return UNCHANGED;
return DefUseEffect.UNCHANGED;
  private static byte longDiv(OPT_Instruction s) {   if (CF_LONG) {      OPT_Operand op1 = GuardedBinary.getVal1(s);      OPT_Operand op2 = GuardedBinary.getVal2(s);      if (op1.similar(op2)) {        // THE SAME OPERAND: x / x == 1        Move.mutate(s, LONG_MOVE, GuardedBinary.getClearResult(s),                     LC(1));        return MOVE_FOLDED;      }      if (op2.isLongConstant()) {        long val2 = op2.asLongConstant().value;        if (val2 == 0L) {          // TODO: This instruction is actually unreachable.            // There will be a LONG_ZERO_CHECK          // guarding this instruction that will result in an           // ArithmeticException.  We          // should probabbly just remove the LONG_DIV as dead code.          return UNCHANGED;        }        if (op1.isLongConstant()) {          // BOTH CONSTANTS: FOLD          long val1 = op1.asLongConstant().value;          Move.mutate(s, LONG_MOVE, GuardedBinary.getClearResult(s),                       LC(val1/val2));          return MOVE_FOLDED;        } else {          // ONLY OP2 IS CONSTANT: ATTEMPT TO APPLY AXIOMS          if (val2 == 1L) {                 // x / 1L == x            Move.mutate(s, LONG_MOVE, GuardedBinary.getClearResult(s),                         GuardedBinary.getClearVal1(s));            return MOVE_REDUCED;          }        }      }    }    return UNCHANGED;  }