re PR tree-optimization/18307 (merge_pointed_to_info called incorrectly)

	PR tree-optimization/18307
	* tree-ssa-alias.c (merge_pointed_to_info): ICE if 'dest' and
	'orig' are the same node.
	(collect_points_to_info_r): Do not call merge_pointed_to_info
	when the PHI argument is identical to the LHS.

From-SVN: r90816

gcc/ChangeLog

+2004-11-17  Diego Novillo  <dnovillo@redhat.com>
+
+	PR tree-optimization/18307
+	* tree-ssa-alias.c (merge_pointed_to_info): ICE if 'dest' and
+	'orig' are the same node.
+	(collect_points_to_info_r): Do not call merge_pointed_to_info
+	when the PHI argument is identical to the LHS.
+
 2004-11-17  Steven Bosscher  <stevenb@suse.de>
 
 	* tree-ssa-propagate.c (cfg_blocks_add) Assert we're not trying

gcc/tree-ssa-alias.c

@@ -1697,12 +1697,8 @@ merge_pointed_to_info (struct alias_info *ai, tree dest, tree orig)
 {
   struct ptr_info_def *dest_pi, *orig_pi;
 
-  /* FIXME: It is erroneous to call this function with identical
-     nodes, however that currently occurs during bootstrap.  This check
-     stops further breakage.  PR 18307 documents the issue.  */
-  if (dest == orig)
-    return;
-  
+  gcc_assert (dest != orig);
+
   /* Make sure we have points-to information for ORIG.  */
   collect_points_to_info_for (ai, orig);
 
@@ -1938,7 +1934,9 @@ collect_points_to_info_r (tree var, tree stmt, void *data)
 	    break;
 	    
 	  case SSA_NAME:
-	    merge_pointed_to_info (ai, lhs, var);
+	    /* Avoid unnecessary merges.  */
+	    if (lhs != var)
+	      merge_pointed_to_info (ai, lhs, var);
 	    break;
 	    
 	  default: