2012-08-13 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/54200
	* tree-ssa-copyrename.c (rename_ssa_copies): Do not add
	PHI results to another partition if not all PHI arguments
	have the same partition.

	* gcc.dg/guality/pr54200.c: New testcase.
	* gcc.dg/tree-ssa/slsr-8.c: Adjust.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@190339 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 45 insertions, 7 deletions

diff --git a/gcc/tree-ssa-copyrename.c b/gcc/tree-ssa-copyrename.c
index 82f8c64fe1c..387e67bce6e 100644
--- a/gcc/tree-ssa-copyrename.c
+++ b/gcc/tree-ssa-copyrename.c
@@ -348,15 +348,53 @@ rename_ssa_copies (void)
 	  res = gimple_phi_result (phi);
 
 	  /* Do not process virtual SSA_NAMES.  */
-	  if (!is_gimple_reg (res))
+	  if (virtual_operand_p (res))
 	    continue;
 
-          for (i = 0; i < gimple_phi_num_args (phi); i++)
-            {
-              tree arg = gimple_phi_arg (phi, i)->def;
-              if (TREE_CODE (arg) == SSA_NAME)
-		updated |= copy_rename_partition_coalesce (map, res, arg, debug);
-            }
+	  /* Make sure to only use the same partition for an argument
+	     as the result but never the other way around.  */
+	  if (SSA_NAME_VAR (res)
+	      && !DECL_IGNORED_P (SSA_NAME_VAR (res)))
+	    for (i = 0; i < gimple_phi_num_args (phi); i++)
+	      {
+		tree arg = PHI_ARG_DEF (phi, i);
+		if (TREE_CODE (arg) == SSA_NAME)
+		  updated |= copy_rename_partition_coalesce (map, res, arg,
+							     debug);
+	      }
+	  /* Else if all arguments are in the same partition try to merge
+	     it with the result.  */
+	  else
+	    {
+	      int all_p_same = -1;
+	      int p = -1;
+	      for (i = 0; i < gimple_phi_num_args (phi); i++)
+		{
+		  tree arg = PHI_ARG_DEF (phi, i);
+		  if (TREE_CODE (arg) != SSA_NAME)
+		    {
+		      all_p_same = 0;
+		      break;
+		    }
+		  else if (all_p_same == -1)
+		    {
+		      p = partition_find (map->var_partition,
+					  SSA_NAME_VERSION (arg));
+		      all_p_same = 1;
+		    }
+		  else if (all_p_same == 1
+			   && p != partition_find (map->var_partition,
+						   SSA_NAME_VERSION (arg)))
+		    {
+		      all_p_same = 0;
+		      break;
+		    }
+		}
+	      if (all_p_same == 1)
+		updated |= copy_rename_partition_coalesce (map, res,
+							   PHI_ARG_DEF (phi, 0),
+							   debug);
+	    }
         }
     }