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[DAG] computeKnownBits - Replace ISD::SREM handling with KnownBits::srem to reduce code duplication

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This commit is contained in:
Simon Pilgrim 2020-11-05 15:44:38 +00:00
parent ba9ef76ad5
commit 6d3173c2b6
1 changed files with 5 additions and 23 deletions
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28
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -3249,30 +3249,12 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
Known = KnownBits::computeForAddCarry(Known, Known2, Carry); Known = KnownBits::computeForAddCarry(Known, Known2, Carry);
break; break;
} }
case ISD::SREM: case ISD::SREM: {
if (ConstantSDNode *Rem = isConstOrConstSplat(Op.getOperand(1))) { Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
const APInt &RA = Rem->getAPIntValue().abs(); Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
if (RA.isPowerOf2()) { Known = KnownBits::srem(Known, Known2);
APInt LowBits = RA - 1;
Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
// The low bits of the first operand are unchanged by the srem.
Known.Zero = Known2.Zero & LowBits;
Known.One = Known2.One & LowBits;
// If the first operand is non-negative or has all low bits zero, then
// the upper bits are all zero.
if (Known2.isNonNegative() || LowBits.isSubsetOf(Known2.Zero))
Known.Zero |= ~LowBits;
// If the first operand is negative and not all low bits are zero, then
// the upper bits are all one.
if (Known2.isNegative() && LowBits.intersects(Known2.One))
Known.One |= ~LowBits;
assert((Known.Zero & Known.One) == 0&&"Bits known to be one AND zero?");
}
}
break; break;
}
case ISD::UREM: { case ISD::UREM: {
Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1); Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1); Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);