// If we know the shifter operand is nonzero, we can sometimes infer more
// known bits. However this is expensive to compute, so be lazy about it and
// only compute it when absolutely necessary.
- Optional<bool> ShifterOperandIsNonZero;
-
// Early exit if we can't constrain any well-defined shift amount.
if (!(ShiftAmtKZ & (PowerOf2Ceil(BitWidth) - 1)) &&
!(ShiftAmtKO & (PowerOf2Ceil(BitWidth) - 1))) {
- ShifterOperandIsNonZero =
- isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q);
- if (!*ShifterOperandIsNonZero)
- return;
+ return;
}
Known.Zero.setAllBits();
continue;
if ((ShiftAmt | ShiftAmtKO) != ShiftAmt)
continue;
- // If we know the shifter is nonzero, we may be able to infer more known
- // bits. This check is sunk down as far as possible to avoid the expensive
- // call to isKnownNonZero if the cheaper checks above fail.
- if (ShiftAmt == 0) {
- if (!ShifterOperandIsNonZero.hasValue())
- ShifterOperandIsNonZero =
- isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q);
- if (*ShifterOperandIsNonZero)
- continue;
- }
-
Known = KnownBits::commonBits(
Known, KF(Known2, KnownBits::makeConstant(APInt(32, ShiftAmt))));
}