diff -r 6a8ccac44f41 -r 54b3b351d6f9 src/share/vm/gc_implementation/shared/markSweep.cpp
--- a/src/share/vm/gc_implementation/shared/markSweep.cpp	Fri Sep 18 09:57:47 2009 -0700
+++ b/src/share/vm/gc_implementation/shared/markSweep.cpp	Wed Sep 23 23:56:15 2009 -0700
@@ -27,6 +27,7 @@
 
 GrowableArray<oop>*     MarkSweep::_marking_stack       = NULL;
 GrowableArray<Klass*>*  MarkSweep::_revisit_klass_stack = NULL;
+GrowableArray<DataLayout*>*  MarkSweep::_revisit_mdo_stack = NULL;
 
 GrowableArray<oop>*     MarkSweep::_preserved_oop_stack = NULL;
 GrowableArray<markOop>* MarkSweep::_preserved_mark_stack= NULL;
@@ -62,12 +63,37 @@
 void MarkSweep::follow_weak_klass_links() {
   // All klasses on the revisit stack are marked at this point.
   // Update and follow all subklass, sibling and implementor links.
+  if (PrintRevisitStats) {
+    gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
+    gclog_or_tty->print_cr("Revisit klass stack length = %d", _revisit_klass_stack->length());
+  }
   for (int i = 0; i < _revisit_klass_stack->length(); i++) {
     _revisit_klass_stack->at(i)->follow_weak_klass_links(&is_alive,&keep_alive);
   }
   follow_stack();
 }
 
+#if ( defined(COMPILER1) || defined(COMPILER2) )
+void MarkSweep::revisit_mdo(DataLayout* p) {
+  _revisit_mdo_stack->push(p);
+}
+
+void MarkSweep::follow_mdo_weak_refs() {
+  // All strongly reachable oops have been marked at this point;
+  // we can visit and clear any weak references from MDO's which
+  // we memoized during the strong marking phase.
+  assert(_marking_stack->is_empty(), "Marking stack should be empty");
+  if (PrintRevisitStats) {
+    gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
+    gclog_or_tty->print_cr("Revisit MDO stack length = %d", _revisit_mdo_stack->length());
+  }
+  for (int i = 0; i < _revisit_mdo_stack->length(); i++) {
+    _revisit_mdo_stack->at(i)->follow_weak_refs(&is_alive);
+  }
+  follow_stack();
+}
+#endif //  ( COMPILER1 || COMPILER2 )
+
 MarkSweep::FollowRootClosure  MarkSweep::follow_root_closure;
 CodeBlobToOopClosure MarkSweep::follow_code_root_closure(&MarkSweep::follow_root_closure, /*do_marking=*/ true);