-@c Copyright (C) 1988,89,92,93,94,95,96,97,1998 Free Software Foundation, Inc.
+@c Copyright (C) 1988, 89, 92-98, 1999 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
-fno-for-scope -fno-gnu-keywords -fguiding-decls -fhandle-signatures
-fhonor-std -fhuge-objects -fno-implicit-templates -finit-priority
-fno-implement-inlines -fname-mangling-version-@var{n} -fno-default-inline
--foperator-names -fno-optional-diags -frepo -fstrict-prototype
+-foperator-names -fno-optional-diags -fpermissive -frepo -fstrict-prototype
-fsquangle -ftemplate-depth-@var{n} -fthis-is-variable -fvtable-thunks
--nostdinc++
+-nostdinc++ -Wctor-dtor-privacy -Wno-deprecated -Weffc++
+-Wno-non-template-friend
+-Wnon-virtual-dtor -Wold-style-cast -Woverloaded-virtual
+-Wno-pmf-conversions -Wreorder -Wsign-promo -Wsynth
@end smallexample
@item Warning Options
@smallexample
-fsyntax-only -pedantic -pedantic-errors
-w -W -Wall -Waggregate-return -Wbad-function-cast
--Wcast-align -Wcast-qual -Wchar-subscript -Wcomment
+-Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment
-Wconversion -Werror -Wformat
-Wid-clash-@var{len} -Wimplicit -Wimplicit-int
-Wimplicit-function-declaration -Wimport
-Wlarger-than-@var{len} -Wlong-long
-Wmain -Wmissing-declarations -Wmissing-noreturn
-Wmissing-prototypes -Wmultichar -Wnested-externs -Wno-import
--Wno-non-template-friend -Wold-style-cast -Woverloaded-virtual
--Wparentheses -Wpointer-arith -Wredundant-decls -Wreorder
+-Wparentheses -Wpointer-arith -Wredundant-decls
-Wreturn-type -Wshadow -Wsign-compare -Wstrict-prototypes
--Wswitch -Wsynth -Wtraditional
+-Wswitch -Wtraditional
-Wtrigraphs -Wundef -Wuninitialized -Wunused -Wwrite-strings
-Wunknown-pragmas
@end smallexample
-fdelayed-branch -fexpensive-optimizations
-ffast-math -ffloat-store -fforce-addr -fforce-mem
-fdata-sections -ffunction-sections -fgcse
--finline-functions -fkeep-inline-functions
+-finline-functions -finline-limit-@var{n} -fkeep-inline-functions
-fno-default-inline -fno-defer-pop -fno-function-cse
-fno-inline -fno-peephole -fomit-frame-pointer -fregmove
-frerun-cse-after-loop -frerun-loop-opt -fschedule-insns
-idirafter @var{dir}
-include @var{file} -imacros @var{file}
-iprefix @var{file} -iwithprefix @var{dir}
--iwithprefixbefore @var{dir} -isystem @var{dir}
+-iwithprefixbefore @var{dir} -isystem @var{dir} -isystem-c++ @var{dir}
-M -MD -MM -MMD -MG -nostdinc -P -trigraphs
-undef -U@var{macro} -Wp,@var{option}
@end smallexample
@emph{M680x0 Options}
-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040
-m68060 -mcpu32 -m5200 -m68881 -mbitfield -mc68000 -mc68020
--mfpa -mnobitfield -mrtd -mshort -msoft-float
+-mfpa -mnobitfield -mrtd -mshort -msoft-float -mpcrel
-malign-int
@emph{VAX Options}
-mcpu= -march= -mfpe=
-mstructure-size-boundary=
-mbsd -mxopen -mno-symrename
+-mabort-on-noreturn
+-mno-sched-prolog
+-mnop-fun-dllimport -mno-nop-fun-dllimport
@emph{Thumb Options}
-mtpcs-frame -mno-tpcs-frame
-mlittle-endian -mbig-endian
-mthumb-interwork -mno-thumb-interwork
-mstructure-size-boundary=
+-mnop-fun-dllimport -mno-nop-fun-dllimport
+-mcallee-super-interworking -mno-callee-super-interworking
+-mcaller-super-interworking -mno-caller-super-interworking
@emph{MN10200 Options}
-mrelax
-mabicalls -mcpu=@var{cpu type} -membedded-data
-membedded-pic -mfp32 -mfp64 -mgas -mgp32 -mgp64
-mgpopt -mhalf-pic -mhard-float -mint64 -mips1
--mips2 -mips3 -mips4 -mlong64 -mlong-calls -mmemcpy
+-mips2 -mips3 -mips4 -mlong64 -mlong32 -mlong-calls -mmemcpy
-mmips-as -mmips-tfile -mno-abicalls
-mno-embedded-data -mno-embedded-pic
-mno-gpopt -mno-long-calls
-mno-wide-multiply -mrtd -malign-double
-mreg-alloc=@var{list} -mregparm=@var{num}
-malign-jumps=@var{num} -malign-loops=@var{num}
--malign-functions=@var{num}
+-malign-functions=@var{num} -mpreferred-stack-boundary=@var{num}
@emph{HPPA Options}
+-march=@var{architecture type}
-mbig-switch -mdisable-fpregs -mdisable-indexing
-mfast-indirect-calls -mgas -mjump-in-delay
-mlong-load-store -mno-big-switch -mno-disable-fpregs
-mno-jump-in-delay -mno-long-load-store
-mno-portable-runtime -mno-soft-float -mno-space
-mno-space-regs -msoft-float -mpa-risc-1-0
--mpa-risc-1-1 -mportable-runtime
--mschedule=@var{list} -mspace -mspace-regs
+-mpa-risc-1-1 -mpa-risc-2-0 -mportable-runtime
+-mschedule=@var{cpu type} -mspace -mspace-regs
@emph{Intel 960 Options}
-m@var{cpu type} -masm-compat -mclean-linkage
-mmangle-cpu -mcpu=@var{cpu} -mtext=@var{text section}
-mdata=@var{data section} -mrodata=@var{readonly data section}
+@emph{TMS320C3x/C4x Options}
+-mcpu=@var{cpu} -mbig -msmall -mregparm -mmemparm
+-mfast-fix -mmpyi -mbk -mti -mdp-isr-reload
+-mrpts=@var{count} -mrptb -mdb -mloop-unsigned
+-mparallel-insns -mparallel-mpy -mpreserve-float
+
@emph{V850 Options}
-mlong-calls -mno-long-calls -mep -mno-ep
-mprolog-function -mno-prolog-function -mspace
-fno-common -fno-ident -fno-gnu-linker
-fpcc-struct-return -fpic -fPIC
-freg-struct-return -fshared-data -fshort-enums
--fshort-double -fvolatile -fvolatile-global
+-fshort-double -fvolatile -fvolatile-global -fvolatile-static
-fverbose-asm -fpack-struct -fstack-check
-fargument-alias -fargument-noalias
-fargument-noalias-global
@cindex suffixes for C++ source
@cindex C++ source file suffixes
C++ source files conventionally use one of the suffixes @samp{.C},
-@samp{.cc}, @samp{cpp}, or @samp{.cxx}; preprocessed C++ files use the
-suffix @samp{.ii}. GNU CC recognizes files with these names and
-compiles them as C++ programs even if you call the compiler the same way
-as for compiling C programs (usually with the name @code{gcc}).
+@samp{.cc}, @samp{.cpp}, @samp{.c++}, @samp{.cp}, or @samp{.cxx};
+preprocessed C++ files use the suffix @samp{.ii}. GNU CC recognizes
+files with these names and compiles them as C++ programs even if you
+call the compiler the same way as for compiling C programs (usually with
+the name @code{gcc}).
@findex g++
@findex c++
or otherwise without a suffix that flags them as C++ programs.
@code{g++} is a program that calls GNU CC with the default language
set to C++, and automatically specifies linking against the C++
-library.
-@cindex @code{g++ 1.@var{xx}}
-@cindex @code{g++}, separate compiler
-@cindex @code{g++} older version
-@footnote{Prior to release 2 of the compiler,
-there was a separate @code{g++} compiler. That version was based on GNU
-CC, but not integrated with it. Versions of @code{g++} with a
-@samp{1.@var{xx}} version number---for example, @code{g++} version 1.37
-or 1.42---are much less reliable than the versions integrated with GCC
-2. Moreover, combining G++ @samp{1.@var{xx}} with a version 2 GCC will
-simply not work.} On many systems, the script @code{g++} is also
+library. On many systems, the script @code{g++} is also
installed with the name @code{c++}.
@cindex invoking @code{g++}
@findex strcmp
@findex strcpy
@findex strlen
-Don't recognize builtin functions that do not begin with `__builtin_'
+Don't recognize builtin functions that do not begin with @samp{__builtin_}
as prefix. Currently, the functions affected include @code{abort},
@code{abs}, @code{alloca}, @code{cos}, @code{exit}, @code{fabs},
@code{ffs}, @code{labs}, @code{memcmp}, @code{memcpy}, @code{sin},
libgcc} must be built with the same setting of this option.
@item -fno-implicit-templates
-Never emit code for templates which are instantiated implicitly (i.e. by
-use); only emit code for explicit instantiations. @xref{Template
-Instantiation}, for more information.
+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
+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 -finit-priority
Support @samp{__attribute__ ((init_priority (n)))} for controlling the
template <class T, class U> void foo(T t);
@end example
+Like all options that change the ABI, all C++ code, @emph{including
+libgcc} must be built with the same setting of this option.
+
@item -foperator-names
Recognize the operator name keywords @code{and}, @code{bitand},
@code{bitor}, @code{compl}, @code{not}, @code{or} and @code{xor} as
@item -fno-optional-diags
Disable diagnostics that the standard says a compiler does not need to
-issue. Currently, this means the diagnostic for a name having multiple
-meanings within a class.
+issue. Currently, the only such diagnostic issued by g++ is the one for
+a name having multiple meanings within a class.
+
+@item -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 superceded by @samp{-pedantic}, which works as it does for GNU C.
@item -frepo
Enable automatic template instantiation. This option also implies
@samp{-fno-implicit-templates}. @xref{Template Instantiation}, for more
information.
+@item -fno-rtti
+Disable generation of the information used by C++ runtime type
+identification features (@samp{dynamic_cast} and @samp{typeid}). If you
+don't use those parts of the language (or exception handling, which uses
+@samp{dynamic_cast} internally), you can save some space by using this
+flag.
+
@item -fstrict-prototype
Within an @samp{extern "C"} linkage specification, treat a function
declaration with no arguments, such as @samp{int foo ();}, as declaring
implementations store a single pointer to a @samp{thunk} function which
does any necessary adjustment and then calls the target function.
+This option also enables a heuristic for controlling emission of
+vtables; if a class has any non-inline virtual functions, the vtable
+will be emitted in the translation unit containing the first one of
+those.
+
Like all options that change the ABI, all C++ code, @emph{including
libgcc.a} must be built with the same setting of this option.
functions will have linkage like inline functions; they just won't be
inlined by default.
-@item -Wno-non-template-friend
-@xref{Warning Options,,Options to Request or Suppress Warnings}.
-@item -Wold-style-cast
-@itemx -Woverloaded-virtual
-Warnings that apply only to C++ programs. @xref{Warning
-Options,,Options to Request or Suppress Warnings}.
+@item -Wctor-dtor-privacy (C++ only)
+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)
+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)
+@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:
+
+@smallexample
+struct A @{
+ int i;
+ int j;
+ A(): j (0), i (1) @{ @}
+@};
+@end smallexample
-@item -Weffc++
-Warn about violation of some style rules from Effective C++ by Scott Myers.
+Here the compiler will warn that the member initializers for @samp{i}
+and @samp{j} will be rearranged to match the declaration order of the
+members.
+@end table
+
+The following @samp{-W@dots{}} options are not affected by @samp{-Wall}.
+
+@table @code
+@item -Weffc++ (C++ only)
+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)
+Do not warn about usage of deprecated features. @xref{Deprecated Features}.
+
+@item -Wno-non-template-friend (C++ only)
+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,
+@samp{friend foo(int)}), the C++ language specification demands that the
+friend declare or define an ordinary, nontemplate function. (Section
+14.5.3). Before g++ implemented explicit specification, unqualified-ids
+could be interpreted as a particular specialization of a templatized
+function. Because this non-conforming behavior is no longer the default
+behavior for g++, @samp{-Wnon-template-friend} allows the compiler to
+check existing code for potential trouble spots, and is on by default.
+This new compiler behavior can also be turned off with the flag
+@samp{-fguiding-decls}, which activates the older, non-specification
+compiler code, or with @samp{-Wno-non-template-friend} which keeps the
+conformant compiler code but disables the helpful warning.
+
+@item -Wold-style-cast (C++ only)
+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.
+
+@item -Woverloaded-virtual (C++ only)
+@cindex overloaded virtual fn, warning
+@cindex warning for overloaded virtual fn
+Warn when a derived class function declaration may be an error in
+defining a virtual function. In a derived class, the
+definitions of virtual functions must match the type signature of a
+virtual function declared in the base class. With this option, the
+compiler warns when you define a function with the same name as a
+virtual function, but with a type signature that does not match any
+declarations from the base class.
+
+@item -Wno-pmf-conversions (C++ only)
+Disable the diagnostic for converting a bound pointer to member function
+to a plain pointer.
+
+@item -Wsign-promo (C++ only)
+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)
+@cindex warning for synthesized methods
+@cindex synthesized methods, warning
+Warn when g++'s synthesis behavior does not match that of cfront. For
+instance:
+
+@smallexample
+struct A @{
+ operator int ();
+ A& operator = (int);
+@};
+
+main ()
+@{
+ A a,b;
+ a = b;
+@}
+@end smallexample
+
+In this example, g++ will synthesize a default @samp{A& operator =
+(const A&);}, while cfront will use the user-defined @samp{operator =}.
@end table
@node Warning Options
specify both @samp{-W} and @samp{-Wunused}.
To suppress this warning for an expression, simply cast it to void. For
-unused variables and parameters, use the @samp{unused} attribute
+unused variables, parameters and labels, use the @samp{unused} attribute
(@pxref{Variable Attributes}).
@item -Wuninitialized
you use that never return as @code{noreturn}. @xref{Function
Attributes}.
-@item -Wreorder (C++ only)
-@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:
-
-@smallexample
-struct A @{
- int i;
- int j;
- A(): j (0), i (1) @{ @}
-@};
-@end smallexample
-
-Here the compiler will warn that the member initializers for @samp{i}
-and @samp{j} will be rearranged to match the declaration order of the
-members.
-
-@item -Wtemplate-debugging
-@cindex template debugging
-When using templates in a C++ program, warn if debugging is not yet
-fully available (C++ only).
-
@item -Wunknown-pragmas
@cindex warning for unknown pragmas
@cindex unknown pragmas, warning
@item
A @code{switch} statement has an operand of type @code{long}.
+
+@item
+A non-@code{static} function declaration follows a @code{static} one.
+This construct is not accepted by some traditional C compilers.
@end itemize
@item -Wundef
@item -Wnested-externs
Warn if an @code{extern} declaration is encountered within an function.
-@item -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,
-@samp{friend foo(int)}), the C++ language specification demands that the
-friend declare or define an ordinary, nontemplate function. (Section
-14.5.3). Before g++ implemented explicit specification, unqualified-ids
-could be interpreted as a particular specialization of a templatized
-function. Because this non-conforming behavior is no longer the default
-behavior for g++, @samp{-Wnon-template-friend} allows the compiler to
-check existing code for potential trouble spots, and is on by default.
-This new compiler behavior can also be turned off with the flag
-@samp{-fguiding-decls}, which activates the older, non-specification
-compiler code, or with @samp{-Wno-non-template-friend} which keeps the
-conformant compiler code but disables the helpful warning.
-
@item -Winline
Warn if a function can not be inlined, and either it was declared as inline,
or else the @samp{-finline-functions} option was given.
-@item -Wold-style-cast
-Warn if an old-style (C-style) cast is used within a program.
-
-@item -Woverloaded-virtual
-@cindex overloaded virtual fn, warning
-@cindex warning for overloaded virtual fn
-Warn when a derived class function declaration may be an error in
-defining a virtual function (C++ only). In a derived class, the
-definitions of virtual functions must match the type signature of a
-virtual function declared in the base class. With this option, the
-compiler warns when you define a function with the same name as a
-virtual function, but with a type signature that does not match any
-declarations from the base class.
-
-@item -Wsynth (C++ only)
-@cindex warning for synthesized methods
-@cindex synthesized methods, warning
-Warn when g++'s synthesis behavior does not match that of cfront. For
-instance:
-
-@smallexample
-struct A @{
- operator int ();
- A& operator = (int);
-@};
-
-main ()
-@{
- A a,b;
- a = b;
-@}
-@end smallexample
-
-In this example, g++ will synthesize a default @samp{A& operator =
-(const A&);}, while cfront will use the user-defined @samp{operator =}.
-
@item -Wlong-long
Warn if @samp{long long} type is used. This is default. To inhibit
the warning messages, use @samp{-Wno-long-long}. Flags
@item D
Dump all macro definitions, at the end of preprocessing, in addition to
normal output.
-@item y
-Dump debugging information during parsing, to standard error.
@item r
Dump after RTL generation, to @file{@var{file}.rtl}.
-@item x
-Just generate RTL for a function instead of compiling it. Usually used
-with @samp{r}.
@item j
Dump after first jump optimization, to @file{@var{file}.jump}.
-@item s
-Dump after CSE (including the jump optimization that sometimes
-follows CSE), to @file{@var{file}.cse}.
@item F
Dump after purging ADDRESSOF, to @file{@var{file}.addressof}.
@item f
@item t
Dump after the second CSE pass (including the jump optimization that
sometimes follows CSE), to @file{@var{file}.cse2}.
-@item x
-Just generate RTL for a function instead of compiling it. Usually used
-with @samp{r}.
@item a
Produce all the dumps listed above.
@item m
standard error.
@item p
Annotate the assembler output with a comment indicating which
-pattern and alternative was used.
+pattern and alternative was used. The length of each instruction is
+also printed.
+@item x
+Just generate RTL for a function instead of compiling it. Usually used
+with @samp{r}.
@item y
Dump debugging information during parsing, to standard error.
@item A
declared @code{static}, then the function is normally not output as
assembler code in its own right.
+@item -finline-limit-@var{n}
+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
+definition in c++). @var{n} is the size of functions that can be inlined in
+number of pseudo instructions (not counting parameter handling). The default
+value of n is 10000. Increasing this value can result in more inlined code at
+the cost of compilation time and memory consumption. Decreasing usually makes
+the compilation faster and less code will be inlined (which presumably
+means slower programs). This option is particularly useful for programs that
+use inlining heavily such as those based on recursive templates with c++.
+
+@emph{Note:} pseudo instruction represents, in this particular context, an
+abstract measurement of function's size. In no way, it represents a count
+of assembly instructions and as such its exact meaning might change from one
+release to an another.
+
@item -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
Perform a number of minor optimizations that are relatively expensive.
@item -foptimize-register-moves
-@item -fregmove
+@itemx -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
registers and where memory load instructions take more than one cycle.
@item -ffunction-sections
-@item -fdata-sections
+@itemx -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
they have helped determine the efficacy of various
approaches to improving loop optimizations.
-Please let us (@code{egcs@@cygnus.com} and @code{fortran@@gnu.org})
+Please let us (@code{egcs@@egcs.cygnus.com} and @code{fortran@@gnu.org})
know how use of these options affects
the performance of your production code.
We're very interested in code that runs @emph{slower}
* H8/300 Options::
* SH Options::
* System V Options::
+* TMS320C3x/C4x Options::
* V850 Options::
* ARC Options::
* NS32K Options::
align structures containing the above types differently than
most published application binary interface specifications for the m68k.
+@item -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
+not presently supported with -mpcrel, though this could be supported for
+68020 and higher processors.
+
@end table
@node VAX Options
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},
-@samp{f930}, @samp{f934}, @samp{sparclet}, @samp{tsc701}, @samp{v9}, and
-@samp{ultrasparc}.
+@samp{hypersparc}, @samp{sparclite86x}, @samp{f930}, @samp{f934},
+@samp{sparclet}, @samp{tsc701}, @samp{v9}, and @samp{ultrasparc}.
Default instruction scheduling parameters are used for values that select
an architecture and not an implementation. These are @samp{v7}, @samp{v8},
@smallexample
v7: cypress
- v8: supersparc
- sparclite: f930, f934
+ v8: supersparc, hypersparc
+ sparclite: f930, f934, sparclite86x
sparclet: tsc701
v9: ultrasparc
@end smallexample
The same values for @samp{-mcpu=}@var{cpu_type} are used for
@samp{-mtune=}@*@var{cpu_type}, though the only useful values are those that
select a particular cpu implementation: @samp{cypress}, @samp{supersparc},
-@samp{f930}, @samp{f934}, @samp{tsc701}, @samp{ultrasparc}.
+@samp{hypersparc}, @samp{f930}, @samp{f934}, @samp{sparclite86x},
+@samp{tsc701}, @samp{ultrasparc}.
@item -malign-loops=@var{num}
Align loops to a 2 raised to a @var{num} byte boundary. If
this can't be done directly in cross-compilation. You must make your
own arrangements to provide suitable library functions for
cross-compilation.
+
+@item -mno-multm
+@kindex -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
@node ARM Options
assembly code. Permissable names are: arm2, arm250, arm3, arm6, arm60,
arm600, arm610, arm620, arm7, arm7m, arm7d, arm7dm, arm7di, arm7dmi,
arm70, arm700, arm700i, arm710, arm710c, arm7100, arm7500, arm7500fe,
-arm7tdmi, arm8, strongarm, strongarm110
+arm7tdmi, arm8, strongarm, strongarm110, strongarm1100, arm8, arm810,
+arm9, arm920, arm920t, arm9tdmi.
+
+@itemx -mtune=<name>
+@kindex -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
+tune the performance of the code as if the target were of the type
+specified in this option, but still choosing the instructions that it
+will generate based on the cpu specified by a @samp{-mcpu=} option.
+For some arm implementations better performance can be obtained by using
+this option.
@item -march=<name>
@kindex -march=
name to determine what kind of instructions it can use when generating
assembly code. This option can be used in conjunction with or instead
of the @samp{-mcpu=} option. Permissable names are: armv2, armv2a,
-armv3, armv3m, armv4, armv4t
+armv3, armv3m, armv4, armv4t, armv5.
@item -mfpe=<number>
+@itemx -mfp=<number>
@kindex -mfpe=
+@kindex -mfp=
This specifes the version of the floating point emulation available on
-the target. Permissable values are 2 and 3.
+the target. Permissable values are 2 and 3. @samp{-mfp=} is a synonym
+for @samp{-mfpe=} to support older versions of GCC.
@item -mstructure-size-boundary=<n>
@kindex -mstructure-size-boundary
using structures or unions. Programmers are encouraged to use the 32
value as future versions of the toolchain may default to this value.
+@item -mabort-on-noreturn
+@kindex -mabort-on-noreturn
+@kindex -mnoabort-on-noreturn
+Generate a call to the function abort at the end of a noreturn function.
+It will be executed if the function tries to return.
+
+@item -mnop-fun-dllimport
+@kindex -mnop-fun-dllimport
+Disable the support for the @emph{dllimport} attribute.
+
@end table
@node Thumb Options
using structures or unions. Programmers are encouraged to use the 32
value as future versions of the toolchain may default to this value.
+@item -mnop-fun-dllimport
+@kindex -mnop-fun-dllimport
+Disable the support for the @emph{dllimport} attribute.
+
+@item -mcallee-super-interworking
+@kindex -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
+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
+of executing a funciton pointer if this option is enabled.
+
@end table
@node MN10200 Options
instruction scheduling parameters for machine type @var{cpu_type}.
Supported values for @var{cpu_type} are @samp{rs6000}, @samp{rios1},
@samp{rios2}, @samp{rsc}, @samp{601}, @samp{602}, @samp{603},
-@samp{603e}, @samp{604}, @samp{604e}, @samp{620}, @samp{power},
-@samp{power2}, @samp{powerpc}, @samp{403}, @samp{505}, @samp{801},
-@samp{821}, @samp{823}, and @samp{860} and @samp{common}.
-@samp{-mcpu=power}, @samp{-mcpu=power2}, and @samp{-mcpu=powerpc}
-specify generic POWER, POWER2 and pure PowerPC (i.e., not MPC601)
-architecture machine types, with an appropriate, generic processor model
-assumed for scheduling purposes.@refill
+@samp{603e}, @samp{604}, @samp{604e}, @samp{620}, @samp{740},
+@samp{750}, @samp{power}, @samp{power2}, @samp{powerpc}, @samp{403},
+@samp{505}, @samp{801}, @samp{821}, @samp{823}, and @samp{860} and
+@samp{common}. @samp{-mcpu=power}, @samp{-mcpu=power2}, and
+@samp{-mcpu=powerpc} specify generic POWER, POWER2 and pure PowerPC
+(i.e., not MPC601) architecture machine types, with an appropriate,
+generic processor model assumed for scheduling purposes.@refill
@c overfull hbox here --bob 22 jul96
@c original text between ignore ... end ignore
instructions are generated by default on POWER systems, and not
generated on PowerPC systems. Do not use @samp{-mmultiple} on little
endian PowerPC systems, since those instructions do not work when the
-processor is in little endian mode.
+processor is in little endian mode. The exceptions are PPC740 and
+PPC750 which permit the instructions usage in little endian mode.
@item -mstring
@itemx -mno-string
@kindex -mstring
-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 POWER systems, and not
-generated on PowerPC systems. Do not use @samp{-mstring} on little endian
-PowerPC systems, since those instructions do not work when the processor is in
-little endian mode.
+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
+POWER systems, and not generated on PowerPC systems. Do not use
+@samp{-mstring} on little endian PowerPC systems, since those
+instructions do not work when the processor is in little endian mode.
+The exceptions are PPC740 and PPC750 which permit the instructions
+usage in little endian mode.
@item -mupdate
@itemx -mno-update
@itemx -mno-regnames
On System V.4 and embedded PowerPC systems do (do not) emit register
names in the assembly language output using symbolic forms.
+
@end table
+
@node RT Options
@subsection IBM RT Options
@cindex RT options
@item -mcpu=@var{cpu type}
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{r4000}, @samp{r4400}, @samp{r4600}, and @samp{r6000}. While picking a
-specific @var{cpu type} will schedule things appropriately for that
-particular chip, the compiler will not generate any code that does not
-meet level 1 of the MIPS ISA (instruction set architecture) without
-the @samp{-mips2} or @samp{-mips3} switches being used.
+@samp{r3900}, @samp{r4000}, @samp{r4100}, @samp{r4300}, @samp{r4400},
+@samp{r4600}, @samp{r4650}, @samp{r5000}, @samp{r6000}, @samp{r8000},
+and @samp{orion}. Additionally, the @samp{r2000}, @samp{r3000},
+@samp{r4000}, @samp{r5000}, and @samp{r6000} can be abbreviated as
+@samp{r2k} (or @samp{r2K}), @samp{r3k}, etc. While picking a specific
+@var{cpu type} will schedule things appropriately for that particular
+chip, the compiler will not generate any code that does not meet level 1
+of the MIPS ISA (instruction set architecture) without a @samp{-mipsX}
+or @samp{-mabi} switch being used.
@item -mips1
Issue instructions from level 1 of the MIPS ISA. This is the default.
@item -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.
-This option does not change the sizes of any of the C data types.
@item -mips4
-Issue instructions from level 4 of the MIPS ISA. @samp{r8000} is the
-default @var{cpu type} at this ISA level.
+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
Assume that 32 32-bit floating point registers are available. This is
the default when the @samp{-mips3} option is used.
@item -mint64
-Types long, int, and pointer are 64 bits. This works only if @samp{-mips3}
-is also specified.
+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
-Types long and pointer are 64 bits, and type int is 32 bits.
-This works only if @samp{-mips3} is also specified.
+Force long types to be 64 bits wide. See @samp{-mlong32} for an
+explanation of the default, and the width of pointers.
-@itemx -mabi=32
+@item -mlong32
+Force long, int, and pointer types to be 32 bits wide.
+
+If none of @samp{-mlong32}, @samp{-mlong64}, or @samp{-mint64} are set,
+the size of ints, longs, and pointers depends on the ABI and ISA choosen.
+For @samp{-mabi=32}, and @samp{-mabi=n32}, ints and longs are 32 bits
+wide. For @samp{-mabi=64}, ints are 32 bits, and longs are 64 bits wide.
+For @samp{-mabi=eabi} and either @samp{-mips1} or @samp{-mips2}, ints
+and longs are 32 bits wide. For @samp{-mabi=eabi} and higher ISAs, ints
+are 32 bits, and longs are 64 bits wide. The width of pointer types is
+the smaller of the width of longs or the width of general purpose
+registers (which in turn depends on the ISA).
+
+@item -mabi=32
+@itemx -mabi=o64
@itemx -mabi=n32
@itemx -mabi=64
@itemx -mabi=eabi
-Generate code for the indicated ABI.
+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
+@samp{-mips2}, the default ABI is @samp{32}; otherwise, the default ABI
+is @samp{64}.
@item -mmips-as
Generate code for the MIPS assembler, and invoke @file{mips-tfile} to
Turns on @samp{-msingle-float}, @samp{-mmad}, and, at least for now,
@samp{-mcpu=r4650}.
+@item -mips16
+@itemx -mno-mips16
+Enable 16-bit instructions.
+
+@item -mentry
+Use the entry and exit pseudo ops. This option can only be used with
+@samp{-mips16}.
+
@item -EL
Compile code for the processor in little endian mode.
The requisite libraries are assumed to exist.
@table @code
@item -mcpu=@var{cpu type}
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{pentium}), @samp{pentium}, @samp{i686}
-(@samp{pentiumpro}) and @samp{pentiumpro}. While picking a specific
-@var{cpu type} will schedule things appropriately for that particular
-chip, the compiler will not generate any code that does not run on the
-i386 without the @samp{-march=@var{cpu type}} option being used.
+instructions. The choices for @var{cpu type} are:
+
+@multitable @columnfractions .20 .20 .20 .20
+@item @samp{i386} @tab @samp{i486} @tab @samp{i586} @tab @samp{i686}
+@item @samp{pentium} @tab @samp{pentiumpro} @tab @samp{k6}
+@end multitable
+
+While picking a specific @var{cpu type} will schedule things appropriately
+for that particular chip, the compiler will not generate any code that
+does not run on the i386 without the @samp{-march=@var{cpu type}} option
+being used. @samp{i586} is equivalent to @samp{pentium} and @samp{i686}
+is equivalent to @samp{pentiumpro}. @samp{k6} is the AMD chip as
+opposed to the Intel ones.
@item -march=@var{cpu type}
Generate instructions for the machine type @var{cpu type}. The choices
-for @var{cpu type} are: @samp{i386}, @samp{i486}, @samp{pentium}, and
-@samp{pentiumpro}. Specifying @samp{-march=@var{cpu type}} implies
-@samp{-mcpu=@var{cpu type}}.
+for @var{cpu type} are the same as for @samp{-mcpu}. Moreover,
+specifying @samp{-march=@var{cpu type}} implies @samp{-mcpu=@var{cpu type}}.
@item -m386
@itemx -m486
@itemx -mpentium
@itemx -mpentiumpro
Synonyms for -mcpu=i386, -mcpu=i486, -mcpu=pentium, and -mcpu=pentiumpro
-respectively.
+respectively. These synonyms are deprecated.
@item -mieee-fp
@itemx -mno-ieee-fp
You can specify that an individual function is called with this calling
sequence with the function attribute @samp{stdcall}. You can also
override the @samp{-mrtd} option by using the function attribute
-@samp{cdecl}. @xref{Function Attributes}
+@samp{cdecl}. @xref{Function Attributes}.
@strong{Warning:} this calling convention is incompatible with the one
normally used on Unix, so you cannot use it if you need to call
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
-function by using the function attribute @samp{regparm}. @xref{Function Attributes}
+function by using the function attribute @samp{regparm}.
+@xref{Function Attributes}.
@strong{Warning:} if you use this switch, and
@var{num} is nonzero, then you must build all modules with the same
Align the start of functions to a 2 raised to @var{num} byte boundary.
If @samp{-malign-functions} is not specified, the default is 2 if optimizing
for a 386, and 4 if optimizing for a 486.
+
+@item -mpreferred-stack-boundary=@var{num}
+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).
+
+The stack is required to be aligned on a 4 byte boundary. On Pentium
+and PentiumPro, @code{double} and @code{long double} values should be
+aligned to an 8 byte boundary (see @samp{-malign-double}) or suffer
+significant run time performance penalties. On Pentium III, the
+Streaming SIMD Extention (SSE) data type @code{__m128} suffers similar
+penalties if it is not 16 byte aligned.
+
+To ensure proper alignment of this values on the stack, the stack boundary
+must be as aligned as that required by any value stored on the stack.
+Further, every function must be generated such that it keeps the stack
+aligned. Thus calling a function compiled with a higher preferred
+stack boundary from a function compiled with a lower preferred stack
+boundary will most likely misalign the stack. It is recommended that
+libraries that use callbacks always use the default setting.
+
+This extra alignment does consume extra stack space. Code that is sensitive
+to stack space usage, such as embedded systems and operating system kernels,
+may want to reduce the preferred alignment to
+@samp{-mpreferred-stack-boundary=2}.
@end table
@node HPPA Options
These @samp{-m} options are defined for the HPPA family of computers:
@table @code
-@item -mpa-risc-1-0
-Generate code for a PA 1.0 processor.
+@item -march=@var{architecture type}
+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
+@file{/usr/lib/sched.models} on an HP-UX system to determine the proper
+architecture option for your machine. Code compiled for lower numbered
+architectures will run on higher numbered architectures, but not the
+other way around.
+
+PA 2.0 support currently requires gas snapshot 19990413 or later. The
+next release of binutils (current is 2.9.1) will probably contain PA 2.0
+support.
-@item -mpa-risc-1-1
-Generate code for a PA 1.1 processor.
+@item -mpa-risc-1-0
+@itemx -mpa-risc-1-1
+@itemx -mpa-risc-2-0
+Synonyms for -march=1.0, -march=1.1, and -march=2.0 respectively.
@item -mbig-switch
Generate code suitable for big switch tables. Use this option only if
@item -mschedule=@var{cpu type}
Schedule code according to the constraints for the machine type
-@var{cpu type}. The choices for @var{cpu type} are @samp{700} for
-7@var{n}0 machines, @samp{7100} for 7@var{n}5 machines, and @samp{7100LC}
-for 7@var{n}2 machines. @samp{7100} is the default for @var{cpu type}.
-
-Note the @samp{7100LC} scheduling information is incomplete and using
-@samp{7100LC} often leads to bad schedules. For now it's probably best
-to use @samp{7100} instead of @samp{7100LC} for the 7@var{n}2 machines.
+@var{cpu type}. The choices for @var{cpu type} are @samp{700}
+@samp{7100}, @samp{7100LC}, @samp{7200}, and @samp{8000}. Refer to
+@file{/usr/lib/sched.models} on an HP-UX system to determine the
+proper scheduling option for your machine.
@item -mlinker-opt
Enable the optimization pass in the HPUX linker. Note this makes symbolic
@item -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
+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
+no 128-bit @samp{long double} support in @samp{fp-bit.c} yet. So it
+is only useful for people using soft-float targets. Otherwise, we
+should recommend against use of it.
+
@end table
@node DEC Alpha Options
@item -mc300
Produce code for a C300 Clipper processor. This is the default.
-@itemx -mc400
+@item -mc400
Produce code for a C400 Clipper processor i.e. use floating point
registers f8..f15.
@end table
@c the generic assembler that comes with Solaris takes just -Ym.
@end table
+@node TMS320C3x/C4x Options
+@subsection TMS320C3x/C4x Options
+@cindex TMS320C3x/C4x Options
+
+These @samp{-m} options are defined for TMS320C3x/C4x implementations:
+
+@table @code
+
+@item -mcpu=@var{cpu_type}
+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
+@samp{c44}. The default is @samp{c40} to generate code for the
+TMS320C40.
+
+@item -mbig-memory
+@item -mbig
+@itemx -msmall-memory
+@itemx -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
+containing the .bss and .data program sections. The big memory model is
+the default and requires reloading of the DP register for every direct
+memory access.
+
+@item -mbk
+@itemx -mno-bk
+Allow (disallow) allocation of general integer operands into the block
+count register BK.
+
+@item -mdb
+@itemx -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
+iteration count on the C3x is 2^23 + 1 (but who iterates loops more than
+2^23 times on the C3x?). Note that GCC will try to reverse a loop so
+that it can utilise the decrement and branch instruction, but will give
+up if there is more than one memory reference in the loop. Thus a loop
+where the loop counter is decremented can generate slightly more
+efficient code, in cases where the RPTB instruction cannot be utilised.
+
+@item -mdp-isr-reload
+@itemx -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
+violated the small memory model by modifying the DP register, say within
+an object library.
+
+@item -mmpyi
+@itemx -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
+using shifts and adds. If the -mmpyi option is not specified for the C3x,
+then squaring operations are performed inline instead of a library call.
+
+@item -mfast-fix
+@itemx -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
+floating point number is negative, the result will be incorrectly
+truncated an additional code is necessary to detect and correct this
+case. This option can be used to disable generation of the additional
+code required to correct the result.
+
+@item -mrptb
+@itemx -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
+boundaries. There is no advantage having nested RPTB loops due to the
+overhead required to save and restore the RC, RS, and RE registers.
+This is enabled by default with -O2.
+
+@item -mrpts=@var{count}
+@itemx -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
+emit a RPTS instruction instead of a RPTB. If no value is specified,
+then a RPTS will be emitted even if the loop count cannot be determined
+at compile time. Note that the repeated instruction following RPTS does
+not have to be reloaded from memory each iteration, thus freeing up the
+CPU buses for oeprands. However, since interrupts are blocked by this
+instruction, it is disabled by default.
+
+@item -mloop-unsigned
+@itemx -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
+there is a possibility than the 2^31 + 1 maximum iteration count may be
+exceeded. This switch allows an unsigned iteration count.
+
+@item -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
+rather than in floating point registers.
+
+@item -mregparm
+@itemx -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
+Allow the generation of parallel instructions. This is enabled by
+default with -O2.
+
+@item -mparallel-mpy
+@itemx -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
+of large functions.
+
+@end table
+
@node V850 Options
@subsection V850 Options
@cindex V850 Options
All variants support @samp{-mcpu=base}, this is the default.
@item -mtext=@var{text section}
-@item -mdata=@var{data section}
-@item -mrodata=@var{readonly data section}
+@itemx -mdata=@var{data section}
+@itemx -mrodata=@var{readonly data section}
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.
-@xref{Variable Attributes}
+@xref{Variable Attributes}.
@end table
@item -fvolatile-global
Consider all memory references to extern and global data items to
-be volatile.
+be volatile. GNU CC does not consider static data items to be volatile
+because of this switch.
+
+@item -fvolatile-static
+Consider all memory references to static data to be volatile.
@item -fpic
@cindex global offset table
code that is suitable for a detector of bad memory accesses such as
@file{Checker}.
-You must also specify this option when you compile functions you call that
-have side effects. If you do not, you may get erroneous messages from
-the detector. Normally, you should compile all your code with this option.
+Normally, you should compile all, or none, of your code with this option.
+
+If you do mix code compiled with and without this option,
+you must ensure that all code that has side effects
+and that is called by code compiled with this option
+is, itself, compiled with this option.
+If you do not, you might get erroneous messages from the detector.
+
If you use functions from a library that have side-effects (such as
-@code{read}), you may not be able to recompile the library and
+@code{read}), you might not be able to recompile the library and
specify this option. In that case, you can enable the
@samp{-fprefix-function-name} option, which requests GNU CC to encapsulate
your code and make other functions look as if they were compiled with
@samp{-fcheck-memory-usage}. This is done by calling ``stubs'',
which are provided by the detector. If you cannot find or build
-stubs for every function you call, you may have to specify
+stubs for every function you call, you might have to specify
@samp{-fcheck-memory-usage} without @samp{-fprefix-function-name}.
If you specify this option, you can not use the @code{asm} or
Request GNU CC to add a prefix to the symbols generated for function names.
GNU CC adds a prefix to the names of functions defined as well as
functions called. Code compiled with this option and code compiled
-without the option can't be linked together, unless or stubs are used.
+without the option can't be linked together, unless stubs are used.
If you compile the following code with @samp{-fprefix-function-name}
@example
foo (int a)
@{
return bar (a + 5);
-
@}
@end example
@end ifset
@table @code
+@item LANG
+@itemx LC_CTYPE
+@c @itemx LC_COLLATE
+@itemx LC_MESSAGES
+@c @itemx LC_MONETARY
+@c @itemx LC_NUMERIC
+@c @itemx LC_TIME
+@itemx LC_ALL
+@findex LANG
+@findex LC_CTYPE
+@c @findex LC_COLLATE
+@findex LC_MESSAGES
+@c @findex LC_MONETARY
+@c @findex LC_NUMERIC
+@c @findex LC_TIME
+@findex LC_ALL
+@cindex locale
+These environment variables control the way that GNU CC uses
+localization information that allow GNU CC to work with different
+national conventions. GNU CC inspects the locale categories
+@code{LC_CTYPE} and @code{LC_MESSAGES} if it has been configured to do
+so. These locale categories can be set to any value supported by your
+installation. A typical value is @samp{en_UK} for English in the United
+Kingdom.
+
+The @code{LC_CTYPE} environment variable specifies character
+classification. GNU CC uses it to determine the character boundaries in
+a string; this is needed for some multibyte encodings that contain quote
+and escape characters that would otherwise be interpreted as a string
+end or escape.
+
+The @code{LC_MESSAGES} environment variable specifies the language to
+use in diagnostic messages.
+
+If the @code{LC_ALL} environment variable is set, it overrides the value
+of @code{LC_CTYPE} and @code{LC_MESSAGES}; otherwise, @code{LC_CTYPE}
+and @code{LC_MESSAGES} default to the value of the @code{LANG}
+environment variable. If none of these variables are set, GNU CC
+defaults to traditional C English behavior.
+
@item TMPDIR
@findex TMPDIR
If @code{TMPDIR} is set, it specifies the directory to use for temporary
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