--- old/src/hotspot/share/opto/macro.cpp	2018-03-07 15:00:28.908139222 +0100
+++ new/src/hotspot/share/opto/macro.cpp	2018-03-07 15:00:28.712134701 +0100
@@ -767,6 +767,9 @@
           DEBUG_ONLY(disq_node = use;)
         }
         can_eliminate = false;
+      } else {
+        assert(use->Opcode() == Op_CastP2X, "should be");
+        assert(!use->has_out_with(Op_OrL), "should have been removed because oop is never null");
       }
     }
   }