindex mlarge-text
+When @option{-msmall-text} is used, the compiler assumes that the
+code of the entire program (or shared library) fits in 4MB, and is
+thus reachable with a branch instruction. When @option{-msmall-data}
+is used, the compiler can assume that all local symbols share the
+same @code{$gp} value, and thus reduce the number of instructions
+required for a function call from 4 to 1.
+
+The default is @option{-mlarge-text}.
+
@item -mcpu=@var{cpu_type}
@opindex mcpu
Set the instruction set and instruction scheduling parameters for
style condition (e.g.@ error) codes.
@end table
-@node Clipper Options
-@subsection Clipper Options
-
-These @samp{-m} options are defined for the Clipper implementations:
-
-@table @gcctabopt
-@item -mc300
-@opindex mc300
-Produce code for a C300 Clipper processor. This is the default.
-
-@item -mc400
-@opindex mc400
-Produce code for a C400 Clipper processor, i.e.@: use floating point
-registers f8--f15.
-@end table
-
@node H8/300 Options
@subsection H8/300 Options
@item -ms
@opindex ms
-Generate code for the H8/S@.
+Generate code for the H8S@.
+
+@item -mn
+@opindex mn
+Generate code for the H8S and H8/300H in the normal mode. This switch
+must be used either with -mh or -ms.
@item -ms2600
@opindex ms2600
-Generate code for the H8/S2600. This switch must be used with @option{-ms}.
+Generate code for the H8S/2600. This switch must be used with @option{-ms}.
@item -mint32
@opindex mint32
@item -malign-300
@opindex malign-300
-On the H8/300H and H8/S, use the same alignment rules as for the H8/300.
-The default for the H8/300H and H8/S is to align longs and floats on 4
+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.
@option{-malign-300} causes them to be aligned on 2 byte boundaries.
This option has no effect on the H8/300.
on the safe side, this is disabled for the C3x, since the maximum
iteration count on the C3x is @math{2^{23} + 1} (but who iterates loops more than
@math{2^{23}} times on the C3x?). Note that GCC will try to reverse a loop so
-that it can utilise the decrement and branch instruction, but will give
+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 the RPTB instruction cannot be utilised.
+efficient code, in cases where the RPTB instruction cannot be utilized.
@item -mdp-isr-reload
@itemx -mparanoid
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.
+
+@item -mapp-regs
+@opindex -mapp-regs
+This option will cause r2 and r5 to be used in the code generated by
+the compiler. This setting is the default.
+
+@item -mno-app-regs
+@opindex -mno-app-regs
+This option will cause r2 and r5 to be treated as fixed registers.
+
+@item -mv850e
+@opindex -mv850e
+Specify that the target processor is the V850E. The preprocessor
+constant @samp{__v850e__} will be defined if this option is used.
+
+If neither @option{-mv850} nor @option{-mv850e} are defined
+then a default target processor will be chosen and the relevant
+@samp{__v850*__} preprocessor constant will be defined.
+
+The preprocessor constants @samp{__v850} and @samp{__v851__} are always
+defined, regardless of which processor variant is the target.
+
+@item -mdisable-callt
+@opindex -mdisable-callt
+This option will suppress generation of the CALLT instruction for the
+v850e flavors of the v850 architecture. The default is
+@option{-mno-disable-callt} which allows the CALLT instruction to be used.
+
@end table
@node ARC Options
@table @gcctabopt
@item -mbig-endian
@opindex mbig-endian
-Generate code for a big endian target. This is the default for HPUX@.
+Generate code for a big endian target. This is the default for HP-UX@.
@item -mlittle-endian
@opindex mlittle-endian
Generate code that is self-relocatable. This implies @option{-mconstant-gp}.
This is useful when compiling firmware code.
-@item -minline-divide-min-latency
-@opindex minline-divide-min-latency
-Generate code for inline divides using the minimum latency algorithm.
+@item -minline-float-divide-min-latency
+@opindex minline-float-divide-min-latency
+Generate code for inline divides of floating point values
+using the minimum latency algorithm.
+
+@item -minline-float-divide-max-throughput
+@opindex minline-float-divide-max-throughput
+Generate code for inline divides of floating point values
+using the maximum throughput algorithm.
-@item -minline-divide-max-throughput
-@opindex minline-divide-max-throughput
-Generate code for inline divides using the maximum throughput algorithm.
+@item -minline-int-divide-min-latency
+@opindex minline-int-divide-min-latency
+Generate code for inline divides of integer values
+using the minimum latency algorithm.
+
+@item -minline-int-divide-max-throughput
+@opindex minline-int-divide-max-throughput
+Generate code for inline divides of integer values
+using the maximum throughput algorithm.
@item -mno-dwarf2-asm
@itemx -mdwarf2-asm
targets, the default is @option{-m31}, while the @samp{s390x}
targets default to @option{-m64}.
+@item -mzarch
+@itemx -mesa
+@opindex mzarch
+@opindex mesa
+When @option{-mzarch} is specified, generate code using the
+instructions available on z/Architecture.
+When @option{-mesa} is specified, generate code using the
+instructions available on ESA/390. Note that @option{-mesa} is
+not possible with @option{-m64}.
+For the @samp{s390} targets, the default is @option{-mesa},
+while the @samp{s390x} targets default to @option{-mzarch}.
+
@item -mmvcle
@itemx -mno-mvcle
@opindex mmvcle
@opindex mno-mvcle
Generate (or do not generate) code using the @code{mvcle} instruction
-to perform block moves. When @option{-mno-mvcle} is specifed,
+to perform block moves. When @option{-mno-mvcle} is specified,
use a @code{mvc} loop instead. This is the default.
@item -mdebug
Print (or do not print) additional debug information when compiling.
The default is to not print debug information.
+@item -march=@var{arch}
+@opindex march
+Generate code that will run on @var{arch}, which is the name of system
+representing a certain processor type. Possible values for
+@var{cpu-type} are @samp{g5}, @samp{g6} and @samp{z900}.
+
+@item -mcpu=@var{arch}
+@opindex mcpu
+Tune to @var{cpu-type} everything applicable about the generated code,
+ except for the ABI and the set of available instructions.
+The list of @var{arch} values is the same as for @option{-march}.
+
@end table
@node CRIS Options
Choose startup files and linker script suitable for the simulator.
@end table
+@node FRV Options
+@subsection FRV Options
+@cindex FRV Options
+
+@table @gcctabopt
+@item -mgpr-32
+@opindex mgpr-32
+
+Only use the first 32 general purpose registers.
+
+@item -mgpr-64
+@opindex mgpr-64
+
+Use all 64 general purpose registers.
+
+@item -mfpr-32
+@opindex mfpr-32
+
+Use only the first 32 floating point registers.
+
+@item -mfpr-64
+@opindex mfpr-64
+
+Use all 64 floating point registers
+
+@item -mhard-float
+@opindex mhard-float
+
+Use hardware instructions for floating point operations.
+
+@item -msoft-float
+@opindex msoft-float
+
+Use library routines for floating point operations.
+
+@item -malloc-cc
+@opindex malloc-cc
+
+Dynamically allocate condition code registers.
+
+@item -mfixed-cc
+@opindex mfixed-cc
+
+Do not try to dynamically allocate condition code registers, only
+use @code{icc0} and @code{fcc0}.
+
+@item -mdword
+@opindex mdword
+
+Change ABI to use double word insns.
+
+@item -mno-dword
+@opindex mno-dword
+
+Do not use double word instructions.
+
+@item -mdouble
+@opindex mdouble
+
+Use floating point double instructions.
+
+@item -mno-double
+@opindex mno-double
+
+Do not use floating point double instructions.
+
+@item -mmedia
+@opindex mmedia
+
+Use media instructions.
+
+@item -mno-media
+@opindex mno-media
+
+Do not use media instructions.
+
+@item -mmuladd
+@opindex mmuladd
+
+Use multiply and add/subtract instructions.
+
+@item -mno-muladd
+@opindex mno-muladd
+
+Do not use multiply and add/subtract instructions.
+
+@item -mlibrary-pic
+@opindex mlibrary-pic
+
+Enable PIC support for building libraries
+
+@item -macc-4
+@opindex macc-4
+
+Use only the first four media accumulator registers.
+
+@item -macc-8
+@opindex macc-8
+
+Use all eight media accumulator registers.
+
+@item -mpack
+@opindex mpack
+
+Pack VLIW instructions.
+
+@item -mno-pack
+@opindex mno-pack
+
+Do not pack VLIW instructions.
+
+@item -mno-eflags
+@opindex mno-eflags
+
+Do not mark ABI switches in e_flags.
+
+@item -mcond-move
+@opindex 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.
+
+@item -mno-cond-move
+@opindex 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.
+
+@item -mscc
+@opindex mscc
+
+Enable the use of conditional set instructions (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-scc
+@opindex mno-scc
+
+Disable the use of conditional set instructions.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mcond-exec
+@opindex mcond-exec
+
+Enable the use of conditional execution (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-cond-exec
+@opindex 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.
+
+@item -mvliw-branch
+@opindex 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.
+
+@item -mno-vliw-branch
+@opindex mno-vliw-branch
+
+Do not run a pass to pack branches into VLIW instructions.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mmulti-cond-exec
+@opindex mmulti-cond-exec
+
+Enable optimization of @code{&&} and @code{||} in conditional execution
+(default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-multi-cond-exec
+@opindex mno-multi-cond-exec
+
+Disable optimization of @code{&&} and @code{||} in conditional execution.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mnested-cond-exec
+@opindex 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.
+
+@item -mno-nested-cond-exec
+@opindex 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.
+
+@item -mtomcat-stats
+@opindex mtomcat-stats
+
+Cause gas to print out tomcat statistics.
+
+@item -mcpu=@var{cpu}
+@opindex mcpu
+
+Select the processor type for which to generate code. Possible values are
+@samp{simple}, @samp{tomcat}, @samp{fr500}, @samp{fr400}, @samp{fr300},
+@samp{frv}.
+
+@end table
+
@node Xtensa Options
@subsection Xtensa Options
@cindex Xtensa Options
Return ``short'' @code{struct} and @code{union} values in memory like
longer ones, rather than in registers. This convention is less
efficient, but it has the advantage of allowing intercallability between
-GCC-compiled files and files compiled with other compilers.
+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.
+@strong{Warning:} code compiled with the @option{-fpcc-struct-return}
+switch is not binary compatible with code compiled with the
+@option{-freg-struct-return} switch.
+Use it to conform to a non-default application binary interface.
+
@item -freg-struct-return
@opindex freg-struct-return
Return @code{struct} and @code{union} values in registers when possible.
the principal compiler. In those cases, we can choose the standard, and
we chose the more efficient register return alternative.
+@strong{Warning:} code compiled with the @option{-freg-struct-return}
+switch is not binary compatible with code compiled with the
+@option{-fpcc-struct-return} switch.
+Use it to conform to a non-default application binary interface.
+
@item -fshort-enums
@opindex fshort-enums
Allocate to an @code{enum} type only as many bytes as it needs for the
declared range of possible values. Specifically, the @code{enum} type
will be equivalent to the smallest integer type which has enough room.
+@strong{Warning:} the @option{-fshort-enums} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
@item -fshort-double
@opindex fshort-double
Use the same size for @code{double} as for @code{float}.
+@strong{Warning:} the @option{-fshort-double} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
+@item -fshort-wchar
+@opindex fshort-wchar
+Override the underlying type for @samp{wchar_t} to be @samp{short
+unsigned int} instead of the default for the target. This option is
+useful for building programs to run under WINE@.
+
+@strong{Warning:} the @option{-fshort-wchar} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
@item -fshared-data
@opindex fshared-data
Requests that the data and non-@code{const} variables of this
the GOT size for the linked executable exceeds a machine-specific
maximum size, you get an error message from the linker indicating that
@option{-fpic} does not work; in that case, recompile with @option{-fPIC}
-instead. (These maximums are 16k on the m88k, 8k on the Sparc, and 32k
+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
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.
+and the SPARC.
Position-independent code requires special support, and therefore works
only on certain machines.
@item -fpack-struct
@opindex fpack-struct
-Pack all structure members together without holes. Usually you would
-not want to use this option, since it makes the code suboptimal, and
-the offsets of structure members won't agree with system libraries.
+Pack all structure members together without holes.
+
+@strong{Warning:} the @option{-fpack-struct} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Additionally, it makes the code suboptimal.
+Use it to conform to a non-default application binary interface.
@item -finstrument-functions
@opindex finstrument-functions
change the way C symbols are represented in the object file. One use
is to help link with legacy assembly code.
-Be warned that you should know what you are doing when invoking this
-option, and that not all targets provide complete support for it.
+@strong{Warning:} the @option{-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.
@item -ftls-model=@var{model}
Alter the thread-local storage model to be used (@pxref{Thread-Local}).
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