8264640: CMS ParScanClosure misses a barrier

Reviewed-by: yan, johnc

Author: AntonKozlov

src/hotspot/share/gc/cms/parOopClosures.inline.hpp

@@ -44,6 +44,7 @@ template <class T> inline void ParScanWeakRefClosure::do_oop_work(T* p) {
     // we need to ensure that it is copied (see comment in
     // ParScanClosure::do_oop_work).
     Klass* objK = obj->klass();
+    OrderAccess::loadload();
     markOop m = obj->mark_raw();
     oop new_obj;
     if (m->is_marked()) { // Contains forwarding pointer.
@@ -108,6 +109,7 @@ inline void ParScanClosure::do_oop_work(T* p,
       // overwritten with an overflow next pointer after the object is
       // forwarded.
       Klass* objK = obj->klass();
+      OrderAccess::loadload();
       markOop m = obj->mark_raw();
       oop new_obj;
       if (m->is_marked()) { // Contains forwarding pointer.