*** old/src/share/vm/opto/graphKit.cpp	Wed Jan 29 22:25:45 2014
--- new/src/share/vm/opto/graphKit.cpp	Wed Jan 29 22:25:44 2014

*** 2997,3006 ****
--- 2997,3011 ----
      region->del_req(_null_path);
      phi   ->del_req(_null_path);
    }
  
    Node* cast_obj = NULL;
+   if (tk->klass_is_exact()) {
+     // The following optimization tries to statically cast the speculative type of the object
+     // (for example obtained during profiling) to the type of the superklass and then do a
+     // dynamic check that the type of the object is what we expect. To work correctly
+     // for checkcast and aastore the type of superklass should be exact.
      const TypeOopPtr* obj_type = _gvn.type(obj)->is_oopptr();
      // We may not have profiling here or it may not help us. If we have
      // a speculative type use it to perform an exact cast.
      ciKlass* spec_obj_type = obj_type->speculative_type();
      if (spec_obj_type != NULL ||

*** 3015,3024 ****
--- 3020,3030 ----
            (*failure_control) = top();
          // adjust the type of the phi to the exact klass:
          phi->raise_bottom_type(_gvn.type(cast_obj)->meet_speculative(TypePtr::NULL_PTR));
        }
      }
+   }
  
    if (cast_obj == NULL) {
      // Load the object's klass
      Node* obj_klass = load_object_klass(not_null_obj);