PR ld/12942

bfd/
	* elflink.c (elf_link_add_object_symbols): Use elf_discarded_section
	rather than kept_section to determine whether a symbol is from
	a discarded section.
	* cofflink.c (coff_link_add_symbols): Make symbols from discarded
	sections appear undefined.

	* elf-bfd.h (_bfd_elf_section_already_linked): Replace
	"asection *" with "struct already_linked *".
	* libbfd-in.h (_bfd_nolink_section_already_linked): Likewise.
	(_bfd_generic_section_already_linked): Likewise.
	(bfd_section_already_linked_table_insert): Likewise.
	(struct already_linked): New.
	(struct bfd_section_already_linked): Use it.
	* elflink.c (_bfd_elf_section_already_linked): Replace.
	"asection *" with "struct already_linked *".  Replace the plugin
	dummy with the LTO output.
	* linker.c (_bfd_generic_section_already_linked): Likewise.
	* targets.c (struct already_linked): Add forward declaration.
	(bfd_target): Replace "struct bfd_section *" with
	"struct already_linked *" in _section_already_linked.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.

include/
	* bfdlink.h (bfd_link_info): Add loading_lto_outputs.

ld/
	* ldlang.c (section_already_linked): Pass "struct already_linked *"
	to bfd_section_already_linked.
	(lang_process): Set link_info.loading_lto_outputs before
	loading LTO outputs.
	* plugin.c: Include "libbfd.h".
	(add_symbols): Call bfd_section_already_linked with comdat_key.

9 files changed, 371 insertions, 173 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 9a3dafb..a1b9197 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,32 @@
+2011-07-09  Alan Modra  <amodra@gmail.com>
+
+	PR ld/12942
+	* elflink.c (elf_link_add_object_symbols): Use elf_discarded_section
+	rather than kept_section to determine whether a symbol is from
+	a discarded section.
+	* cofflink.c (coff_link_add_symbols): Make symbols from discarded
+	sections appear undefined.
+
+2011-07-09  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/12942
+	* elf-bfd.h (_bfd_elf_section_already_linked): Replace
+	"asection *" with "struct already_linked *".
+	* libbfd-in.h (_bfd_nolink_section_already_linked): Likewise.
+	(_bfd_generic_section_already_linked): Likewise.
+	(bfd_section_already_linked_table_insert): Likewise.
+	(struct already_linked): New.
+	(struct bfd_section_already_linked): Use it.
+	* elflink.c (_bfd_elf_section_already_linked): Replace.
+	"asection *" with "struct already_linked *".  Replace the plugin
+	dummy with the LTO output.
+	* linker.c (_bfd_generic_section_already_linked): Likewise.
+	* targets.c (struct already_linked): Add forward declaration.
+	(bfd_target): Replace "struct bfd_section *" with
+	"struct already_linked *" in _section_already_linked.
+	* bfd-in2.h: Regenerate.
+	* libbfd.h: Regenerate.
+
 2011-07-06  Tristan Gingold  <gingold@adacore.com>
 
 	* mach-o.h: Move loader related definitions to
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 672c293..da4688c 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -5726,6 +5726,7 @@ enum bfd_endian { BFD_ENDIAN_BIG, BFD_ENDIAN_LITTLE, BFD_ENDIAN_UNKNOWN };
 
 /* Forward declaration.  */
 typedef struct bfd_link_info _bfd_link_info;
+struct already_linked;
 
 typedef struct bfd_target
 {
@@ -6051,7 +6052,7 @@ typedef struct bfd_target
 
   /* Check if SEC has been already linked during a reloceatable or
      final link.  */
-  void (*_section_already_linked) (bfd *, struct bfd_section *,
+  void (*_section_already_linked) (bfd *, struct already_linked *,
                                    struct bfd_link_info *);
 
   /* Define a common symbol.  */
@@ -6121,11 +6122,12 @@ bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec);
 #define bfd_link_split_section(abfd, sec) \
        BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec))
 
-void bfd_section_already_linked (bfd *abfd, asection *sec,
+void bfd_section_already_linked (bfd *abfd,
+    struct already_linked *data,
     struct bfd_link_info *info);
 
-#define bfd_section_already_linked(abfd, sec, info) \
-       BFD_SEND (abfd, _section_already_linked, (abfd, sec, info))
+#define bfd_section_already_linked(abfd, data, info) \
+       BFD_SEND (abfd, _section_already_linked, (abfd, data, info))
 
 bfd_boolean bfd_generic_define_common_symbol
    (bfd *output_bfd, struct bfd_link_info *info,
diff --git a/bfd/cofflink.c b/bfd/cofflink.c
index bca1364..27257ba 100644
--- a/bfd/cofflink.c
+++ b/bfd/cofflink.c
@@ -392,7 +392,11 @@ coff_link_add_symbols (bfd *abfd,
 	      section = coff_section_from_bfd_index (abfd, sym.n_scnum);
 	      if (! obj_pe (abfd))
 		value -= section->vma;
-	      break;
+	      /* Treat a symbol from a discarded section as undefined.  */
+	      if (bfd_is_abs_section (section)
+		  || !bfd_is_abs_section (section->output_section))
+		break;
+	      /* Fall thru */
 
 	    case COFF_SYMBOL_UNDEFINED:
 	      flags = 0;
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 64a9dc0..b2075a5 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1793,7 +1793,7 @@ extern bfd_boolean _bfd_elf_match_sections_by_type
 extern bfd_boolean bfd_elf_is_group_section
   (bfd *, const struct bfd_section *);
 extern void _bfd_elf_section_already_linked
-  (bfd *, struct bfd_section *, struct bfd_link_info *);
+  (bfd *, struct already_linked *, struct bfd_link_info *);
 extern void bfd_elf_set_group_contents
   (bfd *, asection *, void *);
 extern asection *_bfd_elf_check_kept_section
diff --git a/bfd/elflink.c b/bfd/elflink.c
index b518da8..238a4aa 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -3900,7 +3900,7 @@ error_free_dyn:
 	  sec = bfd_section_from_elf_index (abfd, isym->st_shndx);
 	  if (sec == NULL)
 	    sec = bfd_abs_section_ptr;
-	  else if (sec->kept_section)
+	  else if (elf_discarded_section (sec))
 	    {
 	      /* Symbols from discarded section are undefined.  We keep
 		 its visibility.  */
@@ -12438,63 +12438,100 @@ section_signature (asection *sec)
 }
 
 void
-_bfd_elf_section_already_linked (bfd *abfd, asection *sec,
+_bfd_elf_section_already_linked (bfd *abfd,
+				 struct already_linked *linked,
 				 struct bfd_link_info *info)
 {
   flagword flags;
   const char *name, *p;
   struct bfd_section_already_linked *l;
   struct bfd_section_already_linked_hash_entry *already_linked_list;
+  asection *sec, *l_sec;
 
-  if (sec->output_section == bfd_abs_section_ptr)
-    return;
-
-  flags = sec->flags;
-
-  /* Return if it isn't a linkonce section.  A comdat group section
-     also has SEC_LINK_ONCE set.  */
-  if ((flags & SEC_LINK_ONCE) == 0)
-    return;
-
-  /* Don't put group member sections on our list of already linked
-     sections.  They are handled as a group via their group section.  */
-  if (elf_sec_group (sec) != NULL)
-    return;
-
-  /* FIXME: When doing a relocatable link, we may have trouble
-     copying relocations in other sections that refer to local symbols
-     in the section being discarded.  Those relocations will have to
-     be converted somehow; as of this writing I'm not sure that any of
-     the backends handle that correctly.
-
-     It is tempting to instead not discard link once sections when
-     doing a relocatable link (technically, they should be discarded
-     whenever we are building constructors).  However, that fails,
-     because the linker winds up combining all the link once sections
-     into a single large link once section, which defeats the purpose
-     of having link once sections in the first place.
-
-     Also, not merging link once sections in a relocatable link
-     causes trouble for MIPS ELF, which relies on link once semantics
-     to handle the .reginfo section correctly.  */
-
-  name = section_signature (sec);
-
-  if (CONST_STRNEQ (name, ".gnu.linkonce.")
-      && (p = strchr (name + sizeof (".gnu.linkonce.") - 1, '.')) != NULL)
-    p++;
+  p = name = linked->comdat_key;
+  if (name)
+    {
+      sec = NULL;
+      flags = SEC_GROUP | SEC_LINK_ONCE | SEC_LINK_DUPLICATES_DISCARD;
+    }
   else
-    p = name;
+    {
+      sec = linked->u.sec;
+      if (sec->output_section == bfd_abs_section_ptr)
+	return;
+
+      flags = sec->flags;
+
+      /* Return if it isn't a linkonce section.  A comdat group section
+	 also has SEC_LINK_ONCE set.  */
+      if ((flags & SEC_LINK_ONCE) == 0)
+	return;
+
+      /* Don't put group member sections on our list of already linked
+	 sections.  They are handled as a group via their group section.
+	 */
+      if (elf_sec_group (sec) != NULL)
+	return;
+
+      /* FIXME: When doing a relocatable link, we may have trouble
+	 copying relocations in other sections that refer to local symbols
+	 in the section being discarded.  Those relocations will have to
+	 be converted somehow; as of this writing I'm not sure that any of
+	 the backends handle that correctly.
+
+	 It is tempting to instead not discard link once sections when
+	 doing a relocatable link (technically, they should be discarded
+	 whenever we are building constructors).  However, that fails,
+	 because the linker winds up combining all the link once sections
+	 into a single large link once section, which defeats the purpose
+	 of having link once sections in the first place.
+
+	 Also, not merging link once sections in a relocatable link
+	 causes trouble for MIPS ELF, which relies on link once semantics
+	 to handle the .reginfo section correctly.  */
+
+      name = section_signature (sec);
+
+      if (CONST_STRNEQ (name, ".gnu.linkonce.")
+	  && ((p = strchr (name + sizeof (".gnu.linkonce.") - 1, '.'))
+	      != NULL))
+	p++;
+      else
+	p = name;
+    }
 
   already_linked_list = bfd_section_already_linked_table_lookup (p);
 
   for (l = already_linked_list->entry; l != NULL; l = l->next)
     {
+      bfd_boolean l_coff_comdat_sec;
+      flagword l_flags;
+      bfd *l_owner;
+      const char *l_name = l->linked.comdat_key;
+      if (l_name)
+	{
+	  l_sec = NULL;
+	  l_owner = l->linked.u.abfd;
+	  l_flags = (SEC_GROUP
+		     | SEC_LINK_ONCE
+		     | SEC_LINK_DUPLICATES_DISCARD);
+	  l_coff_comdat_sec = FALSE;
+	}
+      else
+	{
+	  l_sec = l->linked.u.sec;
+	  l_owner = l_sec->owner;
+	  l_flags = l_sec->flags;
+	  l_coff_comdat_sec
+	    = !!bfd_coff_get_comdat_section (l_sec->owner, l_sec);
+	  l_name = section_signature (l_sec);
+	}
+
       /* We may have 2 different types of sections on the list: group
 	 sections and linkonce sections.  Match like sections.  */
-      if ((flags & SEC_GROUP) == (l->sec->flags & SEC_GROUP)
-	  && strcmp (name, section_signature (l->sec)) == 0
-	  && bfd_coff_get_comdat_section (l->sec->owner, l->sec) == NULL)
+      if ((flags & SEC_GROUP) == (l_flags & SEC_GROUP)
+	  && strcmp (name, l_name) == 0
+	  && !l_coff_comdat_sec)
 	{
 	  /* The section has already been linked.  See if we should
 	     issue a warning.  */
@@ -12504,6 +12541,18 @@ _bfd_elf_section_already_linked (bfd *abfd, asection *sec,
 	      abort ();
 
 	    case SEC_LINK_DUPLICATES_DISCARD:
+	      /* If we found an LTO IR match for this comdat group on
+		 the first pass, replace it with the LTO output on the
+		 second pass.  We can't simply choose real object
+		 files over IR because the first pass may contain a
+		 mix of LTO and normal objects and we must keep the
+		 first match, be it IR or real.  */
+	      if (info->loading_lto_outputs
+		  && (l_owner->flags & BFD_PLUGIN) != 0)
+		{
+		  l->linked = *linked;
+		  return;
+		}
 	      break;
 
 	    case SEC_LINK_DUPLICATES_ONE_ONLY:
@@ -12513,14 +12562,20 @@ _bfd_elf_section_already_linked (bfd *abfd, asection *sec,
 	      break;
 
 	    case SEC_LINK_DUPLICATES_SAME_SIZE:
-	      if (sec->size != l->sec->size)
+	      if (!sec || !l_sec)
+		abort ();
+
+	      if (sec->size != l_sec->size)
 		(*_bfd_error_handler)
 		  (_("%B: duplicate section `%A' has different size"),
 		   abfd, sec);
 	      break;
 
 	    case SEC_LINK_DUPLICATES_SAME_CONTENTS:
-	      if (sec->size != l->sec->size)
+	      if (!sec || !l_sec)
+		abort ();
+
+	      if (sec->size != l_sec->size)
 		(*_bfd_error_handler)
 		  (_("%B: duplicate section `%A' has different size"),
 		   abfd, sec);
@@ -12532,11 +12587,11 @@ _bfd_elf_section_already_linked (bfd *abfd, asection *sec,
 		    (*_bfd_error_handler)
 		      (_("%B: warning: could not read contents of section `%A'"),
 		       abfd, sec);
-		  else if (!bfd_malloc_and_get_section (l->sec->owner, l->sec,
+		  else if (!bfd_malloc_and_get_section (l_sec->owner, l_sec,
 							&l_sec_contents))
 		    (*_bfd_error_handler)
 		      (_("%B: warning: could not read contents of section `%A'"),
-		       l->sec->owner, l->sec);
+		       l_sec->owner, l_sec);
 		  else if (memcmp (sec_contents, l_sec_contents, sec->size) != 0)
 		    (*_bfd_error_handler)
 		      (_("%B: warning: duplicate section `%A' has different contents"),
@@ -12550,28 +12605,31 @@ _bfd_elf_section_already_linked (bfd *abfd, asection *sec,
 	      break;
 	    }
 
-	  /* Set the output_section field so that lang_add_section
-	     does not create a lang_input_section structure for this
-	     section.  Since there might be a symbol in the section
-	     being discarded, we must retain a pointer to the section
-	     which we are really going to use.  */
-	  sec->output_section = bfd_abs_section_ptr;
-	  sec->kept_section = l->sec;
-
-	  if (flags & SEC_GROUP)
+	  if (sec)
 	    {
-	      asection *first = elf_next_in_group (sec);
-	      asection *s = first;
+	      /* Set the output_section field so that lang_add_section
+		 does not create a lang_input_section structure for this
+		 section.  Since there might be a symbol in the section
+		 being discarded, we must retain a pointer to the section
+		 which we are really going to use.  */
+	      sec->output_section = bfd_abs_section_ptr;
+	      sec->kept_section = l_sec;
 
-	      while (s != NULL)
+	      if (flags & SEC_GROUP)
 		{
-		  s->output_section = bfd_abs_section_ptr;
-		  /* Record which group discards it.  */
-		  s->kept_section = l->sec;
-		  s = elf_next_in_group (s);
-		  /* These lists are circular.  */
-		  if (s == first)
-		    break;
+		  asection *first = elf_next_in_group (sec);
+		  asection *s = first;
+
+		  while (s != NULL)
+		    {
+		      s->output_section = bfd_abs_section_ptr;
+		      /* Record which group discards it.  */
+		      s->kept_section = l_sec;
+		      s = elf_next_in_group (s);
+		      /* These lists are circular.  */
+		      if (s == first)
+			break;
+		    }
 		}
 	    }
 
@@ -12579,67 +12637,100 @@ _bfd_elf_section_already_linked (bfd *abfd, asection *sec,
 	}
     }
 
-  /* A single member comdat group section may be discarded by a
-     linkonce section and vice versa.  */
-
-  if ((flags & SEC_GROUP) != 0)
+  if (sec)
     {
-      asection *first = elf_next_in_group (sec);
+      /* A single member comdat group section may be discarded by a
+	 linkonce section and vice versa.  */
 
-      if (first != NULL && elf_next_in_group (first) == first)
-	/* Check this single member group against linkonce sections.  */
-	for (l = already_linked_list->entry; l != NULL; l = l->next)
-	  if ((l->sec->flags & SEC_GROUP) == 0
-	      && bfd_coff_get_comdat_section (l->sec->owner, l->sec) == NULL
-	      && bfd_elf_match_symbols_in_sections (l->sec, first, info))
-	    {
-	      first->output_section = bfd_abs_section_ptr;
-	      first->kept_section = l->sec;
-	      sec->output_section = bfd_abs_section_ptr;
-	      break;
-	    }
-    }
-  else
-    /* Check this linkonce section against single member groups.  */
-    for (l = already_linked_list->entry; l != NULL; l = l->next)
-      if (l->sec->flags & SEC_GROUP)
+      if ((flags & SEC_GROUP) != 0)
 	{
-	  asection *first = elf_next_in_group (l->sec);
+	  asection *first = elf_next_in_group (sec);
 
-	  if (first != NULL
-	      && elf_next_in_group (first) == first
-	      && bfd_elf_match_symbols_in_sections (first, sec, info))
-	    {
-	      sec->output_section = bfd_abs_section_ptr;
-	      sec->kept_section = first;
-	      break;
-	    }
+	  if (first != NULL && elf_next_in_group (first) == first)
+	    /* Check this single member group against linkonce sections.  */
+	    for (l = already_linked_list->entry; l != NULL; l = l->next)
+	      {
+		if (l->linked.comdat_key == NULL)
+		  {
+		    l_sec = l->linked.u.sec;
+
+		    if ((l_sec->flags & SEC_GROUP) == 0
+			&& bfd_coff_get_comdat_section (l_sec->owner,
+							l_sec) == NULL
+			&& bfd_elf_match_symbols_in_sections (l_sec,
+							      first,
+							      info))
+		      {
+			first->output_section = bfd_abs_section_ptr;
+			first->kept_section = l_sec;
+			sec->output_section = bfd_abs_section_ptr;
+			break;
+		      }
+		  }
+	      }
 	}
+      else
+	/* Check this linkonce section against single member groups.  */
+	for (l = already_linked_list->entry; l != NULL; l = l->next)
+	  {
+	    if (l->linked.comdat_key == NULL)
+	      {
+		l_sec = l->linked.u.sec;
 
-  /* Do not complain on unresolved relocations in `.gnu.linkonce.r.F'
-     referencing its discarded `.gnu.linkonce.t.F' counterpart - g++-3.4
-     specific as g++-4.x is using COMDAT groups (without the `.gnu.linkonce'
-     prefix) instead.  `.gnu.linkonce.r.*' were the `.rodata' part of its
-     matching `.gnu.linkonce.t.*'.  If `.gnu.linkonce.r.F' is not discarded
-     but its `.gnu.linkonce.t.F' is discarded means we chose one-only
-     `.gnu.linkonce.t.F' section from a different bfd not requiring any
-     `.gnu.linkonce.r.F'.  Thus `.gnu.linkonce.r.F' should be discarded.
-     The reverse order cannot happen as there is never a bfd with only the
-     `.gnu.linkonce.r.F' section.  The order of sections in a bfd does not
-     matter as here were are looking only for cross-bfd sections.  */
-
-  if ((flags & SEC_GROUP) == 0 && CONST_STRNEQ (name, ".gnu.linkonce.r."))
-    for (l = already_linked_list->entry; l != NULL; l = l->next)
-      if ((l->sec->flags & SEC_GROUP) == 0
-	  && CONST_STRNEQ (l->sec->name, ".gnu.linkonce.t."))
-	{
-	  if (abfd != l->sec->owner)
-	    sec->output_section = bfd_abs_section_ptr;
-	  break;
-	}
+		if (l_sec->flags & SEC_GROUP)
+		  {
+		    asection *first = elf_next_in_group (l_sec);
+
+		    if (first != NULL
+			&& elf_next_in_group (first) == first
+			&& bfd_elf_match_symbols_in_sections (first,
+							      sec,
+							      info))
+		      {
+			sec->output_section = bfd_abs_section_ptr;
+			sec->kept_section = first;
+			break;
+		      }
+		  }
+	      }
+	  }
+
+      /* Do not complain on unresolved relocations in `.gnu.linkonce.r.F'
+	 referencing its discarded `.gnu.linkonce.t.F' counterpart -
+	 g++-3.4 specific as g++-4.x is using COMDAT groups (without the
+	 `.gnu.linkonce' prefix) instead.  `.gnu.linkonce.r.*' were the
+	 `.rodata' part of its matching `.gnu.linkonce.t.*'.  If
+	 `.gnu.linkonce.r.F' is not discarded but its `.gnu.linkonce.t.F'
+	 is discarded means we chose one-only `.gnu.linkonce.t.F' section
+	 from a different bfd not requiring any `.gnu.linkonce.r.F'.
+	 Thus `.gnu.linkonce.r.F' should be discarded.  The reverse order
+	 cannot happen as there is never a bfd with only the
+	 `.gnu.linkonce.r.F' section.  The order of sections in a bfd
+	 does not matter as here were are looking only for cross-bfd
+	 sections.  */
+
+      if ((flags & SEC_GROUP) == 0
+	  && CONST_STRNEQ (name, ".gnu.linkonce.r."))
+	for (l = already_linked_list->entry; l != NULL; l = l->next)
+	  {
+	    if (l->linked.comdat_key == NULL)
+	      {
+		l_sec = l->linked.u.sec;
+
+		if ((l_sec->flags & SEC_GROUP) == 0
+		    && CONST_STRNEQ (l_sec->name, ".gnu.linkonce.t."))
+		  {
+		    if (abfd != l_sec->owner)
+		      sec->output_section = bfd_abs_section_ptr;
+		    break;
+		  }
+	      }
+	  }
+    }
 
   /* This is the first section with this name.  Record it.  */
-  if (! bfd_section_already_linked_table_insert (already_linked_list, sec))
+  if (! bfd_section_already_linked_table_insert (already_linked_list,
+						 linked))
     info->callbacks->einfo (_("%F%P: already_linked_table: %E\n"));
 }
 
diff --git a/bfd/libbfd-in.h b/bfd/libbfd-in.h
index ad45ba3..a80687e 100644
--- a/bfd/libbfd-in.h
+++ b/bfd/libbfd-in.h
@@ -478,7 +478,8 @@ extern bfd_boolean _bfd_generic_set_section_contents
 #define _bfd_nolink_bfd_link_split_section \
   ((bfd_boolean (*) (bfd *, struct bfd_section *)) bfd_false)
 #define _bfd_nolink_section_already_linked \
-  ((void (*) (bfd *, struct bfd_section *, struct bfd_link_info *)) bfd_void)
+  ((void (*) (bfd *, struct already_linked*, \
+	      struct bfd_link_info *)) bfd_void)
 #define _bfd_nolink_bfd_define_common_symbol \
   ((bfd_boolean (*) (bfd *, struct bfd_link_info *, \
 		     struct bfd_link_hash_entry *)) bfd_false)
@@ -599,7 +600,7 @@ extern bfd_boolean _bfd_generic_link_split_section
   (bfd *, struct bfd_section *);
 
 extern void _bfd_generic_section_already_linked
-  (bfd *, struct bfd_section *, struct bfd_link_info *);
+  (bfd *, struct already_linked *, struct bfd_link_info *);
 
 /* Generic reloc_link_order processing routine.  */
 extern bfd_boolean _bfd_generic_reloc_link_order
@@ -791,16 +792,26 @@ struct bfd_section_already_linked_hash_entry
   struct bfd_section_already_linked *entry;
 };
 
+struct already_linked
+{
+  const char *comdat_key;
+  union
+    {
+      asection *sec;
+      bfd *abfd;
+    } u;
+};
+
 struct bfd_section_already_linked
 {
   struct bfd_section_already_linked *next;
-  asection *sec;
+  struct already_linked linked;
 };
 
 extern struct bfd_section_already_linked_hash_entry *
   bfd_section_already_linked_table_lookup (const char *);
 extern bfd_boolean bfd_section_already_linked_table_insert
-  (struct bfd_section_already_linked_hash_entry *, asection *);
+  (struct bfd_section_already_linked_hash_entry *, struct already_linked *);
 extern void bfd_section_already_linked_table_traverse
   (bfd_boolean (*) (struct bfd_section_already_linked_hash_entry *,
 		    void *), void *);
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index dd4cc94..c72ff16 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -483,7 +483,8 @@ extern bfd_boolean _bfd_generic_set_section_contents
 #define _bfd_nolink_bfd_link_split_section \
   ((bfd_boolean (*) (bfd *, struct bfd_section *)) bfd_false)
 #define _bfd_nolink_section_already_linked \
-  ((void (*) (bfd *, struct bfd_section *, struct bfd_link_info *)) bfd_void)
+  ((void (*) (bfd *, struct already_linked*, \
+		struct bfd_link_info *)) bfd_void)
 #define _bfd_nolink_bfd_define_common_symbol \
   ((bfd_boolean (*) (bfd *, struct bfd_link_info *, \
 		     struct bfd_link_hash_entry *)) bfd_false)
@@ -604,7 +605,7 @@ extern bfd_boolean _bfd_generic_link_split_section
   (bfd *, struct bfd_section *);
 
 extern void _bfd_generic_section_already_linked
-  (bfd *, struct bfd_section *, struct bfd_link_info *);
+  (bfd *, struct already_linked *, struct bfd_link_info *);
 
 /* Generic reloc_link_order processing routine.  */
 extern bfd_boolean _bfd_generic_reloc_link_order
@@ -796,16 +797,26 @@ struct bfd_section_already_linked_hash_entry
   struct bfd_section_already_linked *entry;
 };
 
+struct already_linked
+{
+  const char *comdat_key;
+  union
+    {
+      asection *sec;
+      bfd *abfd;
+    } u;
+};
+
 struct bfd_section_already_linked
 {
   struct bfd_section_already_linked *next;
-  asection *sec;
+  struct already_linked linked;
 };
 
 extern struct bfd_section_already_linked_hash_entry *
   bfd_section_already_linked_table_lookup (const char *);
 extern bfd_boolean bfd_section_already_linked_table_insert
-  (struct bfd_section_already_linked_hash_entry *, asection *);
+  (struct bfd_section_already_linked_hash_entry *, struct already_linked *);
 extern void bfd_section_already_linked_table_traverse
   (bfd_boolean (*) (struct bfd_section_already_linked_hash_entry *,
 		    void *), void *);
diff --git a/bfd/linker.c b/bfd/linker.c
index e472317..492e774 100644
--- a/bfd/linker.c
+++ b/bfd/linker.c
@@ -2888,15 +2888,16 @@ FUNCTION
 	bfd_section_already_linked
 
 SYNOPSIS
-        void bfd_section_already_linked (bfd *abfd, asection *sec,
+        void bfd_section_already_linked (bfd *abfd,
+					 struct already_linked *data,
 					 struct bfd_link_info *info);
 
 DESCRIPTION
-	Check if @var{sec} has been already linked during a reloceatable
+	Check if @var{data} has been already linked during a reloceatable
 	or final link.
 
-.#define bfd_section_already_linked(abfd, sec, info) \
-.       BFD_SEND (abfd, _section_already_linked, (abfd, sec, info))
+.#define bfd_section_already_linked(abfd, data, info) \
+.       BFD_SEND (abfd, _section_already_linked, (abfd, data, info))
 .
 
 */
@@ -2939,7 +2940,7 @@ bfd_section_already_linked_table_lookup (const char *name)
 bfd_boolean
 bfd_section_already_linked_table_insert
   (struct bfd_section_already_linked_hash_entry *already_linked_list,
-   asection *sec)
+   struct already_linked *data)
 {
   struct bfd_section_already_linked *l;
 
@@ -2949,7 +2950,7 @@ bfd_section_already_linked_table_insert
       bfd_hash_allocate (&_bfd_section_already_linked_table, sizeof *l);
   if (l == NULL)
     return FALSE;
-  l->sec = sec;
+  l->linked = *data;
   l->next = already_linked_list->entry;
   already_linked_list->entry = l;
   return TRUE;
@@ -2990,42 +2991,74 @@ bfd_section_already_linked_table_free (void)
 /* This is used on non-ELF inputs.  */
 
 void
-_bfd_generic_section_already_linked (bfd *abfd, asection *sec,
+_bfd_generic_section_already_linked (bfd *abfd,
+				     struct already_linked *linked,
 				     struct bfd_link_info *info)
 {
   flagword flags;
   const char *name;
   struct bfd_section_already_linked *l;
   struct bfd_section_already_linked_hash_entry *already_linked_list;
+  struct coff_comdat_info *s_comdat;
+  asection *sec;
 
-  flags = sec->flags;
-  if ((flags & SEC_LINK_ONCE) == 0)
-    return;
-
-  /* FIXME: When doing a relocatable link, we may have trouble
-     copying relocations in other sections that refer to local symbols
-     in the section being discarded.  Those relocations will have to
-     be converted somehow; as of this writing I'm not sure that any of
-     the backends handle that correctly.
-
-     It is tempting to instead not discard link once sections when
-     doing a relocatable link (technically, they should be discarded
-     whenever we are building constructors).  However, that fails,
-     because the linker winds up combining all the link once sections
-     into a single large link once section, which defeats the purpose
-     of having link once sections in the first place.  */
-
-  name = bfd_get_section_name (abfd, sec);
+  name = linked->comdat_key;
+  if (name)
+    {
+      sec = NULL;
+      flags = SEC_GROUP | SEC_LINK_ONCE | SEC_LINK_DUPLICATES_DISCARD;
+      s_comdat = NULL;
+    }
+  else
+    {
+      sec = linked->u.sec;
+      flags = sec->flags;
+      if ((flags & SEC_LINK_ONCE) == 0)
+	return;
+
+      s_comdat = bfd_coff_get_comdat_section (abfd, sec);
+
+      /* FIXME: When doing a relocatable link, we may have trouble
+	 copying relocations in other sections that refer to local symbols
+	 in the section being discarded.  Those relocations will have to
+	 be converted somehow; as of this writing I'm not sure that any of
+	 the backends handle that correctly.
+
+	 It is tempting to instead not discard link once sections when
+	 doing a relocatable link (technically, they should be discarded
+	 whenever we are building constructors).  However, that fails,
+	 because the linker winds up combining all the link once sections
+	 into a single large link once section, which defeats the purpose
+	 of having link once sections in the first place.  */
+
+      name = bfd_get_section_name (abfd, sec);
+    }
 
   already_linked_list = bfd_section_already_linked_table_lookup (name);
 
   for (l = already_linked_list->entry; l != NULL; l = l->next)
     {
       bfd_boolean skip = FALSE;
-      struct coff_comdat_info *s_comdat
-	= bfd_coff_get_comdat_section (abfd, sec);
-      struct coff_comdat_info *l_comdat
-	= bfd_coff_get_comdat_section (l->sec->owner, l->sec);
+      bfd *l_owner;
+      flagword l_flags;
+      struct coff_comdat_info *l_comdat;
+      asection *l_sec;
+
+      if (l->linked.comdat_key)
+	{
+	  l_sec = NULL;
+	  l_owner = l->linked.u.abfd;
+	  l_comdat = NULL;
+	  l_flags = (SEC_GROUP
+		     | SEC_LINK_ONCE
+		     | SEC_LINK_DUPLICATES_DISCARD);
+	}
+      else
+	{
+	  l_sec = l->linked.u.sec;
+	  l_owner = l_sec->owner;
+	  l_comdat = bfd_coff_get_comdat_section (l_sec->owner, l_sec);
+	}
 
       /* We may have 3 different sections on the list: group section,
 	 comdat section and linkonce section. SEC may be a linkonce or
@@ -3034,7 +3067,7 @@ _bfd_generic_section_already_linked (bfd *abfd, asection *sec,
 
 	 FIXME: Is that safe to match a linkonce section with a comdat
 	 section for COFF inputs?  */
-      if ((l->sec->flags & SEC_GROUP) != 0)
+      if ((l_flags & SEC_GROUP) != 0)
 	skip = TRUE;
       else if (bfd_get_flavour (abfd) == bfd_target_coff_flavour)
 	{
@@ -3056,6 +3089,18 @@ _bfd_generic_section_already_linked (bfd *abfd, asection *sec,
 	      abort ();
 
 	    case SEC_LINK_DUPLICATES_DISCARD:
+	      /* If we found an LTO IR match for this comdat group on
+		 the first pass, replace it with the LTO output on the
+		 second pass.  We can't simply choose real object
+		 files over IR because the first pass may contain a
+		 mix of LTO and normal objects and we must keep the
+		 first match, be it IR or real.  */
+	      if (info->loading_lto_outputs
+		  && (l_owner->flags & BFD_PLUGIN) != 0)
+		{
+		  l->linked = *linked;
+		  return;
+		}
 	      break;
 
 	    case SEC_LINK_DUPLICATES_ONE_ONLY:
@@ -3072,27 +3117,31 @@ _bfd_generic_section_already_linked (bfd *abfd, asection *sec,
                  either.  */
 	      /* Fall through.  */
 	    case SEC_LINK_DUPLICATES_SAME_SIZE:
-	      if (sec->size != l->sec->size)
+	      if (sec->size != l_sec->size)
 		(*_bfd_error_handler)
 		  (_("%B: warning: duplicate section `%A' has different size\n"),
 		   abfd, sec);
 	      break;
 	    }
 
-	  /* Set the output_section field so that lang_add_section
-	     does not create a lang_input_section structure for this
-	     section.  Since there might be a symbol in the section
-	     being discarded, we must retain a pointer to the section
-	     which we are really going to use.  */
-	  sec->output_section = bfd_abs_section_ptr;
-	  sec->kept_section = l->sec;
+	  if (sec)
+	    {
+	      /* Set the output_section field so that lang_add_section
+		 does not create a lang_input_section structure for this
+		 section.  Since there might be a symbol in the section
+		 being discarded, we must retain a pointer to the section
+		 which we are really going to use.  */
+	      sec->output_section = bfd_abs_section_ptr;
+	      sec->kept_section = l_sec;
+	    }
 
 	  return;
 	}
     }
 
   /* This is the first section with this name.  Record it.  */
-  if (! bfd_section_already_linked_table_insert (already_linked_list, sec))
+  if (! bfd_section_already_linked_table_insert (already_linked_list,
+						 linked))
     info->callbacks->einfo (_("%F%P: already_linked_table: %E\n"));
 }
 
diff --git a/bfd/targets.c b/bfd/targets.c
index 52dcd6b..ac978a1 100644
--- a/bfd/targets.c
+++ b/bfd/targets.c
@@ -176,6 +176,7 @@ DESCRIPTION
 .
 .{* Forward declaration.  *}
 .typedef struct bfd_link_info _bfd_link_info;
+.struct already_linked;
 .
 .typedef struct bfd_target
 .{
@@ -503,7 +504,7 @@ BFD_JUMP_TABLE macros.
 .
 .  {* Check if SEC has been already linked during a reloceatable or
 .     final link.  *}
-.  void (*_section_already_linked) (bfd *, struct bfd_section *,
+.  void (*_section_already_linked) (bfd *, struct already_linked *,
 .				    struct bfd_link_info *);
 .
 .  {* Define a common symbol.  *}