-@c Copyright (C) 1988, 89, 92-98, 1999 Free Software Foundation, Inc.
+@c Copyright (C) 1988, 89, 92-99, 2000 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 --help -x @var{language}
+-c -S -E -o @var{file} -pipe -pass-exit-codes -v --help -x @var{language}
@end smallexample
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@smallexample
--ansi -flang-isoc9x -fallow-single-precision -fcond-mismatch -fno-asm
+-ansi -fstd -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
-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} -fvtable-thunks
+-fsquangle -ftemplate-depth-@var{n} -fuse-cxa-atexit -fvtable-thunks
-nostdinc++ -Wctor-dtor-privacy -Wno-deprecated -Weffc++
-Wno-non-template-friend
-Wnon-virtual-dtor -Wold-style-cast -Woverloaded-virtual
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@smallexample
-fsyntax-only -pedantic -pedantic-errors
--w -W -Wall -Waggregate-return -Wbad-function-cast
+-w -W -Wall -Waggregate-return
-Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment
-Wconversion -Werror -Wformat
-Wid-clash-@var{len} -Wimplicit -Wimplicit-int
-Werror-implicit-function-declaration -Wfloat-equal -Winline
-Wlarger-than-@var{len} -Wlong-long
-Wmain -Wmissing-declarations -Wmissing-noreturn
--Wmissing-prototypes -Wmultichar -Wnested-externs -Wno-import
+-Wmultichar -Wno-import -Wpacked -Wpadded
-Wparentheses -Wpointer-arith -Wredundant-decls
--Wreturn-type -Wshadow -Wsign-compare -Wstrict-prototypes
--Wswitch -Wtraditional
+-Wreturn-type -Wshadow -Wsign-compare -Wswitch
-Wtrigraphs -Wundef -Wuninitialized -Wunknown-pragmas -Wunreachable-code
-Wunused -Wwrite-strings
@end smallexample
+@item C-only Warning Options
+@smallexample
+-Wbad-function-cast -Wmissing-prototypes -Wnested-externs
+-Wstrict-prototypes -Wtraditional
+@end smallexample
+
@item Debugging Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
@smallexample
-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040
-m68060 -mcpu32 -m5200 -m68881 -mbitfield -mc68000 -mc68020
-mfpa -mnobitfield -mrtd -mshort -msoft-float -mpcrel
--malign-int
+-malign-int -mstrict-align
@emph{VAX Options}
-mg -mgnu -munix
-mtune=@var{cpu type}
-mcmodel=@var{code model}
-m32 -m64
--mapp-regs -mbroken-saverestore -mcypress -mepilogue
--mflat -mfpu -mhard-float -mhard-quad-float
--mimpure-text -mlive-g0 -mno-app-regs -mno-epilogue
--mno-flat -mno-fpu -mno-impure-text
--mno-stack-bias -mno-unaligned-doubles
+-mapp-regs -mbroken-saverestore -mcypress
+-mepilogue -mfaster-structs -mflat
+-mfpu -mhard-float -mhard-quad-float
+-mimpure-text -mlive-g0 -mno-app-regs
+-mno-epilogue -mno-faster-structs -mno-flat -mno-fpu
+-mno-impure-text -mno-stack-bias -mno-unaligned-doubles
-msoft-float -msoft-quad-float -msparclite -mstack-bias
-msupersparc -munaligned-doubles -mv8
-mapcs-reentrant -mno-apcs-reentrant
-msched-prolog -mno-sched-prolog
-mlittle-endian -mbig-endian -mwords-little-endian
--mshort-load-bytes -mno-short-load-bytes -mshort-load-words -mno-short-load-words
+-malignment-traps -mno-alignment-traps
-msoft-float -mhard-float -mfpe
-mthumb-interwork -mno-thumb-interwork
-mcpu= -march= -mfpe=
@emph{MN10300 Options}
-mmult-bug
-mno-mult-bug
+-mam33
+-mno-am33
-mrelax
@emph{M32R/D Options}
-mminimum-fp-blocks -mnohc-struct-return
@emph{MIPS Options}
--mabicalls -mcpu=@var{cpu type} -membedded-data
+-mabicalls -mcpu=@var{cpu type} -membedded-data -muninit-const-in-rodata
-membedded-pic -mfp32 -mfp64 -mgas -mgp32 -mgp64
-mgpopt -mhalf-pic -mhard-float -mint64 -mips1
-mips2 -mips3 -mips4 -mlong64 -mlong32 -mlong-calls -mmemcpy
-mmips-as -mmips-tfile -mno-abicalls
--mno-embedded-data -mno-embedded-pic
+-mno-embedded-data -mno-uninit-const-in-rodata -mno-embedded-pic
-mno-gpopt -mno-long-calls
-mno-memcpy -mno-mips-tfile -mno-rnames -mno-stats
-mrnames -msoft-float
-m4650 -msingle-float -mmad
-mstats -EL -EB -G @var{num} -nocpp
-mabi=32 -mabi=n32 -mabi=64 -mabi=eabi
+-mno-crt0
@emph{i386 Options}
-mcpu=@var{cpu type}
-mreg-alloc=@var{list} -mregparm=@var{num}
-malign-jumps=@var{num} -malign-loops=@var{num}
-malign-functions=@var{num} -mpreferred-stack-boundary=@var{num}
+-mthreads
@emph{HPPA Options}
-march=@var{architecture type}
@xref{Code Gen Options,,Options for Code Generation Conventions}.
@smallexample
-fcall-saved-@var{reg} -fcall-used-@var{reg}
--fexceptions -ffixed-@var{reg} -finhibit-size-directive
+-fexceptions -funwind-tables -ffixed-@var{reg} -finhibit-size-directive
-fcheck-memory-usage -fprefix-function-name
-fno-common -fno-ident -fno-gnu-linker
-fpcc-struct-return -fpic -fPIC
-freg-struct-return -fshared-data -fshort-enums
-fshort-double -fvolatile -fvolatile-global -fvolatile-static
-fverbose-asm -fpack-struct -fstack-check
+-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym}
-fargument-alias -fargument-noalias
-fargument-noalias-global
-fleading-underscore
Turn off any specification of a language, so that subsequent files are
handled according to their file name suffixes (as they are if @samp{-x}
has not been used at all).
+
+@item -pass-exit-codes
+Normally the @code{gcc} program will exit with the code of 1 if any
+phase of the compiler returns a non-success return code. If you specify
+@samp{-pass-exit-codes}, the @code{gcc} program will instead return with
+numerically highest error produced by any phase that returned an error
+indication.
@end table
If you only want some of the stages of compilation, you can use
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.
+@item -fstd=
+Determine the language standard. A value for this option must be provided;
+possible values are
+
+@itemize @minus
+@item iso9899:1990
+Same as -ansi
+
+@item iso9899:199409
+ISO C as modified in amend. 1
+
+@item iso9899:199x
+ISO C 9x
+
+@item c89
+same as -std=iso9899:1990
+
+@item c9x
+same as -std=iso9899:199x
+
+@item gnu89
+default, iso9899:1990 + gnu extensions
+
+@item gnu9x
+iso9899:199x + gnu extensions
+@end itemize
-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.
+Even when this option is not specified, you can still use some of the
+features of newer standards in so far as they do not conflict with
+previous C standards. For example, you may use @code{__restrict__} even
+when -fstd=c9x is not specified.
@item -fno-asm
Do not recognize @code{asm}, @code{inline} or @code{typeof} as a
@findex abs
@findex alloca
@findex cos
+@findex cosf
+@findex cosl
@findex exit
+@findex _exit
@findex fabs
+@findex fabsf
+@findex fabsl
@findex ffs
@findex labs
@findex memcmp
@findex memcpy
+@findex memset
@findex sin
+@findex sinf
+@findex sinl
@findex sqrt
+@findex sqrtf
+@findex sqrtl
@findex strcmp
@findex strcpy
@findex strlen
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}.
+@code{abs}, @code{alloca}, @code{cos}, @code{cosf}, @code{cosl},
+@code{exit}, @code{_exit}, @code{fabs}, @code{fabsf}, @code{fabsl},
+@code{ffs}, @code{labs}, @code{memcmp}, @code{memcpy}, @code{memset},
+@code{sin}, @code{sinf}, @code{sinl}, @code{sqrt}, @code{sqrtf},
+@code{sqrtl}, @code{strcmp}, @code{strcpy}, and @code{strlen}.
GCC normally generates special code to handle certain builtin functions
more efficiently; for instance, calls to @code{alloca} may become single
cannot set a breakpoint on those calls, nor can you change the behavior
of the functions by linking with a different library.
-The @samp{-ansi} option prevents @code{alloca} and @code{ffs} from being
-builtin functions, since these functions do not have an ANSI standard
-meaning.
+The @samp{-ansi} option prevents @code{alloca}, @code{ffs} and @code{_exit}
+from being builtin functions, since these functions do not have an ANSI
+standard meaning.
@item -fhosted
@cindex hosted environment
endless recursions during template class instantiation. ANSI/ISO C++
conforming programs must not rely on a maximum depth greater than 17.
+@item -fuse-cxa-atexit
+Register destructors for objects with static storage duration with the
+@code{__cxa_atexit} function rather than the @code{atexit} function.
+This option is required for fully standards-compliant handling of static
+destructors, but will only work if your C library supports
+@code{__cxa_atexit}.
+
@item -fvtable-thunks
Use @samp{thunks} to implement the virtual function dispatch table
(@samp{vtable}). The traditional (cfront-style) approach to
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
as when there is an assignment in a context where a truth value
@item -Wfloat-equal
Warn if floating point values are used in equality comparisons.
-@item -Wtraditional
+@item -Wtraditional (C only)
Warn about certain constructs that behave differently in traditional and
ANSI C.
@item
A non-@code{static} function declaration follows a @code{static} one.
This construct is not accepted by some traditional C compilers.
+
+@item
+The ANSI type of an integer constant has a different width or
+signedness from its traditional type. This warning is only issued if
+the base of the constant is ten. I.e. hexadecimal or octal values, which
+typically represent bit patterns, are not warned about.
+
+@item
+Usage of ANSI string concatenation is detected.
@end itemize
@item -Wundef
convenience in calculations with @code{void *} pointers and pointers
to functions.
-@item -Wbad-function-cast
+@item -Wbad-function-cast (C only)
Warn whenever a function call is cast to a non-matching type.
For example, warn if @code{int malloc()} is cast to @code{anything *}.
called. (In languages where you can return an array, this also elicits
a warning.)
-@item -Wstrict-prototypes
+@item -Wstrict-prototypes (C only)
Warn if a function is declared or defined without specifying the
argument types. (An old-style function definition is permitted without
a warning if preceded by a declaration which specifies the argument
types.)
-@item -Wmissing-prototypes
+@item -Wmissing-prototypes (C only)
Warn if a global function is defined without a previous prototype
declaration. This warning is issued even if the definition itself
provides a prototype. The aim is to detect global functions that fail
adding the @code{noreturn} attribute, otherwise subtle code generation
bugs could be introduced.
+@item -Wpacked
+Warn if a structure is given the packed attribute, but the packed
+attribute has no effect on the layout or size of the structure.
+Such structures may be mis-aligned for little benefit. For
+instance, in this code, the variable @code{f.x} in @code{struct bar}
+will be misaligned even though @code{struct bar} does not itself
+have the packed attribute:
+
+@smallexample
+@group
+struct foo @{
+ int x;
+ char a, b, c, d;
+@} __attribute__((packed));
+struct bar @{
+ char z;
+ struct foo f;
+@};
+@end group
+@end smallexample
+
+@item -Wpadded
+Warn if padding is included in a structure, either to align an element
+of the structure or to align the whole structure. Sometimes when this
+happens it is possible to rearrange the fields of the structure to
+reduce the padding and so make the structure smaller.
+
@item -Wredundant-decls
Warn if anything is declared more than once in the same scope, even in
cases where multiple declaration is valid and changes nothing.
-@item -Wnested-externs
+@item -Wnested-externs (C only)
Warn if an @code{extern} declaration is encountered within a function.
@item -Wunreachable-code
not presently supported with -mpcrel, though this could be supported for
68020 and higher processors.
+@item -mno-strict-align
+@itemx -mstrict-align
+@kindex -mstrict-align
+Do not (do) assume that unaligned memory references will be handled by
+the system.
+
@end table
@node VAX Options
generated by other compilers. It is not the default because it results
in a performance loss, especially for floating point code.
+@item -mno-faster-structs
+@itemx -mfaster-structs
+With @samp{-mfaster-structs}, the compiler assumes that structures
+should have 8 byte alignment. This enables the use of pairs of
+@code{ldd} and @code{std} instructions for copies in structure
+assignment, in place of twice as many @code{ld} and @code{st} pairs.
+However, the use of this changed alignment directly violates the Sparc
+ABI. Thus, it's intended only for use on targets where the developer
+acknowledges that their resulting code will not be directly in line with
+the rules of the ABI.
+
@item -mv8
@itemx -msparclite
These two options select variations on the SPARC architecture.
big-endian ARM processors generated by versions of the compiler prior to
2.8.
+@item -malignment-traps
+@kindex -malignment-traps
+Generate code that will not trap if the MMU has alignment traps enabled.
+On ARM architectures prior to ARMv4, there were no instructions to
+access half-word objects stored in memory. However, when reading from
+memory a feature of the ARM architecture allows a word load to be used,
+even if the address is unaligned, and the processor core will rotate the
+data as it is being loaded. This option tells the compiler that such
+misaligned accesses will cause a MMU trap and that it should instead
+synthesise the access as a series of byte accesses. The compiler can
+still use word accesses to load half-word data if it knows that the
+address is aligned to a word boundary.
+
+This option is ignored when compiling for ARM architecture 4 or later,
+since these processors have instructions to directly access half-word
+objects in memory.
+
+@item -mno-alignment-traps
+@kindex -mno-alignment-traps
+Generate code that assumes that the MMU will not trap unaligned
+accesses. This produces better code when the target instruction set
+does not have half-word memory operations (implementations prior to
+ARMv4).
+
+Note that you cannot use this option to access unaligned word objects,
+since the processor will only fetch one 32-bit aligned object from
+memory.
+
+The default setting for most targets is -mno-alignment-traps, since
+this produces better code when there are no half-word memory
+instructions available.
+
@item -mshort-load-bytes
@kindex -mshort-load-bytes
-Do not try to load half-words (eg @samp{short}s) by loading a word from
-an unaligned address. For some targets the MMU is configured to trap
-unaligned loads; use this option to generate code that is safe in these
-environments.
+This is a depreciated alias for @samp{-malignment-traps}.
@item -mno-short-load-bytes
@kindex -mno-short-load-bytes
-Use unaligned word loads to load half-words (eg @samp{short}s). This
-option produces more efficient code, but the MMU is sometimes configured
-to trap these instructions.
+This is a depreciated alias for @samp{-mno-alignment-traps}.
@item -mshort-load-words
@kindex -mshort-load-words
-This is a synonym for @samp{-mno-short-load-bytes}.
+This is a depreciated alias for @samp{-mno-alignment-traps}.
@item -mno-short-load-words
@kindex -mno-short-load-words
-This is a synonym for @samp{-mshort-load-bytes}.
+This is a depreciated alias for @samp{-malignment-traps}.
@item -mbsd
@kindex -mbsd
Do not generate code to avoid bugs in the multiply instructions for the
MN10300 processors.
+@item -mam33
+Generate code which uses features specific to the AM33 processor.
+
+@item -mno-am33
+Do not generate code which uses features specific to the AM33 processor. This
+is the default.
+
@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
slightly slower code than the default, but reduces the amount of RAM required
when executing, and thus may be preferred for some embedded systems.
+@item -muninit-const-in-rodata
+@itemx -mno-uninit-const-in-rodata
+When used together with -membedded-data, it will always store uninitialized
+const variables in the read-only data section.
+
@item -msingle-float
@itemx -mdouble-float
The @samp{-msingle-float} switch tells gcc to assume that the floating
@item -nocpp
Tell the MIPS assembler to not run its preprocessor over user
assembler files (with a @samp{.s} suffix) when assembling them.
+
+@item -no-crt0
+Do not include the default crt0.
@end table
@ifset INTERNALS
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}.
+
+@item -mthreads
+@kindex -mthreads
+Support thread-safe exception handling on @samp{Mingw32}. Code that relies
+on thread-safe exception handling must compile and link all code with the
+@samp{-mthreads} option. When compiling, @samp{-mthreads} defines
+@samp{-D_MT}; when linking, it links in a special thread helper library
+@samp{-lmingwthrd} which cleans up per thread exception handling data.
@end table
@node HPPA Options
disable this option if you are compiling older C++ programs that don't
use exception handling.
+@item -funwind-tables
+Similar to @code{-fexceptions}, except that it will just generate any needed
+static data, but will not affect the generated code in any other way.
+You will normally not enable this option; instead, a language processor
+that needs this handling would enable it on your behalf.
+
@item -fpcc-struct-return
Return ``short'' @code{struct} and @code{union} values in memory like
longer ones, rather than in registers. This convention is less
a single-threaded environment since stack overflow is automatically
detected on nearly all systems if there is only one stack.
+Note that this switch does not actually cause checking to be done; the
+operating system must do that. The switch causes generation of code
+to ensure that the operating system sees the stack being extended.
+
+@item -fstack-limit-register=@var{reg}
+@itemx -fstack-limit-symbol=@var{sym}
+@itemx -fno-stack-limit
+Generate code to ensure that the stack does not grow beyond a certain value,
+either the value of a register or the address of a symbol. If the stack
+would grow beyond the value, a signal is raised. For most targets,
+the signal is raised before the stack overruns the boundary, so
+it is possible to catch the signal without taking special precautions.
+
+For instance, if the stack starts at address @samp{0x80000000} and grows
+downwards you can use the flags
+@samp{-fstack-limit-symbol=__stack_limit}
+@samp{-Wl,--defsym,__stack_limit=0x7ffe0000} which will enforce a stack
+limit of 128K.
+
@cindex aliasing of parameters
@cindex parameters, aliased
@item -fargument-alias
when this prefix is combined with the name of a subprogram, but you can
specify a prefix that ends with a slash if you wish.
+If @code{GCC_EXEC_PREFIX} is not set, GNU CC will attempt to figure out
+an appropriate prefix to use based on the pathname it was invoked with.
+
If GCC cannot find the subprogram using the specified prefix, it
tries looking in the usual places for the subprogram.
the @var{compilation-options}, they are ignored.
@item -C
-Rename files to end in @samp{.C} instead of @samp{.c}.
-This is convenient if you are converting a C program to C++.
-This option applies only to @code{protoize}.
+Rename files to end in @samp{.C}, or @samp{.cc} for DOS-based file
+systems, instead of @samp{.c}. This is convenient if you are converting
+a C program to C++. This option applies only to @code{protoize}.
@item -g
Add explicit global declarations. This means inserting explicit
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