@c man begin COPYRIGHT
Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
+2007 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
@c man end
@c man begin BUGS
For instructions on reporting bugs, see
-@w{@uref{http://gcc.gnu.org/bugs.html}}.
+@w{@value{BUGURL}}.
@c man end
@c man begin AUTHOR
See the Info entry for @command{gcc}, or
@cindex order of options
@cindex options, order
You can mix options and other arguments. For the most part, the order
-you use doesn't matter. Order does matter when you use several options
-of the same kind; for example, if you specify @option{-L} more than once,
-the directories are searched in the order specified.
+you use doesn't matter. Order does matter when you use several
+options of the same kind; for example, if you specify @option{-L} more
+than once, the directories are searched in the order specified. Also,
+the placement of the @option{-l} option is significant.
Many options have long names starting with @samp{-f} or with
@samp{-W}---for example,
-frepo -fno-rtti -fstats -ftemplate-depth-@var{n} @gol
-fno-threadsafe-statics -fuse-cxa-atexit -fno-weak -nostdinc++ @gol
-fno-default-inline -fvisibility-inlines-hidden @gol
+-fvisibility-ms-compat @gol
-Wabi -Wctor-dtor-privacy @gol
-Wnon-virtual-dtor -Wreorder @gol
-Weffc++ -Wno-deprecated -Wstrict-null-sentinel @gol
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @gol
--w -Wextra -Wall -Waddress -Waggregate-return -Warray-bounds @gol
+-w -Wextra -Wall -Waddress -Waggregate-return -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
+-Wconversion -Wcoverage-mismatch -Wno-deprecated-declarations @gol
-Wdisabled-optimization -Wno-div-by-zero @gol
-Wempty-body -Wno-endif-labels @gol
-Werror -Werror=* @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
+-Wsign-compare -Wsign-conversion -Wstack-protector @gol
+-Wstrict-aliasing -Wstrict-aliasing=n @gol
-Wstrict-overflow -Wstrict-overflow=@var{n} @gol
-Wswitch -Wswitch-default -Wswitch-enum @gol
--Wsystem-headers -Wtrigraphs -Wundef -Wuninitialized @gol
+-Wsystem-headers -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized @gol
-Wunknown-pragmas -Wno-pragmas -Wunreachable-code @gol
-Wunused -Wunused-function -Wunused-label -Wunused-parameter @gol
-Wunused-value -Wunused-variable @gol
@item Debugging Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
@gccoptlist{-d@var{letters} -dumpspecs -dumpmachine -dumpversion @gol
+-fdbg-cnt-list -fdbg-cnt=@var{counter-value-list} @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
-ftest-coverage -ftime-report -fvar-tracking @gol
-g -g@var{level} -gcoff -gdwarf-2 @gol
-ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ @gol
+-fdebug-prefix-map=@var{old}=@var{new} @gol
-femit-struct-debug-baseonly -femit-struct-debug-reduced @gol
-femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]} @gol
-p -pg -print-file-name=@var{library} -print-libgcc-file-name @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
--finline-limit=@var{n} -fkeep-inline-functions @gol
+-finline-small-functions -finline-limit=@var{n} -fkeep-inline-functions @gol
-fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
--fmodulo-sched -fno-branch-count-reg @gol
+-fmodulo-sched -fmodulo-sched-allow-regmoves -fno-branch-count-reg @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
-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
+-foptimize-sibling-calls -fpredictive-commoning -fprefetch-loop-arrays @gol
-fprofile-generate -fprofile-use @gol
-fregmove -frename-registers @gol
-freorder-blocks -freorder-blocks-and-partition -freorder-functions @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
+-fvariable-expansion-in-unroller -ftree-reassoc @gol
-ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize @gol
-ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts @gol
-fcheck-data-deps @gol
-ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink @gol
-ftree-ch -ftree-sra -ftree-ter -ftree-fre -ftree-vectorize @gol
--ftree-vect-loop-version -ftree-salias -fipa-pta -fweb @gol
+-ftree-vect-loop-version -fvect-cost-model -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}
-mcall-prologues -mno-tablejump -mtiny-stack -mint8}
@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 -mstack-check-l1 -mid-shared-library @gol
--mno-id-shared-library -mshared-library-id=@var{n} @gol
--mleaf-id-shared-library -mno-leaf-id-shared-library @gol
--msep-data -mno-sep-data -mlong-calls -mno-long-calls}
+@gccoptlist{-mcpu=@var{cpu} -msim -momit-leaf-frame-pointer @gol
+-mno-omit-leaf-frame-pointer -mspecld-anomaly -mno-specld-anomaly @gol
+-mcsync-anomaly -mno-csync-anomaly -mlow-64k -mno-low64k @gol
+-mstack-check-l1 -mid-shared-library -mno-id-shared-library @gol
+-mshared-library-id=@var{n} -mleaf-id-shared-library @gol
+-mno-leaf-id-shared-library -msep-data -mno-sep-data -mlong-calls @gol
+-mno-long-calls -mfast-fp -minline-plt}
@emph{CRIS Options}
@gccoptlist{-mcpu=@var{cpu} -march=@var{cpu} -mtune=@var{cpu} @gol
-masm=@var{dialect} -mno-fancy-math-387 @gol
-mno-fp-ret-in-387 -msoft-float @gol
-mno-wide-multiply -mrtd -malign-double @gol
--mpreferred-stack-boundary=@var{num} -mcx16 -msahf @gol
--mmmx -msse -msse2 -msse3 -mssse3 -msse4a -m3dnow -mpopcnt -mabm @gol
+-mpreferred-stack-boundary=@var{num} -mcx16 -msahf -mrecip @gol
+-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 @gol
+-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
--mpc32 -mpc64 -mpc80 mstackrealign @gol
+-mveclibabi=@var{type} -mpc32 -mpc64 -mpc80 -mstackrealign @gol
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
-mcmodel=@var{code-model} @gol
-m32 -m64 -mlarge-data-threshold=@var{num}}
@emph{MIPS Options}
@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
+-mips16 -mno-mips16 -mflip-mips16 @gol
+-mabi=@var{abi} -mabicalls -mno-abicalls @gol
-mshared -mno-shared -mxgot -mno-xgot -mgp32 -mgp64 @gol
-mfp32 -mfp64 -mhard-float -msoft-float @gol
-msingle-float -mdouble-float -mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
+-msmartmips -mno-smartmips @gol
-mpaired-single -mno-paired-single -mdmx -mno-mdmx @gol
-mips3d -mno-mips3d -mmt -mno-mt @gol
-mlong64 -mlong32 -msym32 -mno-sym32 @gol
--G@var{num} -membedded-data -mno-embedded-data @gol
+-G@var{num} -mlocal-sdata -mno-local-sdata @gol
+-mextern-sdata -mno-extern-sdata -mgpopt -mno-gopt @gol
+-membedded-data -mno-embedded-data @gol
-muninit-const-in-rodata -mno-uninit-const-in-rodata @gol
+-mcode-readable=@var{setting} @gol
-msplit-addresses -mno-split-addresses @gol
-mexplicit-relocs -mno-explicit-relocs @gol
-mcheck-zero-division -mno-check-zero-division @gol
-mfix-vr4120 -mno-fix-vr4120 -mfix-vr4130 -mno-fix-vr4130 @gol
-mfix-sb1 -mno-fix-sb1 @gol
-mflush-func=@var{func} -mno-flush-func @gol
--mbranch-likely -mno-branch-likely @gol
+-mbranch-cost=@var{num} -mbranch-likely -mno-branch-likely @gol
-mfp-exceptions -mno-fp-exceptions @gol
-mvr4130-align -mno-vr4130-align}
-misel=yes -misel=no @gol
-mspe -mno-spe @gol
-mspe=yes -mspe=no @gol
+-mpaired @gol
-mvrsave -mno-vrsave @gol
-mmulhw -mno-mulhw @gol
-mdlmzb -mno-dlmzb @gol
-fnon-call-exceptions -funwind-tables @gol
-fasynchronous-unwind-tables @gol
-finhibit-size-directive -finstrument-functions @gol
+-finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{} @gol
+-finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{} @gol
-fno-common -fno-ident @gol
-fpcc-struct-return -fpic -fPIC -fpie -fPIE @gol
-fno-jump-tables @gol
@item @var{file}.hh
@itemx @var{file}.H
+@itemx @var{file}.hp
+@itemx @var{file}.hxx
+@itemx @var{file}.hpp
+@itemx @var{file}.HPP
+@itemx @var{file}.h++
+@itemx @var{file}.tcc
C++ header file to be turned into a precompiled header.
@item @var{file}.f
@item --target-help
@opindex target-help
Print (on the standard output) a description of target-specific command
-line options for each tool.
+line options for each tool. For some targets extra target-specific
+information may also be printed.
@item --help=@var{class}@r{[},@var{qualifier}@r{]}
Print (on the standard output) a description of the command line
@cindex C++ source file suffixes
C++ source files conventionally use one of the suffixes @samp{.C},
@samp{.cc}, @samp{.cpp}, @samp{.CPP}, @samp{.c++}, @samp{.cp}, or
-@samp{.cxx}; C++ header files often use @samp{.hh} or @samp{.H}; and
+@samp{.cxx}; C++ header files often use @samp{.hh}, @samp{.hpp},
+@samp{.H}, or (for shared template code) @samp{.tcc}; and
preprocessed C++ files use the suffix @samp{.ii}. GCC recognizes
files with these names and compiles them as C++ programs even if you
call the compiler the same way as for compiling C programs (usually
as their linkage might otherwise cross a shared library boundary.
@xref{Template Instantiation}.
+@item -fvisibility-ms-compat
+@opindex fvisibility-ms-compat
+This flag attempts to use visibility settings to make GCC's C++
+linkage model compatible with that of Microsoft Visual Studio.
+
+The flag makes these changes to GCC's linkage model:
+
+@enumerate
+@item
+It sets the default visibility to @code{hidden}, like
+@option{-fvisibility=hidden}.
+
+@item
+Types, but not their members, are not hidden by default.
+
+@item
+The One Definition Rule is relaxed for types without explicit
+visibility specifications which are defined in more than one different
+shared object: those declarations are permitted if they would have
+been permitted when this option was not used.
+@end enumerate
+
+In new code it is better to use @option{-fvisibility=hidden} and
+export those classes which are intended to be externally visible.
+Unfortunately it is possible for code to rely, perhaps accidentally,
+on the Visual Studio behavior.
+
+Among the consequences of these changes are that static data members
+of the same type with the same name but defined in different shared
+objects will be different, so changing one will not change the other;
+and that pointers to function members defined in different shared
+objects may not compare equal. When this flag is given, it is a
+violation of the ODR to define types with the same name differently.
+
@item -fno-weak
@opindex fno-weak
Do not use weak symbol support, even if it is provided by the linker.
@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 also
-enabled if -Weffc++ is specified.
+Warn when a class has virtual functions and accessible non-virtual
+destructor, in which case it would be possible but unsafe to delete
+an instance of a derived class through a pointer to the base class.
+This warning is also enabled if -Weffc++ is specified.
@item -Wreorder @r{(C++ only)}
@opindex Wreorder
@item -Wreturn-type
@opindex Wreturn-type
-Warn whenever a function is defined with a return-type that defaults to
-@code{int}. Also warn about any @code{return} statement with no
-return-value in a function whose return-type is not @code{void}.
+@opindex Wno-return-type
+Warn whenever a function is defined with a return-type that defaults
+to @code{int}. Also warn about any @code{return} statement with no
+return-value in a function whose return-type is not @code{void}
+(falling off the end of the function body is considered returning
+without a value), and about a @code{return} statement with a
+expression in a function whose return-type is @code{void}.
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,
compiler is using for optimization. The warning does not catch all
cases, but does attempt to catch the more common pitfalls. It is
included in @option{-Wall}.
+It is equivalent to -Wstrict-aliasing=3
-@item -Wstrict-aliasing=2
-@opindex Wstrict-aliasing=2
+@item -Wstrict-aliasing=n
+@opindex Wstrict-aliasing=n
This option is only active when @option{-fstrict-aliasing} is active.
It warns about code which might break the strict aliasing rules that the
-compiler is using for optimization. This warning catches more cases than
-@option{-Wstrict-aliasing}, but it will also give a warning for some ambiguous
-cases that are safe.
+compiler is using for optimization.
+Higher levels correspond to higher accuracy (fewer false positives).
+Higher levels also correspond to more effort, similar to the way -O works.
+@option{-Wstrict-aliasing} is equivalent to @option{-Wstrict-aliasing=n},
+with n=3.
+
+Level 1: Most aggressive, quick, least accurate.
+Possibly useful when higher levels
+do not warn but -fstrict-aliasing still breaks the code, as it has very few
+false negatives. However, it has many false positives.
+Warns for all pointer conversions between possibly incompatible types,
+even if never dereferenced. Runs in the frontend only.
+
+Level 2: Aggressive, quick, not too precise.
+May still have many false positives (not as many as level 1 though),
+and few false negatives (but possibly more than level 1).
+Unlike level 1, it only warns when an address is taken. Warns about
+incomplete types. Runs in the frontend only.
+
+Level 3 (default for @option{-Wstrict-aliasing}):
+Should have very few false positives and few false
+negatives. Slightly slower than levels 1 or 2 when optimization is enabled.
+Takes care of the common punn+dereference pattern in the frontend:
+@code{*(int*)&some_float}.
+If optimization is enabled, it also runs in the backend, where it deals
+with multiple statement cases using flow-sensitive points-to information.
+Only warns when the converted pointer is dereferenced.
+Does not warn about incomplete types.
@item -Wstrict-overflow
@item -Wstrict-overflow=@var{n}
@itemize @bullet
@item
-A function can return either with or without a value. (Falling
-off the end of the function body is considered returning without
-a value.) For example, this function would evoke such a
-warning:
-
-@smallexample
-@group
-foo (a)
-@{
- if (a > 0)
- return a;
-@}
-@end group
-@end smallexample
-
-@item
-An unsigned value is compared against zero with @samp{<} or @samp{>=}.
+Warn if a comparison is always true or always false due to the limited
+range of the data type, but do not warn for constant expressions. For
+example, warn if an unsigned variable is compared against zero with
+@samp{<} or @samp{>=}. This warning can be independently controlled
+by @option{-Wtype-limits}.
@item @r{(C only)}
Storage-class specifiers like @code{static} are not the first things
@samp{do while} statement. This warning can be independently
controlled by @option{-Wempty-body}.
+@item @r{(C++ only)}
+An empty body occurs in a @samp{while} or @samp{for} statement with no
+whitespacing before the semicolon. This warning can be independently
+controlled by @option{-Wempty-body}.
+
@item
A pointer is compared against integer zero with @samp{<}, @samp{<=},
@samp{>}, or @samp{>=}.
to functions. In C++, warn also when an arithmetic operation involves
@code{NULL}. This warning is also enabled by @option{-pedantic}.
+@item -Wtype-limits
+@opindex Wtype-limits
+@opindex Wno-type-limits
+Warn if a comparison is always true or always false due to the limited
+range of the data type, but do not warn for constant expressions. For
+example, warn if an unsigned variable is compared against zero with
+@samp{<} or @samp{>=}. This warning is also enabled by
+@option{-Wextra}.
+
@item -Wbad-function-cast @r{(C only)}
@opindex Wbad-function-cast
Warn whenever a function call is cast to a non-matching type.
@item -Wconversion
@opindex Wconversion
+@opindex Wno-conversion
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)}.
+changed by the conversion like in @code{abs (2.0)}. Warnings about
+conversions between signed and unsigned integers can be disabled by
+using @option{-Wno-sign-conversion}.
For C++, also warn for conversions between @code{NULL} and non-pointer
types; confusing overload resolution for user-defined conversions; and
conversions that will never use a type conversion operator:
conversions to @code{void}, the same type, a base class or a reference
-to them.
+to them. Warnings about conversions between signed and unsigned
+integers are disabled by default in C++ unless
+@option{-Wsign-conversion} is explicitly enabled.
@item -Wempty-body
@opindex Wempty-body
-An empty body occurs in an @samp{if}, @samp{else} or @samp{do while}
-statement. This warning is also enabled by @option{-Wextra}.
+Warn if an empty body occurs in an @samp{if}, @samp{else} or @samp{do
+while} statement. Additionally, in C++, warn when an empty body occurs
+in a @samp{while} or @samp{for} statement with no whitespacing before
+the semicolon. This warning is also enabled by @option{-Wextra}.
@item -Wsign-compare
@opindex Wsign-compare
This warning is also enabled by @option{-Wextra}; to get the other warnings
of @option{-Wextra} without this warning, use @samp{-Wextra -Wno-sign-compare}.
+@item -Wsign-conversion
+@opindex Wsign-conversion
+@opindex Wno-sign-conversion
+Warn for implicit conversions that may change the sign of an integer
+value, like assigning a signed integer expression to an unsigned
+integer variable. An explicit cast silences the warning. In C, this
+option is enabled also by @option{-Wconversion}.
+
@item -Waddress
@opindex Waddress
@opindex Wno-address
This option works only with DWARF 2.
+@item -fdebug-prefix-map=@var{old}=@var{new}
+@opindex fdebug-prefix-map
+When compiling files in directory @file{@var{old}}, record debugging
+information describing them as in @file{@var{new}} instead.
+
@cindex @command{prof}
@item -p
@opindex p
generate test coverage data. Coverage data will match the source files
more closely, if you do not optimize.
+@item -fdbg-cnt-list
+@opindex fdbg-cnt-list
+Print the name and the counter upperbound for all debug counters.
+
+@item -fdbg-cnt=@var{counter-value-list}
+@opindex fdbg-cnt
+Set the internal debug counter upperbound. @var{counter-value-list}
+is a comma-separated list of @var{name}:@var{value} pairs
+which sets the upperbound of each debug counter @var{name} to @var{value}.
+All debug counters have the initial upperbound of @var{UINT_MAX},
+thus dbg_cnt() returns true always unless the upperbound is set by this option.
+e.g. With -fdbg-cnt=dce:10,tail_call:0
+dbg_cnt(dce) will return true only for first 10 invocations
+and dbg_cnt(tail_call) will return false always.
+
@item -d@var{letters}
@item -fdump-rtl-@var{pass}
@opindex d
compiler. The file names for most of the dumps are made by appending a
pass number and a word to the @var{dumpname}. @var{dumpname} is generated
from the name of the output file, if explicitly specified and it is not
-an executable, otherwise it is the basename of the source file.
+an executable, otherwise it is the basename of the source file. These
+switches may have different effects when @option{-E} is used for
+preprocessing.
Most debug dumps can be enabled either passing a letter to the @option{-d}
option, or with a long @option{-fdump-rtl} switch; here are the possible
@opindex dM
@opindex fdump-rtl-mach
Dump after performing the machine dependent reorganization pass, to
-@file{@var{file}.155r.mach}.
+@file{@var{file}.155r.mach} if that pass exists.
@item -dn
@itemx -fdump-rtl-rnreg
@item -fdump-unnumbered
@opindex fdump-unnumbered
When doing debugging dumps (see @option{-d} option above), suppress instruction
-numbers, line number note and address output. This makes it more feasible to
+numbers 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}.
-ftree-fre @gol
-ftree-ch @gol
-funit-at-a-time @gol
+-finline-small-functions @gol
-fmerge-constants}
@option{-O} also turns on @option{-fomit-frame-pointer} on machines
@opindex O3
Optimize yet more. @option{-O3} turns on all optimizations specified by
@option{-O2} and also turns on the @option{-finline-functions},
-@option{-funswitch-loops} and @option{-fgcse-after-reload} options.
+@option{-funswitch-loops}, @option{-fpredictive-commoning} and
+@option{-fgcse-after-reload} options.
@item -O0
@opindex O0
is used to keep the compiler from expanding any functions inline.
Note that if you are not optimizing, no functions can be expanded inline.
+@item -finline-small-functions
+@opindex finline-small-functions
+Integrate functions into their callers when their body is smaller than expected
+function call code (so overall size of program gets smaller). The compiler
+heuristically decides which functions are simple enough to be worth integrating
+in this way.
+
+Enabled at level @option{-O2}.
+
@item -finline-functions
@opindex finline-functions
Integrate all simple functions into their callers. The compiler
pass. This pass looks at innermost loops and reorders their
instructions by overlapping different iterations.
+@item -fmodulo-sched-allow-regmoves
+@opindex fmodulo-sched-allow-regmoves
+Perform more aggressive SMS based modulo scheduling with register moves
+allowed. By setting this flag certain anti-dependences edges will be
+deleted which will trigger the generation of reg-moves based on the
+life-range analysis. This option is effective only with
+@option{-fmodulo-sched} enabled.
+
@item -fno-branch-count-reg
@opindex fno-branch-count-reg
Do not use ``decrement and branch'' instructions on a count register,
@item -freschedule-modulo-scheduled-loops
@opindex fscheduling-in-modulo-scheduled-loops
-The modulo scheduling comes before the traditional scheduling, if a loop was modulo scheduled
-we may want to prevent the later scheduling passes from changing its schedule, we use this
-option to control that.
+The modulo scheduling comes before the traditional scheduling, if a loop
+was modulo scheduled we may want to prevent the later scheduling passes
+from changing its schedule, we use this option to control that.
@item -fcaller-saves
@opindex fcaller-saves
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -ftree-reassoc
+Perform Reassociation on trees This flag is enabled by default
+at @option{-O} and higher.
+
@item -ftree-pre
Perform Partial Redundancy Elimination (PRE) on trees. This flag is
enabled by default at @option{-O2} and @option{-O3}.
performs jump threading (to reduce jumps to jumps). This flag is
enabled by default at @option{-O} and higher.
+@item -ftree-dse
+@opindex ftree-dse
+Perform dead store elimination (DSE) on trees. A dead store is a store into
+a memory location which will later be overwritten by another store without
+any intervening loads. In this case the earlier store can be deleted. 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
effectiveness of code motion optimizations. It also saves one jump. This flag
to control which version is executed. This option is enabled by default
except at level @option{-Os} where it is disabled.
+@item -fvect-cost-model
+Enable cost model for vectorization.
+
@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
With this option, the compiler will create multiple copies of some
local variables when unrolling a loop which can result in superior code.
+@item -fpredictive-commoning
+@opindex fpredictive-commoning
+Perform predictive commoning optimization, i.e., reusing computations
+(especially memory loads and stores) performed in previous
+iterations of loops.
+
+This option is enabled at level @option{-O3}.
+
@item -fprefetch-loop-arrays
@opindex fprefetch-loop-arrays
If supported by the target machine, generate instructions to prefetch
@item -funsafe-math-optimizations
@opindex funsafe-math-optimizations
+
Allow optimizations for floating-point arithmetic that (a) assume
that arguments and results are valid and (b) may violate IEEE or
ANSI standards. When used at link-time, it may include libraries
an exact implementation of IEEE or ISO rules/specifications for
math functions. It may, however, yield faster code for programs
that do not require the guarantees of these specifications.
+Enables @option{-freciprocal-math} and @option{-fassociative-math}.
The default is @option{-fno-unsafe-math-optimizations}.
+@item -fassociative-math
+@opindex -fassociative-math
+
+Allow re-association of operands in series of floating-point operations.
+This violates the ISO C and C++ language standard by possibly changing
+computation result. NOTE: re-ordering may change the sign of zero as
+well as ignore NaNs and inhibit or create underflow or overflow (and
+thus cannot be used on a code which relies on rounding behavior like
+@code{(x + 2**52) - 2**52)}. May also reorder floating-point comparisons
+and thus may not be used when ordered comparisons are required.
+This flag doesn't make much sense without @option{-fno-signed-zeros}
+or @option{-fno-trapping-math} or with @option{-frounding-math}.
+
+The default is @option{-fno-associative-math}.
+
+@item -freciprocal-math
+@opindex -freciprocal-math
+
+Allow the reciprocal of a value to be used instead of dividing by
+the value if this enables optimizations. For example @code{x / y}
+can be replaced with @code{x * (1/y)} which is useful if @code{(1/y)}
+is subject to common subexpression elimination. Note that this loses
+precision and increases the number of flops operating on the value.
+
+The default is @option{-fno-reciprocal-math}.
+
@item -ffinite-math-only
@opindex ffinite-math-only
Allow optimizations for floating-point arithmetic that assume
When set to 1, use expensive methods to eliminate all redundant
constraints. The default value is 0.
-@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 vect-max-version-for-alignment-checks
+The maximum number of runtime checks that can be performed when
+doing loop versioning for alignment in the vectorizer. See option
+ftree-vect-loop-version for more information.
+
+@item vect-max-version-for-alias-checks
+The maximum number of runtime checks that can be performed when
+doing loop versioning for alias in the vectorizer. See option
+ftree-vect-loop-version for more information.
@item max-iterations-to-track
The size of cache line in L1 cache, in bytes.
@item l1-cache-size
-The number of cache lines in L1 cache.
+The size of L1 cache, in kilobytes.
-@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).
+@item l2-cache-size
+The size of L2 cache, in kilobytes.
+
+@item use-canonical-types
+Whether the compiler should use the ``canonical'' type system. By
+default, this should always be 1, which uses a more efficient internal
+mechanism for comparing types in C++ and Objective-C++. However, if
+bugs in the canonical type system are causing compilation failures,
+set this value to 0 to disable canonical types.
@end table
@end table
%@{fgnu-runtime:%:replace-outfile(-lobjc -lobjc-gnu)@}
@end smallexample
+@item @code{print-asm-header}
+The @code{print-asm-header} function takes no arguments and simply
+prints a banner like:
+
+@smallexample
+Assembler options
+=================
+
+Use "-Wa,OPTION" to pass "OPTION" to the assembler.
+@end smallexample
+
+It is used to separate compiler options from assembler options
+in the @option{--target-help} output.
@end table
@item %@{@code{S}@}
@cindex Blackfin Options
@table @gcctabopt
+@item -mcpu=@var{cpu}
+@opindex mcpu=
+Specifies the name of the target Blackfin processor. Currently, @var{cpu}
+can be one of @samp{bf531}, @samp{bf532}, @samp{bf533},
+@samp{bf534}, @samp{bf536}, @samp{bf537}, @samp{bf561}.
+Without this option, @samp{bf532} is used as the processor by default.
+The corresponding predefined processor macros for @var{cpu} is to
+be defined. For the @samp{bfin-elf} toolchain, this causes the hardware
+BSP provided by libgloss to be linked in if @samp{-msim} is not given.
+Support for @samp{bf561} is incomplete; only the processor macro is defined.
+
+@item -msim
+@opindex msim
+Specifies that the program will be run on the simulator. This causes
+the simulator BSP provided by libgloss to be linked in. This option
+has effect only for @samp{bfin-elf} toolchain.
+
@item -momit-leaf-frame-pointer
@opindex momit-leaf-frame-pointer
Don't keep the frame pointer in a register for leaf functions. This
@option{-mno-long-calls} will restore the default behavior. Note these
switches have no effect on how the compiler generates code to handle
function calls via function pointers.
+
+@item -mfast-fp
+@opindex mfast-fp
+Link with the fast floating-point library. This library relaxes some of
+the IEEE floating-point standard's rules for checking inputs against
+Not-a-Number (NAN), in the interest of performance.
+
+@item -minline-plt
+@opindex minline-plt
+Enable inlining of PLT entries in function calls to functions that are
+not known to bind locally. It has no effect without @option{-mfdpic}.
@end table
@node CRIS Options
is @var{version}. Typical values of @var{version} include @code{10.1},
@code{10.2}, and @code{10.3.9}.
-The default for this option is to make choices that seem to be most
-useful.
+If the compiler was built to use the system's headers by default,
+then the default for this option is the system version on which the
+compiler is running, otherwise the default is to make choices which
+are compatible with as many systems and code bases as possible.
@item -mkernel
@opindex mkernel
@item -mvms-return-codes
@opindex mvms-return-codes
Return VMS condition codes from main. The default is to return POSIX
-style condition (e.g.@ error) codes.
+style condition (e.g.@: error) codes.
@end table
@node FRV Options
@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 k8-sse3, opteron-sse3, athlon64-sse3
+Improved versions of k8, opteron and athlon64 with SSE3 instruction set support.
@item amdfam10, barcelona
-AMD Family 10 core based CPUs with x86-64 instruction set support. (This
+AMD Family 10h 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
@opindex mcpu
A deprecated synonym for @option{-mtune}.
-@item -m386
-@itemx -m486
-@itemx -mpentium
-@itemx -mpentiumpro
-@opindex m386
-@opindex m486
-@opindex mpentium
-@opindex mpentiumpro
-These options are synonyms for @option{-mtune=i386}, @option{-mtune=i486},
-@option{-mtune=pentium}, and @option{-mtune=pentiumpro} respectively.
-These synonyms are deprecated.
-
@item -mfpmath=@var{unit}
@opindex march
Generate floating point arithmetics for selected unit @var{unit}. The choices
@opindex mpc80
Set 80387 floating-point precision to 32, 64 or 80 bits. When @option{-mpc32}
-is specified, the significand of floating-point operations is rounded to 24
-bits (single precision), @option{-mpc64} rounds the significand of
-floating-point operations to 53 bits (double precision) and @option{-mpc80}
-rounds the significand of floating-point operations to 64 bits (extended
-double precision). Note that a change of default precision control may
-affect the results returned by some of the mathematical functions.
+is specified, the significands of results of floating-point operations are
+rounded to 24 bits (single precision); @option{-mpc64} rounds the the
+significands of results of floating-point operations to 53 bits (double
+precision) and @option{-mpc80} rounds the significands of results of
+floating-point operations to 64 bits (extended double precision), which is
+the default. When this option is used, floating-point operations in higher
+precisions are not available to the programmer without setting the FPU
+control word explicitly.
+
+Setting the rounding of floating-point operations to less than the default
+80 bits can speed some programs by 2% or more. Note that some mathematical
+libraries assume that extended precision (80 bit) floating-point operations
+are enabled by default; routines in such libraries could suffer significant
+loss of accuracy, typically through so-called "catastrophic cancellation",
+when this option is used to set the precision to less than extended precision.
@item -mstackrealign
@opindex mstackrealign
@itemx -mno-sse3
@item -mssse3
@itemx -mno-ssse3
+@item -msse4.1
+@itemx -mno-sse4.1
+@item -msse4.2
+@itemx -mno-sse4.2
+@item -msse4
+@itemx -mno-sse4
@item -msse4a
@item -mno-sse4a
@item -m3dnow
@opindex m3dnow
@opindex mno-3dnow
These switches enable or disable the use of instructions in the MMX,
-SSE, SSE2, SSE3, SSSE3, SSE4A, ABM or 3DNow! extended instruction sets.
+SSE, SSE2, SSE3, SSSE3, SSE4.1, 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.
In 64-bit mode, SAHF instruction is used to optimize @code{fmod}, @code{drem}
or @code{remainder} built-in functions: see @ref{Other Builtins} for details.
+@item -mrecip
+@opindex mrecip
+This option will enable GCC to use RCPSS and RSQRTSS instructions (and their
+vectorized variants RCPPS and RSQRTPS) instead of DIVSS and SQRTSS (and their
+vectorized variants). These instructions will be generated only when
+@option{-funsafe-math-optimizations} is enabled.
+
+@item -mveclibabi=@var{type}
+@opindex mveclibabi
+Specifies the ABI type to use for vectorizing intrinsics using an
+external library. Supported types are @code{acml} for the AMD
+math core library style of interfacing. GCC will currently emit
+calls to @code{__vrd2_sin}, @code{__vrd2_cos}, @code{__vrd2_exp},
+@code{__vrd2_log}, @code{__vrd2_log2}, @code{__vrd2_log10},
+@code{__vrs4_sinf}, @code{__vrs4_cosf}, @code{__vrs4_expf},
+@code{__vrs4_logf}, @code{__vrs4_log2f}, @code{__vrs4_log10f}
+and @code{__vrs4_powf} when using this type and @option{-ftree-vectorize}
+is enabled. A ACML ABI compatible library will have to be specified
+at link time.
+
@item -mpush-args
@itemx -mno-push-args
@opindex mpush-args
@samp{mips1}, @samp{mips2}, @samp{mips3}, @samp{mips4},
@samp{mips32}, @samp{mips32r2}, and @samp{mips64}.
The processor names are:
-@samp{4kc}, @samp{4km}, @samp{4kp},
-@samp{4kec}, @samp{4kem}, @samp{4kep},
+@samp{4kc}, @samp{4km}, @samp{4kp}, @samp{4ksc},
+@samp{4kec}, @samp{4kem}, @samp{4kep}, @samp{4ksd},
@samp{5kc}, @samp{5kf},
@samp{20kc},
-@samp{24kc}, @samp{24kf}, @samp{24kx},
-@samp{24kec}, @samp{24kef}, @samp{24kex},
-@samp{34kc}, @samp{34kf}, @samp{34kx},
-@samp{74kc}, @samp{74kf}, @samp{74kx},
+@samp{24kc}, @samp{24kf2_1}, @samp{24kf1_1},
+@samp{24kec}, @samp{24kef2_1}, @samp{24kef1_1},
+@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1},
+@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
@samp{m4k},
@samp{orion},
@samp{r2000}, @samp{r3000}, @samp{r3900}, @samp{r4000}, @samp{r4400},
(for example, @samp{-march=r2k}). Prefixes are optional, and
@samp{vr} may be written @samp{r}.
+Names of the form @samp{@var{n}f2_1} refer to processors with
+FPUs clocked at half the rate of the core, names of the form
+@samp{@var{n}f1_1} refer to processors with FPUs clocked at the same
+rate as the core, and names of the form @samp{@var{n}f3_2} refer to
+processors with FPUs clocked a ratio of 3:2 with respect to the core.
+For compatibility reasons, @samp{@var{n}f} is accepted as a synonym
+for @samp{@var{n}f2_1} while @samp{@var{n}x} and @samp{@var{b}fx} are
+accepted as synonyms for @samp{@var{n}f1_1}.
+
GCC defines two macros based on the value of this option. The first
is @samp{_MIPS_ARCH}, which gives the name of target architecture, as
a string. The second has the form @samp{_MIPS_ARCH_@var{foo}},
Generate (do not generate) MIPS16 code. If GCC is targetting a
MIPS32 or MIPS64 architecture, it will make use of the MIPS16e ASE@.
+MIPS16 code generation can also be controlled on a per-function basis
+by means of @code{mips16} and @code{nomips16} attributes.
+@xref{Function Attributes}, for more information.
+
+@item -mflip-mips16
+@opindex mflip-mips16
+Generate MIPS16 code on alternating functions. This option is provided
+for regression testing of mixed MIPS16/non-MIPS16 code generation, and is
+not intended for ordinary use in compiling user code.
+
@item -mabi=32
@itemx -mabi=o64
@itemx -mabi=n32
@itemx -mno-dsp
@opindex mdsp
@opindex mno-dsp
-Use (do not use) the MIPS DSP ASE. @xref{MIPS DSP Built-in Functions}.
+Use (do not use) revision 1 of the MIPS DSP ASE.
+@xref{MIPS DSP Built-in Functions}. This option defines the
+preprocessor macro @samp{__mips_dsp}. It also defines
+@samp{__mips_dsp_rev} to 1.
@item -mdspr2
@itemx -mno-dspr2
@opindex mdspr2
@opindex mno-dspr2
-Use (do not use) the MIPS DSP ASE REV 2. @xref{MIPS DSP Built-in Functions}.
-The option @option{-mdspr2} implies @option{-mdsp}.
+Use (do not use) revision 2 of the MIPS DSP ASE.
+@xref{MIPS DSP Built-in Functions}. This option defines the
+preprocessor macros @samp{__mips_dsp} and @samp{__mips_dspr2}.
+It also defines @samp{__mips_dsp_rev} to 2.
+
+@item -msmartmips
+@itemx -mno-smartmips
+@opindex msmartmips
+@opindex mno-smartmips
+Use (do not use) the MIPS SmartMIPS ASE.
@item -mpaired-single
@itemx -mno-paired-single
@item -G @var{num}
@opindex G
-@cindex smaller data references (MIPS)
-@cindex gp-relative references (MIPS)
-Put global and static items less than or equal to @var{num} bytes into
-the small data or bss section instead of the normal data or bss section.
-This allows the data to be accessed using a single instruction.
+Put definitions of externally-visible data in a small data section
+if that data is no bigger than @var{num} bytes. GCC can then access
+the data more efficiently; see @option{-mgpopt} for details.
+
+The default @option{-G} option depends on the configuration.
+
+@item -mlocal-sdata
+@itemx -mno-local-sdata
+@opindex mlocal-sdata
+@opindex mno-local-sdata
+Extend (do not extend) the @option{-G} behavior to local data too,
+such as to static variables in C. @option{-mlocal-sdata} is the
+default for all configurations.
+
+If the linker complains that an application is using too much small data,
+you might want to try rebuilding the less performance-critical parts with
+@option{-mno-local-sdata}. You might also want to build large
+libraries with @option{-mno-local-sdata}, so that the libraries leave
+more room for the main program.
+
+@item -mextern-sdata
+@itemx -mno-extern-sdata
+@opindex mextern-sdata
+@opindex mno-extern-sdata
+Assume (do not assume) that externally-defined data will be in
+a small data section if that data is within the @option{-G} limit.
+@option{-mextern-sdata} is the default for all configurations.
+
+If you compile a module @var{Mod} with @option{-mextern-sdata} @option{-G
+@var{num}} @option{-mgpopt}, and @var{Mod} references a variable @var{Var}
+that is no bigger than @var{num} bytes, you must make sure that @var{Var}
+is placed in a small data section. If @var{Var} is defined by another
+module, you must either compile that module with a high-enough
+@option{-G} setting or attach a @code{section} attribute to @var{Var}'s
+definition. If @var{Var} is common, you must link the application
+with a high-enough @option{-G} setting.
+
+The easiest way of satisfying these restrictions is to compile
+and link every module with the same @option{-G} option. However,
+you may wish to build a library that supports several different
+small data limits. You can do this by compiling the library with
+the highest supported @option{-G} setting and additionally using
+@option{-mno-extern-sdata} to stop the library from making assumptions
+about externally-defined data.
+
+@item -mgpopt
+@itemx -mno-gpopt
+@opindex mgpopt
+@opindex mno-gpopt
+Use (do not use) GP-relative accesses for symbols that are known to be
+in a small data section; see @option{-G}, @option{-mlocal-sdata} and
+@option{-mextern-sdata}. @option{-mgpopt} is the default for all
+configurations.
-All modules should be compiled with the same @option{-G @var{num}}
-value.
+@option{-mno-gpopt} is useful for cases where the @code{$gp} register
+might not hold the value of @code{_gp}. For example, if the code is
+part of a library that might be used in a boot monitor, programs that
+call boot monitor routines will pass an unknown value in @code{$gp}.
+(In such situations, the boot monitor itself would usually be compiled
+with @option{-G0}.)
+
+@option{-mno-gpopt} implies @option{-mno-local-sdata} and
+@option{-mno-extern-sdata}.
@item -membedded-data
@itemx -mno-embedded-data
Put uninitialized @code{const} variables in the read-only data section.
This option is only meaningful in conjunction with @option{-membedded-data}.
+@item -mcode-readable=@var{setting}
+@opindex mcode-readable
+Specify whether GCC may generate code that reads from executable sections.
+There are three possible settings:
+
+@table @gcctabopt
+@item -mcode-readable=yes
+Instructions may freely access executable sections. This is the
+default setting.
+
+@item -mcode-readable=pcrel
+MIPS16 PC-relative load instructions can access executable sections,
+but other instructions must not do so. This option is useful on 4KSc
+and 4KSd processors when the code TLBs have the Read Inhibit bit set.
+It is also useful on processors that can be configured to have a dual
+instruction/data SRAM interface and that, like the M4K, automatically
+redirect PC-relative loads to the instruction RAM.
+
+@item -mcode-readable=no
+Instructions must not access executable sections. This option can be
+useful on targets that are configured to have a dual instruction/data
+SRAM interface but that (unlike the M4K) do not automatically redirect
+PC-relative loads to the instruction RAM.
+@end table
+
@item -msplit-addresses
@itemx -mno-split-addresses
@opindex msplit-addresses
depends on the target GCC was configured for, but commonly is either
@samp{_flush_func} or @samp{__cpu_flush}.
+@item mbranch-cost=@var{num}
+@opindex mbranch-cost
+Set the cost of branches to roughly @var{num} ``simple'' instructions.
+This cost is only a heuristic and is not guaranteed to produce
+consistent results across releases. A zero cost redundantly selects
+the default, which is based on the @option{-mtune} setting.
+
@item -mbranch-likely
@itemx -mno-branch-likely
@opindex mbranch-likely
This switch enables or disables the generation of SPE simd
instructions.
+@item -mpaired
+@itemx -mno-paired
+@opindex mpaired
+@opindex mno-paired
+This switch enables or disables the generation of PAIRED simd
+instructions.
+
@item -mspe=@var{yes/no}
This option has been deprecated. Use @option{-mspe} and
@option{-mno-spe} instead.
cannot safely be called (perhaps signal handlers, if the profiling
routines generate output or allocate memory).
+@item -finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{}
+@opindex finstrument-functions-exclude-file-list
+
+Set the list of functions that are excluded from instrumentation (see
+the description of @code{-finstrument-functions}). If the file that
+contains a function definition matches with one of @var{file}, then
+that function is not instrumented. The match is done on substrings:
+if the @var{file} parameter is a substring of the file name, it is
+considered to be a match.
+
+For example,
+@code{-finstrument-functions-exclude-file-list=/bits/stl,include/sys}
+will exclude any inline function defined in files whose pathnames
+contain @code{/bits/stl} or @code{include/sys}.
+
+If, for some reason, you want to include letter @code{','} in one of
+@var{sym}, write @code{'\,'}. For example,
+@code{-finstrument-functions-exclude-file-list='\,\,tmp'}
+(note the single quote surrounding the option).
+
+@item -finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{}
+@opindex finstrument-functions-exclude-function-list
+
+This is similar to @code{-finstrument-functions-exclude-file-list},
+but this option sets the list of function names to be excluded from
+instrumentation. The function name to be matched is its user-visible
+name, such as @code{vector<int> blah(const vector<int> &)}, not the
+internal mangled name (e.g., @code{_Z4blahRSt6vectorIiSaIiEE}). The
+match is done on substrings: if the @var{sym} parameter is a substring
+of the function name, it is considered to be a match.
+
@item -fstack-check
@opindex fstack-check
Generate code to verify that you do not go beyond the boundary of the