--- a/hotspot/src/share/vm/opto/chaitin.cpp	Mon Jun 18 12:29:21 2012 -0700
+++ b/hotspot/src/share/vm/opto/chaitin.cpp	Mon Jun 18 15:17:30 2012 -0700
@@ -1536,7 +1536,7 @@
 
   // Check for AddP-related opcodes
   if( !derived->is_Phi() ) {
-    assert( derived->as_Mach()->ideal_Opcode() == Op_AddP, "" );
+    assert(derived->as_Mach()->ideal_Opcode() == Op_AddP, err_msg("but is: %s", derived->Name()));
     Node *base = derived->in(AddPNode::Base);
     derived_base_map[derived->_idx] = base;
     return base;