@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+@c 2000, 2001, 2002, 2003, 2004, 2005, 2006 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 INCLUDE
+@include gcc-vers.texi
+@c man end
+
@c man begin COPYRIGHT
-Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997,
-1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2 or
[@option{-I}@var{dir}@dots{}] [@option{-L}@var{dir}@dots{}]
[@option{-D}@var{macro}[=@var{defn}]@dots{}] [@option{-U}@var{macro}]
[@option{-f}@var{option}@dots{}] [@option{-m}@var{machine-option}@dots{}]
- [@option{-o} @var{outfile}] @var{infile}@dots{}
+ [@option{-o} @var{outfile}] [@@@var{file}] @var{infile}@dots{}
Only the most useful options are listed here; see below for the
remainder. @samp{g++} accepts mostly the same options as @samp{gcc}.
Many options have long names starting with @samp{-f} or with
@samp{-W}---for example,
-@option{-fstrength-reduce}, @option{-Wformat} and so on. Most of
+@option{-fmove-loop-invariants}, @option{-Wformat} and so on. Most of
these have both positive and negative forms; the negative form of
@option{-ffoo} would be @option{-fno-foo}. This manual documents
only one of these two forms, whichever one is not the default.
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
@gccoptlist{-c -S -E -o @var{file} -combine -pipe -pass-exit-codes @gol
--x @var{language} -v -### --help --target-help --version}
+-x @var{language} -v -### --help --target-help --version @@@var{file}}
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@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 -fno-const-strings @gol
+-fconserve-space -ffriend-injection @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
-ffor-scope -fno-for-scope -fno-gnu-keywords @gol
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @gol
--w -Wextra -Wall -Waggregate-return -Wno-attributes @gol
+-w -Wextra -Wall -Waggregate-return -Walways-true -Wno-attributes @gol
-Wc++-compat -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment @gol
-Wconversion -Wno-deprecated-declarations @gol
-Wdisabled-optimization -Wno-div-by-zero -Wno-endif-labels @gol
--Werror -Werror-implicit-function-declaration @gol
+-Werror -Werror-* -Werror-implicit-function-declaration @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-extra-args -Wformat-nonliteral @gol
-Wformat-security -Wformat-y2k @gol
-Wmain -Wmissing-braces -Wmissing-field-initializers @gol
-Wmissing-format-attribute -Wmissing-include-dirs @gol
-Wmissing-noreturn @gol
--Wno-multichar -Wnonnull -Wpacked -Wpadded @gol
+-Wno-multichar -Wnonnull -Woverlength-strings -Wpacked -Wpadded @gol
-Wparentheses -Wpointer-arith -Wno-pointer-to-int-cast @gol
-Wredundant-decls @gol
-Wreturn-type -Wsequence-point -Wshadow @gol
-Wsign-compare -Wstack-protector @gol
-Wstrict-aliasing -Wstrict-aliasing=2 @gol
+-Wstring-literal-comparison @gol
-Wswitch -Wswitch-default -Wswitch-enum @gol
-Wsystem-headers -Wtrigraphs -Wundef -Wuninitialized @gol
-Wunknown-pragmas -Wno-pragmas -Wunreachable-code @gol
-Wunused -Wunused-function -Wunused-label -Wunused-parameter @gol
-Wunused-value -Wunused-variable -Wvariadic-macros @gol
--Wwrite-strings}
+-Wvolatile-register-var -Wwrite-strings}
@item C-only Warning Options
@gccoptlist{-Wbad-function-cast -Wmissing-declarations @gol
-Wmissing-prototypes -Wnested-externs -Wold-style-definition @gol
-Wstrict-prototypes -Wtraditional @gol
--Wdeclaration-after-statement -Wno-pointer-sign}
+-Wdeclaration-after-statement -Wpointer-sign}
@item Debugging Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
-ftree-vectorizer-verbose=@var{n} @gol
-fdump-tree-storeccp@r{[}-@var{n}@r{]} @gol
-feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
--feliminate-unused-debug-symbols -fmem-report -fprofile-arcs @gol
+-feliminate-unused-debug-symbols -femit-class-debug-always @gol
+-fmem-report -fprofile-arcs @gol
-frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-ftest-coverage -ftime-report -fvar-tracking @gol
-g -g@var{level} -gcoff -gdwarf-2 @gol
-fexpensive-optimizations -ffast-math -ffloat-store @gol
-fforce-addr -ffunction-sections @gol
-fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload @gol
--floop-optimize -fcrossjumping -fif-conversion -fif-conversion2 @gol
--finline-functions -finline-limit=@var{n} -fkeep-inline-functions @gol
+-fcrossjumping -fif-conversion -fif-conversion2 @gol
+-finline-functions -finline-functions-called-once @gol
+-finline-limit=@var{n} -fkeep-inline-functions @gol
-fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
-fmodulo-sched -fno-branch-count-reg @gol
--fno-default-inline -fno-defer-pop -floop-optimize2 -fmove-loop-invariants @gol
+-fno-default-inline -fno-defer-pop -fmove-loop-invariants @gol
-fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
-funsafe-math-optimizations -funsafe-loop-optimizations -ffinite-math-only @gol
--fno-trapping-math -fno-zero-initialized-in-bss @gol
+-fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
-fomit-frame-pointer -foptimize-register-move @gol
-foptimize-sibling-calls -fprefetch-loop-arrays @gol
-fprofile-generate -fprofile-use @gol
-fregmove -frename-registers @gol
-freorder-blocks -freorder-blocks-and-partition -freorder-functions @gol
--frerun-cse-after-loop -frerun-loop-opt @gol
--frounding-math -fschedule-insns -fschedule-insns2 @gol
+-frerun-cse-after-loop @gol
+-frounding-math -frtl-abstract-sequences @gol
+-fschedule-insns -fschedule-insns2 @gol
-fno-sched-interblock -fno-sched-spec -fsched-spec-load @gol
-fsched-spec-load-dangerous @gol
-fsched-stalled-insns=@var{n} -fsched-stalled-insns-dep=@var{n} @gol
-fsched2-use-superblocks @gol
-fsched2-use-traces -freschedule-modulo-scheduled-loops @gol
--fsignaling-nans -fsingle-precision-constant @gol
+-fsection-anchors -fsignaling-nans -fsingle-precision-constant @gol
-fstack-protector -fstack-protector-all @gol
--fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps @gol
+-fstrict-aliasing -ftracer -fthread-jumps @gol
-funroll-all-loops -funroll-loops -fpeel-loops @gol
-fsplit-ivs-in-unroller -funswitch-loops @gol
-fvariable-expansion-in-unroller @gol
-ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts @gol
-ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink @gol
-ftree-ch -ftree-sra -ftree-ter -ftree-lrs -ftree-fre -ftree-vectorize @gol
--ftree-salias -fweb @gol
+-ftree-vect-loop-version -ftree-salias -fipa-pta -fweb @gol
-ftree-copy-prop -ftree-store-ccp -ftree-store-copy-prop -fwhole-program @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
-include @var{file} -imacros @var{file} @gol
-iprefix @var{file} -iwithprefix @var{dir} @gol
-iwithprefixbefore @var{dir} -isystem @var{dir} @gol
--isysroot @var{dir} @gol
+-imultilib @var{dir} -isysroot @var{dir} @gol
-M -MM -MF -MG -MP -MQ -MT -nostdinc @gol
-P -fworking-directory -remap @gol
-trigraphs -undef -U@var{macro} -Wp,@var{option} @gol
-mpoke-function-name @gol
-mthumb -marm @gol
-mtpcs-frame -mtpcs-leaf-frame @gol
--mcaller-super-interworking -mcallee-super-interworking}
+-mcaller-super-interworking -mcallee-super-interworking @gol
+-mtp=@var{name}}
@emph{AVR Options}
@gccoptlist{-mmcu=@var{mcu} -msize -minit-stack=@var{n} -mno-interrupts @gol
-single_module -static -sub_library -sub_umbrella @gol
-twolevel_namespace -umbrella -undefined @gol
-unexported_symbols_list -weak_reference_mismatches @gol
--whatsloaded -F -gused -gfull -mmacosx-min-version=@var{version} @gol
+-whatsloaded -F -gused -gfull -mmacosx-version-min=@var{version} @gol
-mone-byte-bool}
@emph{DEC Alpha Options}
-mTLS -mtls @gol
-mcpu=@var{cpu}}
+@emph{GNU/Linux Options}
+@gccoptlist{-muclibc}
+
@emph{H8/300 Options}
@gccoptlist{-mrelax -mh -ms -mn -mint32 -malign-300}
-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 -msse3 -m3dnow @gol
+-mmmx -msse -msse2 -msse3 -m3dnow -msselibm @gol
-mthreads -mno-align-stringops -minline-all-stringops @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -msseregparm @gol
-minline-sqrt-min-latency -minline-sqrt-max-throughput @gol
-mno-dwarf2-asm -mearly-stop-bits @gol
-mfixed-range=@var{register-range} -mtls-size=@var{tls-size} @gol
--mtune=@var{cpu-type} -mt -pthread -milp32 -mlp64}
+-mtune=@var{cpu-type} -mt -pthread -milp32 -mlp64 @gol
+-mno-sched-br-data-spec -msched-ar-data-spec -mno-sched-control-spec @gol
+-msched-br-in-data-spec -msched-ar-in-data-spec -msched-in-control-spec @gol
+-msched-ldc -mno-sched-control-ldc -mno-sched-spec-verbose @gol
+-mno-sched-prefer-non-data-spec-insns @gol
+-mno-sched-prefer-non-control-spec-insns @gol
+-mno-sched-count-spec-in-critical-path}
@emph{M32R/D Options}
@gccoptlist{-m32r2 -m32rx -m32r @gol
@emph{M680x0 Options}
@gccoptlist{-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040 @gol
--m68060 -mcpu32 -m5200 -m68881 -mbitfield -mc68000 -mc68020 @gol
+-m68060 -mcpu32 -m5200 -mcfv4e -m68881 -mbitfield @gol
+-mc68000 -mc68020 @gol
-mnobitfield -mrtd -mshort -msoft-float -mpcrel @gol
-malign-int -mstrict-align -msep-data -mno-sep-data @gol
-mshared-library-id=n -mid-shared-library -mno-id-shared-library}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 -mips64 @gol
-mips16 -mno-mips16 -mabi=@var{abi} -mabicalls -mno-abicalls @gol
--mxgot -mno-xgot -mgp32 -mgp64 -mfp32 -mfp64 @gol
--mhard-float -msoft-float -msingle-float -mdouble-float @gol
--mdsp -mpaired-single -mips3d @gol
+-mshared -mno-shared -mxgot -mno-xgot -mgp32 -mgp64 @gol
+-mfp32 -mfp64 -mhard-float -msoft-float @gol
+-msingle-float -mdouble-float -mdsp -mpaired-single -mips3d @gol
-mlong64 -mlong32 -msym32 -mno-sym32 @gol
-G@var{num} -membedded-data -mno-embedded-data @gol
-muninit-const-in-rodata -mno-uninit-const-in-rodata @gol
@gccoptlist{-mmult-bug -mno-mult-bug @gol
-mam33 -mno-am33 @gol
-mam33-2 -mno-am33-2 @gol
+-mreturn-pointer-on-d0 @gol
-mno-crt0 -mrelax}
+@emph{MT Options}
+@gccoptlist{-mno-crt0 -mbacc -msim @gol
+-march=@var{cpu-type} }
+
@emph{PDP-11 Options}
@gccoptlist{-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 @gol
-mbcopy -mbcopy-builtin -mint32 -mno-int16 @gol
-maltivec -mno-altivec @gol
-mpowerpc-gpopt -mno-powerpc-gpopt @gol
-mpowerpc-gfxopt -mno-powerpc-gfxopt @gol
+-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mfprnd -mno-fprnd @gol
-mnew-mnemonics -mold-mnemonics @gol
-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc @gol
-m64 -m32 -mxl-compat -mno-xl-compat -mpe @gol
-mspe -mno-spe @gol
-mspe=yes -mspe=no @gol
-mvrsave -mno-vrsave @gol
+-mmulhw -mno-mulhw @gol
+-mdlmzb -mno-dlmzb @gol
-mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double @gol
-mprototype -mno-prototype @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
@emph{S/390 and zSeries Options}
@gccoptlist{-mtune=@var{cpu-type} -march=@var{cpu-type} @gol
--mhard-float -msoft-float -mbackchain -mno-backchain @gol
--mpacked-stack -mno-packed-stack @gol
+-mhard-float -msoft-float -mlong-double-64 -mlong-double-128 @gol
+-mbackchain -mno-backchain -mpacked-stack -mno-packed-stack @gol
-msmall-exec -mno-small-exec -mmvcle -mno-mvcle @gol
-m64 -m31 -mdebug -mno-debug -mesa -mzarch @gol
-mtpf-trace -mno-tpf-trace -mfused-madd -mno-fused-madd @gol
-mstack-bias -mno-stack-bias @gol
-munaligned-doubles -mno-unaligned-doubles @gol
-mv8plus -mno-v8plus -mvis -mno-vis
--threads -pthreads}
+-threads -pthreads -pthread}
@emph{System V Options}
@gccoptlist{-Qy -Qn -YP,@var{paths} -Ym,@var{dir}}
-fno-common -fno-ident @gol
-fpcc-struct-return -fpic -fPIC -fpie -fPIE @gol
-fno-jump-tables @gol
--freg-struct-return -fshared-data -fshort-enums @gol
+-freg-struct-return -fshort-enums @gol
-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
-fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fleading-underscore @gol
--ftls-model=@var{model} @gol
+-fargument-noalias-global -fargument-noalias-anything
+-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
--fvisibility}
+-fvisibility -fopenmp}
@end table
@menu
@item @var{file}.f
@itemx @var{file}.for
@itemx @var{file}.FOR
-Fortran source code which should not be preprocessed.
+Fixed form Fortran source code which should not be preprocessed.
@item @var{file}.F
@itemx @var{file}.fpp
@itemx @var{file}.FPP
-Fortran source code which must be preprocessed (with the traditional
+Fixed form Fortran source code which must be preprocessed (with the traditional
preprocessor).
-@item @var{file}.r
-Fortran source code which must be preprocessed with a RATFOR
-preprocessor (not included with GCC)@.
-
@item @var{file}.f90
@itemx @var{file}.f95
-Fortran 90/95 source code which should not be preprocessed.
+Free form Fortran source code which should not be preprocessed.
@item @var{file}.F90
@itemx @var{file}.F95
-Fortran 90/95 source code which must be preprocessed (with the
+Free form Fortran source code which must be preprocessed (with the
traditional preprocessor).
@c FIXME: Descriptions of Java file types.
@c Pascal:
@c @var{file}.p
@c @var{file}.pas
+@c Ratfor:
+@c @var{file}.r
@item @var{file}.s
Assembler code.
objective-c++ objective-c++-header objective-c++-cpp-output
assembler assembler-with-cpp
ada
-f77 f77-cpp-input ratfor
-f95
+f77 f77-cpp-input
+f95 f95-cpp-input
java
treelang
@end smallexample
phase of the compiler returns a non-success return code. If you specify
@option{-pass-exit-codes}, the @command{gcc} program will instead return with
numerically highest error produced by any phase that returned an error
-indication.
+indication. The C, C++, and Fortran frontends return 4, if an internal
+compiler error is encountered.
@end table
If you only want some of the stages of compilation, you can use
@item --version
@opindex version
Display the version number and copyrights of the invoked GCC@.
+
+@include @value{srcdir}/../libiberty/at-file.texi
@end table
@node Invoking G++
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 -fno-const-strings
-@opindex fno-const-strings
-Give string constants type @code{char *} instead of type @code{const
-char *}. By default, G++ uses type @code{const char *} as required by
-the standard. Even if you use @option{-fno-const-strings}, you cannot
-actually modify the value of a string constant.
+@item -ffriend-injection
+@opindex ffriend-injection
+Inject friend functions into the enclosing namespace, so that they are
+visible outside the scope of the class in which they are declared.
+Friend functions were documented to work this way in the old Annotated
+C++ Reference Manual, and versions of G++ before 4.1 always worked
+that way. However, in ISO C++ a friend function which is not declared
+in an enclosing scope can only be found using argument dependent
+lookup. This option causes friends to be injected as they were in
+earlier releases.
-This option might be removed in a future release of G++. For maximum
-portability, you should structure your code so that it works with
-string constants that have type @code{const char *}.
+This option is for compatibility, and may be removed in a future
+release of G++.
@item -fno-elide-constructors
@opindex fno-elide-constructors
@item -fno-enforce-eh-specs
@opindex fno-enforce-eh-specs
-Don't check for violation of exception specifications at runtime. This
-option violates the C++ standard, but may be useful for reducing code
-size in production builds, much like defining @samp{NDEBUG}. The compiler
-will still optimize based on the exception specifications.
+Don't generate code to check for violation of exception specifications
+at runtime. This option violates the C++ standard, but may be useful
+for reducing code size in production builds, much like defining
+@samp{NDEBUG}. This does not give user code permission to throw
+exceptions in violation of the exception specifications; the compiler
+will still optimize based on the specifications, so throwing an
+unexpected exception will result in undefined behavior.
@item -ffor-scope
@itemx -fno-for-scope
destructors, but will only work if your C library supports
@code{__cxa_atexit}.
+@item -fno-use-cxa-get-exception-ptr
+@opindex fno-use-cxa-get-exception-ptr
+Don't use the @code{__cxa_get_exception_ptr} runtime routine. This
+will cause @code{std::uncaught_exception} to be incorrect, but is necessary
+if the runtime routine is not available.
+
@item -fvisibility-inlines-hidden
@opindex fvisibility-inlines-hidden
Causes all inlined methods to be marked with
@item -Wnon-virtual-dtor @r{(C++ only)}
@opindex Wnon-virtual-dtor
Warn when a class appears to be polymorphic, thereby requiring a virtual
-destructor, yet it declares a non-virtual one.
-This warning is enabled by @option{-Wall}.
+destructor, yet it declares a non-virtual one. This warning is also
+enabled if -Weffc++ is specified.
@item -Wreorder @r{(C++ only)}
@opindex Wreorder
@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. Currently, this option is only
-available in conjunction with the NeXT runtime on Mac OS X 10.3 and later.
+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 @{
@item -Wsequence-point
@opindex Wsequence-point
Warn about code that may have undefined semantics because of violations
-of sequence point rules in the C standard.
-
-The C standard defines the order in which expressions in a C program are
-evaluated in terms of @dfn{sequence points}, which represent a partial
-ordering between the execution of parts of the program: those executed
-before the sequence point, and those executed after it. These occur
-after the evaluation of a full expression (one which is not part of a
-larger expression), after the evaluation of the first operand of a
+of sequence point rules in the C and C++ standards.
+
+The C and C++ standards defines the order in which expressions in a C/C++
+program are evaluated in terms of @dfn{sequence points}, which represent
+a partial ordering between the execution of parts of the program: those
+executed before the sequence point, and those executed after it. These
+occur after the evaluation of a full expression (one which is not part
+of a larger expression), after the evaluation of the first operand of a
@code{&&}, @code{||}, @code{? :} or @code{,} (comma) operator, before a
function is called (but after the evaluation of its arguments and the
expression denoting the called function), and in certain other places.
It is not specified when between sequence points modifications to the
values of objects take effect. Programs whose behavior depends on this
-have undefined behavior; the C standard specifies that ``Between the
-previous and next sequence point an object shall have its stored value
-modified at most once by the evaluation of an expression. Furthermore,
-the prior value shall be read only to determine the value to be
-stored.''. If a program breaks these rules, the results on any
+have undefined behavior; the C and C++ standards specify that ``Between
+the previous and next sequence point an object shall have its stored
+value modified at most once by the evaluation of an expression.
+Furthermore, the prior value shall be read only to determine the value
+to be stored.''. If a program breaks these rules, the results on any
particular implementation are entirely unpredictable.
Examples of code with undefined behavior are @code{a = a++;}, @code{a[n]
result, but in general it has been found fairly effective at detecting
this sort of problem in programs.
-The present implementation of this option only works for C programs. A
-future implementation may also work for C++ programs.
-
-The C standard is worded confusingly, therefore there is some debate
+The standard is worded confusingly, therefore there is some debate
over the precise meaning of the sequence point rules in subtle cases.
Links to discussions of the problem, including proposed formal
definitions, may be found on the GCC readings page, at
@w{@uref{http://gcc.gnu.org/readings.html}}.
-This warning is enabled by @option{-Wall}.
+This warning is enabled by @option{-Wall} for C and C++.
@item -Wreturn-type
@opindex Wreturn-type
@item -Wunused-function
@opindex Wunused-function
Warn whenever a static function is declared but not defined or a
-non\-inline static function is unused.
+non-inline static function is unused.
This warning is enabled by @option{-Wall}.
@item -Wunused-label
char[@var{length}]} so that
copying the address of one into a non-@code{const} @code{char *}
pointer will get a warning; when compiling C++, warn about the
-deprecated conversion from string constants to @code{char *}.
+deprecated conversion from string literals to @code{char *}. This
+warning, by default, is enabled for C++ programs.
These warnings will help you find at
compile time code that can try to write into a string constant, but
only if you have been very careful about using @code{const} in
called. (In languages where you can return an array, this also elicits
a warning.)
+@item -Walways-true
+@opindex Walways-true
+Warn about comparisons which are always true such as testing if
+unsigned values are greater than or equal to zero. This warning is
+enabled by @option{-Wall}.
+
@item -Wno-attributes
@opindex Wno-attributes
@opindex Wattributes
alternate syntax when in pedantic ISO C99 mode. This is default.
To inhibit the warning messages, use @option{-Wno-variadic-macros}.
+@item -Wvolatile-register-var
+@opindex Wvolatile-register-var
+@opindex Wno-volatile-register-var
+Warn if a register variable is declared volatile. The volatile
+modifier does not inhibit all optimizations that may eliminate reads
+and/or writes to register variables.
+
@item -Wdisabled-optimization
@opindex Wdisabled-optimization
Warn if a requested optimization pass is disabled. This warning does
complex; GCC will refuse to optimize programs when the optimization
itself is likely to take inordinate amounts of time.
-@item -Wno-pointer-sign
+@item -Wpointer-sign
+@opindex Wpointer-sign
@opindex Wno-pointer-sign
-Don't warn for pointer argument passing or assignment with different signedness.
-Only useful in the negative form since this warning is enabled by default.
-This option is only supported for C and Objective-C@.
+Warn for pointer argument passing or assignment with different signedness.
+This option is only supported for C and Objective-C@. It is implied by
+@option{-Wall} and by @option{-pedantic}, which can be disabled with
+@option{-Wno-pointer-sign}.
@item -Werror
@opindex Werror
Make all warnings into errors.
+@item -Werror=
+@opindex Werror=
+Make the specified warning into an errors. The specifier for a
+warning is appended, for example @option{-Werror=switch} turns the
+warnings controlled by @option{-Wswitch} into errors. This switch
+takes a 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.
+
+Note that specifying @option{-Werror=}@var{foo} automatically implies
+@option{-W}@var{foo}. However, @option{-Wno-error=}@var{foo} does not
+imply anything.
+
@item -Wstack-protector
+@opindex Wstack-protector
This option is only active when @option{-fstack-protector} is active. It
warns about functions that will not be protected against stack smashing.
+@item -Wstring-literal-comparison
+@opindex Wstring-literal-comparison
+Warn about suspicious comparisons to string literal constants. In C,
+direct comparisons against the memory address of a string literal, such
+as @code{if (x == "abc")}, typically indicate a programmer error, and
+even when intentional, result in unspecified behavior and are not portable.
+Usually these warnings alert that the programmer intended to use
+@code{strcmp}. This warning is enabled by @option{-Wall}.
+
+@item -Woverlength-strings
+@opindex Woverlength-strings
+Warn about string constants which are longer than the ``minimum
+maximum'' length specified in the C standard. Modern compilers
+generally allow string constants which are much longer than the
+standard's minimum limit, but very portable programs should avoid
+using longer strings.
+
+The limit applies @emph{after} string constant concatenation, and does
+not count the trailing NUL@. In C89, the limit was 509 characters; in
+C99, it was raised to 4095. C++98 does not specify a normative
+minimum maximum, so we do not diagnose overlength strings in C++@.
+
+This option is implied by @option{-pedantic}, and can be disabled with
+@option{-Wno-overlength-strings}.
@end table
@node Debugging Options
Produce debugging information in stabs format (if that is supported),
for only symbols that are actually used.
+@item -femit-class-debug-always
+Instead of emitting debugging information for a C++ class in only one
+object file, emit it in all object files using the class. This option
+should be used only with debuggers that are unable to handle the way GCC
+normally emits debugging information for classes because using this
+option will increase the size of debugging information by as much as a
+factor of two.
+
@item -gstabs+
@opindex gstabs+
Produce debugging information in stabs format (if that is supported),
@opindex dA
Annotate the assembler output with miscellaneous debugging information.
-@item -db
-@itemx -fdump-rtl-bp
-@opindex db
-@opindex fdump-rtl-bp
-Dump after computing branch probabilities, to @file{@var{file}.09.bp}.
-
@item -dB
@itemx -fdump-rtl-bbro
@opindex dB
@opindex fdump-rtl-bbro
-Dump after block reordering, to @file{@var{file}.30.bbro}.
+Dump after block reordering, to @file{@var{file}.148r.bbro}.
@item -dc
@itemx -fdump-rtl-combine
@opindex dc
@opindex fdump-rtl-combine
-Dump after instruction combination, to the file @file{@var{file}.17.combine}.
+Dump after instruction combination, to the file @file{@var{file}.129r.combine}.
@item -dC
@itemx -fdump-rtl-ce1
@opindex fdump-rtl-ce1
@opindex fdump-rtl-ce2
@option{-dC} and @option{-fdump-rtl-ce1} enable dumping after the
-first if conversion, to the file @file{@var{file}.11.ce1}. @option{-dC}
+first if conversion, to the file @file{@var{file}.117r.ce1}. @option{-dC}
and @option{-fdump-rtl-ce2} enable dumping after the second if
-conversion, to the file @file{@var{file}.18.ce2}.
+conversion, to the file @file{@var{file}.130r.ce2}.
@item -dd
@itemx -fdump-rtl-btl
@itemx -fdump-rtl-ce3
@opindex dE
@opindex fdump-rtl-ce3
-Dump after the third if conversion, to @file{@var{file}.28.ce3}.
+Dump after the third if conversion, to @file{@var{file}.146r.ce3}.
@item -df
@itemx -fdump-rtl-cfg
@opindex fdump-rtl-cfg
@opindex fdump-rtl-life
@option{-df} and @option{-fdump-rtl-cfg} enable dumping after control
-and data flow analysis, to @file{@var{file}.08.cfg}. @option{-df}
+and data flow analysis, to @file{@var{file}.116r.cfg}. @option{-df}
and @option{-fdump-rtl-cfg} enable dumping dump after life analysis,
-to @file{@var{file}.16.life}.
+to @file{@var{file}.128r.life1} and @file{@var{file}.135r.life2}.
@item -dg
@itemx -fdump-rtl-greg
@opindex dg
@opindex fdump-rtl-greg
-Dump after global register allocation, to @file{@var{file}.23.greg}.
+Dump after global register allocation, to @file{@var{file}.139r.greg}.
@item -dG
@itemx -fdump-rtl-gcse
@opindex fdump-rtl-gcse
@opindex fdump-rtl-bypass
@option{-dG} and @option{-fdump-rtl-gcse} enable dumping after GCSE, to
-@file{@var{file}.05.gcse}. @option{-dG} and @option{-fdump-rtl-bypass}
+@file{@var{file}.114r.gcse}. @option{-dG} and @option{-fdump-rtl-bypass}
enable dumping after jump bypassing and control flow optimizations, to
-@file{@var{file}.07.bypass}.
+@file{@var{file}.115r.bypass}.
@item -dh
@itemx -fdump-rtl-eh
@itemx -fdump-rtl-sibling
@opindex di
@opindex fdump-rtl-sibling
-Dump after sibling call optimizations, to @file{@var{file}.01.sibling}.
+Dump after sibling call optimizations, to @file{@var{file}.106r.sibling}.
@item -dj
@itemx -fdump-rtl-jump
@opindex dj
@opindex fdump-rtl-jump
-Dump after the first jump optimization, to @file{@var{file}.03.jump}.
+Dump after the first jump optimization, to @file{@var{file}.112r.jump}.
@item -dk
@itemx -fdump-rtl-stack
@opindex dk
@opindex fdump-rtl-stack
-Dump after conversion from registers to stack, to @file{@var{file}.33.stack}.
+Dump after conversion from registers to stack, to @file{@var{file}.152r.stack}.
@item -dl
@itemx -fdump-rtl-lreg
@opindex dl
@opindex fdump-rtl-lreg
-Dump after local register allocation, to @file{@var{file}.22.lreg}.
+Dump after local register allocation, to @file{@var{file}.138r.lreg}.
@item -dL
-@itemx -fdump-rtl-loop
@itemx -fdump-rtl-loop2
@opindex dL
-@opindex fdump-rtl-loop
@opindex fdump-rtl-loop2
-@option{-dL} and @option{-fdump-rtl-loop} enable dumping after the first
-loop optimization pass, to @file{@var{file}.06.loop}. @option{-dL} and
-@option{-fdump-rtl-loop2} enable dumping after the second pass, to
-@file{@var{file}.13.loop2}.
+@option{-dL} and @option{-fdump-rtl-loop2} enable dumping after the
+loop optimization pass, to @file{@var{file}.119r.loop2},
+@file{@var{file}.120r.loop2_init},
+@file{@var{file}.121r.loop2_invariant}, and
+@file{@var{file}.125r.loop2_done}.
@item -dm
@itemx -fdump-rtl-sms
@opindex dm
@opindex fdump-rtl-sms
-Dump after modulo scheduling, to @file{@var{file}.20.sms}.
+Dump after modulo scheduling, to @file{@var{file}.136r.sms}.
@item -dM
@itemx -fdump-rtl-mach
@opindex dM
@opindex fdump-rtl-mach
Dump after performing the machine dependent reorganization pass, to
-@file{@var{file}.35.mach}.
+@file{@var{file}.155r.mach}.
@item -dn
@itemx -fdump-rtl-rnreg
@opindex dn
@opindex fdump-rtl-rnreg
-Dump after register renumbering, to @file{@var{file}.29.rnreg}.
+Dump after register renumbering, to @file{@var{file}.147r.rnreg}.
@item -dN
@itemx -fdump-rtl-regmove
@opindex dN
@opindex fdump-rtl-regmove
-Dump after the register move pass, to @file{@var{file}.19.regmove}.
+Dump after the register move pass, to @file{@var{file}.132r.regmove}.
@item -do
@itemx -fdump-rtl-postreload
@itemx -fdump-rtl-expand
@opindex dr
@opindex fdump-rtl-expand
-Dump after RTL generation, to @file{@var{file}.00.expand}.
+Dump after RTL generation, to @file{@var{file}.104r.expand}.
@item -dR
@itemx -fdump-rtl-sched2
@opindex dR
@opindex fdump-rtl-sched2
-Dump after the second scheduling pass, to @file{@var{file}.32.sched2}.
+Dump after the second scheduling pass, to @file{@var{file}.150r.sched2}.
@item -ds
@itemx -fdump-rtl-cse
@opindex ds
@opindex fdump-rtl-cse
Dump after CSE (including the jump optimization that sometimes follows
-CSE), to @file{@var{file}.04.cse}.
+CSE), to @file{@var{file}.113r.cse}.
@item -dS
@itemx -fdump-rtl-sched
@opindex dt
@opindex fdump-rtl-cse2
Dump after the second CSE pass (including the jump optimization that
-sometimes follows CSE), to @file{@var{file}.15.cse2}.
+sometimes follows CSE), to @file{@var{file}.127r.cse2}.
@item -dT
@itemx -fdump-rtl-tracer
@opindex dT
@opindex fdump-rtl-tracer
-Dump after running tracer, to @file{@var{file}.12.tracer}.
+Dump after running tracer, to @file{@var{file}.118r.tracer}.
@item -dV
@itemx -fdump-rtl-vpt
@option{-dV} and @option{-fdump-rtl-vpt} enable dumping after the value
profile transformations, to @file{@var{file}.10.vpt}. @option{-dV}
and @option{-fdump-rtl-vartrack} enable dumping after variable tracking,
-to @file{@var{file}.34.vartrack}.
+to @file{@var{file}.154r.vartrack}.
@item -dw
@itemx -fdump-rtl-flow2
@opindex dw
@opindex fdump-rtl-flow2
-Dump after the second flow pass, to @file{@var{file}.26.flow2}.
+Dump after the second flow pass, to @file{@var{file}.142r.flow2}.
@item -dz
@itemx -fdump-rtl-peephole2
@opindex dz
@opindex fdump-rtl-peephole2
-Dump after the peephole pass, to @file{@var{file}.27.peephole2}.
+Dump after the peephole pass, to @file{@var{file}.145r.peephole2}.
@item -dZ
@itemx -fdump-rtl-web
@opindex dZ
@opindex fdump-rtl-web
-Dump after live range splitting, to @file{@var{file}.14.web}.
+Dump after live range splitting, to @file{@var{file}.126r.web}.
@item -da
@itemx -fdump-rtl-all
and inlining decisions.
@end table
-@item -fdump-tree-@var{switch} @r{(C and C++ only)}
-@itemx -fdump-tree-@var{switch}-@var{options} @r{(C and C++ only)}
+@item -fdump-tree-@var{switch}
+@itemx -fdump-tree-@var{switch}-@var{options}
@opindex fdump-tree
Control the dumping at various stages of processing the intermediate
language tree to a file. The file name is generated by appending a switch
@item -ftree-vectorizer-verbose=@var{n}
@opindex ftree-vectorizer-verbose
This option controls the amount of debugging output the vectorizer prints.
-This information is written to standard error, unless @option{-fdump-tree-all}
-or @option{-fdump-tree-vect} is specified, in which case it is output to the
-usual dump listing file, @file{.vect}.
+This information is written to standard error, unless
+@option{-fdump-tree-all} or @option{-fdump-tree-vect} is specified,
+in which case it is output to the usual dump listing file, @file{.vect}.
+For @var{n}=0 no diagnostic information is reported.
+If @var{n}=1 the vectorizer reports each loop that got vectorized,
+and the total number of loops that got vectorized.
+If @var{n}=2 the vectorizer also reports non-vectorized loops that passed
+the first analysis phase (vect_analyze_loop_form) - i.e. countable,
+inner-most, single-bb, single-entry/exit loops. This is the same verbosity
+level that @option{-fdump-tree-vect-stats} uses.
+Higher verbosity levels mean either more information dumped for each
+reported loop, or same amount of information reported for more loops:
+If @var{n}=3, alignment related information is added to the reports.
+If @var{n}=4, data-references related information (e.g. memory dependences,
+memory access-patterns) is added to the reports.
+If @var{n}=5, the vectorizer reports also non-vectorized inner-most loops
+that did not pass the first analysis phase (i.e. may not be countable, or
+may have complicated control-flow).
+If @var{n}=6, the vectorizer reports also non-vectorized nested loops.
+For @var{n}=7, all the information the vectorizer generates during its
+analysis and transformation is reported. This is the same verbosity level
+that @option{-fdump-tree-vect-details} uses.
@item -frandom-seed=@var{string}
@opindex frandom-string
-fdelayed-branch @gol
-fguess-branch-probability @gol
-fcprop-registers @gol
--floop-optimize @gol
-fif-conversion @gol
-fif-conversion2 @gol
-ftree-ccp @gol
-fcse-follow-jumps -fcse-skip-blocks @gol
-fgcse -fgcse-lm @gol
-fexpensive-optimizations @gol
--fstrength-reduce @gol
--frerun-cse-after-loop -frerun-loop-opt @gol
+-frerun-cse-after-loop @gol
-fcaller-saves @gol
-fpeephole2 @gol
-fschedule-insns -fschedule-insns2 @gol
@option{-Os} disables the following optimization flags:
@gccoptlist{-falign-functions -falign-jumps -falign-loops @gol
--falign-labels -freorder-blocks -freorder-blocks-and-partition -fprefetch-loop-arrays}
+-falign-labels -freorder-blocks -freorder-blocks-and-partition @gol
+-fprefetch-loop-arrays -ftree-vect-loop-version}
If you use multiple @option{-O} options, with or without level numbers,
the last such option is the one that is effective.
Enabled at level @option{-O3}.
+@item -finline-functions-called-once
+@opindex finline-functions-called-once
+Consider all @code{static} functions called once for inlining into their
+caller even if they are not marked @code{inline}. If a call to a given
+function is integrated, then the function is not output as assembler code
+in its own right.
+
+Enabled if @option{-funit-at-a-time} is enabled.
+
@item -fearly-inlining
@opindex fearly-inlining
Inline functions marked by @code{always_inline} and functions whose body seems
This option is only meaningful on architectures that support such
instructions, which include x86, PowerPC, IA-64 and S/390.
-The default is @option{-fbranch-count-reg}, enabled when
-@option{-fstrength-reduce} is enabled.
+The default is @option{-fbranch-count-reg}.
@item -fno-function-cse
@opindex fno-function-cse
some protection against outright memory corrupting writes, but allows
erroneously read data to propagate within a program.
-@item -fstrength-reduce
-@opindex fstrength-reduce
-Perform the optimizations of loop strength reduction and
-elimination of iteration variables.
-
-Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
-
@item -fthread-jumps
@opindex fthread-jumps
Perform optimizations where we check to see if a jump branches to a
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
-@item -frerun-loop-opt
-@opindex frerun-loop-opt
-Run the loop optimizer twice.
-
-Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
-
@item -fgcse
@opindex fgcse
Perform a global common subexpression elimination pass.
pass is performed after reload. The purpose of this pass is to cleanup
redundant spilling.
-@item -floop-optimize
-@opindex floop-optimize
-Perform loop optimizations: move constant expressions out of loops, simplify
-exit test conditions and optionally do strength-reduction as well.
-
-Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
-
-@item -floop-optimize2
-@opindex floop-optimize2
-Perform loop optimizations using the new loop optimizer. The optimizations
-(loop unrolling, peeling and unswitching, loop invariant motion) are enabled
-by separate flags.
-
@item -funsafe-loop-optimizations
@opindex funsafe-loop-optimizations
If given, the loop optimizer will assume that loop indices do not
Perform structural alias analysis on trees. This flag
is enabled by default at @option{-O} and higher.
+@item -fipa-pta
+Perform interprocedural pointer analysis.
+
@item -ftree-sink
Perform forward store motion on trees. This flag is
enabled by default at @option{-O} and higher.
default at @option{-O} and higher.
@item -ftree-dominator-opts
-Perform dead code elimination (DCE) on trees. This flag is enabled by
-default at @option{-O} and higher.
+Perform a variety of simple scalar cleanups (constant/copy
+propagation, redundancy elimination, range propagation and expression
+simplification) based on a dominator tree traversal. This also
+performs jump threading (to reduce jumps to jumps). This flag is
+enabled by default at @option{-O} and higher.
@item -ftree-ch
Perform loop header copying on trees. This is beneficial since it increases
@item -ftree-vectorize
Perform loop vectorization on trees.
+@item -ftree-vect-loop-version
+@opindex ftree-vect-loop-version
+Perform loop versioning when doing loop vectorization on trees. When a loop
+appears to be vectorizable except that data alignment or data dependence cannot
+be determined at compile time then vectorized and non-vectorized versions of
+the loop are generated along with runtime checks for alignment or dependence
+to control which version is executed. This option is enabled by default
+except at level @option{-Os} where it is disabled.
+
@item -ftree-vrp
Perform Value Range Propagation on trees. This is similar to the
constant propagation pass, but instead of values, ranges of values are
@item -funroll-loops
@opindex funroll-loops
Unroll loops whose number of iterations can be determined at compile
-time or upon entry to the loop. @option{-funroll-loops} implies both
-@option{-fstrength-reduce} and @option{-frerun-cse-after-loop}. This
-option makes code larger, and may or may not make it run faster.
+time or upon entry to the loop. @option{-funroll-loops} implies
+@option{-frerun-cse-after-loop}. This option makes code larger,
+and may or may not make it run faster.
@item -funroll-all-loops
@opindex funroll-all-loops
If supported by the target machine, generate instructions to prefetch
memory to improve the performance of loops that access large arrays.
-These options may generate better or worse code; results are highly
+This option may generate better or worse code; results are highly
dependent on the structure of loops within the source code.
+Disabled at level @option{-Os}.
+
@item -fno-peephole
@itemx -fno-peephole2
@opindex fno-peephole
Parse the whole compilation unit before starting to produce code.
This allows some extra optimizations to take place but consumes
more memory (in general). There are some compatibility issues
-with @emph{unit-at-at-time} mode:
+with @emph{unit-at-a-time} mode:
@itemize @bullet
@item
enabling @emph{unit-at-a-time} mode may change the order
in which functions, variables, and top-level @code{asm} statements
are emitted, and will likely break code relying on some particular
ordering. The majority of such top-level @code{asm} statements,
-though, can be replaced by @code{section} attributes.
+though, can be replaced by @code{section} attributes. The
+@option{fno-toplevel-reorder} option may be used to keep the ordering
+used in the input file, at the cost of some optimizations.
@item
@emph{unit-at-a-time} mode removes unreferenced static variables
Enabled at levels @option{-O2}, @option{-O3}.
+@item -fno-toplevel-reorder
+Do not reorder top-level functions, variables, and @code{asm}
+statements. Output them in the same order that they appear in the
+input file. When this option is used, unreferenced static variables
+will not be removed. This option is intended to support existing code
+which relies on a particular ordering. For new code, it is better to
+use attributes.
+
@item -fweb
@opindex fweb
Constructs webs as commonly used for register allocation purposes and assign
generally profitable only with profile feedback available.
The following options are enabled: @code{-fbranch-probabilities}, @code{-fvpt},
-@code{-funroll-loops}, @code{-fpeel-loops}, @code{-ftracer},
-@code{-fno-loop-optimize}.
+@code{-funroll-loops}, @code{-fpeel-loops}, @code{-ftracer}
@end table
using C99's @code{FENV_ACCESS} pragma. This command line option
will be used to specify the default state for @code{FENV_ACCESS}.
+@item -frtl-abstract-sequences
+@opindex frtl-abstract-sequences
+It is a size optimization method. This option is to find identical
+sequences of code, which can be turned into pseudo-procedures and
+then replace all occurrences with calls to the newly created
+subroutine. It is kind of an opposite of @option{-finline-functions}.
+This optimization runs at RTL level.
+
@item -fsignaling-nans
@opindex fsignaling-nans
Compile code assuming that IEEE signaling NaNs may generate user-visible
@item -fmove-loop-invariants
@opindex fmove-loop-invariants
-Enables the loop invariant motion pass in the new loop optimizer. Enabled
+Enables the loop invariant motion pass in the RTL loop optimizer. Enabled
at level @option{-O1}
@item -funswitch-loops
Move branches with loop invariant conditions out of the loop, with duplicates
of the loop on both branches (modified according to result of the condition).
-@item -fprefetch-loop-arrays
-@opindex fprefetch-loop-arrays
-If supported by the target machine, generate instructions to prefetch
-memory to improve the performance of loops that access large arrays.
-
-Disabled at level @option{-Os}.
-
@item -ffunction-sections
@itemx -fdata-sections
@opindex ffunction-sections
@item -fstack-protector-all
Like @option{-fstack-protector} except that all functions are protected.
+@item -fsection-anchors
+@opindex fsection-anchors
+Try to reduce the number of symbolic address calculations by using
+shared ``anchor'' symbols to address nearby objects. This transformation
+can help to reduce the number of GOT entries and GOT accesses on some
+targets.
+
+For example, the implementation of the following function @code{foo}:
+
+@smallexample
+static int a, b, c;
+int foo (void) @{ return a + b + c; @}
+@end smallexample
+
+would usually calculate the addresses of all three variables, but if you
+compile it with @option{-fsection-anchors}, it will access the variables
+from a common anchor point instead. The effect is similar to the
+following pseudocode (which isn't valid C):
+
+@smallexample
+int foo (void)
+@{
+ register int *xr = &x;
+ return xr[&a - &x] + xr[&b - &x] + xr[&c - &x];
+@}
+@end smallexample
+
+Not all targets support this option.
+
@item --param @var{name}=@var{value}
@opindex param
In some places, GCC uses various constants to control the amount of
structure accesses for which structure aliasing will consider trying
to track each field. The default is 5
+@item salias-max-array-elements
+The maximum number of elements an array can have and its elements
+still be tracked individually by structure aliasing. The default is 4
+
@item sra-max-structure-size
The maximum structure size, in bytes, at which the scalar replacement
of aggregates (SRA) optimization will perform block copies. The
value is ignored in the case where all instructions in the block being
crossjumped from are matched. The default value is 5.
+@item max-grow-copy-bb-insns
+The maximum code size expansion factor when copying basic blocks
+instead of jumping. The expansion is relative to a jump instruction.
+The default value is 8.
+
@item max-goto-duplication-insns
The maximum number of instructions to duplicate to a block that jumps
to a computed goto. To avoid @math{O(N^2)} behavior in a number of
The default value is 100 which limits large function growth to 2.0 times
the original size.
+@item large-unit-insns
+The limit specifying large translation unit. Growth caused by inlining of
+units larger than this limit is limited by @option{--param inline-unit-growth}.
+For small units this might be too tight (consider unit consisting of function A
+that is inline and B that just calls A three time. If B is small relative to
+A, the growth of unit is 300\% and yet such inlining is very sane. For very
+large units consisting of small inlininable functions however the overall unit
+growth limit is needed to avoid exponential explosion of code size. Thus for
+smaller units, the size is increased to @option{--param large-unit-insns}
+before applying @option{--param inline-unit-growth}. The default is 10000
+
@item inline-unit-growth
Specifies maximal overall growth of the compilation unit caused by inlining.
This parameter is ignored when @option{-funit-at-a-time} is not used.
Bound on size of expressions used in the scalar evolutions analyzer.
Large expressions slow the analyzer.
+@item vect-max-version-checks
+The maximum number of runtime checks that can be performed when doing
+loop versioning in the vectorizer. See option ftree-vect-loop-version
+for more information.
+
@item max-iterations-to-track
The maximum number of iterations of a loop the brute force algorithm
Select fraction of the maximal frequency of executions of basic block in
function given basic block needs to have to be considered hot
+@item max-predicted-iterations
+The maximum number of loop iterations we predict statically. This is useful
+in cases where function contain single loop with known bound and other loop
+with unknown. We predict the known number of iterations correctly, while
+the unknown number of iterations average to roughly 10. This means that the
+loop without bounds would appear artificially cold relative to the other one.
+
@item tracer-dynamic-coverage
@itemx tracer-dynamic-coverage-feedback
Maximum number of basic blocks on path that cse considers. The default is 10.
+@item max-cse-insns
+The maximum instructions CSE process before flushing. The default is 1000.
+
@item global-var-threshold
Counts the number of function calls (@var{n}) and the number of
Increasing values mean more aggressive optimization, making the compile time
increase with probably slightly better performance. The default value is 500.
+@item max-flow-memory-location
+Similar as @option{max-cselib-memory-location} but for dataflow liveness.
+The default value is 100.
+
@item reorder-blocks-duplicate
@itemx reorder-blocks-duplicate-feedback
The maximum number of insns in a region to be considered for
interblock scheduling. The default value is 100.
+@item min-spec-prob
+The minimum probability (in percents) of reaching a source block
+for interblock speculative scheduling. The default value is 40.
+
+@item max-sched-extend-regions-iters
+The maximum number of iterations through CFG to extend regions.
+0 - disable region extension,
+N - do at most N iterations.
+The default value is 2.
+
+@item max-sched-insn-conflict-delay
+The maximum conflict delay for an insn to be considered for speculative motion.
+The default value is 3.
+
+@item sched-spec-prob-cutoff
+The minimal probability of speculation success (in percents), so that
+speculative insn will be scheduled.
+The default value is 40.
+
@item max-last-value-rtl
The maximum size measured as number of RTLs that can be recorded in an expression
The minimum size of buffers (i.e. arrays) that will receive stack smashing
protection when @option{-fstack-protection} is used.
+@item max-jump-thread-duplication-stmts
+Maximum number of statements allowed in a block that needs to be
+duplicated when threading jumps.
+
+@item max-fields-for-field-sensitive
+Maximum number of fields in a structure we will treat in
+a field sensitive manner during pointer analysis.
+
@end table
@end table
@item %I
Substitute any of @option{-iprefix} (made from @env{GCC_EXEC_PREFIX}),
-@option{-isysroot} (made from @env{TARGET_SYSTEM_ROOT}), and
+@option{-isysroot} (made from @env{TARGET_SYSTEM_ROOT}),
@option{-isystem} (made from @env{COMPILER_PATH} and @option{-B} options)
-as necessary.
+and @option{-imultilib} as necessary.
@item %s
Current argument is the name of a library or startup file of some sort.
* DEC Alpha Options::
* DEC Alpha/VMS Options::
* FRV Options::
+* GNU/Linux Options::
* H8/300 Options::
* HPPA Options::
* i386 and x86-64 Options::
* MIPS Options::
* MMIX Options::
* MN10300 Options::
+* MT Options::
* PDP-11 Options::
* PowerPC Options::
* RS/6000 and PowerPC Options::
@item -mabi=@var{name}
@opindex mabi
Generate code for the specified ABI@. Permissible values are: @samp{apcs-gnu},
-@samp{atpcs}, @samp{aapcs} and @samp{iwmmxt}.
+@samp{atpcs}, @samp{aapcs}, @samp{aapcs-linux} and @samp{iwmmxt}.
@item -mapcs-frame
@opindex mapcs-frame
compiled for interworking or not. There is a small overhead in the cost
of executing a function pointer if this option is enabled.
+@item -mtp=@var{name}
+@opindex mtp
+Specify the access model for the thread local storage pointer. The valid
+models are @option{soft}, which generates calls to @code{__aeabi_read_tp},
+@option{cp15}, which fetches the thread pointer from @code{cp15} directly
+(supported in the arm6k architecture), and @option{auto}, which uses the
+best available method for the selected processor. The default setting is
+@option{auto}.
+
@end table
@node AVR Options
@end table
+@node GNU/Linux Options
+@subsection GNU/Linux Options
+
+These @samp{-m} options are defined for GNU/Linux targets:
+
+@table @gcctabopt
+@item -mglibc
+@opindex mglibc
+Use the GNU C library instead of uClibc. This is the default except
+on @samp{*-*-linux-*uclibc*} targets.
+
+@item -muclibc
+@opindex muclibc
+Use uClibc instead of the GNU C library. This is the default on
+@samp{*-*-linux-*uclibc*} targets.
+@end table
+
@node H8/300 Options
@subsection H8/300 Options
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`}.
+using @samp{which `gcc -print-prog-name=ld`}. This option is only available
+on the 64 bit HP-UX GCC, i.e. configured with @samp{hppa*64*-*-hpux*}.
@item -mhp-ld
@opindex hp-ld
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`}.
+`gcc -print-prog-name=ld`}. This option is only available on the 64 bit
+HP-UX GCC, i.e. configured with @samp{hppa*64*-*-hpux*}.
@item -mlong-calls
@opindex mno-long-calls
for the ABI and the set of available instructions. The choices for
@var{cpu-type} are:
@table @emph
+@item generic
+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
+of your application will have, then you should use this option.
+
+As new processors are deployed in the marketplace, the behavior of this
+option will change. Therefore, if you upgrade to a newer version of
+GCC, the code generated option will change to reflect the processors
+that were most common when that version of GCC was released.
+
+There is no @option{-march=generic} option because @option{-march}
+indicates the instruction set the compiler can use, and there is no
+generic instruction set applicable to all processors. In contrast,
+@option{-mtune} indicates the processor (or, in this case, collection of
+processors) for which the code is optimized.
@item i386
Original Intel's i386 CPU@.
@item i486
Intel Pentium CPU with no MMX support.
@item pentium-mmx
Intel PentiumMMX CPU based on Pentium core with MMX instruction set support.
-@item i686, pentiumpro
+@item pentiumpro
Intel PentiumPro CPU@.
+@item i686
+Same as @code{generic}, but when used as @code{march} option, PentiumPro
+instruction set will be used, so the code will run on all i686 familly chips.
@item pentium2
Intel Pentium2 CPU based on PentiumPro core with MMX instruction set support.
@item pentium3, pentium3m
@item -masm=@var{dialect}
@opindex masm=@var{dialect}
-Output asm instructions using selected @var{dialect}. Supported choices are
-@samp{intel} or @samp{att} (the default one).
+Output asm instructions using selected @var{dialect}. Supported
+choices are @samp{intel} or @samp{att} (the default one). Darwin does
+not support @samp{intel}.
@item -mieee-fp
@itemx -mno-ieee-fp
@opindex mno-sse
@opindex m3dnow
@opindex mno-3dnow
-These switches enable or disable the use of built-in functions that allow
-direct access to the MMX, SSE, SSE2, SSE3 and 3Dnow extensions of the
-instruction set.
-
-@xref{X86 Built-in Functions}, for details of the functions enabled
-and disabled by these switches.
+These switches enable or disable the use of instructions in the MMX,
+SSE, SSE2 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.
To have SSE/SSE2 instructions generated automatically from floating-point
-code, see @option{-mfpmath=sse}.
+code (as opposed to 387 instructions), see @option{-mfpmath=sse}.
+
+These options will enable GCC to use these extended instructions in
+generated code, even without @option{-mfpmath=sse}. Applications which
+perform runtime CPU detection must compile separate files for each
+supported architecture, using the appropriate flags. In particular,
+the file containing the CPU detection code should be compiled without
+these options.
+
+@item -msselibm
+@opindex msselibm
+Use special versions of certain libm routines that come with an SSE
+ABI and an SSE implementation. Useful together with @option{-mfpmath=sse}
+to avoid moving values between SSE registers and the x87 FP stack.
@item -mpush-args
@itemx -mno-push-args
Specify bit size of immediate TLS offsets. Valid values are 14, 22, and
64.
-@item -mtune-arch=@var{cpu-type}
-@opindex mtune-arch
+@item -mtune=@var{cpu-type}
+@opindex mtune
Tune the instruction scheduling for a particular CPU, Valid values are
itanium, itanium1, merced, itanium2, and mckinley.
The 64-bit environment sets int to 32 bits and long and pointer
to 64 bits. These are HP-UX specific flags.
+@item -mno-sched-br-data-spec
+@itemx -msched-br-data-spec
+@opindex -mno-sched-br-data-spec
+@opindex -msched-br-data-spec
+(Dis/En)able data speculative scheduling before reload.
+This will result in generation of the ld.a instructions and
+the corresponding check instructions (ld.c / chk.a).
+The default is 'disable'.
+
+@item -msched-ar-data-spec
+@itemx -mno-sched-ar-data-spec
+@opindex -msched-ar-data-spec
+@opindex -mno-sched-ar-data-spec
+(En/Dis)able data speculative scheduling after reload.
+This will result in generation of the ld.a instructions and
+the corresponding check instructions (ld.c / chk.a).
+The default is 'enable'.
+
+@item -mno-sched-control-spec
+@itemx -msched-control-spec
+@opindex -mno-sched-control-spec
+@opindex -msched-control-spec
+(Dis/En)able control speculative scheduling. This feature is
+available only during region scheduling (i.e. before reload).
+This will result in generation of the ld.s instructions and
+the corresponding check instructions chk.s .
+The default is 'disable'.
+
+@item -msched-br-in-data-spec
+@itemx -mno-sched-br-in-data-spec
+@opindex -msched-br-in-data-spec
+@opindex -mno-sched-br-in-data-spec
+(En/Dis)able speculative scheduling of the instructions that
+are dependent on the data speculative loads before reload.
+This is effective only with @option{-msched-br-data-spec} enabled.
+The default is 'enable'.
+
+@item -msched-ar-in-data-spec
+@itemx -mno-sched-ar-in-data-spec
+@opindex -msched-ar-in-data-spec
+@opindex -mno-sched-ar-in-data-spec
+(En/Dis)able speculative scheduling of the instructions that
+are dependent on the data speculative loads after reload.
+This is effective only with @option{-msched-ar-data-spec} enabled.
+The default is 'enable'.
+
+@item -msched-in-control-spec
+@itemx -mno-sched-in-control-spec
+@opindex -msched-in-control-spec
+@opindex -mno-sched-in-control-spec
+(En/Dis)able speculative scheduling of the instructions that
+are dependent on the control speculative loads.
+This is effective only with @option{-msched-control-spec} enabled.
+The default is 'enable'.
+
+@item -msched-ldc
+@itemx -mno-sched-ldc
+@opindex -msched-ldc
+@opindex -mno-sched-ldc
+(En/Dis)able use of simple data speculation checks ld.c .
+If disabled, only chk.a instructions will be emitted to check
+data speculative loads.
+The default is 'enable'.
+
+@item -mno-sched-control-ldc
+@itemx -msched-control-ldc
+@opindex -mno-sched-control-ldc
+@opindex -msched-control-ldc
+(Dis/En)able use of ld.c instructions to check control speculative loads.
+If enabled, in case of control speculative load with no speculatively
+scheduled dependent instructions this load will be emitted as ld.sa and
+ld.c will be used to check it.
+The default is 'disable'.
+
+@item -mno-sched-spec-verbose
+@itemx -msched-spec-verbose
+@opindex -mno-sched-spec-verbose
+@opindex -msched-spec-verbose
+(Dis/En)able printing of the information about speculative motions.
+
+@item -mno-sched-prefer-non-data-spec-insns
+@itemx -msched-prefer-non-data-spec-insns
+@opindex -mno-sched-prefer-non-data-spec-insns
+@opindex -msched-prefer-non-data-spec-insns
+If enabled, data speculative instructions will be choosen for schedule
+only if there are no other choices at the moment. This will make
+the use of the data speculation much more conservative.
+The default is 'disable'.
+
+@item -mno-sched-prefer-non-control-spec-insns
+@itemx -msched-prefer-non-control-spec-insns
+@opindex -mno-sched-prefer-non-control-spec-insns
+@opindex -msched-prefer-non-control-spec-insns
+If enabled, control speculative instructions will be choosen for schedule
+only if there are no other choices at the moment. This will make
+the use of the control speculation much more conservative.
+The default is 'disable'.
+
+@item -mno-sched-count-spec-in-critical-path
+@itemx -msched-count-spec-in-critical-path
+@opindex -mno-sched-count-spec-in-critical-path
+@opindex -msched-count-spec-in-critical-path
+If enabled, speculative depedencies will be considered during
+computation of the instructions priorities. This will make the use of the
+speculation a bit more conservative.
+The default is 'disable'.
+
@end table
@node M32C Options
Use this option for microcontroller with a 5200 core, including
the MCF5202, MCF5203, MCF5204 and MCF5202.
+@item -mcfv4e
+@opindex mcfv4e
+Generate output for a ColdFire V4e family cpu (e.g.@: 547x/548x).
+This includes use of hardware floating point instructions.
@item -m68020-40
@opindex m68020-40
@itemx -mno-abicalls
@opindex mabicalls
@opindex mno-abicalls
-Generate (do not generate) SVR4-style position-independent code.
-@option{-mabicalls} is the default for SVR4-based systems.
+Generate (do not generate) code that is suitable for SVR4-style
+dynamic objects. @option{-mabicalls} is the default for SVR4-based
+systems.
+
+@item -mshared
+@itemx -mno-shared
+Generate (do not generate) code that is fully position-independent,
+and that can therefore be linked into shared libraries. This option
+only affects @option{-mabicalls}.
+
+All @option{-mabicalls} code has traditionally been position-independent,
+regardless of options like @option{-fPIC} and @option{-fpic}. However,
+as an extension, the GNU toolchain allows executables to use absolute
+accesses for locally-binding symbols. It can also use shorter GP
+initialization sequences and generate direct calls to locally-defined
+functions. This mode is selected by @option{-mno-shared}.
+
+@option{-mno-shared} depends on binutils 2.16 or higher and generates
+objects that can only be linked by the GNU linker. However, the option
+does not affect the ABI of the final executable; it only affects the ABI
+of relocatable objects. Using @option{-mno-shared} will generally make
+executables both smaller and quicker.
+
+@option{-mshared} is the default.
@item -mxgot
@itemx -mno-xgot
Do not generate code which uses features specific to the AM33 processor. This
is the default.
+@item -mreturn-pointer-on-d0
+@opindex mreturn-pointer-on-d0
+When generating a function which returns a pointer, return the pointer
+in both @code{a0} and @code{d0}. Otherwise, the pointer is returned
+only in a0, and attempts to call such functions without a prototype
+would result in errors. Note that this option is on by default; use
+@option{-mno-return-pointer-on-d0} to disable it.
+
@item -mno-crt0
@opindex mno-crt0
Do not link in the C run-time initialization object file.
This option makes symbolic debugging impossible.
@end table
+@node MT Options
+@subsection MT Options
+@cindex MT options
+
+These @option{-m} options are defined for Morpho MT architectures:
+
+@table @gcctabopt
+
+@item -march=@var{cpu-type}
+@opindex march
+Generate code that will run on @var{cpu-type}, which is the name of a system
+representing a certain processor type. Possible values for
+@var{cpu-type} are @samp{ms1-64-001}, @samp{ms1-16-002},
+@samp{ms1-16-003} and @samp{ms2}.
+
+When this option is not used, the default is @option{-march=ms1-16-002}.
+
+@item -mbacc
+@opindex mbacc
+Use byte loads and stores when generating code.
+
+@item -mno-bacc
+@opindex mno-bacc
+Do not use byte loads and stores when generating code.
+
+@item -msim
+@opindex msim
+Use simulator runtime
+
+@item -mno-crt0
+@opindex mno-crt0
+Do not link in the C run-time initialization object file
+@file{crti.o}. Other run-time initialization and termination files
+such as @file{startup.o} and @file{exit.o} are still included on the
+linker command line.
+
+@end table
+
@node PDP-11 Options
@subsection PDP-11 Options
@cindex PDP-11 Options
@itemx -mno-powerpc-gfxopt
@itemx -mpowerpc64
@itemx -mno-powerpc64
+@itemx -mmfcrf
+@itemx -mno-mfcrf
+@itemx -mpopcntb
+@itemx -mno-popcntb
+@itemx -mfprnd
+@itemx -mno-fprnd
@opindex mpower
@opindex mno-power
@opindex mpower2
@opindex mno-powerpc-gfxopt
@opindex mpowerpc64
@opindex mno-powerpc64
+@opindex mmfcrf
+@opindex mno-mfcrf
+@opindex mpopcntb
+@opindex mno-popcntb
+@opindex mfprnd
+@opindex mno-fprnd
GCC supports two related instruction set architectures for the
RS/6000 and PowerPC@. The @dfn{POWER} instruction set are those
instructions supported by the @samp{rios} chip set used in the original
RS/6000 systems and the @dfn{PowerPC} instruction set is the
-architecture of the Motorola MPC5xx, MPC6xx, MPC8xx microprocessors, and
-the IBM 4xx microprocessors.
+architecture of the Freescale MPC5xx, MPC6xx, MPC8xx microprocessors, and
+the IBM 4xx, 6xx, and follow-on microprocessors.
Neither architecture is a subset of the other. However there is a
large common subset of instructions supported by both. An MQ
use the optional PowerPC architecture instructions in the Graphics
group, including floating-point select.
+The @option{-mmfcrf} option allows GCC to generate the move from
+condition register field instruction implemented on the POWER4
+processor and other processors that support the PowerPC V2.01
+architecture.
+The @option{-mpopcntb} option allows GCC to generate the popcount and
+double precision FP reciprocal estimate instruction implemented on the
+POWER5 processor and other processors that support the PowerPC V2.02
+architecture.
+The @option{-mfprnd} option allows GCC to generate the FP round to
+integer instructions implemented on the POWER5+ processor and other
+processors that support the PowerPC V2.03 architecture.
+
The @option{-mpowerpc64} option allows GCC to generate the additional
64-bit instructions that are found in the full PowerPC64 architecture
and to treat GPRs as 64-bit, doubleword quantities. GCC defaults to
@samp{601}, @samp{602}, @samp{603}, @samp{603e}, @samp{604},
@samp{604e}, @samp{620}, @samp{630}, @samp{740}, @samp{7400},
@samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
-@samp{860}, @samp{970}, @samp{8540}, @samp{common}, @samp{ec603e}, @samp{G3},
+@samp{860}, @samp{970}, @samp{8540}, @samp{ec603e}, @samp{G3},
@samp{G4}, @samp{G5}, @samp{power}, @samp{power2}, @samp{power3},
-@samp{power4}, @samp{power5}, @samp{powerpc}, @samp{powerpc64},
+@samp{power4}, @samp{power5}, @samp{power5+},
+@samp{common}, @samp{powerpc}, @samp{powerpc64},
@samp{rios}, @samp{rios1}, @samp{rios2}, @samp{rsc}, and @samp{rs64}.
@option{-mcpu=common} selects a completely generic processor. Code
others.
The @option{-mcpu} options automatically enable or disable the
-following options: @option{-maltivec}, @option{-mhard-float},
-@option{-mmfcrf}, @option{-mmultiple}, @option{-mnew-mnemonics},
-@option{-mpower}, @option{-mpower2}, @option{-mpowerpc64},
-@option{-mpowerpc-gpopt}, @option{-mpowerpc-gfxopt},
-@option{-mstring}. The particular options set for any particular CPU
-will vary between compiler versions, depending on what setting seems
-to produce optimal code for that CPU; it doesn't necessarily reflect
-the actual hardware's capabilities. If you wish to set an individual
-option to a particular value, you may specify it after the
-@option{-mcpu} option, like @samp{-mcpu=970 -mno-altivec}.
+following options: @option{-maltivec}, @option{-mfprnd},
+@option{-mhard-float}, @option{-mmfcrf}, @option{-mmultiple},
+@option{-mnew-mnemonics}, @option{-mpopcntb}, @option{-mpower},
+@option{-mpower2}, @option{-mpowerpc64}, @option{-mpowerpc-gpopt},
+@option{-mpowerpc-gfxopt}, @option{-mstring}, @option{-mmulhw}, @option{dlmzb}.
+The particular options
+set for any particular CPU will vary between compiler versions,
+depending on what setting seems to produce optimal code for that CPU;
+it doesn't necessarily reflect the actual hardware's capabilities. If
+you wish to set an individual option to a particular value, you may
+specify it after the @option{-mcpu} option, like @samp{-mcpu=970
+-mno-altivec}.
On AIX, the @option{-maltivec} and @option{-mpowerpc64} options are
-not enabled or disabled by the @option{-mcpu} option at present, since
+not enabled or disabled by the @option{-mcpu} option at present because
AIX does not have full support for these options. You may still
enable or disable them individually if you're sure it'll work in your
environment.
@opindex mno-vrsave
Generate VRSAVE instructions when generating AltiVec code.
-@item -mabi=spe
-@opindex mabi=spe
-Extend the current ABI with SPE ABI extensions. This does not change
-the default ABI, instead it adds the SPE ABI extensions to the current
-ABI@.
-
-@item -mabi=no-spe
-@opindex mabi=no-spe
-Disable Booke SPE ABI extensions for the current ABI@.
-
@item -msecure-plt
@opindex msecure-plt
Generate code that allows ld and ld.so to build executables and shared
@itemx -mno-xl-compat
@opindex mxl-compat
@opindex mno-xl-compat
-Produce code that conforms more closely to IBM XLC semantics when using
-AIX-compatible ABI. Pass floating-point arguments to prototyped
-functions beyond the register save area (RSA) on the stack in addition
-to argument FPRs. Do not assume that most significant double in 128
-bit long double value is properly rounded when comparing values.
+Produce code that conforms more closely to IBM XL compiler semantics
+when using AIX-compatible ABI. Pass floating-point arguments to
+prototyped functions beyond the register save area (RSA) on the stack
+in addition to argument FPRs. Do not assume that most significant
+double in 128-bit long double value is properly rounded when comparing
+values and converting to double. Use XL symbol names for long double
+support routines.
The AIX calling convention was extended but not initially documented to
handle an obscure K&R C case of calling a function that takes the
-address of its arguments with fewer arguments than declared. AIX XL
+address of its arguments with fewer arguments than declared. IBM XL
compilers access floating point arguments which do not fit in the
RSA from the stack when a subroutine is compiled without
optimization. Because always storing floating-point arguments on the
stack is inefficient and rarely needed, this option is not enabled by
-default and only is necessary when calling subroutines compiled by AIX
+default and only is necessary when calling subroutines compiled by IBM
XL compilers without optimization.
@item -mpe
accumulate instructions. These instructions are generated by default if
hardware floating is used.
+@item -mmulhw
+@itemx -mno-mulhw
+@opindex mmulhw
+@opindex mno-mulhw
+Generate code that uses (does not use) the half-word multiply and
+multiply-accumulate instructions on the IBM 405 and 440 processors.
+These instructions are generated by default when targetting those
+processors.
+
+@item -mdlmzb
+@itemx -mno-dlmzb
+@opindex mdlmzb
+@opindex mno-dlmzb
+Generate code that uses (does not use) the string-search @samp{dlmzb}
+instruction on the IBM 405 and 440 processors. This instruction is
+generated by default when targetting those processors.
+
@item -mno-bit-align
@itemx -mbit-align
@opindex mno-bit-align
@opindex mabi
Extend the current ABI with a particular extension, or remove such extension.
Valid values are @var{altivec}, @var{no-altivec}, @var{spe},
-@var{no-spe}@.
+@var{no-spe}, @var{ibmlongdouble}, @var{ieeelongdouble}@.
+
+@item -mabi=spe
+@opindex mabi=spe
+Extend the current ABI with SPE ABI extensions. This does not change
+the default ABI, instead it adds the SPE ABI extensions to the current
+ABI@.
+
+@item -mabi=no-spe
+@opindex mabi=no-spe
+Disable Booke SPE ABI extensions for the current ABI@.
+
+@item -mabi=ibmlongdouble
+@opindex mabi=ibmlongdouble
+Change the current ABI to use IBM extended precision long double.
+This is a PowerPC 32-bit SYSV ABI option.
+
+@item -mabi=ieeelongdouble
+@opindex mabi=ieeelongdouble
+Change the current ABI to use IEEE extended precision long double.
+This is a PowerPC 32-bit Linux ABI option.
@item -mprototype
@itemx -mno-prototype
@item -msdata-data
@opindex msdata-data
-On System V.4 and embedded PowerPC systems, put small global and static
-data in the @samp{.sdata} section. Put small uninitialized global and
-static data in the @samp{.sbss} section. Do not use register @code{r13}
+On System V.4 and embedded PowerPC systems, put small global
+data in the @samp{.sdata} section. Put small uninitialized global
+data in the @samp{.sbss} section. Do not use register @code{r13}
to address small data however. This is the default behavior unless
other @option{-msdata} options are used.
operations. When @option{-mhard-float} is specified, the compiler
generates IEEE floating-point instructions. This is the default.
+@item -mlong-double-64
+@itemx -mlong-double-128
+@opindex mlong-double-64
+@opindex mlong-double-128
+These switches control the size of @code{long double} type. A size
+of 64bit makes the @code{long double} type equivalent to the @code{double}
+type. This is the default.
+
@item -mbackchain
@itemx -mno-backchain
@opindex mbackchain
if the stack size is @var{stack-guard} bytes above the @var{stack-size}
(remember that the stack on s390 grows downward). These options are intended to
be used to help debugging stack overflow problems. The additionally emitted code
-cause only little overhead and hence can also be used in production like systems
+causes only little overhead and hence can also be used in production like systems
without greater performance degradation. The given values have to be exact
-powers of 2 and @var{stack-size} has to be greater than @var{stack-guard}.
+powers of 2 and @var{stack-size} has to be greater than @var{stack-guard} without
+exceeding 64k.
In order to be efficient the extra code makes the assumption that the stack starts
at an address aligned to the value given by @var{stack-size}.
@end table
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{sparclet}, @samp{tsc701}, @samp{v9}, @samp{ultrasparc}, and
-@samp{ultrasparc3}.
+@samp{sparclet}, @samp{tsc701}, @samp{v9}, @samp{ultrasparc},
+@samp{ultrasparc3}, and @samp{niagara}.
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, ultrasparc3
+ v9: ultrasparc, ultrasparc3, niagara
@end smallexample
By default (unless configured otherwise), GCC generates code for the V7
architecture. This adds 64-bit integer and floating-point move instructions,
3 additional floating-point condition code registers and conditional move
instructions. With @option{-mcpu=ultrasparc}, the compiler additionally
-optimizes it for the Sun UltraSPARC I/II chips. With
+optimizes it for the Sun UltraSPARC I/II/IIi chips. With
@option{-mcpu=ultrasparc3}, the compiler additionally optimizes it for the
-Sun UltraSPARC III chip.
+Sun UltraSPARC III/III+/IIIi/IIIi+/IV/IV+ chips. With
+@option{-mcpu=niagara}, the compiler additionally optimizes it for
+Sun UltraSPARC T1 chips.
@item -mtune=@var{cpu_type}
@opindex mtune
@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}, and
-@samp{ultrasparc3}.
+@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc},
+@samp{ultrasparc3}, and @samp{niagara}.
@item -mv8plus
@itemx -mno-v8plus
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 System V Options
This option instructs the compiler to assume that signed arithmetic
overflow of addition, subtraction and multiplication wraps around
using twos-complement representation. This flag enables some optimizations
-and disables other. This option is enabled by default for the Java
+and disables others. This option is enabled by default for the Java
front-end, as required by the Java language specification.
@item -fexceptions
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
-compilation be shared data rather than private data. The distinction
-makes sense only on certain operating systems, where shared data is
-shared between processes running the same program, while private data
-exists in one copy per process.
-
@item -fno-common
@opindex fno-common
In C, allocate even uninitialized global variables in the data section of the
but not for the Sun 386i. Code generated for the IBM RS/6000 is always
position-independent.
+When this flag is set, the macros @code{__pic__} and @code{__PIC__}
+are defined to 1.
+
@item -fPIC
@opindex fPIC
If supported for the target machine, emit position-independent code,
Position-independent code requires special support, and therefore works
only on certain machines.
+When this flag is set, the macros @code{__pic__} and @code{__PIC__}
+are defined to 2.
+
@item -fpie
@itemx -fPIE
@opindex fpie
@item -fargument-alias
@itemx -fargument-noalias
@itemx -fargument-noalias-global
+@itemx -fargument-noalias-anything
@opindex fargument-alias
@opindex fargument-noalias
@opindex fargument-noalias-global
+@opindex fargument-noalias-anything
Specify the possible relationships among parameters and between
parameters and global data.
each other, but may alias global storage.@*
@option{-fargument-noalias-global} specifies that arguments do not
alias each other and do not alias global storage.
+@option{-fargument-noalias-anything} specifies that arguments do not
+alias any other storage.
Each language will automatically use whatever option is required by
the language standard. You should not need to use these options yourself.
An overview of these techniques, their benefits and how to use them
is at @w{@uref{http://gcc.gnu.org/wiki/Visibility}}.
+@item -fopenmp
+@opindex fopenmp
+@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
+Program Interface v2.5 @w{@uref{http://www.openmp.org/}}.
+
@end table
@c man end
is to use exactly the same options when generating and using the
precompiled header. The following are known to be safe:
-@gccoptlist{-fpreprocessed
+@gccoptlist{-fmessage-length= -fpreprocessed
-fsched-interblock -fsched-spec -fsched-spec-load -fsched-spec-load-dangerous
--fsched-verbose=<number> -fschedule-insns
+-fsched-verbose=<number> -fschedule-insns -fvisibility=
-pedantic-errors}
@end itemize
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