@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,
+@samp{-W}---for example,
@option{-fmove-loop-invariants}, @option{-Wformat} and so on. Most of
these have both positive and negative forms; the negative form of
@option{-ffoo} would be @option{-fno-foo}. This manual documents
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
@gccoptlist{-c -S -E -o @var{file} -combine -pipe -pass-exit-codes @gol
--x @var{language} -v -### --help@r{[}=@var{class}@r{]} --target-help @gol
+-x @var{language} -v -### --help@r{[}=@var{class}@r{]} --target-help @gol
--version @@@var{file}}
@item C Language Options
-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
-print-multi-directory -print-multi-lib @gol
-print-prog-name=@var{program} -print-search-dirs -Q @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
+-fcheck-data-deps -ftree-parallelize-loops @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
+@gccoptlist{-mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]} @gol
+-msim -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}
+-msep-data -mno-sep-data -mlong-calls -mno-long-calls @gol
+-mfast-fp -minline-plt}
@emph{CRIS Options}
@gccoptlist{-mcpu=@var{cpu} -march=@var{cpu} -mtune=@var{cpu} @gol
@gccoptlist{-mtune=@var{cpu-type} -march=@var{cpu-type} @gol
-mfpmath=@var{unit} @gol
-masm=@var{dialect} -mno-fancy-math-387 @gol
--mno-fp-ret-in-387 -msoft-float -msvr3-shlib @gol
+-mno-fp-ret-in-387 -msoft-float @gol
-mno-wide-multiply -mrtd -malign-double @gol
--mpreferred-stack-boundary=@var{num} @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 -msse5 @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
--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}}
+-m32 -m64 -mlarge-data-threshold=@var{num} @gol
+-mfused-madd -mno-fused-madd}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
@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
--mshared -mno-shared -mxgot -mno-xgot -mgp32 -mgp64 @gol
--mfp32 -mfp64 -mhard-float -msoft-float @gol
--msingle-float -mdouble-float -mdsp -mdspr2 -mpaired-single -mips3d @gol
+-mips16 -mno-mips16 -mflip-mips16 @gol
+-minterlink-mips16 -mno-interlink-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 -mllsc -mno-llsc @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
--msplit-addresses -mno-split-addresses @gol
--mexplicit-relocs -mno-explicit-relocs @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
-mdivide-traps -mdivide-breaks @gol
-mmemcpy -mno-memcpy -mlong-calls -mno-long-calls @gol
-mmad -mno-mad -mfused-madd -mno-fused-madd -nocpp @gol
-mfix-r4000 -mno-fix-r4000 -mfix-r4400 -mno-fix-r4400 @gol
--mfix-vr4120 -mno-fix-vr4120 -mfix-vr4130 @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
-mwarn-framesize -mwarn-dynamicstack -mstack-size -mstack-guard}
@emph{Score Options}
-@gccoptlist{-mel -mel @gol
+@gccoptlist{-meb -mel @gol
+-mnhwloop @gol
+-muls @gol
-mmac @gol
--mscore5u -mscore7}
-
+-mscore5 -mscore5u -mscore7 -mscore7d}
+
@emph{SH Options}
@gccoptlist{-m1 -m2 -m2e -m3 -m3e @gol
-m4-nofpu -m4-single-only -m4-single -m4 @gol
@emph{VAX Options}
@gccoptlist{-mg -mgnu -munix}
+@emph{VxWorks Options}
+@gccoptlist{-mrtp -non-static -Bstatic -Bdynamic @gol
+-Xbind-lazy -Xbind-now}
+
@emph{x86-64 Options}
See i386 and x86-64 Options.
-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
Assembler code.
@item @var{file}.S
+@itemx @var{file}.sx
Assembler code which must be preprocessed.
@item @var{other}
@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
options understood by the compiler that fit into a specific class.
-The class can be one of @var{optimizers}, @var{warnings}, @var{target}
-or @var{params}:
+The class can be one of @samp{optimizers}, @samp{warnings}, @samp{target},
+@samp{params}, or @var{language}:
-@table @gcctabopt
-@item @var{optimizers}
+@table @asis
+@item @samp{optimizers}
This will display all of the optimization options supported by the
compiler.
-@item @var{warnings}
+@item @samp{warnings}
This will display all of the options controlling warning messages
produced by the compiler.
-@item @var{target}
+@item @samp{target}
This will display target-specific options. Unlike the
@option{--target-help} option however, target-specific options of the
linker and assembler will not be displayed. This is because those
tools do not currently support the extended @option{--help=} syntax.
-@item @var{params}
+@item @samp{params}
This will display the values recognized by the @option{--param}
option.
+
+@item @var{language}
+This will display the options supported for @var{language}, where
+@var{language} is the name of one of the languages supported in this
+version of GCC.
+
+@item @samp{common}
+This will display the options that are common to all languages.
@end table
It is possible to further refine the output of the @option{--help=}
option by adding a comma separated list of qualifiers after the
class. These can be any from the following list:
-@table @gcctabopt
-@item undocumented
+@table @asis
+@item @samp{undocumented}
Display only those options which are undocumented.
-@item joined
+@item @samp{joined}
Display options which take an argument that appears after an equal
sign in the same continuous piece of text, such as:
@samp{--help=target}.
-@item separate
+@item @samp{separate}
Display options which take an argument that appears as a separate word
following the original option, such as: @samp{-o output-file}.
@end table
@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
specifies the default behavior). This option was first supported in
GCC 4.3. This option is not supported in C89 or gnu89 mode.
-The preprocesor macros @code{__GNUC_GNU_INLINE__} and
+The preprocessor macros @code{__GNUC_GNU_INLINE__} and
@code{__GNUC_STDC_INLINE__} may be used to check which semantics are
in effect for @code{inline} functions. @xref{Common Predefined
Macros,,,cpp,The C Preprocessor}.
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
@opindex w
Inhibit all warning messages.
+@item -Wall
+@opindex Wall
+This enables all the warnings about constructions that some users
+consider questionable, and that are easy to avoid (or modify to
+prevent the warning), even in conjunction with macros. This also
+enables some language-specific warnings described in @ref{C++ Dialect
+Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
+
+@option{-Wall} turns on the following warning flags:
+
+@gccoptlist{-Waddress @gol
+-Warray-bounds @r{(only with} @option{-O2}@r{)} @gol
+-Wc++0x-compat @gol
+-Wchar-subscripts @gol
+-Wimplicit-int @gol
+-Wimplicit-function-declaration @gol
+-Wcomment @gol
+-Wformat @gol
+-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol
+-Wmissing-braces @gol
+-Wnonnull @gol
+-Wparentheses @gol
+-Wpointer-sign @gol
+-Wreorder @gol
+-Wreturn-type @gol
+-Wsequence-point @gol
+-Wsign-compare @r{(only in C++)} @gol
+-Wstrict-aliasing @gol
+-Wstrict-overflow @gol
+-Wswitch @gol
+-Wtrigraphs @gol
+-Wuninitialized @r{(only with} @option{-O1}@r{,} @option{-O2} @r{or} @option{-O3}@r{)} @gol
+-Wunknown-pragmas @gol
+-Wunused-function @gol
+-Wunused-label @gol
+-Wunused-value @gol
+-Wunused-variable @gol
+}
+
@item -Wno-import
@opindex Wno-import
Inhibit warning messages about the use of @samp{#import}.
values of objects take effect. Programs whose behavior depends on this
have undefined behavior; the C and C++ standards specify that ``Between
the previous and next sequence point an object shall have its stored
-value modified at most once by the evaluation of an expression.
+value modified at most once by the evaluation of an expression.
Furthermore, the prior value shall be read only to determine the value
to be stored.''. If a program breaks these rules, the results on any
particular implementation are entirely unpredictable.
@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 @option{-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}
-@opindex -Wstrict-overflow
+@opindex Wstrict-overflow
This option is only active when @option{-fstrict-overflow} is active.
It warns about cases where the compiler optimizes based on the
assumption that signed overflow does not occur. Note that it does not
overflow never does, in fact, occur. Therefore this warning can
easily give a false positive: a warning about code which is not
actually a problem. To help focus on important issues, several
-warning levels are defined.
+warning levels are defined. No warnings are issued for the use of
+undefined signed overflow when estimating how many iterations a loop
+will require, in particular when determining whether a loop will be
+executed at all.
-@table @option
+@table @gcctabopt
@item -Wstrict-overflow=1
Warn about cases which are both questionable and easy to avoid. For
example: @code{x + 1 > x}; with @option{-fstrict-overflow}, the
(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
-warnings about constructions that some users consider questionable, and
-that are easy to avoid (or modify to prevent the warning), even in
-conjunction with macros. This also enables some language-specific
-warnings described in @ref{C++ Dialect Options} and
-@ref{Objective-C and Objective-C++ Dialect Options}.
@end table
The following @option{-W@dots{}} options are not implied by @option{-Wall}.
@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
@option{-Wmissing-parameter-type}.
@item
-An empty body occurs in an @samp{if} or @samp{else} statement. This
-warning can be independently controlled by @option{-Wempty-body}.
+An empty body occurs in an @samp{if}, @samp{else} or
+@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{<=},
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 -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
+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
@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. 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} or @samp{else} 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
information about each symbol. This option only makes sense when
generating DWARF2 debugging information with @option{-gdwarf-2}.
+@item -femit-struct-debug-baseonly
+Emit debug information for struct-like types
+only when the base name of the compilation source file
+matches the base name of file in which the struct was defined.
+
+This option substantially reduces the size of debugging information,
+but at significant potential loss in type information to the debugger.
+See @option{-femit-struct-debug-reduced} for a less aggressive option.
+See @option{-femit-struct-debug-detailed} for more detailed control.
+
+This option works only with DWARF 2.
+
+@item -femit-struct-debug-reduced
+Emit debug information for struct-like types
+only when the base name of the compilation source file
+matches the base name of file in which the type was defined,
+unless the struct is a template or defined in a system header.
+
+This option significantly reduces the size of debugging information,
+with some potential loss in type information to the debugger.
+See @option{-femit-struct-debug-baseonly} for a more aggressive option.
+See @option{-femit-struct-debug-detailed} for more detailed control.
+
+This option works only with DWARF 2.
+
+@item -femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]}
+Specify the struct-like types
+for which the compiler will generate debug information.
+The intent is to reduce duplicate struct debug information
+between different object files within the same program.
+
+This option is a detailed version of
+@option{-femit-struct-debug-reduced} and @option{-femit-struct-debug-baseonly},
+which will serve for most needs.
+
+A specification has the syntax
+[@samp{dir:}|@samp{ind:}][@samp{ord:}|@samp{gen:}](@samp{any}|@samp{sys}|@samp{base}|@samp{none})
+
+The optional first word limits the specification to
+structs that are used directly (@samp{dir:}) or used indirectly (@samp{ind:}).
+A struct type is used directly when it is the type of a variable, member.
+Indirect uses arise through pointers to structs.
+That is, when use of an incomplete struct would be legal, the use is indirect.
+An example is
+@samp{struct one direct; struct two * indirect;}.
+
+The optional second word limits the specification to
+ordinary structs (@samp{ord:}) or generic structs (@samp{gen:}).
+Generic structs are a bit complicated to explain.
+For C++, these are non-explicit specializations of template classes,
+or non-template classes within the above.
+Other programming languages have generics,
+but @samp{-femit-struct-debug-detailed} does not yet implement them.
+
+The third word specifies the source files for those
+structs for which the compiler will emit debug information.
+The values @samp{none} and @samp{any} have the normal meaning.
+The value @samp{base} means that
+the base of name of the file in which the type declaration appears
+must match the base of the name of the main compilation file.
+In practice, this means that
+types declared in @file{foo.c} and @file{foo.h} will have debug information,
+but types declared in other header will not.
+The value @samp{sys} means those types satisfying @samp{base}
+or declared in system or compiler headers.
+
+You may need to experiment to determine the best settings for your application.
+
+The default is @samp{-femit-struct-debug-detailed=all}.
+
+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}.
@item sink
@opindex fdump-tree-sink
Dump each function after performing code sinking. The file name is made
-by appending @file{.sink} to the source file name.
+by appending @file{.sink} to the source file name.
@item dom
@opindex fdump-tree-dom
@item -ftree-vectorizer-verbose=@var{n}
@opindex ftree-vectorizer-verbose
This option controls the amount of debugging output the vectorizer prints.
-This information is written to standard error, unless
-@option{-fdump-tree-all} or @option{-fdump-tree-vect} is specified,
+This information is written to standard error, unless
+@option{-fdump-tree-all} or @option{-fdump-tree-vect} is specified,
in which case it is output to the usual dump listing file, @file{.vect}.
For @var{n}=0 no diagnostic information is reported.
-If @var{n}=1 the vectorizer reports each loop that got vectorized,
+If @var{n}=1 the vectorizer reports each loop that got vectorized,
and the total number of loops that got vectorized.
-If @var{n}=2 the vectorizer also reports non-vectorized loops that passed
-the first analysis phase (vect_analyze_loop_form) - i.e. countable,
-inner-most, single-bb, single-entry/exit loops. This is the same verbosity
+If @var{n}=2 the vectorizer also reports non-vectorized loops that passed
+the first analysis phase (vect_analyze_loop_form) - i.e. countable,
+inner-most, single-bb, single-entry/exit loops. This is the same verbosity
level that @option{-fdump-tree-vect-stats} uses.
-Higher verbosity levels mean either more information dumped for each
+Higher verbosity levels mean either more information dumped for each
reported loop, or same amount of information reported for more loops:
If @var{n}=3, alignment related information is added to the reports.
-If @var{n}=4, data-references related information (e.g. memory dependences,
+If @var{n}=4, data-references related information (e.g. memory dependences,
memory access-patterns) is added to the reports.
-If @var{n}=5, the vectorizer reports also non-vectorized inner-most loops
-that did not pass the first analysis phase (i.e. may not be countable, or
+If @var{n}=5, the vectorizer reports also non-vectorized inner-most loops
+that did not pass the first analysis phase (i.e. may not be countable, or
may have complicated control-flow).
If @var{n}=6, the vectorizer reports also non-vectorized nested loops.
-For @var{n}=7, all the information the vectorizer generates during its
+For @var{n}=7, all the information the vectorizer generates during its
analysis and transformation is reported. This is the same verbosity level
that @option{-fdump-tree-vect-details} uses.
-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,
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -fsplit-wide-types
-@opindex -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,
@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}.
Perform Full Redundancy Elimination (FRE) on trees. The difference
between FRE and PRE is that FRE only considers expressions
that are computed on all paths leading to the redundant computation.
-This analysis faster than PRE, though it exposes fewer redundancies.
+This analysis is faster than PRE, though it exposes fewer redundancies.
This flag is enabled by default at @option{-O} and higher.
@item -ftree-copy-prop
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
Perform induction variable optimizations (strength reduction, induction
variable merging and induction variable elimination) on trees.
+@item -ftree-parallelize-loops=n
+@opindex ftree-parallelize-loops=n
+Parallelize loops, i.e., split their iteration space to run in n threads.
+This is only possible for loops whose iterations are independent
+and can be arbitrarily reordered. The optimization is only
+profitable on multiprocessor machines, for loops that are CPU-intensive,
+rather than constrained e.g. by memory bandwidth.
+
@item -ftree-sra
Perform scalar replacement of aggregates. This pass replaces structure
references with scalars to prevent committing structures to memory too
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
@option{-funroll-loops},
@item -fsplit-ivs-in-unroller
-@opindex -fsplit-ivs-in-unroller
+@opindex fsplit-ivs-in-unroller
Enables expressing of values of induction variables in later iterations
of the unrolled loop using the value in the first iteration. This breaks
long dependency chains, thus improving efficiency of the scheduling passes.
This optimization is enabled by default.
@item -fvariable-expansion-in-unroller
-@opindex -fvariable-expansion-in-unroller
+@opindex fvariable-expansion-in-unroller
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
programs since the functions and variables become local for the whole combined
compilation unit, not for the single source file itself.
+This option is not supported for Fortran programs.
@item -fno-cprop-registers
@opindex fno-cprop-registers
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
-This option should never be turned on by any @option{-O} option since
+This option is not turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
an exact implementation of IEEE or ISO rules/specifications for
-math functions.
+math functions. It may, however, yield faster code for programs
+that do not require the guarantees of these specifications.
@item -fno-math-errno
@opindex fno-math-errno
IEEE exceptions for math error handling may want to use this flag
for speed while maintaining IEEE arithmetic compatibility.
-This option should never be turned on by any @option{-O} option since
+This option is not turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
an exact implementation of IEEE or ISO rules/specifications for
-math functions.
+math functions. It may, however, yield faster code for programs
+that do not require the guarantees of these specifications.
The default is @option{-fmath-errno}.
@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
or startup files that change the default FPU control word or other
similar optimizations.
-This option should never be turned on by any @option{-O} option since
+This option is not turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
an exact implementation of IEEE or ISO rules/specifications for
-math functions.
+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
that arguments and results are not NaNs or +-Infs.
-This option should never be turned on by any @option{-O} option since
+This option is not turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
-an exact implementation of IEEE or ISO rules/specifications.
+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.
The default is @option{-fno-finite-math-only}.
needed when performing complex division. The default is
@option{-fno-cx-limited-range}, but is enabled by @option{-ffast-math}.
-This option controls the default setting of the ISO C99
+This option controls the default setting of the ISO C99
@code{CX_LIMITED_RANGE} pragma. Nevertheless, the option applies to
all languages.
@opindex funroll-loops
Unroll loops whose number of iterations can be determined at compile time or
upon entry to the loop. @option{-funroll-loops} implies
-@option{-frerun-cse-after-loop}, @option{-fweb} and @option{-frename-registers}.
+@option{-frerun-cse-after-loop}, @option{-fweb} and @option{-frename-registers}.
It also turns on complete loop peeling (i.e.@: complete removal of loops with
small constant number of iterations). This option makes code larger, and may
or may not make it run faster.
@table @gcctabopt
@item salias-max-implicit-fields
The maximum number of fields in a variable without direct
-structure accesses for which structure aliasing will consider trying
+structure accesses for which structure aliasing will consider trying
to track each field. The default is 5
@item salias-max-array-elements
reduce function size by being inlined. In effect it increases amount of
inlining for code having large abstraction penalty (many functions that just
pass the arguments to other functions) and decrease inlining for code with low
-abstraction penalty. The default value is 16.
+abstraction penalty. The default value is 12.
@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
+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.
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
@item max-aliased-vops
-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.
+Maximum number of virtual operands per function allowed to represent
+aliases before triggering the alias partitioning heuristic. Alias
+partitioning reduces compile times and memory consumption needed for
+aliasing at the expense of precision loss in alias information. The
+default value for this parameter is 100 for -O1, 500 for -O2 and 1000
+for -O3.
+
+Notice that if a function contains more memory statements than the
+value of this parameter, it is not really possible to achieve this
+reduction. In this case, the compiler will use the number of memory
+statements as the value for @option{max-aliased-vops}.
+
+@item avg-aliased-vops
+
+Average number of virtual operands per statement allowed to represent
+aliases before triggering the alias partitioning heuristic. This
+works in conjunction with @option{max-aliased-vops}. If a function
+contains more than @option{max-aliased-vops} virtual operators, then
+memory symbols will be grouped into memory partitions until either the
+total number of virtual operators is below @option{max-aliased-vops}
+or the average number of virtual operators per memory statement is
+below @option{avg-aliased-vops}. The default value for this parameter
+is 1 for -O1 and -O2, and 3 for -O3.
@item ggc-min-expand
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 l2-cache-size
+The size of L2 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 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
Use @var{dir} as the logical root directory for headers and libraries.
For example, if the compiler would normally search for headers in
@file{/usr/include} and libraries in @file{/usr/lib}, it will instead
-search @file{@var{dir}/usr/include} and @file{@var{dir}/usr/lib}.
+search @file{@var{dir}/usr/include} and @file{@var{dir}/usr/lib}.
If you use both this option and the @option{-isysroot} option, then
the @option{--sysroot} option will apply to libraries, but the
%@{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}@}
@item %@{!.@code{S}:@code{X}@}
Substitutes @code{X}, if @emph{not} processing a file with suffix @code{S}.
+@item %@{,@code{S}:@code{X}@}
+Substitutes @code{X}, if processing a file for language @code{S}.
+
+@item %@{!,@code{S}:@code{X}@}
+Substitutes @code{X}, if not processing a file for language @code{S}.
+
@item %@{@code{S}|@code{P}:@code{X}@}
-Substitutes @code{X} if either @code{-S} or @code{-P} was given to GCC@.
-This may be combined with @samp{!}, @samp{.}, and @code{*} sequences as well,
-although they have a stronger binding than the @samp{|}. If @code{%*}
-appears in @code{X}, all of the alternatives must be starred, and only
-the first matching alternative is substituted.
+Substitutes @code{X} if either @code{-S} or @code{-P} was given to
+GCC@. This may be combined with @samp{!}, @samp{.}, @samp{,}, and
+@code{*} sequences as well, although they have a stronger binding than
+the @samp{|}. If @code{%*} appears in @code{X}, all of the
+alternatives must be starred, and only the first matching alternative
+is substituted.
For example, a spec string like this:
If @code{S} was given to GCC, substitutes @code{X}; else if @code{T} was
given to GCC, substitutes @code{Y}; else substitutes @code{D}. There can
be as many clauses as you need. This may be combined with @code{.},
-@code{!}, @code{|}, and @code{*} as needed.
+@code{,}, @code{!}, @code{|}, and @code{*} as needed.
@end table
arm-elf}, meaning to compile for an arm processor with elf binaries,
then you would specify @option{-b arm-elf} to run that cross compiler.
Because there are other options beginning with @option{-b}, the
-configuration must contain a hyphen.
+configuration must contain a hyphen.
@item -V @var{version}
@opindex V
* TMS320C3x/C4x Options::
* V850 Options::
* VAX Options::
+* VxWorks Options::
* x86-64 Options::
* Xstormy16 Options::
* Xtensa Options::
@cindex Blackfin Options
@table @gcctabopt
+@item -mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]}
+@opindex mcpu=
+Specifies the name of the target Blackfin processor. Currently, @var{cpu}
+can be one of @samp{bf522}, @samp{bf525}, @samp{bf527},
+@samp{bf531}, @samp{bf532}, @samp{bf533}, @samp{bf534},
+@samp{bf536}, @samp{bf537}, @samp{bf538}, @samp{bf539},
+@samp{bf542}, @samp{bf544}, @samp{bf548}, @samp{bf549},
+@samp{bf561}.
+The optional @var{sirevision} specifies the silicon revision of the target
+Blackfin processor. Any workarounds available for the targeted silicon revision
+will be enabled. If @var{sirevision} is @samp{none}, no workarounds are enabled.
+If @var{sirevision} is @samp{any}, all workarounds for the targeted processor
+will be enabled. The @code{__SILICON_REVISION__} macro is defined to two
+hexadecimal digits representing the major and minor numbers in the silicon
+revision. If @var{sirevision} is @samp{none}, the @code{__SILICON_REVISION__}
+is not defined. If @var{sirevision} is @samp{any}, the
+@code{__SILICON_REVISION__} is defined to be @code{0xffff}.
+If this optional @var{sirevision} is not used, GCC assumes the latest known
+silicon revision of the targeted Blackfin processor.
+
+Support for @samp{bf561} is incomplete. For @samp{bf561},
+Only the processor macro is defined.
+Without this option, @samp{bf532} is used as the processor by default.
+The corresponding predefined processor macros for @var{cpu} is to
+be defined. And for @samp{bfin-elf} toolchain, this causes the hardware BSP
+provided by libgloss to be linked in if @option{-msim} is not given.
+
+@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
@item -mspecld-anomaly
@opindex mspecld-anomaly
When enabled, the compiler will ensure that the generated code does not
-contain speculative loads after jump instructions. This option is enabled
-by default.
+contain speculative loads after jump instructions. If this option is used,
+@code{__WORKAROUND_SPECULATIVE_LOADS} is defined.
@item -mno-specld-anomaly
@opindex mno-specld-anomaly
@opindex mcsync-anomaly
When enabled, the compiler will ensure that the generated code does not
contain CSYNC or SSYNC instructions too soon after conditional branches.
-This option is enabled by default.
+If this option is used, @code{__WORKAROUND_SPECULATIVE_SYNCS} is defined.
@item -mno-csync-anomaly
@opindex mno-csync-anomaly
@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
@var{dir}. This option is valid only for the C family of languages.
@item -gused
-@opindex -gused
+@opindex gused
Emit debugging information for symbols that are used. For STABS
debugging format, this enables @option{-feliminate-unused-debug-symbols}.
This is by default ON@.
@item -gfull
-@opindex -gfull
+@opindex gfull
Emit debugging information for all symbols and types.
@item -mmacosx-version-min=@var{version}
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
@option{-mlong-branch} for PowerPC targets.
@item -mone-byte-bool
-@opindex -mone-byte-bool
+@opindex mone-byte-bool
Override the defaults for @samp{bool} so that @samp{sizeof(bool)==1}.
By default @samp{sizeof(bool)} is @samp{4} when compiling for
Darwin/PowerPC and @samp{1} when compiling for Darwin/x86, so this
output file being linked. See man ld(1) for more information.
@item -dynamiclib
-@opindex -dynamiclib
+@opindex dynamiclib
When passed this option, GCC will produce a dynamic library instead of
an executable when linking, using the Darwin @file{libtool} command.
@item -force_cpusubtype_ALL
-@opindex -force_cpusubtype_ALL
+@opindex force_cpusubtype_ALL
This causes GCC's output file to have the @var{ALL} subtype, instead of
one controlled by the @option{-mcpu} or @option{-march} option.
@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 amdfam10
-AMD Family 10 core based CPUs with x86-64 instruction set support. (This
+@item k8-sse3, opteron-sse3, athlon64-sse3
+Improved versions of k8, opteron and athlon64 with SSE3 instruction set support.
+@item amdfam10, barcelona
+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
@var{threshold} are placed in large data section. This value must be the
same across all object linked into the binary and defaults to 65535.
-@item -msvr3-shlib
-@itemx -mno-svr3-shlib
-@opindex msvr3-shlib
-@opindex mno-svr3-shlib
-Control whether GCC places uninitialized local variables into the
-@code{bss} or @code{data} segments. @option{-msvr3-shlib} places them
-into @code{bss}. These options are meaningful only on System V Release 3.
-
@item -mrtd
@opindex mrtd
Use a different function-calling convention, in which functions that
modules with the same value, including any libraries. This includes
the system libraries and startup modules.
+@item -mpc32
+@itemx -mpc64
+@itemx -mpc80
+@opindex mpc32
+@opindex mpc64
+@opindex mpc80
+
+Set 80387 floating-point precision to 32, 64 or 80 bits. When @option{-mpc32}
+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
Realign the stack at entry. On the Intel x86, the
@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 -msse5
+@itemx -mno-sse5
@item -m3dnow
@itemx -mno-3dnow
@item -mpopcnt
@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, SSE5, 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.
the file containing the CPU detection code should be compiled without
these options.
+@item -mcx16
+@opindex mcx16
+This option will enable GCC to use CMPXCHG16B instruction in generated code.
+CMPXCHG16B allows for atomic operations on 128-bit double quadword (or oword)
+data types. This is useful for high resolution counters that could be updated
+by multiple processors (or cores). This instruction is generated as part of
+atomic built-in functions: see @ref{Atomic Builtins} for details.
+
+@item -msahf
+@opindex msahf
+This option will enable GCC to use SAHF instruction in generated 64-bit code.
+Early Intel CPUs with Intel 64 lacked LAHF and SAHF instructions supported
+by AMD64 until introduction of Pentium 4 G1 step in December 2005. LAHF and
+SAHF are load and store instructions, respectively, for certain status flags.
+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
segment to cover the entire TLS area.
For systems that use GNU libc, the default is on.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+Enable automatic generation of fused floating point multiply-add instructions
+if the ISA supports such instructions. The -mfused-madd option is on by
+default. The fused multiply-add instructions have a different
+rounding behavior compared to executing a multiply followed by an add.
@end table
These @samp{-m} switches are supported in addition to the above
The 32-bit environment sets int, long and pointer to 32 bits and
generates code that runs on any i386 system.
The 64-bit environment sets int to 32 bits and long and pointer
-to 64 bits and generates code for AMD's x86-64 architecture.
+to 64 bits and generates code for AMD's x86-64 architecture. For
+darwin only the -m64 option turns off the @option{-fno-pic} and
+@option{-mdynamic-no-pic} options.
@item -mno-red-zone
@opindex no-red-zone
@item -mcmodel=large
@opindex mcmodel=large
Generate code for the large model: This model makes no assumptions
-about addresses and sizes of sections.
+about addresses and sizes of sections.
@end table
@node IA-64 Options
@item -mno-sched-br-data-spec
@itemx -msched-br-data-spec
-@opindex -mno-sched-br-data-spec
-@opindex -msched-br-data-spec
+@opindex mno-sched-br-data-spec
+@opindex msched-br-data-spec
(Dis/En)able data speculative scheduling before reload.
This will result in generation of the ld.a instructions and
the corresponding check instructions (ld.c / chk.a).
@item -msched-ar-data-spec
@itemx -mno-sched-ar-data-spec
-@opindex -msched-ar-data-spec
-@opindex -mno-sched-ar-data-spec
+@opindex msched-ar-data-spec
+@opindex mno-sched-ar-data-spec
(En/Dis)able data speculative scheduling after reload.
This will result in generation of the ld.a instructions and
the corresponding check instructions (ld.c / chk.a).
@item -mno-sched-control-spec
@itemx -msched-control-spec
-@opindex -mno-sched-control-spec
-@opindex -msched-control-spec
+@opindex mno-sched-control-spec
+@opindex msched-control-spec
(Dis/En)able control speculative scheduling. This feature is
available only during region scheduling (i.e. before reload).
This will result in generation of the ld.s instructions and
@item -msched-br-in-data-spec
@itemx -mno-sched-br-in-data-spec
-@opindex -msched-br-in-data-spec
-@opindex -mno-sched-br-in-data-spec
+@opindex msched-br-in-data-spec
+@opindex mno-sched-br-in-data-spec
(En/Dis)able speculative scheduling of the instructions that
are dependent on the data speculative loads before reload.
This is effective only with @option{-msched-br-data-spec} enabled.
@item -msched-ar-in-data-spec
@itemx -mno-sched-ar-in-data-spec
-@opindex -msched-ar-in-data-spec
-@opindex -mno-sched-ar-in-data-spec
+@opindex msched-ar-in-data-spec
+@opindex mno-sched-ar-in-data-spec
(En/Dis)able speculative scheduling of the instructions that
are dependent on the data speculative loads after reload.
This is effective only with @option{-msched-ar-data-spec} enabled.
@item -msched-in-control-spec
@itemx -mno-sched-in-control-spec
-@opindex -msched-in-control-spec
-@opindex -mno-sched-in-control-spec
+@opindex msched-in-control-spec
+@opindex mno-sched-in-control-spec
(En/Dis)able speculative scheduling of the instructions that
are dependent on the control speculative loads.
This is effective only with @option{-msched-control-spec} enabled.
@item -msched-ldc
@itemx -mno-sched-ldc
-@opindex -msched-ldc
-@opindex -mno-sched-ldc
+@opindex msched-ldc
+@opindex mno-sched-ldc
(En/Dis)able use of simple data speculation checks ld.c .
If disabled, only chk.a instructions will be emitted to check
data speculative loads.
@item -mno-sched-control-ldc
@itemx -msched-control-ldc
-@opindex -mno-sched-control-ldc
-@opindex -msched-control-ldc
+@opindex mno-sched-control-ldc
+@opindex msched-control-ldc
(Dis/En)able use of ld.c instructions to check control speculative loads.
If enabled, in case of control speculative load with no speculatively
scheduled dependent instructions this load will be emitted as ld.sa and
@item -mno-sched-spec-verbose
@itemx -msched-spec-verbose
-@opindex -mno-sched-spec-verbose
-@opindex -msched-spec-verbose
+@opindex mno-sched-spec-verbose
+@opindex msched-spec-verbose
(Dis/En)able printing of the information about speculative motions.
@item -mno-sched-prefer-non-data-spec-insns
@itemx -msched-prefer-non-data-spec-insns
-@opindex -mno-sched-prefer-non-data-spec-insns
-@opindex -msched-prefer-non-data-spec-insns
+@opindex mno-sched-prefer-non-data-spec-insns
+@opindex msched-prefer-non-data-spec-insns
If enabled, data speculative instructions will be chosen for schedule
only if there are no other choices at the moment. This will make
the use of the data speculation much more conservative.
@item -mno-sched-prefer-non-control-spec-insns
@itemx -msched-prefer-non-control-spec-insns
-@opindex -mno-sched-prefer-non-control-spec-insns
-@opindex -msched-prefer-non-control-spec-insns
+@opindex mno-sched-prefer-non-control-spec-insns
+@opindex msched-prefer-non-control-spec-insns
If enabled, control speculative instructions will be chosen for schedule
only if there are no other choices at the moment. This will make
the use of the control speculation much more conservative.
@item -mno-sched-count-spec-in-critical-path
@itemx -msched-count-spec-in-critical-path
-@opindex -mno-sched-count-spec-in-critical-path
-@opindex -msched-count-spec-in-critical-path
+@opindex mno-sched-count-spec-in-critical-path
+@opindex msched-count-spec-in-critical-path
If enabled, speculative dependencies will be considered during
computation of the instructions priorities. This will make the use of the
speculation a bit more conservative.
@multitable @columnfractions 0.20 0.80
@item @strong{Family} @tab @strong{@samp{-mcpu} arguments}
+@item @samp{51qe} @tab @samp{51qe}
@item @samp{5206} @tab @samp{5202} @samp{5204} @samp{5206}
@item @samp{5206e} @tab @samp{5206e}
@item @samp{5208} @tab @samp{5207} @samp{5208}
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}.
+are: @samp{cfv1}, @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.
16-bit boundary even on targets whose API mandates promotion to 32-bit.
@item -mno-short
-@opindex -mno-short
+@opindex mno-short
Do not consider type @code{int} to be 16 bits wide. This is the default.
@item -mnobitfield
@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{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 -minterlink-mips16
+@itemx -mno-interlink-mips16
+@opindex minterlink-mips16
+@opindex mno-interlink-mips16
+Require (do not require) that non-MIPS16 code be link-compatible with
+MIPS16 code.
+
+For example, non-MIPS16 code cannot jump directly to MIPS16 code;
+it must either use a call or an indirect jump. @option{-minterlink-mips16}
+therefore disables direct jumps unless GCC knows that the target of the
+jump is not MIPS16.
+
@item -mabi=32
@itemx -mabi=o64
@itemx -mabi=n32
Assume that the floating-point coprocessor only supports single-precision
operations.
-@itemx -mdouble-float
+@item -mdouble-float
@opindex mdouble-float
Assume that the floating-point coprocessor supports double-precision
operations. This is the default.
-@itemx -mdsp
+@item -mllsc
+@itemx -mno-llsc
+@opindex mllsc
+@opindex mno-llsc
+Use (do not use) @samp{ll}, @samp{sc}, and @samp{sync} instructions to
+implement atomic memory built-in functions. When neither option is
+specified, GCC will use the instructions if the target architecture
+supports them.
+
+@option{-mllsc} is useful if the runtime environment can emulate the
+instructions and @option{-mno-llsc} can be useful when compiling for
+nonstandard ISAs. You can make either option the default by
+configuring GCC with @option{--with-llsc} and @option{--without-llsc}
+respectively. @option{--with-llsc} is the default for some
+configurations; see the installation documentation for details.
+
+@item -mdsp
@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.
-@itemx -mdspr2
+@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}.
-
-@itemx -mpaired-single
+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
@opindex mpaired-single
@opindex mno-paired-single
when generating 64-bit code and requires hardware floating-point
support to be enabled.
-@itemx -mips3d
+@item -mdmx
+@itemx -mno-mdmx
+@opindex mdmx
+@opindex mno-mdmx
+Use (do not use) MIPS Digital Media Extension instructions.
+This option can only be used when generating 64-bit code and requires
+hardware floating-point support to be enabled.
+
+@item -mips3d
@itemx -mno-mips3d
@opindex mips3d
@opindex mno-mips3d
Use (do not use) the MIPS-3D ASE@. @xref{MIPS-3D Built-in Functions}.
The option @option{-mips3d} implies @option{-mpaired-single}.
+@item -mmt
+@itemx -mno-mt
+@opindex mmt
+@opindex mno-mt
+Use (do not use) MT Multithreading instructions.
+
@item -mlong64
@opindex mlong64
Force @code{long} types to be 64 bits wide. See @option{-mlong32} for
@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.
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 -mel
+@opindex mel
+Compile code for little endian mode.
+
+@item -mnhwloop
+@opindex mnhwloop
+Disable generate bcnz instruction.
+
+@item -muls
+@opindex muls
+Enable generate unaligned load and store instruction.
+
@item -mmac
@opindex mmac
Enable the use of multiply-accumulate instructions. Disabled by default.
+@item -mscore5
+@opindex mscore5
+Specify the SCORE5 as the target architecture.
+
@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.
+Specify the SCORE7 as the target architecture. This is the default.
+
+@item -mscore7d
+@opindex mscore7d
+Specify the SCORE7D as the target architecture.
@end table
@node SH Options
Output code for g-format floating point numbers instead of d-format.
@end table
+@node VxWorks Options
+@subsection VxWorks Options
+@cindex VxWorks Options
+
+The options in this section are defined for all VxWorks targets.
+Options specific to the target hardware are listed with the other
+options for that target.
+
+@table @gcctabopt
+@item -mrtp
+@opindex mrtp
+GCC can generate code for both VxWorks kernels and real time processes
+(RTPs). This option switches from the former to the latter. It also
+defines the preprocessor macro @code{__RTP__}.
+
+@item -non-static
+@opindex non-static
+Link an RTP executable against shared libraries rather than static
+libraries. The options @option{-static} and @option{-shared} can
+also be used for RTPs (@pxref{Link Options}); @option{-static}
+is the default.
+
+@item -Bstatic
+@itemx -Bdynamic
+@opindex Bstatic
+@opindex Bdynamic
+These options are passed down to the linker. They are defined for
+compatibility with Diab.
+
+@item -Xbind-lazy
+@opindex Xbind-lazy
+Enable lazy binding of function calls. This option is equivalent to
+@option{-Wl,-z,now} and is defined for compatibility with Diab.
+
+@item -Xbind-now
+@opindex Xbind-now
+Disable lazy binding of function calls. This option is the default and
+is defined for compatibility with Diab.
+@end table
+
@node x86-64 Options
@subsection x86-64 Options
@cindex x86-64 options
Usually these options are used when @option{-pie} GCC option will be
used during linking.
+@option{-fpie} and @option{-fPIE} both define the macros
+@code{__pie__} and @code{__PIE__}. The macros have the value 1
+for @option{-fpie} and 2 for @option{-fPIE}.
+
@item -fno-jump-tables
@opindex fno-jump-tables
Do not use jump tables for switch statements even where it would be
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
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. If a standard directory begins with the configured
-@var{prefix} then the value of @var{prefix} is replaced by
+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
OSDN Git Service
