--- a/hotspot/src/share/vm/memory/memRegion.hpp	Fri Aug 31 16:39:35 2012 -0700
+++ b/hotspot/src/share/vm/memory/memRegion.hpp	Sat Sep 01 13:25:18 2012 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2012, 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
@@ -36,6 +36,8 @@
 // The intent is that they remain very small and contain no
 // objects.
 
+class MetaWord;
+
 class MemRegion VALUE_OBJ_CLASS_SPEC {
   friend class VMStructs;
 private:
@@ -50,6 +52,10 @@
     _start(start), _word_size(pointer_delta(end, start)) {
     assert(end >= start, "incorrect constructor arguments");
   }
+  MemRegion(MetaWord* start, MetaWord* end) :
+    _start((HeapWord*)start), _word_size(pointer_delta(end, start)) {
+    assert(end >= start, "incorrect constructor arguments");
+  }
 
   MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}