--- a/src/share/vm/memory/genOopClosures.inline.hpp	Fri Apr 11 09:56:35 2008 -0400
+++ b/src/share/vm/memory/genOopClosures.inline.hpp	Sun Apr 13 17:43:42 2008 -0400
@@ -38,10 +38,10 @@
   }
 }
 
-inline void OopsInGenClosure::do_barrier(oop* p) {
+template <class T> inline void OopsInGenClosure::do_barrier(T* p) {
   assert(generation()->is_in_reserved(p), "expected ref in generation");
-  oop obj = *p;
-  assert(obj != NULL, "expected non-null object");
+  assert(!oopDesc::is_null(*p), "expected non-null object");
+  oop obj = oopDesc::load_decode_heap_oop_not_null(p);
   // If p points to a younger generation, mark the card.
   if ((HeapWord*)obj < _gen_boundary) {
     _rs->inline_write_ref_field_gc(p, obj);
@@ -49,18 +49,17 @@
 }
 
 // NOTE! Any changes made here should also be made
-// in FastScanClosure::do_oop();
-inline void ScanClosure::do_oop(oop* p) {
-  oop obj = *p;
+// in FastScanClosure::do_oop_work()
+template <class T> inline void ScanClosure::do_oop_work(T* p) {
+  T heap_oop = oopDesc::load_heap_oop(p);
   // Should we copy the obj?
-  if (obj != NULL) {
+  if (!oopDesc::is_null(heap_oop)) {
+    oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
     if ((HeapWord*)obj < _boundary) {
       assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?");
-      if (obj->is_forwarded()) {
-        *p = obj->forwardee();
-      } else {
-        *p = _g->copy_to_survivor_space(obj, p);
-      }
+      oop new_obj = obj->is_forwarded() ? obj->forwardee()
+                                        : _g->copy_to_survivor_space(obj);
+      oopDesc::encode_store_heap_oop_not_null(p, new_obj);
     }
     if (_gc_barrier) {
       // Now call parent closure
@@ -69,23 +68,21 @@
   }
 }
 
-inline void ScanClosure::do_oop_nv(oop* p) {
-  ScanClosure::do_oop(p);
-}
+inline void ScanClosure::do_oop_nv(oop* p)       { ScanClosure::do_oop_work(p); }
+inline void ScanClosure::do_oop_nv(narrowOop* p) { ScanClosure::do_oop_work(p); }
 
 // NOTE! Any changes made here should also be made
-// in ScanClosure::do_oop();
-inline void FastScanClosure::do_oop(oop* p) {
-  oop obj = *p;
+// in ScanClosure::do_oop_work()
+template <class T> inline void FastScanClosure::do_oop_work(T* p) {
+  T heap_oop = oopDesc::load_heap_oop(p);
   // Should we copy the obj?
-  if (obj != NULL) {
+  if (!oopDesc::is_null(heap_oop)) {
+    oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
     if ((HeapWord*)obj < _boundary) {
       assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?");
-      if (obj->is_forwarded()) {
-        *p = obj->forwardee();
-      } else {
-        *p = _g->copy_to_survivor_space(obj, p);
-      }
+      oop new_obj = obj->is_forwarded() ? obj->forwardee()
+                                        : _g->copy_to_survivor_space(obj);
+      oopDesc::encode_store_heap_oop_not_null(p, new_obj);
       if (_gc_barrier) {
         // Now call parent closure
         do_barrier(p);
@@ -94,26 +91,22 @@
   }
 }
 
-inline void FastScanClosure::do_oop_nv(oop* p) {
-  FastScanClosure::do_oop(p);
-}
+inline void FastScanClosure::do_oop_nv(oop* p)       { FastScanClosure::do_oop_work(p); }
+inline void FastScanClosure::do_oop_nv(narrowOop* p) { FastScanClosure::do_oop_work(p); }
 
 // Note similarity to ScanClosure; the difference is that
 // the barrier set is taken care of outside this closure.
-inline void ScanWeakRefClosure::do_oop(oop* p) {
-  oop obj = *p;
-  assert (obj != NULL, "null weak reference?");
+template <class T> inline void ScanWeakRefClosure::do_oop_work(T* p) {
+  assert(!oopDesc::is_null(*p), "null weak reference?");
+  oop obj = oopDesc::load_decode_heap_oop_not_null(p);
   // weak references are sometimes scanned twice; must check
   // that to-space doesn't already contain this object
   if ((HeapWord*)obj < _boundary && !_g->to()->is_in_reserved(obj)) {
-    if (obj->is_forwarded()) {
-      *p = obj->forwardee();
-    } else {
-      *p = _g->copy_to_survivor_space(obj, p);
-    }
+    oop new_obj = obj->is_forwarded() ? obj->forwardee()
+                                      : _g->copy_to_survivor_space(obj);
+    oopDesc::encode_store_heap_oop_not_null(p, new_obj);
   }
 }
 
-inline void ScanWeakRefClosure::do_oop_nv(oop* p) {
-  ScanWeakRefClosure::do_oop(p);
-}
+inline void ScanWeakRefClosure::do_oop_nv(oop* p)       { ScanWeakRefClosure::do_oop_work(p); }
+inline void ScanWeakRefClosure::do_oop_nv(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); }