--- old/src/share/vm/opto/loopUnswitch.cpp	Tue Apr  8 13:23:41 2008
+++ new/src/share/vm/opto/loopUnswitch.cpp	Tue Apr  8 13:23:40 2008
@@ -51,6 +51,9 @@
   if( !LoopUnswitching ) {
     return false;
   }
+  if (!_head->is_Loop()) {
+    return false; 
+  }
   uint nodes_left = MaxNodeLimit - phase->C->unique();
   if (2 * _body.size() > nodes_left) {
     return false; // Too speculative if running low on nodes.
--- old/src/share/vm/opto/loopopts.cpp	Tue Apr  8 13:23:43 2008
+++ new/src/share/vm/opto/loopopts.cpp	Tue Apr  8 13:23:42 2008
@@ -2257,6 +2257,10 @@
 //
 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
 
+  if (!loop->_head->is_Loop()) {
+    return false; 
+  }
+
   LoopNode *head  = loop->_head->as_Loop();
 
   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {