diff mbox

[7/7] Plug ipa-prop escape analysis into gimple_call_arg_flags

Message ID 20140524073913.GA27708@kam.mff.cuni.cz
State New
Headers show

Commit Message

Jan Hubicka May 24, 2014, 7:39 a.m. UTC
> I'm fine with enlarging tree_function_decl for now - ideally we'd push
> stuff from it elsewhere (like target and optimization option tree nodes,
> or most of the visibility and symbol related stuff).  Not sure why
> tree_type_decl inherits from tree_decl_non_common (and thus
> tree_decl_with_vis).  Probably because of the non-common parts
> being (ab-)used by FEs.  Otherwise I'd say simply put a symtab
> node pointer into tree_decl_with_vis ... (can we move
> section_name and comdat_group more easily than assembler_name?)

Hi,
this patch removes comdat_group pointer and adds direct symtab pointer.  As
expected, the change is not completely easy. The main uglyness in C++'s version
of duplicate_decl that creates a duplicated decl with duplicated symtab node
now and needs to remove it.  Other problem is copy_node and c's duplicate_decl
that does memcpy on a node and thus also copie the symtab pointer that is not
the right thing to do.

On the other hand on middle-end side several things simplify, so I think overall
the approach works relatively well.

I have bootstrapped/regtested x86_64-linux and I plan to give it more testing
tomorrow and commit if there are no complains.  Incrementally I would like then
to cleanup way the decl_with_vis.symtab_node pointer is maintained.  I do not
want to allow users to tamper with it, so I did not make accessor macro for
it, however there are more direct uses than I would like: I will need to figure
out how to reduce those.

I can also incrementally move DECL_SECTION and some other stuff I think now.

Honza

	* tree-core.h (tree_decl_with_vis): Replace comdat_group by
	symtab_node pointer.
	* tree.c (copy_node_stat): Be sure tonot copy
	symtab_node pointer.
	(find_decls_types_r): Do not walk COMDAT_GROUP.
	* tree.h (DECL_COMDAT_GROUP): Revamp to use decl_comdat_group.
	* varasm.c (make_decl_one_only): Use set_comdat_group;
	create node if needed.
	* ipa-inline-transform.c (save_inline_function_body): Update
	way we decl->symtab mapping.
	* symtab.c (symtab_hash, hash_node, eq_node
	symtab_insert_node_to_hashtable): Remove.
	(symtab_register_node): Update.
	(symtab_unregister_node): Update.
	(symtab_get_node): Reimplement as inline function.
	(symtab_add_to_same_comdat_group): Update.
	(symtab_dissolve_same_comdat_group_list): Update.
	(dump_symtab_base): Update.
	(verify_symtab_base): Update.
	(symtab_make_decl_local): Update.
	(fixup_same_cpp_alias_visibility): Update.
	(symtab_nonoverwritable_alias): Update.
	* cgraphclones.c (set_new_clone_decl_and_node_flags): Update.
	* ipa.c (update_visibility_by_resolution_info): UPdate.
	* bb-reorder.c: Include cgraph.h
	* lto-streamer-out.c (DFS_write_tree_body, hash_tree): Do not deal
	with comdat groups.
	* ipa-comdats.c (set_comdat_group, ipa_comdats): Update.
	* cgraph.c (cgraph_get_create_node): Update.
	* cgraph.h (struct symtab_node): Add get_comdat_group, set_comdat_group
	and comdat_group_.
	(symtab_get_node): Make inline.
	(symtab_insert_node_to_hashtable): Remove.
	(symtab_can_be_discarded): Update.
	(decl_comdat_group): New function.
	* tree-streamer-in.c (lto_input_ts_decl_with_vis_tree_pointers): Update.
	* lto-cgraph.c (lto_output_node, lto_output_varpool_node): Stream out
	comdat group name.
	(read_comdat_group): New function.
	(input_node, input_varpool_node): Use it.
	* trans-mem.c (ipa_tm_create_version_alias): Update code creating
	comdat groups.
	* mips.c (mips_start_unique_function): Likewise.
	(ix86_code_end): Likewise.
	(rs6000_code_end): Likweise.
	* tree-streamer-out.c (DECL_COMDAT_GROUP): Do not stream
	comdat group.

	* lto-symtab.c (lto_symtab_merge_symbols): Update code setting
	symtab pointer.
	* lto.c (compare_tree_sccs_1): Do not compare comdat groups.

	* optmize.c (maybe_thunk_body): Use set_comdat_group.
	(maybe_clone_body): Likewise.
	* decl.c (duplicate_decls): Update code duplicating comdat group;
	do not copy symtab pointer; before freeing newdecl remove it
	from symtab.
	* decl2.c (constrain_visibility): Use set_comdat_group.

	* c-decl.c (merge_decls): Preserve symtab node pointers.
	(duplicate_decls): Free new decl.
diff mbox

Patch

Index: tree-core.h
===================================================================
--- tree-core.h	(revision 210887)
+++ tree-core.h	(working copy)
@@ -1442,7 +1442,7 @@  struct GTY(()) tree_decl_with_vis {
  struct tree_decl_with_rtl common;
  tree assembler_name;
  tree section_name;
- tree comdat_group;
+ struct symtab_node *symtab_node;
 
  /* Belong to VAR_DECL exclusively.  */
  unsigned defer_output : 1;
Index: tree.c
===================================================================
--- tree.c	(revision 210887)
+++ tree.c	(working copy)
@@ -972,14 +972,20 @@  copy_node_stat (tree node MEM_STAT_DECL)
 	}
       /* DECL_DEBUG_EXPR is copied explicitely by callers.  */
       if (TREE_CODE (node) == VAR_DECL)
-	DECL_HAS_DEBUG_EXPR_P (t) = 0;
+	{
+	  DECL_HAS_DEBUG_EXPR_P (t) = 0;
+	  t->decl_with_vis.symtab_node = NULL;
+	}
       if (TREE_CODE (node) == VAR_DECL && DECL_HAS_INIT_PRIORITY_P (node))
 	{
 	  SET_DECL_INIT_PRIORITY (t, DECL_INIT_PRIORITY (node));
 	  DECL_HAS_INIT_PRIORITY_P (t) = 1;
 	}
       if (TREE_CODE (node) == FUNCTION_DECL)
-	DECL_STRUCT_FUNCTION (t) = NULL;
+	{
+	  DECL_STRUCT_FUNCTION (t) = NULL;
+	  t->decl_with_vis.symtab_node = NULL;
+	}
     }
   else if (TREE_CODE_CLASS (code) == tcc_type)
     {
@@ -5238,7 +5244,6 @@  find_decls_types_r (tree *tp, int *ws, v
       else if (TREE_CODE (t) == VAR_DECL)
 	{
 	  fld_worklist_push (DECL_SECTION_NAME (t), fld);
-	  fld_worklist_push (DECL_COMDAT_GROUP (t), fld);
 	}
 
       if ((TREE_CODE (t) == VAR_DECL || TREE_CODE (t) == PARM_DECL)
Index: tree.h
===================================================================
--- tree.h	(revision 210887)
+++ tree.h	(working copy)
@@ -2323,7 +2323,7 @@  extern void decl_value_expr_insert (tree
   (DECL_WITH_VIS_CHECK (NODE)->decl_with_vis.comdat_flag)
 
 #define DECL_COMDAT_GROUP(NODE) \
-  (DECL_WITH_VIS_CHECK (NODE)->decl_with_vis.comdat_group)
+  decl_comdat_group (NODE)
 
 /* Used in TREE_PUBLIC decls to indicate that copies of this DECL in
    multiple translation units should be merged.  */
Index: varasm.c
===================================================================
--- varasm.c	(revision 210887)
+++ varasm.c	(working copy)
@@ -5919,17 +5919,23 @@  supports_one_only (void)
 void
 make_decl_one_only (tree decl, tree comdat_group)
 {
+  struct symtab_node *symbol;
   gcc_assert (TREE_CODE (decl) == VAR_DECL
 	      || TREE_CODE (decl) == FUNCTION_DECL);
 
   TREE_PUBLIC (decl) = 1;
 
+  if (TREE_CODE (decl) == VAR_DECL)
+    symbol = varpool_node_for_decl (decl);
+  else
+    symbol = cgraph_get_create_node (decl);
+
   if (SUPPORTS_ONE_ONLY)
     {
 #ifdef MAKE_DECL_ONE_ONLY
       MAKE_DECL_ONE_ONLY (decl);
 #endif
-      DECL_COMDAT_GROUP (decl) = comdat_group;
+      symbol->set_comdat_group (comdat_group);
     }
   else if (TREE_CODE (decl) == VAR_DECL
       && (DECL_INITIAL (decl) == 0 || DECL_INITIAL (decl) == error_mark_node))
Index: ipa-inline-transform.c
===================================================================
--- ipa-inline-transform.c	(revision 210887)
+++ ipa-inline-transform.c	(working copy)
@@ -341,7 +341,7 @@  save_inline_function_body (struct cgraph
   /* first_clone will be turned into real function.  */
   first_clone = node->clones;
   first_clone->decl = copy_node (node->decl);
-  symtab_insert_node_to_hashtable (first_clone);
+  first_clone->decl->decl_with_vis.symtab_node = first_clone;
   gcc_assert (first_clone == cgraph_get_node (first_clone->decl));
 
   /* Now reshape the clone tree, so all other clones descends from
Index: cp/optimize.c
===================================================================
--- cp/optimize.c	(revision 210887)
+++ cp/optimize.c	(working copy)
@@ -285,7 +285,7 @@  maybe_thunk_body (tree fn, bool force)
   else if (HAVE_COMDAT_GROUP)
     {
       tree comdat_group = cdtor_comdat_group (fns[1], fns[0]);
-      DECL_COMDAT_GROUP (fns[0]) = comdat_group;
+      cgraph_get_create_node (fns[0])->set_comdat_group (comdat_group);
       symtab_add_to_same_comdat_group (cgraph_get_create_node (fns[1]),
 				       cgraph_get_create_node (fns[0]));
       symtab_add_to_same_comdat_group (symtab_get_node (fn),
@@ -473,7 +473,7 @@  maybe_clone_body (tree fn)
 	 name of fn was corrupted by write_mangled_name by adding *INTERNAL*
 	 to it. By doing so, it also corrupted the comdat group. */
       if (DECL_ONE_ONLY (fn))
-	DECL_COMDAT_GROUP (clone) = cxx_comdat_group (clone);
+	cgraph_get_create_node (clone)->set_comdat_group (cxx_comdat_group (clone));
       DECL_SECTION_NAME (clone) = DECL_SECTION_NAME (fn);
       DECL_USE_TEMPLATE (clone) = DECL_USE_TEMPLATE (fn);
       DECL_EXTERNAL (clone) = DECL_EXTERNAL (fn);
@@ -550,7 +550,7 @@  maybe_clone_body (tree fn)
 		 into the same, *[CD]5* comdat group instead of
 		 *[CD][12]*.  */
 	      comdat_group = cdtor_comdat_group (fns[1], fns[0]);
-	      DECL_COMDAT_GROUP (fns[0]) = comdat_group;
+	      cgraph_get_create_node (fns[0])->set_comdat_group (comdat_group);
 	      symtab_add_to_same_comdat_group (symtab_get_node (clone),
 					       symtab_get_node (fns[0]));
 	    }
Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 210887)
+++ cp/decl.c	(working copy)
@@ -2065,8 +2065,17 @@  duplicate_decls (tree newdecl, tree oldd
   /* Merge the storage class information.  */
   merge_weak (newdecl, olddecl);
 
-  if (DECL_ONE_ONLY (olddecl))
-    DECL_COMDAT_GROUP (newdecl) = DECL_COMDAT_GROUP (olddecl);
+  if ((TREE_CODE (olddecl) == FUNCTION_DECL || TREE_CODE (olddecl) == VAR_DECL)
+      && (DECL_EXTERNAL (olddecl) || TREE_PUBLIC (olddecl) || TREE_STATIC (olddecl))
+      && DECL_ONE_ONLY (olddecl))
+    {
+      struct symtab_node *symbol;
+      if (TREE_CODE (olddecl) == FUNCTION_DECL)
+	symbol = cgraph_get_create_node (newdecl);
+      else
+	symbol = varpool_node_for_decl (newdecl);
+      symbol->set_comdat_group (symtab_get_node (olddecl)->get_comdat_group ());
+    }
 
   DECL_DEFER_OUTPUT (newdecl) |= DECL_DEFER_OUTPUT (olddecl);
   TREE_PUBLIC (newdecl) = TREE_PUBLIC (olddecl);
@@ -2376,6 +2385,7 @@  duplicate_decls (tree newdecl, tree oldd
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
       int function_size;
+      struct symtab_node *snode = symtab_get_node (olddecl);
 
       function_size = sizeof (struct tree_decl_common);
 
@@ -2386,6 +2396,10 @@  duplicate_decls (tree newdecl, tree oldd
       memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
 	      (char *) newdecl + sizeof (struct tree_decl_common),
 	      sizeof (struct tree_function_decl) - sizeof (struct tree_decl_common));
+
+      /* Preserve symtab node mapping.  */
+      olddecl->decl_with_vis.symtab_node = snode;
+
       if (new_template_info)
 	/* If newdecl is a template instantiation, it is possible that
 	   the following sequence of events has occurred:
@@ -2415,6 +2429,7 @@  duplicate_decls (tree newdecl, tree oldd
   else
     {
       size_t size = tree_code_size (TREE_CODE (olddecl));
+
       memcpy ((char *) olddecl + sizeof (struct tree_common),
 	      (char *) newdecl + sizeof (struct tree_common),
 	      sizeof (struct tree_decl_common) - sizeof (struct tree_common));
@@ -2428,10 +2443,17 @@  duplicate_decls (tree newdecl, tree oldd
 	case TYPE_DECL:
 	case CONST_DECL:
 	  {
+            struct symtab_node *snode = NULL;
+
+            if (TREE_CODE (olddecl) == VAR_DECL
+		&& (TREE_STATIC (olddecl) || TREE_PUBLIC (olddecl) || DECL_EXTERNAL (olddecl)))
+	      snode = symtab_get_node (olddecl);
 	    memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
 		    (char *) newdecl + sizeof (struct tree_decl_common),
 		    size - sizeof (struct tree_decl_common)
 		    + TREE_CODE_LENGTH (TREE_CODE (newdecl)) * sizeof (char *));
+            if (TREE_CODE (olddecl) == VAR_DECL)
+	      olddecl->decl_with_vis.symtab_node = snode;
 	  }
 	  break;
 	default:
@@ -2466,7 +2488,21 @@  duplicate_decls (tree newdecl, tree oldd
 
   /* The NEWDECL will no longer be needed.  Because every out-of-class
      declaration of a member results in a call to duplicate_decls,
-     freeing these nodes represents in a significant savings.  */
+     freeing these nodes represents in a significant savings.
+
+     Before releasing the node, be sore to remove function from symbol
+     table that might have been inserted there to record comdat group.
+     Be sure to however do not free DECL_STRUCT_FUNCTION becuase this
+     structure is shared in between newdecl and oldecl.  */
+  if (TREE_CODE (newdecl) == FUNCTION_DECL)
+    DECL_STRUCT_FUNCTION (newdecl) = NULL;
+  if (TREE_CODE (newdecl) == FUNCTION_DECL
+      || TREE_CODE (newdecl) == VAR_DECL)
+    {
+      struct symtab_node *snode = symtab_get_node (newdecl);
+      if (snode)
+	symtab_remove_node (snode);
+    }
   ggc_free (newdecl);
 
   return olddecl;
Index: cp/decl2.c
===================================================================
--- cp/decl2.c	(revision 210887)
+++ cp/decl2.c	(working copy)
@@ -2093,7 +2093,14 @@  constrain_visibility (tree decl, int vis
 	  TREE_PUBLIC (decl) = 0;
 	  DECL_WEAK (decl) = 0;
 	  DECL_COMMON (decl) = 0;
-	  DECL_COMDAT_GROUP (decl) = NULL_TREE;
+	  if (TREE_CODE (decl) == FUNCTION_DECL
+	      || TREE_CODE (decl) == VAR_DECL)
+	    {
+	      struct symtab_node *snode = symtab_get_node (decl);
+
+	      if (snode)
+	        snode->set_comdat_group (NULL);
+	    }
 	  DECL_INTERFACE_KNOWN (decl) = 1;
 	  if (DECL_LANG_SPECIFIC (decl))
 	    DECL_NOT_REALLY_EXTERN (decl) = 1;
Index: symtab.c
===================================================================
--- symtab.c	(revision 210887)
+++ symtab.c	(working copy)
@@ -57,8 +57,6 @@  const char * const ld_plugin_symbol_reso
   "prevailing_def_ironly_exp"
 };
 
-/* Hash table used to convert declarations into nodes.  */
-static GTY((param_is (symtab_node))) htab_t symtab_hash;
 /* Hash table used to convert assembler names into nodes.  */
 static GTY((param_is (symtab_node))) htab_t assembler_name_hash;
 
@@ -70,26 +68,6 @@  symtab_node *symtab_nodes;
    them, to support -fno-toplevel-reorder.  */
 int symtab_order;
 
-/* Returns a hash code for P.  */
-
-static hashval_t
-hash_node (const void *p)
-{
-  const symtab_node *n = (const symtab_node *) p;
-  return (hashval_t) DECL_UID (n->decl);
-}
-
-
-/* Returns nonzero if P1 and P2 are equal.  */
-
-static int
-eq_node (const void *p1, const void *p2)
-{
-  const symtab_node *n1 = (const symtab_node *) p1;
-  const symtab_node *n2 = (const symtab_node *) p2;
-  return DECL_UID (n1->decl) == DECL_UID (n2->decl);
-}
-
 /* Hash asmnames ignoring the user specified marks.  */
 
 static hashval_t
@@ -282,21 +260,14 @@  symtab_prevail_in_asm_name_hash (symtab_
 void
 symtab_register_node (symtab_node *node)
 {
-  struct symtab_node key;
-  symtab_node **slot;
-
   node->next = symtab_nodes;
   node->previous = NULL;
   if (symtab_nodes)
     symtab_nodes->previous = node;
   symtab_nodes = node;
 
-  if (!symtab_hash)
-    symtab_hash = htab_create_ggc (10, hash_node, eq_node, NULL);
-  key.decl = node->decl;
-  slot = (symtab_node **) htab_find_slot (symtab_hash, &key, INSERT);
-  if (*slot == NULL)
-    *slot = node;
+  if (!node->decl->decl_with_vis.symtab_node)
+    node->decl->decl_with_vis.symtab_node = node;
 
   ipa_empty_ref_list (&node->ref_list);
 
@@ -307,22 +278,6 @@  symtab_register_node (symtab_node *node)
   insert_to_assembler_name_hash (node, false);
 }
 
-/* Make NODE to be the one symtab hash is pointing to.  Used when reshaping tree
-   of inline clones.  */
-
-void
-symtab_insert_node_to_hashtable (symtab_node *node)
-{
-  struct symtab_node key;
-  symtab_node **slot;
-
-  if (!symtab_hash)
-    symtab_hash = htab_create_ggc (10, hash_node, eq_node, NULL);
-  key.decl = node->decl;
-  slot = (symtab_node **) htab_find_slot (symtab_hash, &key, INSERT);
-  *slot = node;
-}
-
 /* Remove NODE from same comdat group.   */
 
 void
@@ -349,7 +304,6 @@  symtab_remove_from_same_comdat_group (sy
 void
 symtab_unregister_node (symtab_node *node)
 {
-  void **slot;
   ipa_remove_all_references (&node->ref_list);
   ipa_remove_all_referring (&node->ref_list);
 
@@ -364,55 +318,20 @@  symtab_unregister_node (symtab_node *nod
   node->next = NULL;
   node->previous = NULL;
 
-  slot = htab_find_slot (symtab_hash, node, NO_INSERT);
-
   /* During LTO symtab merging we temporarily corrupt decl to symtab node
      hash.  */
-  gcc_assert ((slot && *slot) || in_lto_p);
-  if (slot && *slot && *slot == node)
+  gcc_assert (node->decl->decl_with_vis.symtab_node || in_lto_p);
+  if (node->decl->decl_with_vis.symtab_node == node)
     {
       symtab_node *replacement_node = NULL;
       if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node))
 	replacement_node = cgraph_find_replacement_node (cnode);
-      if (!replacement_node)
-	htab_clear_slot (symtab_hash, slot);
-      else
-	*slot = replacement_node;
+      node->decl->decl_with_vis.symtab_node = replacement_node;
     }
   if (!is_a <varpool_node *> (node) || !DECL_HARD_REGISTER (node->decl))
     unlink_from_assembler_name_hash (node, false);
 }
 
-/* Return symbol table node associated with DECL, if any,
-   and NULL otherwise.  */
-
-symtab_node *
-symtab_get_node (const_tree decl)
-{
-  symtab_node **slot;
-  struct symtab_node key;
-
-#ifdef ENABLE_CHECKING
-  /* Check that we are called for sane type of object - functions
-     and static or external variables.  */
-  gcc_checking_assert (TREE_CODE (decl) == FUNCTION_DECL
-		       || (TREE_CODE (decl) == VAR_DECL
-			   && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)
-			       || in_lto_p)));
-#endif
-
-  if (!symtab_hash)
-    return NULL;
-
-  key.decl = CONST_CAST2 (tree, const_tree, decl);
-
-  slot = (symtab_node **) htab_find_slot (symtab_hash, &key,
-					 NO_INSERT);
-
-  if (slot)
-    return *slot;
-  return NULL;
-}
 
 /* Remove symtab NODE from the symbol table.  */
 
@@ -513,11 +432,11 @@  void
 symtab_add_to_same_comdat_group (symtab_node *new_node,
 				 symtab_node *old_node)
 {
-  gcc_assert (DECL_COMDAT_GROUP (old_node->decl));
+  gcc_assert (old_node->get_comdat_group ());
   gcc_assert (!new_node->same_comdat_group);
   gcc_assert (new_node != old_node);
 
-  DECL_COMDAT_GROUP (new_node->decl) = DECL_COMDAT_GROUP (old_node->decl);
+  new_node->set_comdat_group (old_node->get_comdat_group ());
   new_node->same_comdat_group = old_node;
   if (!old_node->same_comdat_group)
     old_node->same_comdat_group = new_node;
@@ -546,10 +465,10 @@  symtab_dissolve_same_comdat_group_list (
     {
       next = n->same_comdat_group;
       n->same_comdat_group = NULL;
-      /* Clear DECL_COMDAT_GROUP for comdat locals, since
+      /* Clear comdat_group for comdat locals, since
          make_decl_local doesn't.  */
       if (!TREE_PUBLIC (n->decl))
-	DECL_COMDAT_GROUP (n->decl) = NULL_TREE;
+	n->set_comdat_group (NULL);
       n = next;
     }
   while (n != node);
@@ -639,9 +558,9 @@  dump_symtab_base (FILE *f, symtab_node *
     fprintf (f, " dll_import");
   if (DECL_COMDAT (node->decl))
     fprintf (f, " comdat");
-  if (DECL_COMDAT_GROUP (node->decl))
+  if (node->get_comdat_group ())
     fprintf (f, " comdat_group:%s",
-	     IDENTIFIER_POINTER (DECL_COMDAT_GROUP (node->decl)));
+	     IDENTIFIER_POINTER (node->get_comdat_group ()));
   if (DECL_ONE_ONLY (node->decl))
     fprintf (f, " one_only");
   if (DECL_SECTION_NAME (node->decl))
@@ -766,7 +685,7 @@  verify_symtab_base (symtab_node *node)
       hashed_node = symtab_get_node (node->decl);
       if (!hashed_node)
 	{
-	  error ("node not found in symtab decl hashtable");
+	  error ("node not found node->decl->decl_with_vis.symtab_node");
 	  error_found = true;
 	}
       if (hashed_node != node
@@ -775,7 +694,7 @@  verify_symtab_base (symtab_node *node)
 	      || dyn_cast <cgraph_node *> (node)->clone_of->decl
 		 != node->decl))
 	{
-	  error ("node differs from symtab decl hashtable");
+	  error ("node differs from node->decl->decl_with_vis.symtab_node");
 	  error_found = true;
 	}
     }
@@ -832,12 +751,12 @@  verify_symtab_base (symtab_node *node)
     {
       symtab_node *n = node->same_comdat_group;
 
-      if (!DECL_COMDAT_GROUP (n->decl))
+      if (!n->get_comdat_group ())
 	{
-	  error ("node is in same_comdat_group list but has no DECL_COMDAT_GROUP");
+	  error ("node is in same_comdat_group list but has no comdat_group");
 	  error_found = true;
 	}
-      if (DECL_COMDAT_GROUP (n->decl) != DECL_COMDAT_GROUP (node->same_comdat_group->decl))
+      if (n->get_comdat_group () != node->get_comdat_group ())
 	{
 	  error ("same_comdat_group list across different groups");
 	  error_found = true;
@@ -950,7 +869,7 @@  symtab_make_decl_local (tree decl)
 {
   rtx rtl, symbol;
 
-  /* Avoid clearing DECL_COMDAT_GROUP on comdat-local decls.  */
+  /* Avoid clearing comdat_groups on comdat-local decls.  */
   if (TREE_PUBLIC (decl) == 0)
     return;
 
@@ -958,12 +877,11 @@  symtab_make_decl_local (tree decl)
     DECL_COMMON (decl) = 0;
   else gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
 
-  if (DECL_COMDAT_GROUP (decl) || DECL_COMDAT (decl))
+  if (DECL_COMDAT (decl))
     {
       DECL_SECTION_NAME (decl) = 0;
       DECL_COMDAT (decl) = 0;
     }
-  DECL_COMDAT_GROUP (decl) = 0;
   DECL_WEAK (decl) = 0;
   DECL_EXTERNAL (decl) = 0;
   DECL_VISIBILITY_SPECIFIED (decl) = 0;
@@ -1097,11 +1015,13 @@  fixup_same_cpp_alias_visibility (symtab_
   DECL_VIRTUAL_P (node->decl) = DECL_VIRTUAL_P (target->decl);
   if (TREE_PUBLIC (node->decl))
     {
+      tree group;
+
       DECL_EXTERNAL (node->decl) = DECL_EXTERNAL (target->decl);
       DECL_COMDAT (node->decl) = DECL_COMDAT (target->decl);
-      DECL_COMDAT_GROUP (node->decl)
-	 = DECL_COMDAT_GROUP (target->decl);
-      if (DECL_COMDAT_GROUP (target->decl)
+      group = target->get_comdat_group ();
+      node->set_comdat_group (group);
+      if (group
 	  && !node->same_comdat_group)
 	symtab_add_to_same_comdat_group (node, target);
     }
@@ -1231,9 +1151,6 @@  symtab_nonoverwritable_alias (symtab_nod
 
   /* Update the properties.  */
   DECL_EXTERNAL (new_decl) = 0;
-  if (DECL_COMDAT_GROUP (node->decl))
-    DECL_SECTION_NAME (new_decl) = NULL;
-  DECL_COMDAT_GROUP (new_decl) = 0;
   TREE_PUBLIC (new_decl) = 0;
   DECL_COMDAT (new_decl) = 0;
   DECL_WEAK (new_decl) = 0;
@@ -1246,8 +1163,7 @@  symtab_nonoverwritable_alias (symtab_nod
 				 (new_decl, node->decl);
     }
   else
-    new_node = varpool_create_variable_alias (new_decl,
-							    node->decl);
+    new_node = varpool_create_variable_alias (new_decl, node->decl);
   symtab_resolve_alias (new_node, node);  
   gcc_assert (decl_binds_to_current_def_p (new_decl));
   return new_node;
Index: cgraphclones.c
===================================================================
--- cgraphclones.c	(revision 210887)
+++ cgraphclones.c	(working copy)
@@ -283,7 +283,6 @@  static void
 set_new_clone_decl_and_node_flags (cgraph_node *new_node)
 {
   DECL_EXTERNAL (new_node->decl) = 0;
-  DECL_COMDAT_GROUP (new_node->decl) = 0;
   TREE_PUBLIC (new_node->decl) = 0;
   DECL_COMDAT (new_node->decl) = 0;
   DECL_WEAK (new_node->decl) = 0;
@@ -558,7 +557,7 @@  cgraph_create_virtual_clone (struct cgra
      that is not weak also.
      ??? We cannot use COMDAT linkage because there is no
      ABI support for this.  */
-  if (DECL_COMDAT_GROUP (old_decl))
+  if (old_node->get_comdat_group ())
     DECL_SECTION_NAME (new_node->decl) = NULL;
   set_new_clone_decl_and_node_flags (new_node);
   new_node->clone.tree_map = tree_map;
Index: ipa.c
===================================================================
--- ipa.c	(revision 210887)
+++ ipa.c	(working copy)
@@ -1021,13 +1021,13 @@  update_visibility_by_resolution_info (sy
     for (symtab_node *next = node->same_comdat_group;
 	 next != node; next = next->same_comdat_group)
       {
-	DECL_COMDAT_GROUP (next->decl) = NULL;
+	next->set_comdat_group (NULL);
 	DECL_WEAK (next->decl) = false;
 	if (next->externally_visible
 	    && !define)
 	  DECL_EXTERNAL (next->decl) = true;
       }
-  DECL_COMDAT_GROUP (node->decl) = NULL;
+  node->set_comdat_group (NULL);
   DECL_WEAK (node->decl) = false;
   if (!define)
     DECL_EXTERNAL (node->decl) = true;
@@ -1163,8 +1163,7 @@  function_and_variable_visibility (bool w
 	    {
 	      gcc_checking_assert (DECL_COMDAT (node->decl)
 				   == DECL_COMDAT (decl_node->decl));
-	      gcc_checking_assert (DECL_COMDAT_GROUP (node->decl)
-				   == DECL_COMDAT_GROUP (decl_node->decl));
+	      gcc_checking_assert (symtab_in_same_comdat_p (node, decl_node));
 	      gcc_checking_assert (node->same_comdat_group);
 	    }
 	  node->forced_by_abi = decl_node->forced_by_abi;
Index: bb-reorder.c
===================================================================
--- bb-reorder.c	(revision 210887)
+++ bb-reorder.c	(working copy)
@@ -99,6 +99,7 @@ 
 #include "tree-pass.h"
 #include "df.h"
 #include "bb-reorder.h"
+#include "cgraph.h"
 #include "except.h"
 
 /* The number of rounds.  In most cases there will only be 4 rounds, but
Index: lto-streamer-out.c
===================================================================
--- lto-streamer-out.c	(revision 210887)
+++ lto-streamer-out.c	(working copy)
@@ -535,7 +535,6 @@  DFS_write_tree_body (struct output_block
       if (DECL_ASSEMBLER_NAME_SET_P (expr))
 	DFS_follow_tree_edge (DECL_ASSEMBLER_NAME (expr));
       DFS_follow_tree_edge (DECL_SECTION_NAME (expr));
-      DFS_follow_tree_edge (DECL_COMDAT_GROUP (expr));
     }
 
   if (CODE_CONTAINS_STRUCT (code, TS_FIELD_DECL))
@@ -974,7 +973,6 @@  hash_tree (struct streamer_tree_cache_d
       if (DECL_ASSEMBLER_NAME_SET_P (t))
 	visit (DECL_ASSEMBLER_NAME (t));
       visit (DECL_SECTION_NAME (t));
-      visit (DECL_COMDAT_GROUP (t));
     }
 
   if (CODE_CONTAINS_STRUCT (code, TS_FIELD_DECL))
Index: ipa-comdats.c
===================================================================
--- ipa-comdats.c	(revision 210887)
+++ ipa-comdats.c	(working copy)
@@ -202,8 +202,8 @@  set_comdat_group (symtab_node *symbol,
 {
   symtab_node *head = (symtab_node *)head_p;
 
-  gcc_assert (!DECL_COMDAT_GROUP (symbol->decl));
-  DECL_COMDAT_GROUP (symbol->decl) = DECL_COMDAT_GROUP (head->decl);
+  gcc_assert (!symbol->get_comdat_group ());
+  symbol->set_comdat_group (head->get_comdat_group ());
   symtab_add_to_same_comdat_group (symbol, head);
   return false;
 }
@@ -218,6 +218,7 @@  ipa_comdats (void)
   symtab_node *symbol;
   bool comdat_group_seen = false;
   symtab_node *first = (symtab_node *) (void *) 1;
+  tree group;
 
   /* Start the dataflow by assigning comdat group to symbols that are in comdat
      groups already.  All other externally visible symbols must stay, we use
@@ -226,10 +227,10 @@  ipa_comdats (void)
   FOR_EACH_DEFINED_SYMBOL (symbol)
     if (!symtab_real_symbol_p (symbol))
       ;
-    else if (DECL_COMDAT_GROUP (symbol->decl))
+    else if ((group = symbol->get_comdat_group ()) != NULL)
       {
-        *map.insert (symbol) = DECL_COMDAT_GROUP (symbol->decl);
-        *comdat_head_map.insert (DECL_COMDAT_GROUP (symbol->decl)) = symbol;
+        *map.insert (symbol) = group;
+        *comdat_head_map.insert (group) = symbol;
 	comdat_group_seen = true;
 
 	/* Mark the symbol so we won't waste time visiting it for dataflow.  */
@@ -313,7 +314,7 @@  ipa_comdats (void)
   FOR_EACH_DEFINED_SYMBOL (symbol)
     {
       symbol->aux = NULL; 
-      if (!DECL_COMDAT_GROUP (symbol->decl)
+      if (!symbol->get_comdat_group ()
 	  && !symbol->alias
 	  && symtab_real_symbol_p (symbol))
 	{
Index: cgraph.c
===================================================================
--- cgraph.c	(revision 210887)
+++ cgraph.c	(working copy)
@@ -565,7 +565,7 @@  cgraph_get_create_node (tree decl)
       first_clone->clone_of = node;
       node->clones = first_clone;
       symtab_prevail_in_asm_name_hash (node);
-      symtab_insert_node_to_hashtable (node);
+      node->decl->decl_with_vis.symtab_node = node;
       if (dump_file)
 	fprintf (dump_file, "Introduced new external node "
 		 "(%s/%i) and turned into root of the clone tree.\n",
Index: cgraph.h
===================================================================
--- cgraph.h	(revision 210887)
+++ cgraph.h	(working copy)
@@ -141,6 +141,18 @@  public:
   /* Circular list of nodes in the same comdat group if non-NULL.  */
   symtab_node *same_comdat_group;
 
+  /* Return comdat group.  */
+  tree get_comdat_group ()
+    {
+      return comdat_group_;
+    }
+
+  /* Set comdat group.  */
+  void set_comdat_group (tree group)
+    {
+      comdat_group_ = group;
+    }
+
   /* Vectors of referring and referenced entities.  */
   struct ipa_ref_list ref_list;
 
@@ -153,6 +165,9 @@  public:
   struct lto_file_decl_data * lto_file_data;
 
   PTR GTY ((skip)) aux;
+
+  /* Comdat group the symbol is in.  Can be private if GGC allowed that.  */
+  tree comdat_group_;
 };
 
 enum availability
@@ -727,9 +742,7 @@  void symtab_register_node (symtab_node *
 void symtab_unregister_node (symtab_node *);
 void symtab_remove_from_same_comdat_group (symtab_node *);
 void symtab_remove_node (symtab_node *);
-symtab_node *symtab_get_node (const_tree);
 symtab_node *symtab_node_for_asm (const_tree asmname);
-void symtab_insert_node_to_hashtable (symtab_node *);
 void symtab_add_to_same_comdat_group (symtab_node *, symtab_node *);
 void symtab_dissolve_same_comdat_group_list (symtab_node *node);
 void dump_symtab (FILE *);
@@ -989,6 +1002,28 @@  void varpool_remove_initializer (varpool
 /* In cgraph.c */
 extern void change_decl_assembler_name (tree, tree);
 
+/* Return symbol table node associated with DECL, if any,
+   and NULL otherwise.  */
+
+static inline symtab_node *
+symtab_get_node (const_tree decl)
+{
+#ifdef ENABLE_CHECKING
+  /* Check that we are called for sane type of object - functions
+     and static or external variables.  */
+  gcc_checking_assert (TREE_CODE (decl) == FUNCTION_DECL
+		       || (TREE_CODE (decl) == VAR_DECL
+			   && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)
+			       || in_lto_p)));
+  /* Check that the mapping is sane - perhaps this check can go away,
+     but at the moment frontends tends to corrupt the mapping by calling
+     memcpy/memset on the tree nodes.  */
+  gcc_checking_assert (!decl->decl_with_vis.symtab_node
+		       || decl->decl_with_vis.symtab_node->decl == decl);
+#endif
+  return decl->decl_with_vis.symtab_node;
+}
+
 /* Return callgraph node for given symbol and check it is a function. */
 static inline struct cgraph_node *
 cgraph (symtab_node *node)
@@ -1548,7 +1583,7 @@  static inline bool
 symtab_can_be_discarded (symtab_node *node)
 {
   return (DECL_EXTERNAL (node->decl)
-	  || (DECL_ONE_ONLY (node->decl)
+	  || (node->get_comdat_group ()
 	      && node->resolution != LDPR_PREVAILING_DEF
 	      && node->resolution != LDPR_PREVAILING_DEF_IRONLY
 	      && node->resolution != LDPR_PREVAILING_DEF_IRONLY_EXP));
@@ -1580,6 +1615,16 @@  symtab_in_same_comdat_p (symtab_node *on
 	two = cn->global.inlined_to;
     }
 
-  return DECL_COMDAT_GROUP (one->decl) == DECL_COMDAT_GROUP (two->decl);
+  return one->get_comdat_group () == two->get_comdat_group ();
+}
+
+/* Return comdat group of DECL.  */
+static inline tree
+decl_comdat_group (tree node)
+{
+  struct symtab_node *snode = symtab_get_node (node);
+  if (!snode)
+    return NULL;
+  return snode->get_comdat_group ();
 }
 #endif  /* GCC_CGRAPH_H  */
Index: tree-streamer-in.c
===================================================================
--- tree-streamer-in.c	(revision 210887)
+++ tree-streamer-in.c	(working copy)
@@ -760,7 +760,6 @@  lto_input_ts_decl_with_vis_tree_pointers
     }
 
   DECL_SECTION_NAME (expr) = stream_read_tree (ib, data_in);
-  DECL_COMDAT_GROUP (expr) = stream_read_tree (ib, data_in);
 }
 
 
Index: lto-cgraph.c
===================================================================
--- lto-cgraph.c	(revision 210887)
+++ lto-cgraph.c	(working copy)
@@ -395,6 +395,8 @@  lto_output_node (struct lto_simple_outpu
   ipa_opt_pass_d *pass;
   int i;
   bool alias_p;
+  const char *comdat;
+  tree group;
 
   boundary_p = !lto_symtab_encoder_in_partition_p (encoder, node);
 
@@ -478,15 +480,24 @@  lto_output_node (struct lto_simple_outpu
       streamer_write_hwi_stream (ob->main_stream, ref);
     }
 
-  if (node->same_comdat_group && !boundary_p)
+  group = node->get_comdat_group ();
+  if (group)
+    comdat = IDENTIFIER_POINTER (group);
+  else
+    comdat = "";
+  lto_output_data_stream (ob->main_stream, comdat, strlen (comdat) + 1);
+  if (group)
     {
-      ref = lto_symtab_encoder_lookup (encoder,
-				       node->same_comdat_group);
-      gcc_assert (ref != LCC_NOT_FOUND);
+      if (node->same_comdat_group && !boundary_p)
+	{
+	  ref = lto_symtab_encoder_lookup (encoder,
+					   node->same_comdat_group);
+	  gcc_assert (ref != LCC_NOT_FOUND);
+	}
+      else
+	ref = LCC_NOT_FOUND;
+      streamer_write_hwi_stream (ob->main_stream, ref);
     }
-  else
-    ref = LCC_NOT_FOUND;
-  streamer_write_hwi_stream (ob->main_stream, ref);
 
   streamer_write_hwi_stream (ob->main_stream, node->tp_first_run);
 
@@ -551,6 +562,8 @@  lto_output_varpool_node (struct lto_simp
   struct bitpack_d bp;
   int ref;
   bool alias_p;
+  const char *comdat;
+  tree group;
 
   streamer_write_enum (ob->main_stream, LTO_symtab_tags, LTO_symtab_last_tag,
 		       LTO_symtab_variable);
@@ -587,15 +600,24 @@  lto_output_varpool_node (struct lto_simp
 	  /* in_other_partition.  */
     }
   streamer_write_bitpack (&bp);
-  if (node->same_comdat_group && !boundary_p)
+  group = node->get_comdat_group ();
+  if (group)
+    comdat = IDENTIFIER_POINTER (group);
+  else
+    comdat = "";
+  lto_output_data_stream (ob->main_stream, comdat, strlen (comdat) + 1);
+  if (group)
     {
-      ref = lto_symtab_encoder_lookup (encoder,
-				       node->same_comdat_group);
-      gcc_assert (ref != LCC_NOT_FOUND);
+      if (node->same_comdat_group && !boundary_p)
+	{
+	  ref = lto_symtab_encoder_lookup (encoder,
+					   node->same_comdat_group);
+	  gcc_assert (ref != LCC_NOT_FOUND);
+	}
+      else
+	ref = LCC_NOT_FOUND;
+      streamer_write_hwi_stream (ob->main_stream, ref);
     }
-  else
-    ref = LCC_NOT_FOUND;
-  streamer_write_hwi_stream (ob->main_stream, ref);
   streamer_write_enum (ob->main_stream, ld_plugin_symbol_resolution,
 		       LDPR_NUM_KNOWN, node->resolution);
 }
@@ -946,6 +968,26 @@  output_symtab (void)
   output_refs (encoder);
 }
 
+/* Return COMDAT_GROUP encoded in IB as a plain string.  */
+
+static tree
+read_comdat_group (struct lto_input_block *ib)
+{
+  unsigned int len = strnlen (ib->data + ib->p, ib->len - ib->p - 1);
+  tree group;
+
+  if (ib->data[ib->p + len])
+    lto_section_overrun (ib);
+  if (!len)
+    {
+      ib->p++;
+      return NULL;
+    }
+  group = get_identifier (ib->data + ib->p);
+  ib->p += len;
+  return group;
+}
+
 /* Overwrite the information in NODE based on FILE_DATA, TAG, FLAGS,
    STACK_SIZE, SELF_TIME and SELF_SIZE.  This is called either to initialize
    NODE or to replace the values in it, for instance because the first
@@ -1034,6 +1076,7 @@  input_node (struct lto_file_decl_data *f
   int clone_ref;
   int order;
   int i, count;
+  tree group;
 
   order = streamer_read_hwi (ib) + order_base;
   clone_ref = streamer_read_hwi (ib);
@@ -1079,7 +1122,9 @@  input_node (struct lto_file_decl_data *f
   if (tag == LTO_symtab_analyzed_node)
     ref = streamer_read_hwi (ib);
 
-  ref2 = streamer_read_hwi (ib);
+  group = read_comdat_group (ib);
+  if (group)
+    ref2 = streamer_read_hwi (ib);
 
   /* Make sure that we have not read this node before.  Nodes that
      have already been read will have their tag stored in the 'aux'
@@ -1098,8 +1143,14 @@  input_node (struct lto_file_decl_data *f
   /* Store a reference for now, and fix up later to be a pointer.  */
   node->global.inlined_to = (cgraph_node_ptr) (intptr_t) ref;
 
-  /* Store a reference for now, and fix up later to be a pointer.  */
-  node->same_comdat_group = (symtab_node *) (intptr_t) ref2;
+  if (group)
+    {
+      node->set_comdat_group (group);
+      /* Store a reference for now, and fix up later to be a pointer.  */
+      node->same_comdat_group = (symtab_node *) (intptr_t) ref2;
+    }
+  else
+    node->same_comdat_group = (symtab_node *) (intptr_t) LCC_NOT_FOUND;
 
   if (node->thunk.thunk_p)
     {
@@ -1131,6 +1182,7 @@  input_varpool_node (struct lto_file_decl
   struct bitpack_d bp;
   int ref = LCC_NOT_FOUND;
   int order;
+  tree group;
 
   order = streamer_read_hwi (ib) + order_base;
   decl_index = streamer_read_uhwi (ib);
@@ -1168,9 +1220,16 @@  input_varpool_node (struct lto_file_decl
     }
   if (node->alias && !node->analyzed && node->weakref)
     node->alias_target = get_alias_symbol (node->decl);
-  ref = streamer_read_hwi (ib);
-  /* Store a reference for now, and fix up later to be a pointer.  */
-  node->same_comdat_group = (symtab_node *) (intptr_t) ref;
+  group = read_comdat_group (ib);
+  if (group)
+    {
+      node->set_comdat_group (group);
+      ref = streamer_read_hwi (ib);
+      /* Store a reference for now, and fix up later to be a pointer.  */
+      node->same_comdat_group = (symtab_node *) (intptr_t) ref;
+    }
+  else
+    node->same_comdat_group = (symtab_node *) (intptr_t) LCC_NOT_FOUND;
   node->resolution = streamer_read_enum (ib, ld_plugin_symbol_resolution,
 					        LDPR_NUM_KNOWN);
   gcc_assert (flag_ltrans
Index: c/c-decl.c
===================================================================
--- c/c-decl.c	(revision 210887)
+++ c/c-decl.c	(working copy)
@@ -2507,8 +2507,18 @@  merge_decls (tree newdecl, tree olddecl,
     switch (TREE_CODE (olddecl))
       {
       case FUNCTION_DECL:
-      case FIELD_DECL:
       case VAR_DECL:
+	{
+	  struct symtab_node *snode = olddecl->decl_with_vis.symtab_node;
+
+	  memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
+		  (char *) newdecl + sizeof (struct tree_decl_common),
+		  tree_code_size (TREE_CODE (olddecl)) - sizeof (struct tree_decl_common));
+	  olddecl->decl_with_vis.symtab_node = snode;
+	  break;
+	}
+
+      case FIELD_DECL:
       case PARM_DECL:
       case LABEL_DECL:
       case RESULT_DECL:
@@ -2561,6 +2571,9 @@  duplicate_decls (tree newdecl, tree oldd
     }
 
   merge_decls (newdecl, olddecl, newtype, oldtype);
+
+  /* The NEWDECL will no longer be needed.  */
+  ggc_free (newdecl);
   return true;
 }
 
Index: trans-mem.c
===================================================================
--- trans-mem.c	(revision 210887)
+++ trans-mem.c	(working copy)
@@ -4852,7 +4852,7 @@  ipa_tm_create_version_alias (struct cgra
 
   /* Perform the same remapping to the comdat group.  */
   if (DECL_ONE_ONLY (new_decl))
-    DECL_COMDAT_GROUP (new_decl) = tm_mangle (DECL_COMDAT_GROUP (old_decl));
+    varpool_get_node (new_decl)->set_comdat_group (tm_mangle (DECL_COMDAT_GROUP (old_decl)));
 
   new_node = cgraph_same_body_alias (NULL, new_decl, info->new_decl);
   new_node->tm_clone = true;
@@ -4892,7 +4892,7 @@  ipa_tm_create_version (struct cgraph_nod
 
   /* Perform the same remapping to the comdat group.  */
   if (DECL_ONE_ONLY (new_decl))
-    DECL_COMDAT_GROUP (new_decl) = tm_mangle (DECL_COMDAT_GROUP (old_decl));
+    varpool_get_node (new_decl)->set_comdat_group (tm_mangle (DECL_COMDAT_GROUP (old_decl)));
 
   gcc_assert (!old_node->ipa_transforms_to_apply.exists ());
   new_node = cgraph_copy_node_for_versioning (old_node, new_decl, vNULL, NULL);
Index: config/mips/mips.c
===================================================================
--- config/mips/mips.c	(revision 210887)
+++ config/mips/mips.c	(working copy)
@@ -6275,7 +6275,7 @@  mips_start_unique_function (const char *
   TREE_PUBLIC (decl) = 1;
   TREE_STATIC (decl) = 1;
 
-  DECL_COMDAT_GROUP (decl) = DECL_ASSEMBLER_NAME (decl);
+  cgraph_create_node (decl)->set_comdat_group (DECL_ASSEMBLER_NAME (decl));
 
   targetm.asm_out.unique_section (decl, 0);
   switch_to_section (get_named_section (decl, NULL, 0));
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 210887)
+++ config/i386/i386.c	(working copy)
@@ -9183,7 +9183,7 @@  ix86_code_end (void)
 #endif
       if (USE_HIDDEN_LINKONCE)
 	{
-	  DECL_COMDAT_GROUP (decl) = DECL_ASSEMBLER_NAME (decl);
+	  cgraph_create_node (decl)->set_comdat_group (DECL_ASSEMBLER_NAME (decl));
 
 	  targetm.asm_out.unique_section (decl, 0);
 	  switch_to_section (get_named_section (decl, NULL, 0));
Index: config/rs6000/rs6000.c
===================================================================
--- config/rs6000/rs6000.c	(revision 210887)
+++ config/rs6000/rs6000.c	(working copy)
@@ -32331,7 +32331,7 @@  rs6000_code_end (void)
 #if RS6000_WEAK
   if (USE_HIDDEN_LINKONCE)
     {
-      DECL_COMDAT_GROUP (decl) = DECL_ASSEMBLER_NAME (decl);
+      cgraph_create_node (decl)->set_comdat_group (DECL_ASSEMBLER_NAME (decl));
       targetm.asm_out.unique_section (decl, 0);
       switch_to_section (get_named_section (decl, NULL, 0));
       DECL_WEAK (decl) = 1;
Index: lto/lto-symtab.c
===================================================================
--- lto/lto-symtab.c	(revision 210887)
+++ lto/lto-symtab.c	(working copy)
@@ -644,7 +644,7 @@  lto_symtab_merge_symbols (void)
 		       && cnode2 != cnode)
 		cgraph_remove_node (cnode2);
 
-	      symtab_insert_node_to_hashtable (node);
+	      node->decl->decl_with_vis.symtab_node = node;
 	    }
 	}
     }
Index: lto/lto.c
===================================================================
--- lto/lto.c	(revision 210887)
+++ lto/lto.c	(working copy)
@@ -1530,7 +1530,6 @@  compare_tree_sccs_1 (tree t1, tree t2, t
 	compare_tree_edges (DECL_ASSEMBLER_NAME (t1),
 			    DECL_ASSEMBLER_NAME (t2));
       compare_tree_edges (DECL_SECTION_NAME (t1), DECL_SECTION_NAME (t2));
-      compare_tree_edges (DECL_COMDAT_GROUP (t1), DECL_COMDAT_GROUP (t2));
     }
 
   if (CODE_CONTAINS_STRUCT (code, TS_FIELD_DECL))
Index: tree-streamer-out.c
===================================================================
--- tree-streamer-out.c	(revision 210887)
+++ tree-streamer-out.c	(working copy)
@@ -662,7 +662,6 @@  write_ts_decl_with_vis_tree_pointers (st
     stream_write_tree (ob, NULL_TREE, false);
 
   stream_write_tree (ob, DECL_SECTION_NAME (expr), ref_p);
-  stream_write_tree (ob, DECL_COMDAT_GROUP (expr), ref_p);
 }