return UNCHANGED;
return DefUseEffect.UNCHANGED;
  private static byte instanceOf(OPT_AbstractRegisterPool regpool, OPT_Instruction s) {    OPT_Operand ref = InstanceOf.getRef(s);    if (ref.isNullConstant()) {      Move.mutate(s, INT_MOVE, InstanceOf.getClearResult(s), IC(0));      return MOVE_FOLDED;    } else if (ref.isConstant()) {      s.operator = INSTANCEOF_NOTNULL;      return instanceOfNotNull(s);    } else {      VM_TypeReference lhsType = InstanceOf.getType(s).getTypeRef();      VM_TypeReference rhsType = ref.getType();      byte ans = OPT_ClassLoaderProxy.includesType(lhsType, rhsType);      // NOTE: OPT_Constants.YES doesn't help because ref may be null and null instanceof T is false      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;        }        else {          return UNCHANGED;        }      }      else {        return UNCHANGED;      }    }  }