[PATCH] Fix PR46504

[Richard Guenther <rguenther@suse.de>]

When introducing canonical type merging I forgot about the interaction
with regular type merging.  The following patch makes sure that we
have only merging leaders as canonical types.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

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.

Index: gcc/gimple.c
===================================================================
*** gcc/gimple.c	(revision 166860)
--- gcc/gimple.c	(working copy)
*************** gimple_register_canonical_type (tree t)
*** 4398,4403 ****
--- 4398,4407 ----
    if (TYPE_CANONICAL (t))
      return TYPE_CANONICAL (t);
  
+   /* Always register the type itself first so that the canonical type
+      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.  */