--- old/src/share/vm/utilities/copy.cpp	Wed Jun  9 10:46:11 2010
+++ new/src/share/vm/utilities/copy.cpp	Wed Jun  9 10:46:11 2010
@@ -28,6 +28,7 @@
 
 // Copy bytes; larger units are filled atomically if everything is aligned.
 void Copy::conjoint_memory_atomic(void* from, void* to, size_t size) {
+  if (size == 0) return;
   address src = (address) from;
   address dst = (address) to;
   uintptr_t bits = (uintptr_t) src | (uintptr_t) dst | (uintptr_t) size;
@@ -55,6 +56,7 @@
 
 // Fill bytes; larger units are filled atomically if everything is aligned.
 void Copy::fill_to_memory_atomic(void* to, size_t size, jubyte value) {
+  if (size == 0) return;
   address dst = (address) to;
   uintptr_t bits = (uintptr_t) to | (uintptr_t) size;
   if (bits % sizeof(jlong) == 0) {