-@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.
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
@smallexample
--c -S -E -o @var{file} -pipe -v -x @var{language}
+-c -S -E -o @var{file} -pipe -v --help -x @var{language}
@end smallexample
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@smallexample
--ansi -fallow-single-precision -fcond-mismatch -fno-asm
+-ansi -flang-isoc9x -fallow-single-precision -fcond-mismatch -fno-asm
-fno-builtin -ffreestanding -fhosted -fsigned-bitfields -fsigned-char
-funsigned-bitfields -funsigned-char -fwritable-strings
-traditional -traditional-cpp -trigraphs
@item C++ Language Options
@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@smallexample
--fall-virtual -fdollars-in-identifiers -felide-constructors
--fenum-int-equiv -fexternal-templates -ffor-scope
--fno-for-scope -fhandle-signatures -fmemoize-lookups
--fname-mangling-version-@var{n} -fno-default-inline
--fno-gnu-keywords -fnonnull-objects -fguiding-decls
--foperator-names -fstrict-prototype -fthis-is-variable
--ftemplate-depth-@var{n} -nostdinc++ -traditional +e@var{n}
+-fno-access-control -fcheck-new -fconserve-space -fdollars-in-identifiers
+-fno-elide-constructors -fexternal-templates -ffor-scope
+-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 -fpermissive -frepo -fstrict-prototype
+-fsquangle -ftemplate-depth-@var{n} -fthis-is-variable -fvtable-thunks
+-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-declarations -Wimport -Winline
--Wlarger-than-@var{len} -Wmain -Wmissing-declarations
--Wmissing-prototypes -Wnested-externs -Wno-import
--Wold-style-cast -Woverloaded-virtual -Wparentheses
--Wpointer-arith -Wredundant-decls -Wreorder -Wreturn-type
--Wshadow -Wsign-compare -Wstrict-prototypes -Wswitch
--Wsynth -Wtemplate-debugging -Wtraditional -Wtrigraphs
--Wundef -Wuninitialized -Wunused -Wwrite-strings
+-Wimplicit-function-declaration -Wimport
+-Werror-implicit-function-declaration -Winline
+-Wlarger-than-@var{len} -Wlong-long
+-Wmain -Wmissing-declarations -Wmissing-noreturn
+-Wmissing-prototypes -Wmultichar -Wnested-externs -Wno-import
+-Wparentheses -Wpointer-arith -Wredundant-decls
+-Wreturn-type -Wshadow -Wsign-compare -Wstrict-prototypes
+-Wswitch -Wtraditional
+-Wtrigraphs -Wundef -Wuninitialized -Wunused -Wwrite-strings
-Wunknown-pragmas
@end smallexample
@item Debugging Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
@smallexample
--a -ax -d@var{letters} -fpretend-float
+-a -ax -d@var{letters} -fdump-unnumbered -fpretend-float
-fprofile-arcs -ftest-coverage
-g -g@var{level} -gcoff -gdwarf -gdwarf-1 -gdwarf-1+ -gdwarf-2
-ggdb -gstabs -gstabs+ -gxcoff -gxcoff+
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
@smallexample
--fbranch-probabilities
+-fbranch-probabilities -foptimize-register-moves
-fcaller-saves -fcse-follow-jumps -fcse-skip-blocks
-fdelayed-branch -fexpensive-optimizations
-ffast-math -ffloat-store -fforce-addr -fforce-mem
--ffunction-sections -finline-functions
--fkeep-inline-functions -fno-default-inline
--fno-defer-pop -fno-function-cse
+-fdata-sections -ffunction-sections -fgcse
+-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
-fschedule-insns2 -fstrength-reduce -fthread-jumps
-funroll-all-loops -funroll-loops
--fmove-all-movables -freduce-all-givs
+-fmove-all-movables -freduce-all-givs -fstrict-aliasing
-O -O0 -O1 -O2 -O3 -Os
@end smallexample
-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
@emph{MN10300 Options}
-mmult-bug
-mno-mult-bug
+-mrelax
@emph{M32R/D Options}
-mcode-model=@var{model type} -msdata=@var{sdata type}
-mpowerpc-gfxopt -mno-powerpc-gfxopt
-mnew-mnemonics -mno-new-mnemonics
-mfull-toc -mminimal-toc -mno-fop-in-toc -mno-sum-in-toc
--mxl-call -mno-xl-call -mthreads -mpe
+-maix64 -maix32 -mxl-call -mno-xl-call -mthreads -mpe
-msoft-float -mhard-float -mmultiple -mno-multiple
-mstring -mno-string -mupdate -mno-update
-mfused-madd -mno-fused-madd -mbit-align -mno-bit-align
-mstrict-align -mno-strict-align -mrelocatable
-mno-relocatable -mrelocatable-lib -mno-relocatable-lib
--mtoc -mno-toc -mtraceback -mno-traceback
--mlittle -mlittle-endian -mbig -mbig-endian
+-mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian
-mcall-aix -mcall-sysv -mprototype -mno-prototype
--msim -mmvme -mads -myellowknife -memb
--msdata -msdata=@var{opt} -G @var{num}
+-msim -mmvme -mads -myellowknife -memb -msdata
+-msdata=@var{opt} -G @var{num}
@emph{RT Options}
-mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs
-mabicalls -mcpu=@var{cpu type} -membedded-data
-membedded-pic -mfp32 -mfp64 -mgas -mgp32 -mgp64
-mgpopt -mhalf-pic -mhard-float -mint64 -mips1
--mips2 -mips3 -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
-mrnames -msoft-float
-m4650 -msingle-float -mmad
-mstats -EL -EB -G @var{num} -nocpp
+-mabi=32 -mabi=n32 -mabi=64 -mabi=eabi
@emph{i386 Options}
-mcpu=@var{cpu type}
-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
-mrelax -mh -ms -mint32 -malign-300
@emph{SH Options}
--m1 -m2 -m3 -m3e -mb -ml -mrelax
+-m1 -m2 -m3 -m3e -mb -ml -mdalign -mrelax
@emph{System V Options}
-Qy -Qn -YP,@var{paths} -Ym,@var{dir}
+@emph{ARC Options}
+-EB -EL
+-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
-mtda=@var{n} -msda=@var{n} -mzda=@var{n}
-mv850 -mbig-switch
+
+@emph{NS32K Options}
+-m32032 -m32332 -m32532 -m32081 -m32381 -mmult-add -mnomult-add
+-msoft-float -mrtd -mnortd -mregparam -mnoregparam -msb -mnosb
+-mbitfield -mnobitfield -mhimem -mnohimem
@end smallexample
@item Code Generation Options
-fno-common -fno-ident -fno-gnu-linker
-fpcc-struct-return -fpic -fPIC
-freg-struct-return -fshared-data -fshort-enums
--fshort-double -fvolatile -fvolatile-global
--fverbose-asm -fpack-struct -fstack-check +e0 +e1
+-fshort-double -fvolatile -fvolatile-global -fvolatile-static
+-fverbose-asm -fpack-struct -fstack-check
-fargument-alias -fargument-noalias
-fargument-noalias-global
+-fleading-underscore
@end smallexample
@end table
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
+Print (on the standard output) a description of the command line options
+understood by @code{gcc}. If the @code{-v} option is also specified
+then @code{--help} will also be passed on to the various processes
+invoked by @code{gcc}, so that they can display the command line options
+they accept. If the @code{-W} option is also specified then command
+line options which have no documentation associated with them will also
+be displayed.
@end table
@node Invoking G++
@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++}
The functions @code{alloca}, @code{abort}, @code{exit}, and
@code{_exit} are not builtin functions when @samp{-ansi} is used.
+@item -flang-isoc9x
+Enable support for features found in the C9X standard. In particular,
+enable support for the C9X @code{restrict} keyword.
+
+Even when this option is not specified, you can still use some C9X
+features in so far as they do not conflict with previous C standards.
+For example, you may use @code{__restrict__} even when -flang-isoc9x
+is not specified.
+
@item -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
@findex strcmp
@findex strcpy
@findex strlen
-Don't recognize builtin functions that do not begin with two leading
-underscores. Currently, the functions affected include @code{abort},
+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},
@code{sqrt}, @code{strcmp}, @code{strcpy}, and @code{strlen}.
literal characters @samp{x} and @samp{a} respectively. Without
@w{@samp{-traditional}}, @samp{\x} is a prefix for the hexadecimal
representation of a character, and @samp{\a} produces a bell.
-
-@item
-In C++ programs, assignment to @code{this} is permitted with
-@samp{-traditional}. (The option @samp{-fthis-is-variable} also has
-this effect.)
@end itemize
You may wish to use @samp{-fno-builtin} as well as @samp{-traditional}
might compile a file @code{firstClass.C} like this:
@example
-g++ -g -felide-constructors -O -c firstClass.C
+g++ -g -frepo -O -c firstClass.C
@end example
@noindent
-In this example, only @samp{-felide-constructors} is an option meant
+In this example, only @samp{-frepo} is an option meant
only for C++ programs; you can use the other options with any
language supported by GNU CC.
Turn off all access checking. This switch is mainly useful for working
around bugs in the access control code.
-@item -fall-virtual
-Treat all possible member functions as virtual, implicitly.
-All member functions (except for constructor functions and @code{new} or
-@code{delete} member operators) are treated as virtual functions of the
-class where they appear.
-
-This does not mean that all calls to these member functions will be made
-through the internal table of virtual functions. Under some
-circumstances, the compiler can determine that a call to a given virtual
-function can be made directly; in these cases the calls are direct in
-any case.
-
@item -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
this check is normally unnecessary.
+An alternative to using this option is to specify that your
+@code{operator new} does not throw any exceptions; if you declare it
+@samp{throw()}, g++ will check the return value. See also @samp{new
+(nothrow)}.
+
@item -fconserve-space
Put uninitialized or runtime-initialized global variables into the
common segment, as C does. This saves space in the executable at the
completed, you may have an object that is being destroyed twice because
two definitions were merged.
+This option is no longer useful on most targets, now that support has
+been added for putting variables into BSS without making them common.
+
@item -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
Traditional C allowed the character @samp{$} to form part of
identifiers. However, ANSI C and C++ forbid @samp{$} in identifiers.
-@item -fenum-int-equiv
-Anachronistically permit implicit conversion of @code{int} to
-enumeration types. Current C++ allows conversion of @code{enum} to
-@code{int}, but not the other way around.
+@item -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 -fexternal-templates
Cause template instantiations to obey @samp{#pragma interface} and
September 1996, when guiding declarations were removed.
This option implies @samp{-fname-mangling-version-0}, and will not work
-with other name mangling versions.
-
-@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.
+with other name mangling versions. Like all options that change the
+ABI, all C++ code, @emph{including libgcc.a} must be built with the same
+setting of this option.
@item -fhandle-signatures
Recognize the @code{signature} and @code{sigof} keywords for specifying
recognize them. @xref{C++ Signatures, Type Abstraction using
Signatures}.
+@item -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{using-declarations}, @code{using-directives}, and
+@code{namespace-names}, if they involve @code{std}.
+
@item -fhuge-objects
Support virtual function calls for objects that exceed the size
representable by a @samp{short int}. Users should not use this flag by
-default; if you need to use it, the compiler will tell you so. If you
-compile any of your code with this flag, you must compile @emph{all} of
-your code with this flag (including the C++ library, if you use it).
+default; if you need to use it, the compiler will tell you so.
This flag is not useful when compiling with -fvtable-thunks.
-@item -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 -fmemoize-lookups
-@itemx -fsave-memoized
-Use heuristics to compile faster. These heuristics are not enabled by
-default, since they are only effective for certain input files. Other
-input files compile more slowly.
-
-The first time the compiler must build a call to a member function (or
-reference to a data member), it must (1) determine whether the class
-implements member functions of that name; (2) resolve which member
-function to call (which involves figuring out what sorts of type
-conversions need to be made); and (3) check the visibility of the member
-function to the caller. All of this adds up to slower compilation.
-Normally, the second time a call is made to that member function (or
-reference to that data member), it must go through the same lengthy
-process again. This means that code like this:
+Like all options that change the ABI, all C++ code, @emph{including
+libgcc} must be built with the same setting of this option.
-@smallexample
-cout << "This " << p << " has " << n << " legs.\n";
-@end smallexample
+@item -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.
-@noindent
-makes six passes through all three steps. By using a software cache, a
-``hit'' significantly reduces this cost. Unfortunately, using the cache
-introduces another layer of mechanisms which must be implemented, and so
-incurs its own overhead. @samp{-fmemoize-lookups} enables the software
-cache.
-
-Because access privileges (visibility) to members and member functions
-may differ from one function context to the next, G++ may need to flush
-the cache. With the @samp{-fmemoize-lookups} flag, the cache is flushed
-after every function that is compiled. The @samp{-fsave-memoized} flag
-enables the same software cache, but when the compiler determines that
-the context of the last function compiled would yield the same access
-privileges of the next function to compile, it preserves the cache.
-This is most helpful when defining many member functions for the same
-class: with the exception of member functions which are friends of other
-classes, each member function has exactly the same access privileges as
-every other, and the cache need not be flushed.
-
-The code that implements these flags has rotted; you should probably
-avoid using them.
+@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 -fstrict-prototype
-Within an @samp{extern "C"} linkage specification, treat a function
-declaration with no arguments, such as @samp{int foo ();}, as declaring
-the function to take no arguments. Normally, such a declaration means
-that the function @code{foo} can take any combination of arguments, as
-in C. @samp{-pedantic} implies @samp{-fstrict-prototype} unless
-overridden with @samp{-fno-strict-prototype}.
+@item -finit-priority
+Support @samp{__attribute__ ((init_priority (n)))} for controlling the
+order of initialization of file-scope objects. On ELF targets, this
+requires GNU ld 2.10 or later.
-This flag no longer affects declarations with C++ linkage.
+@item -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 -fname-mangling-version-@var{n}
Control the way in which names are mangled. Version 0 is compatible
template <class T, class U> void foo(T t);
@end example
-@item -fno-nonnull-objects
-Don't assume that a reference is initialized to refer to a valid object.
-Although the current C++ Working Paper prohibits null references, some
-old code may rely on them, and you can use @samp{-fno-nonnull-objects}
-to turn on checking.
-
-At the moment, the compiler only does this checking for conversions to
-virtual base classes.
+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},
synonyms for the symbols they refer to. @samp{-ansi} implies
@samp{-foperator-names}.
+@item -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
+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
+the function to take no arguments. Normally, such a declaration means
+that the function @code{foo} can take any combination of arguments, as
+in C. @samp{-pedantic} implies @samp{-fstrict-prototype} unless
+overridden with @samp{-fno-strict-prototype}.
+
+Specifying this option will also suppress implicit declarations of
+functions.
+
+This flag no longer affects declarations with C++ linkage.
+
@item -fsquangle
@itemx -fno-squangle
@samp{-fsquangle} will enable a compressed form of name mangling for
be compiled with this option as well. The compiler has this disabled (the
equivalent of @samp{-fno-squangle}) by default.
+Like all options that change the ABI, all C++ code, @emph{including
+libgcc.a} must be built with the same setting of this option.
+
+@item -ftemplate-depth-@var{n}
+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 -fthis-is-variable
Permit assignment to @code{this}. The incorporation of user-defined
free store management into C++ has made assignment to @samp{this} an
will be emitted in the translation unit containing the first one of
those.
-@item -ftemplate-depth-@var{n}
-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.
+Like all options that change the ABI, all C++ code, @emph{including
+libgcc.a} must be built with the same setting of this option.
@item -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.)
-
-@item -traditional
-For C++ programs (in addition to the effects that apply to both C and
-C++), this has the same effect as @samp{-fthis-is-variable}.
-@xref{C Dialect Options,, Options Controlling C Dialect}.
@end table
In addition, these optimization, warning, and code generation options
@table @code
@item -fno-default-inline
Do not assume @samp{inline} for functions defined inside a class scope.
-@xref{Optimize Options,,Options That Control Optimization}.
+@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 -Wold-style-cast
-@itemx -Woverloaded-virtual
-@itemx -Wtemplate-debugging
-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 -Weffc++
-Warn about violation of some style rules from Effective C++ by Scott Myers.
+@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 +e@var{n}
-Control how virtual function definitions are used, in a fashion
-compatible with @code{cfront} 1.x. @xref{Code Gen Options,,Options for
-Code Generation Conventions}.
+@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.
+@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
A feature to report any failure to conform to ANSI C might be useful in
some instances, but would require considerable additional work and would
-be quite different from @samp{-pedantic}. We recommend, rather, that
-users take advantage of the extensions of GNU C and disregard the
-limitations of other compilers. Aside from certain supercomputers and
-obsolete small machines, there is less and less reason ever to use any
-other C compiler other than for bootstrapping GNU CC.
+be quite different from @samp{-pedantic}. We don't have plans to
+support such a feature in the near future.
@item -pedantic-errors
Like @samp{-pedantic}, except that errors are produced rather than
@item -Wimplicit-int
Warn when a declaration does not specify a type.
-@item -Wimplicit-function-declarations
-Warn whenever a function is used before being declared.
+@item -Wimplicit-function-declaration
+@itemx -Werror-implicit-function-declaration
+Give a warning (or error) whenever a function is used before being
+declared.
@item -Wimplicit
Same as @samp{-Wimplicit-int} and @samp{-Wimplicit-function-}@*
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 -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
Warn if parentheses are omitted in certain contexts, such
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
struct t @{ struct s h; int i; @};
struct t x = @{ 1, 2, 3 @};
@end smallexample
+
+@item
+An aggregate has an initializer which does not initialize all members.
+For example, the following code would cause such a warning, because
+@code{x.h} would be implicitly initialized to zero:
+
+@smallexample
+struct s @{ int f, g, h; @};
+struct s x = @{ 3, 4 @};
+@end smallexample
@end itemize
@item -Wtraditional
@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
Use this option to detect global functions that are not declared in
header files.
+@item -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
+adding the @code{noreturn} attribute, otherwise subtle code generation
+bugs could be introduced.
+
@item -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.
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
+@samp{-Wlong-long} and @samp{-Wno-long-long} are taken into account
+only when @samp{-pedantic} flag is used.
@item -Werror
Make all warnings into errors.
@item d
Dump after delayed branch scheduling, to @file{@var{file}.dbr}.
@item D
+Dump all macro definitions, at the end of preprocessing, in addition to
+normal output.
+@item r
+Dump after RTL generation, to @file{@var{file}.rtl}.
+@item j
+Dump after first jump optimization, to @file{@var{file}.jump}.
+@item F
Dump after purging ADDRESSOF, to @file{@var{file}.addressof}.
@item f
Dump after flow analysis, to @file{@var{file}.flow}.
@item g
Dump after global register allocation, to @file{@var{file}.greg}.
+@item G
+Dump after GCSE, to @file{@var{file}.gcse}.
@item j
Dump after first jump optimization, to @file{@var{file}.jump}.
@item J
@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
Annotate the assembler output with miscellaneous debugging information.
@end table
+@item -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 invokations with different
+options, in particular with and without -g.
+
@item -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
precision than a @code{double} is supposed to have. Similarly for the
x86 architecture. For most programs, the excess precision does only
good, but a few programs rely on the precise definition of IEEE floating
-point. Use @samp{-ffloat-store} for such programs.
+point. Use @samp{-ffloat-store} for such programs, after modifying
+them to store all pertinent intermediate computations into variables.
@item -fno-default-inline
Do not make member functions inline by default merely because they are
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
@item -frerun-loop-opt
Run the loop optimizer twice.
+@item -fgcse
+Perform a global common subexpression elimination pass.
+This pass also performs global constant and copy propagation.
+
@item -fexpensive-optimizations
Perform a number of minor optimizations that are relatively expensive.
+@item -foptimize-register-moves
+@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
+instructions. GNU CC enables this optimization by default with @samp{-O2}
+or higher.
+
+Note @code{-fregmove} and @code{-foptimize-register-moves} are the same
+optimization.
+
@item -fdelayed-branch
If supported for the target machine, attempt to reorder instructions
to exploit instruction slots available after delayed branch
registers and where memory load instructions take more than one cycle.
@item -ffunction-sections
-Place each function into its own section in the output file if the
-target supports arbitrary sections. The function's name determines
-the section's name in the output file.
+@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
+in the output file.
-Use this option on systems where the linker can perform optimizations
+Use these options on systems where the linker can perform optimizations
to improve locality of reference in the instruction space. HPPA
processors running HP-UX and Sparc processors running Solaris 2 have
linkers with such optimizations. Other systems using the ELF object format
as well as AIX may have these optimizations in the future.
-Only use this option when there are significant benefits from doing
-so. When you specify this option, the assembler and linker will
+Only use these options when there are significant benefits from doing
+so. When you specify these options, the assembler and linker will
create larger object and executable files and will also be slower.
You will not be able to use @code{gprof} on all systems if you
specify this option and you may have problems with debugging if
registers around such calls. Such allocation is done only when it
seems to result in better code than would otherwise be produced.
-This option is enabled by default on certain machines, usually those
-which have no call-preserved registers to use instead.
+This option is always enabled by default on certain machines, usually
+those which have no call-preserved registers to use instead.
+
+For all machines, optimization level 2 and higher enables this flag by
+default.
@item -funroll-loops
Perform the optimization of loop unrolling. This is only done for loops
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}
exactly determine which path is taken more often.
@end ifset
-@item -fregmove
-Some machines only support 2 operands per instruction. On such
-machines, GNU CC might have to do extra copies. The @samp{-fregmove}
-option overrides the default for the machine to do the copy before
-register allocation.
+@item -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
+object of one type is assumed never to reside at the same address as an
+object of a different type, unless the types are almost the same. For
+example, an @code{unsigned int} can alias an @code{int}, but not a
+@code{void*} or a @code{double}. A character type may alias any other
+type.
+
+Pay special attention to code like this:
+@example
+union a_union @{
+ int i;
+ double d;
+@};
+
+int f() @{
+ a_union t;
+ t.d = 3.0;
+ return t.i;
+@}
+@end example
+The practice of reading from a different union member than the one most
+recently written to (called ``type-punning'') is common. Even with
+@samp{-fstrict-aliasing}, type-punning is allowed, provided the memory
+is accessed through the union type. So, the code above will work as
+expected. However, this code might not:
+@example
+int f() @{
+ a_union t;
+ int* ip;
+ t.d = 3.0;
+ ip = &t.i;
+ return *ip;
+@}
+@end example
+
+@ifset INTERNALS
+Every language that wishes to perform language-specific alias analysis
+should define a function that computes, given an @code{tree}
+node, an alias set for the node. Nodes in different alias sets are not
+allowed to alias. For an example, see the C front-end function
+@code{c_get_alias_set}.
+@end ifset
+
@end table
@node Preprocessor Options
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 @code{-nostartfiles}
-is used.
+is used. The compiler may generate calls to memcmp, memset, and memcpy
+for System V (and ANSI C) environments or to bcopy and bzero for
+BSD environments. These entries are usually resolved by entries in
+libc. These entry points should be supplied through some other
+mechanism when this option is specified.
@item -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 linker. The compiler may generate calls to memcmp, memset, and memcpy
+for System V (and ANSI C) environments or to bcopy and bzero for
+BSD environments. These entries are usually resolved by entries in
+libc. These entry points should be supplied through some other
+mechanism when this option is specified.
@cindex @code{-lgcc}, use with @code{-nostdlib}
@cindex @code{-nostdlib} and unresolved references
* AMD29K Options::
* ARM Options::
* Thumb Options::
+* MN10200 Options::
* MN10300 Options::
* M32R/D Options::
* M88K Options::
* H8/300 Options::
* SH Options::
* System V Options::
+* TMS320C3x/C4x Options::
* V850 Options::
+* ARC Options::
+* NS32K Options::
@end menu
@node M680x0 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
+@subsection MN10200 Options
+@cindex MN10200 options
+These @samp{-m} options are defined for Matsushita MN10200 architectures:
+@table @code
+
+@item -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.
+
+This option makes symbolic debugging impossible.
+@end table
@node MN10300 Options
@subsection MN10300 Options
@item -mno-mult-bug
Do not generate code to avoid bugs in the multiply instructions for the
MN10300 processors.
+
+@item -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.
+
+This option makes symbolic debugging impossible.
@end table
+
@node M32R/D Options
@subsection M32R/D Options
@cindex M32R/D options
@itemx -mno-powerpc-gpopt
@itemx -mpowerpc-gfxopt
@itemx -mno-powerpc-gfxopt
+@itemx -mpowerpc64
+@itemx -mno-powerpc64
@kindex -mpower
@kindex -mpower2
@kindex -mpowerpc
@kindex -mpowerpc-gpopt
@kindex -mpowerpc-gfxopt
+@kindex -mpowerpc64
GNU CC 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
use the optional PowerPC architecture instructions in the Graphics
group, including floating-point select.
+The @samp{-mpowerpc64} option allows GNU CC to generate the additional
+64-bit instructions that are found in the full PowerPC64 architecture
+and to treat GPRs as 64-bit, doubleword quantities. GNU CC defaults to
+@samp{-mno-powerpc64}.
+
If you specify both @samp{-mno-power} and @samp{-mno-powerpc}, GNU CC
will use only the instructions in the common subset of both
architectures plus some special AIX common-mode calls, and will not use
GNU CC uses that mnemonic irrespective of which of these options is
specified.
-PowerPC assemblers support both the old and new mnemonics, as will later
-POWER assemblers. Current POWER assemblers only support the old
-mnemonics. Specify @samp{-mnew-mnemonics} if you have an assembler that
-supports them, otherwise specify @samp{-mold-mnemonics}.
-
-The default value of these options depends on how GNU CC was configured.
-Specifying @samp{-mcpu=@var{cpu_type}} sometimes overrides the value of
-these option. Unless you are building a cross-compiler, you should
-normally not specify either @samp{-mnew-mnemonics} or
+GNU CC defaults to the mnemonics appropriate for the architecture in
+use. Specifying @samp{-mcpu=@var{cpu_type}} sometimes overrides the
+value of these option. Unless you are building a cross-compiler, you
+should normally not specify either @samp{-mnew-mnemonics} or
@samp{-mold-mnemonics}, but should instead accept the default.
@item -mcpu=@var{cpu_type}
+@kindex -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{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
@itemx -mno-fp-in-toc
@itemx -mno-sum-in-toc
@itemx -mminimal-toc
+@kindex -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, GNU CC will allocate at least one TOC entry for
uses extremely little TOC space. You may wish to use this option
only on files that contain less frequently executed code. @refill
+@item -maix64
+@itemx -maix32
+@kindex -maix64
+@kindex -maix32
+Enable AIX 64-bit 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
+@samp{-mpowerpc}, while @samp{-maix32} disables the 64-bit ABI and
+implies @samp{-mno-powerpc64}. GNU CC defaults to @samp{-maix32}.
+
@item -mxl-call
@itemx -mno-xl-call
+@kindex -mxl-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
handle an obscure K&R C case of calling a function that takes the
address of its arguments with fewer arguments than declared. AIX XL
-compilers assume that floating point arguments which do not fit in the
-RSA are on the stack when they compile a subroutine without
+compilers access floating point arguments which do not fit in the
+RSA from the stack when a subroutine is compiled without
optimization. Because always storing floating-point arguments on the
stack is inefficient and rarely needed, this option is not enabled by
default and only is necessary when calling subroutines compiled by AIX
XL compilers without optimization.
@item -mthreads
+@kindex -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
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
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 GNU CC when linking.
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
-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.
+@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.
+The exceptions are PPC740 and PPC750 which permit the instructions
+usage in little endian mode.
@item -mupdate
@itemx -mno-update
+@kindex -mupdate
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
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
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
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
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
register 2 contains a pointer to a global area pointing to the addresses
used in the program.
-@item -mno-traceback
-@itemx -mtraceback
-On embedded PowerPC systems do not (do) generate a traceback tag before
-the start of the function. This tag can be used by the debugger to
-identify where the start of a function is.
-
@item -mlittle
@itemx -mlittle-endian
On System V.4 and embedded PowerPC systems compile code for the
@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 (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.
+
+@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. 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
@item -membedded-pic
@itemx -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.
-This requires GNU as and GNU ld which do most of the work.
+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
+requires GNU as and GNU ld which do most of the work. This currently
+only works on targets which use ECOFF; it does not work with ELF.
@item -membedded-data
@itemx -mno-embedded-data
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.
value.
@item -nocpp
-Tell the MIPS assembler to not run it's preprocessor over user
+Tell the MIPS assembler to not run its preprocessor over user
assembler files (with a @samp{.s} suffix) when assembling them.
@end table
@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
@item -malign-loops=@var{num}
Align loops to a 2 raised to a @var{num} byte boundary. If
-@samp{-malign-loops} is not specified, the default is 2.
+@samp{-malign-loops} is not specified, the default is 2 unless
+gas 2.8 (or later) is being used in which case the default is
+to align the loop on a 16 byte boundary if it is less than 8
+bytes away.
@item -malign-jumps=@var{num}
Align instructions that are only jumped to to a 2 raised to a @var{num}
byte boundary. If @samp{-malign-jumps} is not specified, the default is
-2 if optimizing for a 386, and 4 if optimizing for a 486.
+2 if optimizing for a 386, and 4 if optimizing for a 486 unless
+gas 2.8 (or later) is being used in which case the default is
+to align the instruction on a 16 byte boundary if it is less
+than 8 bytes away.
@item -malign-functions=@var{num}
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
@item -ml
Compile code for the processor in little endian mode.
+@item -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
Shorten some address references at link time, when possible; uses the
linker option @samp{-relax}.
@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
table.
@end table
+@node ARC Options
+@subsection ARC Options
+@cindex ARC Options
+
+These options are defined for ARC implementations:
+
+@table @code
+@item -EL
+Compile code for little endian mode. This is the default.
+
+@item -EB
+Compile code for big endian mode.
+
+@item -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
+compiled for one cpu to be linked with code compiled for another.
+No facility exists for handling variants that are "almost identical".
+This is an all or nothing option.
+
+@item -mcpu=@var{cpu}
+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}
+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}.
+
+@end table
+
+@node NS32K Options
+@subsection NS32K Options
+@cindex NS32K options
+
+These are the @samp{-m} options defined for the 32000 series. The default
+values for these options depends on which style of 32000 was selected when
+the compiler was configured; the defaults for the most common choices are
+given below.
+
+@table @code
+@item -m32032
+@itemx -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
+Generate output for a 32332. This is the default
+when the compiler is configured for 32332-based systems.
+
+@item -m32532
+@itemx -m32532
+Generate output for a 32532. This is the default
+when the compiler is configured for 32532-based systems.
+
+@item -m32081
+Generate output containing 32081 instructions for floating point.
+This is the default for all systems.
+
+@item -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
+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
+register allocation which generally has a negative impact on
+performance. This option should only be enabled when compiling code
+particularly likely to make heavy use of multiply-add instructions.
+
+@item -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
+Generate output containing library calls for floating point.
+@strong{Warning:} the requisite libraries may not be available.
+
+@item -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
+Do use the bit-field instructions. This is the default for all platforms
+except the pc532.
+
+@item -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.
+
+This calling convention is incompatible with the one normally
+used on Unix, so you cannot use it if you need to call libraries
+compiled with the Unix compiler.
+
+Also, you must provide function prototypes for all functions that
+take variable numbers of arguments (including @code{printf});
+otherwise incorrect code will be generated for calls to those
+functions.
+
+In addition, seriously incorrect code will result if you call a
+function with too many arguments. (Normally, extra arguments are
+harmlessly ignored.)
+
+This option takes its name from the 680x0 @code{rtd} instruction.
+
+
+@item -mregparam
+Use a different function-calling convention where the first two arguments
+are passed in registers.
+
+This calling convention is incompatible with the one normally
+used on Unix, so you cannot use it if you need to call libraries
+compiled with the Unix compiler.
+
+@item -mnoregparam
+Do not pass any arguments in registers. This is the default for all
+targets.
+
+@item -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
+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
+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
+Assume code will be loaded in the first 512MB of virtual address space.
+This is the default for all platforms.
+
+
+@end table
+
+
+
@node Code Gen Options
@section Options for Code Generation Conventions
@cindex code generation conventions
@table @code
@item -fexceptions
-Enable exception handling, and generate extra code needed to propagate
-exceptions. If you do not specify this option, GNU CC enables it by
-default for languages like C++ that normally require exception handling,
+Enable exception handling. Generates extra code needed to propagate
+exceptions. For some targets, this implies generation of frame unwind
+information for all functions. This can produce significant data size
+overhead, although it does not affect execution.
+If you do not specify this option, it is enabled by
+default for languages like C++ which normally require exception handling,
and disabled for languages like C that do not normally require it.
However, when compiling C code that needs to interoperate properly with
exception handlers written in C++, you may need to enable this option.
@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
variables that do not live across a call. Functions compiled this way
will not save and restore the register @var{reg}.
-Use of this flag for a register that has a fixed pervasive role in the
-machine's execution model, such as the stack pointer or frame pointer,
-will produce disastrous results.
+It is an error to used this flag with the frame pointer or stack pointer.
+Use of this flag for other registers that have fixed pervasive roles in
+the machine's execution model will produce disastrous results.
This flag does not have a negative form, because it specifies a
three-way choice.
live across a call. Functions compiled this way will save and restore
the register @var{reg} if they use it.
-Use of this flag for a register that has a fixed pervasive role in the
-machine's execution model, such as the stack pointer or frame pointer,
-will produce disastrous results.
+It is an error to used this flag with the frame pointer or stack pointer.
+Use of this flag for other registers that have fixed pervasive roles in
+the machine's execution model will produce disastrous results.
A different sort of disaster will result from the use of this flag for
a register in which function values may be returned.
@item -fcheck-memory-usage
Generate extra code to check each memory access. GNU CC will generate
code that is suitable for a detector of bad memory accesses such as
-@file{Checker}. If you specify this option, you can not use the
-@code{asm} or @code{__asm__} keywords.
+@file{Checker}.
+
+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.
-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.
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
+@code{__asm__} keywords in functions with memory checking enabled. The
+compiler cannot understand what the @code{asm} statement will do, and
+therefore cannot generate the appropriate code, so it is rejected.
+However, the function attribute @code{no_check_memory_usage} will
+disable memory checking within a function, and @code{asm} statements can
+be put inside such functions. Inline expansion of a non-checked
+function within a checked function is permitted; the inline function's
+memory accesses won't be checked, but the rest will.
+
+If you move your @code{asm} statements to non-checked inline functions,
+but they do access memory, you can add calls to the support code in your
+inline function, to indicate any reads, writes, or copies being done.
+These calls would be similar to those done in the stubs described above.
+
+@c FIXME: The support-routine interface is defined by the compiler and
+@c should be documented!
+
@item -fprefix-function-name
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 example
This option is designed to be used with @samp{-fcheck-memory-usage}.
+@item -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
+function and its call site. (On some platforms,
+@code{__builtin_return_address} does not work beyond the current
+function, so the call site information may not be available to the
+profiling functions otherwise.)
+
+@example
+void __cyg_profile_func_enter (void *this_fn, void *call_site);
+void __cyg_profile_func_exit (void *this_fn, void *call_site);
+@end example
+
+The first argument is the address of the start of the current function,
+which may be looked up exactly in the symbol table.
+
+This instrumentation is also done for functions expanded inline in other
+functions. The profiling calls will indicate where, conceptually, the
+inline function is entered and exited. This means that addressable
+versions of such functions must be available. If all your uses of a
+function are expanded inline, this may mean an additional expansion of
+code size. If you use @samp{extern inline} in your C code, an
+addressable version of such functions must be provided. (This is
+normally the case anyways, but if you get lucky and the optimizer always
+expands the functions inline, you might have gotten away without
+providing static copies.)
+
+A function may be given the attribute @code{no_instrument_function}, in
+which case this instrumentation will not be done. This can be used, for
+example, for the profiling functions listed above, high-priority
+interrupt routines, and any functions from which the profiling functions
+cannot safely be called (perhaps signal handlers, if the profiling
+routines generate output or allocate memory).
+
@item -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
a single-threaded environment since stack overflow is automatically
detected on nearly all systems if there is only one stack.
-@item -fexceptions
-Enable exception handling. For some targets, this implies
-generation of frame unwind information for all functions, which can produce
-significant data size overhead, though it does not affect execution.
-
-This option is on by default for languages that support exception
-handling (such as C++), and off for those that don't (such as C).
-
-@item +e0
-@itemx +e1
-Control whether virtual function definitions in classes are used to
-generate code, or only to define interfaces for their callers. (C++
-only).
-
-These options are provided for compatibility with @code{cfront} 1.x
-usage; the recommended alternative GNU C++ usage is in flux. @xref{C++
-Interface,,Declarations and Definitions in One Header}.
-
-With @samp{+e0}, virtual function definitions in classes are declared
-@code{extern}; the declaration is used only as an interface
-specification, not to generate code for the virtual functions (in this
-compilation).
-
-With @samp{+e1}, G++ actually generates the code implementing virtual
-functions defined in the code, and makes them publicly visible.
-
@cindex aliasing of parameters
@cindex parameters, aliased
@item -fargument-alias
Each language will automatically use whatever option is required by
the language standard. You should not need to use these options yourself.
+
+@item -fleading-underscore
+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.
+
+Be warned that you should know what you are doing when invoking this
+option, and that not all targets provide complete support for it.
@end table
@node Environment Variables
@cindex environment variables
This section describes several environment variables that affect how GNU
-CC operates. They work by specifying directories or prefixes to use
-when searching for various kinds of files.
+CC operates. Some of them work by specifying directories or prefixes to use
+when searching for various kinds of files. Some are used to specify other
+aspects of the compilation environment.
@ifclear INTERNALS
Note that you can also specify places to search using options such as
@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
name from the source file name. Or the value can have the form
@samp{@var{file} @var{target}}, in which case the rules are written to
file @var{file} using @var{target} as the target name.
+
+@item LANG
+@findex LANG
+@cindex locale definition
+This variable is used to pass locale information to the compiler. One way in
+which this information is used is to determine the character set to be used
+when character literals, string literals and comments are parsed in C and C++.
+When the compiler is configured to allow multibyte characters,
+the following values for @code{LANG} are recognized:
+
+@table @code
+@item C-JIS
+Recognize JIS characters.
+@item C-SJIS
+Recognize SJIS characters.
+@item C-EUCJP
+Recognize EUCJP characters.
+@end table
+
+If @code{LANG} is not defined, or if it has some other value, then the
+compiler will use mblen and mbtowc as defined by the default locale to
+recognize and translate multibyte characters.
@end table
@node Running Protoize
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