return UNCHANGED;
return DefUseEffect.UNCHANGED;
  private static byte instanceOfNotNull(OPT_Instruction s) {   {      OPT_Operand ref = InstanceOf.getRef(s);      VM_TypeReference lhsType = InstanceOf.getType(s).getTypeRef();      VM_TypeReference rhsType = ref.getType();      byte ans = OPT_ClassLoaderProxy.includesType(lhsType, rhsType);      if (ans == OPT_Constants.YES) {        Move.mutate(s, INT_MOVE, InstanceOf.getClearResult(s), IC(1));        return MOVE_FOLDED;      } else if (ans == OPT_Constants.NO) {        VM_Type rType = rhsType.peekResolvedType();        if (rType != null && rType.isClassType() && rType.asClass().isFinal()) {          // only final (or precise) rhs types can be optimized since rhsType may be conservative          Move.mutate(s, INT_MOVE, InstanceOf.getClearResult(s), IC(0));          return MOVE_FOLDED;        }      }    }    return UNCHANGED;  }