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[DA] Let getConstantPart return optional APInt (NFC) #146135

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merged 2 commits into from
Jun 28, 2025
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[DA] Let getConstantPart return optional APInt (NFC) #146135

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[DA] Let getConstantPart return optional APInt (NFC)
artagnon Jun 27, 2025
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artagnon Jun 27, 2025
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58 changes: 25 additions & 33 deletions llvm/lib/Analysis/DependenceAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2372,20 +2372,17 @@ bool DependenceInfo::testMIV(const SCEV *Src, const SCEV *Dst,
banerjeeMIVtest(Src, Dst, Loops, Result);
}


// Given a product, e.g., 10*X*Y, returns the first constant operand,
// in this case 10. If there is no constant part, returns NULL.
static
const SCEVConstant *getConstantPart(const SCEV *Expr) {
// in this case 10. If there is no constant part, returns std::nullopt.
static std::optional<APInt> getConstantPart(const SCEV *Expr) {
if (const auto *Constant = dyn_cast<SCEVConstant>(Expr))
return Constant;
else if (const auto *Product = dyn_cast<SCEVMulExpr>(Expr))
return Constant->getAPInt();
if (const auto *Product = dyn_cast<SCEVMulExpr>(Expr))
if (const auto *Constant = dyn_cast<SCEVConstant>(Product->getOperand(0)))
return Constant;
return nullptr;
return Constant->getAPInt();
return std::nullopt;
}


//===----------------------------------------------------------------------===//
// gcdMIVtest -
// Tests an MIV subscript pair for dependence.
Expand Down Expand Up @@ -2421,11 +2418,10 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
const SCEV *Coeff = AddRec->getStepRecurrence(*SE);
// If the coefficient is the product of a constant and other stuff,
// we can use the constant in the GCD computation.
const auto *Constant = getConstantPart(Coeff);
if (!Constant)
std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
if (!ConstCoeff)
return false;
APInt ConstCoeff = Constant->getAPInt();
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
Coefficients = AddRec->getStart();
}
const SCEV *SrcConst = Coefficients;
Expand All @@ -2440,11 +2436,10 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
const SCEV *Coeff = AddRec->getStepRecurrence(*SE);
// If the coefficient is the product of a constant and other stuff,
// we can use the constant in the GCD computation.
const auto *Constant = getConstantPart(Coeff);
if (!Constant)
std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
if (!ConstCoeff)
return false;
APInt ConstCoeff = Constant->getAPInt();
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
Coefficients = AddRec->getStart();
}
const SCEV *DstConst = Coefficients;
Expand All @@ -2463,12 +2458,10 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
else if (const SCEVMulExpr *Product = dyn_cast<SCEVMulExpr>(Operand)) {
// Search for constant operand to participate in GCD;
// If none found; return false.
const SCEVConstant *ConstOp = getConstantPart(Product);
std::optional<APInt> ConstOp = getConstantPart(Product);
if (!ConstOp)
return false;
APInt ConstOpValue = ConstOp->getAPInt();
ExtraGCD = APIntOps::GreatestCommonDivisor(ExtraGCD,
ConstOpValue.abs());
ExtraGCD = APIntOps::GreatestCommonDivisor(ExtraGCD, ConstOp->abs());
}
else
return false;
Expand Down Expand Up @@ -2520,11 +2513,11 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
else {
// If the coefficient is the product of a constant and other stuff,
// we can use the constant in the GCD computation.
Constant = getConstantPart(Coeff);
if (!Constant)
std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
if (!ConstCoeff)
return false;
APInt ConstCoeff = Constant->getAPInt();
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
RunningGCD =
APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
}
Inner = AddRec->getStart();
}
Expand All @@ -2537,24 +2530,23 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
else {
// If the coefficient is the product of a constant and other stuff,
// we can use the constant in the GCD computation.
Constant = getConstantPart(Coeff);
if (!Constant)
std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
if (!ConstCoeff)
return false;
APInt ConstCoeff = Constant->getAPInt();
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
RunningGCD =
APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
}
Inner = AddRec->getStart();
}
Delta = SE->getMinusSCEV(SrcCoeff, DstCoeff);
// If the coefficient is the product of a constant and other stuff,
// we can use the constant in the GCD computation.
Constant = getConstantPart(Delta);
if (!Constant)
std::optional<APInt> ConstCoeff = getConstantPart(Delta);
if (!ConstCoeff)
// The difference of the two coefficients might not be a product
// or constant, in which case we give up on this direction.
continue;
APInt ConstCoeff = Constant->getAPInt();
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
LLVM_DEBUG(dbgs() << "\tRunningGCD = " << RunningGCD << "\n");
if (RunningGCD != 0) {
Remainder = ConstDelta.srem(RunningGCD);
Expand Down
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