@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+@c Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@xref{C Dialect Options,,Options Controlling C Dialect}.
@gccoptlist{-ansi -std=@var{standard} -aux-info @var{filename} @gol
-fno-asm -fno-builtin -fno-builtin-@var{function} @gol
--fhosted -ffreestanding -fms-extensions @gol
+-fhosted -ffreestanding -fopenmp -fms-extensions @gol
-trigraphs -no-integrated-cpp -traditional -traditional-cpp @gol
--fallow-single-precision -fcond-mismatch @gol
+-fallow-single-precision -fcond-mismatch -flax-vector-conversions @gol
-fsigned-bitfields -fsigned-char @gol
-funsigned-bitfields -funsigned-char}
@item Objective-C and Objective-C++ Language Options
@xref{Objective-C and Objective-C++ Dialect Options,,Options Controlling
Objective-C and Objective-C++ Dialects}.
-@gccoptlist{
--fconstant-string-class=@var{class-name} @gol
+@gccoptlist{-fconstant-string-class=@var{class-name} @gol
-fgnu-runtime -fnext-runtime @gol
-fno-nil-receivers @gol
-fobjc-call-cxx-cdtors @gol
@item Language Independent Options
@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-options
+-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]} @gol
+-fdiagnostics-show-option}
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @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
+-w -Wextra -Wall -Waggregate-return -Walways-true -Warray-bounds @gol
+-Wno-attributes -Wc++-compat -Wc++0x-compat -Wcast-align -Wcast-qual @gol
+-Wchar-subscripts -Wclobbered -Wcomment @gol
+-Wconversion -Wcoverage-mismatch -Wno-deprecated-declarations @gol
+-Wdisabled-optimization -Wno-div-by-zero @gol
+-Wempty-body -Wno-endif-labels @gol
-Werror -Werror-* -Werror-implicit-function-declaration @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-extra-args -Wformat-nonliteral @gol
@item C-only Warning Options
@gccoptlist{-Wbad-function-cast -Wmissing-declarations @gol
--Wmissing-prototypes -Wnested-externs -Wold-style-definition @gol
--Wstrict-prototypes -Wtraditional @gol
+-Wmissing-parameter-type -Wmissing-prototypes -Wnested-externs @gol
+-Wold-style-declaration -Wold-style-definition @gol
+-Wstrict-prototypes -Wtraditional -Wtraditional-conversion @gol
-Wdeclaration-after-statement -Wpointer-sign}
@item Debugging Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
@gccoptlist{-d@var{letters} -dumpspecs -dumpmachine -dumpversion @gol
--fdump-unnumbered -fdump-translation-unit@r{[}-@var{n}@r{]} @gol
+-fdump-noaddr -fdump-unnumbered -fdump-translation-unit@r{[}-@var{n}@r{]} @gol
-fdump-class-hierarchy@r{[}-@var{n}@r{]} @gol
-fdump-ipa-all -fdump-ipa-cgraph @gol
-fdump-tree-all @gol
-fdump-tree-storeccp@r{[}-@var{n}@r{]} @gol
-feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
-feliminate-unused-debug-symbols -femit-class-debug-always @gol
--fmem-report -fprofile-arcs @gol
+-fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-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
-fcse-skip-blocks -fcx-limited-range -fdata-sections @gol
-fdelayed-branch -fdelete-null-pointer-checks -fearly-inlining @gol
-fexpensive-optimizations -ffast-math -ffloat-store @gol
--fforce-addr -ffunction-sections @gol
+-fforce-addr -fforward-propagate -ffunction-sections @gol
-fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload @gol
-fcrossjumping -fif-conversion -fif-conversion2 @gol
-finline-functions -finline-functions-called-once @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
+-funsafe-math-optimizations -funsafe-loop-optimizations @gol
+-ffinite-math-only -fno-signed-zeros @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
-fsched2-use-superblocks @gol
-fsched2-use-traces -fsee -freschedule-modulo-scheduled-loops @gol
-fsection-anchors -fsignaling-nans -fsingle-precision-constant @gol
--fstack-protector -fstack-protector-all @gol
--fstrict-aliasing -ftracer -fthread-jumps @gol
+-fno-split-wide-types -fstack-protector -fstack-protector-all @gol
+-fstrict-aliasing -fstrict-overflow -ftracer -fthread-jumps @gol
-funroll-all-loops -funroll-loops -fpeel-loops @gol
-fsplit-ivs-in-unroller -funswitch-loops @gol
-fvariable-expansion-in-unroller @gol
@emph{Blackfin Options}
@gccoptlist{-momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer @gol
-mspecld-anomaly -mno-specld-anomaly -mcsync-anomaly -mno-csync-anomaly @gol
--mlow-64k -mno-low64k -mid-shared-library @gol
+-mlow-64k -mno-low64k -mstack-check-l1 -mid-shared-library @gol
-mno-id-shared-library -mshared-library-id=@var{n} @gol
--mlong-calls -mno-long-calls}
+-mleaf-id-shared-library -mno-leaf-id-shared-library @gol
+-msep-data -mno-sep-data -mlong-calls -mno-long-calls}
@emph{CRIS Options}
@gccoptlist{-mcpu=@var{cpu} -march=@var{cpu} -mtune=@var{cpu} @gol
-twolevel_namespace -umbrella -undefined @gol
-unexported_symbols_list -weak_reference_mismatches @gol
-whatsloaded -F -gused -gfull -mmacosx-version-min=@var{version} @gol
--mone-byte-bool}
+-mkernel -mone-byte-bool}
@emph{DEC Alpha Options}
@gccoptlist{-mno-fp-regs -msoft-float -malpha-as -mgas @gol
-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 -mssse3 -msse4a -m3dnow -mpopcnt -mabm @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
@gccoptlist{-mcpu=@var{cpu} -msim -memregs=@var{number}}
@emph{M680x0 Options}
-@gccoptlist{-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040 @gol
--m68060 -mcpu32 -m5200 -mcfv4e -m68881 -mbitfield @gol
--mc68000 -mc68020 @gol
--mnobitfield -mrtd -mshort -msoft-float -mpcrel @gol
+@gccoptlist{-march=@var{arch} -mcpu=@var{cpu} -mtune=@var{tune}
+-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040 @gol
+-m68060 -mcpu32 -m5200 -m5206e -m528x -m5307 -m5407 @gol
+-mcfv4e -mbitfield -mno-bitfield -mc68000 -mc68020 @gol
+-mnobitfield -mrtd -mno-rtd -mdiv -mno-div -mshort @gol
+-mno-short -mhard-float -m68881 -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}
-mpowerpc-gpopt -mno-powerpc-gpopt @gol
-mpowerpc-gfxopt -mno-powerpc-gfxopt @gol
-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mfprnd -mno-fprnd @gol
+-mmfpgpr -mno-mfpgpr @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
-mtpf-trace -mno-tpf-trace -mfused-madd -mno-fused-madd @gol
-mwarn-framesize -mwarn-dynamicstack -mstack-size -mstack-guard}
+@emph{Score Options}
+@gccoptlist{-mel -mel @gol
+-mmac @gol
+-mscore5u -mscore7}
+
@emph{SH Options}
@gccoptlist{-m1 -m2 -m2e -m3 -m3e @gol
-m4-nofpu -m4-single-only -m4-single -m4 @gol
-m5-compact -m5-compact-nofpu @gol
-mb -ml -mdalign -mrelax @gol
-mbigtable -mfmovd -mhitachi -mrenesas -mno-renesas -mnomacsave @gol
--mieee -misize -mpadstruct -mspace @gol
+-mieee -misize -minline-ic_invalidate -mpadstruct -mspace @gol
-mprefergot -musermode -multcost=@var{number} -mdiv=@var{strategy} @gol
-mdivsi3_libfunc=@var{name} @gol
-madjust-unroll -mindexed-addressing -mgettrcost=@var{number} -mpt-fixed @gol
-mv8plus -mno-v8plus -mvis -mno-vis
-threads -pthreads -pthread}
+@emph{SPU Options}
+@gccoptlist{-mwarn-reloc -merror-reloc @gol
+-msafe-dma -munsafe-dma @gol
+-mbranch-hints @gol
+-msmall-mem -mlarge-mem -mstdmain @gol
+-mfixed-range=@var{register-range}}
+
@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
+-frecord-gcc-switches @gol
-freg-struct-return -fshort-enums @gol
-fshort-double -fshort-wchar @gol
-fverbose-asm -fpack-struct[=@var{n}] -fstack-check @gol
-fargument-noalias-global -fargument-noalias-anything
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
--fvisibility -fopenmp}
+-fvisibility}
@end table
@menu
objective-c++ objective-c++-header objective-c++-cpp-output
assembler assembler-with-cpp
ada
-f77 f77-cpp-input
f95 f95-cpp-input
java
treelang
@findex g++
@findex c++
-However, C++ programs often require class libraries as well as a
-compiler that understands the C++ language---and under some
-circumstances, you might want to compile programs or header files from
-standard input, or otherwise without a suffix that flags them as C++
-programs. You might also like to precompile a C header file with a
-@samp{.h} extension to be used in C++ compilations. @command{g++} is a
-program that calls GCC with the default language set to C++, and
-automatically specifies linking against the C++ library. On many
-systems, @command{g++} is also installed with the name @command{c++}.
+However, the use of @command{gcc} does not add the C++ library.
+@command{g++} is a program that calls GCC and treats @samp{.c},
+@samp{.h} and @samp{.i} files as C++ source files instead of C source
+files unless @option{-x} is used, and automatically specifies linking
+against the C++ library. This program is also useful when
+precompiling a C header file with a @samp{.h} extension for use in C++
+compilations. On many systems, @command{g++} is also installed with
+the name @command{c++}.
@cindex invoking @command{g++}
When you compile C++ programs, you may specify many of the same
@item gnu++98
The same as @option{-std=c++98} plus GNU extensions. This is the
default for C++ code.
+
+@item c++0x
+The working draft of the upcoming ISO C++0x standard. This option
+enables experimental features that are likely to be included in
+C++0x. The working draft is constantly changing, and any feature that is
+enabled by this flag may be removed from future versions of GCC if it is
+not part of the C++0x standard.
+
+@item gnu++0x
+The same as @option{-std=c++0x} plus GNU extensions. As with
+@option{-std=c++0x}, this option enables experimental features that may
+be removed in future versions of GCC.
@end table
Even when this option is not specified, you can still use some of the
@xref{Standards,,Language Standards Supported by GCC}, for details of
freestanding and hosted environments.
+@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/}}.
+
@item -fms-extensions
@opindex fms-extensions
Accept some non-standard constructs used in Microsoft header files.
third arguments. The value of such an expression is void. This option
is not supported for C++.
+@item -flax-vector-conversions
+@opindex flax-vector-conversions
+Allow implicit conversions between vectors with differing numbers of
+elements and/or incompatible element types. This option should not be
+used for new code.
+
@item -funsigned-char
@opindex funsigned-char
Let the type @code{char} be unsigned, like @code{unsigned char}.
(@samp{dynamic_cast} and @samp{typeid}). If you don't use those parts
of the language, you can save some space by using this flag. Note that
exception handling uses the same information, but it will generate it as
-needed.
+needed. The @samp{dynamic_cast} operator can still be used for casts that
+do not require runtime type information, i.e. casts to @code{void *} or to
+unambiguous base classes.
@item -fstats
@opindex fstats
on load and link times of a DSO as it massively reduces the size of the
dynamic export table when the library makes heavy use of templates.
-The behaviour of this switch is not quite the same as marking the
-methods as hidden directly. Normally if there is a class with default
-visibility which has a hidden method, the effect of this is that the
-method must be defined in only one shared object. This switch does
-not have this restriction.
+The behavior of this switch is not quite the same as marking the
+methods as hidden directly, because it does not affect static variables
+local to the function or cause the compiler to deduce that
+the function is defined in only one shared object.
You may mark a method as having a visibility explicitly to negate the
effect of the switch for that method. For example, if you do want to
compare pointers to a particular inline method, you might mark it as
-having default visibility.
+having default visibility. Marking the enclosing class with explicit
+visibility will have no effect.
+
+Explicitly instantiated inline methods are unaffected by this option
+as their linkage might otherwise cross a shared library boundary.
+@xref{Template Instantiation}.
@item -fno-weak
@opindex fno-weak
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-options
-@opindex fdiagnostics-show-options
+@item -fdiagnostics-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.
+@item -Wcoverage-mismatch
+@opindex Wcoverage-mismatch
+Warn if feedback profiles do not match when using the
+@option{-fprofile-use} option.
+If a source file was changed between @option{-fprofile-gen} and
+@option{-fprofile-use}, the files with the profile feedback can fail
+to match the source file and GCC can not use the profile feedback
+information. By default, GCC emits an error message in this case.
+The option @option{-Wcoverage-mismatch} emits a warning instead of an
+error. GCC does not use appropriate feedback profiles, so using this
+option can result in poorly optimized code. This option is useful
+only in the case of very minor changes such as bug fixes to an
+existing code-base.
+
@end table
@node Warning Options
Warn if parentheses are omitted in certain contexts, such
as when there is an assignment in a context where a truth value
is expected, or when operators are nested whose precedence people
-often get confused about. Only the warning for an assignment used as
-a truth value is supported when compiling C++; the other warnings are
-only supported when compiling C@.
+often get confused about.
Also warn if a comparison like @samp{x<=y<=z} appears; this is
equivalent to @samp{(x<=y ? 1 : 0) <= z}, which is a different
@end group
@end smallexample
-In C, every @code{else} branch belongs to the innermost possible @code{if}
-statement, which in this example is @code{if (b)}. This is often not
-what the programmer expected, as illustrated in the above example by
-indentation the programmer chose. When there is the potential for this
-confusion, GCC will issue a warning when this flag is specified.
-To eliminate the warning, add explicit braces around the innermost
-@code{if} statement so there is no way the @code{else} could belong to
-the enclosing @code{if}. The resulting code would look like this:
+In C/C++, every @code{else} branch belongs to the innermost possible
+@code{if} statement, which in this example is @code{if (b)}. This is
+often not what the programmer expected, as illustrated in the above
+example by indentation the programmer chose. When there is the
+potential for this confusion, GCC will issue a warning when this flag
+is specified. To eliminate the warning, add explicit braces around
+the innermost @code{if} statement so there is no way the @code{else}
+could belong to the enclosing @code{if}. The resulting code would
+look like this:
@smallexample
@group
@code{int}. Also warn about any @code{return} statement with no
return-value in a function whose return-type is not @code{void}.
-For C, also warn if the return type of a function has a type qualifier
-such as @code{const}. Such a type qualifier has no effect, since the
-value returned by a function is not an lvalue. ISO C prohibits
-qualified @code{void} return types on function definitions, so such
-return types always receive a warning even without this option.
+Also warn if the return type of a function has a type qualifier
+such as @code{const}. For ISO C such a type qualifier has no effect,
+since the value returned by a function is not an lvalue.
+For C++, the warning is only emitted for scalar types or @code{void}.
+ISO C prohibits qualified @code{void} return types on function
+definitions, so such return types always receive a warning
+even without this option.
For C++, a function without return type always produces a diagnostic
message, even when @option{-Wno-return-type} is specified. The only
@item -Wunused-variable
@opindex Wunused-variable
Warn whenever a local variable or non-constant static variable is unused
-aside from its declaration
+aside from its declaration.
This warning is enabled by @option{-Wall}.
To suppress this warning use the @samp{unused} attribute
@option{-Wstrict-aliasing}, but it will also give a warning for some ambiguous
cases that are safe.
+@item -Warray-bounds
+@opindex Wno-array-bounds
+@opindex Warray-bounds
+This option is only active when @option{-ftree-vrp} is active
+(default for -O2 and above). It warns about subscripts to arrays
+that are always out of bounds. This warning is enabled by @option{-Wall}.
+
@item -Wall
@opindex Wall
All of the above @samp{-W} options combined. This enables all the
@item
An unsigned value is compared against zero with @samp{<} or @samp{>=}.
-@item
-Storage-class specifiers like @code{static} are not the first things in
-a declaration. According to the C Standard, this usage is obsolescent.
+@item @r{(C only)}
+Storage-class specifiers like @code{static} are not the first things
+in a declaration. According to the C Standard, this usage is
+obsolescent. This warning can be independently controlled by
+@option{-Wold-style-declaration}.
@item
If @option{-Wall} or @option{-Wunused} is also specified, warn about unused
@option{-Wmissing-field-initializers}.
@item
-A function parameter is declared without a type specifier in K&R-style
-functions:
+An initialized field without side effects is overridden when using
+designated initializers (@pxref{Designated Inits, , Designated
+Initializers}). This warning can be independently controlled by
+@option{-Woverride-init}.
-@smallexample
-void foo(bar) @{ @}
-@end smallexample
+@item @r{(C only)}
+A function parameter is declared without a type specifier in K&R-style
+functions. This warning can be independently controlled by
+@option{-Wmissing-parameter-type}.
@item
-An empty body occurs in an @samp{if} or @samp{else} statement.
+An empty body occurs in an @samp{if} or @samp{else} statement. This
+warning can be independently controlled by @option{-Wempty-body}.
@item
A pointer is compared against integer zero with @samp{<}, @samp{<=},
@item
A variable might be changed by @samp{longjmp} or @samp{vfork}.
-
-@item
-Any of several floating-point events that often indicate errors, such as
-overflow, underflow, loss of precision, etc.
+This warning can be independently controlled by @option{-Wclobbered}.
@item @r{(C++ only)}
An enumerator and a non-enumerator both appear in a conditional expression.
Conversions by prototypes between fixed/floating point values and vice
versa. The absence of these prototypes when compiling with traditional
C would cause serious problems. This is a subset of the possible
-conversion warnings, for the full set use @option{-Wconversion}.
+conversion warnings, for the full set use @option{-Wtraditional-conversion}.
@item
Use of ISO C style function definitions. This warning intentionally is
traditional C compatibility.
@end itemize
+@item -Wtraditional-conversion @r{(C only)}
+@opindex Wtraditional-conversion
+Warn if a prototype causes a type conversion that is different from what
+would happen to the same argument in the absence of a prototype. This
+includes conversions of fixed point to floating and vice versa, and
+conversions changing the width or signedness of a fixed point argument
+except when the same as the default promotion.
+
@item -Wdeclaration-after-statement @r{(C only)}
@opindex Wdeclaration-after-statement
Warn when a declaration is found after a statement in a block. This
Warn about anything that depends on the ``size of'' a function type or
of @code{void}. GNU C assigns these types a size of 1, for
convenience in calculations with @code{void *} pointers and pointers
-to functions.
+to functions. In C++, warn also when an arithmetic operation involves
+@code{NULL}. This warning is also enabled by @option{-pedantic}.
@item -Wbad-function-cast @r{(C only)}
@opindex Wbad-function-cast
ISO C and ISO C++, e.g.@: request for implicit conversion from
@code{void *} to a pointer to non-@code{void} type.
+@item -Wc++0x-compat @r{(C++ and Objective-C++ only)}
+Warn about C++ constructs whose meaning differs between ISO C++ 1998 and
+ISO C++ 200x, e.g., identifiers in ISO C++ 1998 that will become keywords
+in ISO C++ 200x. This warning is enabled by @option{-Wall}.
+
@item -Wcast-qual
@opindex Wcast-qual
Warn whenever a pointer is cast so as to remove a type qualifier from
declarations and prototypes. Otherwise, it will just be a nuisance;
this is why we did not make @option{-Wall} request these warnings.
+@item -Wclobbered
+@opindex Wclobbered
+Warn for variables that might be changed by @samp{longjmp} or
+@samp{vfork}. This warning is also enabled by @option{-Wextra}.
+
@item -Wconversion
@opindex Wconversion
-Warn if a prototype causes a type conversion that is different from what
-would happen to the same argument in the absence of a prototype. This
-includes conversions of fixed point to floating and vice versa, and
-conversions changing the width or signedness of a fixed point argument
-except when the same as the default promotion.
-
-Also, warn if a negative integer constant expression is implicitly
-converted to an unsigned type. For example, warn about the assignment
-@code{x = -1} if @code{x} is unsigned. But do not warn about explicit
-casts like @code{(unsigned) -1}.
+Warn for implicit conversions that may alter a value. This includes
+conversions between real and integer, like @code{abs (x)} when
+@code{x} is @code{double}; conversions between signed and unsigned,
+like @code{unsigned ui = -1}; and conversions to smaller types, like
+@code{sqrtf (M_PI)}. Do not warn for explicit casts like @code{abs
+((int) x)} and @code{ui = (unsigned) -1}, or if the value is not
+changed by the conversion like in @code{abs (2.0)}.
+
+@item -Wempty-body
+@opindex Wempty-body
+An empty body occurs in an @samp{if} or @samp{else} statement.
+This warning is also enabled by @option{-Wextra}.
@item -Wsign-compare
@opindex Wsign-compare
a warning if preceded by a declaration which specifies the argument
types.)
+@item -Wold-style-declaration @r{(C only)}
+@opindex Wold-style-declaration
+Warn for obsolescent usages, according to the C Standard, in a
+declaration. For example, warn if storage-class specifiers like
+@code{static} are not the first things in a declaration. This warning
+is also enabled by @option{-Wextra}.
+
@item -Wold-style-definition @r{(C only)}
@opindex Wold-style-definition
Warn if an old-style function definition is used. A warning is given
even if there is a previous prototype.
+@item -Wmissing-parameter-type @r{(C only)}
+@opindex Wmissing-parameter-type
+A function parameter is declared without a type specifier in K&R-style
+functions:
+
+@smallexample
+void foo(bar) @{ @}
+@end smallexample
+
+This warning is also enabled by @option{-Wextra}.
+
@item -Wmissing-prototypes @r{(C only)}
@opindex Wmissing-prototypes
Warn if a global function is defined without a previous prototype
provides a prototype. The aim is to detect global functions that fail
to be declared in header files.
-@item -Wmissing-declarations @r{(C only)}
+@item -Wmissing-declarations @r{(C and C++ only)}
@opindex Wmissing-declarations
Warn if a global function is defined without a previous declaration.
Do so even if the definition itself provides a prototype.
Use this option to detect global functions that are not declared in
-header files.
+header files. In C++, no warnings are issued for function templates,
+or for inline functions, or for functions in anonymous namespaces.
@item -Wmissing-field-initializers
@opindex Wmissing-field-initializers
been applied. For instance @code{\u207F}, ``SUPERSCRIPT LATIN SMALL
LETTER N'', will display just like a regular @code{n} which has been
placed in a superscript. ISO 10646 defines the @dfn{NFKC}
-normalisation scheme to convert all these into a standard form as
+normalization scheme to convert all these into a standard form as
well, and GCC will warn if your code is not in NFKC if you use
@option{-Wnormalized=nfkc}. This warning is comparable to warning
about every identifier that contains the letter O because it might be
@item -Wno-deprecated-declarations
@opindex Wno-deprecated-declarations
-Do not warn about uses of functions, variables, and types marked as
-deprecated by using the @code{deprecated} attribute.
-(@pxref{Function Attributes}, @pxref{Variable Attributes},
-@pxref{Type Attributes}.)
+Do not warn about uses of functions (@pxref{Function Attributes}),
+variables (@pxref{Variable Attributes}), and types (@pxref{Type
+Attributes}) marked as deprecated by using the @code{deprecated}
+attribute.
@item -Wno-overflow
@opindex Wno-overflow
Do not warn about compile-time overflow in constant expressions.
+@item -Woverride-init
+@opindex Woverride-init
+@opindex W
+@opindex Wextra
+Warn if an initialized field without side effects is overridden when
+using designated initializers (@pxref{Designated Inits, , Designated
+Initializers}).
+
+This warning is included in @option{-Wextra}. To get other
+@option{-Wextra} warnings without this one, use @samp{-Wextra
+-Wno-override-init}.
+
@item -Wpacked
@opindex Wpacked
Warn if a structure is given the packed attribute, but the packed
Request debugging information and also use @var{level} to specify how
much information. The default level is 2.
+Level 0 produces no debug information at all. Thus, @option{-g0} negates
+@option{-g}.
+
Level 1 produces minimal information, enough for making backtraces in
parts of the program that you don't plan to debug. This includes
descriptions of functions and external variables, but no information
Makes the compiler print some statistics about permanent memory
allocation when it finishes.
+@item -fpre-ipa-mem-report
+@opindex fpre-ipa-mem-report
+@item -fpost-ipa-mem-report
+@opindex fpost-ipa-mem-report
+Makes the compiler print some statistics about permanent memory
+allocation before or after interprocedural optimization.
+
@item -fprofile-arcs
@opindex fprofile-arcs
Add code so that program flow @dfn{arcs} are instrumented. During
@itemx -fdump-rtl-combine
@opindex dc
@opindex fdump-rtl-combine
-Dump after instruction combination, to the file @file{@var{file}.129r.combine}.
+Dump after the RTL instruction combination pass, to the file
+@file{@var{file}.129r.combine}.
@item -dC
@itemx -fdump-rtl-ce1
@itemx -fdump-rtl-stack
@opindex dk
@opindex fdump-rtl-stack
-Dump after conversion from registers to stack, to @file{@var{file}.152r.stack}.
+Dump after conversion from GCC's "flat register file" registers to the
+x87's stack-like registers, to @file{@var{file}.152r.stack}.
@item -dl
@itemx -fdump-rtl-lreg
@itemx -fdump-rtl-sched2
@opindex dR
@opindex fdump-rtl-sched2
-Dump after the second scheduling pass, to @file{@var{file}.150r.sched2}.
+Dump after the second scheduling pass, to @file{@var{file}.149r.sched2}.
@item -ds
@itemx -fdump-rtl-cse
CSE), to @file{@var{file}.113r.cse}.
@item -dS
-@itemx -fdump-rtl-sched
+@itemx -fdump-rtl-sched1
@opindex dS
-@opindex fdump-rtl-sched
-Dump after the first scheduling pass, to @file{@var{file}.21.sched}.
+@opindex fdump-rtl-sched1
+Dump after the first scheduling pass, to @file{@var{file}.136r.sched1}.
@item -dt
@itemx -fdump-rtl-cse2
Dump debugging information during parsing, to standard error.
@end table
+@item -fdump-noaddr
+@opindex fdump-noaddr
+When doing debugging dumps (see @option{-d} option above), suppress
+address output. This makes it more feasible to use diff on debugging
+dumps for compiler invocations with different compiler binaries and/or
+different text / bss / data / heap / stack / dso start locations.
+
@item -fdump-unnumbered
@opindex fdump-unnumbered
When doing debugging dumps (see @option{-d} option above), suppress instruction
-numbers and line number note output. This makes it more feasible to
+numbers, line number note and address output. This makes it more feasible to
use diff on debugging dumps for compiler invocations with different
options, in particular with and without @option{-g}.
-fcprop-registers @gol
-fif-conversion @gol
-fif-conversion2 @gol
+-fsplit-wide-types @gol
-ftree-ccp @gol
-ftree-dce @gol
-ftree-dominator-opts @gol
-fschedule-insns -fschedule-insns2 @gol
-fsched-interblock -fsched-spec @gol
-fregmove @gol
--fstrict-aliasing @gol
+-fstrict-aliasing -fstrict-overflow @gol
-fdelete-null-pointer-checks @gol
-freorder-blocks -freorder-functions @gol
-falign-functions -falign-jumps @gol
@item -O0
@opindex O0
-Do not optimize. This is the default.
+Reduce compilation time and make debugging produce the expected
+results. This is the default.
@item -Os
@opindex Os
Disabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
-@item -fforce-mem
-@opindex fforce-mem
-Force memory operands to be copied into registers before doing
-arithmetic on them. This produces better code by making all memory
-references potential common subexpressions. When they are not common
-subexpressions, instruction combination should eliminate the separate
-register-load. This option is now a nop and will be removed in 4.2.
-
@item -fforce-addr
@opindex fforce-addr
Force memory address constants to be copied into registers before
doing arithmetic on them.
+@item -fforward-propagate
+@opindex fforward-propagate
+Perform a forward propagation pass on RTL. The pass tries to combine two
+instructions and checks if the result can be simplified. If loop unrolling
+is active, two passes are performed and the second is scheduled after
+loop unrolling.
+
+This option is enabled by default at optimization levels @option{-O2},
+@option{-O3}, @option{-Os}.
+
@item -fomit-frame-pointer
@opindex fomit-frame-pointer
Don't keep the frame pointer in a register for functions that
as follows:
@table @gcctabopt
- @item max-inline-insns-single
- is set to @var{n}/2.
- @item max-inline-insns-auto
- is set to @var{n}/2.
- @item min-inline-insns
- is set to 130 or @var{n}/4, whichever is smaller.
- @item max-inline-insns-rtl
- is set to @var{n}.
+@item max-inline-insns-single
+ is set to @var{n}/2.
+@item max-inline-insns-auto
+ is set to @var{n}/2.
+@item min-inline-insns
+ is set to 130 or @var{n}/4, whichever is smaller.
+@item max-inline-insns-rtl
+ is set to @var{n}.
@end table
See below for a documentation of the individual
In C, emit @code{static} functions that are declared @code{inline}
into the object file, even if the function has been inlined into all
of its callers. This switch does not affect functions using the
-@code{extern inline} extension in GNU C@. In C++, emit any and all
+@code{extern inline} extension in GNU C89@. In C++, emit any and all
inline functions into the object file.
@item -fkeep-static-consts
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fsplit-wide-types
+@opindex -fsplit-wide-types
+When using a type that occupies multiple registers, such as @code{long
+long} on a 32-bit system, split the registers apart and allocate them
+independently. This normally generates better code for those types,
+but may make debugging more difficult.
+
+Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
+@option{-Os}.
+
@item -fcse-follow-jumps
@opindex fcse-follow-jumps
In common subexpression elimination, scan through jump instructions
@}
@end smallexample
-Every language that wishes to perform language-specific alias analysis
-should define a function that computes, given an @code{tree}
-node, an alias set for the node. Nodes in different alias sets are not
-allowed to alias. For an example, see the C front-end function
-@code{c_get_alias_set}.
-
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fstrict-overflow
+@opindex fstrict-overflow
+Allow the compiler to assume strict signed overflow rules, depending
+on the language being compiled. For C (and C++) this means that
+overflow when doing arithmetic with signed numbers is undefined, which
+means that the compiler may assume that it will not happen. This
+permits various optimizations. For example, the compiler will assume
+that an expression like @code{i + 10 > i} will always be true for
+signed @code{i}. This assumption is only valid if signed overflow is
+undefined, as the expression is false if @code{i + 10} overflows when
+using twos complement arithmetic. When this option is in effect any
+attempt to determine whether an operation on signed numbers will
+overflow must be written carefully to not actually involve overflow.
+
+See also the @option{-fwrapv} option. Using @option{-fwrapv} means
+that signed overflow is fully defined: it wraps. When
+@option{-fwrapv} is used, there is no difference between
+@option{-fstrict-overflow} and @option{-fno-strict-overflow}. With
+@option{-fwrapv} certain types of overflow are permitted. For
+example, if the compiler gets an overflow when doing arithmetic on
+constants, the overflowed value can still be used with
+@option{-fwrapv}, but not otherwise.
+
+The @option{-fstrict-overflow} option is enabled at levels
+@option{-O2}, @option{-O3}, @option{-Os}.
+
@item -falign-functions
@itemx -falign-functions=@var{n}
@opindex falign-functions
The following options are enabled: @code{-fbranch-probabilities}, @code{-fvpt},
@code{-funroll-loops}, @code{-fpeel-loops}, @code{-ftracer}
+By default, GCC emits an error message if the feedback profiles do not
+match the source code. This error can be turned into a warning by using
+@option{-Wcoverage-mismatch}. Note this may result in poorly optimized
+code.
@end table
The following options control compiler behavior regarding floating
@opindex ffast-math
Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @*
@option{-fno-trapping-math}, @option{-ffinite-math-only},
-@option{-fno-rounding-math}, @option{-fno-signaling-nans}
-and @option{fcx-limited-range}.
+@option{-fno-rounding-math}, @option{-fno-signaling-nans},
+@option{-fno-signed-zeros} and @option{fcx-limited-range}.
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
The default is @option{-fmath-errno}.
-On Darwin systems, the math library never sets @code{errno}. There is therefore
-no reason for the compiler to consider the possibility that it might,
-and @option{-fno-math-errno} is the default.
+On Darwin systems, the math library never sets @code{errno}. There is
+therefore no reason for the compiler to consider the possibility that
+it might, and @option{-fno-math-errno} is the default.
@item -funsafe-math-optimizations
@opindex funsafe-math-optimizations
The default is @option{-fno-finite-math-only}.
+@item -fno-signed-zeros
+@opindex fno-signed-zeros
+Allow optimizations for floating point arithmetic that ignore the
+signedness of zero. IEEE arithmetic specifies the behavior of
+distinct +0.0 and @minus{}0.0 values, which then prohibits simplification
+of expressions such as x+0.0 or 0.0*x (even with @option{-ffinite-math-only}).
+This option implies that the sign of a zero result isn't significant.
+
+The default is @option{-fsigned-zeros}.
+
@item -fno-trapping-math
@opindex fno-trapping-math
Compile code assuming that floating-point operations cannot generate
the number of times each branch was taken. When the program
compiled with @option{-fprofile-arcs} exits it saves arc execution
counts to a file called @file{@var{sourcename}.gcda} for each source
-file The information in this data file is very dependent on the
+file. The information in this data file is very dependent on the
structure of the generated code, so you must use the same source code
and the same optimization options for both compilations.
@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.
-The default value is 50 which limits unit growth to 1.5 times the original
+The default value is 30 which limits unit growth to 1.3 times the original
size.
+@item large-stack-frame
+The limit specifying large stack frames. While inlining the algorithm is trying
+to not grow past this limit too much. Default value is 256 bytes.
+
+@item large-stack-frame-growth
+Specifies maximal growth of large stack frames caused by inlining in percents.
+The default value is 1000 which limits large stack frame growth to 11 times
+the original size.
+
@item max-inline-insns-recursive
@itemx max-inline-insns-recursive-auto
Specifies maximum number of instructions out-of-line copy of self recursive inline
function can grow into by performing recursive inlining.
For functions declared inline @option{--param max-inline-insns-recursive} is
-taken into acount. For function not declared inline, recursive inlining
+taken into account. For function not declared inline, recursive inlining
happens only when @option{-finline-functions} (included in @option{-O3}) is
enabled and @option{--param max-inline-insns-recursive-auto} is used. The
default value is 450.
Specifies maximum recursion depth used by the recursive inlining.
For functions declared inline @option{--param max-inline-recursive-depth} is
-taken into acount. For function not declared inline, recursive inlining
+taken into account. For function not declared inline, recursive inlining
happens only when @option{-finline-functions} (included in @option{-O3}) is
enabled and @option{--param max-inline-recursive-depth-auto} is used. The
default value is 450.
pass the arguments to other functions) and decrease inlining for code with low
abstraction penalty. The default value is 16.
+@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
+vectorization needs to be greater than the value specified by this option
+to allow vectorization. The default value is 0.
+
@item max-unrolled-insns
The maximum number of instructions that a loop should have if that loop
is unrolled, and if the loop is unrolled, it determines how many times
@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
-call-clobbered variables (@var{v}). If @var{n}x@var{v} is larger than this limit, a
-single artificial variable will be created to represent all the
-call-clobbered variables at function call sites. This artificial
-variable will then be made to alias every call-clobbered variable.
-(done as @code{int * size_t} on the host machine; beware overflow).
-
@item max-aliased-vops
-Maximum number of virtual operands allowed to represent aliases
-before triggering the alias grouping heuristic. Alias grouping
-reduces compile times and memory consumption needed for aliasing at
-the expense of precision loss in alias information.
+Maximum number of virtual operands per statement allowed to represent
+aliases before triggering the alias grouping heuristic. Alias
+grouping reduces compile times and memory consumption needed for
+aliasing at the expense of precision loss in alias information.
@item ggc-min-expand
compile time increase with probably slightly better performance. The default
value is 100.
-@item max-cselib-memory-location
-The maximum number of memory locations cselib should take into acount.
+@item max-cselib-memory-locations
+The maximum number of memory locations cselib should take into account.
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.
+@item max-flow-memory-locations
+Similar as @option{max-cselib-memory-locations} but for dataflow liveness.
The default value is 100.
@item reorder-blocks-duplicate
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.
+The default value is 0.
@item max-sched-insn-conflict-delay
The maximum conflict delay for an insn to be considered for speculative motion.
Maximum number of fields in a structure we will treat in
a field sensitive manner during pointer analysis.
+@item prefetch-latency
+Estimate on average number of instructions that are executed before
+prefetch finishes. The distance we prefetch ahead is proportional
+to this constant. Increasing this number may also lead to less
+streams being prefetched (see @option{simultaneous-prefetches}).
+
+@item simultaneous-prefetches
+Maximum number of prefetches that can run at the same time.
+
+@item l1-cache-line-size
+The size of cache line in L1 cache, in bytes.
+
+@item l1-cache-size
+The number of cache lines in L1 cache.
+
+@item verify-canonical-types
+Whether the compiler should verify the ``canonical'' types used for
+type equality comparisons within the C++ and Objective-C++ front
+ends. Set to 1 (the default when GCC is configured with
+--enable-checking) to enable verification, 0 to disable verification
+(the default when GCC is configured with --disable-checking).
+
@end table
@end table
* PowerPC Options::
* RS/6000 and PowerPC Options::
* S/390 and zSeries Options::
+* Score Options::
* SH Options::
* SPARC Options::
+* SPU Options::
* System V Options::
* TMS320C3x/C4x Options::
* V850 Options::
@samp{arm10tdmi}, @samp{arm1020t}, @samp{arm1026ej-s},
@samp{arm10e}, @samp{arm1020e}, @samp{arm1022e},
@samp{arm1136j-s}, @samp{arm1136jf-s}, @samp{mpcore}, @samp{mpcorenovfp},
-@samp{arm1176jz-s}, @samp{arm1176jzf-s}, @samp{xscale}, @samp{iwmmxt},
-@samp{ep9312}.
+@samp{arm1156t2-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
+@samp{cortex-a8}, @samp{cortex-r4}, @samp{cortex-m3},
+@samp{xscale}, @samp{iwmmxt}, @samp{ep9312}.
@itemx -mtune=@var{name}
@opindex mtune
of the @option{-mcpu=} option. Permissible names are: @samp{armv2},
@samp{armv2a}, @samp{armv3}, @samp{armv3m}, @samp{armv4}, @samp{armv4t},
@samp{armv5}, @samp{armv5t}, @samp{armv5te}, @samp{armv6}, @samp{armv6j},
-@samp{iwmmxt}, @samp{ep9312}.
+@samp{armv6t2}, @samp{armv6z}, @samp{armv6zk}, @samp{armv7}, @samp{armv7-a},
+@samp{armv7-r}, @samp{armv7-m}, @samp{iwmmxt}, @samp{ep9312}.
@item -mfpu=@var{name}
@itemx -mfpe=@var{number}
@item -mthumb
@opindex mthumb
-Generate code for the 16-bit Thumb instruction set. The default is to
+Generate code for the Thumb instruction set. The default is to
use the 32-bit ARM instruction set.
+This option automatically enables either 16-bit Thumb-1 or
+mixed 16/32-bit Thumb-2 instructions based on the @option{-mcpu=@var{name}}
+and @option{-march=@var{name}} options.
@item -mtpcs-frame
@opindex mtpcs-frame
@opindex mno-low-64k
Assume that the program is arbitrarily large. This is the default.
+@item -mstack-check-l1
+@opindex mstack-check-l1
+Do stack checking using information placed into L1 scratchpad memory by the
+uClinux kernel.
+
@item -mid-shared-library
@opindex mid-shared-library
Generate code that supports shared libraries via the library ID method.
Generate code that doesn't assume ID based shared libraries are being used.
This is the default.
+@item -mleaf-id-shared-library
+@opindex mleaf-id-shared-library
+Generate code that supports shared libraries via the library ID method,
+but assumes that this library or executable won't link against any other
+ID shared libraries. That allows the compiler to use faster code for jumps
+and calls.
+
+@item -mno-leaf-id-shared-library
+@opindex mno-leaf-id-shared-library
+Do not assume that the code being compiled won't link against any ID shared
+libraries. Slower code will be generated for jump and call insns.
+
@item -mshared-library-id=n
@opindex mshared-library-id
Specified the identification number of the ID based shared library being
other values will force the allocation of that number to the current
library but is no more space or time efficient than omitting this option.
+@item -msep-data
+@opindex msep-data
+Generate code that allows the data segment to be located in a different
+area of memory from the text segment. This allows for execute in place in
+an environment without virtual memory management by eliminating relocations
+against the text section.
+
+@item -mno-sep-data
+@opindex mno-sep-data
+Generate code that assumes that the data segment follows the text segment.
+This is the default.
+
@item -mlong-calls
@itemx -mno-long-calls
@opindex mlong-calls
The default for this option is to make choices that seem to be most
useful.
+@item -mkernel
+@opindex mkernel
+Enable kernel development mode. The @option{-mkernel} option sets
+@option{-static}, @option{-fno-common}, @option{-fno-cxa-atexit},
+@option{-fno-exceptions}, @option{-fno-non-call-exceptions},
+@option{-fapple-kext}, @option{-fno-weak} and @option{-fno-rtti} where
+applicable. This mode also sets @option{-mno-altivec},
+@option{-msoft-float}, @option{-fno-builtin} and
+@option{-mlong-branch} for PowerPC targets.
+
@item -mone-byte-bool
@opindex -mone-byte-bool
Override the defaults for @samp{bool} so that @samp{sizeof(bool)==1}.
as well.
@item su
-Like @samp{su}, but the instructions are marked to be safe for software
+Like @samp{u}, but the instructions are marked to be safe for software
completion (see Alpha architecture manual for details).
@item sui
@item nocona
Improved version of Intel Pentium4 CPU with 64-bit extensions, MMX, SSE,
SSE2 and SSE3 instruction set support.
+@item core2
+Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
+instruction set support.
@item k6
AMD K6 CPU with MMX instruction set support.
@item k6-2, k6-3
@item k8, opteron, athlon64, athlon-fx
AMD K8 core based CPUs with x86-64 instruction set support. (This supersets
MMX, SSE, SSE2, 3dNOW!, enhanced 3dNOW! and 64-bit instruction set extensions.)
+@item amdfam10
+AMD Family 10 core based CPUs with x86-64 instruction set support. (This
+supersets MMX, SSE, SSE2, SSE3, SSE4A, 3dNOW!, enhanced 3dNOW!, ABM and 64-bit
+instruction set extensions.)
@item winchip-c6
IDT Winchip C6 CPU, dealt in same way as i486 with additional MMX instruction
set support.
@item c3-2
Via C3-2 CPU with MMX and SSE instruction set support. (No scheduling is
implemented for this chip.)
+@item geode
+Embedded AMD CPU with MMX and 3dNOW! instruction set support.
@end table
While picking a specific @var{cpu-type} will schedule things appropriately
produce code that runs somewhat faster on a @samp{Pentium} at the
expense of more memory.
+On x86-64, @option{-malign-double} is enabled by default.
+
@strong{Warning:} if you use the @option{-malign-double} switch,
structures containing the above types will be aligned differently than
the published application binary interface specifications for the 386
@opindex mpreferred-stack-boundary
Attempt to keep the stack boundary aligned to a 2 raised to @var{num}
byte boundary. If @option{-mpreferred-stack-boundary} is not specified,
-the default is 4 (16 bytes or 128 bits), except when optimizing for code
-size (@option{-Os}), in which case the default is the minimum correct
-alignment (4 bytes for x86, and 8 bytes for x86-64).
+the default is 4 (16 bytes or 128 bits).
On Pentium and PentiumPro, @code{double} and @code{long double} values
should be aligned to an 8 byte boundary (see @option{-malign-double}) or
suffer significant run time performance penalties. On Pentium III, the
-Streaming SIMD Extension (SSE) data type @code{__m128} suffers similar
-penalties if it is not 16 byte aligned.
+Streaming SIMD Extension (SSE) data type @code{__m128} may not work
+properly if it is not 16 byte aligned.
To ensure proper alignment of this values on the stack, the stack boundary
must be as aligned as that required by any value stored on the stack.
@itemx -mno-sse2
@item -msse3
@itemx -mno-sse3
+@item -mssse3
+@itemx -mno-ssse3
+@item -msse4a
+@item -mno-sse4a
@item -m3dnow
@itemx -mno-3dnow
+@item -mpopcnt
+@itemx -mno-popcnt
+@item -mabm
+@itemx -mno-abm
@opindex mmmx
@opindex mno-mmx
@opindex msse
@opindex m3dnow
@opindex mno-3dnow
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.
+SSE, SSE2, SSE3, SSSE3, SSE4A, ABM 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 (as opposed to 387 instructions), see @option{-mfpmath=sse}.
size, but may improve performance of code that depends on fast memcpy, strlen
and memset for short lengths.
+@item -minline-stringops-dynamically
+@opindex minline-stringops-dynamically
+For string operation of unknown size, inline runtime checks so for small
+blocks inline code is used, while for large blocks library call is used.
+
+@item -mstringop-strategy=@var{alg}
+@opindex mstringop-strategy=@var{alg}
+Overwrite internal decision heuristic about particular algorithm to inline
+string operation with. The allowed values are @code{rep_byte},
+@code{rep_4byte}, @code{rep_8byte} for expanding using i386 @code{rep} prefix
+of specified size, @code{byte_loop}, @code{loop}, @code{unrolled_loop} for
+expanding inline loop, @code{libcall} for always expanding library call.
+
@item -momit-leaf-frame-pointer
@opindex momit-leaf-frame-pointer
Don't keep the frame pointer in a register for leaf functions. This
@subsection M680x0 Options
@cindex M680x0 options
-These are the @samp{-m} options defined for the 68000 series. The default
-values for these options depends on which style of 68000 was selected when
-the compiler was configured; the defaults for the most common choices are
-given below.
+These are the @samp{-m} options defined for M680x0 and ColdFire processors.
+The default settings depend on which architecture was selected when
+the compiler was configured; the defaults for the most common choices
+are given below.
@table @gcctabopt
+@item -march=@var{arch}
+@opindex march
+Generate code for a specific M680x0 or ColdFire instruction set
+architecture. Permissible values of @var{arch} for M680x0
+architectures are: @samp{68000}, @samp{68010}, @samp{68020},
+@samp{68030}, @samp{68040}, @samp{68060} and @samp{cpu32}. ColdFire
+architectures are selected according to Freescale's ISA classification
+and the permissible values are: @samp{isaa}, @samp{isaaplus},
+@samp{isab} and @samp{isac}.
+
+gcc defines a macro @samp{__mcf@var{arch}__} whenever it is generating
+code for a ColdFire target. The @var{arch} in this macro is one of the
+@option{-march} arguments given above.
+
+When used together, @option{-march} and @option{-mtune} select code
+that runs on a family of similar processors but that is optimized
+for a particular microarchitecture.
+
+@item -mcpu=@var{cpu}
+@opindex mcpu
+Generate code for a specific M680x0 or ColdFire processor.
+The M680x0 @var{cpu}s are: @samp{68000}, @samp{68010}, @samp{68020},
+@samp{68030}, @samp{68040}, @samp{68060}, @samp{68302}, @samp{68332}
+and @samp{cpu32}. The ColdFire @var{cpu}s are given by the table
+below, which also classifies the CPUs into families:
+
+@multitable @columnfractions 0.20 0.80
+@item @strong{Family} @tab @strong{@samp{-mcpu} arguments}
+@item @samp{5206} @tab @samp{5202} @samp{5204} @samp{5206}
+@item @samp{5206e} @tab @samp{5206e}
+@item @samp{5208} @tab @samp{5207} @samp{5208}
+@item @samp{5211a} @tab @samp{5210a} @samp{5211a}
+@item @samp{5213} @tab @samp{5211} @samp{5212} @samp{5213}
+@item @samp{5216} @tab @samp{5214} @samp{5216}
+@item @samp{52235} @tab @samp{52230} @samp{52231} @samp{52232} @samp{52233} @samp{52234} @samp{52235}
+@item @samp{5225} @tab @samp{5224} @samp{5225}
+@item @samp{5235} @tab @samp{5232} @samp{5233} @samp{5234} @samp{5235} @samp{523x}
+@item @samp{5249} @tab @samp{5249}
+@item @samp{5250} @tab @samp{5250}
+@item @samp{5271} @tab @samp{5270} @samp{5271}
+@item @samp{5272} @tab @samp{5272}
+@item @samp{5275} @tab @samp{5274} @samp{5275}
+@item @samp{5282} @tab @samp{5280} @samp{5281} @samp{5282} @samp{528x}
+@item @samp{5307} @tab @samp{5307}
+@item @samp{5329} @tab @samp{5327} @samp{5328} @samp{5329} @samp{532x}
+@item @samp{5373} @tab @samp{5372} @samp{5373} @samp{537x}
+@item @samp{5407} @tab @samp{5407}
+@item @samp{5475} @tab @samp{5470} @samp{5471} @samp{5472} @samp{5473} @samp{5474} @samp{5475} @samp{547x} @samp{5480} @samp{5481} @samp{5482} @samp{5483} @samp{5484} @samp{5485}
+@end multitable
+
+@option{-mcpu=@var{cpu}} overrides @option{-march=@var{arch}} if
+@var{arch} is compatible with @var{cpu}. Other combinations of
+@option{-mcpu} and @option{-march} are rejected.
+
+gcc defines the macro @samp{__mcf_cpu_@var{cpu}} when ColdFire target
+@var{cpu} is selected. It also defines @samp{__mcf_family_@var{family}},
+where the value of @var{family} is given by the table above.
+
+@item -mtune=@var{tune}
+@opindex mtune
+Tune the code for a particular microarchitecture, within the
+constraints set by @option{-march} and @option{-mcpu}.
+The M680x0 microarchitectures are: @samp{68000}, @samp{68010},
+@samp{68020}, @samp{68030}, @samp{68040}, @samp{68060}
+and @samp{cpu32}. The ColdFire microarchitectures
+are: @samp{cfv2}, @samp{cfv3}, @samp{cfv4} and @samp{cfv4e}.
+
+You can also use @option{-mtune=68020-40} for code that needs
+to run relatively well on 68020, 68030 and 68040 targets.
+@option{-mtune=68020-60} is similar but includes 68060 targets
+as well. These two options select the same tuning decisions as
+@option{-m68020-40} and @option{-m68020-60} respectively.
+
+gcc defines the macros @samp{__mc@var{arch}} and @samp{__mc@var{arch}__}
+when tuning for 680x0 architecture @var{arch}. It also defines
+@samp{mc@var{arch}} unless either @option{-ansi} or a non-GNU @option{-std}
+option is used. If gcc is tuning for a range of architectures,
+as selected by @option{-mtune=68020-40} or @option{-mtune=68020-60},
+it defines the macros for every architecture in the range.
+
+gcc also defines the macro @samp{__m@var{uarch}__} when tuning for
+ColdFire microarchitecture @var{uarch}, where @var{uarch} is one
+of the arguments given above.
+
@item -m68000
@itemx -mc68000
@opindex m68000
@opindex mc68000
Generate output for a 68000. This is the default
when the compiler is configured for 68000-based systems.
+It is equivalent to @option{-march=68000}.
Use this option for microcontrollers with a 68000 or EC000 core,
including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356.
+@item -m68010
+@opindex m68010
+Generate output for a 68010. This is the default
+when the compiler is configured for 68010-based systems.
+It is equivalent to @option{-march=68010}.
+
@item -m68020
@itemx -mc68020
@opindex m68020
@opindex mc68020
Generate output for a 68020. This is the default
when the compiler is configured for 68020-based systems.
-
-@item -m68881
-@opindex m68881
-Generate output containing 68881 instructions for floating point.
-This is the default for most 68020 systems unless @option{--nfp} was
-specified when the compiler was configured.
+It is equivalent to @option{-march=68020}.
@item -m68030
@opindex m68030
Generate output for a 68030. This is the default when the compiler is
-configured for 68030-based systems.
+configured for 68030-based systems. It is equivalent to
+@option{-march=68030}.
@item -m68040
@opindex m68040
Generate output for a 68040. This is the default when the compiler is
-configured for 68040-based systems.
+configured for 68040-based systems. It is equivalent to
+@option{-march=68040}.
This option inhibits the use of 68881/68882 instructions that have to be
emulated by software on the 68040. Use this option if your 68040 does not
@item -m68060
@opindex m68060
Generate output for a 68060. This is the default when the compiler is
-configured for 68060-based systems.
+configured for 68060-based systems. It is equivalent to
+@option{-march=68060}.
This option inhibits the use of 68020 and 68881/68882 instructions that
have to be emulated by software on the 68060. Use this option if your 68060
@opindex mcpu32
Generate output for a CPU32. This is the default
when the compiler is configured for CPU32-based systems.
+It is equivalent to @option{-march=cpu32}.
Use this option for microcontrollers with a
CPU32 or CPU32+ core, including the 68330, 68331, 68332, 68333, 68334,
@item -m5200
@opindex m5200
-Generate output for a 520X ``coldfire'' family cpu. This is the default
+Generate output for a 520X ColdFire CPU. This is the default
when the compiler is configured for 520X-based systems.
+It is equivalent to @option{-mcpu=5206}, and is now deprecated
+in favor of that option.
Use this option for microcontroller with a 5200 core, including
-the MCF5202, MCF5203, MCF5204 and MCF5202.
+the MCF5202, MCF5203, MCF5204 and MCF5206.
+
+@item -m5206e
+@opindex m5206e
+Generate output for a 5206e ColdFire CPU. The option is now
+deprecated in favor of the equivalent @option{-mcpu=5206e}.
+
+@item -m528x
+@opindex m528x
+Generate output for a member of the ColdFire 528X family.
+The option is now deprecated in favor of the equivalent
+@option{-mcpu=528x}.
+
+@item -m5307
+@opindex m5307
+Generate output for a ColdFire 5307 CPU. The option is now deprecated
+in favor of the equivalent @option{-mcpu=5307}.
+
+@item -m5407
+@opindex m5407
+Generate output for a ColdFire 5407 CPU. The option is now deprecated
+in favor of the equivalent @option{-mcpu=5407}.
@item -mcfv4e
@opindex mcfv4e
-Generate output for a ColdFire V4e family cpu (e.g.@: 547x/548x).
+Generate output for a ColdFire V4e family CPU (e.g.@: 547x/548x).
This includes use of hardware floating point instructions.
+The option is equivalent to @option{-mcpu=547x}, and is now
+deprecated in favor of that option.
@item -m68020-40
@opindex m68020-40
68020/68881 or a 68030 or a 68040. The generated code does use the
68881 instructions that are emulated on the 68040.
+The option is equivalent to @option{-march=68020} @option{-mtune=68020-40}.
+
@item -m68020-60
@opindex m68020-60
Generate output for a 68060, without using any of the new instructions.
68020/68881 or a 68030 or a 68040. The generated code does use the
68881 instructions that are emulated on the 68060.
+The option is equivalent to @option{-march=68020} @option{-mtune=68020-60}.
+
+@item -mhard-float
+@itemx -m68881
+@opindex mhard-float
+@opindex m68881
+Generate floating-point instructions. This is the default for 68020
+and above, and for ColdFire devices that have an FPU. It defines the
+macro @samp{__HAVE_68881__} on M680x0 targets and @samp{__mcffpu__}
+on ColdFire targets.
+
@item -msoft-float
@opindex msoft-float
-Generate output containing library calls for floating point.
-@strong{Warning:} the requisite libraries are not available for all m68k
-targets. Normally the facilities of the machine's usual C compiler are
-used, but this can't be done directly in cross-compilation. You must
-make your own arrangements to provide suitable library functions for
-cross-compilation. The embedded targets @samp{m68k-*-aout} and
-@samp{m68k-*-coff} do provide software floating point support.
+Do not generate floating-point instructions; use library calls instead.
+This is the default for 68000, 68010, and 68832 targets. It is also
+the default for ColdFire devices that have no FPU.
+
+@item -mdiv
+@itemx -mno-div
+@opindex mdiv
+@opindex mno-div
+Generate (do not generate) ColdFire hardware divide and remainder
+instructions. If @option{-march} is used without @option{-mcpu},
+the default is ``on'' for ColdFire architectures and ``off'' for M680x0
+architectures. Otherwise, the default is taken from the target CPU
+(either the default CPU, or the one specified by @option{-mcpu}). For
+example, the default is ``off'' for @option{-mcpu=5206} and ``on'' for
+@option{-mcpu=5206e}.
+
+gcc defines the macro @samp{__mcfhwdiv__} when this option is enabled.
@item -mshort
@opindex mshort
Additionally, parameters passed on the stack are also aligned to a
16-bit boundary even on targets whose API mandates promotion to 32-bit.
+@item -mno-short
+@opindex -mno-short
+Do not consider type @code{int} to be 16 bits wide. This is the default.
+
@item -mnobitfield
+@itemx -mno-bitfield
@opindex mnobitfield
+@opindex mno-bitfield
Do not use the bit-field instructions. The @option{-m68000}, @option{-mcpu32}
and @option{-m5200} options imply @w{@option{-mnobitfield}}.
The @code{rtd} instruction is supported by the 68010, 68020, 68030,
68040, 68060 and CPU32 processors, but not by the 68000 or 5200.
+@item -mno-rtd
+@opindex mno-rtd
+Do not use the calling conventions selected by @option{-mrtd}.
+This is the default.
+
@item -malign-int
@itemx -mno-align-int
@opindex malign-int
@samp{mips32}, @samp{mips32r2}, and @samp{mips64}.
The processor names are:
@samp{4kc}, @samp{4km}, @samp{4kp},
+@samp{4kec}, @samp{4kem}, @samp{4kep},
@samp{5kc}, @samp{5kf},
@samp{20kc},
-@samp{24k}, @samp{24kc}, @samp{24kf}, @samp{24kx},
+@samp{24kc}, @samp{24kf}, @samp{24kx},
+@samp{24kec}, @samp{24kef}, @samp{24kex},
+@samp{34kc}, @samp{34kf}, @samp{34kx},
@samp{m4k},
@samp{orion},
@samp{r2000}, @samp{r3000}, @samp{r3900}, @samp{r4000}, @samp{r4400},
For information about the O64 ABI, see
@w{@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
+@option{-mabi=32} @option{-mfp64}. This ABI relies on the @samp{mthc1}
+and @samp{mfhc1} instructions and is therefore only supported for
+MIPS32R2 processors.
+
+The register assignments for arguments and return values remain the
+same, but each scalar value is passed in a single 64-bit register
+rather than a pair of 32-bit registers. For example, scalar
+floating-point values are returned in @samp{$f0} only, not a
+@samp{$f0}/@samp{$f1} pair. The set of call-saved registers also
+remains the same, but all 64 bits are saved.
+
@item -mabicalls
@itemx -mno-abicalls
@opindex mabicalls
@itemx -mno-check-zero-division
@opindex mcheck-zero-division
@opindex mno-check-zero-division
-Trap (do not trap) on integer division by zero. The default is
-@option{-mcheck-zero-division}.
+Trap (do not trap) on integer division by zero.
+
+The default is @option{-mcheck-zero-division}.
@item -mdivide-traps
@itemx -mdivide-breaks
@itemx -mno-popcntb
@itemx -mfprnd
@itemx -mno-fprnd
+@itemx -mmfpgpr
+@itemx -mno-mfpgpr
@opindex mpower
@opindex mno-power
@opindex mpower2
@opindex mno-popcntb
@opindex mfprnd
@opindex mno-fprnd
+@opindex mmfpgpr
+@opindex mno-mfpgpr
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
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{-mmfpgpr} option allows GCC to generate the FP move to/from
+general purpose register instructions implemented on the POWER6X
+processor and other processors that support the extended PowerPC V2.05
+architecture.
The @option{-mpowerpc64} option allows GCC to generate the additional
64-bit instructions that are found in the full PowerPC64 architecture
@samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
@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{power5+},
-@samp{common}, @samp{powerpc}, @samp{powerpc64},
+@samp{power4}, @samp{power5}, @samp{power5+}, @samp{power6},
+@samp{power6x}, @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{-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}.
+following options:
+
+@gccoptlist{-maltivec -mfprnd -mhard-float -mmfcrf -mmultiple @gol
+-mnew-mnemonics -mpopcntb -mpower -mpower2 -mpowerpc64 @gol
+-mpowerpc-gpopt -mpowerpc-gfxopt -mstring -mmulhw -mdlmzb -mmfpgpr}
+
+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 because
@option{-mno-isel} instead.
@item -mspe
-@itemx -mno-isel
+@itemx -mno-spe
@opindex mspe
@opindex mno-spe
This switch enables or disables the generation of SPE simd
@itemx -mno-longcall
@opindex mlongcall
@opindex mno-longcall
-Default to making all function calls indirectly, using a register, so
-that functions which reside further than 32 megabytes (33,554,432
-bytes) from the current location can be called. This setting can be
-overridden by the @code{shortcall} function attribute, or by
-@code{#pragma longcall(0)}.
+By default assume that all calls are far away so that a longer more
+expensive calling sequence is required. This is required for calls
+further than 32 megabytes (33,554,432 bytes) from the current location.
+A short call will be generated if the compiler knows
+the call cannot be that far away. This setting can be overridden by
+the @code{shortcall} function attribute, or by @code{#pragma
+longcall(0)}.
Some linkers are capable of detecting out-of-range calls and generating
glue code on the fly. On these systems, long calls are unnecessary and
at an address aligned to the value given by @var{stack-size}.
@end table
+@node Score Options
+@subsection Score Options
+@cindex Score Options
+
+These options are defined for Score implementations:
+
+@table @gcctabopt
+@item -mel
+@opindex -mel
+Compile code for little endian mode.
+
+@item -meb
+@opindex meb
+Compile code for big endian mode. This is the default.
+
+@item -mmac
+@opindex mmac
+Enable the use of multiply-accumulate instructions. Disabled by default.
+
+@item -mscore5u
+@opindex mscore5u
+Specify the SCORE5U of the target architecture.
+
+@item -mscore7
+@opindex mscore7
+Specify the SCORE7 of the target architecture. This is the default.
+@end table
+
@node SH Options
@subsection SH Options
floating point comparison, therefore the default is set to
@option{-ffinite-math-only}.
+@item -minline-ic_invalidate
+@opindex minline-ic_invalidate
+Inline code to invalidate instruction cache entries after setting up
+nested function trampolines.
+This option has no effect if -musermode is in effect and the selected
+code generation option (e.g. -m4) does not allow the use of the icbi
+instruction.
+If the selected code generation option does not allow the use of the icbi
+instruction, and -musermode is not in effect, the inlined code will
+manipulate the instruction cache address array directly with an associative
+write. This not only requires privileged mode, but it will also
+fail if the cache line had been mapped via the TLB and has become unmapped.
+
@item -misize
@opindex misize
Dump instruction size and location in the assembly code.
@item -musermode
@opindex musermode
-Generate a library function call to invalidate instruction cache
-entries, after fixing up a trampoline. This library function call
-doesn't assume it can write to the whole memory address space. This
-is the default when the target is @code{sh-*-linux*}.
+Don't generate privileged mode only code; implies -mno-inline-ic_invalidate
+if the inlined code would not work in user mode.
+This is the default when the target is @code{sh-*-linux*}.
@item -multcost=@var{number}
@opindex multcost=@var{number}
This has the unintentional effect of making it unsafe to schedule ptabs /
ptrel before a branch, or hoist it out of a loop. For example,
__do_global_ctors, a part of libgcc that runs constructors at program
-startup, calls functions in a list which is delimited by -1. With the
--mpt-fixed option, the ptabs will be done before testing against -1.
+startup, calls functions in a list which is delimited by @minus{}1. With the
+-mpt-fixed option, the ptabs will be done before testing against @minus{}1.
That means that all the constructors will be run a bit quicker, but when
the loop comes to the end of the list, the program crashes because ptabs
-loads -1 into a target register. Since this option is unsafe for any
+loads @minus{}1 into a target register. Since this option is unsafe for any
hardware implementing the current architecture specification, the default
is -mno-pt-fixed. Unless the user specifies a specific cost with
@option{-mgettrcost}, -mno-pt-fixed also implies @option{-mgettrcost=100};
This is a synonym for @option{-pthreads}.
@end table
+@node SPU Options
+@subsection SPU Options
+@cindex SPU options
+
+These @samp{-m} options are supported on the SPU:
+
+@table @gcctabopt
+@item -mwarn-reloc
+@itemx -merror-reloc
+@opindex mwarn-reloc
+@opindex merror-reloc
+
+The loader for SPU does not handle dynamic relocations. By default, GCC
+will give an error when it generates code that requires a dynamic
+relocation. @option{-mno-error-reloc} disables the error,
+@option{-mwarn-reloc} will generate a warning instead.
+
+@item -msafe-dma
+@itemx -munsafe-dma
+@opindex msafe-dma
+@opindex munsafe-dma
+
+Instructions which initiate or test completion of DMA must not be
+reordered with respect to loads and stores of the memory which is being
+accessed. Users typically address this problem using the volatile
+keyword, but that can lead to inefficient code in places where the
+memory is known to not change. Rather than mark the memory as volatile
+we treat the DMA instructions as potentially effecting all memory. With
+@option{-munsafe-dma} users must use the volatile keyword to protect
+memory accesses.
+
+@item -mbranch-hints
+@opindex mbranch-hints
+
+By default, GCC will generate a branch hint instruction to avoid
+pipeline stalls for always taken or probably taken branches. A hint
+will not be generated closer than 8 instructions away from its branch.
+There is little reason to disable them, except for debugging purposes,
+or to make an object a little bit smaller.
+
+@item -msmall-mem
+@itemx -mlarge-mem
+@opindex msmall-mem
+@opindex mlarge-mem
+
+By default, GCC generates code assuming that addresses are never larger
+than 18 bits. With @option{-mlarge-mem} code is generated that assumes
+a full 32 bit address.
+
+@item -mstdmain
+@opindex mstdmain
+
+By default, GCC links against startup code that assumes the SPU-style
+main function interface (which has an unconventional parameter list).
+With @option{-mstdmain}, GCC will link your program against startup
+code that assumes a C99-style interface to @code{main}, including a
+local copy of @code{argv} strings.
+
+@item -mfixed-range=@var{register-range}
+@opindex mfixed-range
+Generate code treating the given register range as fixed registers.
+A fixed register is one that the register allocator can not use. This is
+useful when compiling kernel code. A register range is specified as
+two registers separated by a dash. Multiple register ranges can be
+specified separated by a comma.
+
+@end table
+
@node System V Options
@subsection Options for System V
@opindex fbounds-check
For front-ends that support it, generate additional code to check that
indices used to access arrays are within the declared range. This is
-currently only supported by the Java and Fortran 77 front-ends, where
+currently only supported by the Java and Fortran front-ends, where
this option defaults to true and false respectively.
@item -ftrapv
extra information to be omitted and is useful when comparing two assembler
files.
+@item -frecord-gcc-switches
+@opindex frecord-gcc-switches
+This switch causes the command line that was used to invoke the
+compiler to be recorded into the object file that is being created.
+This switch is only implemented on some targets and the exact format
+of the recording is target and binary file format dependent, but it
+usually takes the form of a section containing ASCII text. This
+switch is related to the @option{-fverbose-asm} switch, but that
+switch only records information in the assembler output file as
+comments, so it never reaches the object file.
+
@item -fpic
@opindex fpic
@cindex global offset table
may need to explicitly say @samp{#pragma GCC visibility push(default)}
before including any such headers.
+@samp{extern} declarations are not affected by @samp{-fvisibility}, so
+a lot of code can be recompiled with @samp{-fvisibility=hidden} with
+no modifications. However, this means that calls to @samp{extern}
+functions with no explicit visibility will use the PLT, so it is more
+effective to use @samp{__attribute ((visibility))} and/or
+@samp{#pragma GCC visibility} to tell the compiler which @samp{extern}
+declarations should be treated as hidden.
+
+Note that @samp{-fvisibility} does affect C++ vague linkage
+entities. This means that, for instance, an exception class that will
+be thrown between DSOs must be explicitly marked with default
+visibility so that the @samp{type_info} nodes will be unified between
+the DSOs.
+
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
tries looking in the usual places for the subprogram.
The default value of @env{GCC_EXEC_PREFIX} is
-@file{@var{prefix}/lib/gcc/} where @var{prefix} is the value
+@file{@var{prefix}/lib/gcc/} where @var{prefix} is the prefix to
+the installed compiler. In many cases @var{prefix} is the value
of @code{prefix} when you ran the @file{configure} script.
Other prefixes specified with @option{-B} take precedence over this prefix.
alternate directory name. Thus, with @option{-Bfoo/}, GCC will search
@file{foo/bar} where it would normally search @file{/usr/local/lib/bar}.
These alternate directories are searched first; the standard directories
-come next.
+come next. If a standard directory begins with the configured
+@var{prefix} then the value of @var{prefix} is replaced by
+@env{GCC_EXEC_PREFIX} when looking for header files.
@item COMPILER_PATH
@findex COMPILER_PATH
is to use exactly the same options when generating and using the
precompiled header. The following are known to be safe:
-@gccoptlist{-fmessage-length= -fpreprocessed
--fsched-interblock -fsched-spec -fsched-spec-load -fsched-spec-load-dangerous
--fsched-verbose=<number> -fschedule-insns -fvisibility=
+@gccoptlist{-fmessage-length= -fpreprocessed -fsched-interblock @gol
+-fsched-spec -fsched-spec-load -fsched-spec-load-dangerous @gol
+-fsched-verbose=<number> -fschedule-insns -fvisibility= @gol
-pedantic-errors}
@end itemize
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