-fno-nonansi-builtins -fno-operator-names @gol
-fno-optional-diags -fpermissive @gol
-fno-pretty-templates @gol
--frepo -fno-rtti -fstats -ftemplate-depth-@var{n} @gol
+-frepo -fno-rtti -fstats -ftemplate-depth=@var{n} @gol
-fno-threadsafe-statics -fuse-cxa-atexit -fno-weak -nostdinc++ @gol
-fno-default-inline -fvisibility-inlines-hidden @gol
-fvisibility-ms-compat @gol
-Wno-attributes -Wno-builtin-macro-redefined @gol
-Wc++-compat -Wc++0x-compat -Wcast-align -Wcast-qual @gol
-Wchar-subscripts -Wclobbered -Wcomment @gol
--Wconversion -Wcoverage-mismatch -Wno-deprecated @gol
+-Wconversion -Wcoverage-mismatch -Wcpp -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization @gol
-Wno-div-by-zero -Wempty-body -Wenum-compare -Wno-endif-labels @gol
-Werror -Werror=* @gol
-Wunknown-pragmas -Wno-pragmas @gol
-Wunsuffixed-float-constants -Wunused -Wunused-function @gol
-Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value -Wunused-variable @gol
--Wvariadic-macros -Wvla @gol
+-Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros -Wvla @gol
-Wvolatile-register-var -Wwrite-strings}
@item C and Objective-C-only Warning Options
-frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol
-ftest-coverage -ftime-report -fvar-tracking @gol
--fvar-tracking-assigments -fvar-tracking-assignments-toggle @gol
+-fvar-tracking-assignments -fvar-tracking-assignments-toggle @gol
-g -g@var{level} -gtoggle -gcoff -gdwarf-@var{version} @gol
-ggdb -gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf @gol
-gvms -gxcoff -gxcoff+ @gol
@gccoptlist{-B@var{prefix} -I@var{dir} -iquote@var{dir} -L@var{dir}
-specs=@var{file} -I- --sysroot=@var{dir}}
-@item Target Options
-@c I wrote this xref this way to avoid overfull hbox. -- rms
-@xref{Target Options}.
-@gccoptlist{-V @var{version} -b @var{machine}}
-
@item Machine Dependent Options
@xref{Submodel Options,,Hardware Models and Configurations}.
@c This list is ordered alphanumerically by subsection name.
-fshort-double -fshort-wchar @gol
-fverbose-asm -fpack-struct[=@var{n}] -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
--fno-stack-limit -fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fargument-noalias-anything @gol
+-fno-stack-limit @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
-fvisibility}
@cindex ISO support
@item -ansi
@opindex ansi
-In C mode, this is equivalent to @samp{-std=c89}. In C++ mode, it is
+In C mode, this is equivalent to @samp{-std=c90}. In C++ mode, it is
equivalent to @samp{-std=c++98}.
This turns off certain features of GCC that are incompatible with ISO
Supported by GCC}, for details of these standard versions. This option
is currently only supported when compiling C or C++.
-The compiler can accept several base standards, such as @samp{c89} or
+The compiler can accept several base standards, such as @samp{c90} or
@samp{c++98}, and GNU dialects of those standards, such as
-@samp{gnu89} or @samp{gnu++98}. By specifying a base standard, the
+@samp{gnu90} or @samp{gnu++98}. By specifying a base standard, the
compiler will accept all programs following that standard and those
using GNU extensions that do not contradict it. For example,
-@samp{-std=c89} turns off certain features of GCC that are
+@samp{-std=c90} turns off certain features of GCC that are
incompatible with ISO C90, such as the @code{asm} and @code{typeof}
keywords, but not other GNU extensions that do not have a meaning in
ISO C90, such as omitting the middle term of a @code{?:}
strict-conforming programs may be rejected. The particular standard
is used by @option{-pedantic} to identify which features are GNU
extensions given that version of the standard. For example
-@samp{-std=gnu89 -pedantic} would warn about C++ style @samp{//}
+@samp{-std=gnu90 -pedantic} would warn about C++ style @samp{//}
comments, while @samp{-std=gnu99 -pedantic} would not.
A value for this option must be provided; possible values are
@table @samp
-@item c89
+@item c90
+@itemx c89
@itemx iso9899:1990
Support all ISO C90 programs (certain GNU extensions that conflict
with ISO C90 are disabled). Same as @option{-ansi} for C code.
@w{@uref{http://gcc.gnu.org/c99status.html}} for more information. The
names @samp{c9x} and @samp{iso9899:199x} are deprecated.
-@item gnu89
+@item gnu90
+@itemx gnu89
GNU dialect of ISO C90 (including some C99 features). This
is the default for C code.
The option @option{-fno-gnu89-inline} explicitly tells GCC to use the
C99 semantics for @code{inline} when in C99 or gnu99 mode (i.e., it
specifies the default behavior). This option was first supported in
-GCC 4.3. This option is not supported in C89 or gnu89 mode.
+GCC 4.3. This option is not supported in @option{-std=c90} or
+@option{-std=gnu90} mode.
The preprocessor macros @code{__GNUC_GNU_INLINE__} and
@code{__GNUC_STDC_INLINE__} may be used to check which semantics are
Emit statistics about front-end processing at the end of the compilation.
This information is generally only useful to the G++ development team.
-@item -ftemplate-depth-@var{n}
+@item -ftemplate-depth=@var{n}
@opindex ftemplate-depth
Set the maximum instantiation depth for template classes to @var{n}.
A limit on the template instantiation depth is needed to detect
support such a feature in the near future.
Where the standard specified with @option{-std} represents a GNU
-extended dialect of C, such as @samp{gnu89} or @samp{gnu99}, there is a
+extended dialect of C, such as @samp{gnu90} or @samp{gnu99}, there is a
corresponding @dfn{base standard}, the version of ISO C on which the GNU
extended dialect is based. Warnings from @option{-pedantic} are given
where they are required by the base standard. (It would not make sense
-Wsign-compare @gol
-Wtype-limits @gol
-Wuninitialized @gol
--Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
+-Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
+-Wunused-but-set-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
}
The option @option{-Wextra} also prints warning messages for the
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
This warning is enabled by @option{-Wall}.
+@item -Wno-cpp \
+@r{(C, Objective-C, C++, Objective-C++ and Fortran only)}
+
+Suppress warning messages emitted by @code{#warning} directives.
+
@item -Wformat
@opindex Wformat
@opindex Wno-format
the program (trigraphs within comments are not warned about).
This warning is enabled by @option{-Wall}.
+@item -Wunused-but-set-parameter
+@opindex Wunused-but-set-parameter
+@opindex Wno-unused-but-set-parameter
+Warn whenever a function parameter is assigned to, but otherwise unused
+(aside from its declaration).
+
+To suppress this warning use the @samp{unused} attribute
+(@pxref{Variable Attributes}).
+
+This warning is also enabled by @option{-Wunused} together with
+@option{-Wextra}.
+
+@item -Wunused-but-set-variable
+@opindex Wunused-but-set-variable
+@opindex Wno-unused-but-set-variable
+Warn whenever a local variable is assigned to, but otherwise unused
+(aside from its declaration).
+This warning is enabled by @option{-Wall}.
+
+To suppress this warning use the @samp{unused} attribute
+(@pxref{Variable Attributes}).
+
+This warning is also enabled by @option{-Wunused}, which is enabled
+by @option{-Wall}.
+
@item -Wunused-function
@opindex Wunused-function
@opindex Wno-unused-function
Level 3 (default for @option{-Wstrict-aliasing}):
Should have very few false positives and few false
negatives. Slightly slower than levels 1 or 2 when optimization is enabled.
-Takes care of the common punn+dereference pattern in the frontend:
+Takes care of the common pun+dereference pattern in the frontend:
@code{*(int*)&some_float}.
If optimization is enabled, it also runs in the backend, where it deals
with multiple statement cases using flow-sensitive points-to information.
unsigned integers are disabled by default in C++ unless
@option{-Wsign-conversion} is explicitly enabled.
-@item -Wno-conversion-null @r{(C++)}
+@item -Wno-conversion-null @r{(C++ and Objective-C++ only)}
@opindex Wconversion-null
@opindex Wno-conversion-null
Do not warn for conversions between @code{NULL} and non-pointer
The restrictions on @samp{offsetof} may be relaxed in a future version
of the C++ standard.
-@item -Wno-int-to-pointer-cast @r{(C and Objective-C only)}
+@item -Wno-int-to-pointer-cast
@opindex Wno-int-to-pointer-cast
@opindex Wint-to-pointer-cast
Suppress warnings from casts to pointer type of an integer of a
-different size.
+different size. In C++, casting to a pointer type of smaller size is
+an error. @option{Wint-to-pointer-cast} is enabled by default.
+
@item -Wno-pointer-to-int-cast @r{(C and Objective-C only)}
@opindex Wno-pointer-to-int-cast
using longer strings.
The limit applies @emph{after} string constant concatenation, and does
-not count the trailing NUL@. In C89, the limit was 509 characters; in
+not count the trailing NUL@. In C90, the limit was 509 characters; in
C99, it was raised to 4095. C++98 does not specify a normative
minimum maximum, so we do not diagnose overlength strings in C++@.
In C, emit @code{static} functions that are declared @code{inline}
into the object file, even if the function has been inlined into all
of its callers. This switch does not affect functions using the
-@code{extern inline} extension in GNU C89@. In C++, emit any and all
+@code{extern inline} extension in GNU C90@. In C++, emit any and all
inline functions into the object file.
@item -fkeep-static-consts
Perform loop strip mining transformations on loops. Strip mining
splits a loop into two nested loops. The outer loop has strides
equal to the strip size and the inner loop has strides of the
-original loop within a strip. For example, given a loop like:
+original loop within a strip. The strip length can be changed
+using the @option{loop-block-tile-size} parameter. For example,
+given a loop like:
@smallexample
DO I = 1, N
A(I) = A(I) + C
@end smallexample
loop strip mining will transform the loop as if the user had written:
@smallexample
-DO II = 1, N, 4
- DO I = II, min (II + 3, N)
+DO II = 1, N, 51
+ DO I = II, min (II + 50, N)
A(I) = A(I) + C
ENDDO
ENDDO
@item -floop-block
Perform loop blocking transformations on loops. Blocking strip mines
each loop in the loop nest such that the memory accesses of the
-element loops fit inside caches. For example, given a loop like:
+element loops fit inside caches. The strip length can be changed
+using the @option{loop-block-tile-size} parameter. For example, given
+a loop like:
@smallexample
DO I = 1, N
DO J = 1, M
@end smallexample
loop blocking will transform the loop as if the user had written:
@smallexample
-DO II = 1, N, 64
- DO JJ = 1, M, 64
- DO I = II, min (II + 63, N)
- DO J = JJ, min (JJ + 63, M)
+DO II = 1, N, 51
+ DO JJ = 1, M, 51
+ DO I = II, min (II + 50, N)
+ DO J = JJ, min (JJ + 50, M)
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
was mixing languages before, all you need to add is @option{-flto} to
all the compile and link commands.
+If LTO encounters objects with C linkage declared with incompatible
+types in separate translation units to be linked together (undefined
+behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
+issued. The behavior is still undefined at runtime.
+
If object files containing GIMPLE bytecode are stored in a library
archive, say @file{libfoo.a}, it is possible to extract and use them
in an LTO link if you are using @command{gold} as the linker (which,
@item max-completely-peel-times
The maximum number of iterations of a loop to be suitable for complete peeling.
+@item max-completely-peel-loop-nest-depth
+The maximum depth of a loop nest suitable for complete peeling.
+
@item max-unswitch-insns
The maximum number of insns of an unswitched loop.
@option{ipa-sra-ptr-growth-factor} times the size of the original
pointer parameter.
+@item graphite-max-nb-scop-params
+To avoid exponential effects in the Graphite loop transforms, the
+number of parameters in a Static Control Part (SCoP) is bounded. The
+default value is 10 parameters. A variable whose value is unknown at
+compile time and defined outside a SCoP is a parameter of the SCoP.
+
+@item graphite-max-bbs-per-function
+To avoid exponential effects in the detection of SCoPs, the size of
+the functions analyzed by Graphite is bounded. The default value is
+100 basic blocks.
+
+@item loop-block-tile-size
+Loop blocking or strip mining transforms, enabled with
+@option{-floop-block} or @option{-floop-strip-mine}, strip mine each
+loop in the loop nest by a given number of iterations. The strip
+length can be changed using the @option{loop-block-tile-size}
+parameter. The default value is 51 iterations.
+
@end table
@end table
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.
-
-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
-example, if a cross-compiler was configured with @samp{configure
-arm-elf}, meaning to compile for an arm processor with elf binaries,
-then you would specify @option{-b arm-elf} to run that cross compiler.
-Because there are other options beginning with @option{-b}, the
-configuration must contain a hyphen, or @option{-b} alone should be one
-argument followed by the configuration in the next argument.
-
-@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{4.0}, meaning to run GCC version 4.0.
-@end table
-
-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.
+was installed last.
@node Submodel Options
@section Hardware Models and Configurations
@cindex hardware models and configurations, specifying
@cindex machine dependent options
-Earlier we discussed the standard option @option{-b} which chooses among
-different installed compilers for completely different target
-machines, such as VAX vs.@: 68000 vs.@: 80386.
-
-In addition, each of these target machine types can have its own
+Each target machine types can have its own
special options, starting with @samp{-m}, to choose among various
hardware models or configurations---for example, 68010 vs 68020,
floating coprocessor or none. A single installed version of the
@item k6
AMD K6 CPU with MMX instruction set support.
@item k6-2, k6-3
-Improved versions of AMD K6 CPU with MMX and 3dNOW!@: instruction set support.
+Improved versions of AMD K6 CPU with MMX and 3DNow!@: instruction set support.
@item athlon, athlon-tbird
-AMD Athlon CPU with MMX, 3dNOW!, enhanced 3dNOW!@: and SSE prefetch instructions
+AMD Athlon CPU with MMX, 3dNOW!, enhanced 3DNow!@: and SSE prefetch instructions
support.
@item athlon-4, athlon-xp, athlon-mp
-Improved AMD Athlon CPU with MMX, 3dNOW!, enhanced 3dNOW!@: and full SSE
+Improved AMD Athlon CPU with MMX, 3DNow!, enhanced 3DNow!@: and full SSE
instruction set support.
@item k8, opteron, athlon64, athlon-fx
AMD K8 core based CPUs with x86-64 instruction set support. (This supersets
-MMX, SSE, SSE2, 3dNOW!, enhanced 3dNOW!@: and 64-bit instruction set extensions.)
+MMX, SSE, SSE2, 3DNow!, enhanced 3DNow!@: and 64-bit instruction set extensions.)
@item k8-sse3, opteron-sse3, athlon64-sse3
Improved versions of k8, opteron and athlon64 with SSE3 instruction set support.
@item amdfam10, barcelona
AMD Family 10h core based CPUs with x86-64 instruction set support. (This
-supersets MMX, SSE, SSE2, SSE3, SSE4A, 3dNOW!, enhanced 3dNOW!, ABM and 64-bit
+supersets MMX, SSE, SSE2, SSE3, SSE4A, 3DNow!, enhanced 3DNow!, ABM and 64-bit
instruction set extensions.)
@item winchip-c6
IDT Winchip C6 CPU, dealt in same way as i486 with additional MMX instruction
set support.
@item winchip2
-IDT Winchip2 CPU, dealt in same way as i486 with additional MMX and 3dNOW!@:
+IDT Winchip2 CPU, dealt in same way as i486 with additional MMX and 3DNow!@:
instruction set support.
@item c3
-Via C3 CPU with MMX and 3dNOW!@: instruction set support. (No scheduling is
+Via C3 CPU with MMX and 3DNow!@: instruction set support. (No scheduling is
implemented for this chip.)
@item c3-2
Via C3-2 CPU with MMX and SSE instruction set support. (No scheduling is
implemented for this chip.)
@item geode
-Embedded AMD CPU with MMX and 3dNOW! instruction set support.
+Embedded AMD CPU with MMX and 3DNow!@: instruction set support.
@end table
While picking a specific @var{cpu-type} will schedule things appropriately
@item -mmax-constant-size=@var{N}
@opindex mmax-constant-size
-Specifies the maxium size, in bytes, of a constant that can be used as
+Specifies the maximum size, in bytes, of a constant that can be used as
an operand in a RX instruction. Although the RX instruction set does
allow constants of up to 4 bytes in length to be used in instructions,
a longer value equates to a longer instruction. Thus in some
@opindex mint-register
Specify the number of registers to reserve for fast interrupt handler
functions. The value @var{N} can be between 0 and 4. A value of 1
-means that register @code{r13} will be reserved for ther exclusive use
+means that register @code{r13} will be reserved for the exclusive use
of fast interrupt handlers. A value of 2 reserves @code{r13} and
@code{r12}. A value of 3 reserves @code{r13}, @code{r12} and
@code{r11}, and a value of 4 reserves @code{r13} through @code{r10}.
@option{-Wl,--defsym,__stack_limit=0x7ffe0000} to enforce a stack limit
of 128KB@. Note that this may only work with the GNU linker.
-@cindex aliasing of parameters
-@cindex parameters, aliased
-@item -fargument-alias
-@itemx -fargument-noalias
-@itemx -fargument-noalias-global
-@itemx -fargument-noalias-anything
-@opindex fargument-alias
-@opindex fargument-noalias
-@opindex fargument-noalias-global
-@opindex fargument-noalias-anything
-Specify the possible relationships among parameters and between
-parameters and global data.
-
-@option{-fargument-alias} specifies that arguments (parameters) may
-alias each other and may alias global storage.@*
-@option{-fargument-noalias} specifies that arguments do not alias
-each other, but may alias global storage.@*
-@option{-fargument-noalias-global} specifies that arguments do not
-alias each other and do not alias global storage.
-@option{-fargument-noalias-anything} specifies that arguments do not
-alias any other storage.
-
-Each language will automatically use whatever option is required by
-the language standard. You should not need to use these options yourself.
-
@item -fleading-underscore
@opindex fleading-underscore
This option and its counterpart, @option{-fno-leading-underscore}, forcibly
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