@gccoptlist{
-ansi -std=@var{standard} -aux-info @var{filename} @gol
-fno-asm -fno-builtin -fno-builtin-@var{function} @gol
--fhosted -ffreestanding @gol
+-fhosted -ffreestanding -fms-extensions @gol
-trigraphs -traditional -traditional-cpp @gol
-fallow-single-precision -fcond-mismatch @gol
-fsigned-bitfields -fsigned-char @gol
-fno-optional-diags -fpermissive @gol
-frepo -fno-rtti -fstats -ftemplate-depth-@var{n} @gol
-fuse-cxa-atexit -fvtable-gc -fno-weak -nostdinc++ @gol
--fno-default-inline -Wctor-dtor-privacy @gol
+-fno-default-inline -Wabi -Wctor-dtor-privacy @gol
-Wnon-virtual-dtor -Wreorder @gol
-Weffc++ -Wno-deprecated @gol
-Wno-non-template-friend -Wold-style-cast @gol
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{
-fsyntax-only -pedantic -pedantic-errors @gol
--w -W -Wall -Waggregate-return @gol
+-w -W -Wall -Waggregate-return @gol
-Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment @gol
-Wconversion -Wno-deprecated-declarations @gol
-Wdisabled-optimization -Wno-div-by-zero -Werror @gol
-Wimplicit -Wimplicit-int @gol
-Wimplicit-function-declaration @gol
-Werror-implicit-function-declaration @gol
--Wimport -Winline @gol
+-Wimport -Winline -Wno-endif-labels @gol
-Wlarger-than-@var{len} -Wlong-long @gol
-Wmain -Wmissing-braces -Wmissing-declarations @gol
-Wmissing-format-attribute -Wmissing-noreturn @gol
-Wno-multichar -Wno-format-extra-args -Wno-format-y2k @gol
--Wno-import -Wpacked -Wpadded @gol
+-Wno-import -Wnonnull -Wpacked -Wpadded @gol
-Wparentheses -Wpointer-arith -Wredundant-decls @gol
-Wreturn-type -Wsequence-point -Wshadow @gol
--Wsign-compare -Wswitch -Wsystem-headers @gol
--Wtrigraphs -Wundef -Wuninitialized @gol
+-Wsign-compare -Wswitch -Wswitch-default -Wswitch-enum @gol
+-Wsystem-headers -Wtrigraphs -Wundef -Wuninitialized @gol
-Wunknown-pragmas -Wunreachable-code @gol
-Wunused -Wunused-function -Wunused-label -Wunused-parameter @gol
-Wunused-value -Wunused-variable -Wwrite-strings}
-fdelayed-branch -fdelete-null-pointer-checks @gol
-fexpensive-optimizations -ffast-math -ffloat-store @gol
-fforce-addr -fforce-mem -ffunction-sections @gol
--fgcse -fgcse-lm -fgcse-sm @gol
+-fgcse -fgcse-lm -fgcse-sm -floop-optimize -fcrossjumping @gol
+-fif-conversion -fif-conversion2 @gol
-finline-functions -finline-limit=@var{n} -fkeep-inline-functions @gol
-fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
--fmove-all-movables -fno-default-inline -fno-defer-pop @gol
+-fmove-all-movables -fnew-ra -fno-default-inline -fno-defer-pop @gol
-fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
--funsafe-math-optimizations -fno-trapping-math @gol
+-funsafe-math-optimizations -ffinite-math-only -fno-trapping-math @gol
-fno-zero-initialized-in-bss @gol
-fomit-frame-pointer -foptimize-register-move @gol
-foptimize-sibling-calls -fprefetch-loop-arrays @gol
-freduce-all-givs -fregmove -frename-registers @gol
+-freorder-blocks -freorder-functions @gol
-frerun-cse-after-loop -frerun-loop-opt @gol
--fschedule-insns -fschedule-insns2 @gol
+-fschedule-insns -fschedule-insns2 -fsignaling-nans @gol
-fsingle-precision-constant -fssa -fssa-ccp -fssa-dce @gol
--fstrength-reduce -fstrict-aliasing -fthread-jumps -ftrapv @gol
+-fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps -ftrapv @gol
-funroll-all-loops -funroll-loops @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
@c I wrote this xref this way to avoid overfull hbox. -- rms
@xref{Target Options}.
@gccoptlist{
--b @var{machine} -V @var{version}}
+-V @var{version} -b @var{machine}}
@item Machine Dependent Options
@xref{Submodel Options,,Hardware Models and Configurations}.
@emph{M68hc1x Options}
@gccoptlist{
-m6811 -m6812 -m68hc11 -m68hc12 @gol
--mauto-incdec -mshort -msoft-reg-count=@var{count}}
+-mauto-incdec -minmax -mlong-calls -mshort -msoft-reg-count=@var{count}}
@emph{VAX Options}
@gccoptlist{
-mcmodel=@var{code-model} @gol
-m32 -m64 @gol
-mapp-regs -mbroken-saverestore -mcypress @gol
--mepilogue -mfaster-structs -mflat @gol
+-mfaster-structs -mflat @gol
-mfpu -mhard-float -mhard-quad-float @gol
-mimpure-text -mlive-g0 -mno-app-regs @gol
--mno-epilogue -mno-faster-structs -mno-flat -mno-fpu @gol
+-mno-faster-structs -mno-flat -mno-fpu @gol
-mno-impure-text -mno-stack-bias -mno-unaligned-doubles @gol
-msoft-float -msoft-quad-float -msparclite -mstack-bias @gol
-msupersparc -munaligned-doubles -mv8}
-mcall-aix -mcall-sysv -mcall-netbsd @gol
-maix-struct-return -msvr4-struct-return
-mabi=altivec -mabi=no-altivec @gol
+-mabi=spe -mabi=no-spe @gol
+-misel=yes -misel=no @gol
-mprototype -mno-prototype @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
--msdata=@var{opt} -mvxworks -G @var{num} -pthread}
+-msdata=@var{opt} -mvxworks -mwindiss -G @var{num} -pthread}
@emph{RT Options}
@gccoptlist{
-m4650 -msingle-float -mmad @gol
-mstats -EL -EB -G @var{num} -nocpp @gol
-mabi=32 -mabi=n32 -mabi=64 -mabi=eabi @gol
--mfix7000 -mno-crt0 -mflush-func=@var{func} -mno-flush-func}
+-mfix7000 -mno-crt0 -mflush-func=@var{func} -mno-flush-func
+-mbranch-likely -mno-branch-likely}
@emph{i386 and x86-64 Options}
@gccoptlist{
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -momit-leaf-frame-pointer @gol
-mno-red-zone@gol
+-mcmodel=@var{code-model} @gol
-m32 -m64}
@emph{HPPA Options}
-mlong-calls -mno-long-calls -mep -mno-ep @gol
-mprolog-function -mno-prolog-function -mspace @gol
-mtda=@var{n} -msda=@var{n} -mzda=@var{n} @gol
+-mapp-regs -mno-app-regs @gol
+-mdisable-callt -mno-disable-callt @gol
+-mv850e @gol
-mv850 -mbig-switch}
@emph{NS32K Options}
-mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu @gol
-mabi=mmixware -mzero-extend -mknuthdiv -mtoplevel-symbols @gol
-melf -mbranch-predict -mno-branch-predict -mbase-addresses @gol
--mno-base-addresses}
+-mno-base-addresses -msingle-exit -mno-single-exit}
@emph{IA-64 Options}
@gccoptlist{
-fverbose-asm -fpack-struct -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
-fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fleading-underscore}
+-fargument-noalias-global -fleading-underscore -ftls-model=@var{model}}
@end table
@menu
@c @var{file}.p
@c @var{file}.pas
-@item @var{file}.ch
-@itemx @var{file}.chi
-CHILL source code (preprocessed with the traditional preprocessor).
-
@item @var{file}.s
Assembler code.
objective-c objc-cpp-output
assembler assembler-with-cpp
ada
-chill
f77 f77-cpp-input ratfor
java
+treelang
@end example
@item -x none
@cindex ISO support
@item -ansi
@opindex ansi
-In C mode, support all ISO C89 programs. In C++ mode,
+In C mode, support all ISO C90 programs. In C++ mode,
remove GNU extensions that conflict with ISO C++.
This turns off certain features of GCC that are incompatible with ISO
-C89 (when compiling C code), or of standard C++ (when compiling C++ code),
+C90 (when compiling C code), or of standard C++ (when compiling C++ code),
such as the @code{asm} and @code{typeof} keywords, and
predefined macros such as @code{unix} and @code{vax} that identify the
type of system you are using. It also enables the undesirable and
@item -std=
@opindex std
Determine the language standard. This option is currently only
-supported when compiling C@. A value for this option must be provided;
-possible values are
+supported when compiling C or C++. A value for this option must be
+provided; possible values are
@table @samp
@item c89
@itemx iso9899:1990
-ISO C89 (same as @option{-ansi}).
+ISO C90 (same as @option{-ansi}).
@item iso9899:199409
-ISO C89 as modified in amendment 1.
+ISO C90 as modified in amendment 1.
@item c99
@itemx c9x
names @samp{c9x} and @samp{iso9899:199x} are deprecated.
@item gnu89
-Default, ISO C89 plus GNU extensions (including some C99 features).
+Default, ISO C90 plus GNU extensions (including some C99 features).
@item gnu99
@item gnu9x
ISO C99 plus GNU extensions. When ISO C99 is fully implemented in GCC,
this will become the default. The name @samp{gnu9x} is deprecated.
+@item c++98
+The 1998 ISO C++ standard plus amendments.
+
+@item gnu++98
+The same as @option{-std=c++98} plus GNU extensions. This is the
+default for C++ code.
@end table
Even when this option is not specified, you can still use some of the
when @option{-std=c99} is not specified.
The @option{-std} options specifying some version of ISO C have the same
-effects as @option{-ansi}, except that features that were not in ISO C89
+effects as @option{-ansi}, except that features that were not in ISO C90
but are in the specified version (for example, @samp{//} comments and
the @code{inline} keyword in ISO C99) are not disabled.
@code{inline} is a standard keyword in ISO C99.
@item -fno-builtin
-@itemx -fno-builtin-@var{function} @r{(C and Objective-C only)}
+@itemx -fno-builtin-@var{function}
@opindex fno-builtin
@cindex built-in functions
Don't recognize built-in functions that do not begin with
cannot set a breakpoint on those calls, nor can you change the behavior
of the functions by linking with a different library.
-In C++, @option{-fno-builtin} is always in effect. The @option{-fbuiltin}
-option has no effect. Therefore, in C++, the only way to get the
-optimization benefits of built-in functions is to call the function
-using the @samp{__builtin_} prefix. The GNU C++ Standard Library uses
-built-in functions to implement many functions (like
-@code{std::strchr}), so that you automatically get efficient code.
-
-With the @option{-fno-builtin-@var{function}} option, not available
-when compiling C++, only the built-in function @var{function} is
+With the @option{-fno-builtin-@var{function}} option
+only the built-in function @var{function} is
disabled. @var{function} must not begin with @samp{__builtin_}. If a
function is named this is not built-in in this version of GCC, this
option is ignored. There is no corresponding
@xref{Standards,,Language Standards Supported by GCC}, for details of
freestanding and hosted environments.
+@item -fms-extensions
+@opindex fms-extensions
+Accept some non-standard constructs used in Microsoft header files.
+
@item -trigraphs
@opindex trigraphs
Support ISO C trigraphs. The @option{-ansi} option (and @option{-std}
functions will have linkage like inline functions; they just won't be
inlined by default.
+@item -Wabi @r{(C++ only)}
+@opindex Wabi
+Warn when G++ generates code that is probably not compatible with the
+vendor-neutral C++ ABI. Although an effort has been made to warn about
+all such cases, there are probably some cases that are not warned about,
+even though G++ is generating incompatible code. There may also be
+cases where warnings are emitted even though the code that is generated
+will be compatible.
+
+You should rewrite your code to avoid these warnings if you are
+concerned about the fact that code generated by G++ may not be binary
+compatible with code generated by other compilers.
+
+The known incompatibilites at this point include:
+
+@itemize @bullet
+
+@item
+Incorrect handling of tail-padding for bit-fields. G++ may attempt to
+pack data into the same byte as a base class. For example:
+
+@smallexample
+struct A @{ virtual void f(); int f1 : 1; @};
+struct B : public A @{ int f2 : 1; @};
+@end smallexample
+
+@noindent
+In this case, G++ will place @code{B::f2} into the same byte
+as@code{A::f1}; other compilers will not. You can avoid this problem
+by explicitly padding @code{A} so that its size is a multiple of the
+byte size on your platform; that will cause G++ and other compilers to
+layout @code{B} identically.
+
+@item
+Incorrect handling of tail-padding for virtual bases. G++ does not use
+tail padding when laying out virtual bases. For example:
+
+@smallexample
+struct A @{ virtual void f(); char c1; @};
+struct B @{ B(); char c2; @};
+struct C : public A, public virtual B @{@};
+@end smallexample
+
+@noindent
+In this case, G++ will not place @code{B} into the tail-padding for
+@code{A}; other compilers will. You can avoid this problem by
+explicitly padding @code{A} so that its size is a multiple of its
+alignment (ignoring virtual base classes); that will cause G++ and other
+compilers to layout @code{C} identically.
+
+@end itemize
+
@item -Wctor-dtor-privacy @r{(C++ only)}
@opindex Wctor-dtor-privacy
Warn when a class seems unusable, because all the constructors or
destructors in a class are private and the class has no friends or
-public static member functions.
+public static member functions. This warning is enabled by default.
@item -Wnon-virtual-dtor @r{(C++ only)}
@opindex Wnon-virtual-dtor
Warn when a class declares a non-virtual destructor that should probably
be virtual, because it looks like the class will be used polymorphically.
+This warning is enabled by @option{-Wall}.
@item -Wreorder @r{(C++ only)}
@opindex Wreorder
Here the compiler will warn that the member initializers for @samp{i}
and @samp{j} will be rearranged to match the declaration order of the
-members.
+members. This warning is enabled by @option{-Wall}.
@end table
The following @option{-W@dots{}} options are not affected by @option{-Wall}.
for example, @option{-Wno-implicit}. This manual lists only one of the
two forms, whichever is not the default.
-These options control the amount and kinds of warnings produced by GCC:
+The following options control the amount and kinds of warnings produced
+by GCC; for further, language-specific options also refer to
+@ref{C++ Dialect Options} and @ref{Objective-C Dialect Options}.
@table @gcctabopt
@cindex syntax checking
not in the C standard) families.
The formats are checked against the format features supported by GNU
-libc version 2.2. These include all ISO C89 and C99 features, as well
+libc version 2.2. These include all ISO C90 and C99 features, as well
as features from the Single Unix Specification and some BSD and GNU
extensions. Other library implementations may not support all these
features; GCC does not support warning about features that go beyond a
since those are not in any version of the C standard). @xref{C Dialect
Options,,Options Controlling C Dialect}.
+Since @option{-Wformat} also checks for null format arguments for
+several functions, @option{-Wformat} also implies @option{-Wnonnull}.
+
@option{-Wformat} is included in @option{-Wall}. For more control over some
aspects of format checking, the options @option{-Wno-format-y2k},
-@option{-Wno-format-extra-args}, @option{-Wformat-nonliteral},
-@option{-Wformat-security} and @option{-Wformat=2} are available, but are
-not included in @option{-Wall}.
+@option{-Wno-format-extra-args}, @option{-Wno-format-zero-length},
+@option{-Wformat-nonliteral}, @option{-Wformat-security}, and
+@option{-Wformat=2} are available, but are not included in @option{-Wall}.
@item -Wno-format-y2k
@opindex Wno-format-y2k
warning if the unused arguments are all pointers, since the Single
Unix Specification says that such unused arguments are allowed.
+@item -Wno-format-zero-length
+@opindex Wno-format-zero-length
+If @option{-Wformat} is specified, do not warn about zero-length formats.
+The C standard specifies that zero-length formats are allowed.
+
@item -Wformat-nonliteral
@opindex Wformat-nonliteral
If @option{-Wformat} is specified, also warn if the format string is not a
@option{-Wformat}. Currently equivalent to @samp{-Wformat
-Wformat-nonliteral -Wformat-security}.
+@item -Wnonnull
+@opindex Wnonnull
+Enable warning about passing a null pointer for arguments marked as
+requiring a non-null value by the @code{nonnull} function attribute.
+
+@option{-Wnonnull} is included in @option{-Wall} and @option{-Wformat}. It
+can be disabled with the @option{-Wno-nonnull} option.
+
@item -Wimplicit-int
@opindex Wimplicit-int
Warn when a declaration does not specify a type.
warning.) @code{case} labels outside the enumeration range also
provoke warnings when this option is used.
+@item -Wswitch-default
+@opindex Wswitch-switch
+Warn whenever a @code{switch} statement does not have a @code{default}
+case.
+
+@item -Wswitch-enum
+@opindex Wswitch-enum
+Warn whenever a @code{switch} statement has an index of enumeral type
+and lacks a @code{case} for one or more of the named codes of that
+enumeration. @code{case} labels outside the enumeration range also
+provoke warnings when this option is used.
+
@item -Wtrigraphs
@opindex Wtrigraphs
Warn if any trigraphs are encountered that might change the meaning of
@item -Wunused
@opindex Wunused
-All all the above @option{-Wunused} options combined.
+All the above @option{-Wunused} options combined.
In order to get a warning about an unused function parameter, you must
either specify @samp{-W -Wunused} or separately specify
you use that never return as @code{noreturn}. @xref{Function
Attributes}.
-@item -Wreorder @r{(C++ only)}
-@opindex Wreorder
-@cindex reordering, warning
-@cindex warning for reordering of member initializers
-Warn when the order of member initializers given in the code does not
-match the order in which they must be executed. For instance:
-
@item -Wunknown-pragmas
@opindex Wunknown-pragmas
@cindex warning for unknown pragmas
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.
+conjunction with macros. This also enables some language-specific
+warnings described in @ref{C++ Dialect Options} and
+@ref{Objective-C Dialect Options}.
@end table
The following @option{-W@dots{}} options are not implied by @option{-Wall}.
versa. The absence of these prototypes when compiling with traditional
C would cause serious problems. This is a subset of the possible
conversion warnings, for the full set use @option{-Wconversion}.
+
+@item
+Use of ISO C style function definitions. This warning intentionally is
+@emph{not} issued for prototype declarations or variadic functions
+because these ISO C features will appear in your code when using
+libiberty's traditional C compatibility macros, @code{PARAMS} and
+@code{VPARAMS}. This warning is also bypassed for nested functions
+because that feature is already a gcc extension and thus not relevant to
+traditional C compatibility.
@end itemize
@item -Wundef
@opindex Wundef
Warn if an undefined identifier is evaluated in an @samp{#if} directive.
+@item -Wendif-labels
+@opindex Wendif-labels
+Warn whenever an @samp{#else} or an @samp{#endif} are followed by text.
+
@item -Wshadow
@opindex Wshadow
Warn whenever a local variable shadows another local variable, parameter or
supported). This is the format used by SDB on most System V Release 4
systems.
+This option is deprecated.
+
@item -gdwarf+
@opindex gdwarf+
Produce debugging information in DWARF version 1 format (if that is
(GDB)@. The use of these extensions is likely to make other debuggers
crash or refuse to read the program.
+This option is deprecated.
+
@item -gdwarf-2
@opindex gdwarf-2
Produce debugging information in DWARF version 2 format (if that is
@itemx -gstabs@var{level}
@itemx -gcoff@var{level}
@itemx -gxcoff@var{level}
-@itemx -gdwarf@var{level}
-@itemx -gdwarf-2@var{level}
@itemx -gvms@var{level}
Request debugging information and also use @var{level} to specify how
much information. The default level is 2.
present in the program. Some debuggers support macro expansion when
you use @option{-g3}.
+Note that in order to avoid confusion between DWARF1 debug level 2,
+and DWARF2, neither @option{-gdwarf} nor @option{-gdwarf-2} accept
+a concatenated debug level. Instead use an additional @option{-g@var{level}}
+option to change the debug level for DWARF1 or DWARF2.
+
@cindex @code{prof}
@item -p
@opindex p
the source files you want data about, and you must also use it when
linking.
-@cindex @code{tcov}
-@item -a
-@opindex a
-Generate extra code to write profile information for basic blocks, which will
-record the number of times each basic block is executed, the basic block start
-address, and the function name containing the basic block. If @option{-g} is
-used, the line number and filename of the start of the basic block will also be
-recorded. If not overridden by the machine description, the default action is
-to append to the text file @file{bb.out}.
-
-This data could be analyzed by a program like @code{tcov}. Note,
-however, that the format of the data is not what @code{tcov} expects.
-Eventually GNU @code{gprof} should be extended to process this data.
-
@item -Q
@opindex Q
Makes the compiler print out each function name as it is compiled, and
@item -fprofile-arcs
@opindex fprofile-arcs
-Instrument @dfn{arcs} during compilation to generate coverage data
-or for profile-directed block ordering. During execution the program
+Instrument @dfn{arcs} during compilation to generate coverage data or
+for profile-directed block ordering. During execution the program
records how many times each branch is executed and how many times it is
taken. When the compiled program exits it saves this data to a file
-called @file{@var{sourcename}.da} for each source file.
+called @file{@var{auxname}.da} for each source file. @var{auxname} is
+generated from the name of the output file, if explicitly specified and
+it is not the final executable, otherwise it is the basename of the
+source file. In both cases any suffix is removed (e.g. @file{foo.da}
+for input file @file{dir/foo.c}, or @file{dir/foo.da} for output file
+specified as @option{-o dir/foo.o}).
For profile-directed block ordering, compile the program with
@option{-fprofile-arcs} plus optimization and code generation options,
Control Optimization}).
The other use of @option{-fprofile-arcs} is for use with @code{gcov},
-when it is used with the @option{-ftest-coverage} option. GCC
-supports two methods of determining code coverage: the options that
-support @code{gcov}, and options @option{-a} and @option{-ax}, which
-write information to text files. The options that support @code{gcov}
-do not need to instrument every arc in the program, so a program compiled
-with them runs faster than a program compiled with @option{-a}, which
-adds instrumentation code to every basic block in the program. The
-tradeoff: since @code{gcov} does not have execution counts for all
-branches, it must start with the execution counts for the instrumented
-branches, and then iterate over the program flow graph until the entire
-graph has been solved. Hence, @code{gcov} runs a little more slowly than
-a program which uses information from @option{-a} and @option{-ax}.
+when it is used with the @option{-ftest-coverage} option.
With @option{-fprofile-arcs}, for each function of your program GCC
creates a program flow graph, then finds a spanning tree for the graph.
instrumentation code can be added to the block; otherwise, a new basic
block must be created to hold the instrumentation code.
-This option makes it possible to estimate branch probabilities and to
-calculate basic block execution counts. In general, basic block
-execution counts as provided by @option{-a} do not give enough
-information to estimate all branch probabilities.
-
@need 2000
@item -ftest-coverage
@opindex ftest-coverage
Create data files for the @code{gcov} code-coverage utility
-(@pxref{Gcov,, @code{gcov}: a GCC Test Coverage Program}).
-The data file names begin with the name of your source file:
+(@pxref{Gcov,, @code{gcov}: a GCC Test Coverage Program}). See
+@option{-fprofile-arcs} option above for a description of @var{auxname}.
@table @gcctabopt
-@item @var{sourcename}.bb
+@item @var{auxname}.bb
A mapping from basic blocks to line numbers, which @code{gcov} uses to
associate basic block execution counts with line numbers.
-@item @var{sourcename}.bbg
+@item @var{auxname}.bbg
A list of all arcs in the program flow graph. This allows @code{gcov}
to reconstruct the program flow graph, so that it can compute all basic
block and arc execution counts from the information in the
-@code{@var{sourcename}.da} file.
+@file{@var{auxname}.da} file.
@end table
Use @option{-ftest-coverage} with @option{-fprofile-arcs}; the latter
execution counts to another data file:
@table @gcctabopt
-@item @var{sourcename}.da
+@item @var{auxname}.da
Runtime arc execution counts, used in conjunction with the arc
-information in the file @code{@var{sourcename}.bbg}.
+information in the file @file{@var{auxname}.bbg}.
@end table
Coverage data will map better to the source files if
Says to make debugging dumps during compilation at times specified by
@var{letters}. This is used for debugging the compiler. The file names
for most of the dumps are made by appending a pass number and a word to
-the source file name (e.g. @file{foo.c.00.rtl} or @file{foo.c.01.sibling}).
-Here are the possible letters for use in @var{letters}, and their meanings:
+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. In both cases any
+suffix is removed (e.g. @file{foo.00.rtl} or @file{foo.01.sibling}).
+Here are the possible letters for use in @var{letters}, and their
+meanings:
@table @samp
@item A
As compared to @option{-O}, this option increases both compilation time
and the performance of the generated code.
-@option{-O2} turns on all optional optimizations except for loop unrolling,
-function inlining, and register renaming. It also turns on the
-@option{-fforce-mem} option on all machines and frame pointer elimination
-on machines where doing so does not interfere with debugging.
+@option{-O2} turns on all optional optimizations except for loop
+unrolling, function inlining, and register renaming. It also turns on
+the @option{-fforce-mem} and @option{-fstrict-aliasing} option on all
+machines and frame pointer elimination on machines where doing so does
+not interfere with debugging.
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
have distinct location, so using this option will result in non-conforming
behavior.
+@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 -fno-function-cse
@opindex fno-function-cse
Do not put function addresses in registers; make each instruction that
@item -ffast-math
@opindex ffast-math
-Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, and @*
-@option{-fno-trapping-math}.
+Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @*
+@option{-fno-trapping-math}, @option{-ffinite-math-only} and @*
+@option{-fno-signaling-nans}.
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
The default is @option{-fno-unsafe-math-optimizations}.
+@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
+it can result in incorrect output for programs which depend on
+an exact implementation of IEEE or ISO rules/specifications.
+
+The default is @option{-fno-finite-math-only}.
+
@item -fno-trapping-math
@opindex fno-trapping-math
Compile code assuming that floating-point operations cannot generate
-user-visible traps. Setting this option may allow faster code
-if one relies on ``non-stop'' IEEE arithmetic, for example.
+user-visible traps. These traps include division by zero, overflow,
+underflow, inexact result and invalid operation. This option implies
+@option{-fno-signaling-nans}. Setting this option may allow faster
+code if one relies on ``non-stop'' IEEE arithmetic, for example.
This option should never be turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
The default is @option{-ftrapping-math}.
+@item -fsignaling-nans
+@opindex fsignaling-nans
+Compile code assuming that IEEE signaling NaNs may generate user-visible
+traps during floating-point operations. Setting this option disables
+optimizations that may change the number of exceptions visible with
+signaling NaNs. This option implies @option{-ftrapping-math}.
+
+This option causes the preprocessor macro @code{__SUPPORT_SNAN__} to
+be defined.
+
+The default is @option{-fno-signaling-nans}.
+
+This option is experimental and does not currently guarantee to
+disable all GCC optimizations that affect signaling NaN behavior.
+
@item -fno-zero-initialized-in-bss
@opindex fno-zero-initialized-in-bss
If the target supports a BSS section, GCC by default puts variables that
When used in conjunction with @option{-fgcse-lm}, loops containing a load/store sequence
can be changed to a load before the loop and a store after the loop.
+@item -floop-optimize
+@opindex floop-optimize
+Perform loop optimizations: move constant expressions out of loops, simplify
+exit test conditions and optionally do strength-reduction and loop unrolling as
+well.
+
+@item -fcrossjumping
+@opindex crossjumping
+Perform cross-jumping transformation. This transformation unifies equivalent code and save code size. The
+resulting code may or may not perform better than without cross-jumping.
+
+@item -fif-conversion
+@opindex if-conversion
+Attempt to transform conditional jumps into branch-less equivalents. This
+include use of conditional moves, min, max, set flags and abs instructions, and
+some tricks doable by standard arithmetics. The use of conditional execution
+on chips where it is available is controlled by @code{if-conversion2}.
+
+@item -fif-conversion2
+@opindex if-conversion2
+Use conditional execution (where available) to transform conditional jumps into
+branch-less equivalents.
+
@item -fdelete-null-pointer-checks
@opindex fdelete-null-pointer-checks
Use global dataflow analysis to identify and eliminate useless checks
For all machines, optimization level 2 and higher enables this flag by
default.
+@item -ftracer
+@opindex ftracer
+Perform tail duplication to enlarge superblock size. This transformation
+simplifies the control flow of the function allowing other optimizations to do
+better job.
+
@item -funroll-loops
@opindex funroll-loops
Unroll loops whose number of iterations can be determined at compile
reduce non-determinism, possibly at the expense of inferior
optimization.
+@item -freorder-blocks
+@opindex freorder-blocks
+Reorder basic blocks in the compiled function in order to reduce number of
+taken branches and improve code locality.
+
+@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
+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
+place them in resonable way.
+
+Also profile feedback must be available in to make this option effective. See
+@option{-fprofile-arcs} for details.
+
@item -fstrict-aliasing
@opindex fstrict-aliasing
Allows the compiler to assume the strictest aliasing rules applicable to
allowed to alias. For an example, see the C front-end function
@code{c_get_alias_set}.
+For all machines, optimization level 2 and higher enables this flag by
+default.
+
@item -falign-functions
@itemx -falign-functions=@var{n}
@opindex falign-functions
will not be inlined. This option is precisely equivalent to
@option{-finline-limit}.
-@end table
-@end table
-
-@node Preprocessor Options
-@section Options Controlling the Preprocessor
-@cindex preprocessor options
-@cindex options, preprocessor
-
-These options control the C preprocessor, which is run on each C source
-file before actual compilation.
+@item max-unrolled-insns
+The maximum number of instructions that a loop should have if that loop
+is unrolled, and if the loop is unrolled, it determines how many times
+the loop code is unrolled.
-If you use the @option{-E} option, nothing is done except preprocessing.
-Some of these options make sense only together with @option{-E} because
-they cause the preprocessor output to be unsuitable for actual
-compilation.
+@item hot-bb-count-fraction
+Select fraction of the maximal count of repetitions of basic block in program
+given basic block needs to have to be considered hot.
-@table @gcctabopt
-@item -include @var{file}
-@opindex include
-Process @var{file} as input before processing the regular input file.
-In effect, the contents of @var{file} are compiled first. Any @option{-D}
-and @option{-U} options on the command line are always processed before
-@option{-include @var{file}}, regardless of the order in which they are
-written. All the @option{-include} and @option{-imacros} options are
-processed in the order in which they are written.
-
-@item -imacros @var{file}
-@opindex imacros
-Process @var{file} as input, discarding the resulting output, before
-processing the regular input file. Because the output generated from
-@var{file} is discarded, the only effect of @option{-imacros @var{file}}
-is to make the macros defined in @var{file} available for use in the
-main input. All the @option{-include} and @option{-imacros} options are
-processed in the order in which they are written.
-
-@item -idirafter @var{dir}
-@opindex idirafter
-@cindex second include path
-Add the directory @var{dir} to the second include path. The directories
-on the second include path are searched when a header file is not found
-in any of the directories in the main include path (the one that
-@option{-I} adds to).
-
-@item -iprefix @var{prefix}
-@opindex iprefix
-Specify @var{prefix} as the prefix for subsequent @option{-iwithprefix}
-options.
-
-@item -iwithprefix @var{dir}
-@opindex iwithprefix
-Add a directory to the second include path. The directory's name is
-made by concatenating @var{prefix} and @var{dir}, where @var{prefix} was
-specified previously with @option{-iprefix}. If you have not specified a
-prefix yet, the directory containing the installed passes of the
-compiler is used as the default.
-
-@item -iwithprefixbefore @var{dir}
-@opindex iwithprefixbefore
-Add a directory to the main include path. The directory's name is made
-by concatenating @var{prefix} and @var{dir}, as in the case of
-@option{-iwithprefix}.
-
-@item -isystem @var{dir}
-@opindex isystem
-Add a directory to the beginning of the second include path, marking it
-as a system directory, so that it gets the same special treatment as
-is applied to the standard system directories.
-
-@item -nostdinc
-@opindex nostdinc
-Do not search the standard system directories for header files. Only
-the directories you have specified with @option{-I} options (and the
-current directory, if appropriate) are searched. @xref{Directory
-Options}, for information on @option{-I}.
-
-By using both @option{-nostdinc} and @option{-I-}, you can limit the include-file
-search path to only those directories you specify explicitly.
-
-@item -remap
-@opindex remap
-When searching for a header file in a directory, remap file names if a
-file named @file{header.gcc} exists in that directory. This can be used
-to work around limitations of file systems with file name restrictions.
-The @file{header.gcc} file should contain a series of lines with two
-tokens on each line: the first token is the name to map, and the second
-token is the actual name to use.
-
-@item -undef
-@opindex undef
-Do not predefine any nonstandard macros. (Including architecture flags).
+@item hot-bb-frequency-fraction
+Select fraction of the maximal frequency of executions of basic block in
+function given basic block needs to have to be considered hot
-@item -E
-@opindex E
-Run only the C preprocessor. Preprocess all the C source files
-specified and output the results to standard output or to the
-specified output file.
+@item tracer-dynamic-coverage
+@itemx tracer-dynamic-coverage-feedback
-@item -C
-@opindex C
-Tell the preprocessor not to discard comments. Used with the
-@option{-E} option.
-
-@item -P
-@opindex P
-Tell the preprocessor not to generate @samp{#line} directives.
-Used with the @option{-E} option.
-
-@cindex make
-@cindex dependencies, make
-@item -M
-@opindex M
-Instead of outputting the result of preprocessing, output a rule
-suitable for @command{make} describing the dependencies of the main
-source file. The preprocessor outputs one @command{make} rule containing
-the object file name for that source file, a colon, and the names of all
-the included files, including those coming from @option{-include} or
-@option{-imacros} command line options.
-
-Unless specified explicitly (with @option{-MT} or @option{-MQ}), the
-object file name consists of the basename of the source file with any
-suffix replaced with object file suffix. If there are many included
-files then the rule is split into several lines using @samp{\}-newline.
-The rule has no commands.
-
-Passing @option{-M} to the driver implies @option{-E}.
-
-@item -MM
-@opindex MM
-Like @option{-M} but do not mention header files that are found in
-system header directories, nor header files that are included,
-directly or indirectly, from such a header.
-
-This implies that the choice of angle brackets or double quotes in an
-@samp{#include} directive does not in itself determine whether that
-header will appear in @option{-MM} dependency output. This is a
-slight change in semantics from GCC versions 3.0 and earlier.
-
-@item -MD
-@opindex MD
-@option{-MD} is equivalent to @option{-M -MF @var{file}}, except that
-@option{-E} is not implied. The driver determines @var{file} based on
-whether an @option{-o} option is given. If it is, the driver uses its
-argument but with a suffix of @file{.d}, otherwise it take the
-basename of the input file and applies a @file{.d} suffix.
-
-If @option{-MD} is used in conjunction with @option{-E}, any
-@option{-o} switch is understood to specify the dependency output file
-(but @pxref{-MF}), but if used without @option{-E}, each @option{-o}
-is understood to specify a target object file.
-
-Since @option{-E} is not implied, @option{-MD} can be used to generate
-a dependency output file as a side-effect of the compilation process.
-
-With Mach, you can use the utility @code{md} to merge multiple
-dependency files into a single dependency file suitable for using with
-the @samp{make} command.
-
-@item -MMD
-@opindex MMD
-Like @option{-MD} except mention only user header files, not system
--header files.
-
-@item -MF @var{file}
-@opindex MF
-@anchor{-MF}
-When used with @option{-M} or @option{-MM}, specifies a
-file to write the dependencies to. If no @option{-MF} switch is given
-the preprocessor sends the rules to the same place it would have sent
-preprocessed output.
-
-When used with the driver options @option{-MD} or @option{-MMD},
-@option{-MF} overrides the default dependency output file.
-
-Another way to specify output of a @code{make} rule is by setting
-the environment variable @env{DEPENDENCIES_OUTPUT} (@pxref{Environment
-Variables}).
-
-@item -MG
-@opindex MG
-When used with @option{-M} or @option{-MM}, @option{-MG} says to treat missing
-header files as generated files and assume they live in the same
-directory as the source file. It suppresses preprocessed output, as a
-missing header file is ordinarily an error.
-
-This feature is used in automatic updating of makefiles.
-
-@item -MP
-@opindex MP
-This option instructs CPP to add a phony target for each dependency
-other than the main file, causing each to depend on nothing. These
-dummy rules work around errors @code{make} gives if you remove header
-files without updating the @code{Makefile} to match.
-
-This is typical output:-
+This value is used to limit superblock formation once given percentage of
+executed instructions is covered. This limits unnecesary code size expansion.
-@smallexample
-/tmp/test.o: /tmp/test.c /tmp/test.h
+The @option{tracer-dynamic-coverage-feedback} is used only when profile
+feedback is available. The real profiles (as opposed to statically estimated
+ones) are much less balanced allowing the threshold to be larger value.
-/tmp/test.h:
-@end smallexample
+@item tracer-max-code-growth
+Stop tail duplication once code growth has reached given percentage. This is
+rather hokey argument, as most of the duplicates will be elliminated later in
+cross jumping, so it may be set to much higher values than is the desired code
+growth.
-@item -MQ @var{target}
-@item -MT @var{target}
-@opindex MQ
-@opindex MT
-By default CPP uses the main file name, including any path, and appends
-the object suffix, normally ``.o'', to it to obtain the name of the
-target for dependency generation. With @option{-MT} you can specify a
-target yourself, overriding the default one.
+@item tracer-min-branch-ratio
-If you want multiple targets, you can specify them as a single argument
-to @option{-MT}, or use multiple @option{-MT} options.
+Stop reverse growth when the reverse probability of best edge is less than this
+threshold (in percent).
-The targets you specify are output in the order they appear on the
-command line. @option{-MQ} is identical to @option{-MT}, except that the
-target name is quoted for Make, but with @option{-MT} it isn't. For
-example, @option{-MT '$(objpfx)foo.o'} gives
+@item tracer-min-branch-ratio
+@itemx tracer-min-branch-ratio-feedback
-@smallexample
-$(objpfx)foo.o: /tmp/foo.c
-@end smallexample
+Stop forward growth if the best edge do have probability lower than this
+threshold.
-but @option{-MQ '$(objpfx)foo.o'} gives
+Similary to @option{tracer-dynamic-coverage} two values are present, one for
+compilation for profile feedback and one for compilation without. The value
+for compilation with profile feedback needs to be more conservative (higher) in
+order to make tracer effective.
-@smallexample
-$$(objpfx)foo.o: /tmp/foo.c
-@end smallexample
-
-The default target is automatically quoted, as if it were given with
-@option{-MQ}.
-
-@item -H
-@opindex H
-Print the name of each header file used, in addition to other normal
-activities.
-
-@item -A@var{question}(@var{answer})
-@opindex A
-Assert the answer @var{answer} for @var{question}, in case it is tested
-with a preprocessing conditional such as @samp{#if
-#@var{question}(@var{answer})}. @option{-A-} disables the standard
-assertions that normally describe the target machine.
-
-@item -D@var{macro}
-@opindex D
-Define macro @var{macro} with the string @samp{1} as its definition.
-
-@item -D@var{macro}=@var{defn}
-Define macro @var{macro} as @var{defn}. All instances of @option{-D} on
-the command line are processed before any @option{-U} options.
-
-Any @option{-D} and @option{-U} options on the command line are processed in
-order, and always before @option{-imacros @var{file}}, regardless of the
-order in which they are written.
-
-@item -U@var{macro}
-@opindex U
-Undefine macro @var{macro}. @option{-U} options are evaluated after all
-@option{-D} options, but before any @option{-include} and @option{-imacros}
-options.
-
-Any @option{-D} and @option{-U} options on the command line are processed in
-order, and always before @option{-imacros @var{file}}, regardless of the
-order in which they are written.
-
-@item -dM
-@opindex dM
-Tell the preprocessor to output only a list of the macro definitions
-that are in effect at the end of preprocessing. Used with the @option{-E}
-option.
-
-@item -dD
-@opindex dD
-Tell the preprocessing to pass all macro definitions into the output, in
-their proper sequence in the rest of the output.
-
-@item -dN
-@opindex dN
-Like @option{-dD} except that the macro arguments and contents are omitted.
-Only @samp{#define @var{name}} is included in the output.
-
-@item -dI
-@opindex dI
-Output @samp{#include} directives in addition to the result of
-preprocessing.
-
-@item -fpreprocessed
-@opindex fpreprocessed
-Indicate to the preprocessor that the input file has already been
-preprocessed. This suppresses things like macro expansion, trigraph
-conversion, escaped newline splicing, and processing of most directives.
-The preprocessor still recognizes and removes comments, so that you can
-pass a file preprocessed with @option{-C} to the compiler without
-problems. In this mode the integrated preprocessor is little more than
-a tokenizer for the front ends.
-
-@option{-fpreprocessed} is implicit if the input file has one of the
-extensions @samp{i}, @samp{ii} or @samp{mi}. These are the extensions
-that GCC uses for preprocessed files created by @option{-save-temps}.
-
-@item -trigraphs
-@opindex trigraphs
-Process ISO standard trigraph sequences. These are three-character
-sequences, all starting with @samp{??}, that are defined by ISO C to
-stand for single characters. For example, @samp{??/} stands for
-@samp{\}, so @samp{'??/n'} is a character constant for a newline. By
-default, GCC ignores trigraphs, but in standard-conforming modes it
-converts them. See the @option{-std} and @option{-ansi} options.
-
-The nine trigraph sequences are
-@table @samp
-@item ??(
-@expansion{} @samp{[}
-
-@item ??)
-@expansion{} @samp{]}
-
-@item ??<
-@expansion{} @samp{@{}
-
-@item ??>
-@expansion{} @samp{@}}
-
-@item ??=
-@expansion{} @samp{#}
-
-@item ??/
-@expansion{} @samp{\}
-
-@item ??'
-@expansion{} @samp{^}
-
-@item ??!
-@expansion{} @samp{|}
+@end table
+@end table
-@item ??-
-@expansion{} @samp{~}
+@node Preprocessor Options
+@section Options Controlling the Preprocessor
+@cindex preprocessor options
+@cindex options, preprocessor
-@end table
+These options control the C preprocessor, which is run on each C source
+file before actual compilation.
-Trigraph support is not popular, so many compilers do not implement it
-properly. Portable code should not rely on trigraphs being either
-converted or ignored.
+If you use the @option{-E} option, nothing is done except preprocessing.
+Some of these options make sense only together with @option{-E} because
+they cause the preprocessor output to be unsuitable for actual
+compilation.
-@item -Wp,@var{option}
@opindex Wp
-Pass @var{option} as an option to the preprocessor. If @var{option}
-contains commas, it is split into multiple options at the commas.
-@end table
+You can use @option{-Wp,@var{option}} to bypass the compiler driver
+and pass @var{option} directly through to the preprocessor. If
+@var{option} contains commas, it is split into multiple options at the
+commas. However, many options are modified, translated or interpreted
+by the compiler driver before being passed to the preprocessor, and
+@option{-Wp} forcibly bypasses this phase. The preprocessor's direct
+interface is undocumented and subject to change, so whenever possible
+you should avoid using @option{-Wp} and let the driver handle the
+options instead.
+
+@include cppopts.texi
@node Assembler Options
@section Passing Options to the Assembler
order; the standard system directories come after.
If a standard system include directory, or a directory specified with
-@option{-isystem}, is also specified with @option{-I}, it will be
-searched only in the position requested by @option{-I}. Also, it will
-not be considered a system include directory. If that directory really
-does contain system headers, there is a good chance that they will
-break. For instance, if GCC's installation procedure edited the headers
-in @file{/usr/include} to fix bugs, @samp{-I/usr/include} will cause the
-original, buggy headers to be found instead of the corrected ones. GCC
-will issue a warning when a system include directory is hidden in this
-way.
+@option{-isystem}, is also specified with @option{-I}, the @option{-I}
+option will be ignored. The directory will still be searched but as a
+system directory at its normal position in the system include chain.
+This is to ensure that GCC's procedure to fix buggy system headers and
+the ordering for the include_next directive are not inadvertantly changed.
+If you really need to change the search order for system directories,
+use the @option{-nostdinc} and/or @option{-isystem} options.
@item -I-
@opindex I-
@cindex compiler version, specifying
@cindex target machine, specifying
-By default, GCC compiles code for the same type of machine that you
-are using. However, it can also be installed as a cross-compiler, to
-compile for some other type of machine. In fact, several different
-configurations of GCC, for different target machines, can be
-installed side by side. Then you specify which one to use with the
-@option{-b} option.
-
-In addition, older and newer versions of GCC can be installed side
-by side. One of them (probably the newest) will be the default, but
-you may sometimes wish to use another.
+The usual way to run GCC is to run the executable called @file{gcc}, or
+@file{<machine>-gcc} when cross-compiling, or
+@file{<machine>-gcc-<version>} to run a version other than the one that
+was installed last. Sometimes this is inconvenient, so GCC provides
+options that will switch to another cross-compiler or version.
@table @gcctabopt
@item -b @var{machine}
@opindex b
The argument @var{machine} specifies the target machine for compilation.
-This is useful when you have installed GCC as a cross-compiler.
The value to use for @var{machine} is the same as was specified as the
machine type when configuring GCC as a cross-compiler. For
i386v}, meaning to compile for an 80386 running System V, then you
would specify @option{-b i386v} to run that cross compiler.
-When you do not specify @option{-b}, it normally means to compile for
-the same type of machine that you are using.
-
@item -V @var{version}
@opindex V
The argument @var{version} specifies which version of GCC to run.
This is useful when multiple versions are installed. For example,
@var{version} might be @samp{2.0}, meaning to run GCC version 2.0.
-
-The default version, when you do not specify @option{-V}, is the last
-version of GCC that you installed.
@end table
-The @option{-b} and @option{-V} options actually work by controlling part of
-the file name used for the executable files and libraries used for
-compilation. A given version of GCC, for a given target machine, is
-normally kept in the directory @file{/usr/local/lib/gcc-lib/@var{machine}/@var{version}}.
-
-Thus, sites can customize the effect of @option{-b} or @option{-V} either by
-changing the names of these directories or adding alternate names (or
-symbolic links). If in directory @file{/usr/local/lib/gcc-lib/} the
-file @file{80386} is a link to the file @file{i386v}, then @option{-b
-80386} becomes an alias for @option{-b i386v}.
-
-In one respect, the @option{-b} or @option{-V} do not completely change
-to a different compiler: the top-level driver program @command{gcc}
-that you originally invoked continues to run and invoke the other
-executables (preprocessor, compiler per se, assembler and linker)
-that do the real work. However, since no real work is done in the
-driver program, it usually does not matter that the driver program
-in use is not the one for the specified target. It is common for the
-interface to the other executables to change incompatibly between
-compiler versions, so unless the version specified is very close to that
-of the driver (for example, @option{-V 3.0} with a driver program from GCC
-version 3.0.1), use of @option{-V} may not work; for example, using
-@option{-V 2.95.2} will not work with a driver program from GCC 3.0.
-
-The only way that the driver program depends on the target machine is
-in the parsing and handling of special machine-specific options.
-However, this is controlled by a file which is found, along with the
-other executables, in the directory for the specified version and
-target machine. As a result, a single installed driver program adapts
-to any specified target machine, and sufficiently similar compiler
-versions.
-
-The driver program executable does control one significant thing,
-however: the default version and target machine. Therefore, you can
-install different instances of the driver program, compiled for
-different targets or versions, under different names.
-
-For example, if the driver for version 2.0 is installed as @command{ogcc}
-and that for version 2.1 is installed as @command{gcc}, then the command
-@command{gcc} will use version 2.1 by default, while @command{ogcc} will use
-2.0 by default. However, you can choose either version with either
-command with the @option{-V} option.
+The @option{-V} and @option{-b} options work by running the
+@file{<machine>-gcc-<version>} executable, so there's no real reason to
+use them if you can just run that directly.
@node Submodel Options
@section Hardware Models and Configurations
Enable the use of 68HC12 pre and post auto-increment and auto-decrement
addressing modes.
+@item -minmax
+@itemx -nominmax
+@opindex minmax
+@opindex mnominmax
+Enable the use of 68HC12 min and max instructions.
+
+@item -mlong-calls
+@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
+Treat all calls as being far away (near). If calls are assumed to be
+far away, the compiler will use the @code{call} instruction to
+call a function and the @code{rtc} instruction for returning.
+
@item -mshort
@opindex mshort
Consider type @code{int} to be 16 bits wide, like @code{short int}.
this is much slower than calling the ABI library routines. Thus the
@option{-msoft-quad-float} option is the default.
-@item -mno-epilogue
-@itemx -mepilogue
-@opindex mno-epilogue
-@opindex mepilogue
-With @option{-mepilogue} (the default), the compiler always emits code for
-function exit at the end of each function. Any function exit in
-the middle of the function (such as a return statement in C) will
-generate a jump to the exit code at the end of the function.
-
-With @option{-mno-epilogue}, the compiler tries to emit exit code inline
-at every function exit.
-
@item -mno-flat
@itemx -mflat
@opindex mno-flat
@option{-mabi=altivec} to adjust the current ABI with AltiVec ABI
enhancements.
+@item -mabi=spe
+@opindex mabi=spe
+Extend the current ABI with SPE ABI extensions. This does not change
+the default ABI, instead it adds the SPE ABI extensions to the current
+ABI@.
+
+@item -mabi=no-spe
+@opindex mabi=no-spe
+Disable Booke SPE ABI extensions for the current ABI.
+
+@item -misel=@var{yes/no}
+@itemx -misel
+@opindex misel
+This switch enables or disables the generation of ISEL instructions.
+
@item -mfull-toc
@itemx -mno-fp-in-toc
@itemx -mno-sum-in-toc
On System V.4 and embedded PowerPC systems, specify that you are
compiling for a VxWorks system.
+@item -mwindiss
+@opindex mwindiss
+Specify that you are compiling for the WindISS simulation environment.
+
@item -memb
@opindex memb
On embedded PowerPC systems, set the @var{PPC_EMB} bit in the ELF flags
On System V.4 and embedded PowerPC systems do (do not) emit register
names in the assembly language output using symbolic forms.
+@item -mlongcall
+@itemx -mno-longcall
+@opindex mlongcall
+@opindex mno-longcall
+Default to making all function calls via pointers, so that functions
+which reside further than 64 megabytes (67,108,864 bytes) from the
+current location can be called. This setting can be overridden by the
+@code{shortcall} function attribute, or by @code{#pragma longcall(0)}.
+
+Some linkers are capable of detecting out-of-range calls and generating
+glue code on the fly. On these systems, long calls are unnecessary and
+generate slower code. As of this writing, the AIX linker can do this,
+as can the GNU linker for PowerPC/64. It is planned to add this feature
+to the GNU linker for 32-bit PowerPC systems as well.
+
+In the future, we may cause GCC to ignore all longcall specifications
+when the linker is known to generate glue.
+
@item -pthread
@opindex pthread
Adds support for multithreading with the @dfn{pthreads} library.
results in smaller code, but slower execution, since scratch space must
be allocated dynamically.
-@cindex @file{varargs.h} and RT PC
@cindex @file{stdarg.h} and RT PC
@item -mfp-arg-in-fpregs
@opindex mfp-arg-in-fpregs
Use a calling sequence incompatible with the IBM calling convention in
which floating point arguments are passed in floating point registers.
-Note that @code{varargs.h} and @code{stdarg.h} will not work with
-floating point operands if this option is specified.
+Note that @code{stdarg.h} will not work with floating point operands
+if this option is specified.
@item -mfp-arg-in-gregs
@opindex mfp-arg-in-gregs
@table @gcctabopt
-@item -march=@var{cpu-type}
+@item -march=@var{arch}
@opindex march
-Assume the defaults for the machine type @var{cpu-type} when generating
-instructions. The choices for @var{cpu-type} are @samp{r2000}, @samp{r3000},
-@samp{r3900}, @samp{r4000}, @samp{r4100}, @samp{r4300}, @samp{r4400},
-@samp{r4600}, @samp{r4650}, @samp{r5000}, @samp{r6000}, @samp{r8000},
-and @samp{orion}. Additionally, the @samp{r2000}, @samp{r3000},
-@samp{r4000}, @samp{r5000}, and @samp{r6000} can be abbreviated as
-@samp{r2k} (or @samp{r2K}), @samp{r3k}, etc.
-
-@item -mtune=@var{cpu-type}
+Generate code that will run on @var{arch}, which can be the name of a
+generic MIPS ISA, or the name of a particular processor. The ISA names
+are: @samp{mips1}, @samp{mips2}, @samp{mips3}, @samp{mips4}, @samp{mips32}
+and @samp{mips64}. The processor names are: @samp{r2000},
+@samp{r3000}, @samp{r3900}, @samp{r4000}, @samp{vr4100}, @samp{vr4300},
+@samp{r4400}, @samp{r4600}, @samp{r4650}, @samp{vr5000}, @samp{r6000},
+@samp{r8000}, @samp{4kc}, @samp{4kp}, @samp{5kc}, @samp{20kc},
+@samp{orion}, and @samp{sb1}. The special value @samp{from-abi} selects the
+most compatible architecture for the selected ABI (that is,
+@samp{mips1} for 32-bit ABIs and @samp{mips3} for 64-bit ABIs)@.
+
+In processor names, a final @samp{000} can be abbreviated as @samp{k}
+(for example, @samp{-march=r2k}). Prefixes are optional, and
+@samp{vr} may be written @samp{r}.
+
+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}},
+where @var{foo} is the capitialized value of @samp{_MIPS_ARCH}@.
+For example, @samp{-march=r2000} will set @samp{_MIPS_ARCH}
+to @samp{"r2000"} and define the macro @samp{_MIPS_ARCH_R2000}.
+
+Note that the @samp{_MIPS_ARCH} macro uses the processor names given
+above. In other words, it will have the full prefix and will not
+abbreviate @samp{000} as @samp{k}. In the case of @samp{from-abi},
+the macro names the resolved architecture (either @samp{"mips1"} or
+@samp{"mips3"}). It names the default architecture when no
+@option{-march} option is given.
+
+@item -mtune=@var{arch}
@opindex mtune
-Assume the defaults for the machine type @var{cpu-type} when scheduling
-instructions. The choices for @var{cpu-type} are @samp{r2000}, @samp{r3000},
-@samp{r3900}, @samp{r4000}, @samp{r4100}, @samp{r4300}, @samp{r4400},
-@samp{r4600}, @samp{r4650}, @samp{r5000}, @samp{r6000}, @samp{r8000},
-and @samp{orion}. Additionally, the @samp{r2000}, @samp{r3000},
-@samp{r4000}, @samp{r5000}, and @samp{r6000} can be abbreviated as
-@samp{r2k} (or @samp{r2K}), @samp{r3k}, etc. While picking a specific
-@var{cpu-type} will schedule things appropriately for that particular
-chip, the compiler will not generate any code that does not meet level 1
-of the MIPS ISA (instruction set architecture) without a @option{-mipsX}
-or @option{-mabi} switch being used.
+Optimize for @var{arch}. Among other things, this option controls
+the way instructions are scheduled, and the perceived cost of arithmetic
+operations. The list of @var{arch} values is the same as for
+@option{-march}.
-@item -mcpu=@var{cpu-type}
-@opindex mcpu
-This is identical to specifying both @option{-march} and @option{-mtune}.
+When this option is not used, GCC will optimize for the processor
+specified by @option{-march}. By using @option{-march} and
+@option{-mtune} together, it is possible to generate code that will
+run on a family of processors, but optimize the code for one
+particular member of that family.
+
+@samp{-mtune} defines the macros @samp{_MIPS_TUNE} and
+@samp{_MIPS_TUNE_@var{foo}}, which work in the same way as the
+@samp{-march} ones described above.
@item -mips1
@opindex mips1
-Issue instructions from level 1 of the MIPS ISA@. This is the default.
-@samp{r3000} is the default @var{cpu-type} at this ISA level.
+Equivalent to @samp{-march=mips1}.
@item -mips2
@opindex mips2
-Issue instructions from level 2 of the MIPS ISA (branch likely, square
-root instructions). @samp{r6000} is the default @var{cpu-type} at this
-ISA level.
+Equivalent to @samp{-march=mips2}.
@item -mips3
@opindex mips3
-Issue instructions from level 3 of the MIPS ISA (64-bit instructions).
-@samp{r4000} is the default @var{cpu-type} at this ISA level.
+Equivalent to @samp{-march=mips3}.
@item -mips4
@opindex mips4
-Issue instructions from level 4 of the MIPS ISA (conditional move,
-prefetch, enhanced FPU instructions). @samp{r8000} is the default
-@var{cpu-type} at this ISA level.
+Equivalent to @samp{-march=mips4}.
-@item -mfp32
-@opindex mfp32
-Assume that 32 32-bit floating point registers are available. This is
-the default.
+@item -mips32
+@opindex mips32
+Equivalent to @samp{-march=mips32}.
-@item -mfp64
-@opindex mfp64
-Assume that 32 64-bit floating point registers are available. This is
-the default when the @option{-mips3} option is used.
+@item -mips64
+@opindex mips64
+Equivalent to @samp{-march=mips64}.
@item -mfused-madd
@itemx -mno-fused-madd
generated by multiply and accumulate instructions cause exceptions
anyway.
+@item -mfp32
+@opindex mfp32
+Assume that floating point registers are 32 bits wide.
+
+@item -mfp64
+@opindex mfp64
+Assume that floating point registers are 64 bits wide.
+
@item -mgp32
@opindex mgp32
-Assume that 32 32-bit general purpose registers are available. This is
-the default.
+Assume that general purpose registers are 32 bits wide.
@item -mgp64
@opindex mgp64
-Assume that 32 64-bit general purpose registers are available. This is
-the default when the @option{-mips3} option is used.
+Assume that general purpose registers are 64 bits wide.
@item -mint64
@opindex mint64
@opindex mlong32
Force long, int, and pointer types to be 32 bits wide.
-If none of @option{-mlong32}, @option{-mlong64}, or @option{-mint64} are set,
-the size of ints, longs, and pointers depends on the ABI and ISA chosen.
-For @option{-mabi=32}, and @option{-mabi=n32}, ints and longs are 32 bits
-wide. For @option{-mabi=64}, ints are 32 bits, and longs are 64 bits wide.
-For @option{-mabi=eabi} and either @option{-mips1} or @option{-mips2}, ints
-and longs are 32 bits wide. For @option{-mabi=eabi} and higher ISAs, ints
-are 32 bits, and longs are 64 bits wide. The width of pointer types is
-the smaller of the width of longs or the width of general purpose
-registers (which in turn depends on the ISA)@.
+The default size of ints, longs and pointers depends on the ABI@. All
+the supported ABIs use 32-bit ints. The n64 ABI uses 64-bit longs, as
+does the 64-bit Cygnus EABI; the others use 32-bit longs. Pointers
+are the same size as longs, or the same size as integer registers,
+whichever is smaller.
@item -mabi=32
@itemx -mabi=o64
@itemx -mabi=n32
@itemx -mabi=64
@itemx -mabi=eabi
+@itemx -mabi=meabi
@opindex mabi=32
@opindex mabi=o64
@opindex mabi=n32
@opindex mabi=64
@opindex mabi=eabi
-Generate code for the indicated ABI@. The default instruction level is
-@option{-mips1} for @samp{32}, @option{-mips3} for @samp{n32}, and
-@option{-mips4} otherwise. Conversely, with @option{-mips1} or
-@option{-mips2}, the default ABI is @samp{32}; otherwise, the default ABI
-is @samp{64}.
+@opindex mabi=meabi
+Generate code for the given ABI@.
+
+Note that there are two embedded ABIs: @option{-mabi=eabi}
+selects the one defined by Cygnus while @option{-meabi=meabi}
+selects the one defined by MIPS@. Both these ABIs have
+32-bit and 64-bit variants. Normally, GCC will generate
+64-bit code when you select a 64-bit architecture, but you
+can use @option{-mgp32} to get 32-bit code instead.
@item -mmips-as
@opindex mmips-as
memory range, and the number 3 (to flush both caches). The default
depends on the target gcc was configured for, but commonly is either
@samp{_flush_func} or @samp{__cpu_flush}.
-@end table
-These options are defined by the macro
-@code{TARGET_SWITCHES} in the machine description. The default for the
-options is also defined by that macro, which enables you to change the
-defaults.
+@item -mbranch-likely
+@itemx -mno-branch-likely
+@opindex mbranch-likely
+@opindex mno-branch-likely
+Enable or disable use of Branch Likely instructions, regardless of the
+default for the selected architecture. By default, Branch Likely
+instructions may be generated if they are supported by the selected
+architecture. An exception is for the MIPS32 and MIPS64 architectures
+and processors which implement those architectures; for those, Branch
+Likely instructions will not be generated by default because the MIPS32
+and MIPS64 architectures specifically deprecate their use.
+@end table
@node i386 and x86-64 Options
@subsection Intel 386 and AMD x86-64 Options
@opindex mno-fancy-math-387
Some 387 emulators do not support the @code{sin}, @code{cos} and
@code{sqrt} instructions for the 387. Specify this option to avoid
-generating those instructions. This option is the default on FreeBSD@.
-As of revision 2.6.1, these instructions are not generated unless you
-also use the @option{-funsafe-math-optimizations} switch.
+generating those instructions. This option is the default on FreeBSD,
+OpenBSD and NetBSD@. This option is overridden when @option{-march}
+indicates that the target cpu will always have an FPU and so the
+instruction will not need emulation. As of revision 2.6.1, these
+instructions are not generated unless you also use the
+@option{-funsafe-math-optimizations} switch.
@item -malign-double
@itemx -mno-align-double
produce code that runs somewhat faster on a @samp{Pentium} at the
expense of more memory.
+@strong{Warning:} if you use the @samp{-malign-double} switch,
+structures containing the above types will be aligned differently than
+the published application binary interface specifications for the 386.
+
@item -m128bit-long-double
@opindex m128bit-long-double
Control the size of @code{long double} type. i386 application binary interface
stack pointer that will not be modified by signal or interrupt handlers
and therefore can be used for temporary data without adjusting the stack
pointer. The flag @option{-mno-red-zone} disables this red zone.
+
+@item -mcmodel=small
+@opindex mcmodel=small
+Generate code for the small code model: the program and its symbols must
+be linked in the lower 2 GB of the address space. Pointers are 64 bits.
+Programs can be statically or dynamically linked. This is the default
+code model.
+
+@item -mcmodel=kernel
+@opindex mcmodel=kernel
+Generate code for the kernel code model. The kernel runs in the
+negative 2 GB of the address space.
+This model has to be used for Linux kernel code.
+
+@item -mcmodel=medium
+@opindex mcmodel=medium
+Generate code for the medium model: The program is linked in the lower 2
+GB of the address space but symbols can be located anywhere in the
+address space. Programs can be statically or dynamically linked, but
+building of shared libraries are not supported with the medium model.
+
+@item -mcmodel=large
+@opindex mcmodel=large
+Generate code for the large model: This model makes no assumptions
+about addresses and sizes of sections. Currently GCC does not implement
+this model.
@end table
@node HPPA Options
@opindex mschedule
Schedule code according to the constraints for the machine type
@var{cpu-type}. The choices for @var{cpu-type} are @samp{700}
-@samp{7100}, @samp{7100LC}, @samp{7200}, and @samp{8000}. Refer to
-@file{/usr/lib/sched.models} on an HP-UX system to determine the
-proper scheduling option for your machine.
+@samp{7100}, @samp{7100LC}, @samp{7200}, @samp{7300} and @samp{8000}. Refer
+to @file{/usr/lib/sched.models} on an HP-UX system to determine the
+proper scheduling option for your machine. The default scheduling is
+@samp{8000}.
@item -mlinker-opt
@opindex mlinker-opt
Generate code suitable for big switch tables. Use this option only if
the assembler/linker complain about out of range branches within a switch
table.
+
+@item -mapp-regs
+@opindex -mapp-regs
+This option will cause r2 and r5 to be used in the code generated by
+the compiler. This setting is the default.
+
+@item -mno-app-regs
+@opindex -mno-app-regs
+This option will cause r2 and r5 to be treated as fixed registers.
+
+@item -mv850e
+@opindex -mv850e
+Specify that the target processor is the V850E. The preprocessor
+constant @samp{__v850e__} will be defined if this option is used.
+
+If neither @option{-mv850} nor @option{-mv850e} are defined
+then a default target processor will be chosen and the relevant
+@samp{__v850*__} preprocessor constant will be defined.
+
+The preprocessor constants @samp{__v850} and @samp{__v851__} are always
+defined, regardless of which processor variant is the target.
+
+@item -mdisable-callt
+@opindex -mdisable-callt
+This option will suppress generation of the CALLT instruction for the
+v850e flavors of the v850 architecture. The default is
+@option{-mno-disable-callt} which allows the CALLT instruction to be used.
+
@end table
@node ARC Options
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries may not be available.
+@item -mieee-compare
+@itemx -mno-ieee-compare
+@opindex mieee-compare
+@opindex mno-ieee-compare
+Control whether or not the compiler uses IEEE floating point
+comparisons. These handle correctly the case where the result of a
+comparison is unordered.
+@strong{Warning:} the requisite kernel support may not be available.
+
@item -mnobitfield
@opindex mnobitfield
Do not use the bit-field instructions. On some machines it is faster to
and fast code, but the number of different data items that can be
addressed is limited. This means that a program that uses lots of static
data may require @option{-mno-base-addresses}.
+
+@item -msingle-exit
+@itemx -mno-single-exit
+@opindex msingle-exit
+@opindex mno-single-exit
+Force (do not force) generated code to have a single exit point in each
+function.
@end table
@node PDP-11 Options
Be warned that you should know what you are doing when invoking this
option, and that not all targets provide complete support for it.
+
+@item -ftls-model=@var{model}
+Alter the thread-local storage model to be used (@pxref{Thread-Local}).
+The @var{model} argument should be one of @code{global-dynamic},
+@code{local-dynamic}, @code{initial-exec} or @code{local-exec}.
+
+The default without @option{-fpic} is @code{initial-exec}; with
+@option{-fpic} the default is @code{global-dynamic}.
@end table
@c man end
libraries for the @option{-l} option (but directories specified with
@option{-L} come first).
-@item C_INCLUDE_PATH
-@itemx CPLUS_INCLUDE_PATH
-@itemx OBJC_INCLUDE_PATH
-@findex C_INCLUDE_PATH
-@findex CPLUS_INCLUDE_PATH
-@findex OBJC_INCLUDE_PATH
-@c @itemx OBJCPLUS_INCLUDE_PATH
-These environment variables pertain to particular languages. Each
-variable's value is a colon-separated list of directories, much like
-@env{PATH}. When GCC searches for header files, it tries the
-directories listed in the variable for the language you are using, after
-the directories specified with @option{-I} but before the standard header
-file directories.
-
-@item DEPENDENCIES_OUTPUT
-@findex DEPENDENCIES_OUTPUT
-@cindex dependencies for make as output
-If this variable is set, its value specifies how to output dependencies
-for Make based on the header files processed by the compiler. This
-output looks much like the output from the @option{-M} option
-(@pxref{Preprocessor Options}), but it goes to a separate file, and is
-in addition to the usual results of compilation.
-
-The value of @env{DEPENDENCIES_OUTPUT} can be just a file name, in
-which case the Make rules are written to that file, guessing the target
-name from the source file name. Or the value can have the form
-@samp{@var{file} @var{target}}, in which case the rules are written to
-file @var{file} using @var{target} as the target name.
-
@item LANG
@findex LANG
@cindex locale definition
recognize and translate multibyte characters.
@end table
+@noindent
+Some additional environments variables affect the behavior of the
+preprocessor.
+
+@include cppenv.texi
+
@c man end
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