return UNCHANGED;
return DefUseEffect.UNCHANGED;
  private static byte longZeroCheck(OPT_Instruction s) {   {      OPT_Operand op = ZeroCheck.getValue(s);      if (op.isLongConstant()) {        long val = op.asLongConstant().value;        if (val == 0L) {          Trap.mutate(s, TRAP, ZeroCheck.getClearGuardResult(s),                      OPT_TrapCodeOperand.DivByZero());          return TRAP_REDUCED;        } else {          Move.mutate(s, GUARD_MOVE, ZeroCheck.getClearGuardResult(s), TG());          return MOVE_FOLDED;        }      }    }    return UNCHANGED;  }