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.

1 files changed, 88 insertions, 39 deletions

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"));
 }