@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+@c 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@ignore
@c man begin COPYRIGHT
Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997,
-1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 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}}. Use of the @command{gccbug}
-script to report bugs is recommended.
+@w{@uref{http://gcc.gnu.org/bugs.html}}.
@c man end
@c man begin AUTHOR
See the Info entry for @command{gcc}, or
-fno-default-inline -fvisibility-inlines-hidden @gol
-Wabi -Wctor-dtor-privacy @gol
-Wnon-virtual-dtor -Wreorder @gol
--Weffc++ -Wno-deprecated @gol
+-Weffc++ -Wno-deprecated -Wstrict-null-sentinel @gol
-Wno-non-template-friend -Wold-style-cast @gol
-Woverloaded-virtual -Wno-pmf-conversions @gol
--Wsign-promo -Wsynth}
+-Wsign-promo}
@item Objective-C and Objective-C++ Language Options
@xref{Objective-C and Objective-C++ Dialect Options,,Options Controlling
@item Language Independent Options
@xref{Language Independent Options,,Options to Control Diagnostic Messages Formatting}.
@gccoptlist{-fmessage-length=@var{n} @gol
--fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]}}
+-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]}} @gol
+-fdiagnostics-show-options
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
-w -Wextra -Wall -Waggregate-return @gol
-Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment @gol
-Wconversion -Wno-deprecated-declarations @gol
--Wdisabled-optimization -Wno-div-by-zero -Wendif-labels @gol
+-Wdisabled-optimization -Wno-div-by-zero -Wno-endif-labels @gol
-Werror -Werror-implicit-function-declaration @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-extra-args -Wformat-nonliteral @gol
-Wformat-security -Wformat-y2k @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
-Wimport -Wno-import -Winit-self -Winline @gol
+-Wno-int-to-pointer-cast @gol
-Wno-invalid-offsetof -Winvalid-pch @gol
-Wlarger-than-@var{len} -Wlong-long @gol
-Wmain -Wmissing-braces -Wmissing-field-initializers @gol
-Wmissing-format-attribute -Wmissing-include-dirs @gol
-Wmissing-noreturn @gol
-Wno-multichar -Wnonnull -Wpacked -Wpadded @gol
--Wparentheses -Wpointer-arith -Wredundant-decls @gol
+-Wparentheses -Wpointer-arith -Wno-pointer-to-int-cast @gol
+-Wredundant-decls @gol
-Wreturn-type -Wsequence-point -Wshadow @gol
-Wsign-compare -Wstrict-aliasing -Wstrict-aliasing=2 @gol
-Wswitch -Wswitch-default -Wswitch-enum @gol
@gccoptlist{-Wbad-function-cast -Wmissing-declarations @gol
-Wmissing-prototypes -Wnested-externs -Wold-style-definition @gol
-Wstrict-prototypes -Wtraditional @gol
--Wdeclaration-after-statement}
+-Wdeclaration-after-statement -Wno-pointer-sign}
@item Debugging Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
-fdump-tree-forwprop@r{[}-@var{n}@r{]} @gol
-fdump-tree-copyrename@r{[}-@var{n}@r{]} @gol
-fdump-tree-nrv -fdump-tree-vect @gol
+-fdump-tree-sink @gol
-fdump-tree-sra@r{[}-@var{n}@r{]} @gol
+-fdump-tree-salias @gol
-fdump-tree-fre@r{[}-@var{n}@r{]} @gol
+-ftree-vectorizer-verbose=@var{n} @gol
+-fdump-tree-storeccp@r{[}-@var{n}@r{]} @gol
-feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
-feliminate-unused-debug-symbols -fmem-report -fprofile-arcs -ftree-based-profiling @gol
-frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-fbounds-check -fmudflap -fmudflapth -fmudflapir @gol
-fbranch-probabilities -fprofile-values -fvpt -fbranch-target-load-optimize @gol
-fbranch-target-load-optimize2 -fbtr-bb-exclusive @gol
--fcaller-saves -fcprop-registers @gol
--fcse-follow-jumps -fcse-skip-blocks -fdata-sections @gol
+-fcaller-saves -fcprop-registers -fcse-follow-jumps @gol
+-fcse-skip-blocks -fcx-limited-range -fdata-sections @gol
-fdelayed-branch -fdelete-null-pointer-checks @gol
-fexpensive-optimizations -ffast-math -ffloat-store @gol
-fforce-addr -fforce-mem -ffunction-sections @gol
-floop-optimize -fcrossjumping -fif-conversion -fif-conversion2 @gol
-finline-functions -finline-limit=@var{n} -fkeep-inline-functions @gol
-fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
--fmodulo-sched -fnew-ra -fno-branch-count-reg @gol
+-fmodulo-sched -fno-branch-count-reg @gol
-fno-default-inline -fno-defer-pop -floop-optimize2 -fmove-loop-invariants @gol
-fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
-fvariable-expansion-in-unroller @gol
-ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize @gol
-ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts @gol
--ftree-dominator-opts -ftree-dse -ftree-copyrename @gol
+-ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink @gol
-ftree-ch -ftree-sra -ftree-ter -ftree-lrs -ftree-fre -ftree-vectorize @gol
+-ftree-salias -fweb @gol
+-ftree-copy-prop -ftree-store-ccp -ftree-store-copy-prop @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
@gccoptlist{-mmcu=@var{mcu} -msize -minit-stack=@var{n} -mno-interrupts @gol
-mcall-prologues -mno-tablejump -mtiny-stack -mint8}
+@emph{Blackfin Options}
+@gccoptlist{-momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer -mcsync @gol
+-mno-csync -mlow-64k -mno-low64k -mid-shared-library @gol
+-mno-id-shared-library -mshared-library-id=@var{n} @gol}
+
@emph{CRIS Options}
@gccoptlist{-mcpu=@var{cpu} -march=@var{cpu} -mtune=@var{cpu} @gol
-mmax-stack-frame=@var{n} -melinux-stacksize=@var{n} @gol
-mvliw-branch -mno-vliw-branch @gol
-mmulti-cond-exec -mno-multi-cond-exec -mnested-cond-exec @gol
-mno-nested-cond-exec -mtomcat-stats @gol
+-mTLS -mtls @gol
-mcpu=@var{cpu}}
@emph{H8/300 Options}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
--mvolatile-asm-stop -mb-step -mregister-names -mno-sdata @gol
+-mvolatile-asm-stop -mregister-names -mno-sdata @gol
-mconstant-gp -mauto-pic -minline-float-divide-min-latency @gol
-minline-float-divide-max-throughput @gol
-minline-int-divide-min-latency @gol
-mxgot -mno-xgot -mgp32 -mgp64 -mfp32 -mfp64 @gol
-mhard-float -msoft-float -msingle-float -mdouble-float @gol
-mpaired-single -mips3d @gol
--mint64 -mlong64 -mlong32 @gol
+-mint64 -mlong64 -mlong32 -msym32 -mno-sym32 @gol
-G@var{num} -membedded-data -mno-embedded-data @gol
-muninit-const-in-rodata -mno-uninit-const-in-rodata @gol
-msplit-addresses -mno-split-addresses @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-sb1 -mno-fix-sb1 @gol
+-mfix-vr4120 -mno-fix-vr4120 -mfix-vr4130 @gol
+-mfix-sb1 -mno-fix-sb1 @gol
-mflush-func=@var{func} -mno-flush-func @gol
-mbranch-likely -mno-branch-likely @gol
-mfp-exceptions -mno-fp-exceptions @gol
-mpowerpc-gfxopt -mno-powerpc-gfxopt @gol
-mnew-mnemonics -mold-mnemonics @gol
-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc @gol
--m64 -m32 -mxl-call -mno-xl-call -mpe @gol
+-m64 -m32 -mxl-compat -mno-xl-compat -mpe @gol
-malign-power -malign-natural @gol
-msoft-float -mhard-float -mmultiple -mno-multiple @gol
-mstring -mno-string -mupdate -mno-update @gol
@opindex Wno-deprecated
Do not warn about usage of deprecated features. @xref{Deprecated Features}.
+@item -Wstrict-null-sentinel @r{(C++ only)}
+@opindex Wstrict-null-sentinel
+Warn also about the use of an uncasted @code{NULL} as sentinel. When
+compiling only with GCC this is a valid sentinel, as @code{NULL} is defined
+to @code{__null}. Although it is a null pointer constant not a null pointer,
+it is guaranteed to of the same size as a pointer. But this use is
+not portable across different compilers.
+
@item -Wno-non-template-friend @r{(C++ only)}
@opindex Wno-non-template-friend
Disable warnings when non-templatized friend functions are declared
the same size. Previous versions of G++ would try to preserve
unsignedness, but the standard mandates the current behavior.
-@item -Wsynth @r{(C++ only)}
-@opindex Wsynth
-@cindex warning for synthesized methods
-@cindex synthesized methods, warning
-Warn when G++'s synthesis behavior does not match that of cfront. For
-instance:
-
@smallexample
struct A @{
operator int ();
prefix) for physical lines that result from the process of breaking
a message which is too long to fit on a single line.
+@item -fdiagnostics-show-options
+@opindex fdiagnostics-show-options
+This option instructs the diagnostic machinery to add text to each
+diagnostic emitted, which indicates which command line option directly
+controls that diagnostic, when such an option is known to the
+diagnostic machinery.
+
@end table
@node Warning Options
Warn if an array subscript has type @code{char}. This is a common cause
of error, as programmers often forget that this type is signed on some
machines.
+This warning is enabled by @option{-Wall}.
@item -Wcomment
@opindex Wcomment
Warn whenever a comment-start sequence @samp{/*} appears in a @samp{/*}
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
+This warning is enabled by @option{-Wall}.
@item -Wfatal-errors
@opindex Wfatal-errors
@item -Wimplicit-int
@opindex Wimplicit-int
Warn when a declaration does not specify a type.
+This warning is enabled by @option{-Wall}.
@item -Wimplicit-function-declaration
@itemx -Werror-implicit-function-declaration
Give a warning (or error) whenever a function is used before being
declared. The form @option{-Wno-error-implicit-function-declaration}
is not supported.
+This warning is enabled by @option{-Wall} (as a warning, not an error).
@item -Wimplicit
@opindex Wimplicit
Same as @option{-Wimplicit-int} and @option{-Wimplicit-function-declaration}.
+This warning is enabled by @option{-Wall}.
@item -Wmain
@opindex Wmain
Warn if the type of @samp{main} is suspicious. @samp{main} should be a
function with external linkage, returning int, taking either zero
arguments, two, or three arguments of appropriate types.
+This warning is enabled by @option{-Wall}.
@item -Wmissing-braces
@opindex Wmissing-braces
int b[2][2] = @{ @{ 0, 1 @}, @{ 2, 3 @} @};
@end smallexample
+This warning is enabled by @option{-Wall}.
+
@item -Wmissing-include-dirs @r{(C, C++, Objective-C and Objective-C++ only)}
@opindex Wmissing-include-dirs
Warn if a user-supplied include directory does not exist.
@end group
@end smallexample
+This warning is enabled by @option{-Wall}.
+
@item -Wsequence-point
@opindex Wsequence-point
Warn about code that may have undefined semantics because of violations
definitions, may be found on the GCC readings page, at
@w{@uref{http://gcc.gnu.org/readings.html}}.
+This warning is enabled by @option{-Wall}.
+
@item -Wreturn-type
@opindex Wreturn-type
Warn whenever a function is defined with a return-type that defaults to
message, even when @option{-Wno-return-type} is specified. The only
exceptions are @samp{main} and functions defined in system headers.
+This warning is enabled by @option{-Wall}.
+
@item -Wswitch
@opindex Wswitch
Warn whenever a @code{switch} statement has an index of enumerated type
enumeration. (The presence of a @code{default} label prevents this
warning.) @code{case} labels outside the enumeration range also
provoke warnings when this option is used.
+This warning is enabled by @option{-Wall}.
@item -Wswitch-default
@opindex Wswitch-switch
@opindex Wtrigraphs
Warn if any trigraphs are encountered that might change the meaning of
the program (trigraphs within comments are not warned about).
+This warning is enabled by @option{-Wall}.
@item -Wunused-function
@opindex Wunused-function
Warn whenever a static function is declared but not defined or a
non\-inline static function is unused.
+This warning is enabled by @option{-Wall}.
@item -Wunused-label
@opindex Wunused-label
Warn whenever a label is declared but not used.
+This warning is enabled by @option{-Wall}.
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
@opindex Wunused-variable
Warn whenever a local variable or non-constant static variable is unused
aside from its declaration
+This warning is enabled by @option{-Wall}.
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
@item -Wunused-value
@opindex Wunused-value
Warn whenever a statement computes a result that is explicitly not used.
+This warning is enabled by @option{-Wall}.
To suppress this warning cast the expression to @samp{void}.
you use that never return as @code{noreturn}. @xref{Function
Attributes}.
+This warning is enabled by @option{-Wall}.
+
@item -Wunknown-pragmas
@opindex Wunknown-pragmas
@cindex warning for unknown pragmas
@opindex Wundef
Warn if an undefined identifier is evaluated in an @samp{#if} directive.
-@item -Wendif-labels
+@item -Wno-endif-labels
+@opindex Wno-endif-labels
@opindex Wendif-labels
-Warn whenever an @samp{#else} or an @samp{#endif} are followed by text.
+Do not warn whenever an @samp{#else} or an @samp{#endif} are followed by text.
@item -Wshadow
@opindex Wshadow
Usually they indicate a typo in the user's code, as they have
implementation-defined values, and should not be used in portable code.
+@item -Wnormalized=<none|id|nfc|nfkc>
+@opindex Wnormalized
+@cindex NFC
+@cindex NFKC
+@cindex character set, input normalization
+In ISO C and ISO C++, two identifiers are different if they are
+different sequences of characters. However, sometimes when characters
+outside the basic ASCII character set are used, you can have two
+different character sequences that look the same. To avoid confusion,
+the ISO 10646 standard sets out some @dfn{normalization rules} which
+when applied ensure that two sequences that look the same are turned into
+the same sequence. GCC can warn you if you are using identifiers which
+have not been normalized; this option controls that warning.
+
+There are four levels of warning that GCC supports. The default is
+@option{-Wnormalized=nfc}, which warns about any identifier which is
+not in the ISO 10646 ``C'' normalized form, @dfn{NFC}. NFC is the
+recommended form for most uses.
+
+Unfortunately, there are some characters which ISO C and ISO C++ allow
+in identifiers that when turned into NFC aren't allowable as
+identifiers. That is, there's no way to use these symbols in portable
+ISO C or C++ and have all your identifiers in NFC.
+@option{-Wnormalized=id} suppresses the warning for these characters.
+It is hoped that future versions of the standards involved will correct
+this, which is why this option is not the default.
+
+You can switch the warning off for all characters by writing
+@option{-Wnormalized=none}. You would only want to do this if you
+were using some other normalization scheme (like ``D''), because
+otherwise you can easily create bugs that are literally impossible to see.
+
+Some characters in ISO 10646 have distinct meanings but look identical
+in some fonts or display methodologies, especially once formatting has
+been applied. For instance @code{\u207F}, ``SUPERSCRIPT LATIN SMALL
+LETTER N'', will display just like a regular @code{n} which has been
+placed in a superscript. ISO 10646 defines the @dfn{NFKC}
+normalisation scheme to convert all these into a standard form as
+well, and GCC will warn if your code is not in NFKC if you use
+@option{-Wnormalized=nfkc}. This warning is comparable to warning
+about every identifier that contains the letter O because it might be
+confused with the digit 0, and so is not the default, but may be
+useful as a local coding convention if the programming environment is
+unable to be fixed to display these characters distinctly.
+
@item -Wno-deprecated-declarations
@opindex Wno-deprecated-declarations
Do not warn about uses of functions, variables, and types marked as
The compiler uses a variety of heuristics to determine whether or not
to inline a function. For example, the compiler takes into account
-the size of the function being inlined and the the amount of inlining
+the size of the function being inlined and the amount of inlining
that has already been done in the current function. Therefore,
seemingly insignificant changes in the source program can cause the
warnings produced by @option{-Winline} to appear or disappear.
The restrictions on @samp{offsetof} may be relaxed in a future version
of the C++ standard.
+@item -Wno-int-to-pointer-cast @r{(C only)}
+@opindex Wno-int-to-pointer-cast
+Suppress warnings from casts to pointer type of an integer of a
+different size.
+
+@item -Wno-pointer-to-int-cast @r{(C only)}
+@opindex Wno-pointer-to-int-cast
+Suppress warnings from casts from a pointer to an integer type of a
+different size.
+
@item -Winvalid-pch
@opindex Winvalid-pch
Warn if a precompiled header (@pxref{Precompiled Headers}) is found in
complex; GCC will refuse to optimize programs when the optimization
itself is likely to take inordinate amounts of time.
+@item -Wno-pointer-sign
+@opindex Wno-pointer-sign
+Don't warn for pointer argument passing or assignment with different signedness.
+Only useful in the negative form since this warning is enabled by default.
+This option is only supported for C and Objective-C@.
+
@item -Werror
@opindex Werror
Make all warnings into errors.
(e.g.@: @file{foo.gcda} for input file @file{dir/foo.c}, or
@file{dir/foo.gcda} for output file specified as @option{-o dir/foo.o}).
+@cindex @command{gcov}
+@item --coverage
+@opindex coverage
+
+This option is used to compile and link code instrumented for coverage
+analysis. The option is a synonym for @option{-fprofile-arcs}
+@option{-ftest-coverage} (when compiling) and @option{-lgcov} (when
+linking). See the documentation for those options for more details.
+
@itemize
@item
@opindex fdump-rtl-btl
@opindex fdump-rtl-dbr
@option{-dd} and @option{-fdump-rtl-btl} enable dumping after branch
-target load optimization, to to @file{@var{file}.31.btl}. @option{-dd}
+target load optimization, to @file{@var{file}.31.btl}. @option{-dd}
and @option{-fdump-rtl-dbr} enable dumping after delayed branch
scheduling, to @file{@var{file}.36.dbr}.
Dump SSA related information to a file. The file name is made by appending
@file{.ssa} to the source file name.
+@item salias
+@opindex fdump-tree-salias
+Dump structure aliasing variable information to a file. This file name
+is made by appending @file{.salias} to the source file name.
+
@item alias
@opindex fdump-tree-alias
Dump aliasing information for each function. The file name is made by
Dump each function after CCP@. The file name is made by appending
@file{.ccp} to the source file name.
+@item storeccp
+@opindex fdump-tree-storeccp
+Dump each function after STORE-CCP. The file name is made by appending
+@file{.storeccp} to the source file name.
+
@item pre
@opindex fdump-tree-pre
Dump trees after partial redundancy elimination. The file name is made
Dump trees after full redundancy elimination. The file name is made
by appending @file{.fre} to the source file name.
+@item copyprop
+@opindex fdump-tree-copyprop
+Dump trees after copy propagation. The file name is made
+by appending @file{.copyprop} to the source file name.
+
+@item store_copyprop
+@opindex fdump-tree-store_copyprop
+Dump trees after store copy-propagation. The file name is made
+by appending @file{.store_copyprop} to the source file name.
+
@item dce
@opindex fdump-tree-dce
Dump each function after dead code elimination. The file name is made by
Dump each function after performing scalar replacement of aggregates. The
file name is made by appending @file{.sra} to the source file name.
+@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.
+
@item dom
@opindex fdump-tree-dom
Dump each function after applying dominator tree optimizations. The file
Enable all the available tree dumps with the flags provided in this option.
@end table
+@item -ftree-vectorizer-verbose=@var{n}
+@opindex ftree-vectorizer-verbose
+This option controls the amount of debugging output the vectorizer prints.
+This information is written to standard error, unless @option{-fdump-tree-all}
+or @option{-fdump-tree-vect} is specified, in which case it is output to the
+usual dump listing file, @file{.vect}.
+
@item -frandom-seed=@var{string}
@opindex frandom-string
This option provides a seed that GCC uses when it would otherwise use
@option{-O} turns on the following optimization flags:
@gccoptlist{-fdefer-pop @gol
--fmerge-constants @gol
--fthread-jumps @gol
+-fdelayed-branch @gol
+-fguess-branch-probability @gol
+-fcprop-registers @gol
-floop-optimize @gol
-fif-conversion @gol
-fif-conversion2 @gol
--fdelayed-branch @gol
--fguess-branch-probability @gol
--fcprop-registers}
+-ftree-ccp @gol
+-ftree-dce @gol
+-ftree-dominator-opts @gol
+-ftree-dse @gol
+-ftree-ter @gol
+-ftree-lrs @gol
+-ftree-sra @gol
+-ftree-copyrename @gol
+-ftree-fre @gol
+-ftree-ch @gol
+-fmerge-constants}
@option{-O} also turns on @option{-fomit-frame-pointer} on machines
where doing so does not interfere with debugging.
@option{-O2} turns on all optimization flags specified by @option{-O}. It
also turns on the following optimization flags:
-@gccoptlist{-fforce-mem @gol
+@gccoptlist{-fthread-jumps @gol
+-fcrossjumping @gol
-foptimize-sibling-calls @gol
--fstrength-reduce @gol
-fcse-follow-jumps -fcse-skip-blocks @gol
--frerun-cse-after-loop -frerun-loop-opt @gol
--fgcse -fgcse-lm -fgcse-sm -fgcse-las @gol
--fdelete-null-pointer-checks @gol
+-fgcse -fgcse-lm @gol
-fexpensive-optimizations @gol
--fregmove @gol
--fschedule-insns -fschedule-insns2 @gol
--fsched-interblock -fsched-spec @gol
+-fstrength-reduce @gol
+-frerun-cse-after-loop -frerun-loop-opt @gol
-fcaller-saves @gol
+-fforce-mem @gol
-fpeephole2 @gol
--freorder-blocks -freorder-functions @gol
+-fschedule-insns -fschedule-insns2 @gol
+-fsched-interblock -fsched-spec @gol
+-fregmove @gol
-fstrict-aliasing @gol
+-fdelete-null-pointer-checks @gol
+-freorder-blocks -freorder-functions @gol
-funit-at-a-time @gol
-falign-functions -falign-jumps @gol
-falign-loops -falign-labels @gol
--fcrossjumping}
+-ftree-pre}
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
@opindex O3
Optimize yet more. @option{-O3} turns on all optimizations specified by
@option{-O2} and also turns on the @option{-finline-functions},
-@option{-fweb} and @option{-fgcse-after-reload} options.
+@option{-funswitch-loops} and @option{-fgcse-after-reload} options.
@item -O0
@opindex O0
pass. This pass looks at innermost loops and reorders their
instructions by overlapping different iterations.
-@item -fnew-ra
-@opindex fnew-ra
-Use a graph coloring register allocator. Currently this option is meant
-only for testing. Users should not specify this option, since it is not
-yet ready for production use.
-
@item -fno-branch-count-reg
@opindex fno-branch-count-reg
Do not use ``decrement and branch'' instructions on a count register,
second branch or a point immediately following it, depending on whether
the condition is known to be true or false.
-Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -fcse-follow-jumps
@opindex fcse-follow-jumps
loops containing a load/store sequence can be changed to a load before
the loop and a store after the loop.
-Enabled by default when gcse is enabled.
+Not enabled at any optimization level.
@item -fgcse-las
@opindex fgcse-las
elimination pass eliminates redundant loads that come after stores to the
same memory location (both partial and full redundancies).
-Enabled by default when gcse is enabled.
+Not enabled at any optimization level.
@item -fgcse-after-reload
@opindex fgcse-after-reload
@item -ftree-pre
Perform Partial Redundancy Elimination (PRE) on trees. This flag is
-enabled by default at @option{-O} and higher.
+enabled by default at @option{-O2} and @option{-O3}.
@item -ftree-fre
Perform Full Redundancy Elimination (FRE) on trees. The difference
This analysis faster than PRE, though it exposes fewer redundancies.
This flag is enabled by default at @option{-O} and higher.
-@item -ftree-ccp
-Perform sparse conditional constant propagation (CCP) on trees. This flag
+@item -ftree-copy-prop
+Perform copy propagation on trees. This pass eliminates unnecessary
+copy operations. This flag is enabled by default at @option{-O} and
+higher.
+
+@item -ftree-store-copy-prop
+Perform copy propagation of memory loads and stores. This pass
+eliminates unnecessary copy operations in memory references
+(structures, global variables, arrays, etc). This flag is enabled by
+default at @option{-O2} and higher.
+
+@item -ftree-salias
+Perform structural alias analysis on trees. This flag
is enabled by default at @option{-O} and higher.
+@item -ftree-sink
+Perform forward store motion on trees. This flag is
+enabled by default at @option{-O} and higher.
+
+@item -ftree-ccp
+Perform sparse conditional constant propagation (CCP) on trees. This
+pass only operates on local scalar variables and is enabled by default
+at @option{-O} and higher.
+
+@item -ftree-store-ccp
+Perform sparse conditional constant propagation (CCP) on trees. This
+pass operates on both local scalar variables and memory stores and
+loads (global variables, structures, arrays, etc). This flag is
+enabled by default at @option{-O2} and higher.
+
@item -ftree-dce
Perform dead code elimination (DCE) on trees. This flag is enabled by
default at @option{-O} and higher.
Perform linear loop transformations on tree. This flag can improve cache
performance and allow further loop optimizations to take place.
-@item -ftree-lim
-Perform loop invariant motion on trees. This pass moves only invartiants that
-would be hard to handle on rtl level (function calls, operations that expand to
+@item -ftree-loop-im
+Perform loop invariant motion on trees. This pass moves only invariants that
+would be hard to handle at RTL level (function calls, operations that expand to
nontrivial sequences of insns). With @option{-funswitch-loops} it also moves
operands of conditions that are invariant out of the loop, so that we can use
just trivial invariantness analysis in loop unswitching. The pass also includes
store motion.
-@item -fivcanon
+@item -ftree-loop-ivcanon
Create a canonical counter for number of iterations in the loop for that
determining number of iterations requires complicated analysis. Later
optimizations then may determine the number easily. Useful especially
@item -freorder-functions
@opindex freorder-functions
-Reorder basic blocks in the compiled function in order to reduce number of
-taken branches and improve code locality. This is implemented by using special
+Reorder functions in the object file in order to
+improve code locality. This is implemented by using special
subsections @code{.text.hot} for most frequently executed functions and
@code{.text.unlikely} for unlikely executed functions. Reordering is done by
the linker so object file format must support named sections and linker must
@opindex ffast-math
Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @*
@option{-fno-trapping-math}, @option{-ffinite-math-only},
-@option{-fno-rounding-math} and @option{-fno-signaling-nans}.
+@option{-fno-rounding-math}, @option{-fno-signaling-nans}
+and @option{fcx-limited-range}.
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
Treat floating point constant as single precision constant instead of
implicitly converting it to double precision constant.
+@item -fcx-limited-range
+@itemx -fno-cx-limited-range
+@opindex fcx-limited-range
+@opindex fno-cx-limited-range
+When enabled, this option states that a range reduction step is not
+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
+@code{CX_LIMITED_RANGE} pragma. Nevertheless, the option applies to
+all languages.
@end table
Not enabled by default at any level because it has known bugs.
-@item -fnew-ra
-@opindex fnew-ra
-Use a graph coloring register allocator. Currently this option is meant
-for testing, so we are interested to hear about miscompilations with
-@option{-fnew-ra}.
-
@item -ftracer
@opindex ftracer
Perform tail duplication to enlarge superblock size. This transformation
@var{name} are given in the following table:
@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
+to track each field. The default is 5
+
@item sra-max-structure-size
The maximum structure size, in bytes, at which the scalar replacement
of aggregates (SRA) optimization will perform block copies. The
value is ignored in the case where all instructions in the block being
crossjumped from are matched. The default value is 5.
+@item max-goto-duplication-insns
+The maximum number of instructions to duplicate to a block that jumps
+to a computed goto. To avoid @math{O(N^2)} behavior in a number of
+passes, GCC factors computed gotos early in the compilation process,
+and unfactors them as late as possible. Only computed jumps at the
+end of a basic blocks with no more than max-goto-duplication-insns are
+unfactored. The default value is 8.
+
@item max-delay-slot-insn-search
The maximum number of instructions to consider when looking for an
instruction to fill a delay slot. If more than this arbitrary number of
internal representation) in a single function that the tree inliner
will consider for inlining. This only affects functions declared
inline and methods implemented in a class declaration (C++).
-The default value is 500.
+The default value is 450.
@item max-inline-insns-auto
When you use @option{-finline-functions} (included in @option{-O3}),
by the compiler will be investigated. To those functions, a different
(more restrictive) limit compared to functions declared inline can
be applied.
-The default value is 120.
+The default value is 90.
@item large-function-insns
The limit specifying really large functions. For functions larger than this
to avoid extreme compilation time caused by non-linear algorithms used by the
backend.
This parameter is ignored when @option{-funit-at-a-time} is not used.
-The default value is 3000.
+The default value is 2700.
@item large-function-growth
Specifies maximal growth of large function caused by inlining in percents.
taken into acount. For function not declared inline, recursive inlining
happens only when @option{-finline-functions} (included in @option{-O3}) is
enabled and @option{--param max-inline-insns-recursive-auto} is used. The
-default value is 500.
+default value is 450.
@item max-inline-recursive-depth
@itemx max-inline-recursive-depth-auto
taken into acount. For function not declared inline, recursive inlining
happens only when @option{-finline-functions} (included in @option{-O3}) is
enabled and @option{--param max-inline-recursive-depth-auto} is used. The
-default value is 500.
+default value is 450.
+
+@item inline-call-cost
+Specify cost of call instruction relative to simple arithmetics operations
+(having cost of 1). Increasing this cost disqualifies inlining of non-leaf
+functions and at the same time increases size of leaf function that is believed to
+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.
@item max-unrolled-insns
The maximum number of instructions that a loop should have if that loop
we always try to remove unnecessary ivs from the set during its
optimization when a new iv is added to the set.
+@item scev-max-expr-size
+Bound on size of expressions used in the scalar evolutions analyzer.
+Large expressions slow the analyzer.
+
@item max-iterations-to-track
The maximum number of iterations of a loop the brute force algorithm
The maximum number of insns in a region to be considered for
interblock scheduling. The default value is 100.
+@item max-last-value-rtl
+
+The maximum size measured as number of RTLs that can be recorded in an expression
+in combiner for a pseudo register as last known value of that register. The default
+is 10000.
+
@item integer-share-limit
Small integer constants can use a shared data structure, reducing the
compiler's memory usage and increasing its speed. This sets the maximum
value of a shared integer constant's. The default value is 256.
+@item min-virtual-mappings
+Specifies the minimum number of virtual mappings in the incremental
+SSA updater that should be registered to trigger the virtual mappings
+heuristic defined by virtual-mappings-ratio. The default value is
+100.
+
+@item virtual-mappings-ratio
+If the number of virtual mappings is virtual-mappings-ratio bigger
+than the number of virtual symbols to be updated, then the incremental
+SSA updater switches to a full update for those symbols. The default
+ratio is 3.
+
@end table
@end table
contain startup files. If the target supports multilibs then the
current multilib directory will be prepended to each of these paths.
-@item %M
-Output the multilib directory with directory separators replaced with
-@samp{_}. If multilib directories are not set, or the multilib directory is
-@file{.} then this option emits nothing.
-
@item %L
Process the @code{lib} spec. This is a spec string for deciding which
libraries should be included on the command line to the linker.
* ARC Options::
* ARM Options::
* AVR Options::
+* Blackfin Options::
* CRIS Options::
* Darwin Options::
* DEC Alpha Options::
size.
@end table
+@node Blackfin Options
+@subsection Blackfin Options
+@cindex Blackfin Options
+
+@table @gcctabopt
+@item -momit-leaf-frame-pointer
+@opindex momit-leaf-frame-pointer
+Don't keep the frame pointer in a register for leaf functions. This
+avoids the instructions to save, set up and restore frame pointers and
+makes an extra register available in leaf functions. The option
+@option{-fomit-frame-pointer} removes the frame pointer for all functions
+which might make debugging harder.
+
+@item -mcsync
+@opindex mcsync
+When enabled, the compiler will ensure that the generated code does not
+contain speculative loads after jump instructions. This option is enabled
+by default.
+
+@item -mno-csync
+@opindex mno-csync
+Don't generate extra code to prevent speculative loads from occurring.
+
+@item -mlow-64k
+@opindex mlow-64k
+When enabled, the compiler is free to take advantage of the knowledge that
+the entire program fits into the low 64k of memory.
+
+@item -mno-low-64k
+@opindex mno-low-64k
+Assume that the program is arbitrarily large. This is the default.
+
+@item -mid-shared-library
+@opindex mid-shared-library
+Generate code that supports shared libraries via the library ID method.
+This allows for execute in place and shared libraries in an environment
+without virtual memory management. This option implies @option{-fPIC}.
+
+@item -mno-id-shared-library
+@opindex mno-id-shared-library
+Generate code that doesn't assume ID based shared libraries are being used.
+This is the default.
+
+@item -mshared-library-id=n
+@opindex mshared-library-id
+Specified the identification number of the ID based shared library being
+compiled. Specifying a value of 0 will generate more compact code, specifying
+other values will force the allocation of that number to the current
+library but is no more space or time efficient than omitting this option.
+@end table
+
@node CRIS Options
@subsection CRIS Options
@cindex CRIS Options
that GCC is targetting, like @option{-mcpu} or @option{-march}. The
@option{-force_cpusubtype_ALL} option can be used to override this.
-The Darwin tools vary in their behaviour when presented with an ISA
+The Darwin tools vary in their behavior when presented with an ISA
mismatch. The assembler, @file{as}, will only permit instructions to
be used that are valid for the subtype of the file it is generating,
so you cannot put 64-bit instructions in an @samp{ppc750} object file.
optimization option such as @option{-O3} or above is present in the
command line.
+@item -mTLS
+@opindex TLS
+
+Assume a large TLS segment when generating thread-local code.
+
+@item -mtls
+@opindex tls
+
+Do not assume a large TLS segment when generating thread-local code.
+
@item -mgprel-ro
@opindex mgprel-ro
only in Pentium4 and the future AMD x86-64 chips supports double precision
arithmetics too.
-For i387 you need to use @option{-march=@var{cpu-type}}, @option{-msse} or
-@option{-msse2} switches to enable SSE extensions and make this option
-effective. For x86-64 compiler, these extensions are enabled by default.
+For the i386 compiler, you need to use @option{-march=@var{cpu-type}}, @option{-msse}
+or @option{-msse2} switches to enable SSE extensions and make this option
+effective. For the x86-64 compiler, these extensions are enabled by default.
The resulting code should be considerably faster in the majority of cases and avoid
the numerical instability problems of 387 code, but may break some existing
Generate (or don't) a stop bit immediately before and after volatile asm
statements.
-@item -mb-step
-@opindex mb-step
-Generate code that works around Itanium B step errata.
-
@item -mregister-names
@itemx -mno-register-names
@opindex mregister-names
@option{-mlong32} for an explanation of the default and the way
that the pointer size is determined.
+This option has been deprecated and will be removed in a future release.
+
@item -mlong64
@opindex mlong64
Force @code{long} types to be 64 bits wide. See @option{-mlong32} for
32-bit @code{long}s. Pointers are the same size as @code{long}s,
or the same size as integer registers, whichever is smaller.
+@item -msym32
+@itemx -mno-sym32
+@opindex msym32
+@opindex mno-sym32
+Assume (do not assume) that all symbols have 32-bit values, regardless
+of the selected ABI@. This option is useful in combination with
+@option{-mabi=64} and @option{-mno-abicalls} because it allows GCC
+to generate shorter and faster references to symbolic addresses.
+
@item -G @var{num}
@opindex G
@cindex smaller data references (MIPS)
@opindex msplit-addresses
@opindex mno-split-addresses
Enable (disable) use of the @code{%hi()} and @code{%lo()} assembler
-relocation operators. This option has been superceded by
+relocation operators. This option has been superseded by
@option{-mexplicit-relocs} but is retained for backwards compatibility.
@item -mexplicit-relocs
Other VR4120 errata require a nop to be inserted between certain pairs of
instructions. These errata are handled by the assembler, not by GCC itself.
+@item -mfix-vr4130
+@opindex mfix-vr4130
+Work around the VR4130 @code{mflo}/@code{mfhi} errata. The
+workarounds are implemented by the assembler rather than by GCC,
+although GCC will avoid using @code{mflo} and @code{mfhi} if the
+VR4130 @code{macc}, @code{macchi}, @code{dmacc} and @code{dmacchi}
+instructions are available instead.
+
@item -mfix-sb1
@itemx -mno-fix-sb1
@opindex mfix-sb1
@samp{601}, @samp{602}, @samp{603}, @samp{603e}, @samp{604},
@samp{604e}, @samp{620}, @samp{630}, @samp{740}, @samp{7400},
@samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
-@samp{860}, @samp{970}, @samp{common}, @samp{ec603e}, @samp{G3},
+@samp{860}, @samp{970}, @samp{8540}, @samp{common}, @samp{ec603e}, @samp{G3},
@samp{G4}, @samp{G5}, @samp{power}, @samp{power2}, @samp{power3},
@samp{power4}, @samp{power5}, @samp{powerpc}, @samp{powerpc64},
-@samp{rios}, @samp{rios1}, @samp{rios2}, @samp{rsc}, and @samp{rs64a}.
+@samp{rios}, @samp{rios1}, @samp{rios2}, @samp{rsc}, and @samp{rs64}.
@option{-mcpu=common} selects a completely generic processor. Code
generated under this option will run on any POWER or PowerPC processor.
@option{-mpowerpc}, while @option{-maix32} disables the 64-bit ABI and
implies @option{-mno-powerpc64}. GCC defaults to @option{-maix32}.
-@item -mxl-call
-@itemx -mno-xl-call
-@opindex mxl-call
-@opindex mno-xl-call
-On AIX, pass floating-point arguments to prototyped functions beyond the
-register save area (RSA) on the stack in addition to argument FPRs. The
-AIX calling convention was extended but not initially documented to
+@item -mxl-compat
+@itemx -mno-xl-compat
+@opindex mxl-compat
+@opindex mno-xl-compat
+Produce code that conforms more closely to IBM XLC semantics when using
+AIX-compatible ABI. Pass floating-point arguments to prototyped
+functions beyond the register save area (RSA) on the stack in addition
+to argument FPRs. Do not assume that most significant double in 128
+bit long double value is properly rounded when comparing values.
+
+The AIX calling convention was extended but not initially documented to
handle an obscure K&R C case of calling a function that takes the
address of its arguments with fewer arguments than declared. AIX XL
compilers access floating point arguments which do not fit in the
@itemx -malign-power
@opindex malign-natural
@opindex malign-power
-On AIX, Darwin, and 64-bit PowerPC GNU/Linux, the option
+On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option
@option{-malign-natural} overrides the ABI-defined alignment of larger
types, such as floating-point doubles, on their natural size-based boundary.
The option @option{-malign-power} instructs GCC to follow the ABI-specified
alignment rules. GCC defaults to the standard alignment defined in the ABI@.
+On 64-bit Darwin, natural alignment is the default, and @option{-malign-power}
+is not supported.
+
@item -msoft-float
@itemx -mhard-float
@opindex msoft-float
In general, code compiled with @option{-mbackchain} is call-compatible with
code compiled with @option{-mmo-backchain}; however, use of the backchain
for debugging purposes usually requires that the whole binary is built with
-@option{-mbackchain}. Note that the combination of @option{-mbackchain} and
-@option{-mpacked-stack} generates code that is not ABI-compatible.
+@option{-mbackchain}. Note that the combination of @option{-mbackchain},
+@option{-mpacked-stack} and @option{-mhard-float} is not supported. In order
+to build a linux kernel use @option{-msoft-float}.
The default is to not maintain the backchain.
the save area is always used to store the backchain, and the return address
register is always saved two words below the backchain.
-As long as the stack frame backchain is not used, code generated with
+As long as the stack frame backchain is not used, code generated with
@option{-mpacked-stack} is call-compatible with code generated with
@option{-mno-packed-stack}. Note that some non-FSF releases of GCC 2.95 for
S/390 or zSeries generated code that uses the stack frame backchain at run
time, not just for debugging purposes. Such code is not call-compatible
with code compiled with @option{-mpacked-stack}. Also, note that the
-combination of @option{-mbackchain} and @option{-mpacked-stack} generates code
-that is not ABI-compatible.
+combination of @option{-mbackchain},
+@option{-mpacked-stack} and @option{-mhard-float} is not supported. In order
+to build a linux kernel use @option{-msoft-float}.
The default is to not use the packed stack layout.
@opindex mapp-regs
Specify @option{-mapp-regs} to generate output using the global registers
2 through 4, which the SPARC SVR4 ABI reserves for applications. This
-is the default.
+is the default, except on Solaris.
To be fully SVR4 ABI compliant at the cost of some performance loss,
specify @option{-mno-app-regs}. You should compile libraries and system
@item -mlittle-endian
@opindex mlittle-endian
Generate code for a processor running in little-endian mode. It is only
-available for a few configurations and most notably not on Solaris.
+available for a few configurations and most notably not on Solaris and Linux.
@item -m32
@itemx -m64
@opindex fPIC
If supported for the target machine, emit position-independent code,
suitable for dynamic linking and avoiding any limit on the size of the
-global offset table. This option makes a difference on the m68k
-and the SPARC@.
+global offset table. This option makes a difference on the m68k,
+PowerPC and SPARC@.
Position-independent code requires special support, and therefore works
only on certain machines.
operator delete must always be of default visibility.
An overview of these techniques, their benefits and how to use them
-is at @w{@uref{http://www.nedprod.com/programs/gccvisibility.html}}.
+is at @w{@uref{http://gcc.gnu.org/wiki/Visibility}}.
@end table
Any macros defined before the precompiled header is included must
either be defined in the same way as when the precompiled header was
generated, or must not affect the precompiled header, which usually
-means that the they don't appear in the precompiled header at all.
+means that they don't appear in the precompiled header at all.
The @option{-D} option is one way to define a macro before a
precompiled header is included; using a @code{#define} can also do it.
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