diff -r fde683df4c27 -r ee138854b3a6 src/share/vm/utilities/growableArray.hpp
--- a/src/share/vm/utilities/growableArray.hpp	Fri Mar 09 13:34:45 2012 -0800
+++ b/src/share/vm/utilities/growableArray.hpp	Mon Mar 12 10:46:47 2012 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -198,8 +198,11 @@
     return idx;
   }
 
-  void append_if_missing(const E& elem) {
-    if (!contains(elem)) append(elem);
+  bool append_if_missing(const E& elem) {
+    // Returns TRUE if elem is added.
+    bool missed = !contains(elem);
+    if (missed) append(elem);
+    return missed;
   }
 
   E at(int i) const {
@@ -292,12 +295,22 @@
     ShouldNotReachHere();
   }
 
+  // The order is preserved.
   void remove_at(int index) {
     assert(0 <= index && index < _len, "illegal index");
     for (int j = index + 1; j < _len; j++) _data[j-1] = _data[j];
     _len--;
   }
 
+  // The order is changed.
+  void delete_at(int index) {
+    assert(0 <= index && index < _len, "illegal index");
+    if (index < --_len) {
+      // Replace removed element with last one.
+      _data[index] = _data[_len];
+    }
+  }
+
   // inserts the given element before the element at index i
   void insert_before(const int idx, const E& elem) {
     check_nesting();