defer C++ mangling aliases

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 9f9c4e3..4b27f5d 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@ 
+2015-05-08  Jason Merrill  <jason@redhat.com>
+
+	* decl2.c (mangling_aliases): New variable.
+	(note_mangling_alias, generate_mangling_aliases): New.
+	(cp_write_global_declarations): Call generate_mangling_aliases.
+	(generate_mangling_alias): Split out from...
+	* mangle.c (mangle_decl): ...here.
+	* cp-tree.h: Declare note_mangling_alias.
+
 2015-05-08  Aldy Hernandez  <aldyh@redhat.com>
 
 	* decl2.c (collect_candidates_for_java_method_aliases): Remove.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index e0fbf5e..4136d98 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5447,6 +5447,7 @@  extern tree finish_case_label			(location_t, tree, tree);
 extern tree cxx_maybe_build_cleanup		(tree, tsubst_flags_t);
 
 /* in decl2.c */
+extern void note_mangling_alias			(tree, tree);
 extern bool check_java_method			(tree);
 extern tree build_memfn_type			(tree, tree, cp_cv_quals, cp_ref_qualifier);
 extern tree build_pointer_ptrmemfn_type	(tree);
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index b3c98da..d435af2 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -118,6 +118,10 @@  static GTY(()) vec<tree, va_gc> *deferred_fns;
    sure are defined.  */
 static GTY(()) vec<tree, va_gc> *no_linkage_decls;
 
+/* A vector of alternating decls and identifiers, where the latter
+   is to be an alias for the former if the former is defined.  */
+static GTY(()) vec<tree, va_gc> *mangling_aliases;
+
 /* Nonzero if we're done parsing and into end-of-file activities.  */
 
 int at_eof;
@@ -4278,6 +4282,66 @@  handle_tls_init (void)
   expand_or_defer_fn (finish_function (0));
 }
 
+/* We're at the end of compilation, so generate any mangling aliases that
+   we've been saving up, if DECL is going to be output and ID2 isn't
+   already taken by another declaration.  */
+
+static void
+generate_mangling_alias (tree decl, tree id2)
+{
+  /* If there's a declaration already using this mangled name,
+     don't create a compatibility alias that conflicts.  */
+  if (IDENTIFIER_GLOBAL_VALUE (id2))
+    return;
+
+  struct cgraph_node *n = NULL;
+  if (TREE_CODE (decl) == FUNCTION_DECL
+      && !(n = cgraph_node::get (decl)))
+    /* Don't create an alias to an unreferenced function.  */
+    return;
+
+  tree alias = make_alias_for (decl, id2);
+  SET_IDENTIFIER_GLOBAL_VALUE (id2, alias);
+  DECL_IGNORED_P (alias) = 1;
+  TREE_PUBLIC (alias) = TREE_PUBLIC (decl);
+  DECL_VISIBILITY (alias) = DECL_VISIBILITY (decl);
+  if (vague_linkage_p (decl))
+    DECL_WEAK (alias) = 1;
+  if (TREE_CODE (decl) == FUNCTION_DECL)
+    n->create_same_body_alias (alias, decl);
+  else
+    varpool_node::create_extra_name_alias (alias, decl);
+}
+
+/* Note that we might want to emit an alias with the symbol ID2 for DECL at
+   the end of translation, for compatibility across bugs in the mangling
+   implementation.  */
+
+void
+note_mangling_alias (tree decl, tree id2)
+{
+#ifdef ASM_OUTPUT_DEF
+  if (at_eof)
+    generate_mangling_alias (decl, id2);
+  else
+    {
+      vec_safe_push (mangling_aliases, decl);
+      vec_safe_push (mangling_aliases, id2);
+    }
+#endif
+}
+
+static void
+generate_mangling_aliases ()
+{
+  while (!vec_safe_is_empty (mangling_aliases))
+    {
+      tree id2 = mangling_aliases->pop();
+      tree decl = mangling_aliases->pop();
+      generate_mangling_alias (decl, id2);
+    }
+}
+
 /* The entire file is now complete.  If requested, dump everything
    to a file.  */
 
@@ -4638,6 +4702,8 @@  cp_write_global_declarations (void)
     }
   while (reconsider);
 
+  generate_mangling_aliases ();
+
   /* All used inline functions must have a definition at this point.  */
   FOR_EACH_VEC_SAFE_ELT (deferred_fns, i, decl)
     {
diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index b0f72d1..647ec70 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -3554,30 +3554,7 @@  mangle_decl (const tree decl)
 		     flag_abi_compat_version, id2);
 	}
 
-#ifdef ASM_OUTPUT_DEF
-      /* If there's a declaration already using this mangled name,
-	 don't create a compatibility alias that conflicts.  */
-      if (IDENTIFIER_GLOBAL_VALUE (id2))
-	return;
-
-      struct cgraph_node *n = NULL;
-      if (TREE_CODE (decl) == FUNCTION_DECL
-	  && !(n = cgraph_node::get (decl)))
-	/* Don't create an alias to an unreferenced function.  */
-	return;
-
-      tree alias = make_alias_for (decl, id2);
-      SET_IDENTIFIER_GLOBAL_VALUE (id2, alias);
-      DECL_IGNORED_P (alias) = 1;
-      TREE_PUBLIC (alias) = TREE_PUBLIC (decl);
-      DECL_VISIBILITY (alias) = DECL_VISIBILITY (decl);
-      if (vague_linkage_p (decl))
-	DECL_WEAK (alias) = 1;
-      if (TREE_CODE (decl) == FUNCTION_DECL)
-	n->create_same_body_alias (alias, decl);
-      else
-	varpool_node::create_extra_name_alias (alias, decl);
-#endif
+      note_mangling_alias (decl, id2);
     }
 }