--- old/src/hotspot/share/opto/macro.cpp	2018-02-22 16:36:24.944513113 +0100
+++ new/src/hotspot/share/opto/macro.cpp	2018-02-22 16:36:24.748514383 +0100
@@ -767,6 +767,13 @@
           DEBUG_ONLY(disq_node = use;)
         }
         can_eliminate = false;
+      } else {
+        assert(use->Opcode() == Op_CastP2X, "should be");
+        if (use->has_out_with(Op_OrL)) {
+          // Fixme
+          // This is not a card mark!
+          can_eliminate = false;
+        }
       }
     }
   }