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[X86] Sink NOT to be fold into ANDN #172329

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[X86] Sink NOT to be fold into ANDN #172329

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532f68e
[X86][test] Add tests for sinking NOT to be fold into ANDN
pfusik Dec 15, 2025
5139a90
[X86] Sink NOT to be fold into ANDN
pfusik Dec 15, 2025
91550c6
[X86] Use BMI for vectors, if vector instructions absent
pfusik Dec 17, 2025
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22 changes: 22 additions & 0 deletions llvm/lib/Target/X86/X86TargetTransformInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7198,6 +7198,28 @@ bool X86TTIImpl::isProfitableToSinkOperands(Instruction *I,
SmallVectorImpl<Use *> &Ops) const {
using namespace llvm::PatternMatch;

if (I->getOpcode() == Instruction::And &&
(ST->hasBMI() || (I->getType()->isVectorTy() && ST->hasSSE2()))) {
for (auto &Op : I->operands()) {
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@RKSimon RKSimon Dec 17, 2025

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Can't pattern match do the commutative matching m_c_And()?

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@pfusik pfusik Dec 17, 2025

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m_c_And() doesn't tell us which of the two operands is a not and we need to return the Use of not in Ops.

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@RKSimon RKSimon Dec 17, 2025

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Feasible to add a PatternMatch::m_Use(Use *&U) matcher?

// (and X, (not Y)) -> (andn X, Y)
if (match(Op.get(), m_Not(m_Value()))) {
Ops.push_back(&Op);
return true;
}
// (and X, (splat (not Y))) -> (andn X, (splat Y))
if (match(Op.get(),
m_Shuffle(m_InsertElt(m_Value(), m_Not(m_Value()), m_ZeroInt()),
m_Value(), m_ZeroMask()))) {
Use &InsertElt = cast<Instruction>(Op)->getOperandUse(0);
Use &Not = cast<Instruction>(InsertElt)->getOperandUse(1);
Ops.push_back(&Not);
Ops.push_back(&InsertElt);
Ops.push_back(&Op);
return true;
}
}
}

FixedVectorType *VTy = dyn_cast<FixedVectorType>(I->getType());
if (!VTy)
return false;
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