diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aa00c5d9b43..c4ea18dd6b5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2007-12-12  David Edelsohn  <edelsohn@gnu.org>
+
+	* config/rs6000/rs6000.c (is_mem_ref): Ignore STACK_TIE.
+
 2007-12-12  Aldy Hernandez  <aldyh@redhat.com>
 
 	PR tree-optimization/32901
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 5d6f9852c64..c730a65fc29 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -18383,6 +18383,11 @@ is_mem_ref (rtx pat)
   int i, j;
   bool ret = false;
 
+  /* stack_tie does not produce any real memory traffic.  */
+  if (GET_CODE (pat) == UNSPEC
+      && XINT (pat, 1) == UNSPEC_TIE)
+    return false;
+
   if (GET_CODE (pat) == MEM)
     return true;