diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b7704877055..1a7bb1eb2e7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-11-17  Richard Guenther  <rguenther@suse.de>
+
+	PR lto/46504
+	* gimple.c (gimple_register_canonical_type): Make sure to only
+	make type leaders canonical types.
+
 2010-11-17  Michael Matz  <matz@suse.de>
 
 	* timevar.def (TV_IPA_OPT, TV_EARLY_LOCAL, TV_OPTIMIZE,
diff --git a/gcc/gimple.c b/gcc/gimple.c
index 6704456c0cc..5f6b8d41c48 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -4398,6 +4398,10 @@ gimple_register_canonical_type (tree t)
   if (TYPE_CANONICAL (t))
     return TYPE_CANONICAL (t);
 
+  /* Always register the type itself first so that if it turns out
+     to be the canonical type it will be the one we merge to as well.  */
+  t = gimple_register_type (t);
+
   /* Always register the main variant first.  This is important so we
      pick up the non-typedef variants as canonical, otherwise we'll end
      up taking typedef ids for structure tags during comparison.  */