@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
@c Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@table @emph
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
-@gccoptlist{-c -S -E -o @var{file} -combine -no-canonical-prefixes @gol
+@gccoptlist{-c -S -E -o @var{file} -no-canonical-prefixes @gol
-pipe -pass-exit-codes @gol
-x @var{language} -v -### --help@r{[}=@var{class}@r{[},@dots{}@r{]]} --target-help @gol
---version -wrapper@@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg} @gol
--fdump-ada-spec@r{[}-slim@r{]}}
+--version -wrapper @@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg} @gol
+-fdump-ada-spec@r{[}-slim@r{]}} -fdump-go-spec=@var{file}
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@gccoptlist{-ansi -std=@var{standard} -fgnu89-inline @gol
-aux-info @var{filename} @gol
-fno-asm -fno-builtin -fno-builtin-@var{function} @gol
--fhosted -ffreestanding -fopenmp -fms-extensions @gol
+-fhosted -ffreestanding -fopenmp -fms-extensions -fplan9-extensions @gol
-trigraphs -no-integrated-cpp -traditional -traditional-cpp @gol
-fallow-single-precision -fcond-mismatch -flax-vector-conversions @gol
-fsigned-bitfields -fsigned-char @gol
@item C++ Language Options
@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@gccoptlist{-fabi-version=@var{n} -fno-access-control -fcheck-new @gol
--fconserve-space -ffriend-injection @gol
+-fconserve-space -fconstexpr-depth=@var{n} -ffriend-injection @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
-ffor-scope -fno-for-scope -fno-gnu-keywords @gol
@gccoptlist{-fconstant-string-class=@var{class-name} @gol
-fgnu-runtime -fnext-runtime @gol
-fno-nil-receivers @gol
+-fobjc-abi-version=@var{n} @gol
-fobjc-call-cxx-cdtors @gol
-fobjc-direct-dispatch @gol
-fobjc-exceptions @gol
-fobjc-gc @gol
+-fobjc-nilcheck @gol
+-fobjc-std=objc1 @gol
-freplace-objc-classes @gol
-fzero-link @gol
-gen-decls @gol
@xref{Language Independent Options,,Options to Control Diagnostic Messages Formatting}.
@gccoptlist{-fmessage-length=@var{n} @gol
-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]} @gol
--fdiagnostics-show-option}
+-fno-diagnostics-show-option}
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
-@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @gol
+@gccoptlist{-fsyntax-only -fmax-errors=@var{n} -pedantic @gol
+-pedantic-errors @gol
-w -Wextra -Wall -Waddress -Waggregate-return -Warray-bounds @gol
-Wno-attributes -Wno-builtin-macro-redefined @gol
-Wc++-compat -Wc++0x-compat -Wcast-align -Wcast-qual @gol
-Wchar-subscripts -Wclobbered -Wcomment @gol
-Wconversion -Wcoverage-mismatch -Wcpp -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization @gol
--Wno-div-by-zero -Wempty-body -Wenum-compare -Wno-endif-labels @gol
--Werror -Werror=* @gol
+-Wno-div-by-zero -Wdouble-promotion -Wempty-body -Wenum-compare @gol
+-Wno-endif-labels -Werror -Werror=* @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral @gol
-Wformat-security -Wformat-y2k @gol
-Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef @gol
-Wuninitialized -Wunknown-pragmas -Wno-pragmas @gol
-Wunsuffixed-float-constants -Wunused -Wunused-function @gol
--Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value -Wunused-variable @gol
--Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros -Wvla @gol
--Wvolatile-register-var -Wwrite-strings}
+-Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value @gol
+-Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable @gol
+-Wvariadic-macros -Wvla -Wvolatile-register-var -Wwrite-strings}
@item C and Objective-C-only Warning Options
@gccoptlist{-Wbad-function-cast -Wmissing-declarations @gol
-fcompare-debug@r{[}=@var{opts}@r{]} -fcompare-debug-second @gol
-feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
-feliminate-unused-debug-symbols -femit-class-debug-always @gol
--fenable-icf-debug @gol
-fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report -fprofile-arcs @gol
-frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol
--ftest-coverage -ftime-report -fvar-tracking @gol
+-fstack-usage -ftest-coverage -ftime-report -fvar-tracking @gol
-fvar-tracking-assignments -fvar-tracking-assignments-toggle @gol
-g -g@var{level} -gtoggle -gcoff -gdwarf-@var{version} @gol
-ggdb -gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf @gol
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-@gccoptlist{
--falign-functions[=@var{n}] -falign-jumps[=@var{n}] @gol
+@gccoptlist{-falign-functions[=@var{n}] -falign-jumps[=@var{n}] @gol
-falign-labels[=@var{n}] -falign-loops[=@var{n}] -fassociative-math @gol
-fauto-inc-dec -fbranch-probabilities -fbranch-target-load-optimize @gol
-fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves @gol
--fcheck-data-deps -fconserve-stack -fcprop-registers -fcrossjumping @gol
--fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules -fcx-limited-range @gol
--fdata-sections -fdce -fdce @gol
--fdelayed-branch -fdelete-null-pointer-checks -fdse -fdse @gol
+-fcheck-data-deps -fcombine-stack-adjustments -fconserve-stack @gol
+-fcompare-elim -fcprop-registers -fcrossjumping @gol
+-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules @gol
+-fcx-limited-range @gol
+-fdata-sections -fdce -fdce -fdelayed-branch @gol
+-fdelete-null-pointer-checks -fdse -fdevirtualize -fdse @gol
-fearly-inlining -fipa-sra -fexpensive-optimizations -ffast-math @gol
-ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
--fforward-propagate -ffunction-sections @gol
+-fforward-propagate -ffp-contract=@var{style} -ffunction-sections @gol
-fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity @gol
-fgcse-sm -fif-conversion -fif-conversion2 -findirect-inlining @gol
-finline-functions -finline-functions-called-once -finline-limit=@var{n} @gol
--finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg -fipa-pta @gol
--fipa-profile -fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
--fira-algorithm=@var{algorithm} @gol
--fira-region=@var{region} -fira-coalesce @gol
+-finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg @gol
+-fipa-pta -fipa-profile -fipa-pure-const -fipa-reference @gol
+-fipa-struct-reorg -fira-algorithm=@var{algorithm} @gol
+-fira-region=@var{region} @gol
-fira-loop-pressure -fno-ira-share-save-slots @gol
-fno-ira-share-spill-slots -fira-verbose=@var{n} @gol
-fivopts -fkeep-inline-functions -fkeep-static-consts @gol
--floop-block -floop-interchange -floop-strip-mine @gol
--floop-parallelize-all -flto -flto-compression-level -flto-report -fltrans @gol
--fltrans-output-list -fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
--fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
--fmudflapir -fmudflapth -fno-branch-count-reg -fno-default-inline @gol
+-floop-block -floop-flatten -floop-interchange -floop-strip-mine @gol
+-floop-parallelize-all -flto -flto-compression-level
+-flto-partition=@var{alg} -flto-report -fmerge-all-constants @gol
+-fmerge-constants -fmodulo-sched -fmodulo-sched-allow-regmoves @gol
+-fmove-loop-invariants fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
+-fno-default-inline @gol
-fno-defer-pop -fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
-fno-sched-interblock -fno-sched-spec -fno-signed-zeros @gol
-fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
-fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls @gol
--fpartial-inlining -fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
+-fpartial-inlining -fpeel-loops -fpredictive-commoning @gol
+-fprefetch-loop-arrays @gol
-fprofile-correction -fprofile-dir=@var{path} -fprofile-generate @gol
-fprofile-generate=@var{path} @gol
-fprofile-use -fprofile-use=@var{path} -fprofile-values @gol
-fsel-sched-pipelining -fsel-sched-pipelining-outer-loops @gol
-fsignaling-nans -fsingle-precision-constant -fsplit-ivs-in-unroller @gol
-fsplit-wide-types -fstack-protector -fstack-protector-all @gol
--fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer -ftree-bit-ccp @gol
+-fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer @gol
+-ftree-bit-ccp @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop @gol
-ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse @gol
--ftree-forwprop -ftree-fre -ftree-loop-if-convert -ftree-loop-im @gol
+-ftree-forwprop -ftree-fre -ftree-loop-if-convert @gol
+-ftree-loop-if-convert-stores -ftree-loop-im @gol
-ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol
-funit-at-a-time -funroll-all-loops -funroll-loops @gol
-funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
--fwhole-program -fwhopr[=@var{n}] -fwpa -fuse-linker-plugin @gol
+-fwhole-program -fwpa -fuse-linker-plugin @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os -Ofast}
-mno-fp-ret-in-387 -msoft-float @gol
-mno-wide-multiply -mrtd -malign-double @gol
-mpreferred-stack-boundary=@var{num}
--mincoming-stack-boundary=@var{num}
--mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip @gol
+-mincoming-stack-boundary=@var{num} @gol
+-mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip -mvzeroupper @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @gol
-maes -mpclmul -mfsgsbase -mrdrnd -mf16c -mfused-madd @gol
--msse4a -m3dnow -mpopcnt -mabm -mfma4 -mxop -mlwp @gol
+-msse4a -m3dnow -mpopcnt -mabm -mbmi -mtbm -mfma4 -mxop -mlwp @gol
-mthreads -mno-align-stringops -minline-all-stringops @gol
-minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -msseregparm @gol
--mveclibabi=@var{type} -mpc32 -mpc64 -mpc80 -mstackrealign @gol
+-mveclibabi=@var{type} -mvect8-ret-in-mem @gol
+-mpc32 -mpc64 -mpc80 -mstackrealign @gol
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
-mcmodel=@var{code-model} -mabi=@var{name} @gol
-m32 -m64 -mlarge-data-threshold=@var{num} @gol
--msse2avx -mfentry}
+-msse2avx -mfentry -m8bit-idiv}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
-mmult -mno-opts -mrepeat -ms -msatur -msdram -msim -msimnovec -mtf @gol
-mtiny=@var{n}}
+@emph{MicroBlaze Options}
+@gccoptlist{-msoft-float -mhard-float -msmall-divides -mcpu=@var{cpu} @gol
+-mmemcpy -mxl-soft-mul -mxl-soft-div -mxl-barrel-shift @gol
+-mxl-pattern-compare -mxl-stack-check -mxl-gp-opt -mno-clearbss @gol
+-mxl-multiply-high -mxl-float-convert -mxl-float-sqrt @gol
+-mxl-mode-@var{app-model}}
+
@emph{MIPS Options}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 @gol
@emph{MN10300 Options}
@gccoptlist{-mmult-bug -mno-mult-bug @gol
--mam33 -mno-am33 @gol
--mam33-2 -mno-am33-2 @gol
+-mno-am33 -mam33 -mam33-2 -mam34 @gol
+-mtune=@var{cpu-type} @gol
-mreturn-pointer-on-d0 @gol
--mno-crt0 -mrelax}
+-mno-crt0 -mrelax -mliw}
@emph{PDP-11 Options}
@gccoptlist{-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 @gol
-mint16 -mno-int32 -mfloat32 -mno-float64 @gol
-mfloat64 -mno-float32 -mabshi -mno-abshi @gol
-mbranch-expensive -mbranch-cheap @gol
--msplit -mno-split -munix-asm -mdec-asm}
+-munix-asm -mdec-asm}
@emph{picoChip Options}
-@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N}
+@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N} @gol
-msymbol-as-address -mno-inefficient-warnings}
@emph{PowerPC Options}
-mstrict-align -mno-strict-align -mrelocatable @gol
-mno-relocatable -mrelocatable-lib -mno-relocatable-lib @gol
-mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian @gol
--mdynamic-no-pic -maltivec -mswdiv @gol
+-mdynamic-no-pic -maltivec -mswdiv -msingle-pic-base @gol
-mprioritize-restricted-insns=@var{priority} @gol
-msched-costly-dep=@var{dependence_type} @gol
-minsert-sched-nops=@var{scheme} @gol
-msdata=@var{opt} -mvxworks -G @var{num} -pthread @gol
-mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision
-mno-recip-precision @gol
--mveclibabi=@var{type}}
+-mveclibabi=@var{type} -mfriz -mno-friz}
@emph{RX Options}
@gccoptlist{-m64bit-doubles -m32bit-doubles -fpu -nofpu@gol
-madjust-unroll -mindexed-addressing -mgettrcost=@var{number} -mpt-fixed @gol
-maccumulate-outgoing-args -minvalid-symbols}
+@emph{Solaris 2 Options}
+@gccoptlist{-mimpure-text -mno-impure-text @gol
+-pthreads -pthread}
+
@emph{SPARC Options}
@gccoptlist{-mcpu=@var{cpu-type} @gol
-mtune=@var{cpu-type} @gol
-mfaster-structs -mno-faster-structs @gol
-mfpu -mno-fpu -mhard-float -msoft-float @gol
-mhard-quad-float -msoft-quad-float @gol
--mimpure-text -mno-impure-text -mlittle-endian @gol
+-mlittle-endian @gol
-mstack-bias -mno-stack-bias @gol
-munaligned-doubles -mno-unaligned-doubles @gol
--mv8plus -mno-v8plus -mvis -mno-vis
--threads -pthreads -pthread}
+-mv8plus -mno-v8plus -mvis -mno-vis}
@emph{SPU Options}
@gccoptlist{-mwarn-reloc -merror-reloc @gol
-mdisable-callt -mno-disable-callt @gol
-mv850e2v3 @gol
-mv850e2 @gol
--mv850e1 @gol
+-mv850e1 -mv850es @gol
-mv850e @gol
-mv850 -mbig-switch}
@emph{i386 and x86-64 Windows Options}
@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll
--mnop-fun-dllimport -mthread -municode -mwin32 -mwindows
--fno-set-stack-executable}
+-mnop-fun-dllimport -mthread @gol
+-municode -mwin32 -mwindows -fno-set-stack-executable}
@emph{Xstormy16 Options}
@gccoptlist{-msim}
-fshort-double -fshort-wchar @gol
-fverbose-asm -fpack-struct[=@var{n}] -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
--fno-stack-limit @gol
+-fno-stack-limit -fsplit-stack @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
--fvisibility}
+-fvisibility -fstrict-volatile-bitfields}
@end table
@menu
Free form Fortran source code which must be preprocessed (with the
traditional preprocessor).
+@item @var{file}.go
+Go source code.
+
@c FIXME: Descriptions of Java file types.
@c @var{file}.java
@c @var{file}.class
name suffix). This option applies to all following input files until
the next @option{-x} option. Possible values for @var{language} are:
@smallexample
-c c-header c-cpp-output
+c c-header cpp-output
c++ c++-header c++-cpp-output
objective-c objective-c-header objective-c-cpp-output
objective-c++ objective-c++-header objective-c++-cpp-output
assembler assembler-with-cpp
ada
f77 f77-cpp-input f95 f95-cpp-input
+go
java
@end smallexample
the assembler is unable to read from a pipe; but the GNU assembler has
no trouble.
-@item -combine
-@opindex combine
-If you are compiling multiple source files, this option tells the driver
-to pass all the source files to the compiler at once (for those
-languages for which the compiler can handle this). This will allow
-intermodule analysis (IMA) to be performed by the compiler. Currently the only
-language for which this is supported is C@. If you pass source files for
-multiple languages to the driver, using this option, the driver will invoke
-the compiler(s) that support IMA once each, passing each compiler all the
-source files appropriate for it. For those languages that do not support
-IMA this option will be ignored, and the compiler will be invoked once for
-each source file in that language. If you use this option in conjunction
-with @option{-save-temps}, the compiler will generate multiple
-pre-processed files
-(one for each source file), but only one (combined) @file{.o} or
-@file{.s} file.
-
@item --help
@opindex help
Print (on the standard output) a description of the command line options
@item -wrapper
@opindex wrapper
-Invoke all subcommands under a wrapper program. It takes a single
-comma separated list as an argument, which will be used to invoke
-the wrapper:
+Invoke all subcommands under a wrapper program. The name of the
+wrapper program and its parameters are passed as a comma separated
+list.
@smallexample
gcc -c t.c -wrapper gdb,--args
@end smallexample
-This will invoke all subprograms of gcc under "gdb --args",
-thus cc1 invocation will be "gdb --args cc1 ...".
+This will invoke all subprograms of @command{gcc} under
+@samp{gdb --args}, thus the invocation of @command{cc1} will be
+@samp{gdb --args cc1 @dots{}}.
@item -fplugin=@var{name}.so
Load the plugin code in file @var{name}.so, assumed to be a
specs. @xref{Generating Ada Bindings for C and C++ headers,,, gnat_ugn,
GNAT User's Guide}, which provides detailed documentation on this feature.
+@item -fdump-go-spec=@var{file}
+For input files in any language, generate corresponding Go
+declarations in @var{file}. This generates Go @code{const},
+@code{type}, @code{var}, and @code{func} declarations which may be a
+useful way to start writing a Go interface to code written in some
+other language.
+
@include @value{srcdir}/../libiberty/at-file.texi
@end table
@item -fopenmp
@opindex fopenmp
-@cindex openmp parallel
+@cindex OpenMP parallel
Enable handling of OpenMP directives @code{#pragma omp} in C/C++ and
@code{!$omp} in Fortran. When @option{-fopenmp} is specified, the
compiler generates parallel code according to the OpenMP Application
@opindex fms-extensions
Accept some non-standard constructs used in Microsoft header files.
-It allows for c++ that member-names in structures can be similiar
+In C++ code, this allows member names in structures to be similar
to previous types declarations.
@smallexample
accepted with this option. @xref{Unnamed Fields,,Unnamed struct/union
fields within structs/unions}, for details.
+@item -fplan9-extensions
+Accept some non-standard constructs used in Plan 9 code.
+
+This enables @option{-fms-extensions}, permits passing pointers to
+structures with anonymous fields to functions which expect pointers to
+elements of the type of the field, and permits referring to anonymous
+fields declared using a typedef. @xref{Unnamed Fields,,Unnamed
+struct/union fields within structs/unions}, for details. This is only
+supported for C, not C++.
+
@item -trigraphs
@opindex trigraphs
Support ISO C trigraphs. The @option{-ansi} option (and @option{-std}
Version 4 implements a standard mangling for vector types.
+Version 5 corrects the mangling of attribute const/volatile on
+function pointer types, decltype of a plain decl, and use of a
+function parameter in the declaration of another parameter.
+
See also @option{-Wabi}.
@item -fno-access-control
This option is no longer useful on most targets, now that support has
been added for putting variables into BSS without making them common.
+@item -fconstexpr-depth=@var{n}
+@opindex fconstexpr-depth
+Set the maximum nested evaluation depth for C++0x constexpr functions
+to @var{n}. A limit is needed to detect endless recursion during
+constant expression evaluation. The minimum specified by the standard
+is 512.
+
@item -fno-deduce-init-list
@opindex fno-deduce-init-list
Disable deduction of a template type parameter as
@item -Woverloaded-virtual @r{(C++ and Objective-C++ only)}
@opindex Woverloaded-virtual
@opindex Wno-overloaded-virtual
-@cindex overloaded virtual fn, warning
-@cindex warning for overloaded virtual fn
+@cindex overloaded virtual function, warning
+@cindex warning for overloaded virtual function
Warn when a function declaration hides virtual functions from a
base class. For example, in:
@cindex Objective-C and Objective-C++ options, command line
@cindex options, Objective-C and Objective-C++
(NOTE: This manual does not describe the Objective-C and Objective-C++
-languages themselves. See @xref{Standards,,Language Standards
+languages themselves. @xref{Standards,,Language Standards
Supported by GCC}, for references.)
This section describes the command-line options that are only meaningful
@item -fno-nil-receivers
@opindex fno-nil-receivers
-Assume that all Objective-C message dispatches (e.g.,
-@code{[receiver message:arg]}) in this translation unit ensure that the receiver
-is not @code{nil}. This allows for more efficient entry points in the runtime
-to be used. Currently, this option is only available in conjunction with
-the NeXT runtime on Mac OS X 10.3 and later.
+Assume that all Objective-C message dispatches (@code{[receiver
+message:arg]}) in this translation unit ensure that the receiver is
+not @code{nil}. This allows for more efficient entry points in the
+runtime to be used. This option is only available in conjunction with
+the NeXT runtime and ABI version 0 or 1.
+
+@item -fobjc-abi-version=@var{n}
+@opindex fobjc-abi-version
+Use version @var{n} of the Objective-C ABI for the selected runtime.
+This option is currently supported only for the NeXT runtime. In that
+case, Version 0 is the traditional (32-bit) ABI without support for
+properties and other Objective-C 2.0 additions. Version 1 is the
+traditional (32-bit) ABI with support for properties and other
+Objective-C 2.0 additions. Version 2 is the modern (64-bit) ABI. If
+nothing is specified, the default is Version 0 on 32-bit target
+machines, and Version 2 on 64-bit target machines.
@item -fobjc-call-cxx-cdtors
@opindex fobjc-call-cxx-cdtors
special @code{- (void) .cxx_destruct} method that will run
all such default destructors, in reverse order.
-The @code{- (id) .cxx_construct} and/or @code{- (void) .cxx_destruct} methods
-thusly generated will only operate on instance variables declared in the
-current Objective-C class, and not those inherited from superclasses. It
-is the responsibility of the Objective-C runtime to invoke all such methods
-in an object's inheritance hierarchy. The @code{- (id) .cxx_construct} methods
-will be invoked by the runtime immediately after a new object
-instance is allocated; the @code{- (void) .cxx_destruct} methods will
-be invoked immediately before the runtime deallocates an object instance.
+The @code{- (id) .cxx_construct} and @code{- (void) .cxx_destruct}
+methods thusly generated will only operate on instance variables
+declared in the current Objective-C class, and not those inherited
+from superclasses. It is the responsibility of the Objective-C
+runtime to invoke all such methods in an object's inheritance
+hierarchy. The @code{- (id) .cxx_construct} methods will be invoked
+by the runtime immediately after a new object instance is allocated;
+the @code{- (void) .cxx_destruct} methods will be invoked immediately
+before the runtime deallocates an object instance.
As of this writing, only the NeXT runtime on Mac OS X 10.4 and later has
support for invoking the @code{- (id) .cxx_construct} and
@item -fobjc-exceptions
@opindex fobjc-exceptions
-Enable syntactic support for structured exception handling in Objective-C,
-similar to what is offered by C++ and Java. This option is
-unavailable in conjunction with the NeXT runtime on Mac OS X 10.2 and
-earlier.
-
-@smallexample
- @@try @{
- @dots{}
- @@throw expr;
- @dots{}
- @}
- @@catch (AnObjCClass *exc) @{
- @dots{}
- @@throw expr;
- @dots{}
- @@throw;
- @dots{}
- @}
- @@catch (AnotherClass *exc) @{
- @dots{}
- @}
- @@catch (id allOthers) @{
- @dots{}
- @}
- @@finally @{
- @dots{}
- @@throw expr;
- @dots{}
- @}
-@end smallexample
-
-The @code{@@throw} statement may appear anywhere in an Objective-C or
-Objective-C++ program; when used inside of a @code{@@catch} block, the
-@code{@@throw} may appear without an argument (as shown above), in which case
-the object caught by the @code{@@catch} will be rethrown.
-
-Note that only (pointers to) Objective-C objects may be thrown and
-caught using this scheme. When an object is thrown, it will be caught
-by the nearest @code{@@catch} clause capable of handling objects of that type,
-analogously to how @code{catch} blocks work in C++ and Java. A
-@code{@@catch(id @dots{})} clause (as shown above) may also be provided to catch
-any and all Objective-C exceptions not caught by previous @code{@@catch}
-clauses (if any).
-
-The @code{@@finally} clause, if present, will be executed upon exit from the
-immediately preceding @code{@@try @dots{} @@catch} section. This will happen
-regardless of whether any exceptions are thrown, caught or rethrown
-inside the @code{@@try @dots{} @@catch} section, analogously to the behavior
-of the @code{finally} clause in Java.
-
-There are several caveats to using the new exception mechanism:
-
-@itemize @bullet
-@item
-Although currently designed to be binary compatible with @code{NS_HANDLER}-style
-idioms provided by the @code{NSException} class, the new
-exceptions can only be used on Mac OS X 10.3 (Panther) and later
-systems, due to additional functionality needed in the (NeXT) Objective-C
-runtime.
-
-@item
-As mentioned above, the new exceptions do not support handling
-types other than Objective-C objects. Furthermore, when used from
-Objective-C++, the Objective-C exception model does not interoperate with C++
-exceptions at this time. This means you cannot @code{@@throw} an exception
-from Objective-C and @code{catch} it in C++, or vice versa
-(i.e., @code{throw @dots{} @@catch}).
-@end itemize
-
-The @option{-fobjc-exceptions} switch also enables the use of synchronization
-blocks for thread-safe execution:
-
-@smallexample
- @@synchronized (ObjCClass *guard) @{
- @dots{}
- @}
-@end smallexample
-
-Upon entering the @code{@@synchronized} block, a thread of execution shall
-first check whether a lock has been placed on the corresponding @code{guard}
-object by another thread. If it has, the current thread shall wait until
-the other thread relinquishes its lock. Once @code{guard} becomes available,
-the current thread will place its own lock on it, execute the code contained in
-the @code{@@synchronized} block, and finally relinquish the lock (thereby
-making @code{guard} available to other threads).
-
-Unlike Java, Objective-C does not allow for entire methods to be marked
-@code{@@synchronized}. Note that throwing exceptions out of
-@code{@@synchronized} blocks is allowed, and will cause the guarding object
-to be unlocked properly.
+Enable syntactic support for structured exception handling in
+Objective-C, similar to what is offered by C++ and Java. This option
+is required to use the Objective-C keywords @code{@@try},
+@code{@@throw}, @code{@@catch}, @code{@@finally} and
+@code{@@synchronized}. This option is available with both the GNU
+runtime and the NeXT runtime (but not available in conjunction with
+the NeXT runtime on Mac OS X 10.2 and earlier).
@item -fobjc-gc
@opindex fobjc-gc
-Enable garbage collection (GC) in Objective-C and Objective-C++ programs.
+Enable garbage collection (GC) in Objective-C and Objective-C++
+programs. This option is only available with the NeXT runtime; the
+GNU runtime has a different garbage collection implementation that
+does not require special compiler flags.
+
+@item -fobjc-nilcheck
+@opindex fobjc-nilcheck
+For the NeXT runtime with version 2 of the ABI, check for a nil
+receiver in method invocations before doing the actual method call.
+This is the default and can be disabled using
+@option{-fno-objc-nilcheck}. Class methods and super calls are never
+checked for nil in this way no matter what this flag is set to.
+Currently this flag does nothing when the GNU runtime, or an older
+version of the NeXT runtime ABI, is used.
+
+@item -fobjc-std=objc1
+@opindex fobjc-std
+Conform to the language syntax of Objective-C 1.0, the language
+recognized by GCC 4.0. This only affects the Objective-C additions to
+the C/C++ language; it does not affect conformance to C/C++ standards,
+which is controlled by the separate C/C++ dialect option flags. When
+this option is used with the Objective-C or Objective-C++ compiler,
+any Objective-C syntax that is not recognized by GCC 4.0 is rejected.
+This is useful if you need to make sure that your Objective-C code can
+be compiled with older versions of GCC.
@item -freplace-objc-classes
@opindex freplace-objc-classes
suppresses this behavior and causes calls to @code{objc_getClass("@dots{}")}
to be retained. This is useful in Zero-Link debugging mode, since it allows
for individual class implementations to be modified during program execution.
+The GNU runtime currently always retains calls to @code{objc_get_class("@dots{}")}
+regardless of command line options.
@item -gen-decls
@opindex gen-decls
prefix) for physical lines that result from the process of breaking
a message which is too long to fit on a single line.
-@item -fdiagnostics-show-option
+@item -fno-diagnostics-show-option
+@opindex fno-diagnostics-show-option
@opindex fdiagnostics-show-option
-This option instructs the diagnostic machinery to add text to each
-diagnostic emitted, which indicates which command line option directly
-controls that diagnostic, when such an option is known to the
-diagnostic machinery.
+By default, each diagnostic emitted includes text which indicates the
+command line option that directly controls the diagnostic (if such an
+option is known to the diagnostic machinery). Specifying the
+@option{-fno-diagnostics-show-option} flag suppresses that behavior.
@item -Wcoverage-mismatch
@opindex Wcoverage-mismatch
@opindex fsyntax-only
Check the code for syntax errors, but don't do anything beyond that.
+@item -fmax-errors=@var{n}
+@opindex fmax-errors
+Limits the maximum number of error messages to @var{n}, at which point
+GCC bails out rather than attempting to continue processing the source
+code. If @var{n} is 0 (the default), there is no limit on the number
+of error messages produced. If @option{-Wfatal-errors} is also
+specified, then @option{-Wfatal-errors} takes precedence over this
+option.
+
@item -w
@opindex w
Inhibit all warning messages.
negative form, to be used to negate @option{-Werror} for specific
warnings, for example @option{-Wno-error=switch} makes
@option{-Wswitch} warnings not be errors, even when @option{-Werror}
-is in effect. You can use the @option{-fdiagnostics-show-option}
-option to have each controllable warning amended with the option which
-controls it, to determine what to use with this option.
+is in effect.
+
+The warning message for each controllable warning includes the
+option which controls the warning. That option can then be used with
+@option{-Werror=} and @option{-Wno-error=} as described above.
+(Printing of the option in the warning message can be disabled using the
+@option{-fno-diagnostics-show-option} flag.)
Note that specifying @option{-Werror=}@var{foo} automatically implies
@option{-W}@var{foo}. However, @option{-Wno-error=}@var{foo} does not
Suppress warning messages emitted by @code{#warning} directives.
+@item -Wdouble-promotion @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wdouble-promotion
+@opindex Wno-double-promotion
+Give a warning when a value of type @code{float} is implicitly
+promoted to @code{double}. CPUs with a 32-bit ``single-precision''
+floating-point unit implement @code{float} in hardware, but emulate
+@code{double} in software. On such a machine, doing computations
+using @code{double} values is much more expensive because of the
+overhead required for software emulation.
+
+It is easy to accidentally do computations with @code{double} because
+floating-point literals are implicitly of type @code{double}. For
+example, in:
+@smallexample
+@group
+float area(float radius)
+@{
+ return 3.14159 * radius * radius;
+@}
+@end group
+@end smallexample
+the compiler will perform the entire computation with @code{double}
+because the floating-point literal is a @code{double}.
+
@item -Wformat
@opindex Wformat
@opindex Wno-format
over the precise meaning of the sequence point rules in subtle cases.
Links to discussions of the problem, including proposed formal
definitions, may be found on the GCC readings page, at
-@w{@uref{http://gcc.gnu.org/readings.html}}.
+@uref{http://gcc.gnu.org/@/readings.html}.
This warning is enabled by @option{-Wall} for C and C++.
@option{-femit-struct-debug-reduced} and @option{-femit-struct-debug-baseonly},
which will serve for most needs.
-A specification has the syntax
+A specification has the syntax@*
[@samp{dir:}|@samp{ind:}][@samp{ord:}|@samp{gen:}](@samp{any}|@samp{sys}|@samp{base}|@samp{none})
The optional first word limits the specification to
This option works only with DWARF 2.
-@item -fenable-icf-debug
-@opindex fenable-icf-debug
-Generate additional debug information to support identical code folding (ICF).
-This option only works with DWARF version 2 or higher.
-
@item -fno-merge-debug-strings
@opindex fmerge-debug-strings
@opindex fno-merge-debug-strings
Makes the compiler print some statistics about permanent memory
allocation before or after interprocedural optimization.
+@item -fstack-usage
+@opindex fstack-usage
+Makes the compiler output stack usage information for the program, on a
+per-function basis. The filename for the dump is made by appending
+@file{.su} to the @var{auxname}. @var{auxname} 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. An entry is made up
+of three fields:
+
+@itemize
+@item
+The name of the function.
+@item
+A number of bytes.
+@item
+One or more qualifiers: @code{static}, @code{dynamic}, @code{bounded}.
+@end itemize
+
+The qualifier @code{static} means that the function manipulates the stack
+statically: a fixed number of bytes are allocated for the frame on function
+entry and released on function exit; no stack adjustments are otherwise made
+in the function. The second field is this fixed number of bytes.
+
+The qualifier @code{dynamic} means that the function manipulates the stack
+dynamically: in addition to the static allocation described above, stack
+adjustments are made in the body of the function, for example to push/pop
+arguments around function calls. If the qualifier @code{bounded} is also
+present, the amount of these adjustments is bounded at compile-time and
+the second field is an upper bound of the total amount of stack used by
+the function. If it is not present, the amount of these adjustments is
+not bounded at compile-time and the second field only represents the
+bounded part.
+
@item -fprofile-arcs
@opindex fprofile-arcs
Add code so that program flow @dfn{arcs} are instrumented. During
@item -fdbg-cnt-list
@opindex fdbg-cnt-list
-Print the name and the counter upperbound for all debug counters.
+Print the name and the counter upper bound for all debug counters.
@item -fdbg-cnt=@var{counter-value-list}
@opindex fdbg-cnt
-Set the internal debug counter upperbound. @var{counter-value-list}
+Set the internal debug counter upper bound. @var{counter-value-list}
is a comma-separated list of @var{name}:@var{value} pairs
-which sets the upperbound of each debug counter @var{name} to @var{value}.
-All debug counters have the initial upperbound of @var{UINT_MAX},
-thus dbg_cnt() returns true always unless the upperbound is set by this option.
+which sets the upper bound of each debug counter @var{name} to @var{value}.
+All debug counters have the initial upper bound of @var{UINT_MAX},
+thus dbg_cnt() returns true always unless the upper bound is set by this option.
e.g. With -fdbg-cnt=dce:10,tail_call:0
dbg_cnt(dce) will return true only for first 10 invocations
and dbg_cnt(tail_call) will return false always.
@var{letters}. This is used for debugging the RTL-based passes of the
compiler. The file names for most of the dumps are made by appending
a pass number and a word to the @var{dumpname}, and the files are
-created in the directory of the output file. @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. These switches may have different effects when
-@option{-E} is used for preprocessing.
+created in the directory of the output file. Note that the pass
+number is computed statically as passes get registered into the pass
+manager. Thus the numbering is not related to the dynamic order of
+execution of passes. In particular, a pass installed by a plugin
+could have a number over 200 even if it executed quite early.
+@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. These switches may have different effects
+when @option{-E} is used for preprocessing.
Debug dumps can be enabled with a @option{-fdump-rtl} switch or some
@option{-d} option @var{letters}. Here are the possible
@opindex dx
Just generate RTL for a function instead of compiling it. Usually used
with @option{-fdump-rtl-expand}.
-
-@item -dy
-@opindex dy
-Dump debugging information during parsing, to standard error.
@end table
@item -fdump-noaddr
@option{-O} turns on the following optimization flags:
@gccoptlist{
-fauto-inc-dec @gol
+-fcompare-elim @gol
-fcprop-registers @gol
-fdce @gol
-fdefer-pop @gol
-fcrossjumping @gol
-fcse-follow-jumps -fcse-skip-blocks @gol
-fdelete-null-pointer-checks @gol
+-fdevirtualize @gol
-fexpensive-optimizations @gol
-fgcse -fgcse-lm @gol
-finline-small-functions @gol
Optimize yet more. @option{-O3} turns on all optimizations specified
by @option{-O2} and also turns on the @option{-finline-functions},
@option{-funswitch-loops}, @option{-fpredictive-commoning},
-@option{-fgcse-after-reload} and @option{-ftree-vectorize} options.
+@option{-fgcse-after-reload}, @option{-ftree-vectorize} and
+@option{-fipa-cp-clone} options.
@item -O0
@opindex O0
This option is enabled by default at optimization levels @option{-O},
@option{-O2}, @option{-O3}, @option{-Os}.
+@item -ffp-contract=@var{style}
+@opindex ffp-contract
+@option{-ffp-contract=off} disables floating-point expression contraction.
+@option{-ffp-contract=fast} enables floating-point expression contraction
+such as forming of fused multiply-add operations if the target has
+native support for them.
+@option{-ffp-contract=on} enables floating-point expression contraction
+if allowed by the language standard. This is currently not implemented
+and treated equal to @option{-ffp-contract=off}.
+
+The default is @option{-ffp-contract=fast}.
+
@item -fomit-frame-pointer
@opindex fomit-frame-pointer
Don't keep the frame pointer in a register for functions that
of assembly instructions and as such its exact meaning might change from one
release to an another.
+@item -fno-keep-inline-dllexport
+@opindex -fno-keep-inline-dllexport
+This is a more fine-grained version of @option{-fkeep-inline-functions},
+which applies only to functions that are declared using the @code{dllexport}
+attribute or declspec (@xref{Function Attributes,,Declaring Attributes of
+Functions}.)
+
@item -fkeep-inline-functions
@opindex fkeep-inline-functions
In C, emit @code{static} functions that are declared @code{inline}
@option{-O2}, @option{-O3}, @option{-Os}. Passes that use the information
are enabled independently at different optimization levels.
+@item -fdevirtualize
+@opindex fdevirtualize
+Attempt to convert calls to virtual functions to direct calls. This
+is done both within a procedure and interprocedurally as part of
+indirect inlining (@code{-findirect-inlining}) and interprocedural constant
+propagation (@option{-fipa-cp}).
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
@item -fexpensive-optimizations
@opindex fexpensive-optimizations
Perform a number of minor optimizations that are relatively expensive.
decent code and the smallest size code, and the default value usually
give the best results in most cases and for most architectures.
-@item -fira-coalesce
-@opindex fira-coalesce
-Do optimistic register coalescing. This option might be profitable for
-architectures with big regular register files.
-
@item -fira-loop-pressure
@opindex fira-loop-pressure
Use IRA to evaluate register pressure in loops for decision to move
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fcombine-stack-adjustments
+@opindex fcombine-stack-adjustments
+Tracks stack adjustments (pushes and pops) and stack memory references
+and then tries to find ways to combine them.
+
+Enabled by default at @option{-O1} and higher.
+
@item -fconserve-stack
@opindex fconserve-stack
Attempt to minimize stack usage. The compiler will attempt to use less
affective for programs containing arrays of structures. Available in two
compilation modes: profile-based (enabled with @option{-fprofile-generate})
or static (which uses built-in heuristics). It works only in whole program
-mode, so it requires @option{-fwhole-program} and @option{-combine} to be
+mode, so it requires @option{-fwhole-program} to be
enabled. Structures considered @samp{cold} by this transformation are not
affected (see @option{--param struct-reorg-cold-struct-ratio=@var{value}}).
@item -ftree-loop-linear
@opindex ftree-loop-linear
-Perform linear loop transformations on tree. This flag can improve cache
-performance and allow further loop optimizations to take place.
+Perform loop interchange transformations on tree. Same as
+@option{-floop-interchange}. To use this code transformation, GCC has
+to be configured with @option{--with-ppl} and @option{--with-cloog} to
+enable the Graphite loop transformation infrastructure.
@item -floop-interchange
+@opindex floop-interchange
Perform loop interchange transformations on loops. Interchanging two
nested loops switches the inner and outer loops. For example, given a
loop like:
Graphite loop transformation infrastructure.
@item -floop-strip-mine
+@opindex floop-strip-mine
Perform loop strip mining transformations on loops. Strip mining
splits a loop into two nested loops. The outer loop has strides
equal to the strip size and the inner loop has strides of the
enable the Graphite loop transformation infrastructure.
@item -floop-block
+@opindex floop-block
Perform loop blocking transformations on loops. Blocking strip mines
each loop in the loop nest such that the memory accesses of the
element loops fit inside caches. The strip length can be changed
are also performed by the code generator CLooG, like index splitting and
dead code elimination in loops.
+@item -floop-flatten
+@opindex floop-flatten
+Removes the loop nesting structure: transforms the loop nest into a
+single loop. This transformation can be useful to vectorize all the
+levels of the loop nest.
+
@item -floop-parallelize-all
+@opindex floop-parallelize-all
Use the Graphite data dependence analysis to identify loops that can
be parallelized. Parallelize all the loops that can be analyzed to
not contain loop carried dependences without checking that it is
vectorization pass to handle these loops. This is enabled by default
if vectorization is enabled.
+@item -ftree-loop-if-convert-stores
+Attempt to also if-convert conditional jumps containing memory writes.
+This transformation can be unsafe for multi-threaded programs as it
+transforms conditional memory writes into unconditional memory writes.
+For example,
+@smallexample
+for (i = 0; i < N; i++)
+ if (cond)
+ A[i] = expr;
+@end smallexample
+would be transformed to
+@smallexample
+for (i = 0; i < N; i++)
+ A[i] = cond ? expr : A[i];
+@end smallexample
+potentially producing data races.
+
@item -ftree-loop-distribution
Perform loop distribution. This flag can improve cache performance on
big loop bodies and allow further loop optimizations, like
and in effect are optimized more aggressively by interprocedural optimizers. If @command{gold} is used as the linker plugin, @code{externally_visible} attributes are automatically added to functions (not variable yet due to a current @command{gold} issue) that are accessed outside of LTO objects according to resolution file produced by @command{gold}. For other linkers that cannot generate resolution file, explicit @code{externally_visible} attributes are still necessary.
While this option is equivalent to proper use of the @code{static} keyword for
programs consisting of a single file, in combination with option
-@option{-combine}, @option{-flto} or @option{-fwhopr} this flag can be used to
+@option{-flto} this flag can be used to
compile many smaller scale programs since the functions and variables become
local for the whole combined compilation unit, not for the single source file
itself.
This option implies @option{-fwhole-file} for Fortran programs.
-@item -flto
+@item -flto[=@var{n}]
@opindex flto
This option runs the standard link-time optimizer. When invoked
with source code, it generates GIMPLE (one of GCC's internal
optimizations the @option{-flto} flag needs to be passed to both the
compile and the link commands.
+To make whole program optimization effective, it is necessary to make
+certain whole program assumptions. The compiler needs to know
+what functions and variables can be accessed by libraries and runtime
+outside of the link time optimized unit. When supported by the linker,
+the linker plugin (see @option{-fuse-linker-plugin}) passes to the
+compiler information about used and externally visible symbols. When
+the linker plugin is not available, @option{-fwhole-program} should be
+used to allow the compiler to make these assumptions, which will lead
+to more aggressive optimization decisions.
+
Note that when a file is compiled with @option{-flto}, the generated
object file will be larger than a regular object file because it will
contain GIMPLE bytecodes and the usual final code. This means that
behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
issued. The behavior is still undefined at runtime.
-If object files containing GIMPLE bytecode are stored in a library
-archive, say @file{libfoo.a}, it is possible to extract and use them
-in an LTO link if you are using @command{gold} as the linker (which,
-in turn requires GCC to be configured with @option{--enable-gold}).
-To enable this feature, use the flag @option{-fuse-linker-plugin} at
-link-time:
+If object files containing GIMPLE bytecode are stored in a library archive, say
+@file{libfoo.a}, it is possible to extract and use them in an LTO link if you
+are using a linker with linker plugin support. To enable this feature, use
+the flag @option{-fuse-linker-plugin} at link-time:
@smallexample
gcc -o myprog -O2 -flto -fuse-linker-plugin a.o b.o -lfoo
@end smallexample
-With the linker plugin enabled, @command{gold} will extract the needed
+With the linker plugin enabled, the linker will extract the needed
GIMPLE files from @file{libfoo.a} and pass them on to the running GCC
to make them part of the aggregated GIMPLE image to be optimized.
-If you are not using @command{gold} and/or do not specify
-@option{-fuse-linker-plugin} then the objects inside @file{libfoo.a}
+If you are not using a linker with linker plugin support and/or do not
+enable linker plugin then the objects inside @file{libfoo.a}
will be extracted and linked as usual, but they will not participate
in the LTO optimization process.
-Link time optimizations do not require the presence of the whole
-program to operate. If the program does not require any symbols to
-be exported, it is possible to combine @option{-flto} and
-@option{-fwhopr} with @option{-fwhole-program} to allow the
-interprocedural optimizers to use more aggressive assumptions which
-may lead to improved optimization opportunities.
+Link time optimizations do not require the presence of the whole program to
+operate. If the program does not require any symbols to be exported, it is
+possible to combine @option{-flto} and with @option{-fwhole-program} to allow
+the interprocedural optimizers to use more aggressive assumptions which may
+lead to improved optimization opportunities.
+Use of @option{-fwhole-program} is not needed when linker plugin is
+active (see @option{-fuse-linker-plugin}).
Regarding portability: the current implementation of LTO makes no
attempt at generating bytecode that can be ported between different
GCC will not work with an older/newer version of GCC.
Link time optimization does not play well with generating debugging
-information. Combining @option{-flto} or @option{-fwhopr} with
-@option{-g} is experimental.
+information. Combining @option{-flto} with
+@option{-g} is currently experimental and expected to produce wrong
+results.
+
+If you specify the optional @var{n}, the optimization and code
+generation done at link time is executed in parallel using @var{n}
+parallel jobs by utilizing an installed @command{make} program. The
+environment variable @env{MAKE} may be used to override the program
+used. The default value for @var{n} is 1.
+
+You can also specify @option{-flto=jobserver} to use GNU make's
+job server mode to determine the number of parallel jobs. This
+is useful when the Makefile calling GCC is already executing in parallel.
+The parent Makefile will need a @samp{+} prepended to the command recipe
+for this to work. This will likely only work if @env{MAKE} is
+GNU make.
This option is disabled by default.
-@item -fwhopr[=@var{n}]
-@opindex fwhopr
-This option is identical in functionality to @option{-flto} but it
-differs in how the final link stage is executed. Instead of loading
-all the function bodies in memory, the callgraph is analyzed and
-optimization decisions are made (whole program analysis or WPA). Once
-optimization decisions are made, the callgraph is partitioned and the
-different sections are compiled separately (local transformations or
-LTRANS)@. This process allows optimizations on very large programs
-that otherwise would not fit in memory. This option enables
-@option{-fwpa} and @option{-fltrans} automatically.
-
-If you specify the optional @var{n} the link stage is executed in
-parallel using @var{n} parallel jobs by utilizing an installed
-@command{make} program. The environment variable @env{MAKE} may be
-used to override the program used.
-
-Disabled by default.
-
-@item -fwpa
-@opindex fwpa
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option runs the link-time optimizer in the whole-program-analysis
-(WPA) mode, which reads in summary information from all inputs and
-performs a whole-program analysis based on summary information only.
-It generates object files for subsequent runs of the link-time
-optimizer where individual object files are optimized using both
-summary information from the WPA mode and the actual function bodies.
-It then drives the LTRANS phase.
-
-Disabled by default.
-
-@item -fltrans
-@opindex fltrans
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option runs the link-time optimizer in the local-transformation (LTRANS)
-mode, which reads in output from a previous run of the LTO in WPA mode.
-In the LTRANS mode, LTO optimizes an object and produces the final assembly.
-
-Disabled by default.
-
-@item -fltrans-output-list=@var{file}
-@opindex fltrans-output-list
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option specifies a file to which the names of LTRANS output files are
-written. This option is only meaningful in conjunction with @option{-fwpa}.
-
-Disabled by default.
+@item -flto-partition=@var{alg}
+@opindex flto-partition
+Specify the partitioning algorithm used by the link time optimizer.
+The value is either @code{1to1} to specify a partitioning mirroring
+the original source files or @code{balanced} to specify partitioning
+into equally sized chunks (whenever possible). Specifying @code{none}
+as an algorithm disables partitioning and streaming completely. The
+default value is @code{balanced}.
@item -flto-compression-level=@var{n}
This option specifies the level of compression used for intermediate
language written to LTO object files, and is only meaningful in
-conjunction with LTO mode (@option{-fwhopr}, @option{-flto}). Valid
+conjunction with LTO mode (@option{-flto}). Valid
values are 0 (no compression) to 9 (maximum compression). Values
outside this range are clamped to either 0 or 9. If the option is not
given, a default balanced compression setting is used.
Prints a report with internal details on the workings of the link-time
optimizer. The contents of this report vary from version to version,
it is meant to be useful to GCC developers when processing object
-files in LTO mode (via @option{-fwhopr} or @option{-flto}).
+files in LTO mode (via @option{-flto}).
Disabled by default.
@item -fuse-linker-plugin
-Enables the extraction of objects with GIMPLE bytecode information
-from library archives. This option relies on features available only
-in @command{gold}, so to use this you must configure GCC with
-@option{--enable-gold}. See @option{-flto} for a description on the
-effect of this flag and how to use it.
+Enables the use of linker plugin during link time optimization. This option
+relies on the linker plugin support in linker that is available in gold
+or in GNU ld 2.21 or newer.
+
+This option enables the extraction of object files with GIMPLE bytecode out of
+library archives. This improves the quality of optimization by exposing more
+code the the link time optimizer. This information specify what symbols
+can be accessed externally (by non-LTO object or during dynamic linking).
+Resulting code quality improvements on binaries (and shared libraries that do
+use hidden visibility) is similar to @code{-fwhole-program}. See
+@option{-flto} for a description on the effect of this flag and how to use it.
+
+Enabled by default when LTO support in GCC is enabled and GCC was compiled
+with a linker supporting plugins (GNU ld 2.21 or newer or gold).
+
+@item -fcompare-elim
+@opindex fcompare-elim
+After register allocation and post-register allocation instruction splitting,
+identify arithmetic instructions that compute processor flags similar to a
+comparison operation based on that arithmetic. If possible, eliminate the
+explicit comparison operation.
-Disabled by default.
+This pass only applies to certain targets that cannot explicitly represent
+the comparison operation before register allocation is complete.
+
+Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fcprop-registers
@opindex fcprop-registers
@item -fprofile-dir=@var{path}
@opindex fprofile-dir
-Set the directory to search the profile data files in to @var{path}.
+Set the directory to search for the profile data files in to @var{path}.
This option affects only the profile data generated by
@option{-fprofile-generate}, @option{-ftest-coverage}, @option{-fprofile-arcs}
and used by @option{-fprofile-use} and @option{-fbranch-probabilities}
and its related options.
-By default, GCC will use the current directory as @var{path}
-thus the profile data file will appear in the same directory as the object file.
+By default, GCC will use the current directory as @var{path}, thus the
+profile data file will appear in the same directory as the object file.
@item -fprofile-generate
@itemx -fprofile-generate=@var{path}
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
-This option is not turned on by any @option{-O} option since
-it can result in incorrect output for programs which depend on
-an exact implementation of IEEE or ISO rules/specifications for
-math functions. It may, however, yield faster code for programs
+This option is not turned on by any @option{-O} option besides
+@option{-Ofast} since it can result in incorrect output for programs
+which depend on an exact implementation of IEEE or ISO rules/specifications
+for math functions. It may, however, yield faster code for programs
that do not require the guarantees of these specifications.
@item -fno-math-errno
@samp{REG_BR_PROB} note on each @samp{JUMP_INSN} and @samp{CALL_INSN}.
These can be used to improve optimization. Currently, they are only
used in one place: in @file{reorg.c}, instead of guessing which path a
-branch is mostly to take, the @samp{REG_BR_PROB} values are used to
+branch is most likely to take, the @samp{REG_BR_PROB} values are used to
exactly determine which path is taken more often.
@item -fprofile-values
data about values of expressions in the program is gathered.
With @option{-fbranch-probabilities}, it reads back the data gathered
-from profiling values of expressions and adds @samp{REG_VALUE_PROFILE}
-notes to instructions for their later usage in optimizations.
+from profiling values of expressions for usage in optimizations.
Enabled with @option{-fprofile-generate} and @option{-fprofile-use}.
optimization. If more memory than specified is required, the
optimization will not be done.
+@item max-gcse-insertion-ratio
+If the ratio of expression insertions to deletions is larger than this value
+for any expression, then RTL PRE will insert or remove the expression and thus
+leave partially redundant computations in the instruction stream. The default value is 20.
+
@item max-pending-list-length
The maximum number of pending dependencies scheduling will allow
before flushing the current state and starting over. Large functions
internal representation) in a single function that the tree inliner
will consider for inlining. This only affects functions declared
inline and methods implemented in a class declaration (C++).
-The default value is 300.
+The default value is 400.
@item max-inline-insns-auto
When you use @option{-finline-functions} (included in @option{-O3}),
@item early-inlining-insns
Specify growth that early inliner can make. In effect it increases amount of
-inlining for code having large abstraction penalty. The default value is 8.
+inlining for code having large abstraction penalty. The default value is 10.
@item max-early-inliner-iterations
@itemx max-early-inliner-iterations
indirect calls early inliner can resolve. Deeper chains are still handled by
late inlining.
+@item comdat-sharing-probability
+@itemx comdat-sharing-probability
+Probability (in percent) that C++ inline function with comdat visibility
+will be shared across multiple compilation units. The default value is 20.
+
@item min-vect-loop-bound
The minimum number of iterations under which a loop will not get vectorized
when @option{-ftree-vectorize} is used. The number of iterations after
@item gcse-cost-distance-ratio
Scaling factor in calculation of maximum distance an expression
-can be moved by GCSE optimizations. This is currently supported only in
-code hoisting pass. The bigger the ratio, the more agressive code hoisting
+can be moved by GCSE optimizations. This is currently supported only in the
+code hoisting pass. The bigger the ratio, the more aggressive code hoisting
will be with simple expressions, i.e., the expressions which have cost
less than @option{gcse-unrestricted-cost}. Specifying 0 will disable
hoisting of simple expressions. The default value is 10.
Cost, roughly measured as the cost of a single typical machine
instruction, at which GCSE optimizations will not constrain
the distance an expression can travel. This is currently
-supported only in code hoisting pass. The lesser the cost,
+supported only in the code hoisting pass. The lesser the cost,
the more aggressive code hoisting will be. Specifying 0 will
allow all expressions to travel unrestricted distances.
The default value is 3.
Bound on size of expressions used in the scalar evolutions analyzer.
Large expressions slow the analyzer.
+@item scev-max-expr-complexity
+Bound on the complexity of the expressions in the scalar evolutions analyzer.
+Complex expressions slow the analyzer.
+
@item omega-max-vars
The maximum number of variables in an Omega constraint system.
The default value is 128.
given basic block needs to have to be considered hot.
@item hot-bb-frequency-fraction
-Select fraction of the maximal frequency of executions of basic block in
+Select fraction of the entry block frequency of executions of basic block in
function given basic block needs to have to be considered hot
@item max-predicted-iterations
@option{devirt-type-list-size} is the maximum number of types it
stores per a single formal parameter of a function.
+@item lto-partitions
+Specify desired number of partitions produced during WHOPR compilation.
+The number of partitions should exceed the number of CPUs used for compilation.
+The default value is 32.
+
+@item lto-minpartition
+Size of minimal partition for WHOPR (in estimated instructions).
+This prevents expenses of splitting very small programs into too many
+partitions.
+
+@item cxx-max-namespaces-for-diagnostic-help
+The maximum number of namespaces to consult for suggestions when C++
+name lookup fails for an identifier. The default is 1000.
+
@end table
@end table
@table @code
@item %include <@var{file}>
-@cindex %include
+@cindex @code{%include}
Search for @var{file} and insert its text at the current point in the
specs file.
@item %include_noerr <@var{file}>
-@cindex %include_noerr
+@cindex @code{%include_noerr}
Just like @samp{%include}, but do not generate an error message if the include
file cannot be found.
@item %rename @var{old_name} @var{new_name}
-@cindex %rename
+@cindex @code{%rename}
Rename the spec string @var{old_name} to @var{new_name}.
@end table
%:remove-outfile(-lm)
@end smallexample
+@item @code{pass-through-libs}
+The @code{pass-through-libs} spec function takes any number of arguments. It
+finds any @option{-l} options and any non-options ending in ".a" (which it
+assumes are the names of linker input library archive files) and returns a
+result containing all the found arguments each prepended by
+@option{-plugin-opt=-pass-through=} and joined by spaces. This list is
+intended to be passed to the LTO linker plugin.
+
+@smallexample
+%:pass-through-libs(%G %L %G)
+@end smallexample
+
@item @code{print-asm-header}
The @code{print-asm-header} function takes no arguments and simply
prints a banner like:
@cindex compiler version, specifying
@cindex target machine, specifying
-The usual way to run GCC is to run the executable called @file{gcc}, or
-@file{<machine>-gcc} when cross-compiling, or
-@file{<machine>-gcc-<version>} to run a version other than the one that
-was installed last.
+The usual way to run GCC is to run the executable called @command{gcc}, or
+@command{@var{machine}-gcc} when cross-compiling, or
+@command{@var{machine}-gcc-@var{version}} to run a version other than the
+one that was installed last.
@node Submodel Options
@section Hardware Models and Configurations
* M68hc1x Options::
* MCore Options::
* MeP Options::
+* MicroBlaze Options::
* MIPS Options::
* MMIX Options::
* MN10300 Options::
* S/390 and zSeries Options::
* Score Options::
* SH Options::
+* Solaris 2 Options::
* SPARC Options::
* SPU Options::
* System V Options::
@item -mmangle-cpu
@opindex mmangle-cpu
-Prepend the name of the cpu to all public symbol names.
+Prepend the name of the CPU to all public symbol names.
In multiple-processor systems, there are many ARC variants with different
instruction and register set characteristics. This flag prevents code
-compiled for one cpu to be linked with code compiled for another.
+compiled for one CPU to be linked with code compiled for another.
No facility exists for handling variants that are ``almost identical''.
This is an all or nothing option.
@samp{arm10e}, @samp{arm1020e}, @samp{arm1022e},
@samp{arm1136j-s}, @samp{arm1136jf-s}, @samp{mpcore}, @samp{mpcorenovfp},
@samp{arm1156t2-s}, @samp{arm1156t2f-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
-@samp{cortex-a5}, @samp{cortex-a8}, @samp{cortex-a9},
+@samp{cortex-a5}, @samp{cortex-a8}, @samp{cortex-a9}, @samp{cortex-a15},
@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-m4}, @samp{cortex-m3},
@samp{cortex-m1},
@samp{cortex-m0},
restricting which instructions can be used, it specifies that GCC should
tune the performance of the code as if the target were of the type
specified in this option, but still choosing the instructions that it
-will generate based on the cpu specified by a @option{-mcpu=} option.
+will generate based on the CPU specified by a @option{-mcpu=} option.
For some ARM implementations better performance can be obtained by using
this option.
@itemx -dynamic
@itemx -exported_symbols_list
@itemx -filelist
+@need 800
@itemx -flat_namespace
@itemx -force_flat_namespace
@itemx -headerpad_max_install_names
@itemx -multi_module
@itemx -multiply_defined
@itemx -multiply_defined_unused
+@need 800
@itemx -noall_load
@itemx -no_dead_strip_inits_and_terms
@itemx -nofixprebinding
@itemx -prebind
@itemx -prebind_all_twolevel_modules
@itemx -private_bundle
+@need 800
@itemx -read_only_relocs
@itemx -sectalign
@itemx -sectobjectsymbols
@itemx -sectorder
@itemx -segaddr
@itemx -segs_read_only_addr
+@need 800
@itemx -segs_read_write_addr
@itemx -seg_addr_table
@itemx -seg_addr_table_filename
@itemx -single_module
@itemx -static
@itemx -sub_library
+@need 800
@itemx -sub_umbrella
@itemx -twolevel_namespace
@itemx -umbrella
@var{cpu-type} are:
@table @emph
@item generic
-Produce code optimized for the most common IA32/AMD64/EM64T processors.
+Produce code optimized for the most common IA32/@/AMD64/@/EM64T processors.
If you know the CPU on which your code will run, then you should use
the corresponding @option{-mtune} option instead of
@option{-mtune=generic}. But, if you do not know exactly what CPU users
@item core2
Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
+@item corei7
+Intel Core i7 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1
+and SSE4.2 instruction set support.
+@item corei7-avx
+Intel Core i7 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, AVX, AES and PCLMUL instruction set support.
@item atom
Intel Atom CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
@code{sqrt} instructions for the 387. Specify this option to avoid
generating those instructions. This option is the default on FreeBSD,
OpenBSD and NetBSD@. This option is overridden when @option{-march}
-indicates that the target cpu will always have an FPU and so the
+indicates that the target CPU will always have an FPU and so the
instruction will not need emulation. As of revision 2.6.1, these
instructions are not generated unless you also use the
@option{-funsafe-math-optimizations} switch.
modules with the same value, including any libraries. This includes
the system libraries and startup modules.
+@item -mvect8-ret-in-mem
+@opindex mvect8-ret-in-mem
+Return 8-byte vectors in memory instead of MMX registers. This is the
+default on Solaris@tie{}8 and 9 and VxWorks to match the ABI of the Sun
+Studio compilers until version 12. Later compiler versions (starting
+with Studio 12 Update@tie{}1) follow the ABI used by other x86 targets, which
+is the default on Solaris@tie{}10 and later. @emph{Only} use this option if
+you need to remain compatible with existing code produced by those
+previous compiler versions or older versions of GCC.
+
@item -mpc32
@itemx -mpc64
@itemx -mpc80
@itemx -mssse3
@itemx -mno-ssse3
@itemx -msse4.1
+@need 800
@itemx -mno-sse4.1
@itemx -msse4.2
@itemx -mno-sse4.2
@itemx -maes
@itemx -mno-aes
@itemx -mpclmul
+@need 800
@itemx -mno-pclmul
@itemx -mfsgsbase
@itemx -mno-fsgsbase
@itemx -msse4a
@itemx -mno-sse4a
@itemx -mfma4
+@need 800
@itemx -mno-fma4
@itemx -mxop
@itemx -mno-xop
@itemx -mno-popcnt
@itemx -mabm
@itemx -mno-abm
+@itemx -mbmi
+@itemx -mno-bmi
+@itemx -mtbm
+@itemx -mno-tbm
@opindex mmmx
@opindex mno-mmx
@opindex msse
@opindex mno-3dnow
These switches enable or disable the use of instructions in the MMX,
SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, FSGSBASE, RDRND,
-F16C, SSE4A, FMA4, XOP, LWP, ABM or 3DNow!@: extended instruction sets.
+F16C, SSE4A, FMA4, XOP, LWP, ABM, BMI, or 3DNow!@: extended instruction sets.
These extensions are also available as built-in functions: see
@ref{X86 Built-in Functions}, for details of the functions enabled and
disabled by these switches.
instructions can be suppressed with the @option{-mno-cld} compiler option
in this case.
+@item -mvzeroupper
+@opindex mvzeroupper
+This option instructs GCC to emit a @code{vzeroupper} instruction
+before a transfer of control flow out of the function to minimize
+AVX to SSE transition penalty as well as remove unnecessary zeroupper
+intrinsics.
+
@item -mcx16
@opindex mcx16
This option will enable GCC to use CMPXCHG16B instruction in generated code.
counter call before prologue.
Note: On x86 architectures the attribute @code{ms_hook_prologue}
isn't possible at the moment for @option{-mfentry} and @option{-pg}.
+
+@item -m8bit-idiv
+@itemx -mno-8bit-idiv
+@opindex 8bit-idiv
+On some processors, like Intel Atom, 8bit unsigned integer divide is
+much faster than 32bit/64bit integer divide. This option will generate a
+runt-time check. If both dividend and divisor are within range of 0
+to 255, 8bit unsigned integer divide will be used instead of
+32bit/64bit integer divide.
+
@end table
These @samp{-m} switches are supported in addition to the above
@end table
+@node MicroBlaze Options
+@subsection MicroBlaze Options
+@cindex MicroBlaze Options
+
+@table @gcctabopt
+
+@item -msoft-float
+@opindex msoft-float
+Use software emulation for floating point (default).
+
+@item -mhard-float
+@opindex mhard-float
+Use hardware floating point instructions.
+
+@item -mmemcpy
+@opindex mmemcpy
+Do not optimize block moves, use @code{memcpy}.
+
+@item -mno-clearbss
+@opindex mno-clearbss
+This option is deprecated. Use @option{-fno-zero-initialized-in-bss} instead.
+
+@item -mcpu=@var{cpu-type}
+@opindex mcpu=
+Use features of and schedule code for given CPU.
+Supported values are in the format @samp{v@var{X}.@var{YY}.@var{Z}},
+where @var{X} is a major version, @var{YY} is the minor version, and
+@var{Z} is compatibility code. Example values are @samp{v3.00.a},
+@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v5.00.b}, @samp{v6.00.a}.
+
+@item -mxl-soft-mul
+@opindex mxl-soft-mul
+Use software multiply emulation (default).
+
+@item -mxl-soft-div
+@opindex mxl-soft-div
+Use software emulation for divides (default).
+
+@item -mxl-barrel-shift
+@opindex mxl-barrel-shift
+Use the hardware barrel shifter.
+
+@item -mxl-pattern-compare
+@opindex mxl-pattern-compare
+Use pattern compare instructions.
+
+@item -msmall-divides
+@opindex msmall-divides
+Use table lookup optimization for small signed integer divisions.
+
+@item -mxl-stack-check
+@opindex mxl-stack-check
+This option is deprecated. Use -fstack-check instead.
+
+@item -mxl-gp-opt
+@opindex mxl-gp-opt
+Use GP relative sdata/sbss sections.
+
+@item -mxl-multiply-high
+@opindex mxl-multiply-high
+Use multiply high instructions for high part of 32x32 multiply.
+
+@item -mxl-float-convert
+@opindex mxl-float-convert
+Use hardware floating point conversion instructions.
+
+@item -mxl-float-sqrt
+@opindex mxl-float-sqrt
+Use hardware floating point square root instruction.
+
+@item -mxl-mode-@var{app-model}
+Select application model @var{app-model}. Valid models are
+@table @samp
+@item executable
+normal executable (default), uses startup code @file{crt0.o}.
+
+@item xmdstub
+for use with Xilinx Microprocessor Debugger (XMD) based
+software intrusive debug agent called xmdstub. This uses startup file
+@file{crt1.o} and sets the start address of the program to be 0x800.
+
+@item bootstrap
+for applications that are loaded using a bootloader.
+This model uses startup file @file{crt2.o} which does not contain a processor
+reset vector handler. This is suitable for transferring control on a
+processor reset to the bootloader rather than the application.
+
+@item novectors
+for applications that do not require any of the
+MicroBlaze vectors. This option may be useful for applications running
+within a monitoring application. This model uses @file{crt3.o} as a startup file.
+@end table
+
+Option @option{-xl-mode-@var{app-model}} is a deprecated alias for
+@option{-mxl-mode-@var{app-model}}.
+
+@end table
+
@node MIPS Options
@subsection MIPS Options
@cindex MIPS options
@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1},
@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
@samp{1004kc}, @samp{1004kf2_1}, @samp{1004kf1_1},
-@samp{loongson2e}, @samp{loongson2f},
+@samp{loongson2e}, @samp{loongson2f}, @samp{loongson3a},
@samp{m4k},
@samp{octeon},
@samp{orion},
can use @option{-mgp32} to get 32-bit code instead.
For information about the O64 ABI, see
-@w{@uref{http://gcc.gnu.org/projects/mipso64-abi.html}}.
+@uref{http://gcc.gnu.org/@/projects/@/mipso64-abi.html}.
GCC supports a variant of the o32 ABI in which floating-point registers
are 64 rather than 32 bits wide. You can select this combination with
Do not generate code which uses features specific to the AM33 processor. This
is the default.
+@item -mam33-2
+@opindex mam33-2
+Generate code which uses features specific to the AM33/2.0 processor.
+
+@item -mam34
+@opindex mam34
+Generate code which uses features specific to the AM34 processor.
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Use the timing characteristics of the indicated CPU type when
+scheduling instructions. This does not change the targeted processor
+type. The CPU type must be one of @samp{mn10300}, @samp{am33},
+@samp{am33-2} or @samp{am34}.
+
@item -mreturn-pointer-on-d0
@opindex mreturn-pointer-on-d0
When generating a function which returns a pointer, return the pointer
has an effect when used on the command line for the final link step.
This option makes symbolic debugging impossible.
+
+@item -mliw
+@opindex mliw
+Allow the compiler to generate @emph{Long Instruction Word}
+instructions if the target is the @samp{AM33} or later. This is the
+default. This option defines the preprocessor macro @samp{__LIW__}.
+
+@item -mnoliw
+@opindex mnoliw
+Do not allow the compiler to generate @emph{Long Instruction Word}
+instructions. This option defines the preprocessor macro
+@samp{__NO_LIW__}.
+
@end table
@node PDP-11 Options
@opindex mbranch-cheap
Do not pretend that branches are expensive. This is the default.
-@item -msplit
-@opindex msplit
-Generate code for a system with split I&D@.
-
-@item -mno-split
-@opindex mno-split
-Generate code for a system without split I&D@. This is the default.
-
@item -munix-asm
@opindex munix-asm
Use Unix assembler syntax. This is the default when configured for
@itemx -mno-powerpc-gpopt
@itemx -mpowerpc-gfxopt
@itemx -mno-powerpc-gfxopt
+@need 800
@itemx -mpowerpc64
@itemx -mno-powerpc64
@itemx -mmfcrf
@itemx -mno-popcntd
@itemx -mfprnd
@itemx -mno-fprnd
+@need 800
@itemx -mcmpb
@itemx -mno-cmpb
@itemx -mmfpgpr
Generate PowerPC64 code for the small model: The TOC is limited to
64k.
+@item -mcmodel=medium
+@opindex mcmodel=medium
+Generate PowerPC64 code for the medium model: The TOC and other static
+data may be up to a total of 4G in size.
+
@item -mcmodel=large
@opindex mcmodel=large
Generate PowerPC64 code for the large model: The TOC may be up to 4G
@opindex mfused-madd
@opindex mno-fused-madd
Generate code that uses (does not use) the floating point multiply and
-accumulate instructions. These instructions are generated by default if
-hardware floating is used.
+accumulate instructions. These instructions are generated by default
+if hardware floating point is used. The machine dependent
+@option{-mfused-madd} option is now mapped to the machine independent
+@option{-ffp-contract=fast} option, and @option{-mno-fused-madd} is
+mapped to @option{-ffp-contract=off}.
@item -mmulhw
@itemx -mno-mulhw
resulting code is suitable for applications, but not shared
libraries.
+@item -msingle-pic-base
+@opindex msingle-pic-base
+Treat the register used for PIC addressing as read-only, rather than
+loading it in the prologue for each function. The run-time system is
+responsible for initializing this register with an appropriate value
+before execution begins.
+
@item -mprioritize-restricted-insns=@var{priority}
@opindex mprioritize-restricted-insns
This option controls the priority that is assigned to
@opindex mrecip=opt
This option allows to control which reciprocal estimate instructions
may be used. @var{opt} is a comma separated list of options, that may
-be preceeded by a @code{!} to invert the option:
+be preceded by a @code{!} to invert the option:
@code{all}: enable all estimate instructions,
-@code{default}: enable the default instructions, equvalent to @option{-mrecip},
+@code{default}: enable the default instructions, equivalent to @option{-mrecip},
@code{none}: disable all estimate instructions, equivalent to @option{-mno-recip};
@code{div}: enable the reciprocal approximation instructions for both single and double precision;
@code{divf}: enable the single precision reciprocal approximation instructions;
for power7. Both @option{-ftree-vectorize} and
@option{-funsafe-math-optimizations} have to be enabled. The MASS
libraries will have to be specified at link time.
+
+@item -mfriz
+@itemx -mno-friz
+@opindex mfriz
+Generate (do not generate) the @code{friz} instruction when the
+@option{-funsafe-math-optimizations} option is used to optimize
+rounding a floating point value to 64-bit integer and back to floating
+point. The @code{friz} instruction does not return the same value if
+the floating point number is too large to fit in an integer.
@end table
@node RX Options
@opindex -mcpu
Selects the type of RX CPU to be targeted. Currently three types are
supported, the generic @var{RX600} and @var{RX200} series hardware and
-the specific @var{RX610} cpu. The default is @var{RX600}.
+the specific @var{RX610} CPU. The default is @var{RX600}.
The only difference between @var{RX600} and @var{RX610} is that the
@var{RX610} does not support the @code{MVTIPL} instruction.
@opindex mbig-endian-data
@opindex mlittle-endian-data
Store data (but not code) in the big-endian format. The default is
-@option{-mlittle-endian-data}, ie to store data in the little endian
+@option{-mlittle-endian-data}, i.e.@: to store data in the little endian
format.
@item -msmall-data-limit=@var{N}
of symbol loads. The default is @option{-mno-invalid-symbols}.
@end table
+@node Solaris 2 Options
+@subsection Solaris 2 Options
+@cindex Solaris 2 options
+
+These @samp{-m} options are supported on Solaris 2:
+
+@table @gcctabopt
+@item -mimpure-text
+@opindex mimpure-text
+@option{-mimpure-text}, used in addition to @option{-shared}, tells
+the compiler to not pass @option{-z text} to the linker when linking a
+shared object. Using this option, you can link position-dependent
+code into a shared object.
+
+@option{-mimpure-text} suppresses the ``relocations remain against
+allocatable but non-writable sections'' linker error message.
+However, the necessary relocations will trigger copy-on-write, and the
+shared object is not actually shared across processes. Instead of
+using @option{-mimpure-text}, you should compile all source code with
+@option{-fpic} or @option{-fPIC}.
+
+@end table
+
+These switches are supported in addition to the above on Solaris 2:
+
+@table @gcctabopt
+@item -pthreads
+@opindex pthreads
+Add support for multithreading using the POSIX threads library. This
+option sets flags for both the preprocessor and linker. This option does
+not affect the thread safety of object code produced by the compiler or
+that of libraries supplied with it.
+
+@item -pthread
+@opindex pthread
+This is a synonym for @option{-pthreads}.
+@end table
+
@node SPARC Options
@subsection SPARC Options
@cindex SPARC options
acknowledges that their resulting code will not be directly in line with
the rules of the ABI@.
-@item -mimpure-text
-@opindex mimpure-text
-@option{-mimpure-text}, used in addition to @option{-shared}, tells
-the compiler to not pass @option{-z text} to the linker when linking a
-shared object. Using this option, you can link position-dependent
-code into a shared object.
-
-@option{-mimpure-text} suppresses the ``relocations remain against
-allocatable but non-writable sections'' linker error message.
-However, the necessary relocations will trigger copy-on-write, and the
-shared object is not actually shared across processes. Instead of
-using @option{-mimpure-text}, you should compile all source code with
-@option{-fpic} or @option{-fPIC}.
-
-This option is only available on SunOS and Solaris.
-
@item -mcpu=@var{cpu_type}
@opindex mcpu
Set the instruction set, register set, and instruction scheduling parameters
for machine type @var{cpu_type}. Supported values for @var{cpu_type} are
-@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{sparclite},
-@samp{f930}, @samp{f934}, @samp{hypersparc}, @samp{sparclite86x},
+@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{hypersparc},
+@samp{leon}, @samp{sparclite}, @samp{f930}, @samp{f934}, @samp{sparclite86x},
@samp{sparclet}, @samp{tsc701}, @samp{v9}, @samp{ultrasparc},
@samp{ultrasparc3}, @samp{niagara} and @samp{niagara2}.
@smallexample
v7: cypress
- v8: supersparc, hypersparc
+ v8: supersparc, hypersparc, leon
sparclite: f930, f934, sparclite86x
sparclet: tsc701
v9: ultrasparc, ultrasparc3, niagara, niagara2
The same values for @option{-mcpu=@var{cpu_type}} can be used for
@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}, @samp{ultrasparc},
-@samp{ultrasparc3}, @samp{niagara}, and @samp{niagara2}.
+that select a particular CPU implementation. Those are @samp{cypress},
+@samp{supersparc}, @samp{hypersparc}, @samp{leon}, @samp{f930}, @samp{f934},
+@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc}, @samp{ultrasparc3},
+@samp{niagara}, and @samp{niagara2}.
@item -mv8plus
@itemx -mno-v8plus
Otherwise, assume no such offset is present.
@end table
-These switches are supported in addition to the above on Solaris:
-
-@table @gcctabopt
-@item -threads
-@opindex threads
-Add support for multithreading using the Solaris threads library. This
-option sets flags for both the preprocessor and linker. This option does
-not affect the thread safety of object code produced by the compiler or
-that of libraries supplied with it.
-
-@item -pthreads
-@opindex pthreads
-Add support for multithreading using the POSIX threads library. This
-option sets flags for both the preprocessor and linker. This option does
-not affect the thread safety of object code produced by the compiler or
-that of libraries supplied with it.
-
-@item -pthread
-@opindex pthread
-This is a synonym for @option{-pthreads}.
-@end table
-
@node SPU Options
@subsection SPU Options
@cindex SPU options
Specify that the target processor is the V850E1. The preprocessor
constants @samp{__v850e1__} and @samp{__v850e__} will be defined if
+@item -mv850es
+@opindex mv850es
+Specify that the target processor is the V850ES. This is an alias for
+the @option{-mv850e1} option.
+
@item -mv850e
@opindex mv850e
Specify that the target processor is the V850E@. The preprocessor
required for console applications.
This is the default behavior for Cygwin and MinGW targets.
-@item -mcygwin
-@opindex mcygwin
-This option is available for Cygwin targets. It specifies that
-the Cygwin internal interface is to be used for predefined
-preprocessor macros, C runtime libraries and related linker
-paths and options. For Cygwin targets this is the default behavior.
-This option is deprecated and will be removed in a future release.
-
-@item -mno-cygwin
-@opindex mno-cygwin
-This option is available for Cygwin targets. It specifies that
-the MinGW internal interface is to be used instead of Cygwin's, by
-setting MinGW-related predefined macros and linker paths and default
-library options.
-This option is deprecated and will be removed in a future release.
-
@item -mdll
@opindex mdll
This option is available for Cygwin and MinGW targets. It
if the @var{file} parameter is a substring of the file name, it is
considered to be a match.
-For example,
-@code{-finstrument-functions-exclude-file-list=/bits/stl,include/sys}
+For example:
+
+@smallexample
+-finstrument-functions-exclude-file-list=/bits/stl,include/sys
+@end smallexample
+
+@noindent
will exclude any inline function defined in files whose pathnames
contain @code{/bits/stl} or @code{include/sys}.
@option{-Wl,--defsym,__stack_limit=0x7ffe0000} to enforce a stack limit
of 128KB@. Note that this may only work with the GNU linker.
+@item -fsplit-stack
+@opindex fsplit-stack
+Generate code to automatically split the stack before it overflows.
+The resulting program has a discontiguous stack which can only
+overflow if the program is unable to allocate any more memory. This
+is most useful when running threaded programs, as it is no longer
+necessary to calculate a good stack size to use for each thread. This
+is currently only implemented for the i386 and x86_64 backends running
+GNU/Linux.
+
+When code compiled with @option{-fsplit-stack} calls code compiled
+without @option{-fsplit-stack}, there may not be much stack space
+available for the latter code to run. If compiling all code,
+including library code, with @option{-fsplit-stack} is not an option,
+then the linker can fix up these calls so that the code compiled
+without @option{-fsplit-stack} always has a large stack. Support for
+this is implemented in the gold linker in GNU binutils release 2.21
+and later.
+
@item -fleading-underscore
@opindex fleading-underscore
This option and its counterpart, @option{-fno-leading-underscore}, forcibly
It is @strong{strongly} recommended that you use this in any shared objects
you distribute.
-Despite the nomenclature, @code{default} always means public ie;
+Despite the nomenclature, @code{default} always means public; i.e.,
available to be linked against from outside the shared object.
@code{protected} and @code{internal} are pretty useless in real-world
usage so the only other commonly used option will be @code{hidden}.
@samp{#pragma GCC visibility pop}.
Bear in mind that symbol visibility should be viewed @strong{as
part of the API interface contract} and thus all new code should
-always specify visibility when it is not the default ie; declarations
+always specify visibility when it is not the default; i.e., declarations
only for use within the local DSO should @strong{always} be marked explicitly
as hidden as so to avoid PLT indirection overheads---making this
abundantly clear also aids readability and self-documentation of the code.
the DSOs.
An overview of these techniques, their benefits and how to use them
-is at @w{@uref{http://gcc.gnu.org/wiki/Visibility}}.
+is at @uref{http://gcc.gnu.org/@/wiki/@/Visibility}.
@item -fstrict-volatile-bitfields
+@opindex fstrict-volatile-bitfields
This option should be used if accesses to volatile bitfields (or other
structure fields, although the compiler usually honors those types
-anyway) should use a single access in a mode of the same size as the
-container's type, aligned to a natural alignment if possible. For
+anyway) should use a single access of the width of the
+field's type, aligned to a natural alignment if possible. For
example, targets with memory-mapped peripheral registers might require
all such accesses to be 16 bits wide; with this flag the user could
declare all peripheral bitfields as ``unsigned short'' (assuming short
any portion of the bitfield, or memory-mapped registers unrelated to
the one being updated.
-If the target requires strict alignment, and honoring the container
+If the target requires strict alignment, and honoring the field
type would require violating this alignment, a warning is issued.
-However, the access happens as the user requested, under the
-assumption that the user knows something about the target hardware
-that GCC is unaware of.
+If the field has @code{packed} attribute, the access is done without
+honoring the field type. If the field doesn't have @code{packed}
+attribute, the access is done honoring the field type. In both cases,
+GCC assumes that the user knows something about the target hardware
+that it is unaware of.
The default value of this option is determined by the application binary
interface for the target processor.
@gccoptlist{-fmessage-length= -fpreprocessed -fsched-interblock @gol
-fsched-spec -fsched-spec-load -fsched-spec-load-dangerous @gol
--fsched-verbose=<number> -fschedule-insns -fvisibility= @gol
+-fsched-verbose=@var{number} -fschedule-insns -fvisibility= @gol
-pedantic-errors}
@end itemize
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