*** old/agent/src/share/classes/sun/jvm/hotspot/oops/OopField.java	Fri Mar 18 14:59:17 2011
--- new/agent/src/share/classes/sun/jvm/hotspot/oops/OopField.java	Fri Mar 18 14:59:17 2011

*** 1,7 ****
--- 1,7 ----
  /*
!  * Copyright (c) 2000, 2002, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

*** 39,53 ****
--- 39,59 ----
    public OopField(InstanceKlass holder, int fieldArrayIndex) {
      super(holder, fieldArrayIndex);
    }
  
    public Oop getValue(Oop obj) {
+     if (!isVMField() && !obj.isInstance() && !obj.isArray()) {
+       throw new InternalError();
+     }
      return obj.getHeap().newOop(getValueAsOopHandle(obj));
    }
  
    /** Debugging support */
    public OopHandle getValueAsOopHandle(Oop obj) {
+     if (!isVMField() && !obj.isInstance() && !obj.isArray()) {
+       throw new InternalError(obj.toString());
+     }
      return obj.getHandle().getOopHandleAt(getOffset());
    }
  
    public void setValue(Oop obj) throws MutationException {
      // Fix this: setOopAt is missing in Address