diff -r bb18957ad21e -r df6caf649ff7 src/share/vm/memory/referenceProcessor.cpp
--- a/src/share/vm/memory/referenceProcessor.cpp	Fri Jul 10 16:01:20 2009 -0700
+++ b/src/share/vm/memory/referenceProcessor.cpp	Tue Jul 14 15:40:39 2009 -0700
@@ -1013,12 +1013,19 @@
   // discovered_addr.
   oop current_head = refs_list.head();
 
-  // Note: In the case of G1, this pre-barrier is strictly
+  // Note: In the case of G1, this specific pre-barrier is strictly
   // not necessary because the only case we are interested in
-  // here is when *discovered_addr is NULL, so this will expand to
-  // nothing. As a result, I am just manually eliding this out for G1.
+  // here is when *discovered_addr is NULL (see the CAS further below),
+  // so this will expand to nothing. As a result, we have manually
+  // elided this out for G1, but left in the test for some future
+  // collector that might have need for a pre-barrier here.
   if (_discovered_list_needs_barrier && !UseG1GC) {
-    _bs->write_ref_field_pre((void*)discovered_addr, current_head); guarantee(false, "Needs to be fixed: YSR");
+    if (UseCompressedOops) {
+      _bs->write_ref_field_pre((narrowOop*)discovered_addr, current_head);
+    } else {
+      _bs->write_ref_field_pre((oop*)discovered_addr, current_head);
+    }
+    guarantee(false, "Need to check non-G1 collector");
   }
   oop retest = oopDesc::atomic_compare_exchange_oop(current_head, discovered_addr,
                                                     NULL);
@@ -1029,9 +1036,8 @@
     refs_list.set_head(obj);
     refs_list.inc_length(1);
     if (_discovered_list_needs_barrier) {
-      _bs->write_ref_field((void*)discovered_addr, current_head); guarantee(false, "Needs to be fixed: YSR");
+      _bs->write_ref_field((void*)discovered_addr, current_head);
     }
-
   } else {
     // If retest was non NULL, another thread beat us to it:
     // The reference has already been discovered...
@@ -1177,11 +1183,16 @@
     // pre-value, we can safely elide the pre-barrier here for the case of G1.
     assert(discovered == NULL, "control point invariant");
     if (_discovered_list_needs_barrier && !UseG1GC) { // safe to elide for G1
-      _bs->write_ref_field_pre((oop*)discovered_addr, current_head);
+      if (UseCompressedOops) {
+        _bs->write_ref_field_pre((narrowOop*)discovered_addr, current_head);
+      } else {
+        _bs->write_ref_field_pre((oop*)discovered_addr, current_head);
+      }
+      guarantee(false, "Need to check non-G1 collector");
     }
     oop_store_raw(discovered_addr, current_head);
     if (_discovered_list_needs_barrier) {
-      _bs->write_ref_field((oop*)discovered_addr, current_head);
+      _bs->write_ref_field((void*)discovered_addr, current_head);
     }
     list->set_head(obj);
     list->inc_length(1);