[google] Enable both ld and gold in gcc (issue4664051)

[dougkwan at google dot com (Doug Kwan)]

This patch enables both ld and gold in gcc using the -fuse-ld switch.  The
original patch use written by Nick Clifton and was subsequently updated by
Matthias Klose.  The patch currently does not work with LTO but that is
okay for now and it is no worse than its counterpart in an older gcc version.
We need this functionality for now.  It is mostly used as a safety net in the
Android toolchain if gold does not work.  We can disable LTO in that case.
Hopefully we will fix this can resubmit it for trunk later.

This is tested by running ./buildit and building the Android toolchain.

I would like to apply this to goolge/main only.

2011-06-27   Doug Kwan  <dougkwan@google.com>

	Google ref 41164-p2
	Backport upstream patch under review.

	2011-01-19   Nick Clifton  <nickc@redhat.com>
       		     Matthias Klose <doko@debian.org>

		* configure.ac (gcc_cv_gold_srcdir): New cached variable -
		contains the location of the gold sources.
		(ORIGINAL_GOLD_FOR_TARGET): New substituted variable - contains
		the name of the locally built gold executable.
		* configure: Regenerate.
		* collect2.c (main): Detect the -use-gold and -use-ld switches
		and select the appropriate linker, if found.
		If a linker cannot be found and collect2 is executing in
		verbose mode then report the search paths examined.
		* exec-tool.in: Detect the -use-gold and -use-ld switches and
		select the appropriate linker, if found.
		Add support for -v switch.
		Report problems locating linker executable.
		* gcc.c (LINK_COMMAND_SPEC): Translate -fuse-ld=gold into
		-use-gold and -fuse-ld=bfd into -use-ld.
		* common.opt: Add fuse-ld=gold and fuse-ld=bfd.
		* opts.c (comman_handle_option): Ignore -fuse-ld=gold and
		-fuse-ld=bfd.
		* doc/invoke.texi: Document the new options.

Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 175346)
+++ gcc/doc/invoke.texi	(working copy)
@@ -418,7 +418,7 @@
 -funit-at-a-time -funroll-all-loops -funroll-loops @gol
 -funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
 -fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
--fwhole-program -fwpa -fuse-linker-plugin @gol
+-fwhole-program -fwpa -fuse-ld -fuse-linker-plugin @gol
 --param @var{name}=@var{value}
 -O  -O0  -O1  -O2  -O3  -Os -Ofast}
 
@@ -8017,6 +8017,16 @@
 
 Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
 
+@item -fuse-ld=gold
+Use the @command{gold} linker instead of the default linker.
+This option is only necessary if GCC has been configured with
+@option{--enable-gold} and @option{--enable-ld=default}.
+
+@item -fuse-ld=bfd
+Use the @command{ld.bfd} linker instead of the default linker.
+This option is only necessary if GCC has been configured with
+@option{--enable-gold} and @option{--enable-ld}.
+
 @item -fcprop-registers
 @opindex fcprop-registers
 After register allocation and post-register allocation instruction splitting,
Index: gcc/configure
===================================================================
--- gcc/configure	(revision 175346)
+++ gcc/configure	(working copy)
@@ -681,6 +681,7 @@
 gcc_cv_objdump
 ORIGINAL_NM_FOR_TARGET
 gcc_cv_nm
+ORIGINAL_GOLD_FOR_TARGET
 ORIGINAL_LD_FOR_TARGET
 ORIGINAL_PLUGIN_LD_FOR_TARGET
 gcc_cv_ld
@@ -21131,6 +21132,21 @@
 fi
 fi
 
+gcc_cv_ld_gold_srcdir=`echo $srcdir | sed -e 's,/gcc$,,'`/gold
+
+if test "${gcc_cv_gold+set}" = set; then :
+
+else
+
+if test -f $gcc_cv_ld_gold_srcdir/configure.ac \
+     && test -f ../gold/Makefile \
+     && test x$build = x$host; then
+	gcc_cv_gold=../gold/ld-new$build_exeext
+else
+        gcc_cv_gold=''
+fi
+fi
+
 ORIGINAL_PLUGIN_LD_FOR_TARGET=$gcc_cv_ld
 PLUGIN_LD=`basename $gcc_cv_ld`
 
@@ -21170,6 +21186,9 @@
  ;;
 esac
 
+ORIGINAL_GOLD_FOR_TARGET=$gcc_cv_gold
+
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking what linker to use" >&5
 $as_echo_n "checking what linker to use... " >&6; }
 if test "$gcc_cv_ld" = ../ld/ld-new$build_exeext; then
Index: gcc/gcc.c
===================================================================
--- gcc/gcc.c	(revision 175346)
+++ gcc/gcc.c	(working copy)
@@ -657,6 +657,9 @@
     }"PLUGIN_COND_CLOSE" \
     %{flto|flto=*:%<fcompare-debug*} \
     %{flto} %{flto=*} %l " LINK_PIE_SPEC \
+   "%{fuse-ld=gold:%{fuse-ld=bfd:%e-fuse-ld=gold and -fuse-ld=bfd may not be used together}} \
+    %{fuse-ld=gold:-use-gold} \
+    %{fuse-ld=bfd:-use-ld}" \
    "%X %{o*} %{e*} %{N} %{n} %{r}\
     %{s} %{t} %{u*} %{z} %{Z} %{!nostdlib:%{!nostartfiles:%S}}\
     %{static:} %{L*} %(mfwrap) %(link_libgcc) %o\
Index: gcc/opts.c
===================================================================
--- gcc/opts.c	(revision 175346)
+++ gcc/opts.c	(working copy)
@@ -1729,8 +1729,9 @@
       dc->max_errors = value;
       break;
 
+    case OPT_fuse_ld_:
     case OPT_fuse_linker_plugin:
-      /* No-op. Used by the driver and passed to us because it starts with f.*/
+      /* No-op. Used by the driver and passed to us because it starts with f.  */
       break;
 
     case OPT_Wuninitialized:
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac	(revision 175346)
+++ gcc/configure.ac	(working copy)
@@ -1974,6 +1974,17 @@
         AC_PATH_PROG(gcc_cv_ld, $LD_FOR_TARGET)
 fi])
 
+gcc_cv_ld_gold_srcdir=`echo $srcdir | sed -e 's,/gcc$,,'`/gold
+
+AS_VAR_SET_IF(gcc_cv_gold,, [
+if test -f $gcc_cv_ld_gold_srcdir/configure.ac \
+     && test -f ../gold/Makefile \
+     && test x$build = x$host; then
+	gcc_cv_gold=../gold/ld-new$build_exeext
+else
+        gcc_cv_gold=''
+fi])
+
 ORIGINAL_PLUGIN_LD_FOR_TARGET=$gcc_cv_ld
 PLUGIN_LD=`basename $gcc_cv_ld`
 AC_ARG_WITH(plugin-ld,
@@ -2003,6 +2014,9 @@
   *) AC_CONFIG_FILES(collect-ld:exec-tool.in, [chmod +x collect-ld]) ;;
 esac 
 
+ORIGINAL_GOLD_FOR_TARGET=$gcc_cv_gold
+AC_SUBST(ORIGINAL_GOLD_FOR_TARGET)
+
 AC_MSG_CHECKING(what linker to use)
 if test "$gcc_cv_ld" = ../ld/ld-new$build_exeext; then
 	# Single tree build which includes ld.  We want to prefer it
Index: gcc/exec-tool.in
===================================================================
--- gcc/exec-tool.in	(revision 175346)
+++ gcc/exec-tool.in	(working copy)
@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2007, 2008, 2010 Free Software Foundation, Inc.
+# Copyright (C) 2007, 2008, 2010, 2011 Free Software Foundation, Inc.
 # This file is part of GCC.
 
 # GCC is free software; you can redistribute it and/or modify
@@ -21,11 +21,13 @@
 
 ORIGINAL_AS_FOR_TARGET="@ORIGINAL_AS_FOR_TARGET@"
 ORIGINAL_LD_FOR_TARGET="@ORIGINAL_LD_FOR_TARGET@"
+ORIGINAL_GOLD_FOR_TARGET="@ORIGINAL_GOLD_FOR_TARGET@"
 ORIGINAL_PLUGIN_LD_FOR_TARGET="@ORIGINAL_PLUGIN_LD_FOR_TARGET@"
 ORIGINAL_NM_FOR_TARGET="@ORIGINAL_NM_FOR_TARGET@"
 exeext=@host_exeext@
 fast_install=@enable_fast_install@
 objdir=@objdir@
+version="1.1"
 
 invoked=`basename "$0"`
 id=$invoked
@@ -36,15 +38,44 @@
     dir=gas
     ;;
   collect-ld)
-    # when using a linker plugin, gcc will always pass '-plugin' as the
-    # first or second option to the linker.
-    if test x"$1" = "x-plugin" || test x"$2" = "x-plugin"; then
-      original=$ORIGINAL_PLUGIN_LD_FOR_TARGET
-    else
-      original=$ORIGINAL_LD_FOR_TARGET
+    prog=ld-new$exeext
+    # Look for the a command line option
+    # specifying the linker to be used.
+    case " $* " in
+      *\ -use-gold\ *)
+        original=$ORIGINAL_GOLD_FOR_TARGET
+	dir=gold
+        ;;
+      *\ -use-ld\ * | *\ -use-ld.bfd\ *)
+        original=$ORIGINAL_LD_FOR_TARGET
+        dir=ld
+        ;;
+      *\ -plugin\ *)
+        original=$ORIGINAL_PLUGIN_LD_FOR_TARGET
+        dir=ld
+	;;
+      *)
+        original=$ORIGINAL_LD_FOR_TARGET
+        dir=ld
+	;;
+    esac
+
+    # If the selected linker has not been configured then
+    # try using the others, in the order PLUGIN-LD, LD, GOLD.
+    if test x"$original" = x; then
+      if test x"$ORIGINAL_PLUGIN_LD_FOR_TARGET" != x; then
+        original=$ORIGINAL_PLUGIN_LD_FOR_TARGET
+        dir=ld
+      elif test x"$ORIGINAL_LD_FOR_TARGET" != x; then
+        original=$ORIGINAL_LD_FOR_TARGET
+        dir=ld
+      elif test x"$ORIGINAL_GOLD_FOR_TARGET" != x; then
+        original=$ORIGINAL_GOLD_FOR_TARGET
+        dir=gold
+      # Otherwise do nothing - the case statement below
+      # will issue an error message for us.
+      fi
     fi
-    prog=ld-new$exeext
-    dir=ld
     id=ld
     ;;
   nm)
@@ -61,29 +92,58 @@
     scriptdir=`cd "$tdir" && pwd`
 
     if test -x $scriptdir/../$dir/$prog; then
-      test "$fast_install" = yes || exec $scriptdir/../$dir/$prog ${1+"$@"}
+      if test "$fast_install" = yes; then
+        # If libtool did everything it needs to do, there's a fast path.
+        lt_prog=$scriptdir/../$dir/$objdir/lt-$prog 
 
-      # if libtool did everything it needs to do, there's a fast path
-      lt_prog=$scriptdir/../$dir/$objdir/lt-$prog 
-      test -x $lt_prog && exec $lt_prog ${1+"$@"}
-
-      # libtool has not relinked ld-new yet, but we cannot just use the
-      # previous stage (because then the relinking would just never happen!).
-      # So we take extra care to use prev-ld/ld-new *on recursive calls*.
-      eval LT_RCU="\${LT_RCU_$id}"
-      test x"$LT_RCU" = x"1" && exec $scriptdir/../prev-$dir/$prog ${1+"$@"}
-
-      eval LT_RCU_$id=1
-      export LT_RCU_$id
-      $scriptdir/../$dir/$prog ${1+"$@"}
-      result=$?
-      exit $result
-
+	if test -x $lt_prog; then
+	  original=$lt_prog
+        else
+          # Libtool has not relinked ld-new yet, but we cannot just use the
+          # previous stage (because then the relinking would just never happen!).
+          # So we take extra care to use prev-ld/ld-new *on recursive calls*.
+          eval LT_RCU="\${LT_RCU_$id}"
+          if test x"$LT_RCU" = x"1"; then
+	    original=$scriptdir/../prev-$dir/$prog
+          else
+            eval LT_RCU_$id=1
+            export LT_RCU_$id
+            case " $* " in
+              *\ -v\ *)
+               echo "$invoked $version"
+               echo $scriptdir/../$dir/$prog $*
+               ;;
+            esac
+            $scriptdir/../$dir/$prog ${1+"$@"}
+            result=$?
+            exit $result
+          fi
+        fi
+      else
+	original=$scriptdir/../$dir/$prog
+      fi
     else
-      exec $scriptdir/../prev-$dir/$prog ${1+"$@"}
+      original=$scriptdir/../prev-$dir/$prog
     fi
     ;;
-  *)
-    exec $original ${1+"$@"}
+  "")
+    echo "$invoked: executable not configured"
+    exit 1
     ;;
 esac
+
+# If -v has been used then display our version number
+# and then echo the command we are about to invoke.
+case " $* " in
+  *\ -v\ *)
+    echo "$invoked $version"
+    echo $original $*
+    ;;
+esac
+
+if test -x $original; then
+  exec "$original" ${1+"$@"}
+else
+  echo "$invoked: unable to locate executable: $original"
+  exit 1
+fi
Index: gcc/common.opt
===================================================================
--- gcc/common.opt	(revision 175346)
+++ gcc/common.opt	(working copy)
@@ -2138,6 +2138,9 @@
 Common Report Var(flag_unwind_tables) Optimization
 Just generate unwind tables for exception handling
 
+fuse-ld=
+Common Joined Undocumented
+
 fuse-linker-plugin
 Common Undocumented
 
Index: gcc/collect2.c
===================================================================
--- gcc/collect2.c	(revision 175346)
+++ gcc/collect2.c	(working copy)
@@ -1075,17 +1075,19 @@
 int
 main (int argc, char **argv)
 {
-  static const char *const ld_suffix	= "ld";
-  static const char *const plugin_ld_suffix = PLUGIN_LD;
-  static const char *const real_ld_suffix = "real-ld";
+  static const char *const ld_suffix	     = "ld";
+  static const char *const gold_suffix       = "ld.gold";
+  static const char *const bfd_ld_suffix     = "ld.bfd";
+  static const char *const plugin_ld_suffix  = PLUGIN_LD;
+  static const char *const real_ld_suffix    = "real-ld";
   static const char *const collect_ld_suffix = "collect-ld";
-  static const char *const nm_suffix	= "nm";
-  static const char *const gnm_suffix	= "gnm";
+  static const char *const nm_suffix	     = "nm";
+  static const char *const gnm_suffix	     = "gnm";
 #ifdef LDD_SUFFIX
-  static const char *const ldd_suffix	= LDD_SUFFIX;
+  static const char *const ldd_suffix	     = LDD_SUFFIX;
 #endif
-  static const char *const strip_suffix = "strip";
-  static const char *const gstrip_suffix = "gstrip";
+  static const char *const strip_suffix      = "strip";
+  static const char *const gstrip_suffix     = "gstrip";
 
 #ifdef CROSS_DIRECTORY_STRUCTURE
   /* If we look for a program in the compiler directories, we just use
@@ -1095,6 +1097,10 @@
 
   const char *const full_ld_suffix =
     concat(target_machine, "-", ld_suffix, NULL);
+  const char *const full_gold_suffix =
+    concat (target_machine, "-", gold_suffix, NULL);
+  const char *const full_bfd_ld_suffix =
+    concat (target_machine, "-", bfd_ld_suffix, NULL);
   const char *const full_plugin_ld_suffix =
     concat(target_machine, "-", plugin_ld_suffix, NULL);
   const char *const full_nm_suffix =
@@ -1110,15 +1116,17 @@
   const char *const full_gstrip_suffix =
     concat (target_machine, "-", gstrip_suffix, NULL);
 #else
-  const char *const full_ld_suffix	= ld_suffix;
+  const char *const full_ld_suffix	  = ld_suffix;
+  const char *const full_gold_suffix	  = gold_suffix;
+  const char *const full_bfd_ld_suffix	  = bfd_ld_suffix;
   const char *const full_plugin_ld_suffix = plugin_ld_suffix;
-  const char *const full_nm_suffix	= nm_suffix;
-  const char *const full_gnm_suffix	= gnm_suffix;
+  const char *const full_nm_suffix	  = nm_suffix;
+  const char *const full_gnm_suffix	  = gnm_suffix;
 #ifdef LDD_SUFFIX
-  const char *const full_ldd_suffix	= ldd_suffix;
+  const char *const full_ldd_suffix	  = ldd_suffix;
 #endif
-  const char *const full_strip_suffix	= strip_suffix;
-  const char *const full_gstrip_suffix	= gstrip_suffix;
+  const char *const full_strip_suffix	  = strip_suffix;
+  const char *const full_gstrip_suffix	  = gstrip_suffix;
 #endif /* CROSS_DIRECTORY_STRUCTURE */
 
   const char *arg;
@@ -1132,7 +1140,13 @@
   const char **c_ptr;
   char **ld1_argv;
   const char **ld1;
-  bool use_plugin = false;
+  enum linker_select
+  {
+    DFLT_LINKER,
+    PLUGIN_LINKER,
+    GOLD_LINKER,
+    BFD_LINKER
+  } selected_linker = DFLT_LINKER;
 
   /* The kinds of symbols we will have to consider when scanning the
      outcome of a first pass link.  This is ALL to start with, then might
@@ -1209,15 +1223,21 @@
         else if (! strcmp (argv[i], "-flto-partition=none"))
 	  no_partition = true;
         else if ((! strncmp (argv[i], "-flto=", 6)
-		  || ! strcmp (argv[i], "-flto")) && ! use_plugin)
+		  || ! strcmp (argv[i], "-flto"))
+		 && selected_linker != PLUGIN_LINKER)
 	  lto_mode = LTO_MODE_WHOPR;
 	else if (!strncmp (argv[i], "-fno-lto", 8))
 	  lto_mode = LTO_MODE_NONE;
         else if (! strcmp (argv[i], "-plugin"))
 	  {
-	    use_plugin = true;
+	    selected_linker =  PLUGIN_LINKER;
 	    lto_mode = LTO_MODE_NONE;
 	  }
+	else if (! strcmp (argv[i], "-use-gold"))
+	  selected_linker = GOLD_LINKER;
+	else if (! strcmp (argv[i], "-use-ld"))
+	  selected_linker = BFD_LINKER;
+
 #ifdef COLLECT_EXPORT_LIST
 	/* since -brtl, -bexport, -b64 are not position dependent
 	   also check for them here */
@@ -1299,36 +1319,109 @@
   /* Try to discover a valid linker/nm/strip to use.  */
 
   /* Maybe we know the right file to use (if not cross).  */
-  ld_file_name = 0;
+  ld_file_name = NULL;
 #ifdef DEFAULT_LINKER
   if (access (DEFAULT_LINKER, X_OK) == 0)
     ld_file_name = DEFAULT_LINKER;
-  if (ld_file_name == 0)
+  if (ld_file_name == NULL)
 #endif
 #ifdef REAL_LD_FILE_NAME
   ld_file_name = find_a_file (&path, REAL_LD_FILE_NAME);
-  if (ld_file_name == 0)
+  if (ld_file_name == NULL)
 #endif
   /* Search the (target-specific) compiler dirs for ld'.  */
   ld_file_name = find_a_file (&cpath, real_ld_suffix);
   /* Likewise for `collect-ld'.  */
-  if (ld_file_name == 0)
+  if (ld_file_name == NULL)
     ld_file_name = find_a_file (&cpath, collect_ld_suffix);
   /* Search the compiler directories for `ld'.  We have protection against
      recursive calls in find_a_file.  */
-  if (ld_file_name == 0)
-    ld_file_name = find_a_file (&cpath,
-				use_plugin
-				? plugin_ld_suffix
-				: ld_suffix);
+  if (ld_file_name == NULL)
+    switch (selected_linker)
+      {
+      default:
+      case DFLT_LINKER:
+	ld_file_name = find_a_file (&cpath, ld_suffix);
+	break;
+      case PLUGIN_LINKER:
+	ld_file_name = find_a_file (&cpath, plugin_ld_suffix);
+	break;
+      case GOLD_LINKER:
+	ld_file_name = find_a_file (&cpath, gold_suffix);
+	break;
+      case BFD_LINKER:
+	ld_file_name = find_a_file (&cpath, bfd_ld_suffix);
+	break;
+      }
   /* Search the ordinary system bin directories
      for `ld' (if native linking) or `TARGET-ld' (if cross).  */
-  if (ld_file_name == 0)
-    ld_file_name = find_a_file (&path,
-				use_plugin
-				? full_plugin_ld_suffix
-				: full_ld_suffix);
+  if (ld_file_name == NULL)
+    switch (selected_linker)
+      {
+      default:
+      case DFLT_LINKER:
+	ld_file_name = find_a_file (&path, full_ld_suffix);
+	break;
+      case PLUGIN_LINKER:
+	ld_file_name = find_a_file (&path, full_plugin_ld_suffix);
+	break;
+      case GOLD_LINKER:
+	ld_file_name = find_a_file (&path, full_gold_suffix);
+	break;
+      case BFD_LINKER:
+	ld_file_name = find_a_file (&path, full_bfd_ld_suffix);
+	break;
+      }
+  /* If we failed to find a plugin-capable linker, try the ordinary one.  */
+  if (ld_file_name == NULL && selected_linker == PLUGIN_LINKER)
+    ld_file_name = find_a_file (&cpath, ld_suffix);
 
+  if ((vflag || debug) && ld_file_name == NULL)
+    {
+      struct prefix_list * p;
+      const char * s;
+
+      notice ("collect2: warning: unable to find linker.\n");
+
+#ifdef DEFAULT_LINKER
+      notice (" Searched for this absolute executable:\n");
+      notice (" %s\n", DEFAULT_LINKER);
+#endif
+
+      notice (" Searched in these paths:\n");
+      for (p = cpath.plist; p != NULL; p = p->next)
+	notice ("  %s\n", p->prefix);
+      notice (" For these executables:\n");
+      notice ("  %s\n", real_ld_suffix);
+      notice ("  %s\n", collect_ld_suffix);
+      switch (selected_linker)
+      {
+      default:
+      case DFLT_LINKER:    s = ld_suffix; break;
+      case PLUGIN_LINKER:  s = plugin_ld_suffix; break;
+      case GOLD_LINKER:    s = gold_suffix; break;
+      case BFD_LINKER:     s = bfd_ld_suffix; break;
+      }
+      notice ("  %s\n", s);
+
+      notice (" And searched in these paths:\n");
+      for (p = path.plist; p != NULL; p = p->next)
+	notice ("  %s\n", p->prefix);
+      notice (" For these executables:\n");
+#ifdef REAL_LD_FILE_NAME
+      notice (" %s\n", REAL_LD_FILE_NAME);
+#endif
+      switch (selected_linker)
+      {
+      default:
+      case DFLT_LINKER:    s = full_ld_suffix; break;
+      case PLUGIN_LINKER:  s = full_plugin_ld_suffix; break;
+      case GOLD_LINKER:    s = full_gold_suffix; break;
+      case BFD_LINKER:     s = full_bfd_ld_suffix; break;
+      }
+      notice ("  %s\n", s);
+    }
+
 #ifdef REAL_NM_FILE_NAME
   nm_file_name = find_a_file (&path, REAL_NM_FILE_NAME);
   if (nm_file_name == 0)

--
This patch is available for review at http://codereview.appspot.com/4664051