--- a/hotspot/src/share/vm/c1/c1_Runtime1.cpp	Fri Jan 29 14:51:38 2010 -0800
+++ b/hotspot/src/share/vm/c1/c1_Runtime1.cpp	Mon Feb 01 17:29:01 2010 -0800
@@ -1075,6 +1075,7 @@
 };
 
 
+// Below length is the # elements copied.
 template <class T> int obj_arraycopy_work(oopDesc* src, T* src_addr,
                                           oopDesc* dst, T* dst_addr,
                                           int length) {
@@ -1083,22 +1084,22 @@
   // barrier. The assert will fail if this is not the case.
   // Note that we use the non-virtual inlineable variant of write_ref_array.
   BarrierSet* bs = Universe::heap()->barrier_set();
-  assert(bs->has_write_ref_array_opt(),
-         "Barrier set must have ref array opt");
+  assert(bs->has_write_ref_array_opt(), "Barrier set must have ref array opt");
+  assert(bs->has_write_ref_array_pre_opt(), "For pre-barrier as well.");
   if (src == dst) {
     // same object, no check
+    bs->write_ref_array_pre(dst_addr, length);
     Copy::conjoint_oops_atomic(src_addr, dst_addr, length);
-    bs->write_ref_array(MemRegion((HeapWord*)dst_addr,
-                                  (HeapWord*)(dst_addr + length)));
+    bs->write_ref_array((HeapWord*)dst_addr, length);
     return ac_ok;
   } else {
     klassOop bound = objArrayKlass::cast(dst->klass())->element_klass();
     klassOop stype = objArrayKlass::cast(src->klass())->element_klass();
     if (stype == bound || Klass::cast(stype)->is_subtype_of(bound)) {
       // Elements are guaranteed to be subtypes, so no check necessary
+      bs->write_ref_array_pre(dst_addr, length);
       Copy::conjoint_oops_atomic(src_addr, dst_addr, length);
-      bs->write_ref_array(MemRegion((HeapWord*)dst_addr,
-                                    (HeapWord*)(dst_addr + length)));
+      bs->write_ref_array((HeapWord*)dst_addr, length);
       return ac_ok;
     }
   }
@@ -1162,9 +1163,16 @@
 #endif
 
   if (num == 0) return;
+  BarrierSet* bs = Universe::heap()->barrier_set();
+  assert(bs->has_write_ref_array_opt(), "Barrier set must have ref array opt");
+  assert(bs->has_write_ref_array_pre_opt(), "For pre-barrier as well.");
+  if (UseCompressedOops) {
+    bs->write_ref_array_pre((narrowOop*)dst, num);
+  } else {
+    bs->write_ref_array_pre((oop*)dst, num);
+  }
   Copy::conjoint_oops_atomic((oop*) src, (oop*) dst, num);
-  BarrierSet* bs = Universe::heap()->barrier_set();
-  bs->write_ref_array(MemRegion(dst, dst + num));
+  bs->write_ref_array(dst, num);
 JRT_END