--- a/hotspot/src/cpu/x86/vm/x86.ad	Wed Sep 19 16:50:26 2012 -0700
+++ b/hotspot/src/cpu/x86/vm/x86.ad	Thu Sep 20 16:49:17 2012 +0200
@@ -503,6 +503,13 @@
       if ((UseSSE < 4) && (UseAVX < 1)) // only with SSE4_1 or AVX
         return false;
     break;
+    case Op_CompareAndSwapL:
+#ifdef _LP64
+    case Op_CompareAndSwapP:
+#endif
+      if (!VM_Version::supports_cx8())
+        return false;
+    break;
   }
 
   return true;  // Per default match rules are supported.