[Bug middle-end/57366] gcc.dg/lto/attr-weakref-1 FAILs

["hubicka at ucw dot cz" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57366

--- Comment #14 from Jan Hubicka <hubicka at ucw dot cz> ---
Hi,
the problems with weakref are bit deeper than I though.  They way RTL rewriting
is done
breaks completely with any symbol renaming that is quite common with LTO.  I am
testing
the following

Index: cgraphunit.c
===================================================================
--- cgraphunit.c    (revision 199577)
+++ cgraphunit.c    (working copy)
@@ -1996,6 +1996,32 @@ compile (void)
   bitmap_obstack_release (NULL);
   mark_functions_to_output ();

+  /* When weakref support is missing, we autmatically translate all
+     references to NODE to references to its ultimate alias target.
+     The renaming mechanizm uses flag IDENTIFIER_TRANSPARENT_ALIAS and
+     TREE_CHAIN.
+
+     Set up this mapping before we output any assembler but once we are sure
+     that all symbol renaming is done.
+
+     FIXME: All this uglyness can go away if we just do renaming at gimple
+     level by physically rewritting the IL.  At the moment we can only
redirect
+     calls, so we need infrastructure for renaming references as well.  */
+#ifndef ASM_OUTPUT_WEAKREF
+  symtab_node node;
+
+  FOR_EACH_SYMBOL (node)
+    if (node->symbol.alias
+    && lookup_attribute ("weakref", DECL_ATTRIBUTES (node->symbol.decl)))
+      {
+    IDENTIFIER_TRANSPARENT_ALIAS
+       (DECL_ASSEMBLER_NAME (node->symbol.decl)) = 1;
+    TREE_CHAIN (DECL_ASSEMBLER_NAME (node->symbol.decl))
+       = (node->symbol.alias_target ? node->symbol.alias_target
+          : DECL_ASSEMBLER_NAME (symtab_alias_target (node)->symbol.decl));
+      }
+#endif
+
   cgraph_state = CGRAPH_STATE_EXPANSION;
   if (!flag_toplevel_reorder)
     output_in_order ();