diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0108a0d3a7b3..acdfadb50eba 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+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.
+
 2012-08-12  Jan Hubicka  <jh@suse.cz>
 
 	* tree-pass.h (write_summary, write_optimization_summary): Remove
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a9df8b75264a..f09347af0d75 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2012-08-13  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/54200
+	* gcc.dg/guality/pr54200.c: New testcase.
+	* gcc.dg/tree-ssa/slsr-8.c: Adjust.
+
 2012-08-12  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	* gcc.target/sh/prefetch.c: Add -m3* to inclusion list.
diff --git a/gcc/testsuite/gcc.dg/guality/pr54200.c b/gcc/testsuite/gcc.dg/guality/pr54200.c
new file mode 100644
index 000000000000..9b171876401c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/guality/pr54200.c
@@ -0,0 +1,28 @@
+/* PR tree-optimization/54200 */
+/* { dg-do run } */
+/* { dg-options "-g -fno-var-tracking-assignments" } */
+
+int o __attribute__((used));
+
+void bar (void) { o = 2; }
+
+int __attribute__((noinline,noclone))
+foo (int z, int x, int b)
+{
+  if (x == 1)
+    {
+      bar ();
+      return z;
+    }
+  else
+    {
+      int a = (x + z) + b;
+      return a; /* { dg-final { gdb-test 20 "z" "3" } } */
+    }
+}
+
+int main ()
+{
+  foo (3, 2, 1);
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/slsr-8.c b/gcc/testsuite/gcc.dg/tree-ssa/slsr-8.c
index b03c52c33603..c2e9b615568d 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/slsr-8.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/slsr-8.c
@@ -17,7 +17,7 @@ f (int s, int *c)
   return x1 ? x2 : x3;
 }
 
-/* There are 2 ' * ' instances in the decls (since "int * x3;" is
-   optimized out), 1 parm, 2 in the code.  */
-/* { dg-final { scan-tree-dump-times " \\* " 5 "optimized" } } */
+/* There are 4 ' * ' instances in the decls (since "int * iftmp.0;" is
+   added), 1 parm, 2 in the code.  */
+/* { dg-final { scan-tree-dump-times " \\* " 7 "optimized" } } */
 /* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/tree-ssa-copyrename.c b/gcc/tree-ssa-copyrename.c
index 82f8c64fe1c7..387e67bce6e9 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);
+	    }
         }
     }