-@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-@c 1999, 2000, 2001 Free Software Foundation, Inc.
+@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
+@c 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
+@c Free Software Foundation, Inc.
@c This is part of the GCC manual.
-@c For copying conditions, see the file gcc.texi.
-
-@node Config
-@chapter The Configuration File
+@c For copying conditions, see the file gccint.texi.
+
+@node Host Config
+@chapter Host Configuration
+@cindex host configuration
+
+Most details about the machine and system on which the compiler is
+actually running are detected by the @command{configure} script. Some
+things are impossible for @command{configure} to detect; these are
+described in two ways, either by macros defined in a file named
+@file{xm-@var{machine}.h} or by hook functions in the file specified
+by the @var{out_host_hook_obj} variable in @file{config.gcc}. (The
+intention is that very few hosts will need a header file but nearly
+every fully supported host will need to override some hooks.)
+
+If you need to define only a few macros, and they have simple
+definitions, consider using the @code{xm_defines} variable in your
+@file{config.gcc} entry instead of creating a host configuration
+header. @xref{System Config}.
+
+@menu
+* Host Common:: Things every host probably needs implemented.
+* Filesystem:: Your host can't have the letter `a' in filenames?
+* Host Misc:: Rare configuration options for hosts.
+@end menu
+
+@node Host Common
+@section Host Common
+@cindex host hooks
+@cindex host functions
+
+Some things are just not portable, even between similar operating systems,
+and are too difficult for autoconf to detect. They get implemented using
+hook functions in the file specified by the @var{host_hook_obj}
+variable in @file{config.gcc}.
+
+@deftypefn {Host Hook} void HOST_HOOKS_EXTRA_SIGNALS (void)
+This host hook is used to set up handling for extra signals. The most
+common thing to do in this hook is to detect stack overflow.
+@end deftypefn
+
+@deftypefn {Host Hook} {void *} HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t @
+ @var{size}, int @var{fd})
+This host hook returns the address of some space that is likely to be
+free in some subsequent invocation of the compiler. We intend to load
+the PCH data at this address such that the data need not be relocated.
+The area should be able to hold @var{size} bytes. If the host uses
+@code{mmap}, @var{fd} is an open file descriptor that can be used for
+probing.
+@end deftypefn
+
+@deftypefn {Host Hook} int HOST_HOOKS_GT_PCH_USE_ADDRESS (void * @var{address}, @
+ size_t @var{size}, int @var{fd}, size_t @var{offset})
+This host hook is called when a PCH file is about to be loaded.
+We want to load @var{size} bytes from @var{fd} at @var{offset}
+into memory at @var{address}. The given address will be the result of
+a previous invocation of @code{HOST_HOOKS_GT_PCH_GET_ADDRESS}.
+Return @minus{}1 if we couldn't allocate @var{size} bytes at @var{address}.
+Return 0 if the memory is allocated but the data is not loaded. Return 1
+if the hook has performed everything.
+
+If the implementation uses reserved address space, free any reserved
+space beyond @var{size}, regardless of the return value. If no PCH will
+be loaded, this hook may be called with @var{size} zero, in which case
+all reserved address space should be freed.
+
+Do not try to handle values of @var{address} that could not have been
+returned by this executable; just return @minus{}1. Such values usually
+indicate an out-of-date PCH file (built by some other GCC executable),
+and such a PCH file won't work.
+@end deftypefn
+
+@deftypefn {Host Hook} size_t HOST_HOOKS_GT_PCH_ALLOC_GRANULARITY (void);
+This host hook returns the alignment required for allocating virtual
+memory. Usually this is the same as getpagesize, but on some hosts the
+alignment for reserving memory differs from the pagesize for committing
+memory.
+@end deftypefn
+
+@node Filesystem
+@section Host Filesystem
@cindex configuration file
@cindex @file{xm-@var{machine}.h}
-The configuration file @file{xm-@var{machine}.h} contains macro
-definitions that describe the machine and system on which the compiler
-is running, unlike the definitions in @file{@var{machine}.h}, which
-describe the machine for which the compiler is producing output. Most
-of the values in @file{xm-@var{machine}.h} are actually the same on all
-machines that GCC runs on, so large parts of all configuration files
-are identical. But there are some macros that vary:
+GCC needs to know a number of things about the semantics of the host
+machine's filesystem. Filesystems with Unix and MS-DOS semantics are
+automatically detected. For other systems, you can define the
+following macros in @file{xm-@var{machine}.h}.
+
+@ftable @code
+@item HAVE_DOS_BASED_FILE_SYSTEM
+This macro is automatically defined by @file{system.h} if the host
+file system obeys the semantics defined by MS-DOS instead of Unix.
+DOS file systems are case insensitive, file specifications may begin
+with a drive letter, and both forward slash and backslash (@samp{/}
+and @samp{\}) are directory separators.
+
+@item DIR_SEPARATOR
+@itemx DIR_SEPARATOR_2
+If defined, these macros expand to character constants specifying
+separators for directory names within a file specification.
+@file{system.h} will automatically give them appropriate values on
+Unix and MS-DOS file systems. If your file system is neither of
+these, define one or both appropriately in @file{xm-@var{machine}.h}.
+
+However, operating systems like VMS, where constructing a pathname is
+more complicated than just stringing together directory names
+separated by a special character, should not define either of these
+macros.
-@table @code
-@findex USG
-@item USG
-Define this macro if the host system is System V@.
+@item PATH_SEPARATOR
+If defined, this macro should expand to a character constant
+specifying the separator for elements of search paths. The default
+value is a colon (@samp{:}). DOS-based systems usually, but not
+always, use semicolon (@samp{;}).
-@findex VMS
@item VMS
Define this macro if the host system is VMS@.
-@findex FATAL_EXIT_CODE
+@item HOST_OBJECT_SUFFIX
+Define this macro to be a C string representing the suffix for object
+files on your host machine. If you do not define this macro, GCC will
+use @samp{.o} as the suffix for object files.
+
+@item HOST_EXECUTABLE_SUFFIX
+Define this macro to be a C string representing the suffix for
+executable files on your host machine. If you do not define this macro,
+GCC will use the null string as the suffix for executable files.
+
+@item HOST_BIT_BUCKET
+A pathname defined by the host operating system, which can be opened as
+a file and written to, but all the information written is discarded.
+This is commonly known as a @dfn{bit bucket} or @dfn{null device}. If
+you do not define this macro, GCC will use @samp{/dev/null} as the bit
+bucket. If the host does not support a bit bucket, define this macro to
+an invalid filename.
+
+@item UPDATE_PATH_HOST_CANONICALIZE (@var{path})
+If defined, a C statement (sans semicolon) that performs host-dependent
+canonicalization when a path used in a compilation driver or
+preprocessor is canonicalized. @var{path} is a malloc-ed path to be
+canonicalized. If the C statement does canonicalize @var{path} into a
+different buffer, the old path should be freed and the new buffer should
+have been allocated with malloc.
+
+@item DUMPFILE_FORMAT
+Define this macro to be a C string representing the format to use for
+constructing the index part of debugging dump file names. The resultant
+string must fit in fifteen bytes. The full filename will be the
+concatenation of: the prefix of the assembler file name, the string
+resulting from applying this format to an index number, and a string
+unique to each dump file kind, e.g.@: @samp{rtl}.
+
+If you do not define this macro, GCC will use @samp{.%02d.}. You should
+define this macro if using the default will create an invalid file name.
+
+@item DELETE_IF_ORDINARY
+Define this macro to be a C statement (sans semicolon) that performs
+host-dependent removal of ordinary temp files in the compilation driver.
+
+If you do not define this macro, GCC will use the default version. You
+should define this macro if the default version does not reliably remove
+the temp file as, for example, on VMS which allows multiple versions
+of a file.
+
+@item HOST_LACKS_INODE_NUMBERS
+Define this macro if the host filesystem does not report meaningful inode
+numbers in struct stat.
+@end ftable
+
+@node Host Misc
+@section Host Misc
+@cindex configuration file
+@cindex @file{xm-@var{machine}.h}
+
+@ftable @code
@item FATAL_EXIT_CODE
A C expression for the status code to be returned when the compiler
exits after serious errors. The default is the system-provided macro
@samp{EXIT_FAILURE}, or @samp{1} if the system doesn't define that
macro. Define this macro only if these defaults are incorrect.
-@findex SUCCESS_EXIT_CODE
@item SUCCESS_EXIT_CODE
A C expression for the status code to be returned when the compiler
exits without serious errors. (Warnings are not serious errors.) The
the system doesn't define that macro. Define this macro only if these
defaults are incorrect.
-@findex HOST_WORDS_BIG_ENDIAN
-@item HOST_WORDS_BIG_ENDIAN
-Defined if the host machine stores words of multi-word values in
-big-endian order. (GCC does not depend on the host byte ordering
-within a word.)
-
-@findex HOST_FLOAT_WORDS_BIG_ENDIAN
-@item HOST_FLOAT_WORDS_BIG_ENDIAN
-Define this macro to be 1 if the host machine stores @code{DFmode},
-@code{XFmode} or @code{TFmode} floating point numbers in memory with the
-word containing the sign bit at the lowest address; otherwise, define it
-to be zero.
-
-This macro need not be defined if the ordering is the same as for
-multi-word integers.
-
-@findex HOST_FLOAT_FORMAT
-@item HOST_FLOAT_FORMAT
-A numeric code distinguishing the floating point format for the host
-machine. See @code{TARGET_FLOAT_FORMAT} in @ref{Storage Layout} for the
-alternatives and default.
-
-@findex HOST_BITS_PER_CHAR
-@item HOST_BITS_PER_CHAR
-A C expression for the number of bits in @code{char} on the host
-machine.
-
-@findex HOST_BITS_PER_SHORT
-@item HOST_BITS_PER_SHORT
-A C expression for the number of bits in @code{short} on the host
-machine.
-
-@findex HOST_BITS_PER_INT
-@item HOST_BITS_PER_INT
-A C expression for the number of bits in @code{int} on the host
-machine.
-
-@findex HOST_BITS_PER_LONG
-@item HOST_BITS_PER_LONG
-A C expression for the number of bits in @code{long} on the host
-machine.
-
-@findex HOST_BITS_PER_LONGLONG
-@item HOST_BITS_PER_LONGLONG
-A C expression for the number of bits in @code{long long} on the host
-machine.
-
-@findex ONLY_INT_FIELDS
-@item ONLY_INT_FIELDS
-Define this macro to indicate that the host compiler only supports
-@code{int} bit-fields, rather than other integral types, including
-@code{enum}, as do most C compilers.
-
-@findex OBSTACK_CHUNK_SIZE
-@item OBSTACK_CHUNK_SIZE
-A C expression for the size of ordinary obstack chunks.
-If you don't define this, a usually-reasonable default is used.
-
-@findex OBSTACK_CHUNK_ALLOC
-@item OBSTACK_CHUNK_ALLOC
-The function used to allocate obstack chunks.
-If you don't define this, @code{xmalloc} is used.
-
-@findex OBSTACK_CHUNK_FREE
-@item OBSTACK_CHUNK_FREE
-The function used to free obstack chunks.
-If you don't define this, @code{free} is used.
-
-@findex USE_C_ALLOCA
@item USE_C_ALLOCA
-Define this macro to indicate that the compiler is running with the
-@code{alloca} implemented in C@. This version of @code{alloca} can be
-found in the file @file{alloca.c}; to use it, you must also alter the
-@file{Makefile} variable @code{ALLOCA}. (This is done automatically
-for the systems on which we know it is needed.)
-
-If you do define this macro, you should probably do it as follows:
-
-@example
-#ifndef __GNUC__
-#define USE_C_ALLOCA
-#else
-#define alloca __builtin_alloca
-#endif
-@end example
-
-@noindent
-so that when the compiler is compiled with GCC it uses the more
-efficient built-in @code{alloca} function.
-
-@item FUNCTION_CONVERSION_BUG
-@findex FUNCTION_CONVERSION_BUG
-Define this macro to indicate that the host compiler does not properly
-handle converting a function value to a pointer-to-function when it is
-used in an expression.
-
-@findex MULTIBYTE_CHARS
-@item MULTIBYTE_CHARS
-Define this macro to enable support for multibyte characters in the
-input to GCC@. This requires that the host system support the ISO C
-library functions for converting multibyte characters to wide
-characters.
-
-@findex POSIX
-@item POSIX
-Define this if your system is POSIX.1 compliant.
-
-@findex PATH_SEPARATOR
-@item PATH_SEPARATOR
-Define this macro to be a C character constant representing the
-character used to separate components in paths. The default value is
-the colon character
-
-@findex DIR_SEPARATOR
-@item DIR_SEPARATOR
-If your system uses some character other than slash to separate
-directory names within a file specification, define this macro to be a C
-character constant specifying that character. When GCC displays file
-names, the character you specify will be used. GCC will test for
-both slash and the character you specify when parsing filenames.
-
-@findex DIR_SEPARATOR_2
-@item DIR_SEPARATOR_2
-If your system uses an alternative character other than
-@samp{DIR_SEPARATOR} to separate directory names within a file
-specification, define this macro to be a C character constant specifying
-that character. If you define this macro, GCC will test for slash,
-@samp{DIR_SEPARATOR}, and @samp{DIR_SEPARATOR_2} when parsing filenames.
-
-@findex TARGET_OBJECT_SUFFIX
-@item TARGET_OBJECT_SUFFIX
-Define this macro to be a C string representing the suffix for object
-files on your target machine. If you do not define this macro, GCC will
-use @samp{.o} as the suffix for object files.
-
-@findex TARGET_EXECUTABLE_SUFFIX
-@item TARGET_EXECUTABLE_SUFFIX
-Define this macro to be a C string representing the suffix to be
-automatically added to executable files on your target machine. If you
-do not define this macro, GCC will use the null string as the suffix for
-executable files.
-
-@findex HOST_OBJECT_SUFFIX
-@item HOST_OBJECT_SUFFIX
-Define this macro to be a C string representing the suffix for object
-files on your host machine (@samp{xm-*.h}). If you do not define this
-macro, GCC will use @samp{.o} as the suffix for object files.
+Define this macro if GCC should use the C implementation of @code{alloca}
+provided by @file{libiberty.a}. This only affects how some parts of the
+compiler itself allocate memory. It does not change code generation.
-@findex HOST_EXECUTABLE_SUFFIX
-@item HOST_EXECUTABLE_SUFFIX
-Define this macro to be a C string representing the suffix for
-executable files on your host machine (@samp{xm-*.h}). If you do not
-define this macro, GCC will use the null string as the suffix for
-executable files.
+When GCC is built with a compiler other than itself, the C @code{alloca}
+is always used. This is because most other implementations have serious
+bugs. You should define this macro only on a system where no
+stack-based @code{alloca} can possibly work. For instance, if a system
+has a small limit on the size of the stack, GCC's builtin @code{alloca}
+will not work reliably.
-@findex HOST_BIT_BUCKET
-@item HOST_BIT_BUCKET
-The name of a file or file-like object on the host system which acts as
-a ``bit bucket''. If you do not define this macro, GCC will use
-@samp{/dev/null} as the bit bucket. If the target does not support a
-bit bucket, this should be defined to the null string, or some other
-invalid filename. If the bit bucket is not writable, GCC will use a
-temporary file instead.
-
-@findex COLLECT_EXPORT_LIST
-@item COLLECT_EXPORT_LIST
-If defined, @code{collect2} will scan the individual object files
-specified on its command line and create an export list for the linker.
-Define this macro for systems like AIX, where the linker discards
-object files that are not referenced from @code{main} and uses export
-lists.
-
-@findex COLLECT2_HOST_INITIALIZATION
@item COLLECT2_HOST_INITIALIZATION
If defined, a C statement (sans semicolon) that performs host-dependent
initialization when @code{collect2} is being initialized.
-@findex GCC_DRIVER_HOST_INITIALIZATION
@item GCC_DRIVER_HOST_INITIALIZATION
If defined, a C statement (sans semicolon) that performs host-dependent
initialization when a compilation driver is being initialized.
-@findex UPDATE_PATH_HOST_CANONICALIZE
-@item UPDATE_PATH_HOST_CANONICALIZE (@var{path})
-If defined, a C statement (sans semicolon) that performs host-dependent
-canonicalization when a path used in a compilation driver or
-preprocessor is canonicalized. @var{path} is a malloc-ed path to be
-canonicalized. If the C statement does canonicalize @var{path} into a
-different buffer, the old path should be freed and the new buffer should
-have been allocated with malloc.
-@end table
+@item HOST_LONG_LONG_FORMAT
+If defined, the string used to indicate an argument of type @code{long
+long} to functions like @code{printf}. The default value is
+@code{"ll"}.
-@findex DUMPFILE_FORMAT
-@item DUMPFILE_FORMAT
-Define this macro to be a C string representing the format to use
-for constructing the index part of the dump file name on your host machine.
-If you do not define this macro, GCC will use @samp{.%02d.}. The full
-filename will be the prefix of the assembler file name concatenated with
-the string resulting from applying this format concatenated with a string
-unique to each dump file kind, e.g. @samp{rtl}.
-
-@findex bzero
-@findex bcmp
-In addition, configuration files for system V define @code{bcopy},
-@code{bzero} and @code{bcmp} as aliases. Some files define @code{alloca}
-as a macro when compiled with GCC, in order to take advantage of the
-benefit of GCC's built-in @code{alloca}.
+@item HOST_LONG_FORMAT
+If defined, the string used to indicate an argument of type @code{long}
+to functions like @code{printf}. The default value is @code{"l"}.
+
+@item HOST_PTR_PRINTF
+If defined, the string used to indicate an argument of type @code{void *}
+to functions like @code{printf}. The default value is @code{"%p"}.
+@end ftable
+
+In addition, if @command{configure} generates an incorrect definition of
+any of the macros in @file{auto-host.h}, you can override that
+definition in a host configuration header. If you need to do this,
+first see if it is possible to fix @command{configure}.
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