re PR middle-end/49465 (Revision 175114 miscompiled 403.gcc in SPEC CPU 2006)

	PR middle-end/49465
	* tree-ssa-threadupate.c (fix_duplicate_block_edges): Fix condition
	to detect threading through joiner block.  If there was already
	an edge to the new target, then do not change the PHI nodes.

*************** fix_duplicate_block_edges (struct redire

From-SVN: r175351

gcc/ChangeLog

+2011-06-16  Jeff Law  <law@redhat.com>
+
+	PR middle-end/49465
+	* tree-ssa-threadupate.c (fix_duplicate_block_edges): Fix condition
+	to detect threading through joiner block.  If there was already
+	an edge to the new target, then do not change the PHI nodes.
+
 2011-06-23  Jakub Jelinek  <jakub@redhat.com>
 
 	* tree-vect-data-refs.c (vect_compute_data_ref_alignment): Use

gcc/tree-ssa-threadupdate.c

@@ -385,7 +385,7 @@ fix_duplicate_block_edges (struct redirection_data *rd,
      to keep its control statement and redirect an outgoing edge.
      Else we want to remove the control statement & edges, then create
      a new outgoing edge.  In both cases we may need to update PHIs.  */
-  if (THREAD_TARGET2 (rd->incoming_edges->e) == rd->outgoing_edge)
+  if (THREAD_TARGET2 (rd->incoming_edges->e))
     {
       edge victim;
       edge e2;
@@ -400,8 +400,11 @@ fix_duplicate_block_edges (struct redirection_data *rd,
       victim = find_edge (rd->dup_block, THREAD_TARGET (e)->dest);
       e2 = redirect_edge_and_branch (victim, THREAD_TARGET2 (e)->dest);
 
-      /* This updates the PHI at the target of the threaded edge.  */
-      copy_phi_args (e2->dest, THREAD_TARGET2 (e), e2);
+      /* If we redirected the edge, then we need to copy PHI arguments
+	 at the target.  If the edge already existed (e2 != victim case),
+	 then the PHIs in the target already have the correct arguments.  */
+      if (e2 == victim)
+	copy_phi_args (e2->dest, THREAD_TARGET2 (e), e2);
     }
   else
     {