diff -r bb18957ad21e -r df6caf649ff7 src/share/vm/memory/barrierSet.cpp
--- a/src/share/vm/memory/barrierSet.cpp	Fri Jul 10 16:01:20 2009 -0700
+++ b/src/share/vm/memory/barrierSet.cpp	Tue Jul 14 15:40:39 2009 -0700
@@ -25,12 +25,27 @@
 # include "incls/_precompiled.incl"
 # include "incls/_barrierSet.cpp.incl"
 
-// count is in HeapWord's
+// count is number of array elements being written
 void BarrierSet::static_write_ref_array_pre(HeapWord* start, size_t count) {
-   Universe::heap()->barrier_set()->write_ref_array_pre(MemRegion(start, start + count));
+  assert(count <= (size_t)max_intx, "count too large");
+#if 0
+  warning("Pre: \t" INTPTR_FORMAT "[" SIZE_FORMAT "]\t",
+                   start,            count);
+#endif
+  if (UseCompressedOops) {
+    Universe::heap()->barrier_set()->write_ref_array_pre((narrowOop*)start, (int)count);
+  } else {
+    Universe::heap()->barrier_set()->write_ref_array_pre(      (oop*)start, (int)count);
+  }
 }
 
-// count is in HeapWord's
+// count is number of array elements being written
 void BarrierSet::static_write_ref_array_post(HeapWord* start, size_t count) {
-   Universe::heap()->barrier_set()->write_ref_array_work(MemRegion(start, start + count));
+  assert(count <= (size_t)max_intx, "count too large");
+  HeapWord* end = start + objArrayOopDesc::array_size((int)count);
+#if 0
+  warning("Post:\t" INTPTR_FORMAT "[" SIZE_FORMAT "] : [" INTPTR_FORMAT","INTPTR_FORMAT")\t",
+                   start,            count,              start,          end);
+#endif
+  Universe::heap()->barrier_set()->write_ref_array_work(MemRegion(start, end));
 }