diff -r dfe27f03244a -r e9ff18c4ace7 src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Tue Jun 01 11:48:33 2010 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Wed Jun 02 22:45:42 2010 -0700
@@ -1414,6 +1414,8 @@
 {
   assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
          "must move left or to a different space");
+  assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr),
+         "checking alignment");
 }
 #endif // ASSERT