diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5511a4bf95c..3f19c86b739 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2004-11-03  Kazu Hirata  <kazu@cs.umass.edu>
+
+	* tree-phinodes.c (resize_phi_node): Copy only a portion of
+	the PHI node currently in use.
+
 2004-11-03  Andrew Pinski  <pinskia@physics.uc.edu>
 
 	PR tree-opt/18231
diff --git a/gcc/tree-phinodes.c b/gcc/tree-phinodes.c
index ba46c786459..5c5be3f7742 100644
--- a/gcc/tree-phinodes.c
+++ b/gcc/tree-phinodes.c
@@ -254,9 +254,11 @@ resize_phi_node (tree *phi, int len)
 
   gcc_assert (len >= PHI_ARG_CAPACITY (*phi));
 
-  /* Note that OLD_SIZE is guaranteed to be smaller than SIZE.  */
+  /* The garbage collector will not look at the PHI node beyond the
+     first PHI_NUM_ARGS elements.  Therefore, all we have to copy is a
+     portion of the PHI node currently in use.  */
   old_size = (sizeof (struct tree_phi_node)
-	     + (PHI_ARG_CAPACITY (*phi) - 1) * sizeof (struct phi_arg_d));
+	     + (PHI_NUM_ARGS (*phi) - 1) * sizeof (struct phi_arg_d));
 
   new_phi = allocate_phi_node (len);