--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/classfile/metadataOnStackMark.cpp	Wed Jan 23 10:34:29 2013 -0500
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2013, 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/metadataOnStackMark.hpp"
+#include "code/codeCache.hpp"
+#include "compiler/compileBroker.hpp"
+#include "oops/metadata.hpp"
+#include "runtime/synchronizer.hpp"
+#include "runtime/thread.hpp"
+#include "utilities/growableArray.hpp"
+
+
+// Keep track of marked on-stack metadata so it can be cleared.
+GrowableArray<Metadata*>* _marked_objects = NULL;
+NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)
+
+// Walk metadata on the stack and mark it so that redefinition doesn't delete
+// it.  Class unloading also walks the previous versions and might try to
+// delete it, so this class is used by class unloading also.
+MetadataOnStackMark::MetadataOnStackMark() {
+  assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
+  NOT_PRODUCT(_is_active = true;)
+  if (_marked_objects == NULL) {
+    _marked_objects = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(1000, true);
+  }
+  Threads::metadata_do(Metadata::mark_on_stack);
+  CodeCache::alive_nmethods_do(nmethod::mark_on_stack);
+  CompileBroker::mark_on_stack();
+}
+
+MetadataOnStackMark::~MetadataOnStackMark() {
+  assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
+  // Unmark everything that was marked.   Can't do the same walk because
+  // redefine classes messes up the code cache so the set of methods
+  // might not be the same.
+  for (int i = 0; i< _marked_objects->length(); i++) {
+    _marked_objects->at(i)->set_on_stack(false);
+  }
+  _marked_objects->clear();   // reuse growable array for next time.
+  NOT_PRODUCT(_is_active = false;)
+}
+
+// Record which objects are marked so we can unmark the same objects.
+void MetadataOnStackMark::record(Metadata* m) {
+  assert(_is_active, "metadata on stack marking is active");
+  _marked_objects->push(m);
+}