*** old/src/cpu/x86/vm/c1_LIRAssembler_x86.cpp	Tue Dec  7 17:33:22 2010
--- new/src/cpu/x86/vm/c1_LIRAssembler_x86.cpp	Tue Dec  7 17:33:21 2010

*** 1991,2009 ****
--- 1991,2008 ----
      assert(newval != addr, "new value and addr must be in different registers");
  
      if ( op->code() == lir_cas_obj) {
  #ifdef _LP64
        if (UseCompressedOops) {
          __ mov(rscratch1, cmpval);
          __ encode_heap_oop(cmpval);
!         __ mov(rscratch2, newval);
!         __ encode_heap_oop(rscratch2);
!         __ mov(rscratch1, newval);
!         __ encode_heap_oop(rscratch1);
          if (os::is_MP()) {
            __ lock();
          }
          __ cmpxchgl(rscratch2, Address(addr, 0));
!         __ mov(cmpval, rscratch1);
+         // cmpval (rax) is implicitly used by this instruction
!         __ cmpxchgl(rscratch1, Address(addr, 0));
        } else
  #endif
        {
          if (os::is_MP()) {
            __ lock();