invoke.texi: Document -print-multiarch.

2012-11-14  Matthias Klose  <doko@ubuntu.com>

        * doc/invoke.texi: Document -print-multiarch.
        * doc/install.texi: Document --enable-multiarch.
        * doc/fragments.texi: Document MULTILIB_OSDIRNAMES, MULTIARCH_DIRNAME.
        * configure.ac: Add --enable-multiarch option.
        * configure: Regenerate.
        * Makefile.in (s-mlib): Pass MULTIARCH_DIRNAME to genmultilib.
        enable_multiarch, with_float: New macros.
        if_multiarch: New macro, define in terms of enable_multiarch.
        * genmultilib: Add new argument for the multiarch name.
        * gcc.c (multiarch_dir): Define.
        (for_each_path): Search for multiarch suffixes.
        (driver_handle_option): Handle multiarch option.
        (do_spec_1): Pass -imultiarch if defined.
        (main): Print multiarch.
        (set_multilib_dir): Separate multilib and multiarch names
        from multilib_select.
        (print_multilib_info): Ignore multiarch names in multilib_select.
        * incpath.c (add_standard_paths): Search the multiarch include dirs.
        * cppdefault.h (default_include): Document multiarch in multilib
        member.
        * cppdefault.c: [LOCAL_INCLUDE_DIR, STANDARD_INCLUDE_DIR] Add an
        include directory for multiarch directories.
        * common.opt: New options --print-multiarch and -imultilib.
        * config.gcc <i[34567]86-*-linux* | x86_64-*-linux*> (tmake_file):
        Include i386/t-linux.
        <i[34567]86-*-kfreebsd*-gnu | x86_64-*-kfreebsd*-gnu> (tmake_file):
        Include i386/t-kfreebsd.
        <i[34567]86-*-gnu*> (tmake_file): Include i386/t-gnu.
        * config/i386/t-linux64: Add multiarch names in
        MULTILIB_OSDIRNAMES, define MULTIARCH_DIRNAME.
        * config/i386/t-gnu: New file.
        * config/i386/t-kfreebsd: Likewise.
        * config/i386/t-linux: Likewise.

From-SVN: r193508

3 files changed, 74 insertions, 0 deletions

diff --git a/gcc/doc/fragments.texi b/gcc/doc/fragments.texi
index f53df29..28cef68 100644
--- a/gcc/doc/fragments.texi
+++ b/gcc/doc/fragments.texi
@@ -93,6 +93,12 @@ Write one element in @code{MULTILIB_DIRNAMES} for each element in
 default value will be @code{MULTILIB_OPTIONS}, with all slashes treated
 as spaces.
 
+@code{MULTILIB_DIRNAMES} describes the multilib directories using GCC
+conventions and is applied to directories that are part of the GCC
+installation.  When multilib-enabled, the compiler will add a
+subdirectory of the form @var{prefix}/@var{multilib} before each
+directory in the search path for libraries and crt files.
+
 For example, if @code{MULTILIB_OPTIONS} is set to @samp{m68000/m68020
 msoft-float}, then the default value of @code{MULTILIB_DIRNAMES} is
 @samp{m68000 m68020 msoft-float}.  You may specify a different value if
@@ -152,6 +158,60 @@ compiler.  In that case, set @code{MULTILIB_EXTRA_OPTS} to be the list
 of options to be used for all builds.  If you set this, you should
 probably set @code{CRTSTUFF_T_CFLAGS} to a dash followed by it.
 
+@findex MULTILIB_OSDIRNAMES
+@item MULTILIB_OSDIRNAMES
+If @code{MULTILIB_OPTIONS} is used, this variable specifies 
+a list of subdirectory names, that are used to modify the search
+path depending on the chosen multilib.  Unlike @code{MULTILIB_DIRNAMES},
+@code{MULTILIB_OSDIRNAMES} describes the multilib directories using
+operating systems conventions, and is applied to the directories such as
+@code{lib} or those in the @env{LIBRARY_PATH} environment variable.
+The format is either the same as of
+@code{MULTILIB_DIRNAMES}, or a set of mappings.  When it is the same
+as @code{MULTILIB_DIRNAMES}, it describes the multilib directories
+using operating system conventions, rather than GCC conventions.  When it is a set
+of mappings of the form @var{gccdir}=@var{osdir}, the left side gives
+the GCC convention and the right gives the equivalent OS defined
+location.  If the @var{osdir} part begins with a @samp{!},
+GCC will not search in the non-multilib directory and use
+exclusively the multilib directory.  Otherwise, the compiler will
+examine the search path for libraries and crt files twice; the first
+time it will add @var{multilib} to each directory in the search path,
+the second it will not.
+
+For configurations that support both multilib and multiarch,
+@code{MULTILIB_OSDIRNAMES} also encodes the multiarch name, thus
+subsuming @code{MULTIARCH_DIRNAME}.  The multiarch name is appended to
+each directory name, separated by a colon (e.g.
+@samp{../lib32:i386-linux-gnu}).
+
+Each multiarch subdirectory will be searched before the corresponding OS
+multilib directory, for example @samp{/lib/i386-linux-gnu} before
+@samp{/lib/../lib32}.  The multiarch name will also be used to modify the
+system header search path, as explained for @code{MULTIARCH_DIRNAME}.
+
+@findex MULTIARCH_DIRNAME
+@item MULTIARCH_DIRNAME
+This variable specifies the multiarch name for configurations that are
+multiarch-enabled but not multilibbed configurations.
+
+The multiarch name is used to augment the search path for libraries, crt
+files and system header files with additional locations.  The compiler
+will add a multiarch subdirectory of the form
+@var{prefix}/@var{multiarch} before each directory in the library and
+crt search path.  It will also add two directories
+@code{LOCAL_INCLUDE_DIR}/@var{multiarch} and
+@code{NATIVE_SYSTEM_HEADER_DIR}/@var{multiarch}) to the system header
+search path, respectively before @code{LOCAL_INCLUDE_DIR} and
+@code{NATIVE_SYSTEM_HEADER_DIR}.
+
+@code{MULTIARCH_DIRNAME} is not used for configurations that support
+both multilib and multiarch.  In that case, multiarch names are encoded
+in @code{MULTILIB_OSDIRNAMES} instead.
+
+More documentation about multiarch can be found at
+@uref{http://wiki.debian.org/Multiarch}.
+
 @findex SPECS
 @item SPECS
 Unfortunately, setting @code{MULTILIB_EXTRA_OPTS} is not enough, since
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index f158eb2..7396158 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1033,6 +1033,15 @@ libraries to support different target variants, calling
 conventions, etc.@: should not be built.  The default is to build a
 predefined set of them.
 
+@item --enable-multiarch
+Specify whether to enable or disable multiarch support.  The default is
+to check for glibc start files in a multiarch location, and enable it
+if the files are found.  The auto detection is enabled for native builds,
+and for cross builds configured with @option{--with-sysroot}, and without
+@option{--with-native-system-header-dir}.
+More documentation about multiarch can be found at
+@uref{http://wiki.debian.org/Multiarch}.
+
 Some targets provide finer-grained control over which multilibs are built
 (e.g., @option{--disable-softfloat}):
 @table @code
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 6f03a55..e019e3d 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -6336,6 +6336,11 @@ sibling directories this prints e.g.@: @file{../lib64}, @file{../lib} or
 @file{../lib32}, or if OS libraries are present in @file{lib/@var{subdir}}
 subdirectories it prints e.g.@: @file{amd64}, @file{sparcv9} or @file{ev6}.
 
+@item -print-multiarch
+@opindex print-multiarch
+Print the path to OS libraries for the selected multiarch,
+relative to some @file{lib} subdirectory.
+
 @item -print-prog-name=@var{program}
 @opindex print-prog-name
 Like @option{-print-file-name}, but searches for a program such as @samp{cpp}.