[RFC] Add configuration support for additional executable/library directories

Index: gcc/doc/install.texi
===================================================================
--- gcc/doc/install.texi	(revision 188026)
+++ gcc/doc/install.texi	(working copy)
@@ -767,6 +767,44 @@  from the full GCC manuals, which are pro
 are derived by an automatic conversion process from parts of the full
 manual.)
 
+@item --with-extra-prefix=@var{prefix}
+Specify an additional prefix for finding executables, libraries, and
+startfiles when the compiler is run.  By default no extra
+prefixes are used.  This option sets the options
+@option{--with-extra-exec-prefix=},
+@option{--with-extra-startfiles-prefix=},
+and @option{--with-extra-rpath-prefix=} if they are not specified.
+
+@item --with-extra-exec-prefix=@var{prefixes}
+Specify additional prefixes for finding executables when the compiler
+is run.  Each prefix is separated by the standard path sepator
+(usually colon, @option{:}).  By default no extra prefixes are used.
+
+@item --with-extra-startfile-prefix=@var{prefixes}
+Specify additional prefixes for finding libraries, and startfiles when
+the compiler is run.  Each prefix is separated by the standard path
+sepator (usually colon, @option{:}).  By default no extra prefixes are
+used.
+
+On powerpc64-linux systems, the dynamic linker will be searched for in
+the directories specified by the prefixed, that is used instead of the
+standard system dynamic linker.
+
+In addition on powerpc64-linux systems, if the user used static
+linking, as well as the @option{-mcpu=} option, the linker will be
+told to search in appropriate directories for libraries that are built
+for that particular machine.  If dynamic linking is used, these cpu
+tuned libraries will not be searched, since the dynamic linker will
+load the appropriate cpu tuned library, based on the system that is
+executing the code.
+
+@item --with-extra-rpath-prefix=@var{prefixes}
+Specify additional directories for finding shared libraries when
+the compiler is run.  Each prefix is separated by the standard path
+sepator (usually colon, @option{:}).  By default no extra prefixes are
+used.  If this option is used, each of the directories if they exist
+will be specified to the linker via the @option{-rpath=} option.
+
 @item --with-gxx-include-dir=@var{dirname}
 Specify
 the installation directory for G++ header files.  The default depends
Index: gcc/configure
===================================================================
--- gcc/configure	(revision 188026)
+++ gcc/configure	(working copy)
@@ -893,6 +893,10 @@  with_multilib_list
 enable_rpath
 with_libiconv_prefix
 enable_sjlj_exceptions
+with_extra_prefix
+with_extra_exec_prefix
+with_extra_startfile_prefix
+with_extra_rpath_prefix
 enable_secureplt
 enable_leading_mingw64_underscores
 enable_cld
@@ -1660,6 +1664,18 @@  Optional Packages:
   --with-gnu-ld           assume the C compiler uses GNU ld default=no
   --with-libiconv-prefix[=DIR]  search for libiconv in DIR/include and DIR/lib
   --without-libiconv-prefix     don't search for libiconv in includedir and libdir
+  --with-extra-prefix={prefixes}
+                          Add extra prefixes to the list of locations to
+                          search for all files
+  --with-extra-exec-prefix={prefixes}
+                          Add extra prefixes to the list of locations to
+                          search for executables
+  --with-extra-startfile-prefix={prefix}
+                          Add extra prefixes to the list of locations to
+                          search for startfiles
+  --with-extra-rpath-prefix={prefixes}
+                          Specify prefixes to pass to the linker via
+                          -rpath=dir to locate shared libraries
   --with-pic              try to use only PIC/non-PIC objects [default=use
                           both]
   --with-gnu-ld           assume the C compiler uses GNU ld [default=no]
@@ -11507,6 +11523,78 @@  case "$LIBINTL" in *$LIBICONV*)
 	LIBICONV= ;;
 esac
 
+
+# Check whether --with-extra-prefix was given.
+if test "${with_extra_prefix+set}" = set; then :
+  withval=$with_extra_prefix; EXTRA_PREFIX="$withval"
+else
+  EXTRA_PREFIX=''
+fi
+
+
+
+# Check whether --with-extra-exec-prefix was given.
+if test "${with_extra_exec_prefix+set}" = set; then :
+  withval=$with_extra_exec_prefix; EXTRA_EXEC_PREFIX="$withval"
+else
+  if test x"${EXTRA_PREFIX}" != x; then
+    EXTRA_EXEC_PREFIX="`echo ${EXTRA_PREFIX} | sed 's/:/\\/bin:/g'`/bin"
+  else
+    EXTRA_EXEC_PREFIX=""
+  fi
+fi
+
+
+if test x"${EXTRA_EXEC_PREFIX}" != x; then
+
+cat >>confdefs.h <<_ACEOF
+#define CONFIGURE_EXEC_PREFIX "$EXTRA_EXEC_PREFIX"
+_ACEOF
+
+fi
+
+
+# Check whether --with-extra-startfile-prefix was given.
+if test "${with_extra_startfile_prefix+set}" = set; then :
+  withval=$with_extra_startfile_prefix; EXTRA_STARTFILE_PREFIX="$withval"
+else
+  if test x"${EXTRA_PREFIX}" != x; then
+    EXTRA_STARTFILE_PREFIX="`echo ${EXTRA_PREFIX} | sed 's/:/\\/lib:/g'`/lib"
+  else
+    EXTRA_STARTFILE_PREFIX=""
+  fi
+fi
+
+
+if test x"${EXTRA_STARTFILE_PREFIX}" != x; then
+
+cat >>confdefs.h <<_ACEOF
+#define CONFIGURE_STARTFILE_PREFIX "$EXTRA_STARTFILE_PREFIX"
+_ACEOF
+
+fi
+
+
+# Check whether --with-extra-rpath-prefix was given.
+if test "${with_extra_rpath_prefix+set}" = set; then :
+  withval=$with_extra_rpath_prefix; EXTRA_RPATH_PREFIX="$withval"
+else
+  if test x"${EXTRA_PREFIX}" != x; then
+    EXTRA_RPATH_PREFIX="${prefix}/lib:`echo ${EXTRA_PREFIX} | sed 's/:/\\/lib:/g'`/lib"
+  else
+    EXTRA_RPATH_PREFIX=""
+  fi
+fi
+
+
+if test x"${EXTRA_RPATH_PREFIX}" != x; then
+
+cat >>confdefs.h <<_ACEOF
+#define CONFIGURE_RPATH_PREFIX "$EXTRA_RPATH_PREFIX"
+_ACEOF
+
+fi
+
 # Check whether --enable-secureplt was given.
 if test "${enable_secureplt+set}" = set; then :
   enableval=$enable_secureplt;
@@ -17967,7 +18055,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 17970 "configure"
+#line 18058 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18073,7 +18161,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18076 "configure"
+#line 18164 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
Index: gcc/gcc.c
===================================================================
--- gcc/gcc.c	(revision 188026)
+++ gcc/gcc.c	(working copy)
@@ -202,6 +202,8 @@  static int access_check (const char *, i
 static char *find_a_file (const struct path_prefix *, const char *, int, bool);
 static void add_prefix (struct path_prefix *, const char *, const char *,
 			int, int, int);
+static void add_multiple_prefix (struct path_prefix *, const char *,
+				 const char *, int, int, int);
 static void add_sysrooted_prefix (struct path_prefix *, const char *,
 				  const char *, int, int, int);
 static char *skip_whitespace (char *);
@@ -261,12 +263,15 @@  static const char *remove_outfile_spec_f
 static const char *version_compare_spec_function (int, const char **);
 static const char *include_spec_function (int, const char **);
 static const char *find_file_spec_function (int, const char **);
+static const char *find_dynamic_linker_spec_function (int, const char **);
 static const char *find_plugindir_spec_function (int, const char **);
 static const char *print_asm_header_spec_function (int, const char **);
 static const char *compare_debug_dump_opt_spec_function (int, const char **);
 static const char *compare_debug_self_opt_spec_function (int, const char **);
 static const char *compare_debug_auxbase_opt_spec_function (int, const char **);
 static const char *pass_through_libs_spec_func (int, const char **);
+static const char *extra_rpath_dirs_spec_function (int, const char **);
+const char *extra_cpu_dirs_spec_function (int, const char **);
 
 /* The Specs Language
 
@@ -656,6 +661,16 @@  proper position among the other output f
 #endif
 
 
+#ifndef LINK_RPATH_DIRS_SPEC
+#ifdef CONFIGURE_RPATH_PREFIX
+/* Add extra -rpath= options if configured.  */
+#define LINK_RPATH_DIRS_SPEC \
+  "%{!nostdlib:%{!nodefaultlibs:%{!static: %:extra-rpath-dirs()}}}"
+#else
+#define LINK_RPATH_DIRS_SPEC
+#endif
+#endif
+
 /* -u* was put back because both BSD and SysV seem to support it.  */
 /* %{static:} simply prevents an error message if the target machine
    doesn't handle -static.  */
@@ -669,6 +684,7 @@  proper position among the other output f
 #define LINK_COMMAND_SPEC "\
 %{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
     %(linker) " \
+    LINK_RPATH_DIRS_SPEC \
     LINK_PLUGIN_SPEC \
     "%{flto|flto=*:%<fcompare-debug*} \
     %{flto} %{flto=*} %l " LINK_PIE_SPEC \
@@ -1102,6 +1118,14 @@  static const char *gcc_libexec_prefix;
 #define STANDARD_STARTFILE_PREFIX_2 "/usr/lib/"
 #endif
 
+/* Additional directories added at configure time.  */
+#ifndef CONFIGURE_STARTFILE_PREFIX
+#define CONFIGURE_STARTFILE_PREFIX ""
+#endif
+#ifndef CONFIGURE_EXEC_PREFIX
+#define CONFIGURE_EXEC_PREFIX ""
+#endif
+
 #ifdef CROSS_DIRECTORY_STRUCTURE  /* Don't use these prefixes for a cross compiler.  */
 #undef MD_EXEC_PREFIX
 #undef MD_STARTFILE_PREFIX
@@ -1140,6 +1164,10 @@  static const char *const standard_startf
   = STANDARD_STARTFILE_PREFIX_1;
 static const char *const standard_startfile_prefix_2
   = STANDARD_STARTFILE_PREFIX_2;
+static const char *const configure_startfile_prefix
+  = CONFIGURE_STARTFILE_PREFIX;
+static const char *const configure_exec_prefix
+  = CONFIGURE_EXEC_PREFIX;
 
 /* A relative path to be used in finding the location of tools
    relative to the driver.  */
@@ -1255,12 +1283,15 @@  static const struct spec_function static
   { "version-compare",		version_compare_spec_function },
   { "include",			include_spec_function },
   { "find-file",		find_file_spec_function },
+  { "find-dynamic-linker",	find_dynamic_linker_spec_function },
   { "find-plugindir",		find_plugindir_spec_function },
   { "print-asm-header",		print_asm_header_spec_function },
   { "compare-debug-dump-opt",	compare_debug_dump_opt_spec_function },
   { "compare-debug-self-opt",	compare_debug_self_opt_spec_function },
   { "compare-debug-auxbase-opt", compare_debug_auxbase_opt_spec_function },
   { "pass-through-libs",	pass_through_libs_spec_func },
+  { "extra-rpath-dirs",		extra_rpath_dirs_spec_function },
+  { "extra-cpu-dirs",		extra_cpu_dirs_spec_function },
 #ifdef EXTRA_SPEC_FUNCTIONS
   EXTRA_SPEC_FUNCTIONS
 #endif
@@ -2439,6 +2470,44 @@  add_prefix (struct path_prefix *pprefix,
   (*prev) = pl;
 }
 
+/* Same as add_prefix, but split the prefix at each PATH_SEPARATOR.  */
+static void
+add_multiple_prefix (struct path_prefix *pprefix, const char *prefix,
+		     const char *component,
+		     /* enum prefix_priority */ int priority,
+		     int require_machine_suffix, int os_multilib)
+{
+  const char *startp, *endp;
+  char *nstore = (char *) alloca (strlen (prefix) + 3);
+
+  startp = endp = prefix;
+  while (1)
+    {
+      if (*endp == PATH_SEPARATOR || *endp == 0)
+	{
+	  strncpy (nstore, startp, endp - startp);
+	  if (endp == startp)
+	    strcpy (nstore, concat (".", dir_separator_str, NULL));
+	  else if (!IS_DIR_SEPARATOR (endp[-1]))
+	    {
+	      nstore[endp - startp] = DIR_SEPARATOR;
+	      nstore[endp - startp + 1] = 0;
+	    }
+	  else
+	    nstore[endp - startp] = 0;
+	  add_prefix (pprefix, nstore, component, priority,
+		      require_machine_suffix, os_multilib);
+	  if (*endp == 0)
+	    break;
+	  endp = startp = endp + 1;
+	}
+      else
+	endp++;
+    }
+
+  return;
+}
+
 /* Same as add_prefix, but prepending target_system_root to prefix.  */
 /* The target_system_root prefix has been relocated by gcc_exec_prefix.  */
 static void
@@ -3672,101 +3741,22 @@  process_command (unsigned int decoded_op
   temp = getenv ("COMPILER_PATH");
   if (temp)
     {
-      const char *startp, *endp;
-      char *nstore = (char *) alloca (strlen (temp) + 3);
-
-      startp = endp = temp;
-      while (1)
-	{
-	  if (*endp == PATH_SEPARATOR || *endp == 0)
-	    {
-	      strncpy (nstore, startp, endp - startp);
-	      if (endp == startp)
-		strcpy (nstore, concat (".", dir_separator_str, NULL));
-	      else if (!IS_DIR_SEPARATOR (endp[-1]))
-		{
-		  nstore[endp - startp] = DIR_SEPARATOR;
-		  nstore[endp - startp + 1] = 0;
-		}
-	      else
-		nstore[endp - startp] = 0;
-	      add_prefix (&exec_prefixes, nstore, 0,
-			  PREFIX_PRIORITY_LAST, 0, 0);
-	      add_prefix (&include_prefixes, nstore, 0,
-			  PREFIX_PRIORITY_LAST, 0, 0);
-	      if (*endp == 0)
-		break;
-	      endp = startp = endp + 1;
-	    }
-	  else
-	    endp++;
-	}
+      add_multiple_prefix (&exec_prefixes, temp, 0,
+			   PREFIX_PRIORITY_LAST, 0, 0);
+      add_multiple_prefix (&include_prefixes, temp, 0,
+			   PREFIX_PRIORITY_LAST, 0, 0);
     }
 
   temp = getenv (LIBRARY_PATH_ENV);
   if (temp && *cross_compile == '0')
-    {
-      const char *startp, *endp;
-      char *nstore = (char *) alloca (strlen (temp) + 3);
-
-      startp = endp = temp;
-      while (1)
-	{
-	  if (*endp == PATH_SEPARATOR || *endp == 0)
-	    {
-	      strncpy (nstore, startp, endp - startp);
-	      if (endp == startp)
-		strcpy (nstore, concat (".", dir_separator_str, NULL));
-	      else if (!IS_DIR_SEPARATOR (endp[-1]))
-		{
-		  nstore[endp - startp] = DIR_SEPARATOR;
-		  nstore[endp - startp + 1] = 0;
-		}
-	      else
-		nstore[endp - startp] = 0;
-	      add_prefix (&startfile_prefixes, nstore, NULL,
-			  PREFIX_PRIORITY_LAST, 0, 1);
-	      if (*endp == 0)
-		break;
-	      endp = startp = endp + 1;
-	    }
-	  else
-	    endp++;
-	}
-    }
+    add_multiple_prefix (&startfile_prefixes, temp, NULL,
+			 PREFIX_PRIORITY_LAST, 0, 1);
 
   /* Use LPATH like LIBRARY_PATH (for the CMU build program).  */
   temp = getenv ("LPATH");
   if (temp && *cross_compile == '0')
-    {
-      const char *startp, *endp;
-      char *nstore = (char *) alloca (strlen (temp) + 3);
-
-      startp = endp = temp;
-      while (1)
-	{
-	  if (*endp == PATH_SEPARATOR || *endp == 0)
-	    {
-	      strncpy (nstore, startp, endp - startp);
-	      if (endp == startp)
-		strcpy (nstore, concat (".", dir_separator_str, NULL));
-	      else if (!IS_DIR_SEPARATOR (endp[-1]))
-		{
-		  nstore[endp - startp] = DIR_SEPARATOR;
-		  nstore[endp - startp + 1] = 0;
-		}
-	      else
-		nstore[endp - startp] = 0;
-	      add_prefix (&startfile_prefixes, nstore, NULL,
-			  PREFIX_PRIORITY_LAST, 0, 1);
-	      if (*endp == 0)
-		break;
-	      endp = startp = endp + 1;
-	    }
-	  else
-	    endp++;
-	}
-    }
+    add_multiple_prefix (&startfile_prefixes, temp, NULL,
+			 PREFIX_PRIORITY_LAST, 0, 1);
 
   /* Process the options and store input files and switches in their
      vectors.  */
@@ -3942,6 +3932,16 @@  process_command (unsigned int decoded_op
     }
 #endif
 
+  /* Add prefixes specified by configure's --with-prefix.  */
+  if (*configure_exec_prefix)
+    add_multiple_prefix (&exec_prefixes, configure_exec_prefix, "GCC",
+			 PREFIX_PRIORITY_LAST, 0, 0);
+
+
+  if (*configure_startfile_prefix)
+    add_multiple_prefix (&startfile_prefixes, configure_startfile_prefix,
+			 "GCC", PREFIX_PRIORITY_LAST, 0, 1);
+
   /* More prefixes are enabled in main, after we read the specs file
      and determine whether this is cross-compilation or not.  */
 
@@ -8085,7 +8085,6 @@  find_file_spec_function (int argc, const
   return file;
 }
 
-
 /* %:find-plugindir spec function.  This function replaces its argument
     by the -iplugindir=<dir> option.  `dir' is found through find_file, that
     is the -print-file-name gcc program option. */
@@ -8340,3 +8339,208 @@  pass_through_libs_spec_func (int argc, c
     }
   return prepended;
 }
+
+#define IS_STD_DIR(PATH,STD) (strncmp (PATH, STD, sizeof (STD)-1) == 0)
+
+#ifdef CONFIGURE_RPATH_PREFIX
+
+static const char config_rpath[] = CONFIGURE_RPATH_PREFIX;
+
+/* Common code for extra_rpath_dirs_spec_function and
+   extra_cpu_dirs_spec_function to build up a list of -rpath=<dir> or -L<dir>
+   options, based on the extra rpath directories that were configured in.  */
+
+static char *
+build_rpath_or_cpu_dirs (const char *rpath_dirs,
+			 const char *prefix,
+			 const char *subdir)
+{
+  char *ret = NULL;
+  char *tmpstr, *endp, *prev_dir;
+  size_t rpath_len = strlen (rpath_dirs);
+  size_t subdir_len = (subdir) ? strlen (subdir) : 0;
+  size_t mlib_len = (multilib_os_dir) ? strlen (multilib_os_dir) : 0;
+  bool mlib_updir;
+  size_t i;
+
+  mlib_updir = (DIR_SEPARATOR == '/'
+		&& mlib_len > sizeof ("../") - 1
+		&& multilib_os_dir[0] == '.'
+		&& multilib_os_dir[1] == '.'
+		&& multilib_os_dir[2] == '/');
+
+  endp = tmpstr = XALLOCAVEC (char, rpath_len + subdir_len + mlib_len + 4);
+  prev_dir = NULL;
+  for (i = 0; i <= rpath_len; i++)
+    {
+      int ch = rpath_dirs[i];
+      if (ch != PATH_SEPARATOR && ch != '\0')
+	{
+	  *endp++ = ch;
+	  if (ch == DIR_SEPARATOR)
+	    prev_dir = endp;
+	}
+      else if (endp > tmpstr)
+	{
+	  /* Add current multlib directory.  Convert <stuff>/lib/../lib64 into
+	     <stuff>/lib64.  */
+	  if (mlib_len > 0)
+	    {
+	      if (mlib_updir && prev_dir)
+		{
+		  memcpy (prev_dir, multilib_os_dir + 3, mlib_len - 3);
+		  endp = prev_dir + mlib_len - 3;
+		}
+	      else
+		{
+		  *endp = DIR_SEPARATOR;
+		  memcpy (endp+1, multilib_os_dir, mlib_len);
+		  endp += mlib_len + 1;
+		}
+	    }
+
+	  /* Look for machine specific subdir?  */
+	  if (subdir)
+	    {
+	      *endp = DIR_SEPARATOR;
+	      memcpy (endp+1, subdir, subdir_len);
+	      endp += subdir_len + 1;
+	    }
+
+	  endp[0] = DIR_SEPARATOR;
+	  endp[1] = '.';
+	  endp[2] = '\0';
+
+	  if (is_directory (tmpstr, false))
+	    {
+	      *endp = '\0';
+	      if (ret)
+		ret = reconcat (ret, ret, " ", prefix, tmpstr, NULL);
+	      else
+		ret = concat (prefix, tmpstr, NULL);
+	    }
+
+	  endp = tmpstr;
+	}
+    }
+
+  return ret;
+}
+
+/* %:extra-rpath-dirs spec function.  If we have alternate rpath directories
+    (install lib directory + alternate startfile prefix directories), build a
+    string with all of the directories that are found with appropriate -rpath
+    options for the linker.  If the LD_RUN_PATH environment variable is
+    specified, include this into the -rpath arguments, since LD_RUN_PATH is
+    only used if -rpath is not specified.  */
+
+static const char *
+extra_rpath_dirs_spec_function (int argc, const char **argv ATTRIBUTE_UNUSED)
+{
+  static const char path_sep[2] = { PATH_SEPARATOR, '\0' };
+  const char *ld_run_path = getenv ("LD_RUN_PATH");
+  const char *ret;
+
+  if (argc != 0)
+    abort ();
+
+  if (ld_run_path)
+    {
+      char *new_rpath = concat (config_rpath, path_sep, ld_run_path, NULL);
+      ret = build_rpath_or_cpu_dirs (new_rpath, "-rpath=", NULL);
+      free (new_rpath);
+    }
+  else
+    ret = build_rpath_or_cpu_dirs (config_rpath, "-rpath=", NULL);
+
+  return ret;
+}
+
+/* %:extra-cpu-dirs spec function.  If we have alternate rpath directories,
+    search them to see if there are subdirectories that hold the static
+    libraries built for a particular machines, and return appropriate -L<dir>
+    to those directories.  */
+
+const char *
+extra_cpu_dirs_spec_function (int argc, const char **argv)
+{
+  if (argc != 1)
+    abort ();
+
+  return build_rpath_or_cpu_dirs (config_rpath, "-L", argv[0]);
+}
+
+/* %:find-dynamic-linker spec function.  Find the dynamic linker if we have
+    extra search paths configured.  */
+
+static const char *
+find_dynamic_linker_spec_function (int argc, const char **argv)
+{
+  const char *file;
+  char *tmpstr;
+  char *endp;
+  char *prev_dir;
+  size_t len;
+  size_t i;
+  int ch;
+
+  if (argc < 1)
+    abort ();
+
+  file = argv[0];
+  len = strlen (file);
+  gcc_assert (file[0] == DIR_SEPARATOR);
+
+  endp = tmpstr = XALLOCAVEC (char, ARRAY_SIZE (config_rpath) + len + 1);
+  prev_dir = NULL;
+  for (i = 0; i <= ARRAY_SIZE (config_rpath); i++)
+    {
+      ch = config_rpath[i];
+      if (ch != PATH_SEPARATOR && ch != '\0')
+	{
+	  if (ch == DIR_SEPARATOR)
+	    prev_dir = endp;
+
+	  *endp++ = ch;
+	}
+      else if (endp > tmpstr)
+	{
+	  *endp = '\0';
+	  if (prev_dir && strncmp (prev_dir, "/lib", sizeof ("/lib")-1) == 0)
+	    endp = prev_dir;
+	  memcpy (endp, file, len);
+	  endp[len] = '\0';
+	  if (access (tmpstr, X_OK) == 0)
+	    return xstrdup (tmpstr);
+
+	  endp = tmpstr;
+	}
+    }
+
+  return xstrdup (file);
+}
+
+#else
+const char *
+extra_rpath_dirs_spec_function (int argc ATTRIBUTE_UNUSED,
+				const char **argv ATTRIBUTE_UNUSED)
+{
+  return NULL;
+}
+
+const char *
+extra_cpu_dirs_spec_function (int argc ATTRIBUTE_UNUSED,
+			      const char **argv ATTRIBUTE_UNUSED)
+{
+  return NULL;
+}
+
+static const char *
+find_dynamic_linker_spec_function (int argc, const char **argv)
+{
+  if (argc != 1)
+    abort ();
+
+  return xstrdup (argv[0]);
+}
+#endif
Index: gcc/gcc.h
===================================================================
--- gcc/gcc.h	(revision 188026)
+++ gcc/gcc.h	(working copy)
@@ -37,6 +37,7 @@  extern int do_spec (const char *);
 extern void record_temp_file (const char *, int, int);
 extern void pfatal_with_name (const char *) ATTRIBUTE_NORETURN;
 extern void set_input (const char *);
+extern const char *extra_cpu_dirs_spec_function (int, const char **);
 
 /* Spec files linked with gcc.c must provide definitions for these.  */
 
Index: gcc/config.in
===================================================================
--- gcc/config.in	(revision 188026)
+++ gcc/config.in	(working copy)
@@ -2023,3 +2023,20 @@ 
 #undef vfork
 #endif
 
+
+/* Define extra executable prefixes at configure time.  */
+#ifndef USED_FOR_TARGET
+#undef CONFIGURE_EXEC_PREFIX
+#endif
+
+
+/* Define extra startfile prefixes at configure time.  */
+#ifndef USED_FOR_TARGET
+#undef CONFIGURE_STARTFILE_PREFIX
+#endif
+
+
+/* Define extra rpath prefixes at configure time.  */
+#ifndef USED_FOR_TARGET
+#undef CONFIGURE_RPATH_PREFIX
+#endif
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac	(revision 188026)
+++ gcc/configure.ac	(working copy)
@@ -1585,6 +1585,57 @@  case "$LIBINTL" in *$LIBICONV*)
 	LIBICONV= ;;
 esac
 
+AC_ARG_WITH([extra-prefix],
+[AC_HELP_STRING([--with-extra-prefix={prefixes}],
+ [Add extra prefixes to the list of locations to search for all files])],
+ [EXTRA_PREFIX="$withval"],
+ [EXTRA_PREFIX=''])
+
+AC_ARG_WITH([extra-exec-prefix],
+[AC_HELP_STRING([--with-extra-exec-prefix={prefixes}],
+ [Add extra prefixes to the list of locations to search for executables])],
+ [EXTRA_EXEC_PREFIX="$withval"],
+ [if test x"${EXTRA_PREFIX}" != x; then
+    EXTRA_EXEC_PREFIX="`echo ${EXTRA_PREFIX} | sed 's/:/\\/bin:/g'`/bin"
+  else
+    EXTRA_EXEC_PREFIX=""
+  fi])
+
+if test x"${EXTRA_EXEC_PREFIX}" != x; then
+  AC_DEFINE_UNQUOTED(CONFIGURE_EXEC_PREFIX, "$EXTRA_EXEC_PREFIX",
+		     [Extra executable prefixes])
+fi
+
+AC_ARG_WITH([extra-startfile-prefix],
+[AC_HELP_STRING([--with-extra-startfile-prefix={prefix}],
+ [Add extra prefixes to the list of locations to search for startfiles])],
+ [EXTRA_STARTFILE_PREFIX="$withval"],
+ [if test x"${EXTRA_PREFIX}" != x; then
+    EXTRA_STARTFILE_PREFIX="`echo ${EXTRA_PREFIX} | sed 's/:/\\/lib:/g'`/lib"
+  else
+    EXTRA_STARTFILE_PREFIX=""
+  fi])
+
+if test x"${EXTRA_STARTFILE_PREFIX}" != x; then
+  AC_DEFINE_UNQUOTED(CONFIGURE_STARTFILE_PREFIX, "$EXTRA_STARTFILE_PREFIX",
+		     [Extra startfile prefix])
+fi
+
+AC_ARG_WITH([extra-rpath-prefix],
+[AC_HELP_STRING([--with-extra-rpath-prefix={prefixes}],
+ [Specify prefixes to pass to the linker via -rpath=dir to locate shared libraries])],
+ [EXTRA_RPATH_PREFIX="$withval"],
+ [if test x"${EXTRA_PREFIX}" != x; then
+    EXTRA_RPATH_PREFIX="${prefix}/lib:`echo ${EXTRA_PREFIX} | sed 's/:/\\/lib:/g'`/lib"
+  else
+    EXTRA_RPATH_PREFIX=""
+  fi])
+
+if test x"${EXTRA_RPATH_PREFIX}" != x; then
+  AC_DEFINE_UNQUOTED(CONFIGURE_RPATH_PREFIX, "$EXTRA_RPATH_PREFIX",
+		     [Extra rpath prefix])
+fi
+
 AC_ARG_ENABLE(secureplt,
 [AS_HELP_STRING([--enable-secureplt],
 		[enable -msecure-plt by default for PowerPC])],
Index: gcc/config/rs6000/x-rs6000
===================================================================
--- gcc/config/rs6000/x-rs6000	(revision 188026)
+++ gcc/config/rs6000/x-rs6000	(working copy)
@@ -1,3 +1,3 @@ 
 driver-rs6000.o : $(srcdir)/config/rs6000/driver-rs6000.c \
-  $(CONFIG_H) $(SYSTEM_H) $(TM_H) coretypes.h
+  $(CONFIG_H) $(SYSTEM_H) $(TM_H) coretypes.h $(GCC_H)
 	$(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $<
Index: gcc/config/rs6000/linux64.h
===================================================================
--- gcc/config/rs6000/linux64.h	(revision 188026)
+++ gcc/config/rs6000/linux64.h	(working copy)
@@ -1,7 +1,7 @@ 
 /* Definitions of target machine for GNU compiler,
    for 64 bit PowerPC linux.
    Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
-   2009, 2010, 2011  Free Software Foundation, Inc.
+   2009, 2010, 2011, 2012  Free Software Foundation, Inc.
 
    This file is part of GCC.
 
@@ -358,8 +358,14 @@  extern int dot_symbols;
 #undef	LINK_OS_DEFAULT_SPEC
 #define LINK_OS_DEFAULT_SPEC "%(link_os_linux)"
 
+#ifdef CONFIGURE_STARTFILE_PREFIX
+#define GLIBC_DYNAMIC_LINKER32 "%:find-dynamic-linker(/lib/ld.so.1)"
+#define GLIBC_DYNAMIC_LINKER64 "%:find-dynamic-linker(/lib64/ld64.so.1)"
+#else
 #define GLIBC_DYNAMIC_LINKER32 "/lib/ld.so.1"
 #define GLIBC_DYNAMIC_LINKER64 "/lib64/ld64.so.1"
+#endif
+
 #define UCLIBC_DYNAMIC_LINKER32 "/lib/ld-uClibc.so.0"
 #define UCLIBC_DYNAMIC_LINKER64 "/lib/ld64-uClibc.so.0"
 #if DEFAULT_LIBC == LIBC_UCLIBC
@@ -369,17 +375,39 @@  extern int dot_symbols;
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif
+
 #define GNU_USER_DYNAMIC_LINKER32 \
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32)
 #define GNU_USER_DYNAMIC_LINKER64 \
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64)
 
+#ifdef CONFIGURE_STARTFILE_PREFIX
+#ifdef HAVE_LOCAL_CPU_DETECT
+#define LINUX_EXTRA_STATIC_LIBDIRS64 \
+"%{static: \
+%{mcpu=native: %:linux_extra_static_libdirs(%:local_cpu_detect(cpu))} \
+%{!mcpu=native: %{mcpu=*: %:linux_extra_static_libdirs(%{mcpu=*}) }}} "
+
+#else
+#define LINUX_EXTRA_STATIC_LIBDIRS64 \
+"%{static: \
+%{mcpu=: %:linux_extra_static_libdirs(%{mcpu=*}) }} "
+#endif
+
+#else
+#define LINUX_EXTRA_STATIC_LIBDIRS64
+#endif
+
 
-#define LINK_OS_LINUX_SPEC32 "-m elf32ppclinux %{!shared: %{!static: \
+#define LINK_OS_LINUX_SPEC32 "-m elf32ppclinux " \
+LINUX_EXTRA_STATIC_LIBDIRS32 \
+"%{!shared: %{!static: \
   %{rdynamic:-export-dynamic} \
   -dynamic-linker " GNU_USER_DYNAMIC_LINKER32 "}}"
 
-#define LINK_OS_LINUX_SPEC64 "-m elf64ppc %{!shared: %{!static: \
+#define LINK_OS_LINUX_SPEC64 "-m elf64ppc " \
+LINUX_EXTRA_STATIC_LIBDIRS64 \
+"%{!shared: %{!static: \
   %{rdynamic:-export-dynamic} \
   -dynamic-linker " GNU_USER_DYNAMIC_LINKER64 "}}"
 
Index: gcc/config/rs6000/rs6000.h
===================================================================
--- gcc/config/rs6000/rs6000.h	(revision 188026)
+++ gcc/config/rs6000/rs6000.h	(working copy)
@@ -1,7 +1,7 @@ 
 /* Definitions of target machine for GNU compiler, for IBM RS/6000.
    Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
-   2010, 2011
+   2010, 2011, 2012
    Free Software Foundation, Inc.
    Contributed by Richard Kenner (kenner@vlsi1.ultra.nyu.edu)
 
@@ -206,15 +206,21 @@ 
 #if defined(__powerpc__) || defined(__POWERPC__) || defined(_AIX)
 /* In driver-rs6000.c.  */
 extern const char *host_detect_local_cpu (int argc, const char **argv);
-#define EXTRA_SPEC_FUNCTIONS \
+#define LOCAL_CPU_EXTRA_SPEC_FUNCTIONS \
   { "local_cpu_detect", host_detect_local_cpu },
 #define HAVE_LOCAL_CPU_DETECT
 #define ASM_CPU_NATIVE_SPEC "%:local_cpu_detect(asm)"
 
 #else
 #define ASM_CPU_NATIVE_SPEC "%(asm_default)"
+#define LOCAL_CPU_EXTR_SPEC_FUNCTIONS
 #endif
 
+#define SUBTARGET_EXTRA_SPEC_FUNCTIONS
+#define EXTRA_SPEC_FUNCTIONS						\
+  SUBTARGET_EXTRA_SPEC_FUNCTIONS					\
+  LOCAL_CPU_EXTRA_SPEC_FUNCTIONS
+
 #ifndef CC1_CPU_SPEC
 #ifdef HAVE_LOCAL_CPU_DETECT
 #define CC1_CPU_SPEC \
Index: gcc/config/rs6000/driver-rs6000.c
===================================================================
--- gcc/config/rs6000/driver-rs6000.c	(revision 188026)
+++ gcc/config/rs6000/driver-rs6000.c	(working copy)
@@ -1,5 +1,5 @@ 
 /* Subroutines for the gcc driver.
-   Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2008, 2009, 2012 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -22,6 +22,7 @@  along with GCC; see the file COPYING3.  
 #include "coretypes.h"
 #include "tm.h"
 #include <stdlib.h>
+#include "gcc.h"
 
 #ifdef _AIX
 # include <sys/systemcfg.h>
@@ -545,3 +546,32 @@  host_detect_local_cpu (int argc, const c
 
 #endif /* GCC_VERSION */
 
+
+#ifdef CONFIGURE_STARTFILE_PREFIX
+/* Add -L for all of the machine dependent directories found in the extra rpath
+   directories.  We don't need to do this for dynamic links, since the dynamic
+   linker will pick up the right library based on the machine that is currently
+   running.  */
+
+const char *
+rs6000_extra_static_libdirs (int argc, const char **argv)
+{
+  const char *new_argv[2];
+  const char *cpu;
+
+  if (argc == 1 && strncmp (argv[0], "mcpu=", sizeof ("-mcpu=")-1) == 0)
+    cpu = argv[0] + sizeof ("-mcpu=") - 1;
+
+  else if (argc == 2 && strcmp (argv[0], "-") == 0
+	   && strncmp (argv[1], "mcpu=", sizeof ("mcpu=")-1) == 0)
+    cpu = argv[1] + sizeof ("mcpu=") - 1;
+
+  else
+    abort ();
+
+  new_argv[0] = cpu;
+  new_argv[1] = NULL;
+  return extra_cpu_dirs_spec_function (1, new_argv);
+}
+
+#endif /* !CONFIGURE_STARTFILE_PREFIX */
Index: gcc/config/rs6000/sysv4.h
===================================================================
--- gcc/config/rs6000/sysv4.h	(revision 188026)
+++ gcc/config/rs6000/sysv4.h	(working copy)
@@ -792,7 +792,12 @@  extern int fixuplabelno;
 
 #define LINK_START_LINUX_SPEC ""
 
+#ifdef CONFIGURE_STARTFILE_PREFIX
+#define GLIBC_DYNAMIC_LINKER "%:find-dynamic-linker(/lib/ld.so.1)"
+#else
 #define GLIBC_DYNAMIC_LINKER "/lib/ld.so.1"
+#endif
+
 #define UCLIBC_DYNAMIC_LINKER "/lib/ld-uClibc.so.0"
 #if DEFAULT_LIBC == LIBC_UCLIBC
 #define CHOOSE_DYNAMIC_LINKER(G, U) "%{mglibc:" G ";:" U "}"
@@ -801,10 +806,30 @@  extern int fixuplabelno;
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif
+
 #define GNU_USER_DYNAMIC_LINKER \
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER)
 
-#define LINK_OS_LINUX_SPEC "-m elf32ppclinux %{!shared: %{!static: \
+#ifdef CONFIGURE_STARTFILE_PREFIX
+#ifdef HAVE_LOCAL_CPU_DETECT
+#define LINUX_EXTRA_STATIC_LIBDIRS32 \
+"%{static: \
+%{mcpu=native: %:linux_extra_static_libdirs(%:local_cpu_detect(cpu))} \
+%{!mcpu=native: %{mcpu=*: %:linux_extra_static_libdirs(%{mcpu=*}) }}} "
+
+#else
+#define LINUX_EXTRA_STATIC_LIBDIRS32 \
+"%{static: \
+%{mcpu=: %:linux_extra_static_libdirs(%{mcpu=*}) }} "
+#endif
+
+#else
+#define LINUX_EXTRA_STATIC_LIBDIRS32 ""
+#endif
+
+#define LINK_OS_LINUX_SPEC "-m elf32ppclinux " \
+LINUX_EXTRA_STATIC_LIBDIRS32 \
+"%{!shared: %{!static: \
   %{rdynamic:-export-dynamic} \
   -dynamic-linker " GNU_USER_DYNAMIC_LINKER "}}"
 
@@ -870,6 +895,22 @@  ncrtn.o%s"
 #define CPP_OS_OPENBSD_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_POSIX_THREADS}"
 #endif
 
+/* If we have additional startfiles, we want to use the dynamic linker from the
+   directories those startfiles are in.  We also want to set the -rpath for
+   those directories.
+
+   Also if this is a static link, see if we have any processor specific
+   directories in the extra startfiles directories.  We don't have to worry
+   about dynamic libraries, since the dynamic linker will include them
+   automatically. */
+#ifdef CONFIGURE_STARTFILE_PREFIX
+extern const char *rs6000_extra_static_libdirs (int argc, const char **argv);
+
+#undef SUBTARGET_EXTRA_SPEC_FUNCTIONS
+#define SUBTARGET_EXTRA_SPEC_FUNCTIONS \
+  { "linux_extra_static_libdirs",	rs6000_extra_static_libdirs },
+#endif
+
 /* Define any extra SPECS that the compiler needs to generate.  */
 /* Override rs6000.h definition.  */
 #undef	SUBTARGET_EXTRA_SPECS