@c man end
+@xref{Option Index}, for an index to GCC's options.
+
@menu
* Option Summary:: Brief list of all options, without explanations.
* Overall Options:: Controlling the kind of output:
Any file name with no recognized suffix is treated this way.
@end table
+@opindex x
You can specify the input language explicitly with the @samp{-x} option:
@table @gcctabopt
has not been used at all).
@item -pass-exit-codes
+@opindex pass-exit-codes
Normally the @command{gcc} program will exit with the code of 1 if any
phase of the compiler returns a non-success return code. If you specify
@samp{-pass-exit-codes}, the @command{gcc} program will instead return with
@table @gcctabopt
@item -c
+@opindex c
Compile or assemble the source files, but do not link. The linking
stage simply is not done. The ultimate output is in the form of an
object file for each source file.
ignored.
@item -S
+@opindex S
Stop after the stage of compilation proper; do not assemble. The output
is in the form of an assembler code file for each non-assembler input
file specified.
Input files that don't require compilation are ignored.
@item -E
+@opindex E
Stop after the preprocessing stage; do not run the compiler proper. The
output is in the form of preprocessed source code, which is sent to the
standard output.
@cindex output file option
@item -o @var{file}
+@opindex o
Place output in file @var{file}. This applies regardless to whatever
sort of output is being produced, whether it be an executable file,
an object file, an assembler file or preprocessed C code.
all preprocessed C source on standard output.@refill
@item -v
+@opindex v
Print (on standard error output) the commands executed to run the stages
of compilation. Also print the version number of the compiler driver
program and of the preprocessor and the compiler proper.
@item -pipe
+@opindex pipe
Use pipes rather than temporary files for communication between the
various stages of compilation. This fails to work on some systems where
the assembler is unable to read from a pipe; but the GNU assembler has
no trouble.
@item --help
+@opindex help
Print (on the standard output) a description of the command line options
understood by @command{gcc}. If the @option{-v} option is also specified
then @option{--help} will also be passed on to the various processes
be displayed.
@item --target-help
+@opindex target-help
Print (on the standard output) a description of target specific command
line options for each tool.
@end table
@cindex ANSI support
@cindex ISO support
@item -ansi
+@opindex ansi
In C mode, support all ISO C89 programs. In C++ mode,
remove GNU extensions that conflict with ISO C++.
affected.
@item -std=
+@opindex std
Determine the language standard. A value for this option must be provided;
possible values are
these standard versions.
@item -fno-asm
+@opindex fno-asm
Do not recognize @code{asm}, @code{inline} or @code{typeof} as a
keyword, so that code can use these words as identifiers. You can use
the keywords @code{__asm__}, @code{__inline__} and @code{__typeof__}
@code{inline} is a standard keyword in ISO C99.
@item -fno-builtin
+@opindex fno-builtin
@cindex builtin functions
Don't recognize builtin functions that do not begin with
@samp{__builtin_} as prefix. @xref{Other Builtins,,Other built-in
@code{std::strchr}), so that you automatically get efficient code.
@item -fhosted
+@opindex fhosted
@cindex hosted environment
Assert that compilation takes place in a hosted environment. This implies
This is equivalent to @samp{-fno-freestanding}.
@item -ffreestanding
+@opindex ffreestanding
@cindex hosted environment
Assert that compilation takes place in a freestanding environment. This
freestanding and hosted environments.
@item -trigraphs
+@opindex trigraphs
Support ISO C trigraphs. You don't want to know about this
brain-damage. The @option{-ansi} option (and @option{-std} options for
strict ISO C conformance) implies @option{-trigraphs}.
@cindex traditional C language
@cindex C language, traditional
@item -traditional
+@opindex traditional
Attempt to support some aspects of traditional C compilers.
Specifically:
not declared @code{volatile} may be clobbered.
@item
-@kindex \x
-@kindex \a
+@cindex @samp{\x}
+@cindex @samp{\a}
@cindex escape sequences, traditional
The character escape sequences @samp{\x} and @samp{\a} evaluate as the
literal characters @samp{x} and @samp{a} respectively. Without
which is described next.
@item -traditional-cpp
+@opindex traditional-cpp
Attempt to support some aspects of traditional C preprocessors.
Specifically:
@end itemize
@item -fcond-mismatch
+@opindex fcond-mismatch
Allow conditional expressions with mismatched types in the second and
third arguments. The value of such an expression is void. This option
is not supported for C++.
@item -funsigned-char
+@opindex funsigned-char
Let the type @code{char} be unsigned, like @code{unsigned char}.
Each kind of machine has a default for what @code{char} should
is always just like one of those two.
@item -fsigned-char
+@opindex fsigned-char
Let the type @code{char} be signed, like @code{signed char}.
Note that this is equivalent to @samp{-fno-unsigned-char}, which is
@itemx -funsigned-bitfields
@itemx -fno-signed-bitfields
@itemx -fno-unsigned-bitfields
+@opindex fsigned-bitfields
+@opindex funsigned-bitfields
+@opindex fno-signed-bitfields
+@opindex fno-unsigned-bitfields
These options control whether a bitfield is signed or unsigned, when the
declaration does not use either @code{signed} or @code{unsigned}. By
default, such a bitfield is signed, because this is consistent: the
no matter what.
@item -fwritable-strings
+@opindex fwritable-strings
Store string constants in the writable data segment and don't uniquize
them. This is for compatibility with old programs which assume they can
write into string constants. The option @samp{-traditional} also has
be constant.
@item -fallow-single-precision
+@opindex fallow-single-precision
Do not promote single precision math operations to double precision,
even when compiling with @samp{-traditional}.
with ISO or GNU C conventions (the default).
@item -fshort-wchar
+@opindex fshort-wchar
Override the underlying type for @samp{wchar_t} to be @samp{short
unsigned int} instead of the default for the target. This option is
useful for building programs to run under WINE.
@table @gcctabopt
@item -fno-access-control
+@opindex fno-access-control
Turn off all access checking. This switch is mainly useful for working
around bugs in the access control code.
@item -fcheck-new
+@opindex fcheck-new
Check that the pointer returned by @code{operator new} is non-null
before attempting to modify the storage allocated. The current Working
Paper requires that @code{operator new} never return a null pointer, so
(nothrow)}.
@item -fconserve-space
+@opindex fconserve-space
Put uninitialized or runtime-initialized global variables into the
common segment, as C does. This saves space in the executable at the
cost of not diagnosing duplicate definitions. If you compile with this
been added for putting variables into BSS without making them common.
@item -fno-const-strings
+@opindex fno-const-strings
Give string constants type @code{char *} instead of type @code{const
char *}. By default, G++ uses type @code{const char *} as required by
the standard. Even if you use @samp{-fno-const-strings}, you cannot
string constants that have type @code{const char *}.
@item -fdollars-in-identifiers
+@opindex fdollars-in-identifiers
Accept @samp{$} in identifiers. You can also explicitly prohibit use of
@samp{$} with the option @samp{-fno-dollars-in-identifiers}. (GNU C allows
@samp{$} by default on most target systems, but there are a few exceptions.)
identifiers. However, ISO C and C++ forbid @samp{$} in identifiers.
@item -fno-elide-constructors
+@opindex fno-elide-constructors
The C++ standard allows an implementation to omit creating a temporary
which is only used to initialize another object of the same type.
Specifying this option disables that optimization, and forces g++ to
call the copy constructor in all cases.
@item -fno-enforce-eh-specs
+@opindex fno-enforce-eh-specs
Don't check for violation of exception specifications at runtime. This
option violates the C++ standard, but may be useful for reducing code
size in production builds, much like defining @samp{NDEBUG}. The compiler
will still optimize based on the exception specifications.
@item -fexternal-templates
+@opindex fexternal-templates
Cause template instantiations to obey @samp{#pragma interface} and
@samp{implementation}; template instances are emitted or not according
to the location of the template definition. @xref{Template
This option is deprecated.
@item -falt-external-templates
+@opindex falt-external-templates
Similar to -fexternal-templates, but template instances are emitted or
not according to the place where they are first instantiated.
@xref{Template Instantiation}, for more information.
@item -ffor-scope
@itemx -fno-for-scope
+@opindex ffor-scope
+@opindex fno-for-scope
If -ffor-scope is specified, the scope of variables declared in
a @i{for-init-statement} is limited to the @samp{for} loop itself,
as specified by the C++ standard.
otherwise be invalid, or have different behavior.
@item -fno-gnu-keywords
+@opindex fno-gnu-keywords
Do not recognize @code{typeof} as a keyword, so that code can use this
word as an identifier. You can use the keyword @code{__typeof__} instead.
@samp{-ansi} implies @samp{-fno-gnu-keywords}.
@item -fhonor-std
+@opindex fhonor-std
Treat the @code{namespace std} as a namespace, instead of ignoring
it. For compatibility with earlier versions of g++, the compiler will,
by default, ignore @code{namespace-declarations},
@code{namespace-names}, if they involve @code{std}.
@item -fno-implicit-templates
+@opindex fno-implicit-templates
Never emit code for non-inline templates which are instantiated
implicitly (i.e. by use); only emit code for explicit instantiations.
@xref{Template Instantiation}, for more information.
@item -fno-implicit-inline-templates
+@opindex fno-implicit-inline-templates
Don't emit code for implicit instantiations of inline templates, either.
The default is to handle inlines differently so that compiles with and
without optimization will need the same set of explicit instantiations.
@item -fno-implement-inlines
+@opindex fno-implement-inlines
To save space, do not emit out-of-line copies of inline functions
controlled by @samp{#pragma implementation}. This will cause linker
errors if these functions are not inlined everywhere they are called.
@item -fms-extensions
+@opindex fms-extensions
Disable pedantic warnings about constructs used in MFC, such as implicit
int and getting a pointer to member function via non-standard syntax.
@item -fno-nonansi-builtins
+@opindex fno-nonansi-builtins
Disable builtin declarations of functions that are not mandated by
ANSI/ISO C. These include @code{ffs}, @code{alloca}, @code{_exit},
@code{index}, @code{bzero}, @code{conjf}, and other related functions.
@item -fno-operator-names
+@opindex fno-operator-names
Do not treat the operator name keywords @code{and}, @code{bitand},
@code{bitor}, @code{compl}, @code{not}, @code{or} and @code{xor} as
synonyms as keywords.
@item -fno-optional-diags
+@opindex fno-optional-diags
Disable diagnostics that the standard says a compiler does not need to
issue. Currently, the only such diagnostic issued by g++ is the one for
a name having multiple meanings within a class.
@item -fpermissive
+@opindex fpermissive
Downgrade messages about nonconformant code from errors to warnings. By
default, g++ effectively sets @samp{-pedantic-errors} without
@samp{-pedantic}; this option reverses that. This behavior and this
option are superseded by @samp{-pedantic}, which works as it does for GNU C.
@item -frepo
+@opindex frepo
Enable automatic template instantiation. This option also implies
@samp{-fno-implicit-templates}. @xref{Template Instantiation}, for more
information.
@item -fno-rtti
+@opindex fno-rtti
Disable generation of information about every class with virtual
functions for use by the C++ runtime type identification features
(@samp{dynamic_cast} and @samp{typeid}). If you don't use those parts
needed.
@item -fstats
+@opindex fstats
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}
+@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
endless recursions during template class instantiation. ANSI/ISO C++
conforming programs must not rely on a maximum depth greater than 17.
@item -fuse-cxa-atexit
+@opindex fuse-cxa-atexit
Register destructors for objects with static storage duration with the
@code{__cxa_atexit} function rather than the @code{atexit} function.
This option is required for fully standards-compliant handling of static
@code{__cxa_atexit}.
@item -fvtable-gc
+@opindex fvtable-gc
Emit special relocations for vtables and virtual function references
so that the linker can identify unused virtual functions and zero out
vtable slots that refer to them. This is most useful with
this option. @samp{-Wl,--gc-sections} is ignored without @samp{-static}.
@item -fno-weak
+@opindex fno-weak
Do not use weak symbol support, even if it is provided by the linker.
By default, G++ will use weak symbols if they are available. This
option exists only for testing, and should not be used by end-users;
be removed in a future release of G++.
@item -nostdinc++
+@opindex nostdinc++
Do not search for header files in the standard directories specific to
C++, but do still search the other standard directories. (This option
is used when building the C++ library.)
@table @gcctabopt
@item -fno-default-inline
+@opindex fno-default-inline
Do not assume @samp{inline} for functions defined inside a class scope.
@xref{Optimize Options,,Options That Control Optimization}. Note that these
functions will have linkage like inline functions; they just won't be
inlined by default.
@item -Wctor-dtor-privacy (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.
@item -Wnon-virtual-dtor (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.
@item -Wreorder (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
@table @gcctabopt
@item -Weffc++ (C++ only)
+@opindex Weffc++
Warn about violations of various style guidelines from Scott Meyers'
@cite{Effective C++} books. If you use this option, you should be aware
that the standard library headers do not obey all of these guidelines;
you can use @samp{grep -v} to filter out those warnings.
@item -Wno-deprecated (C++ only)
+@opindex Wno-deprecated
Do not warn about usage of deprecated features. @xref{Deprecated Features}.
@item -Wno-non-template-friend (C++ only)
+@opindex Wno-non-template-friend
Disable warnings when non-templatized friend functions are declared
within a template. With the advent of explicit template specification
support in g++, if the name of the friend is an unqualified-id (ie,
but disables the helpful warning.
@item -Wold-style-cast (C++ only)
+@opindex Wold-style-cast
Warn if an old-style (C-style) cast is used within a C++ program. The
new-style casts (@samp{static_cast}, @samp{reinterpret_cast}, and
@samp{const_cast}) are less vulnerable to unintended effects, and much
easier to grep for.
@item -Woverloaded-virtual (C++ only)
+@opindex Woverloaded-virtual
@cindex overloaded virtual fn, warning
@cindex warning for overloaded virtual fn
Warn when a function declaration hides virtual functions from a
will fail to compile.
@item -Wno-pmf-conversions (C++ only)
+@opindex Wno-pmf-conversions
Disable the diagnostic for converting a bound pointer to member function
to a plain pointer.
@item -Wsign-promo (C++ only)
+@opindex Wsign-promo
Warn when overload resolution chooses a promotion from unsigned or
enumeral type to a signed type over a conversion to an unsigned type of
the same size. Previous versions of g++ would try to preserve
unsignedness, but the standard mandates the current behavior.
@item -Wsynth (C++ only)
+@opindex Wsynth
@cindex warning for synthesized methods
@cindex synthesized methods, warning
Warn when g++'s synthesis behavior does not match that of cfront. For
@table @gcctabopt
@item -fconstant-string-class=@var{class name}
+@opindex fconstant-string-class
Use @var{class name} as the name of the class to instantiate for each
literal string specified with the syntax @code{@@"..."}. The default
class name is @code{NXConstantString}.
@item -fgnu-runtime
+@opindex fgnu-runtime
Generate object code compatible with the standard GNU Objective-C
runtime. This is the default for most types of systems.
@item -fnext-runtime
+@opindex fnext-runtime
Generate output compatible with the NeXT runtime. This is the default
for NeXT-based systems, including Darwin and Mac OS X.
@item -gen-decls
+@opindex gen-decls
Dump interface declarations for all classes seen in the source file to a
file named @file{@var{sourcename}.decl}.
@item -Wno-protocol
+@opindex Wno-protocol
Do not warn if methods required by a protocol are not implemented
in the class adopting it.
@item -Wselector
+@opindex Wselector
Warn if a selector has multiple methods of different types defined.
@c not documented because only avail via -Wp
@table @gcctabopt
@item -fmessage-length=@var{n}
+@opindex fmessage-length
Try to format error messages so that they fit on lines of about @var{n}
characters. The default is 72 characters for g++ and 0 for the rest of
the front-ends supported by GCC. If @var{n} is zero, then no
line-wrapping will be done; each error message will appear on a single
line.
+@opindex fdiagnostics-show-location
@item -fdiagnostics-show-location=once
Only meaningful in line-wrapping mode. Instructs the diagnostic messages
reporter to emit @emph{once} source location information; that is, in
@table @gcctabopt
@cindex syntax checking
@item -fsyntax-only
+@opindex fsyntax-only
Check the code for syntax errors, but don't do anything beyond that.
@item -pedantic
+@opindex pedantic
Issue all the warnings demanded by strict ISO C and ISO C++;
reject all programs that use forbidden extensions, and some other
programs that do not follow ISO C and ISO C++. For ISO C, follows the
nothing to warn about.)
@item -pedantic-errors
+@opindex pedantic-errors
Like @samp{-pedantic}, except that errors are produced rather than
warnings.
@item -w
+@opindex w
Inhibit all warning messages.
@item -Wno-import
+@opindex Wno-import
Inhibit warning messages about the use of @samp{#import}.
@item -Wchar-subscripts
+@opindex Wchar-subscripts
Warn if an array subscript has type @code{char}. This is a common cause
of error, as programmers often forget that this type is signed on some
machines.
@item -Wcomment
+@opindex Wcomment
Warn whenever a comment-start sequence @samp{/*} appears in a @samp{/*}
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
@item -Wformat
+@opindex Wformat
Check calls to @code{printf} and @code{scanf}, etc., to make sure that
the arguments supplied have types appropriate to the format string
specified, and that the conversions specified in the format string make
not included in @samp{-Wall}.
@item -Wno-format-y2k
+@opindex Wno-format-y2k
If @samp{-Wformat} is specified, do not warn about @code{strftime}
formats which may yield only a two-digit year.
@item -Wno-format-extra-args
+@opindex Wno-format-extra-args
If @samp{-Wformat} is specified, do not warn about excess arguments to a
@code{printf} or @code{scanf} format function. The C standard specifies
that such arguments are ignored.
@item -Wformat-nonliteral
+@opindex Wformat-nonliteral
If @samp{-Wformat} is specified, also warn if the format string is not a
string literal and so cannot be checked, unless the format function
takes its format arguments as a @code{va_list}.
@item -Wformat-security
+@opindex Wformat-security
If @samp{-Wformat} is specified, also warn about uses of format
functions that represent possible security problems. At present, this
warns about calls to @code{printf} and @code{scanf} functions where the
included in @samp{-Wformat-nonliteral}.)
@item -Wformat=2
+@opindex Wformat=2
Enable @samp{-Wformat} plus format checks not included in
@samp{-Wformat}. Currently equivalent to @samp{-Wformat
-Wformat-nonliteral -Wformat-security}.
@item -Wimplicit-int
+@opindex Wimplicit-int
Warn when a declaration does not specify a type.
@item -Wimplicit-function-declaration
@itemx -Werror-implicit-function-declaration
+@opindex Wimplicit-function-declaration
+@opindex Werror-implicit-function-declaration
Give a warning (or error) whenever a function is used before being
declared.
@item -Wimplicit
+@opindex Wimplicit
Same as @samp{-Wimplicit-int} and @samp{-Wimplicit-function-}@*
@samp{declaration}.
@item -Wmain
+@opindex Wmain
Warn if the type of @samp{main} is suspicious. @samp{main} should be a
function with external linkage, returning int, taking either zero
arguments, two, or three arguments of appropriate types.
@item -Wmissing-braces
+@opindex Wmissing-braces
Warn if an aggregate or union initializer is not fully bracketed. In
the following example, the initializer for @samp{a} is not fully
bracketed, but that for @samp{b} is fully bracketed.
@end smallexample
@item -Wmultichar
+@opindex Wmultichar
Warn if a multicharacter constant (@samp{'FOOF'}) is used. Usually they
indicate a typo in the user's code, as they have implementation-defined
values, and should not be used in portable code.
@item -Wparentheses
+@opindex Wparentheses
Warn if parentheses are omitted in certain contexts, such
as when there is an assignment in a context where a truth value
is expected, or when operators are nested whose precedence people
@end smallexample
@item -Wsequence-point
+@opindex Wsequence-point
Warn about code that may have undefined semantics because of violations
of sequence point rules in the C standard.
@w{@uref{http://gcc.gnu.org/readings.html}}.
@item -Wreturn-type
+@opindex Wreturn-type
Warn whenever a function is defined with a return-type that defaults to
@code{int}. Also warn about any @code{return} statement with no
return-value in a function whose return-type is not @code{void}.
exceptions are @samp{main} and functions defined in system headers.
@item -Wswitch
+@opindex Wswitch
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. (The presence of a @code{default} label prevents this
provoke warnings when this option is used.
@item -Wtrigraphs
+@opindex Wtrigraphs
Warn if any trigraphs are encountered that might change the meaning of
the program (trigraphs within comments are not warned about).
@item -Wunused-function
+@opindex Wunused-function
Warn whenever a static function is declared but not defined or a
non\-inline static function is unused.
@item -Wunused-label
+@opindex Wunused-label
Warn whenever a label is declared but not used.
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
@item -Wunused-parameter
+@opindex Wunused-parameter
Warn whenever a function parameter is unused aside from its declaration.
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
@item -Wunused-variable
+@opindex Wunused-variable
Warn whenever a local variable or non-constant static variable is unused
aside from its declaration
(@pxref{Variable Attributes}).
@item -Wunused-value
+@opindex Wunused-value
Warn whenever a statement computes a result that is explicitly not used.
To suppress this warning cast the expression to @samp{void}.
@item -Wunused
+@opindex Wunused
All all the above @samp{-Wunused} options combined.
In order to get a warning about an unused function parameter, you must
@samp{-Wunused-parameter}.
@item -Wuninitialized
+@opindex Wuninitialized
Warn if an automatic variable is used without first being initialized or
if a variable may be clobbered by a @code{setjmp} call.
Attributes}.
@item -Wreorder (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
@cindex unknown pragmas, warning
@cindex pragmas, warning of unknown
the warnings were only enabled by the @samp{-Wall} command line option.
@item -Wall
+@opindex Wall
All of the above @samp{-W} options combined. This enables all the
warnings about constructions that some users consider questionable, and
that are easy to avoid (or modify to prevent the warning), even in
conjunction with macros.
@item -Wsystem-headers
+@opindex Wsystem-headers
@cindex warnings from system headers
@cindex system headers, warnings from
Print warning messages for constructs found in system header files.
@table @gcctabopt
@item -W
+@opindex W
Print extra warning messages for these events:
@itemize @bullet
@end itemize
@item -Wfloat-equal
+@opindex Wfloat-equal
Warn if floating point values are used in equality comparisons.
The idea behind this is that sometimes it is convenient (for the
probably mistaken.
@item -Wtraditional (C only)
+@opindex Wtraditional
Warn about certain constructs that behave differently in traditional and
ISO C. Also warn about ISO C constructs that have no traditional C
equivalent, and/or problematic constructs which should be avoided.
@end itemize
@item -Wundef
+@opindex Wundef
Warn if an undefined identifier is evaluated in an @samp{#if} directive.
@item -Wshadow
+@opindex Wshadow
Warn whenever a local variable shadows another local variable, parameter or
global variable or whenever a built-in function is shadowed.
@item -Wlarger-than-@var{len}
+@opindex Wlarger-than
Warn whenever an object of larger than @var{len} bytes is defined.
@item -Wpointer-arith
+@opindex Wpointer-arith
Warn about anything that depends on the ``size of'' a function type or
of @code{void}. GNU C assigns these types a size of 1, for
convenience in calculations with @code{void *} pointers and pointers
to functions.
@item -Wbad-function-cast (C only)
+@opindex Wbad-function-cast
Warn whenever a function call is cast to a non-matching type.
For example, warn if @code{int malloc()} is cast to @code{anything *}.
@item -Wcast-qual
+@opindex Wcast-qual
Warn whenever a pointer is cast so as to remove a type qualifier from
the target type. For example, warn if a @code{const char *} is cast
to an ordinary @code{char *}.
@item -Wcast-align
+@opindex Wcast-align
Warn whenever a pointer is cast such that the required alignment of the
target is increased. For example, warn if a @code{char *} is cast to
an @code{int *} on machines where integers can only be accessed at
two- or four-byte boundaries.
@item -Wwrite-strings
+@opindex Wwrite-strings
Give string constants the type @code{const char[@var{length}]} so that
copying the address of one into a non-@code{const} @code{char *}
pointer will get a warning. These warnings will help you find at
this is why we did not make @samp{-Wall} request these warnings.
@item -Wconversion
+@opindex Wconversion
Warn if a prototype causes a type conversion that is different from what
would happen to the same argument in the absence of a prototype. This
includes conversions of fixed point to floating and vice versa, and
casts like @code{(unsigned) -1}.
@item -Wsign-compare
+@opindex Wsign-compare
@cindex warning for comparison of signed and unsigned values
@cindex comparison of signed and unsigned values, warning
@cindex signed and unsigned values, comparison warning
of @samp{-W} without this warning, use @samp{-W -Wno-sign-compare}.
@item -Waggregate-return
+@opindex Waggregate-return
Warn if any functions that return structures or unions are defined or
called. (In languages where you can return an array, this also elicits
a warning.)
@item -Wstrict-prototypes (C only)
+@opindex Wstrict-prototypes
Warn if a function is declared or defined without specifying the
argument types. (An old-style function definition is permitted without
a warning if preceded by a declaration which specifies the argument
types.)
@item -Wmissing-prototypes (C only)
+@opindex Wmissing-prototypes
Warn if a global function is defined without a previous prototype
declaration. This warning is issued even if the definition itself
provides a prototype. The aim is to detect global functions that fail
to be declared in header files.
@item -Wmissing-declarations
+@opindex Wmissing-declarations
Warn if a global function is defined without a previous declaration.
Do so even if the definition itself provides a prototype.
Use this option to detect global functions that are not declared in
header files.
@item -Wmissing-noreturn
+@opindex Wmissing-noreturn
Warn about functions which might be candidates for attribute @code{noreturn}.
Note these are only possible candidates, not absolute ones. Care should
be taken to manually verify functions actually do not ever return before
hosted C environments.
@item -Wmissing-format-attribute
+@opindex Wmissing-format-attribute
+@opindex Wformat
If @samp{-Wformat} is enabled, also warn about functions which might be
candidates for @code{format} attributes. Note these are only possible
candidates, not absolute ones. GCC will guess that @code{format}
@samp{-Wformat} is enabled (possibly by @samp{-Wall}).
@item -Wpacked
+@opindex Wpacked
Warn if a structure is given the packed attribute, but the packed
attribute has no effect on the layout or size of the structure.
Such structures may be mis-aligned for little benefit. For
@end smallexample
@item -Wpadded
+@opindex Wpadded
Warn if padding is included in a structure, either to align an element
of the structure or to align the whole structure. Sometimes when this
happens it is possible to rearrange the fields of the structure to
reduce the padding and so make the structure smaller.
@item -Wredundant-decls
+@opindex Wredundant-decls
Warn if anything is declared more than once in the same scope, even in
cases where multiple declaration is valid and changes nothing.
@item -Wnested-externs (C only)
+@opindex Wnested-externs
Warn if an @code{extern} declaration is encountered within a function.
@item -Wunreachable-code
+@opindex Wunreachable-code
Warn if the compiler detects that code will never be executed.
This option is intended to warn when the compiler detects that at
code is to provide behaviour which is selectable at compile-time.
@item -Winline
+@opindex Winline
Warn if a function can not be inlined and it was declared as inline.
@item -Wlong-long
+@opindex Wlong-long
+@opindex Wno-long-long
Warn if @samp{long long} type is used. This is default. To inhibit
the warning messages, use @samp{-Wno-long-long}. Flags
@samp{-Wlong-long} and @samp{-Wno-long-long} are taken into account
only when @samp{-pedantic} flag is used.
@item -Wdisabled-optimization
+@opindex Wdisabled-optimization
Warn if a requested optimization pass is disabled. This warning does
not generally indicate that there is anything wrong with your code; it
merely indicates that GCC's optimizers were unable to handle the code
itself is likely to take inordinate amounts of time.
@item -Werror
+@opindex Werror
Make all warnings into errors.
@end table
@table @gcctabopt
@item -g
+@opindex g
Produce debugging information in the operating system's native format
(stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging
information.
capability for more than one debugging format.
@item -ggdb
+@opindex ggdb
Produce debugging information for use by GDB. This means to use the
most expressive format available (DWARF 2, stabs, or the native format
if neither of those are supported), including GDB extensions if at all
possible.
@item -gstabs
+@opindex gstabs
Produce debugging information in stabs format (if that is supported),
without GDB extensions. This is the format used by DBX on most BSD
systems. On MIPS, Alpha and System V Release 4 systems this option
On System V Release 4 systems this option requires the GNU assembler.
@item -gstabs+
+@opindex gstabs+
Produce debugging information in stabs format (if that is supported),
using GNU extensions understood only by the GNU debugger (GDB). The
use of these extensions is likely to make other debuggers crash or
refuse to read the program.
@item -gcoff
+@opindex gcoff
Produce debugging information in COFF format (if that is supported).
This is the format used by SDB on most System V systems prior to
System V Release 4.
@item -gxcoff
+@opindex gxcoff
Produce debugging information in XCOFF format (if that is supported).
This is the format used by the DBX debugger on IBM RS/6000 systems.
@item -gxcoff+
+@opindex gxcoff+
Produce debugging information in XCOFF format (if that is supported),
using GNU extensions understood only by the GNU debugger (GDB). The
use of these extensions is likely to make other debuggers crash or
assembler (GAS) to fail with an error.
@item -gdwarf
+@opindex gdwarf
Produce debugging information in DWARF version 1 format (if that is
supported). This is the format used by SDB on most System V Release 4
systems.
@item -gdwarf+
+@opindex gdwarf+
Produce debugging information in DWARF version 1 format (if that is
supported), using GNU extensions understood only by the GNU debugger
(GDB). The use of these extensions is likely to make other debuggers
crash or refuse to read the program.
@item -gdwarf-2
+@opindex gdwarf-2
Produce debugging information in DWARF version 2 format (if that is
supported). This is the format used by DBX on IRIX 6.
@cindex @code{prof}
@item -p
+@opindex p
Generate extra code to write profile information suitable for the
analysis program @code{prof}. You must use this option when compiling
the source files you want data about, and you must also use it when
@cindex @code{gprof}
@item -pg
+@opindex pg
Generate extra code to write profile information suitable for the
analysis program @code{gprof}. You must use this option when compiling
the source files you want data about, and you must also use it when
@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 @samp{-g} is
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
print some statistics about each pass when it finishes.
@item -ftime-report
+@opindex ftime-report
Makes the compiler print some statistics about the time consumed by each
pass when it finishes.
@item -fmem-report
+@opindex fmem-report
Makes the compiler print some statistics about permanent memory
allocation when it finishes.
@item -ax
+@opindex ax
Generate extra code to profile basic blocks. Your executable will
produce output that is a superset of that produced when @samp{-a} is
used. Additional output is the source and target address of the basic
frequencies.
@item -fprofile-arcs
+@opindex fprofile-arcs
Instrument @dfn{arcs} during compilation. For each function of your
program, GCC creates a program flow graph, then finds a spanning tree
for the graph. Only arcs that are not on the spanning tree have to be
@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:
@end table
@item -d@var{letters}
+@opindex d
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
@table @samp
@item A
+@opindex dA
Annotate the assembler output with miscellaneous debugging information.
@item b
+@opindex db
Dump after computing branch probabilities, to @file{@var{file}.11.bp}.
@item B
+@opindex dB
Dump after block reordering, to @file{@var{file}.26.bbro}.
@item c
+@opindex dc
Dump after instruction combination, to the file @file{@var{file}.14.combine}.
@item C
+@opindex dC
Dump after the first if conversion, to the file @file{@var{file}.15.ce}.
@item d
+@opindex dd
Dump after delayed branch scheduling, to @file{@var{file}.29.dbr}.
@item D
+@opindex dD
Dump all macro definitions, at the end of preprocessing, in addition to
normal output.
@item e
+@opindex de
Dump after SSA optimizations, to @file{@var{file}.05.ssa} and
@file{@var{file}.06.ussa}.
@item E
+@opindex dE
Dump after the second if conversion, to @file{@var{file}.24.ce2}.
@item f
+@opindex df
Dump after life analysis, to @file{@var{file}.13.life}.
@item F
+@opindex dF
Dump after purging @code{ADDRESSOF} codes, to @file{@var{file}.04.addressof}.
@item g
+@opindex dg
Dump after global register allocation, to @file{@var{file}.19.greg}.
@item o
+@opindex do
Dump after post-reload CSE and other optimizations, to @file{@var{file}.20.postreload}.
@item G
+@opindex dG
Dump after GCSE, to @file{@var{file}.08.gcse}.
@item i
+@opindex di
Dump after sibling call optimizations, to @file{@var{file}.01.sibling}.
@item j
+@opindex dj
Dump after the first jump optimization, to @file{@var{file}.02.jump}.
@item J
+@opindex dJ
Dump after the last jump optimization, to @file{@var{file}.27.jump2}.
@item k
+@opindex dk
Dump after conversion from registers to stack, to @file{@var{file}.29.stack}.
@item l
+@opindex dl
Dump after local register allocation, to @file{@var{file}.18.lreg}.
@item L
+@opindex dL
Dump after loop optimization, to @file{@var{file}.09.loop}.
@item M
+@opindex dM
Dump after performing the machine dependent reorganisation pass, to
@file{@var{file}.28.mach}.
@item n
+@opindex dn
Dump after register renumbering, to @file{@var{file}.23.rnreg}.
@item N
+@opindex dN
Dump after the register move pass, to @file{@var{file}.16.regmove}.
@item r
+@opindex dr
Dump after RTL generation, to @file{@var{file}.00.rtl}.
@item R
+@opindex dR
Dump after the second instruction scheduling pass, to
@file{@var{file}.25.sched2}.
@item s
+@opindex ds
Dump after CSE (including the jump optimization that sometimes follows
CSE), to @file{@var{file}.03.cse}.
@item S
+@opindex dS
Dump after the first instruction scheduling pass, to
@file{@var{file}.17.sched}.
@item t
+@opindex dt
Dump after the second CSE pass (including the jump optimization that
sometimes follows CSE), to @file{@var{file}.10.cse2}.
@item w
+@opindex dw
Dump after the second flow pass, to @file{@var{file}.21.flow2}.
@item X
+@opindex dX
Dump after dead code elimination, to @file{@var{file}.06.dce}.
@item z
+@opindex dz
Dump after the peephole pass, to @file{@var{file}.22.peephole2}.
@item a
+@opindex da
Produce all the dumps listed above.
@item m
+@opindex dm
Print statistics on memory usage, at the end of the run, to
standard error.
@item p
+@opindex dp
Annotate the assembler output with a comment indicating which
pattern and alternative was used. The length of each instruction is
also printed.
@item P
+@opindex dP
Dump the RTL in the assembler output as a comment before each instruction.
Also turns on @samp{-dp} annotation.
@item v
+@opindex dv
For each of the other indicated dump files (except for
@file{@var{file}.00.rtl}), dump a representation of the control flow graph
suitable for viewing with VCG to @file{@var{file}.@var{pass}.vcg}.
@item x
+@opindex dx
Just generate RTL for a function instead of compiling it. Usually used
with @samp{r}.
@item y
+@opindex dy
Dump debugging information during parsing, to standard error.
@end table
@item -fdump-unnumbered
+@opindex fdump-unnumbered
When doing debugging dumps (see -d option above), suppress instruction
numbers and line number note output. This makes it more feasible to
use diff on debugging dumps for compiler invocations with different
@item -fdump-translation-unit (C and C++ only)
@item -fdump-translation-unit-@var{number} (C and C++ only)
+@opindex fdump-translation-unit
Dump a representation of the tree structure for the entire translation
unit to a file. The file name is made by appending @file{.tu} to the
source file name. If the -@var{number} form is used, @var{number}
@item -fdump-class-hierarchy (C++ only)
@item -fdump-class-hierarchy-@var{number} (C++ only)
+@opindex fdump-class-hierarchy
Dump a representation of each class's hierarchy and virtual function
table layout to a file. The file name is made by appending @file{.class}
to the source file name. If the -@var{number} form is used, @var{number}
@item -fdump-ast-@var{switch} (C++ only)
@item -fdump-ast-@var{switch}-@var{number} (C++ only)
+@opindex fdump-ast
Control the dumping at various stages of processing the abstract syntax
tree to a file. The file name is generated by appending a switch
specific suffix to the source file name. If the -@var{number} form is
@end table
@item -fpretend-float
+@opindex fpretend-float
When running a cross-compiler, pretend that the target machine uses the
same floating point format as the host machine. This causes incorrect
output of the actual floating constants, but the actual instruction
the target machine.
@item -save-temps
+@opindex save-temps
Store the usual ``temporary'' intermediate files permanently; place them
in the current directory and name them based on the source file. Thus,
compiling @file{foo.c} with @samp{-c -save-temps} would produce files
normally uses an integrated preprocessor.
@item -time
+@opindex time
Report the CPU time taken by each subprocess in the compilation
sequence. For C source files, this is the compiler proper and assembler
(plus the linker if linking is done). The output looks like this:
Both numbers are in seconds.
@item -print-file-name=@var{library}
+@opindex print-file-name
Print the full absolute name of the library file @var{library} that
would be used when linking---and don't do anything else. With this
option, GCC does not compile or link anything; it just prints the
file name.
@item -print-prog-name=@var{program}
+@opindex print-prog-name
Like @samp{-print-file-name}, but searches for a program such as @samp{cpp}.
@item -print-libgcc-file-name
+@opindex print-libgcc-file-name
Same as @samp{-print-file-name=libgcc.a}.
This is useful when you use @samp{-nostdlib} or @samp{-nodefaultlibs}
@end example
@item -print-search-dirs
+@opindex print-search-dirs
Print the name of the configured installation directory and a list of
program and library directories gcc will search---and don't do anything else.
@xref{Environment Variables}.
@item -dumpmachine
+@opindex dumpmachine
Print the compiler's target machine (for example,
@samp{i686-pc-linux-gnu})---and don't do anything else.
@item -dumpversion
+@opindex dumpversion
Print the compiler version (for example, @samp{3.0})---and don't do
anything else.
@item -dumpspecs
+@opindex dumpspecs
Print the compiler's built-in specs---and don't do anything else. (This
is used when GCC itself is being built.) @xref{Spec Files}.
@end table
@table @gcctabopt
@item -O
@itemx -O1
+@opindex O
+@opindex O1
Optimize. Optimizing compilation takes somewhat more time, and a lot
more memory for a large function.
on other flags.@refill
@item -O2
+@opindex O2
Optimize even more. GCC performs nearly all supported optimizations
that do not involve a space-speed tradeoff. The compiler does not
perform loop unrolling or function inlining when you specify @samp{-O2}.
on machines where doing so does not interfere with debugging.
@item -O3
+@opindex O3
Optimize yet more. @samp{-O3} turns on all optimizations specified by
@samp{-O2} and also turns on the @samp{-finline-functions} and
@samp{-frename-registers} options.
@item -O0
+@opindex O0
Do not optimize.
@item -Os
+@opindex Os
Optimize for size. @samp{-Os} enables all @samp{-O2} optimizations that
do not typically increase code size. It also performs further
optimizations designed to reduce code size.
@table @gcctabopt
@item -ffloat-store
+@opindex ffloat-store
Do not store floating point variables in registers, and inhibit other
options that might change whether a floating point value is taken from a
register or memory.
them to store all pertinent intermediate computations into variables.
@item -fno-default-inline
+@opindex fno-default-inline
Do not make member functions inline by default merely because they are
defined inside the class scope (C++ only). Otherwise, when you specify
@w{@samp{-O}}, member functions defined inside class scope are compiled
the member function name.
@item -fno-defer-pop
+@opindex fno-defer-pop
Always pop the arguments to each function call as soon as that function
returns. For machines which must pop arguments after a function call,
the compiler normally lets arguments accumulate on the stack for several
function calls and pops them all at once.
@item -fforce-mem
+@opindex fforce-mem
Force memory operands to be copied into registers before doing
arithmetic on them. This produces better code by making all memory
references potential common subexpressions. When they are not common
register-load. The @samp{-O2} option turns on this option.
@item -fforce-addr
+@opindex fforce-addr
Force memory address constants to be copied into registers before
doing arithmetic on them. This may produce better code just as
@samp{-fforce-mem} may.
@item -fomit-frame-pointer
+@opindex fomit-frame-pointer
Don't keep the frame pointer in a register for functions that
don't need one. This avoids the instructions to save, set up and
restore frame pointers; it also makes an extra register available
@end ifclear
@item -foptimize-sibling-calls
+@opindex foptimize-sibling-calls
Optimize sibling and tail recursive calls.
@item -ftrapv
+@opindex ftrapv
This option generates traps for signed overflow on addition, subtraction,
multiplication operations.
@item -fno-inline
+@opindex fno-inline
Don't pay attention to the @code{inline} keyword. Normally this option
is used to keep the compiler from expanding any functions inline.
Note that if you are not optimizing, no functions can be expanded inline.
@item -finline-functions
+@opindex finline-functions
Integrate all simple functions into their callers. The compiler
heuristically decides which functions are simple enough to be worth
integrating in this way.
assembler code in its own right.
@item -finline-limit=@var{n}
+@opindex finline-limit
By default, gcc limits the size of functions that can be inlined. This flag
allows the control of this limit for functions that are explicitly marked as
inline (ie marked with the inline keyword or defined within the class
release to an another.
@item -fkeep-inline-functions
+@opindex fkeep-inline-functions
Even if all calls to a given function are integrated, and the function
is declared @code{static}, nevertheless output a separate run-time
callable version of the function. This switch does not affect
@code{extern inline} functions.
@item -fkeep-static-consts
+@opindex fkeep-static-consts
Emit variables declared @code{static const} when optimization isn't turned
on, even if the variables aren't referenced.
optimization is turned on, use the @samp{-fno-keep-static-consts} option.
@item -fno-function-cse
+@opindex fno-function-cse
Do not put function addresses in registers; make each instruction that
calls a constant function contain the function's address explicitly.
performed when this option is not used.
@item -ffast-math
+@opindex ffast-math
Sets @samp{-fno-math-errno}, @samp{-funsafe-math-optimizations},
and @samp{-fno-trapping-math}.
math functions.
@item -fno-math-errno
+@opindex fno-math-errno
Do not set ERRNO after calling math functions that are executed
with a single instruction, e.g., sqrt. A program that relies on
IEEE exceptions for math error handling may want to use this flag
sets @samp{-fno-math-errno}.
@item -funsafe-math-optimizations
+@opindex funsafe-math-optimizations
Allow optimizations for floating-point arithmetic that (a) assume
that arguments and results are valid and (b) may violate IEEE or
ANSI standards.
@samp{-ffast-math} option sets @samp{-funsafe-math-optimizations}.
@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.
@table @gcctabopt
@item -fstrength-reduce
+@opindex fstrength-reduce
Perform the optimizations of loop strength reduction and
elimination of iteration variables.
@item -fthread-jumps
+@opindex fthread-jumps
Perform optimizations where we check to see if a jump branches to a
location where another comparison subsumed by the first is found. If
so, the first branch is redirected to either the destination of the
the condition is known to be true or false.
@item -fcse-follow-jumps
+@opindex fcse-follow-jumps
In common subexpression elimination, scan through jump instructions
when the target of the jump is not reached by any other path. For
example, when CSE encounters an @code{if} statement with an
tested is false.
@item -fcse-skip-blocks
+@opindex fcse-skip-blocks
This is similar to @samp{-fcse-follow-jumps}, but causes CSE to
follow jumps which conditionally skip over blocks. When CSE
encounters a simple @code{if} statement with no else clause,
body of the @code{if}.
@item -frerun-cse-after-loop
+@opindex frerun-cse-after-loop
Re-run common subexpression elimination after loop optimizations has been
performed.
@item -frerun-loop-opt
+@opindex frerun-loop-opt
Run the loop optimizer twice.
@item -fgcse
+@opindex fgcse
Perform a global common subexpression elimination pass.
This pass also performs global constant and copy propagation.
@item -fgcse-lm
+@opindex fgcse-lm
When -fgcse-lm is enabled, global common subexpression elimination will
attempt to move loads which are only killed by stores into themselves. This
allows a loop containing a load/store sequence to be changed to a load outside
the loop, and a copy/store within the loop.
@item -fgcse-sm
+@opindex fgcse-sm
When -fgcse-sm is enabled, A store motion pass is run after global common
subexpression elimination. This pass will attempt to move stores out of loops.
When used in conjunction with -fgcse-lm, loops containing a load/store sequence
can be changed to a load before the loop and a store after the loop.
@item -fdelete-null-pointer-checks
+@opindex fdelete-null-pointer-checks
Use global dataflow analysis to identify and eliminate useless null
pointer checks. Programs which rely on NULL pointer dereferences @emph{not}
halting the program may not work properly with this option. Use
which depend on that behavior.
@item -fexpensive-optimizations
+@opindex fexpensive-optimizations
Perform a number of minor optimizations that are relatively expensive.
@item -foptimize-register-move
@itemx -fregmove
+@opindex foptimize-register-move
+@opindex fregmove
Attempt to reassign register numbers in move instructions and as
operands of other simple instructions in order to maximize the amount of
register tying. This is especially helpful on machines with two-operand
optimization.
@item -fdelayed-branch
+@opindex fdelayed-branch
If supported for the target machine, attempt to reorder instructions
to exploit instruction slots available after delayed branch
instructions.
@item -fschedule-insns
+@opindex fschedule-insns
If supported for the target machine, attempt to reorder instructions to
eliminate execution stalls due to required data being unavailable. This
helps machines that have slow floating point or memory load instructions
or floating point instruction is required.
@item -fschedule-insns2
+@opindex fschedule-insns2
Similar to @samp{-fschedule-insns}, but requests an additional pass of
instruction scheduling after register allocation has been done. This is
especially useful on machines with a relatively small number of
@item -ffunction-sections
@itemx -fdata-sections
+@opindex ffunction-sections
+@opindex fdata-sections
Place each function or data item into its own section in the output
file if the target supports arbitrary sections. The name of the
function or the name of the data item determines the section's name
you specify both this option and @samp{-g}.
@item -fcaller-saves
+@opindex fcaller-saves
Enable values to be allocated in registers that will be clobbered by
function calls, by emitting extra instructions to save and restore the
registers around such calls. Such allocation is done only when it
default.
@item -funroll-loops
+@opindex funroll-loops
Perform the optimization of loop unrolling. This is only done for loops
whose number of iterations can be determined at compile time or run time.
@samp{-funroll-loops} implies both @samp{-fstrength-reduce} and
@samp{-frerun-cse-after-loop}.
@item -funroll-all-loops
+@opindex funroll-all-loops
Perform the optimization of loop unrolling. This is done for all loops
and usually makes programs run more slowly. @samp{-funroll-all-loops}
implies @samp{-fstrength-reduce} as well as @samp{-frerun-cse-after-loop}.
@item -fmove-all-movables
+@opindex fmove-all-movables
Forces all invariant computations in loops to be moved
outside the loop.
@item -freduce-all-givs
+@opindex freduce-all-givs
Forces all general-induction variables in loops to be
strength-reduced.
when these options are @emph{enabled}.
@item -fno-peephole
+@opindex fno-peephole
Disable any machine-specific peephole optimizations.
@item -fbranch-probabilities
+@opindex fbranch-probabilities
After running a program compiled with @samp{-fprofile-arcs}
(@pxref{Debugging Options,, Options for Debugging Your Program or
@command{gcc}}), you can compile it a second time using
@end ifset
@item -fno-guess-branch-probability
+@opindex fno-guess-branch-probability
Sometimes gcc will opt to guess branch probabilities when none are
available from either profile directed feedback (@samp{-fprofile-arcs})
or @samp{__builtin_expect}. In a hard real-time system, people don't
of inferior optimization.
@item -fstrict-aliasing
+@opindex fstrict-aliasing
Allows the compiler to assume the strictest aliasing rules applicable to
the language being compiled. For C (and C++), this activates
optimizations based on the type of expressions. In particular, an
@item -falign-functions
@itemx -falign-functions=@var{n}
+@opindex falign-functions
Align the start of functions to the next power-of-two greater than
@var{n}, skipping up to @var{n} bytes. For instance,
@samp{-falign-functions=32} aligns functions to the next 32-byte
@item -falign-labels
@itemx -falign-labels=@var{n}
+@opindex falign-labels
Align all branch targets to a power-of-two boundary, skipping up to
@var{n} bytes like @samp{-falign-functions}. This option can easily
make code slower, because it must insert dummy operations for when the
@item -falign-loops
@itemx -falign-loops=@var{n}
+@opindex falign-loops
Align loops to a power-of-two boundary, skipping up to @var{n} bytes
like @samp{-falign-functions}. The hope is that the loop will be
executed many times, which will make up for any execution of the dummy
@item -falign-jumps
@itemx -falign-jumps=@var{n}
+@opindex falign-jumps
Align branch targets to a power-of-two boundary, for branch targets
where the targets can only be reached by jumping, skipping up to @var{n}
bytes like @samp{-falign-functions}. In this case, no dummy operations
If @var{n} is not specified, use a machine-dependent default.
@item -fssa
+@opindex fssa
Perform optimizations in static single assignment form. Each function's
flow graph is translated into SSA form, optimizations are performed, and
the flow graph is translated back from SSA form. Users should not
specify this option, since it is not yet ready for production use.
@item -fdce
+@opindex fdce
Perform dead-code elimination in SSA form. Requires @samp{-fssa}. Like
@samp{-fssa}, this is an experimental feature.
@item -fsingle-precision-constant
+@opindex fsingle-precision-constant
Treat floating point constant as single precision constant instead of
implicitly converting it to double precision constant.
@item -frename-registers
+@opindex frename-registers
Attempt to avoid false dependancies in scheduled code by making use
of registers left over after register allocation. This optimization
will most benefit processors with lots of registers. It can, however,
a ``home register''.
@item --param @var{name}=@var{value}
+@opindex param
In some places, GCC uses various constants to control the amount of
optimization that is done. For example, GCC will not inline functions
that contain more that a certain number of instructions. You can
@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 @samp{-D}
and @samp{-U} options on the command line are always processed before
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 @samp{-imacros @var{file}}
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
@samp{-I} adds to).
@item -iprefix @var{prefix}
+@opindex iprefix
Specify @var{prefix} as the prefix for subsequent @samp{-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 @samp{-iprefix}. If you have not specified a
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
@samp{-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 @samp{-I} options (and the
current directory, if appropriate) are searched. @xref{Directory
search path to only those directories you specify explicitly.
@item -remap
-@findex -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.
token is the actual name to use.
@item -undef
+@opindex undef
Do not predefine any nonstandard macros. (Including architecture flags).
@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 -C
+@opindex C
Tell the preprocessor not to discard comments. Used with the
@samp{-E} option.
@item -P
+@opindex P
Tell the preprocessor not to generate @samp{#line} directives.
Used with the @samp{-E} option.
@cindex make
@cindex dependencies, make
@item -M
-@findex -M
+@opindex M
Instead of outputting the result of preprocessing, output a rule
suitable for @code{make} describing the dependencies of the main source
file. The preprocessor outputs one @code{make} rule containing the
@samp{-M} implies @samp{-E}.
@item -MM
-@findex -MM
+@opindex MM
Like @samp{-M}, but mention only the files included with @samp{#include
"@var{file}"}. System header files included with @samp{#include
<@var{file}>} are omitted.
@item -MD
-@findex -MD
+@opindex MD
Like @samp{-M} but the dependency information is written to a file
rather than stdout. @code{gcc} will use the same file name and
directory as the object file, but with the suffix ".d" instead.
the @samp{make} command.
@item -MMD
-@findex -MMD
+@opindex MMD
Like @samp{-MD} except mention only user header files, not system
-header files.
@item -MF @var{file}
-@findex -MF
+@opindex MF
When used with @samp{-M} or @samp{-MM}, specifies a file to write the
dependencies to. This allows the preprocessor to write the preprocessed
file to stdout normally. If no @samp{-MF} switch is given, CPP sends
Variables}).
@item -MG
-@findex -MG
+@opindex MG
When used with @samp{-M} or @samp{-MM}, @samp{-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
This feature is used in automatic updating of makefiles.
@item -MP
-@findex -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
@item -MQ @var{target}
@item -MT @var{target}
-@findex -MQ
-@findex -MT
+@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 @samp{-MT} you can specify a
@samp{-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})}. @samp{-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}
order in which they are written.
@item -U@var{macro}
+@opindex U
Undefine macro @var{macro}. @samp{-U} options are evaluated after all
@samp{-D} options, but before any @samp{-include} and @samp{-imacros}
options.
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 @samp{-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 @samp{-dD} except that the macro arguments and contents are omitted.
Only @samp{#define @var{name}} is included in the output.
@item -dI
-@findex -dI
+@opindex dI
Output @samp{#include} directives in addition to the result of
preprocessing.
@item -trigraphs
-@findex -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
converted or ignored.
@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
@table @gcctabopt
@item -Wa\,@var{option}
+@opindex Wa
Pass @var{option} as an option to the assembler. If @var{option}
contains commas, it is split into multiple options at the commas.
@end table
@item -c
@itemx -S
@itemx -E
+@opindex c
+@opindex S
+@opindex E
If any of these options is used, then the linker is not run, and
object file names should not be used as arguments. @xref{Overall
Options}.
@cindex Libraries
@item -l@var{library}
@itemx -l @var{library}
+@opindex l
Search the library named @var{library} when linking. (The second
alternative with the library as a separate argument is only for
POSIX compliance and is not recommended.)
and searches several directories.
@item -lobjc
+@opindex lobjc
You need this special case of the @samp{-l} option in order to
link an Objective C program.
@item -nostartfiles
+@opindex nostartfiles
Do not use the standard system startup files when linking.
The standard system libraries are used normally, unless @option{-nostdlib}
or @option{-nodefaultlibs} is used.
@item -nodefaultlibs
+@opindex nodefaultlibs
Do not use the standard system libraries when linking.
Only the libraries you specify will be passed to the linker.
The standard startup files are used normally, unless @option{-nostartfiles}
mechanism when this option is specified.
@item -nostdlib
+@opindex nostdlib
Do not use the standard system startup files or libraries when linking.
No startup files and only the libraries you specify will be passed to
the linker. The compiler may generate calls to memcmp, memset, and memcpy
constructors will be called; @pxref{Collect2,,@command{collect2}}.)
@item -s
+@opindex s
Remove all symbol table and relocation information from the executable.
@item -static
+@opindex static
On systems that support dynamic linking, this prevents linking with the shared
libraries. On other systems, this option has no effect.
@item -shared
+@opindex shared
Produce a shared object which can then be linked with other objects to
form an executable. Not all systems support this option. For predictable
results, you must also specify the same set of options that were used to
@item -shared-libgcc
@itemx -static-libgcc
+@opindex shared-libgcc
+@opindex static-libgcc
On systems that provide @file{libgcc} as a shared library, these options
force the use of either the shared or static version respectively.
If no shared version of @file{libgcc} was built when the compiler was
@file{libgcc}.
@item -symbolic
+@opindex symbolic
Bind references to global symbols when building a shared object. Warn
about any unresolved references (unless overridden by the link editor
option @samp{-Xlinker -z -Xlinker defs}). Only a few systems support
this option.
@item -Xlinker @var{option}
+@opindex Xlinker
Pass @var{option} as an option to the linker. You can use this to
supply system-specific linker options which GCC does not know how to
recognize.
string as a single argument, which is not what the linker expects.
@item -Wl\,@var{option}
+@opindex Wl
Pass @var{option} as an option to the linker. If @var{option} contains
commas, it is split into multiple options at the commas.
@item -u @var{symbol}
+@opindex u
Pretend the symbol @var{symbol} is undefined, to force linking of
library modules to define it. You can use @samp{-u} multiple times with
different symbols to force loading of additional library modules.
@table @gcctabopt
@item -I@var{dir}
+@opindex I
Add the directory @var{dir} to the head of the list of directories to be
searched for header files. This can be used to override a system header
file, substituting your own version, since these directories are
order; the standard system directories come after.
@item -I-
+@opindex I-
Any directories you specify with @samp{-I} options before the @samp{-I-}
option are searched only for the case of @samp{#include "@var{file}"};
they are not searched for @samp{#include <@var{file}>}.
independent.
@item -L@var{dir}
+@opindex L
Add directory @var{dir} to the list of directories to be searched
for @samp{-l}.
@item -B@var{prefix}
+@opindex B
This option specifies where to find the executables, libraries,
include files, and data files of the compiler itself.
Variables}.
@item -specs=@var{file}
+@opindex specs
Process @var{file} after the compiler reads in the standard @file{specs}
file, in order to override the defaults that the @file{gcc} driver
program uses when determining what switches to pass to @file{cc1},
@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 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.
@table @gcctabopt
@item -m68000
@itemx -mc68000
+@opindex m68000
+@opindex mc68000
Generate output for a 68000. This is the default
when the compiler is configured for 68000-based systems.
@item -m68020
@itemx -mc68020
+@opindex m68020
+@opindex mc68020
Generate output for a 68020. This is the default
when the compiler is configured for 68020-based systems.
@item -m68881
+@opindex m68881
Generate output containing 68881 instructions for floating point.
This is the default for most 68020 systems unless @samp{-nfp} was
specified when the compiler was configured.
@item -m68030
+@opindex m68030
Generate output for a 68030. This is the default when the compiler is
configured for 68030-based systems.
@item -m68040
+@opindex m68040
Generate output for a 68040. This is the default when the compiler is
configured for 68040-based systems.
have code to emulate those instructions.
@item -m68060
+@opindex m68060
Generate output for a 68060. This is the default when the compiler is
configured for 68060-based systems.
does not have code to emulate those instructions.
@item -mcpu32
+@opindex mcpu32
Generate output for a CPU32. This is the default
when the compiler is configured for CPU32-based systems.
68336, 68340, 68341, 68349 and 68360.
@item -m5200
+@opindex m5200
Generate output for a 520X "coldfire" family cpu. This is the default
when the compiler is configured for 520X-based systems.
@item -m68020-40
+@opindex m68020-40
Generate output for a 68040, without using any of the new instructions.
This results in code which can run relatively efficiently on either a
68020/68881 or a 68030 or a 68040. The generated code does use the
68881 instructions that are emulated on the 68040.
@item -m68020-60
+@opindex m68020-60
Generate output for a 68060, without using any of the new instructions.
This results in code which can run relatively efficiently on either a
68020/68881 or a 68030 or a 68040. The generated code does use the
68881 instructions that are emulated on the 68060.
@item -mfpa
+@opindex mfpa
Generate output containing Sun FPA instructions for floating point.
@item -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not available for all m68k
targets. Normally the facilities of the machine's usual C compiler are
@samp{m68k-*-coff} do provide software floating point support.
@item -mshort
+@opindex mshort
Consider type @code{int} to be 16 bits wide, like @code{short int}.
@item -mnobitfield
+@opindex mnobitfield
Do not use the bit-field instructions. The @samp{-m68000}, @samp{-mcpu32}
and @samp{-m5200} options imply @w{@samp{-mnobitfield}}.
@item -mbitfield
+@opindex mbitfield
Do use the bit-field instructions. The @samp{-m68020} option implies
@samp{-mbitfield}. This is the default if you use a configuration
designed for a 68020.
@item -mrtd
+@opindex mrtd
Use a different function-calling convention, in which functions
that take a fixed number of arguments return with the @code{rtd}
instruction, which pops their arguments while returning. This
@item -malign-int
@itemx -mno-align-int
+@opindex malign-int
+@opindex mno-align-int
Control whether GCC aligns @code{int}, @code{long}, @code{long long},
@code{float}, @code{double}, and @code{long double} variables on a 32-bit
boundary (@samp{-malign-int}) or a 16-bit boundary (@samp{-mno-align-int}).
most published application binary interface specifications for the m68k.
@item -mpcrel
+@opindex mpcrel
Use the pc-relative addressing mode of the 68000 directly, instead of
using a global offset table. At present, this option implies -fpic,
allowing at most a 16-bit offset for pc-relative addressing. -fPIC is
@item -mno-strict-align
@itemx -mstrict-align
-@kindex -mstrict-align
+@opindex mno-strict-align
+@opindex mstrict-align
Do not (do) assume that unaligned memory references will be handled by
the system.
@table @gcctabopt
@item -m6811
@itemx -m68hc11
+@opindex m6811
+@opindex m68hc11
Generate output for a 68HC11. This is the default
when the compiler is configured for 68HC11-based systems.
@item -m6812
@itemx -m68hc12
+@opindex m6812
+@opindex m68hc12
Generate output for a 68HC12. This is the default
when the compiler is configured for 68HC12-based systems.
@item -mauto-incdec
+@opindex mauto-incdec
Enable the use of 68HC12 pre and post auto-increment and auto-decrement
addressing modes.
@item -mshort
+@opindex mshort
Consider type @code{int} to be 16 bits wide, like @code{short int}.
@item -msoft-reg-count=@var{count}
+@opindex msoft-reg-count
Specify the number of pseudo-soft registers which are used for the
code generation. The maximum number is 32. Using more pseudo-soft
register may or may not result in better code depending on the program.
@table @gcctabopt
@item -munix
+@opindex munix
Do not output certain jump instructions (@code{aobleq} and so on)
that the Unix assembler for the Vax cannot handle across long
ranges.
@item -mgnu
+@opindex mgnu
Do output those jump instructions, on the assumption that you
will assemble with the GNU assembler.
@item -mg
+@opindex mg
Output code for g-format floating point numbers instead of d-format.
@end table
@table @gcctabopt
@item -mno-app-regs
@itemx -mapp-regs
+@opindex mno-app-regs
+@opindex mapp-regs
Specify @samp{-mapp-regs} to generate output using the global registers
2 through 4, which the SPARC SVR4 ABI reserves for applications. This
is the default.
@item -mfpu
@itemx -mhard-float
+@opindex mfpu
+@opindex mhard-float
Generate output containing floating point instructions. This is the
default.
@item -mno-fpu
@itemx -msoft-float
+@opindex mno-fpu
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not available for all SPARC
targets. Normally the facilities of the machine's usual C compiler are
this to work.
@item -mhard-quad-float
+@opindex mhard-quad-float
Generate output containing quad-word (long double) floating point
instructions.
@item -msoft-quad-float
+@opindex msoft-quad-float
Generate output containing library calls for quad-word (long double)
floating point instructions. The functions called are those specified
in the SPARC ABI. This is the default.
@item -mno-epilogue
@itemx -mepilogue
+@opindex mno-epilogue
+@opindex mepilogue
With @samp{-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
@item -mno-flat
@itemx -mflat
+@opindex mno-flat
+@opindex mflat
With @samp{-mflat}, the compiler does not generate save/restore instructions
and will use a "flat" or single register window calling convention.
This model uses %i7 as the frame pointer and is compatible with the normal
@item -mno-unaligned-doubles
@itemx -munaligned-doubles
+@opindex mno-unaligned-doubles
+@opindex munaligned-doubles
Assume that doubles have 8 byte alignment. This is the default.
With @samp{-munaligned-doubles}, GCC assumes that doubles have 8 byte
@item -mno-faster-structs
@itemx -mfaster-structs
+@opindex mno-faster-structs
+@opindex mfaster-structs
With @samp{-mfaster-structs}, the compiler assumes that structures
should have 8 byte alignment. This enables the use of pairs of
@code{ldd} and @code{std} instructions for copies in structure
@item -mv8
@itemx -msparclite
+@opindex mv8
+@opindex msparclite
These two options select variations on the SPARC architecture.
By default (unless specifically configured for the Fujitsu SPARClite),
@item -mcypress
@itemx -msupersparc
+@opindex mcypress
+@opindex msupersparc
These two options select the processor for which the code is optimised.
With @samp{-mcypress} (the default), the compiler optimizes code for the
They have been replaced with @samp{-mcpu=xxx}.
@item -mcpu=@var{cpu_type}
+@opindex mcpu
Set the instruction set, register set, and instruction scheduling parameters
for machine type @var{cpu_type}. Supported values for @var{cpu_type} are
@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{sparclite},
@end smallexample
@item -mtune=@var{cpu_type}
+@opindex mtune
Set the instruction scheduling parameters for machine type
@var{cpu_type}, but do not set the instruction set or register set that the
option @samp{-mcpu=}@var{cpu_type} would.
@table @gcctabopt
@item -mlittle-endian
+@opindex mlittle-endian
Generate code for a processor running in little-endian mode.
@item -mlive-g0
+@opindex mlive-g0
Treat register @code{%g0} as a normal register.
GCC will continue to clobber it as necessary but will not assume
it always reads as 0.
@item -mbroken-saverestore
+@opindex mbroken-saverestore
Generate code that does not use non-trivial forms of the @code{save} and
@code{restore} instructions. Early versions of the SPARCLET processor do
not correctly handle @code{save} and @code{restore} instructions used with
@table @gcctabopt
@item -mlittle-endian
+@opindex mlittle-endian
Generate code for a processor running in little-endian mode.
@item -m32
@itemx -m64
+@opindex m32
+@opindex m64
Generate code for a 32-bit or 64-bit environment.
The 32-bit environment sets int, long and pointer to 32 bits.
The 64-bit environment sets int to 32 bits and long and pointer
to 64 bits.
@item -mcmodel=medlow
+@opindex mcmodel=medlow
Generate code for the Medium/Low code model: the program must be linked
in the low 32 bits of the address space. Pointers are 64 bits.
Programs can be statically or dynamically linked.
@item -mcmodel=medmid
+@opindex mcmodel=medmid
Generate code for the Medium/Middle code model: the program must be linked
in the low 44 bits of the address space, the text segment must be less than
2G bytes, and data segment must be within 2G of the text segment.
Pointers are 64 bits.
@item -mcmodel=medany
+@opindex mcmodel=medany
Generate code for the Medium/Anywhere code model: the program may be linked
anywhere in the address space, the text segment must be less than
2G bytes, and data segment must be within 2G of the text segment.
Pointers are 64 bits.
@item -mcmodel=embmedany
+@opindex mcmodel=embmedany
Generate code for the Medium/Anywhere code model for embedded systems:
assume a 32-bit text and a 32-bit data segment, both starting anywhere
(determined at link time). Register %g4 points to the base of the
@item -mstack-bias
@itemx -mno-stack-bias
+@opindex mstack-bias
+@opindex mno-stack-bias
With @samp{-mstack-bias}, GCC assumes that the stack pointer, and
frame pointer if present, are offset by -2047 which must be added back
when making stack frame references.
@table @gcctabopt
@item -mc1
+@opindex mc1
Generate output for C1. The code will run on any Convex machine.
The preprocessor symbol @code{__convex__c1__} is defined.
@item -mc2
+@opindex mc2
Generate output for C2. Uses instructions not available on C1.
Scheduling and other optimizations are chosen for max performance on C2.
The preprocessor symbol @code{__convex_c2__} is defined.
@item -mc32
+@opindex mc32
Generate output for C32xx. Uses instructions not available on C1.
Scheduling and other optimizations are chosen for max performance on C32.
The preprocessor symbol @code{__convex_c32__} is defined.
@item -mc34
+@opindex mc34
Generate output for C34xx. Uses instructions not available on C1.
Scheduling and other optimizations are chosen for max performance on C34.
The preprocessor symbol @code{__convex_c34__} is defined.
@item -mc38
+@opindex mc38
Generate output for C38xx. Uses instructions not available on C1.
Scheduling and other optimizations are chosen for max performance on C38.
The preprocessor symbol @code{__convex_c38__} is defined.
@item -margcount
+@opindex margcount
Generate code which puts an argument count in the word preceding each
argument list. This is compatible with regular CC, and a few programs
may need the argument count word. GDB and other source-level debuggers
do not need it; this info is in the symbol table.
@item -mnoargcount
+@opindex mnoargcount
Omit the argument count word. This is the default.
@item -mvolatile-cache
+@opindex mvolatile-cache
Allow volatile references to be cached. This is the default.
@item -mvolatile-nocache
+@opindex mvolatile-nocache
Volatile references bypass the data cache, going all the way to memory.
This is only needed for multi-processor code that does not use standard
synchronization instructions. Making non-volatile references to volatile
locations will not necessarily work.
@item -mlong32
+@opindex mlong32
Type long is 32 bits, the same as type int. This is the default.
@item -mlong64
+@opindex mlong64
Type long is 64 bits, the same as type long long. This option is useless,
because no library support exists for it.
@end table
@table @gcctabopt
@item -mdw
-@kindex -mdw
+@opindex mdw
@cindex DW bit (29k)
Generate code that assumes the @code{DW} bit is set, i.e., that byte and
halfword operations are directly supported by the hardware. This is the
default.
@item -mndw
-@kindex -mndw
+@opindex mndw
Generate code that assumes the @code{DW} bit is not set.
@item -mbw
-@kindex -mbw
+@opindex mbw
@cindex byte writes (29k)
Generate code that assumes the system supports byte and halfword write
operations. This is the default.
@item -mnbw
-@kindex -mnbw
+@opindex mnbw
Generate code that assumes the systems does not support byte and
halfword write operations. @samp{-mnbw} implies @samp{-mndw}.
@item -msmall
-@kindex -msmall
+@opindex msmall
@cindex memory model (29k)
Use a small memory model that assumes that all function addresses are
either within a single 256 KB segment or at an absolute address of less
of a @code{const}, @code{consth}, @code{calli} sequence.
@item -mnormal
-@kindex -mnormal
+@opindex mnormal
Use the normal memory model: Generate @code{call} instructions only when
calling functions in the same file and @code{calli} instructions
otherwise. This works if each file occupies less than 256 KB but allows
the entire executable to be larger than 256 KB. This is the default.
@item -mlarge
+@opindex mlarge
Always use @code{calli} instructions. Specify this option if you expect
a single file to compile into more than 256 KB of code.
@item -m29050
-@kindex -m29050
+@opindex m29050
@cindex processor selection (29k)
Generate code for the Am29050.
@item -m29000
-@kindex -m29000
+@opindex m29000
Generate code for the Am29000. This is the default.
@item -mkernel-registers
-@kindex -mkernel-registers
+@opindex mkernel-registers
@cindex kernel and user registers (29k)
Generate references to registers @code{gr64-gr95} instead of to
registers @code{gr96-gr127}. This option can be used when compiling
must use the normal, user-mode, names.
@item -muser-registers
-@kindex -muser-registers
+@opindex muser-registers
Use the normal set of global registers, @code{gr96-gr127}. This is the
default.
@item -mstack-check
@itemx -mno-stack-check
-@kindex -mstack-check
+@opindex mstack-check
+@opindex mno-stack-check
@cindex stack checks (29k)
Insert (or do not insert) a call to @code{__msp_check} after each stack
adjustment. This is often used for kernel code.
@item -mstorem-bug
@itemx -mno-storem-bug
-@kindex -mstorem-bug
+@opindex mstorem-bug
+@opindex mno-storem-bug
@cindex storem bug (29k)
@samp{-mstorem-bug} handles 29k processors which cannot handle the
separation of a mtsrim insn and a storem instruction (most 29000 chips
@item -mno-reuse-arg-regs
@itemx -mreuse-arg-regs
-@kindex -mreuse-arg-regs
+@opindex mno-reuse-arg-regs
+@opindex mreuse-arg-regs
@samp{-mno-reuse-arg-regs} tells the compiler to only use incoming argument
registers for copying out arguments. This helps detect calling a function
with fewer arguments than it was declared with.
@item -mno-impure-text
@itemx -mimpure-text
-@kindex -mimpure-text
+@opindex mno-impure-text
+@opindex mimpure-text
@samp{-mimpure-text}, used in addition to @samp{-shared}, tells the compiler to
not pass @samp{-assert pure-text} to the linker when linking a shared object.
@item -msoft-float
-@kindex -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not part of GCC.
Normally the facilities of the machine's usual C compiler are used, but
cross-compilation.
@item -mno-multm
-@kindex -mno-multm
+@opindex mno-multm
Do not generate multm or multmu instructions. This is useful for some embedded
systems which do not have trap handlers for these instructions.
@end table
@table @gcctabopt
@item -mapcs-frame
-@kindex -mapcs-frame
+@opindex mapcs-frame
Generate a stack frame that is compliant with the ARM Procedure Call
Standard for all functions, even if this is not strictly necessary for
correct execution of the code. Specifying @samp{-fomit-frame-pointer}
leaf functions. The default is @samp{-mno-apcs-frame}.
@item -mapcs
-@kindex -mapcs
+@opindex mapcs
This is a synonym for @samp{-mapcs-frame}.
@item -mapcs-26
-@kindex -mapcs-26
+@opindex mapcs-26
Generate code for a processor running with a 26-bit program counter,
and conforming to the function calling standards for the APCS 26-bit
option. This option replaces the @samp{-m2} and @samp{-m3} options
of previous releases of the compiler.
@item -mapcs-32
-@kindex -mapcs-32
+@opindex mapcs-32
Generate code for a processor running with a 32-bit program counter,
and conforming to the function calling standards for the APCS 32-bit
option. This option replaces the @samp{-m6} option of previous releases
@ignore
@c not currently implemented
@item -mapcs-stack-check
-@kindex -mapcs-stack-check
-@kindex -mno-apcs-stack-check
+@opindex mapcs-stack-check
Generate code to check the amount of stack space available upon entry to
every function (that actually uses some stack space). If there is
insufficient space available then either the function
@c not currently implemented
@item -mapcs-float
-@kindex -mapcs-float
-@kindex -mno-apcs-float
+@opindex mapcs-float
Pass floating point arguments using the float point registers. This is
one of the variants of the APCS. This option is recommended if the
target hardware has a floating point unit or if a lot of floating point
@c not currently implemented
@item -mapcs-reentrant
-@kindex -mapcs-reentrant
-@kindex -mno-apcs-reentrant
+@opindex mapcs-reentrant
Generate reentrant, position independent code. The default is
@samp{-mno-apcs-reentrant}.
@end ignore
@item -mthumb-interwork
-@kindex -mthumb-interwork
-@kindex -mno-thumb-interwork
+@opindex mthumb-interwork
Generate code which supports calling between the ARM and Thumb
instruction sets. Without this option the two instruction sets cannot
be reliably used inside one program. The default is
when @samp{-mthumb-interwork} is specified.
@item -mno-sched-prolog
-@kindex -mno-sched-prolog
-@kindex -msched-prolog
+@opindex mno-sched-prolog
Prevent the reordering of instructions in the function prolog, or the
merging of those instruction with the instructions in the function's
body. This means that all functions will start with a recognizable set
default is @samp{-msched-prolog}.
@item -mhard-float
+@opindex mhard-float
Generate output containing floating point instructions. This is the
default.
@item -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not available for all ARM
targets. Normally the facilities of the machine's usual C compiler are
this to work.
@item -mlittle-endian
+@opindex mlittle-endian
Generate code for a processor running in little-endian mode. This is
the default for all standard configurations.
@item -mbig-endian
+@opindex mbig-endian
Generate code for a processor running in big-endian mode; the default is
to compile code for a little-endian processor.
@item -mwords-little-endian
+@opindex mwords-little-endian
This option only applies when generating code for big-endian processors.
Generate code for a little-endian word order but a big-endian byte
order. That is, a byte order of the form @samp{32107654}. Note: this
2.8.
@item -malignment-traps
-@kindex -malignment-traps
+@opindex malignment-traps
Generate code that will not trap if the MMU has alignment traps enabled.
On ARM architectures prior to ARMv4, there were no instructions to
access half-word objects stored in memory. However, when reading from
objects in memory.
@item -mno-alignment-traps
-@kindex -mno-alignment-traps
+@opindex mno-alignment-traps
Generate code that assumes that the MMU will not trap unaligned
accesses. This produces better code when the target instruction set
does not have half-word memory operations (i.e. implementations prior to
@item -mshort-load-bytes
@itemx -mno-short-load-words
-@kindex -mshort-load-bytes
-@kindex -mno-short-load-words
+@opindex mshort-load-bytes
+@opindex mno-short-load-words
These are deprecated aliases for @samp{-malignment-traps}.
@item -mno-short-load-bytes
@itemx -mshort-load-words
-@kindex -mno-short-load-bytes
-@kindex -mshort-load-words
+@opindex mno-short-load-bytes
+@opindex mshort-load-words
This are deprecated aliases for @samp{-mno-alignment-traps}.
@item -mbsd
-@kindex -mbsd
+@opindex mbsd
This option only applies to RISC iX. Emulate the native BSD-mode
compiler. This is the default if @samp{-ansi} is not specified.
@item -mxopen
-@kindex -mxopen
+@opindex mxopen
This option only applies to RISC iX. Emulate the native X/Open-mode
compiler.
@item -mno-symrename
-@kindex -mno-symrename
+@opindex mno-symrename
This option only applies to RISC iX. Do not run the assembler
post-processor, @samp{symrename}, after code has been assembled.
Normally it is necessary to modify some of the standard symbols in
suppresses this pass. The post-processor is never run when the
compiler is built for cross-compilation.
-@item -mcpu=<name>
-@kindex -mcpu=
+@item -mcpu=@var{name}
+@opindex mcpu
This specifies the name of the target ARM processor. GCC uses this name
to determine what kind of instructions it can emit when generating
assembly code. Permissible names are: arm2, arm250, arm3, arm6, arm60,
arm9, arm9e, arm920, arm920t, arm940t, arm9tdmi, arm10tdmi, arm1020t,
xscale.
-@itemx -mtune=<name>
-@kindex -mtune=
+@itemx -mtune=@var{name}
+@opindex mtune
This option is very similar to the @samp{-mcpu=} option, except that
instead of specifying the actual target processor type, and hence
restricting which instructions can be used, it specifies that GCC should
For some ARM implementations better performance can be obtained by using
this option.
-@item -march=<name>
-@kindex -march=
+@item -march=@var{name}
+@opindex march
This specifies the name of the target ARM architecture. GCC uses this
name to determine what kind of instructions it can emit when generating
assembly code. This option can be used in conjunction with or instead
of the @samp{-mcpu=} option. Permissible names are: armv2, armv2a,
armv3, armv3m, armv4, armv4t, armv5, armv5t, armv5te.
-@item -mfpe=<number>
-@itemx -mfp=<number>
-@kindex -mfpe=
-@kindex -mfp=
+@item -mfpe=@var{number}
+@itemx -mfp=@var{number}
+@opindex mfpe
+@opindex mfp
This specifies the version of the floating point emulation available on
the target. Permissible values are 2 and 3. @samp{-mfp=} is a synonym
for @samp{-mfpe=}, for compatibility with older versions of GCC.
-@item -mstructure-size-boundary=<n>
-@kindex -mstructure-size-boundary
+@item -mstructure-size-boundary=@var{n}
+@opindex mstructure-size-boundary
The size of all structures and unions will be rounded up to a multiple
of the number of bits set by this option. Permissible values are 8 and
32. The default value varies for different toolchains. For the COFF
using structures or unions.
@item -mabort-on-noreturn
-@kindex -mabort-on-noreturn
-@kindex -mnoabort-on-noreturn
+@opindex mabort-on-noreturn
Generate a call to the function @code{abort} at the end of a
@code{noreturn} function. It will be executed if the function tries to
return.
@item -mlong-calls
@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
Tells the compiler to perform function calls by first loading the
address of the function into a register and then performing a subroutine
call on this register. This switch is needed if the target function
pointers.
@item -mnop-fun-dllimport
-@kindex -mnop-fun-dllimport
+@opindex mnop-fun-dllimport
Disable support for the @emph{dllimport} attribute.
@item -msingle-pic-base
-@kindex -msingle-pic-base
+@opindex msingle-pic-base
Treat the register used for PIC addressing as read-only, rather than
loading it in the prologue for each function. The run-time system is
responsible for initialising this register with an appropriate value
before execution begins.
-@item -mpic-register=<reg>
-@kindex -mpic-register=
+@item -mpic-register=@var{reg}
+@opindex mpic-register
Specify the register to be used for PIC addressing. The default is R10
unless stack-checking is enabled, when R9 is used.
@item -mpoke-function-name
-@kindex -mpoke-function-name
+@opindex mpoke-function-name
Write the name of each function into the text section, directly
preceding the function prologue. The generated code is similar to this:
and has length @code{((pc[-3]) & 0xff000000)}.
@item -mthumb
-@kindex -mthumb
+@opindex mthumb
Generate code for the 16-bit Thumb instruction set. The default is to
use the 32-bit ARM instruction set.
@item -mtpcs-frame
-@kindex -mtpcs-frame
-@kindex -mno-tpcs-frame
+@opindex mtpcs-frame
Generate a stack frame that is compliant with the Thumb Procedure Call
Standard for all non-leaf functions. (A leaf function is one that does
not call any other functions.) The default is @samp{-mno-tpcs-frame}.
@item -mtpcs-leaf-frame
-@kindex -mtpcs-leaf-frame
-@kindex -mno-tpcs-leaf-frame
+@opindex mtpcs-leaf-frame
Generate a stack frame that is compliant with the Thumb Procedure Call
Standard for all leaf functions. (A leaf function is one that does
not call any other functions.) The default is @samp{-mno-apcs-leaf-frame}.
@item -mcallee-super-interworking
-@kindex -mcallee-super-interworking
+@opindex mcallee-super-interworking
Gives all externally visible functions in the file being compiled an ARM
instruction set header which switches to Thumb mode before executing the
rest of the function. This allows these functions to be called from
non-interworking code.
@item -mcaller-super-interworking
-@kindex -mcaller-super-interworking
+@opindex mcaller-super-interworking
Allows calls via function pointers (including virtual functions) to
execute correctly regardless of whether the target code has been
compiled for interworking or not. There is a small overhead in the cost
@table @gcctabopt
@item -mrelax
+@opindex mrelax
Indicate to the linker that it should perform a relaxation optimization pass
to shorten branches, calls and absolute memory addresses. This option only
has an effect when used on the command line for the final link step.
@table @gcctabopt
@item -mmult-bug
+@opindex mmult-bug
Generate code to avoid bugs in the multiply instructions for the MN10300
processors. This is the default.
@item -mno-mult-bug
+@opindex mno-mult-bug
Do not generate code to avoid bugs in the multiply instructions for the
MN10300 processors.
@item -mam33
+@opindex mam33
Generate code which uses features specific to the AM33 processor.
@item -mno-am33
+@opindex mno-am33
Do not generate code which uses features specific to the AM33 processor. This
is the default.
@item -mrelax
+@opindex mrelax
Indicate to the linker that it should perform a relaxation optimization pass
to shorten branches, calls and absolute memory addresses. This option only
has an effect when used on the command line for the final link step.
@table @gcctabopt
@item -mcode-model=small
+@opindex mcode-model=small
Assume all objects live in the lower 16MB of memory (so that their addresses
can be loaded with the @code{ld24} instruction), and assume all subroutines
are reachable with the @code{bl} instruction.
@code{model} attribute.
@item -mcode-model=medium
+@opindex mcode-model=medium
Assume objects may be anywhere in the 32-bit address space (the compiler
will generate @code{seth/add3} instructions to load their addresses), and
assume all subroutines are reachable with the @code{bl} instruction.
@item -mcode-model=large
+@opindex mcode-model=large
Assume objects may be anywhere in the 32-bit address space (the compiler
will generate @code{seth/add3} instructions to load their addresses), and
assume subroutines may not be reachable with the @code{bl} instruction
instruction sequence).
@item -msdata=none
+@opindex msdata=none
Disable use of the small data area. Variables will be put into
one of @samp{.data}, @samp{bss}, or @samp{.rodata} (unless the
@code{section} attribute has been specified).
@code{section} attribute using one of these sections.
@item -msdata=sdata
+@opindex msdata=sdata
Put small global and static data in the small data area, but do not
generate special code to reference them.
@item -msdata=use
+@opindex msdata=use
Put small global and static data in the small data area, and generate
special instructions to reference them.
@item -G @var{num}
+@opindex G
@cindex smaller data references
Put global and static objects less than or equal to @var{num} bytes
into the small data or bss sections instead of the normal data or bss
@table @gcctabopt
@item -m88000
-@kindex -m88000
+@opindex m88000
Generate code that works well on both the m88100 and the
m88110.
@item -m88100
-@kindex -m88100
+@opindex m88100
Generate code that works best for the m88100, but that also
runs on the m88110.
@item -m88110
-@kindex -m88110
+@opindex m88110
Generate code that works best for the m88110, and may not run
on the m88100.
@item -mbig-pic
-@kindex -mbig-pic
+@opindex mbig-pic
Obsolete option to be removed from the next revision.
Use @samp{-fPIC}.
@item -midentify-revision
-@kindex -midentify-revision
-@kindex ident
+@opindex midentify-revision
@cindex identifying source, compiler (88k)
Include an @code{ident} directive in the assembler output recording the
source file name, compiler name and version, timestamp, and compilation
flags used.
@item -mno-underscores
-@kindex -mno-underscores
+@opindex mno-underscores
@cindex underscores, avoiding (88k)
In assembler output, emit symbol names without adding an underscore
character at the beginning of each name. The default is to use an
@item -mocs-debug-info
@itemx -mno-ocs-debug-info
-@kindex -mocs-debug-info
-@kindex -mno-ocs-debug-info
+@opindex mocs-debug-info
+@opindex mno-ocs-debug-info
@cindex OCS (88k)
@cindex debugging, 88k OCS
Include (or omit) additional debugging information (about registers used
omit this information by default.
@item -mocs-frame-position
-@kindex -mocs-frame-position
+@opindex mocs-frame-position
@cindex register positions in frame (88k)
When emitting COFF debugging information for automatic variables and
parameters stored on the stack, use the offset from the canonical frame
@samp{-mno-ocs-frame-position}.
@item -mno-ocs-frame-position
-@kindex -mno-ocs-frame-position
+@opindex mno-ocs-frame-position
@cindex register positions in frame (88k)
When emitting COFF debugging information for automatic variables and
parameters stored on the stack, use the offset from the frame pointer
@item -moptimize-arg-area
@itemx -mno-optimize-arg-area
-@kindex -moptimize-arg-area
-@kindex -mno-optimize-arg-area
+@opindex moptimize-arg-area
+@opindex mno-optimize-arg-area
@cindex arguments in frame (88k)
Control how function arguments are stored in stack frames.
@samp{-moptimize-arg-area} saves space by optimizing them, but this
GCC does not optimize the argument area.
@item -mshort-data-@var{num}
-@kindex -mshort-data-@var{num}
+@opindex mshort-data
@cindex smaller data references (88k)
@cindex r0-relative references (88k)
Generate smaller data references by making them relative to @code{r0},
than 64k.
@item -mserialize-volatile
-@kindex -mserialize-volatile
+@opindex mserialize-volatile
@itemx -mno-serialize-volatile
-@kindex -mno-serialize-volatile
+@opindex mno-serialize-volatile
@cindex sequential consistency on 88k
Do, or don't, generate code to guarantee sequential consistency
of volatile memory references. By default, consistency is
@item -msvr4
@itemx -msvr3
-@kindex -msvr4
-@kindex -msvr3
+@opindex msvr4
+@opindex msvr3
@cindex assembler syntax, 88k
@cindex SVr4
Turn on (@samp{-msvr4}) or off (@samp{-msvr3}) compiler extensions
other m88k configurations.
@item -mversion-03.00
-@kindex -mversion-03.00
+@opindex mversion-03.00
This option is obsolete, and is ignored.
@c ??? which asm syntax better for GAS? option there too?
@item -mno-check-zero-division
@itemx -mcheck-zero-division
-@kindex -mno-check-zero-division
-@kindex -mcheck-zero-division
+@opindex mno-check-zero-division
+@opindex mcheck-zero-division
@cindex zero division on 88k
Do, or don't, generate code to guarantee that integer division by
zero will be detected. By default, detection is guaranteed.
zero-valued divisors are generated.
@item -muse-div-instruction
-@kindex -muse-div-instruction
+@opindex muse-div-instruction
@cindex divide instruction, 88k
Use the div instruction for signed integer division on the
MC88100 processor. By default, the div instruction is not used.
@item -mtrap-large-shift
@itemx -mhandle-large-shift
-@kindex -mtrap-large-shift
-@kindex -mhandle-large-shift
+@opindex mtrap-large-shift
+@opindex mhandle-large-shift
@cindex bit shift overflow (88k)
@cindex large bit shifts (88k)
Include code to detect bit-shifts of more than 31 bits; respectively,
makes no special provision for large bit shifts.
@item -mwarn-passed-structs
-@kindex -mwarn-passed-structs
+@opindex mwarn-passed-structs
@cindex structure passing (88k)
Warn when a function passes a struct as an argument or result.
Structure-passing conventions have changed during the evolution of the C
@itemx -mno-powerpc-gfxopt
@itemx -mpowerpc64
@itemx -mno-powerpc64
-@kindex -mpower
-@kindex -mpower2
-@kindex -mpowerpc
-@kindex -mpowerpc-gpopt
-@kindex -mpowerpc-gfxopt
-@kindex -mpowerpc64
+@opindex mpower
+@opindex mno-power
+@opindex mpower2
+@opindex mno-power2
+@opindex mpowerpc
+@opindex mno-powerpc
+@opindex mpowerpc-gpopt
+@opindex mno-powerpc-gpopt
+@opindex mpowerpc-gfxopt
+@opindex mno-powerpc-gfxopt
+@opindex mpowerpc64
+@opindex mno-powerpc64
GCC supports two related instruction set architectures for the
RS/6000 and PowerPC. The @dfn{POWER} instruction set are those
instructions supported by the @samp{rios} chip set used in the original
@item -mnew-mnemonics
@itemx -mold-mnemonics
-@kindex -mnew-mnemonics
-@kindex -mold-mnemonics
+@opindex mnew-mnemonics
+@opindex mold-mnemonics
Select which mnemonics to use in the generated assembler code.
@samp{-mnew-mnemonics} requests output that uses the assembler mnemonics
defined for the PowerPC architecture, while @samp{-mold-mnemonics}
@samp{-mold-mnemonics}, but should instead accept the default.
@item -mcpu=@var{cpu_type}
-@kindex -mcpu
+@opindex mcpu
Set architecture type, register usage, choice of mnemonics, and
instruction scheduling parameters for machine type @var{cpu_type}.
Supported values for @var{cpu_type} are @samp{rios}, @samp{rios1},
enables the @samp{-msoft-float} option.
@item -mtune=@var{cpu_type}
+@opindex mtune
Set the instruction scheduling parameters for machine type
@var{cpu_type}, but do not set the architecture type, register usage,
choice of mnemonics like @samp{-mcpu=}@var{cpu_type} would. The same
@itemx -mno-fp-in-toc
@itemx -mno-sum-in-toc
@itemx -mminimal-toc
-@kindex -mminimal-toc
+@opindex mfull-toc
+@opindex mno-fp-in-toc
+@opindex mno-sum-in-toc
+@opindex mminimal-toc
Modify generation of the TOC (Table Of Contents), which is created for
every executable file. The @samp{-mfull-toc} option is selected by
default. In that case, GCC will allocate at least one TOC entry for
@item -maix64
@itemx -maix32
-@kindex -maix64
-@kindex -maix32
+@opindex maix64
+@opindex maix32
Enable 64-bit AIX ABI and calling convention: 64-bit pointers, 64-bit
@code{long} type, and the infrastructure needed to support them.
Specifying @samp{-maix64} implies @samp{-mpowerpc64} and
@item -mxl-call
@itemx -mno-xl-call
-@kindex -mxl-call
+@opindex mxl-call
+@opindex mno-xl-call
On AIX, pass floating-point arguments to prototyped functions beyond the
register save area (RSA) on the stack in addition to argument FPRs. The
AIX calling convention was extended but not initially documented to
XL compilers without optimization.
@item -mthreads
-@kindex -mthreads
+@opindex mthreads
Support @dfn{AIX Threads}. Link an application written to use
@dfn{pthreads} with special libraries and startup code to enable the
application to run.
@item -mpe
-@kindex -mpe
+@opindex mpe
Support @dfn{IBM RS/6000 SP} @dfn{Parallel Environment} (PE). Link an
application written to use message passing with special startup code to
enable the application to run. The system must have PE installed in the
@item -msoft-float
@itemx -mhard-float
-@kindex -msoft-float
+@opindex msoft-float
+@opindex mhard-float
Generate code that does not use (uses) the floating-point register set.
Software floating point emulation is provided if you use the
@samp{-msoft-float} option, and pass the option to GCC when linking.
@item -mmultiple
@itemx -mno-multiple
+@opindex mmultiple
+@opindex mno-multiple
Generate code that uses (does not use) the load multiple word
instructions and the store multiple word instructions. These
instructions are generated by default on POWER systems, and not
@item -mstring
@itemx -mno-string
-@kindex -mstring
+@opindex mstring
+@opindex mno-string
Generate code that uses (does not use) the load string instructions
and the store string word instructions to save multiple registers and
do small block moves. These instructions are generated by default on
@item -mupdate
@itemx -mno-update
-@kindex -mupdate
+@opindex mupdate
+@opindex mno-update
Generate code that uses (does not use) the load or store instructions
that update the base register to the address of the calculated memory
location. These instructions are generated by default. If you use
@item -mfused-madd
@itemx -mno-fused-madd
-@kindex -mfused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
Generate code that uses (does not use) the floating point multiply and
accumulate instructions. These instructions are generated by default if
hardware floating is used.
@item -mno-bit-align
@itemx -mbit-align
-@kindex -mbit-align
+@opindex mno-bit-align
+@opindex mbit-align
On System V.4 and embedded PowerPC systems do not (do) force structures
and unions that contain bit fields to be aligned to the base type of the
bit field.
@item -mno-strict-align
@itemx -mstrict-align
-@kindex -mstrict-align
+@opindex mno-strict-align
+@opindex mstrict-align
On System V.4 and embedded PowerPC systems do not (do) assume that
unaligned memory references will be handled by the system.
@item -mrelocatable
@itemx -mno-relocatable
-@kindex -mrelocatable
+@opindex mrelocatable
+@opindex mno-relocatable
On embedded PowerPC systems generate code that allows (does not allow)
the program to be relocated to a different address at runtime. If you
use @samp{-mrelocatable} on any module, all objects linked together must
@item -mrelocatable-lib
@itemx -mno-relocatable-lib
+@opindex mrelocatable-lib
+@opindex mno-relocatable-lib
On embedded PowerPC systems generate code that allows (does not allow)
the program to be relocated to a different address at runtime. Modules
compiled with @samp{-mrelocatable-lib} can be linked with either modules
@item -mno-toc
@itemx -mtoc
+@opindex mno-toc
+@opindex mtoc
On System V.4 and embedded PowerPC systems do not (do) assume that
register 2 contains a pointer to a global area pointing to the addresses
used in the program.
@item -mlittle
@itemx -mlittle-endian
+@opindex mlittle
+@opindex mlittle-endian
On System V.4 and embedded PowerPC systems compile code for the
processor in little endian mode. The @samp{-mlittle-endian} option is
the same as @samp{-mlittle}.
@item -mbig
@itemx -mbig-endian
+@opindex mbig
+@opindex mbig-endian
On System V.4 and embedded PowerPC systems compile code for the
processor in big endian mode. The @samp{-mbig-endian} option is
the same as @samp{-mbig}.
@item -mcall-sysv
+@opindex mcall-sysv
On System V.4 and embedded PowerPC systems compile code using calling
conventions that adheres to the March 1995 draft of the System V
Application Binary Interface, PowerPC processor supplement. This is the
default unless you configured GCC using @samp{powerpc-*-eabiaix}.
@item -mcall-sysv-eabi
+@opindex mcall-sysv-eabi
Specify both @samp{-mcall-sysv} and @samp{-meabi} options.
@item -mcall-sysv-noeabi
+@opindex mcall-sysv-noeabi
Specify both @samp{-mcall-sysv} and @samp{-mno-eabi} options.
@item -mcall-aix
+@opindex mcall-aix
On System V.4 and embedded PowerPC systems compile code using calling
conventions that are similar to those used on AIX. This is the
default if you configured GCC using @samp{powerpc-*-eabiaix}.
@item -mcall-solaris
+@opindex mcall-solaris
On System V.4 and embedded PowerPC systems compile code for the Solaris
operating system.
@item -mcall-linux
+@opindex mcall-linux
On System V.4 and embedded PowerPC systems compile code for the
Linux-based GNU system.
@item -mprototype
@itemx -mno-prototype
+@opindex mprototype
+@opindex mno-prototype
On System V.4 and embedded PowerPC systems assume that all calls to
variable argument functions are properly prototyped. Otherwise, the
compiler must insert an instruction before every non prototyped call to
will set or clear the bit.
@item -msim
+@opindex msim
On embedded PowerPC systems, assume that the startup module is called
@file{sim-crt0.o} and that the standard C libraries are @file{libsim.a} and
@file{libc.a}. This is the default for @samp{powerpc-*-eabisim}.
configurations.
@item -mmvme
+@opindex mmvme
On embedded PowerPC systems, assume that the startup module is called
@file{crt0.o} and the standard C libraries are @file{libmvme.a} and
@file{libc.a}.
@item -mads
+@opindex mads
On embedded PowerPC systems, assume that the startup module is called
@file{crt0.o} and the standard C libraries are @file{libads.a} and
@file{libc.a}.
@item -myellowknife
+@opindex myellowknife
On embedded PowerPC systems, assume that the startup module is called
@file{crt0.o} and the standard C libraries are @file{libyk.a} and
@file{libc.a}.
@item -mvxworks
+@opindex mvxworks
On System V.4 and embedded PowerPC systems, specify that you are
compiling for a VxWorks system.
@item -memb
+@opindex memb
On embedded PowerPC systems, set the @var{PPC_EMB} bit in the ELF flags
header to indicate that @samp{eabi} extended relocations are used.
@item -meabi
@itemx -mno-eabi
+@opindex meabi
+@opindex mno-eabi
On System V.4 and embedded PowerPC systems do (do not) adhere to the
Embedded Applications Binary Interface (eabi) which is a set of
modifications to the System V.4 specifications. Selecting @option{-meabi}
configured GCC using one of the @samp{powerpc*-*-eabi*} options.
@item -msdata=eabi
+@opindex msdata=eabi
On System V.4 and embedded PowerPC systems, put small initialized
@code{const} global and static data in the @samp{.sdata2} section, which
is pointed to by register @code{r2}. Put small initialized
@samp{-msdata=eabi} option also sets the @samp{-memb} option.
@item -msdata=sysv
+@opindex msdata=sysv
On System V.4 and embedded PowerPC systems, put small global and static
data in the @samp{.sdata} section, which is pointed to by register
@code{r13}. Put small uninitialized global and static data in the
@item -msdata=default
@itemx -msdata
+@opindex msdata=default
+@opindex msdata
On System V.4 and embedded PowerPC systems, if @samp{-meabi} is used,
compile code the same as @samp{-msdata=eabi}, otherwise compile code the
same as @samp{-msdata=sysv}.
@item -msdata-data
+@opindex msdata-data
On System V.4 and embedded PowerPC systems, put small global and static
data in the @samp{.sdata} section. Put small uninitialized global and
static data in the @samp{.sbss} section. Do not use register @code{r13}
@item -msdata=none
@itemx -mno-sdata
+@opindex msdata=none
+@opindex mno-sdata
On embedded PowerPC systems, put all initialized global and static data
in the @samp{.data} section, and all uninitialized data in the
@samp{.bss} section.
@item -G @var{num}
+@opindex G
@cindex smaller data references (PowerPC)
@cindex .sdata/.sdata2 references (PowerPC)
On embedded PowerPC systems, put global and static items less than or
@item -mregnames
@itemx -mno-regnames
+@opindex mregnames
+@opindex mno-regnames
On System V.4 and embedded PowerPC systems do (do not) emit register
names in the assembly language output using symbolic forms.
@table @gcctabopt
@item -min-line-mul
+@opindex min-line-mul
Use an in-line code sequence for integer multiplies. This is the
default.
@item -mcall-lib-mul
+@opindex mcall-lib-mul
Call @code{lmul$$} for integer multiples.
@item -mfull-fp-blocks
+@opindex mfull-fp-blocks
Generate full-size floating point data blocks, including the minimum
amount of scratch space recommended by IBM. This is the default.
@item -mminimum-fp-blocks
+@opindex mminimum-fp-blocks
Do not include extra scratch space in floating point data blocks. This
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{stdargs.h} will not work with
floating point operands if this option is specified.
@item -mfp-arg-in-gregs
+@opindex mfp-arg-in-gregs
Use the normal calling convention for floating point arguments. This is
the default.
@item -mhc-struct-return
+@opindex mhc-struct-return
Return structures of more than one word in memory, rather than in a
register. This provides compatibility with the MetaWare HighC (hc)
compiler. Use the option @samp{-fpcc-struct-return} for compatibility
with the Portable C Compiler (pcc).
@item -mnohc-struct-return
+@opindex mnohc-struct-return
Return some structures of more than one word in registers, when
convenient. This is the default. For compatibility with the
IBM-supplied compilers, use the option @samp{-fpcc-struct-return} or the
@table @gcctabopt
@item -mcpu=@var{cpu type}
+@opindex mcpu
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},
or @samp{-mabi} switch being used.
@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.
@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.
@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.
@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.
@item -mfp32
+@opindex mfp32
Assume that 32 32-bit floating point registers are available. This is
the default.
@item -mfp64
+@opindex mfp64
Assume that 32 64-bit floating point registers are available. This is
the default when the @samp{-mips3} option is used.
@item -mgp32
+@opindex mgp32
Assume that 32 32-bit general purpose registers are available. This is
the default.
@item -mgp64
+@opindex mgp64
Assume that 32 64-bit general purpose registers are available. This is
the default when the @samp{-mips3} option is used.
@item -mint64
+@opindex mint64
Force int and long types to be 64 bits wide. See @samp{-mlong32} for an
explanation of the default, and the width of pointers.
@item -mlong64
+@opindex mlong64
Force long types to be 64 bits wide. See @samp{-mlong32} for an
explanation of the default, and the width of pointers.
@item -mlong32
+@opindex mlong32
Force long, int, and pointer types to be 32 bits wide.
If none of @samp{-mlong32}, @samp{-mlong64}, or @samp{-mint64} are set,
@itemx -mabi=n32
@itemx -mabi=64
@itemx -mabi=eabi
+@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
@samp{-mips1} for @samp{32}, @samp{-mips3} for @samp{n32}, and
@samp{-mips4} otherwise. Conversely, with @samp{-mips1} or
is @samp{64}.
@item -mmips-as
+@opindex mmips-as
Generate code for the MIPS assembler, and invoke @file{mips-tfile} to
add normal debug information. This is the default for all
platforms except for the OSF/1 reference platform, using the OSF/rose
stabs within MIPS ECOFF.
@item -mgas
+@opindex mgas
Generate code for the GNU assembler. This is the default on the OSF/1
reference platform, using the OSF/rose object format. Also, this is
the default if the configure option @samp{--with-gnu-as} is used.
@item -msplit-addresses
@itemx -mno-split-addresses
+@opindex msplit-addresses
+@opindex mno-split-addresses
Generate code to load the high and low parts of address constants separately.
This allows @code{gcc} to optimize away redundant loads of the high order
bits of addresses. This optimization requires GNU as and GNU ld.
@item -mrnames
@itemx -mno-rnames
+@opindex mrnames
+@opindex mno-rnames
The @samp{-mrnames} switch says to output code using the MIPS software
names for the registers, instead of the hardware names (ie, @var{a0}
instead of @var{$4}). The only known assembler that supports this option
@item -mgpopt
@itemx -mno-gpopt
+@opindex mgpopt
+@opindex mno-gpopt
The @samp{-mgpopt} switch says to write all of the data declarations
before the instructions in the text section, this allows the MIPS
assembler to generate one word memory references instead of using two
@item -mstats
@itemx -mno-stats
+@opindex mstats
+@opindex mno-stats
For each non-inline function processed, the @samp{-mstats} switch
causes the compiler to emit one line to the standard error file to
print statistics about the program (number of registers saved, stack
@item -mmemcpy
@itemx -mno-memcpy
+@opindex mmemcpy
+@opindex mno-memcpy
The @samp{-mmemcpy} switch makes all block moves call the appropriate
string function (@samp{memcpy} or @samp{bcopy}) instead of possibly
generating inline code.
@item -mmips-tfile
@itemx -mno-mips-tfile
+@opindex mmips-tfile
+@opindex mno-mips-tfile
The @samp{-mno-mips-tfile} switch causes the compiler not
postprocess the object file with the @file{mips-tfile} program,
after the MIPS assembler has generated it to add debug support. If
prevents compilation.
@item -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not part of GCC.
Normally the facilities of the machine's usual C compiler are used, but
cross-compilation.
@item -mhard-float
+@opindex mhard-float
Generate output containing floating point instructions. This is the
default if you use the unmodified sources.
@item -mabicalls
@itemx -mno-abicalls
+@opindex mabicalls
+@opindex mno-abicalls
Emit (or do not emit) the pseudo operations @samp{.abicalls},
@samp{.cpload}, and @samp{.cprestore} that some System V.4 ports use for
position independent code.
@item -mlong-calls
@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
Do all calls with the @samp{JALR} instruction, which requires
loading up a function's address into a register before the call.
You need to use this switch, if you call outside of the current
@item -mhalf-pic
@itemx -mno-half-pic
+@opindex mhalf-pic
+@opindex mno-half-pic
Put pointers to extern references into the data section and load them
up, rather than put the references in the text section.
@item -membedded-pic
@itemx -mno-embedded-pic
+@opindex membedded-pic
+@opindex mno-embedded-pic
Generate PIC code suitable for some embedded systems. All calls are
made using PC relative address, and all data is addressed using the $gp
register. No more than 65536 bytes of global data may be used. This
@item -membedded-data
@itemx -mno-embedded-data
+@opindex membedded-data
+@opindex mno-embedded-data
Allocate variables to the read-only data section first if possible, then
next in the small data section if possible, otherwise in data. This gives
slightly slower code than the default, but reduces the amount of RAM required
@item -muninit-const-in-rodata
@itemx -mno-uninit-const-in-rodata
+@opindex muninit-const-in-rodata
+@opindex mno-uninit-const-in-rodata
When used together with -membedded-data, it will always store uninitialized
const variables in the read-only data section.
@item -msingle-float
@itemx -mdouble-float
+@opindex msingle-float
+@opindex mdouble-float
The @samp{-msingle-float} switch tells gcc to assume that the floating
point coprocessor only supports single precision operations, as on the
@samp{r4650} chip. The @samp{-mdouble-float} switch permits gcc to use
@item -mmad
@itemx -mno-mad
+@opindex mmad
+@opindex mno-mad
Permit use of the @samp{mad}, @samp{madu} and @samp{mul} instructions,
as on the @samp{r4650} chip.
@item -m4650
+@opindex m4650
Turns on @samp{-msingle-float}, @samp{-mmad}, and, at least for now,
@samp{-mcpu=r4650}.
@item -mips16
@itemx -mno-mips16
+@opindex mips16
+@opindex mno-mips16
Enable 16-bit instructions.
@item -mentry
+@opindex mentry
Use the entry and exit pseudo ops. This option can only be used with
@samp{-mips16}.
@item -EL
+@opindex EL
Compile code for the processor in little endian mode.
The requisite libraries are assumed to exist.
@item -EB
+@opindex EB
Compile code for the processor in big endian mode.
The requisite libraries are assumed to exist.
@item -G @var{num}
+@opindex G
@cindex smaller data references (MIPS)
@cindex gp-relative references (MIPS)
Put global and static items less than or equal to @var{num} bytes into
value.
@item -nocpp
+@opindex nocpp
Tell the MIPS assembler to not run its preprocessor over user
assembler files (with a @samp{.s} suffix) when assembling them.
@item -mfix7000
+@opindex mfix7000
Pass an option to gas which will cause nops to be inserted if
the read of the destination register of an mfhi or mflo instruction
occurs in the following two instructions.
@item -no-crt0
+@opindex no-crt0
Do not include the default crt0.
@end table
@table @gcctabopt
@item -mcpu=@var{cpu type}
+@opindex mcpu
Assume the defaults for the machine type @var{cpu type} when scheduling
instructions. The choices for @var{cpu type} are @samp{i386},
@samp{i486}, @samp{i586}, @samp{i686}, @samp{pentium},
AMD chips as opposed to the Intel ones.
@item -march=@var{cpu type}
+@opindex march
Generate instructions for the machine type @var{cpu type}. The choices
for @var{cpu type} are the same as for @samp{-mcpu}. Moreover,
specifying @samp{-march=@var{cpu type}} implies @samp{-mcpu=@var{cpu type}}.
@itemx -m486
@itemx -mpentium
@itemx -mpentiumpro
+@opindex m386
+@opindex m486
+@opindex mpentium
+@opindex mpentiumpro
Synonyms for -mcpu=i386, -mcpu=i486, -mcpu=pentium, and -mcpu=pentiumpro
respectively. These synonyms are deprecated.
@item -mintel-syntax
+@opindex mintel-syntax
Emit assembly using Intel syntax opcodes instead of AT&T syntax.
@item -mieee-fp
@itemx -mno-ieee-fp
+@opindex mieee-fp
+@opindex mno-ieee-fp
Control whether or not the compiler uses IEEE floating point
comparisons. These handle correctly the case where the result of a
comparison is unordered.
@item -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not part of GCC.
Normally the facilities of the machine's usual C compiler are used, but
@samp{-msoft-float} is used.
@item -mno-fp-ret-in-387
+@opindex mno-fp-ret-in-387
Do not use the FPU registers for return values of functions.
The usual calling convention has functions return values of types
in ordinary CPU registers instead.
@item -mno-fancy-math-387
+@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.
@item -malign-double
@itemx -mno-align-double
+@opindex malign-double
+@opindex mno-align-double
Control whether GCC aligns @code{double}, @code{long double}, and
@code{long long} variables on a two word boundary or a one word
boundary. Aligning @code{double} variables on a two word boundary will
@item -m128bit-long-double
@itemx -m128bit-long-double
+@opindex m128bit-long-double
+@opindex m128bit-long-double
Control the size of @code{long double} type. i386 application binary interface
specify the size to be 12 bytes, while modern architectures (Pentium and newer)
preffer @code{long double} aligned to 8 or 16 byte boundary. This is
@item -m96bit-long-double
@itemx -m96bit-long-double
+@opindex m96bit-long-double
+@opindex m96bit-long-double
Set the size of @code{long double} to 96 bits as required by the i386
application binary interface. This is the default.
@item -msvr3-shlib
@itemx -mno-svr3-shlib
+@opindex msvr3-shlib
+@opindex mno-svr3-shlib
Control whether GCC places uninitialized locals into @code{bss} or
@code{data}. @samp{-msvr3-shlib} places these locals into @code{bss}.
These options are meaningful only on System V Release 3.
@item -mno-wide-multiply
@itemx -mwide-multiply
+@opindex mno-wide-multiply
+@opindex mwide-multiply
Control whether GCC uses the @code{mul} and @code{imul} that produce
64-bit results in @code{eax:edx} from 32-bit operands to do @code{long
long} multiplies and 32-bit division by constants.
@item -mrtd
+@opindex mrtd
Use a different function-calling convention, in which functions that
take a fixed number of arguments return with the @code{ret} @var{num}
instruction, which pops their arguments while returning. This saves one
harmlessly ignored.)
@item -mregparm=@var{num}
+@opindex mregparm
Control how many registers are used to pass integer arguments. By
default, no registers are used to pass arguments, and at most 3
registers can be used. You can control this behavior for a specific
startup modules.
@item -mpreferred-stack-boundary=@var{num}
+@opindex mpreferred-stack-boundary
Attempt to keep the stack boundary aligned to a 2 raised to @var{num}
byte boundary. If @samp{-mpreferred-stack-boundary} is not specified,
the default is 4 (16 bytes or 128 bits).
@samp{-mpreferred-stack-boundary=2}.
@item -mpush-args
-@kindex -mpush-args
+@opindex mpush-args
Use PUSH operations to store outgoing parameters. This method is shorter
and usually equally fast as method using SUB/MOV operations and is enabled
by default. In some cases disabling it may improve performance because of
improved scheduling and reduced dependencies.
@item -maccumulate-outgoing-args
-@kindex -maccumulate-outgoing-args
+@opindex maccumulate-outgoing-args
If enabled, the maximum amount of space required for outgoing arguments will be
computed in the function prologue. This in faster on most modern CPUs
because of reduced dependencies, improved scheduling and reduced stack usage
increase in code size. This switch implies -mno-push-args.
@item -mthreads
-@kindex -mthreads
+@opindex mthreads
Support thread-safe exception handling on @samp{Mingw32}. Code that relies
on thread-safe exception handling must compile and link all code with the
@samp{-mthreads} option. When compiling, @samp{-mthreads} defines
@samp{-lmingwthrd} which cleans up per thread exception handling data.
@item -mno-align-stringops
-@kindex -mno-align-stringops
+@opindex mno-align-stringops
Do not align destination of inlined string operations. This switch reduces
code size and improves performance in case the destination is already aligned,
but gcc don't know about it.
@item -minline-all-stringops
-@kindex -minline-all-stringops
+@opindex minline-all-stringops
By default GCC inlines string operations only when destination is known to be
aligned at least to 4 byte boundary. This enables more inlining, increase code
size, but may improve performance of code that depends on fast memcpy, strlen
and memset for short lengths.
@item -momit-leaf-frame-pointer
-@kindex -momit-leaf-frame-pointer
+@opindex momit-leaf-frame-pointer
Don't keep the frame pointer in a register for leaf functions. This
avoids the instructions to save, set up and restore frame pointers and
makes an extra register available in leaf functions. The option
@table @gcctabopt
@item -march=@var{architecture type}
+@opindex march
Generate code for the specified architecture. The choices for
@var{architecture type} are @samp{1.0} for PA 1.0, @samp{1.1} for PA
1.1, and @samp{2.0} for PA 2.0 processors. Refer to
@item -mpa-risc-1-0
@itemx -mpa-risc-1-1
@itemx -mpa-risc-2-0
+@opindex mpa-risc-1-0
+@opindex mpa-risc-1-1
+@opindex mpa-risc-2-0
Synonyms for -march=1.0, -march=1.1, and -march=2.0 respectively.
@item -mbig-switch
+@opindex mbig-switch
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 -mjump-in-delay
+@opindex mjump-in-delay
Fill delay slots of function calls with unconditional jump instructions
by modifying the return pointer for the function call to be the target
of the conditional jump.
@item -mdisable-fpregs
+@opindex mdisable-fpregs
Prevent floating point registers from being used in any manner. This is
necessary for compiling kernels which perform lazy context switching of
floating point registers. If you use this option and attempt to perform
floating point operations, the compiler will abort.
@item -mdisable-indexing
+@opindex mdisable-indexing
Prevent the compiler from using indexing address modes. This avoids some
rather obscure problems when compiling MIG generated code under MACH.
@item -mno-space-regs
+@opindex mno-space-regs
Generate code that assumes the target has no space registers. This allows
GCC to generate faster indirect calls and use unscaled index address modes.
Such code is suitable for level 0 PA systems and kernels.
@item -mfast-indirect-calls
+@opindex mfast-indirect-calls
Generate code that assumes calls never cross space boundaries. This
allows GCC to emit code which performs faster indirect calls.
functions.
@item -mlong-load-store
+@opindex mlong-load-store
Generate 3-instruction load and store sequences as sometimes required by
the HP-UX 10 linker. This is equivalent to the @samp{+k} option to
the HP compilers.
@item -mportable-runtime
+@opindex mportable-runtime
Use the portable calling conventions proposed by HP for ELF systems.
@item -mgas
+@opindex mgas
Enable the use of assembler directives only GAS understands.
@item -mschedule=@var{cpu type}
+@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
proper scheduling option for your machine.
@item -mlinker-opt
+@opindex mlinker-opt
Enable the optimization pass in the HPUX linker. Note this makes symbolic
debugging impossible. It also triggers a bug in the HPUX 8 and HPUX 9 linkers
in which they give bogus error messages when linking some programs.
@item -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries are not available for all HPPA
targets. Normally the facilities of the machine's usual C compiler are
These @samp{-m} options are defined for the Intel 960 implementations:
@table @gcctabopt
-@item -m@var{cpu type}
-Assume the defaults for the machine type @var{cpu type} for some of
+@item -m@var{cpu-type}
+@opindex mka
+@opindex mkb
+@opindex mmc
+@opindex mca
+@opindex mcf
+@opindex msa
+@opindex msb
+Assume the defaults for the machine type @var{cpu-type} for some of
the other options, including instruction scheduling, floating point
-support, and addressing modes. The choices for @var{cpu type} are
+support, and addressing modes. The choices for @var{cpu-type} are
@samp{ka}, @samp{kb}, @samp{mc}, @samp{ca}, @samp{cf},
@samp{sa}, and @samp{sb}.
The default is
@item -mnumerics
@itemx -msoft-float
+@opindex mnumerics
+@opindex msoft-float
The @samp{-mnumerics} option indicates that the processor does support
floating-point instructions. The @samp{-msoft-float} option indicates
that floating-point support should not be assumed.
@item -mleaf-procedures
@itemx -mno-leaf-procedures
+@opindex mleaf-procedures
+@opindex mno-leaf-procedures
Do (or do not) attempt to alter leaf procedures to be callable with the
@code{bal} instruction as well as @code{call}. This will result in more
efficient code for explicit calls when the @code{bal} instruction can be
@item -mtail-call
@itemx -mno-tail-call
+@opindex mtail-call
+@opindex mno-tail-call
Do (or do not) make additional attempts (beyond those of the
machine-independent portions of the compiler) to optimize tail-recursive
calls into branches. You may not want to do this because the detection of
@item -mcomplex-addr
@itemx -mno-complex-addr
+@opindex mcomplex-addr
+@opindex mno-complex-addr
Assume (or do not assume) that the use of a complex addressing mode is a
win on this implementation of the i960. Complex addressing modes may not
be worthwhile on the K-series, but they definitely are on the C-series.
@item -mcode-align
@itemx -mno-code-align
+@opindex mcode-align
+@opindex mno-code-align
Align code to 8-byte boundaries for faster fetching (or don't bother).
Currently turned on by default for C-series implementations only.
@ignore
@item -mclean-linkage
@itemx -mno-clean-linkage
+@opindex mclean-linkage
+@opindex mno-clean-linkage
These options are not fully implemented.
@end ignore
@item -mic-compat
@itemx -mic2.0-compat
@itemx -mic3.0-compat
+@opindex mic-compat
+@opindex mic2.0-compat
+@opindex mic3.0-compat
Enable compatibility with iC960 v2.0 or v3.0.
@item -masm-compat
@itemx -mintel-asm
+@opindex masm-compat
+@opindex mintel-asm
Enable compatibility with the iC960 assembler.
@item -mstrict-align
@itemx -mno-strict-align
+@opindex mstrict-align
+@opindex mno-strict-align
Do not permit (do permit) unaligned accesses.
@item -mold-align
+@opindex mold-align
Enable structure-alignment compatibility with Intel's gcc release version
1.3 (based on gcc 1.37). This option implies @samp{-mstrict-align}.
@item -mlong-double-64
+@opindex mlong-double-64
Implement type @samp{long double} as 64-bit floating point numbers.
Without the option @samp{long double} is implemented by 80-bit
floating point numbers. The only reason we have it because there is
@table @gcctabopt
@item -mno-soft-float
@itemx -msoft-float
+@opindex mno-soft-float
+@opindex msoft-float
Use (do not use) the hardware floating-point instructions for
floating-point operations. When @option{-msoft-float} is specified,
functions in @file{libgcc.a} will be used to perform floating-point
@item -mfp-reg
@itemx -mno-fp-regs
+@opindex mfp-reg
+@opindex mno-fp-regs
Generate code that uses (does not use) the floating-point register set.
@option{-mno-fp-regs} implies @option{-msoft-float}. If the floating-point
register set is not used, floating point operands are passed in integer
and hence need not save and restore, any floating-point registers.
@item -mieee
+@opindex mieee
The Alpha architecture implements floating-point hardware optimized for
maximum performance. It is mostly compliant with the IEEE floating
point standard. However, for full compliance, software assistance is
@option{-ieee_with_no_inexact}.
@item -mieee-with-inexact
+@opindex mieee-with-inexact
@c overfull hbox here --bob 22 jul96
@c original text between ignore ... end ignore
@ignore
@c end changes to prevent overfull hboxes
@item -mfp-trap-mode=@var{trap mode}
+@opindex mfp-trap-mode
This option controls what floating-point related traps are enabled.
Other Alpha compilers call this option @samp{-fptm }@var{trap mode}.
The trap mode can be set to one of four values:
@end table
@item -mfp-rounding-mode=@var{rounding mode}
+@opindex mfp-rounding-mode
Selects the IEEE rounding mode. Other Alpha compilers call this option
@samp{-fprm }@var{rounding mode}. The @var{rounding mode} can be one
of:
@end table
@item -mtrap-precision=@var{trap precision}
+@opindex mtrap-precision
In the Alpha architecture, floating point traps are imprecise. This
means without software assistance it is impossible to recover from a
floating trap and program execution normally needs to be terminated.
@samp{-scope_safe} and @samp{-resumption_safe}.
@item -mieee-conformant
+@opindex mieee-conformant
This option marks the generated code as IEEE conformant. You must not
use this option unless you also specify @samp{-mtrap-precision=i} and either
@samp{-mfp-trap-mode=su} or @samp{-mfp-trap-mode=sui}. Its only effect
IEEE-conformant math library routines will be linked in.
@item -mbuild-constants
+@opindex mbuild-constants
Normally GCC examines a 32- or 64-bit integer constant to
see if it can construct it from smaller constants in two or three
instructions. If it cannot, it will output the constant as a literal and
@item -malpha-as
@itemx -mgas
+@opindex malpha-as
+@opindex mgas
Select whether to generate code to be assembled by the vendor-supplied
assembler (@samp{-malpha-as}) or by the GNU assembler @samp{-mgas}.
@itemx -mno-cix
@itemx -mmax
@itemx -mno-max
+@opindex mbwx
+@opindex mno-bwx
+@opindex mcix
+@opindex mno-cix
+@opindex mmax
+@opindex mno-max
Indicate whether GCC should generate code to use the optional BWX,
CIX, and MAX instruction sets. The default is to use the instruction sets
supported by the CPU type specified via @samp{-mcpu=} option or that
of the CPU on which GCC was built if none was specified.
@item -mcpu=@var{cpu_type}
+@opindex mcpu
Set the instruction set, register set, and instruction scheduling
parameters for machine type @var{cpu_type}. You can specify either the
@samp{EV} style name or the corresponding chip number. GCC
@end table
@item -mmemory-latency=@var{time}
+@opindex mmemory-latency
Sets the latency the scheduler should assume for typical memory
references as seen by the application. This number is highly
dependent on the memory access patterns used by the application
@table @gcctabopt
@item -mc300
+@opindex mc300
Produce code for a C300 Clipper processor. This is the default.
@item -mc400
+@opindex mc400
Produce code for a C400 Clipper processor i.e. use floating point
registers f8..f15.
@end table
@table @gcctabopt
@item -mrelax
+@opindex mrelax
Shorten some address references at link time, when possible; uses the
linker option @samp{-relax}. @xref{H8/300,, @code{ld} and the H8/300,
ld.info, Using ld}, for a fuller description.
@item -mh
+@opindex mh
Generate code for the H8/300H.
@item -ms
+@opindex ms
Generate code for the H8/S.
@item -ms2600
+@opindex ms2600
Generate code for the H8/S2600. This switch must be used with -ms.
@item -mint32
+@opindex mint32
Make @code{int} data 32 bits by default.
@item -malign-300
+@opindex malign-300
On the H8/300H and H8/S, use the same alignment rules as for the H8/300.
The default for the H8/300H and H8/S is to align longs and floats on 4
byte boundaries.
@table @gcctabopt
@item -m1
+@opindex m1
Generate code for the SH1.
@item -m2
+@opindex m2
Generate code for the SH2.
@item -m3
+@opindex m3
Generate code for the SH3.
@item -m3e
+@opindex m3e
Generate code for the SH3e.
@item -m4-nofpu
+@opindex m4-nofpu
Generate code for the SH4 without a floating-point unit.
@item -m4-single-only
+@opindex m4-single-only
Generate code for the SH4 with a floating-point unit that only
supports single-precision arithmentic.
@item -m4-single
+@opindex m4-single
Generate code for the SH4 assuming the floating-point unit is in
single-precision mode by default.
@item -m4
+@opindex m4
Generate code for the SH4.
@item -mb
+@opindex mb
Compile code for the processor in big endian mode.
@item -ml
+@opindex ml
Compile code for the processor in little endian mode.
@item -mdalign
+@opindex mdalign
Align doubles at 64-bit boundaries. Note that this changes the calling
conventions, and thus some functions from the standard C library will
not work unless you recompile it first with -mdalign.
@item -mrelax
+@opindex mrelax
Shorten some address references at link time, when possible; uses the
linker option @samp{-relax}.
@item -mbigtable
+@opindex mbigtable
Use 32-bit offsets in @code{switch} tables. The default is to use
16-bit offsets.
@item -mfmovd
+@opindex mfmovd
Enable the use of the instruction @code{fmovd}.
@item -mhitachi
+@opindex mhitachi
Comply with the calling conventions defined by Hitachi.
@item -mnomacsave
+@opindex mnomacsave
Mark the @code{MAC} register as call-clobbered, even if
@option{-mhitachi} is given.
@item -misize
+@opindex misize
Dump instruction size and location in the assembly code.
@item -mpadstruct
+@opindex mpadstruct
This option is deprecated. It pads structures to multiple of 4 bytes,
which is incompatible with the SH ABI.
@item -mspace
+@opindex mspace
Optimize for space instead of speed. Implied by @option{-Os}.
@item -mprefergot
+@opindex mprefergot
When generating position-independent code, emit function calls using
the Global Offset Table instead of the Procedure Linkage Table.
@item -musermode
+@opindex musermode
Generate a library function call to invalidate instruction cache
entries, after fixing up a trampoline. This library function call
doesn't assume it can write to the whole memory address space. This
@table @gcctabopt
@item -G
+@opindex G
Create a shared object.
It is recommended that @samp{-symbolic} or @samp{-shared} be used instead.
@item -Qy
+@opindex Qy
Identify the versions of each tool used by the compiler, in a
@code{.ident} assembler directive in the output.
@item -Qn
+@opindex Qn
Refrain from adding @code{.ident} directives to the output file (this is
the default).
@item -YP\,@var{dirs}
+@opindex YP
Search the directories @var{dirs}, and no others, for libraries
specified with @samp{-l}.
@item -Ym\,@var{dir}
+@opindex Ym
Look in the directory @var{dir} to find the M4 preprocessor.
The assembler uses this option.
@c This is supposed to go with a -Yd for predefined M4 macro files, but
@table @gcctabopt
@item -mcpu=@var{cpu_type}
+@opindex mcpu
Set the instruction set, register set, and instruction scheduling
parameters for machine type @var{cpu_type}. Supported values for
@var{cpu_type} are @samp{c30}, @samp{c31}, @samp{c32}, @samp{c40}, and
@item -mbig
@itemx -msmall-memory
@itemx -msmall
+@opindex mbig-memory
+@opindex mbig
+@opindex msmall-memory
+@opindex msmall
Generates code for the big or small memory model. The small memory
model assumed that all data fits into one 64K word page. At run-time
the data page (DP) register must be set to point to the 64K page
@item -mbk
@itemx -mno-bk
+@opindex mbk
+@opindex mno-bk
Allow (disallow) allocation of general integer operands into the block
count register BK.
@item -mdb
@itemx -mno-db
+@opindex mdb
+@opindex mno-db
Enable (disable) generation of code using decrement and branch,
DBcond(D), instructions. This is enabled by default for the C4x. To be
on the safe side, this is disabled for the C3x, since the maximum
@item -mdp-isr-reload
@itemx -mparanoid
+@opindex mdp-isr-reload
+@opindex mparanoid
Force the DP register to be saved on entry to an interrupt service
routine (ISR), reloaded to point to the data section, and restored on
exit from the ISR. This should not be required unless someone has
@item -mmpyi
@itemx -mno-mpyi
+@opindex mmpyi
+@opindex mno-mpyi
For the C3x use the 24-bit MPYI instruction for integer multiplies
instead of a library call to guarantee 32-bit results. Note that if one
of the operands is a constant, then the multiplication will be performed
@item -mfast-fix
@itemx -mno-fast-fix
+@opindex mfast-fix
+@opindex mno-fast-fix
The C3x/C4x FIX instruction to convert a floating point value to an
integer value chooses the nearest integer less than or equal to the
floating point value rather than to the nearest integer. Thus if the
@item -mrptb
@itemx -mno-rptb
+@opindex mrptb
+@opindex mno-rptb
Enable (disable) generation of repeat block sequences using the RPTB
instruction for zero overhead looping. The RPTB construct is only used
for innermost loops that do not call functions or jump across the loop
@item -mrpts=@var{count}
@itemx -mno-rpts
+@opindex mrpts
+@opindex mno-rpts
Enable (disable) the use of the single instruction repeat instruction
RPTS. If a repeat block contains a single instruction, and the loop
count can be guaranteed to be less than the value @var{count}, GCC will
@item -mloop-unsigned
@itemx -mno-loop-unsigned
+@opindex mloop-unsigned
+@opindex mno-loop-unsigned
The maximum iteration count when using RPTS and RPTB (and DB on the C40)
is 2^31 + 1 since these instructions test if the iteration count is
negative to terminate the loop. If the iteration count is unsigned
exceeded. This switch allows an unsigned iteration count.
@item -mti
+@opindex mti
Try to emit an assembler syntax that the TI assembler (asm30) is happy
with. This also enforces compatibility with the API employed by the TI
C3x C compiler. For example, long doubles are passed as structures
@item -mregparm
@itemx -mmemparm
+@opindex mregparm
+@opindex mmemparm
Generate code that uses registers (stack) for passing arguments to functions.
By default, arguments are passed in registers where possible rather
than by pushing arguments on to the stack.
@item -mparallel-insns
@itemx -mno-parallel-insns
+@opindex mparallel-insns
+@opindex mno-parallel-insns
Allow the generation of parallel instructions. This is enabled by
default with -O2.
@item -mparallel-mpy
@itemx -mno-parallel-mpy
+@opindex mparallel-mpy
+@opindex mno-parallel-mpy
Allow the generation of MPY||ADD and MPY||SUB parallel instructions,
provided -mparallel-insns is also specified. These instructions have
tight register constraints which can pessimize the code generation
@table @gcctabopt
@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 always load the functions address up into a
register, and call indirect through the pointer.
@item -mno-ep
@itemx -mep
+@opindex mno-ep
+@opindex mep
Do not optimize (do optimize) basic blocks that use the same index
pointer 4 or more times to copy pointer into the @code{ep} register, and
use the shorter @code{sld} and @code{sst} instructions. The @samp{-mep}
@item -mno-prolog-function
@itemx -mprolog-function
+@opindex mno-prolog-function
+@opindex mprolog-function
Do not use (do use) external functions to save and restore registers at
the prolog and epilog of a function. The external functions are slower,
but use less code space if more than one function saves the same number
you optimize.
@item -mspace
+@opindex mspace
Try to make the code as small as possible. At present, this just turns
on the @samp{-mep} and @samp{-mprolog-function} options.
@item -mtda=@var{n}
+@opindex mtda
Put static or global variables whose size is @var{n} bytes or less into
the tiny data area that register @code{ep} points to. The tiny data
area can hold up to 256 bytes in total (128 bytes for byte references).
@item -msda=@var{n}
+@opindex msda
Put static or global variables whose size is @var{n} bytes or less into
the small data area that register @code{gp} points to. The small data
area can hold up to 64 kilobytes.
@item -mzda=@var{n}
+@opindex mzda
Put static or global variables whose size is @var{n} bytes or less into
the first 32 kilobytes of memory.
@item -mv850
+@opindex mv850
Specify that the target processor is the V850.
@item -mbig-switch
+@opindex mbig-switch
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.
@table @gcctabopt
@item -EL
+@opindex EL
Compile code for little endian mode. This is the default.
@item -EB
+@opindex EB
Compile code for big endian mode.
@item -mmangle-cpu
+@opindex mmangle-cpu
Prepend the name of the cpu to all public symbol names.
In multiple-processor systems, there are many ARC variants with different
instruction and register set characteristics. This flag prevents code
This is an all or nothing option.
@item -mcpu=@var{cpu}
+@opindex mcpu
Compile code for ARC variant @var{cpu}.
Which variants are supported depend on the configuration.
All variants support @samp{-mcpu=base}, this is the default.
@item -mtext=@var{text section}
@itemx -mdata=@var{data section}
@itemx -mrodata=@var{readonly data section}
+@opindex mtext
+@opindex mdata
+@opindex mrodata
Put functions, data, and readonly data in @var{text section},
@var{data section}, and @var{readonly data section} respectively
by default. This can be overridden with the @code{section} attribute.
@table @gcctabopt
@item -m32032
@itemx -m32032
+@opindex m32032
+@opindex m32032
Generate output for a 32032. This is the default
when the compiler is configured for 32032 and 32016 based systems.
@item -m32332
@itemx -m32332
+@opindex m32332
+@opindex m32332
Generate output for a 32332. This is the default
when the compiler is configured for 32332-based systems.
@item -m32532
@itemx -m32532
+@opindex m32532
+@opindex m32532
Generate output for a 32532. This is the default
when the compiler is configured for 32532-based systems.
@item -m32081
+@opindex m32081
Generate output containing 32081 instructions for floating point.
This is the default for all systems.
@item -m32381
+@opindex m32381
Generate output containing 32381 instructions for floating point. This
also implies @samp{-m32081}. The 32381 is only compatible with the 32332
and 32532 cpus. This is the default for the pc532-netbsd configuration.
@item -mmulti-add
+@opindex mmulti-add
Try and generate multiply-add floating point instructions @code{polyF}
and @code{dotF}. This option is only available if the @samp{-m32381}
option is in effect. Using these instructions requires changes to to
particularly likely to make heavy use of multiply-add instructions.
@item -mnomulti-add
+@opindex mnomulti-add
Do not try and generate multiply-add floating point instructions
@code{polyF} and @code{dotF}. This is the default on all platforms.
@item -msoft-float
+@opindex msoft-float
Generate output containing library calls for floating point.
@strong{Warning:} the requisite libraries may not be available.
@item -mnobitfield
+@opindex mnobitfield
Do not use the bit-field instructions. On some machines it is faster to
use shifting and masking operations. This is the default for the pc532.
@item -mbitfield
+@opindex mbitfield
Do use the bit-field instructions. This is the default for all platforms
except the pc532.
@item -mrtd
+@opindex mrtd
Use a different function-calling convention, in which functions
that take a fixed number of arguments return pop their
arguments on return with the @code{ret} instruction.
@item -mregparam
+@opindex mregparam
Use a different function-calling convention where the first two arguments
are passed in registers.
compiled with the Unix compiler.
@item -mnoregparam
+@opindex mnoregparam
Do not pass any arguments in registers. This is the default for all
targets.
@item -msb
+@opindex msb
It is OK to use the sb as an index register which is always loaded with
zero. This is the default for the pc532-netbsd target.
@item -mnosb
+@opindex mnosb
The sb register is not available for use or has not been initialized to
zero by the run time system. This is the default for all targets except
the pc532-netbsd. It is also implied whenever @samp{-mhimem} or
@samp{-fpic} is set.
@item -mhimem
+@opindex mhimem
Many ns32000 series addressing modes use displacements of up to 512MB.
If an address is above 512MB then displacements from zero can not be used.
This option causes code to be generated which can be loaded above 512MB.
This may be useful for operating systems or ROM code.
@item -mnohimem
+@opindex mnohimem
Assume code will be loaded in the first 512MB of virtual address space.
This is the default for all platforms.
@table @gcctabopt
@item -mmcu=@var{mcu}
+@opindex mmcu
Specify ATMEL AVR instruction set or MCU type.
Instruction set avr1 is for the minimal AVR core, not supported by the C
memory space (MCU types: atmega161, atmega163, atmega32, at94k).
@item -msize
+@opindex msize
Output instruction sizes to the asm file.
@item -minit-stack=@var{N}
+@opindex minit-stack
Specify the initial stack address, which may be a symbol or numeric value,
__stack is the default.
@item -mno-interrupts
+@opindex mno-interrupts
Generated code is not compatible with hardware interrupts.
Code size will be smaller.
@item -mcall-prologues
+@opindex mcall-prologues
Functions prologues/epilogues expanded as call to appropriate
subroutines. Code size will be smaller.
@item -mno-tablejump
+@opindex mno-tablejump
Do not generate tablejump insns which sometimes increase code size.
@item -mtiny-stack
+@opindex mtiny-stack
Change only the low 8 bits of the stack pointer.
@end table
@item -mhardlit
@itemx -mhardlit
@itemx -mno-hardlit
+@opindex mhardlit
+@opindex mhardlit
+@opindex mno-hardlit
Inline constants into the code stream if it can be done in two
instructions or less.
@item -mdiv
@itemx -mdiv
@itemx -mno-div
+@opindex mdiv
+@opindex mdiv
+@opindex mno-div
Use the divide instruction. (Enabled by default).
@item -mrelax-immediate
@itemx -mrelax-immediate
@itemx -mno-relax-immediate
+@opindex mrelax-immediate
+@opindex mrelax-immediate
+@opindex mno-relax-immediate
Allow arbitrary sized immediates in bit operations.
@item -mwide-bitfields
@itemx -mwide-bitfields
@itemx -mno-wide-bitfields
+@opindex mwide-bitfields
+@opindex mwide-bitfields
+@opindex mno-wide-bitfields
Always treat bitfields as int-sized.
@item -m4byte-functions
@itemx -m4byte-functions
@itemx -mno-4byte-functions
+@opindex m4byte-functions
+@opindex m4byte-functions
+@opindex mno-4byte-functions
Force all functions to be aligned to a four byte boundary.
@item -mcallgraph-data
@itemx -mcallgraph-data
@itemx -mno-callgraph-data
+@opindex mcallgraph-data
+@opindex mcallgraph-data
+@opindex mno-callgraph-data
Emit callgraph information.
@item -mslow-bytes
@itemx -mslow-bytes
@itemx -mno-slow-bytes
+@opindex mslow-bytes
+@opindex mslow-bytes
+@opindex mno-slow-bytes
Prefer word access when reading byte quantities.
@item -mlittle-endian
@itemx -mlittle-endian
@itemx -mbig-endian
+@opindex mlittle-endian
+@opindex mlittle-endian
+@opindex mbig-endian
Generate code for a little endian target.
@item -m210
@itemx -m210
@itemx -m340
+@opindex m210
+@opindex m210
+@opindex m340
Generate code for the 210 processor.
@end table
@table @gcctabopt
@item -mbig-endian
+@opindex mbig-endian
Generate code for a big endian target. This is the default for HPUX.
@item -mlittle-endian
+@opindex mlittle-endian
Generate code for a little endian target. This is the default for AIX5
and Linux.
@item -mgnu-as
@itemx -mno-gnu-as
+@opindex mgnu-as
+@opindex mno-gnu-as
Generate (or don't) code for the GNU assembler. This is the default.
@c Also, this is the default if the configure option @samp{--with-gnu-as}
@c is used.
@item -mgnu-ld
@itemx -mno-gnu-ld
+@opindex mgnu-ld
+@opindex mno-gnu-ld
Generate (or don't) code for the GNU linker. This is the default.
@c Also, this is the default if the configure option @samp{--with-gnu-ld}
@c is used.
@item -mno-pic
+@opindex mno-pic
Generate code that does not use a global pointer register. The result
is not position independent code, and violates the IA-64 ABI.
@item -mvolatile-asm-stop
@itemx -mno-volatile-asm-stop
+@opindex mvolatile-asm-stop
+@opindex mno-volatile-asm-stop
Generate (or don't) a stop bit immediately before and after volatile asm
statements.
@item -mb-step
+@opindex mb-step
Generate code that works around Itanium B step errata.
@item -mregister-names
@itemx -mno-register-names
+@opindex mregister-names
+@opindex mno-register-names
Generate (or don't) @samp{in}, @samp{loc}, and @samp{out} register names for
the stacked registers. This may make assembler output more readable.
@item -mno-sdata
@itemx -msdata
+@opindex mno-sdata
+@opindex msdata
Disable (or enable) optimizations that use the small data section. This may
be useful for working around optimizer bugs.
@item -mconstant-gp
+@opindex mconstant-gp
Generate code that uses a single constant global pointer value. This is
useful when compiling kernel code.
@item -mauto-pic
+@opindex mauto-pic
Generate code that is self-relocatable. This implies @samp{-mconstant-gp}.
This is useful when compiling firmware code.
@item -minline-divide-min-latency
+@opindex minline-divide-min-latency
Generate code for inline divides using the minimum latency algorithm.
@item -minline-divide-max-throughput
+@opindex minline-divide-max-throughput
Generate code for inline divides using the maximum throughput algorithm.
@item -mno-dwarf2-asm
@itemx -mdwarf2-asm
+@opindex mno-dwarf2-asm
+@opindex mdwarf2-asm
Don't (or do) generate assembler code for the DWARF2 line number debugging
info. This may be useful when not using the GNU assembler.
@item -mfixed-range=@var{register range}
+@opindex mfixed-range
Generate code treating the given register range as fixed registers.
A fixed register is one that the register allocator can not use. This is
useful when compiling kernel code. A register range is specified as
@table @gcctabopt
@item -mextmem
+@opindex mextmem
Link the @samp{.text}, @samp{.data}, @samp{.bss}, @samp{.strings},
@samp{.rodata}, @samp{.rodata1}, @samp{.data1} sections into external
memory, which starts at location @code{0x80000000}.
@item -mextmemory
+@opindex mextmemory
Same as the @samp{-mextmem} switch.
@item -monchip
+@opindex monchip
Link the @samp{.text} section into onchip text memory, which starts at
location @code{0x0}. Also link @samp{.data}, @samp{.bss},
@samp{.strings}, @samp{.rodata}, @samp{.rodata1}, @samp{.data1} sections
@item -mno-asm-optimize
@itemx -masm-optimize
+@opindex mno-asm-optimize
+@opindex masm-optimize
Disable (enable) passing @samp{-O} to the assembler when optimizing.
The assembler uses the @samp{-O} option to automatically parallelize
adjacent short instructions where possible.
@item -mbranch-cost=@var{n}
+@opindex mbranch-cost
Increase the internal costs of branches to @var{n}. Higher costs means
that the compiler will issue more instructions to avoid doing a branch.
The default is 2.
@item -mcond-exec=@var{n}
+@opindex mcond-exec
Specify the maximum number of conditionally executed instructions that
replace a branch. The default is 4.
@end table
@table @gcctabopt
@item -fexceptions
+@opindex fexceptions
Enable exception handling. Generates extra code needed to propagate
exceptions. For some targets, this implies GNU CC will generate frame
unwind information for all functions, which can produce significant data
use exception handling.
@item -funwind-tables
+@opindex funwind-tables
Similar to @option{-fexceptions}, except that it will just generate any needed
static data, but will not affect the generated code in any other way.
You will normally not enable this option; instead, a language processor
that needs this handling would enable it on your behalf.
@item -fpcc-struct-return
+@opindex fpcc-struct-return
Return ``short'' @code{struct} and @code{union} values in memory like
longer ones, rather than in registers. This convention is less
efficient, but it has the advantage of allowing intercallability between
that of some integer type.
@item -freg-struct-return
+@opindex freg-struct-return
Use the convention that @code{struct} and @code{union} values are
returned in registers when possible. This is more efficient for small
structures than @samp{-fpcc-struct-return}.
and we chose the more efficient register return alternative.
@item -fshort-enums
+@opindex fshort-enums
Allocate to an @code{enum} type only as many bytes as it needs for the
declared range of possible values. Specifically, the @code{enum} type
will be equivalent to the smallest integer type which has enough room.
@item -fshort-double
+@opindex fshort-double
Use the same size for @code{double} as for @code{float}.
@item -fshared-data
+@opindex fshared-data
Requests that the data and non-@code{const} variables of this
compilation be shared data rather than private data. The distinction
makes sense only on certain operating systems, where shared data is
exists in one copy per process.
@item -fno-common
+@opindex fno-common
In C, allocate even uninitialized global variables in the data section of the
object file, rather than generating them as common blocks. This has the
effect that if the same variable is declared (without @code{extern}) in
program will work on other systems which always work this way.
@item -fno-ident
+@opindex fno-ident
Ignore the @samp{#ident} directive.
@item -fno-gnu-linker
+@opindex fno-gnu-linker
Do not output global initializations (such as C++ constructors and
destructors) in the form used by the GNU linker (on systems where the GNU
linker is the standard method of handling them). Use this option when
compiler driver @command{gcc} is configured to do this automatically.
@item -finhibit-size-directive
+@opindex finhibit-size-directive
Don't output a @code{.size} assembler directive, or anything else that
would cause trouble if the function is split in the middle, and the
two halves are placed at locations far apart in memory. This option is
for anything else.
@item -fverbose-asm
+@opindex fverbose-asm
Put extra commentary information in the generated assembly code to
make it more readable. This option is generally only of use to those
who actually need to read the generated assembly code (perhaps while
files.
@item -fvolatile
+@opindex fvolatile
Consider all memory references through pointers to be volatile.
@item -fvolatile-global
+@opindex fvolatile-global
Consider all memory references to extern and global data items to
be volatile. GCC does not consider static data items to be volatile
because of this switch.
@item -fvolatile-static
+@opindex fvolatile-static
Consider all memory references to static data to be volatile.
@item -fpic
+@opindex fpic
@cindex global offset table
@cindex PIC
Generate position-independent code (PIC) suitable for use in a shared
position-independent.
@item -fPIC
+@opindex fPIC
If supported for the target machine, emit position-independent code,
suitable for dynamic linking and avoiding any limit on the size of the
global offset table. This option makes a difference on the m68k, m88k,
only on certain machines.
@item -ffixed-@var{reg}
+@opindex ffixed
Treat the register named @var{reg} as a fixed register; generated code
should never refer to it (except perhaps as a stack pointer, frame
pointer or in some other fixed role).
three-way choice.
@item -fcall-used-@var{reg}
+@opindex fcall-used
Treat the register named @var{reg} as an allocable register that is
clobbered by function calls. It may be allocated for temporaries or
variables that do not live across a call. Functions compiled this way
three-way choice.
@item -fcall-saved-@var{reg}
+@opindex fcall-saved
Treat the register named @var{reg} as an allocable register saved by
functions. It may be allocated even for temporaries or variables that
live across a call. Functions compiled this way will save and restore
three-way choice.
@item -fpack-struct
+@opindex fpack-struct
Pack all structure members together without holes. Usually you would
not want to use this option, since it makes the code suboptimal, and
the offsets of structure members won't agree with system libraries.
@item -fcheck-memory-usage
+@opindex fcheck-memory-usage
Generate extra code to check each memory access. GCC will generate
code that is suitable for a detector of bad memory accesses such as
@file{Checker}.
These calls would be similar to those done in the stubs described above.
@item -fprefix-function-name
+@opindex fprefix-function-name
Request GCC to add a prefix to the symbols generated for function names.
GCC adds a prefix to the names of functions defined as well as
functions called. Code compiled with this option and code compiled
This option is designed to be used with @samp{-fcheck-memory-usage}.
@item -finstrument-functions
+@opindex finstrument-functions
Generate instrumentation calls for entry and exit to functions. Just
after function entry and just before function exit, the following
profiling functions will be called with the address of the current
routines generate output or allocate memory).
@item -fstack-check
+@opindex fstack-check
Generate code to verify that you do not go beyond the boundary of the
stack. You should specify this flag if you are running in an
environment with multiple threads, but only rarely need to specify it in
@item -fstack-limit-register=@var{reg}
@itemx -fstack-limit-symbol=@var{sym}
@itemx -fno-stack-limit
+@opindex fstack-limit-register
+@opindex fstack-limit-symbol
+@opindex fno-stack-limit
Generate code to ensure that the stack does not grow beyond a certain value,
either the value of a register or the address of a symbol. If the stack
would grow beyond the value, a signal is raised. For most targets,
@item -fargument-alias
@itemx -fargument-noalias
@itemx -fargument-noalias-global
+@opindex fargument-alias
+@opindex fargument-noalias
+@opindex fargument-noalias-global
Specify the possible relationships among parameters and between
parameters and global data.
the language standard. You should not need to use these options yourself.
@item -fleading-underscore
+@opindex fleading-underscore
This option and its counterpart, -fno-leading-underscore, forcibly
change the way C symbols are represented in the object file. One use
is to help link with legacy assembly code.
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