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[InstCombine] Split the FMul with reassoc into a helper function, NFC #71493

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merged 1 commit into from
Nov 7, 2023
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[InstCombine] Split the FMul with reassoc into a helper function, NFC #71493

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1 change: 1 addition & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineInternal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,7 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
Instruction *visitSub(BinaryOperator &I);
Instruction *visitFSub(BinaryOperator &I);
Instruction *visitMul(BinaryOperator &I);
Instruction *foldFMulReassoc(BinaryOperator &I);
Instruction *visitFMul(BinaryOperator &I);
Instruction *visitURem(BinaryOperator &I);
Instruction *visitSRem(BinaryOperator &I);
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347 changes: 177 additions & 170 deletions llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,180 @@ Instruction *InstCombinerImpl::foldFPSignBitOps(BinaryOperator &I) {
return nullptr;
}

Instruction *InstCombinerImpl::foldFMulReassoc(BinaryOperator &I) {
Value *Op0 = I.getOperand(0);
Value *Op1 = I.getOperand(1);
Value *X, *Y;
Constant *C;

// Reassociate constant RHS with another constant to form constant
// expression.
if (match(Op1, m_Constant(C)) && C->isFiniteNonZeroFP()) {
Constant *C1;
if (match(Op0, m_OneUse(m_FDiv(m_Constant(C1), m_Value(X))))) {
// (C1 / X) * C --> (C * C1) / X
Constant *CC1 =
ConstantFoldBinaryOpOperands(Instruction::FMul, C, C1, DL);
if (CC1 && CC1->isNormalFP())
return BinaryOperator::CreateFDivFMF(CC1, X, &I);
}
if (match(Op0, m_FDiv(m_Value(X), m_Constant(C1)))) {
// (X / C1) * C --> X * (C / C1)
Constant *CDivC1 =
ConstantFoldBinaryOpOperands(Instruction::FDiv, C, C1, DL);
if (CDivC1 && CDivC1->isNormalFP())
return BinaryOperator::CreateFMulFMF(X, CDivC1, &I);

// If the constant was a denormal, try reassociating differently.
// (X / C1) * C --> X / (C1 / C)
Constant *C1DivC =
ConstantFoldBinaryOpOperands(Instruction::FDiv, C1, C, DL);
if (C1DivC && Op0->hasOneUse() && C1DivC->isNormalFP())
return BinaryOperator::CreateFDivFMF(X, C1DivC, &I);
}

// We do not need to match 'fadd C, X' and 'fsub X, C' because they are
// canonicalized to 'fadd X, C'. Distributing the multiply may allow
// further folds and (X * C) + C2 is 'fma'.
if (match(Op0, m_OneUse(m_FAdd(m_Value(X), m_Constant(C1))))) {
// (X + C1) * C --> (X * C) + (C * C1)
if (Constant *CC1 =
ConstantFoldBinaryOpOperands(Instruction::FMul, C, C1, DL)) {
Value *XC = Builder.CreateFMulFMF(X, C, &I);
return BinaryOperator::CreateFAddFMF(XC, CC1, &I);
}
}
if (match(Op0, m_OneUse(m_FSub(m_Constant(C1), m_Value(X))))) {
// (C1 - X) * C --> (C * C1) - (X * C)
if (Constant *CC1 =
ConstantFoldBinaryOpOperands(Instruction::FMul, C, C1, DL)) {
Value *XC = Builder.CreateFMulFMF(X, C, &I);
return BinaryOperator::CreateFSubFMF(CC1, XC, &I);
}
}
}

Value *Z;
if (match(&I,
m_c_FMul(m_OneUse(m_FDiv(m_Value(X), m_Value(Y))), m_Value(Z)))) {
// Sink division: (X / Y) * Z --> (X * Z) / Y
Value *NewFMul = Builder.CreateFMulFMF(X, Z, &I);
return BinaryOperator::CreateFDivFMF(NewFMul, Y, &I);
}

// sqrt(X) * sqrt(Y) -> sqrt(X * Y)
// nnan disallows the possibility of returning a number if both operands are
// negative (in that case, we should return NaN).
if (I.hasNoNaNs() && match(Op0, m_OneUse(m_Sqrt(m_Value(X)))) &&
match(Op1, m_OneUse(m_Sqrt(m_Value(Y))))) {
Value *XY = Builder.CreateFMulFMF(X, Y, &I);
Value *Sqrt = Builder.CreateUnaryIntrinsic(Intrinsic::sqrt, XY, &I);
return replaceInstUsesWith(I, Sqrt);
}

// The following transforms are done irrespective of the number of uses
// for the expression "1.0/sqrt(X)".
// 1) 1.0/sqrt(X) * X -> X/sqrt(X)
// 2) X * 1.0/sqrt(X) -> X/sqrt(X)
// We always expect the backend to reduce X/sqrt(X) to sqrt(X), if it
// has the necessary (reassoc) fast-math-flags.
if (I.hasNoSignedZeros() &&
match(Op0, (m_FDiv(m_SpecificFP(1.0), m_Value(Y)))) &&
match(Y, m_Sqrt(m_Value(X))) && Op1 == X)
return BinaryOperator::CreateFDivFMF(X, Y, &I);
if (I.hasNoSignedZeros() &&
match(Op1, (m_FDiv(m_SpecificFP(1.0), m_Value(Y)))) &&
match(Y, m_Sqrt(m_Value(X))) && Op0 == X)
return BinaryOperator::CreateFDivFMF(X, Y, &I);

// Like the similar transform in instsimplify, this requires 'nsz' because
// sqrt(-0.0) = -0.0, and -0.0 * -0.0 does not simplify to -0.0.
if (I.hasNoNaNs() && I.hasNoSignedZeros() && Op0 == Op1 && Op0->hasNUses(2)) {
// Peek through fdiv to find squaring of square root:
// (X / sqrt(Y)) * (X / sqrt(Y)) --> (X * X) / Y
if (match(Op0, m_FDiv(m_Value(X), m_Sqrt(m_Value(Y))))) {
Value *XX = Builder.CreateFMulFMF(X, X, &I);
return BinaryOperator::CreateFDivFMF(XX, Y, &I);
}
// (sqrt(Y) / X) * (sqrt(Y) / X) --> Y / (X * X)
if (match(Op0, m_FDiv(m_Sqrt(m_Value(Y)), m_Value(X)))) {
Value *XX = Builder.CreateFMulFMF(X, X, &I);
return BinaryOperator::CreateFDivFMF(Y, XX, &I);
}
}

// pow(X, Y) * X --> pow(X, Y+1)
// X * pow(X, Y) --> pow(X, Y+1)
if (match(&I, m_c_FMul(m_OneUse(m_Intrinsic<Intrinsic::pow>(m_Value(X),
m_Value(Y))),
m_Deferred(X)))) {
Value *Y1 = Builder.CreateFAddFMF(Y, ConstantFP::get(I.getType(), 1.0), &I);
Value *Pow = Builder.CreateBinaryIntrinsic(Intrinsic::pow, X, Y1, &I);
return replaceInstUsesWith(I, Pow);
}

if (I.isOnlyUserOfAnyOperand()) {
// pow(X, Y) * pow(X, Z) -> pow(X, Y + Z)
if (match(Op0, m_Intrinsic<Intrinsic::pow>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::pow>(m_Specific(X), m_Value(Z)))) {
auto *YZ = Builder.CreateFAddFMF(Y, Z, &I);
auto *NewPow = Builder.CreateBinaryIntrinsic(Intrinsic::pow, X, YZ, &I);
return replaceInstUsesWith(I, NewPow);
}
// pow(X, Y) * pow(Z, Y) -> pow(X * Z, Y)
if (match(Op0, m_Intrinsic<Intrinsic::pow>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::pow>(m_Value(Z), m_Specific(Y)))) {
auto *XZ = Builder.CreateFMulFMF(X, Z, &I);
auto *NewPow = Builder.CreateBinaryIntrinsic(Intrinsic::pow, XZ, Y, &I);
return replaceInstUsesWith(I, NewPow);
}

// powi(x, y) * powi(x, z) -> powi(x, y + z)
if (match(Op0, m_Intrinsic<Intrinsic::powi>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::powi>(m_Specific(X), m_Value(Z))) &&
Y->getType() == Z->getType()) {
auto *YZ = Builder.CreateAdd(Y, Z);
auto *NewPow = Builder.CreateIntrinsic(
Intrinsic::powi, {X->getType(), YZ->getType()}, {X, YZ}, &I);
return replaceInstUsesWith(I, NewPow);
}

// exp(X) * exp(Y) -> exp(X + Y)
if (match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X))) &&
match(Op1, m_Intrinsic<Intrinsic::exp>(m_Value(Y)))) {
Value *XY = Builder.CreateFAddFMF(X, Y, &I);
Value *Exp = Builder.CreateUnaryIntrinsic(Intrinsic::exp, XY, &I);
return replaceInstUsesWith(I, Exp);
}

// exp2(X) * exp2(Y) -> exp2(X + Y)
if (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) &&
match(Op1, m_Intrinsic<Intrinsic::exp2>(m_Value(Y)))) {
Value *XY = Builder.CreateFAddFMF(X, Y, &I);
Value *Exp2 = Builder.CreateUnaryIntrinsic(Intrinsic::exp2, XY, &I);
return replaceInstUsesWith(I, Exp2);
}
}

// (X*Y) * X => (X*X) * Y where Y != X
// The purpose is two-fold:
// 1) to form a power expression (of X).
// 2) potentially shorten the critical path: After transformation, the
// latency of the instruction Y is amortized by the expression of X*X,
// and therefore Y is in a "less critical" position compared to what it
// was before the transformation.
if (match(Op0, m_OneUse(m_c_FMul(m_Specific(Op1), m_Value(Y)))) && Op1 != Y) {
Value *XX = Builder.CreateFMulFMF(Op1, Op1, &I);
return BinaryOperator::CreateFMulFMF(XX, Y, &I);
}
if (match(Op1, m_OneUse(m_c_FMul(m_Specific(Op0), m_Value(Y)))) && Op0 != Y) {
Value *XX = Builder.CreateFMulFMF(Op0, Op0, &I);
return BinaryOperator::CreateFMulFMF(XX, Y, &I);
}

return nullptr;
}

Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
if (Value *V = simplifyFMulInst(I.getOperand(0), I.getOperand(1),
I.getFastMathFlags(),
Expand Down Expand Up @@ -607,176 +781,9 @@ Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
if (Value *V = SimplifySelectsFeedingBinaryOp(I, Op0, Op1))
return replaceInstUsesWith(I, V);

if (I.hasAllowReassoc()) {
// Reassociate constant RHS with another constant to form constant
// expression.
if (match(Op1, m_Constant(C)) && C->isFiniteNonZeroFP()) {
Constant *C1;
if (match(Op0, m_OneUse(m_FDiv(m_Constant(C1), m_Value(X))))) {
// (C1 / X) * C --> (C * C1) / X
Constant *CC1 =
ConstantFoldBinaryOpOperands(Instruction::FMul, C, C1, DL);
if (CC1 && CC1->isNormalFP())
return BinaryOperator::CreateFDivFMF(CC1, X, &I);
}
if (match(Op0, m_FDiv(m_Value(X), m_Constant(C1)))) {
// (X / C1) * C --> X * (C / C1)
Constant *CDivC1 =
ConstantFoldBinaryOpOperands(Instruction::FDiv, C, C1, DL);
if (CDivC1 && CDivC1->isNormalFP())
return BinaryOperator::CreateFMulFMF(X, CDivC1, &I);

// If the constant was a denormal, try reassociating differently.
// (X / C1) * C --> X / (C1 / C)
Constant *C1DivC =
ConstantFoldBinaryOpOperands(Instruction::FDiv, C1, C, DL);
if (C1DivC && Op0->hasOneUse() && C1DivC->isNormalFP())
return BinaryOperator::CreateFDivFMF(X, C1DivC, &I);
}

// We do not need to match 'fadd C, X' and 'fsub X, C' because they are
// canonicalized to 'fadd X, C'. Distributing the multiply may allow
// further folds and (X * C) + C2 is 'fma'.
if (match(Op0, m_OneUse(m_FAdd(m_Value(X), m_Constant(C1))))) {
// (X + C1) * C --> (X * C) + (C * C1)
if (Constant *CC1 = ConstantFoldBinaryOpOperands(
Instruction::FMul, C, C1, DL)) {
Value *XC = Builder.CreateFMulFMF(X, C, &I);
return BinaryOperator::CreateFAddFMF(XC, CC1, &I);
}
}
if (match(Op0, m_OneUse(m_FSub(m_Constant(C1), m_Value(X))))) {
// (C1 - X) * C --> (C * C1) - (X * C)
if (Constant *CC1 = ConstantFoldBinaryOpOperands(
Instruction::FMul, C, C1, DL)) {
Value *XC = Builder.CreateFMulFMF(X, C, &I);
return BinaryOperator::CreateFSubFMF(CC1, XC, &I);
}
}
}

Value *Z;
if (match(&I, m_c_FMul(m_OneUse(m_FDiv(m_Value(X), m_Value(Y))),
m_Value(Z)))) {
// Sink division: (X / Y) * Z --> (X * Z) / Y
Value *NewFMul = Builder.CreateFMulFMF(X, Z, &I);
return BinaryOperator::CreateFDivFMF(NewFMul, Y, &I);
}

// sqrt(X) * sqrt(Y) -> sqrt(X * Y)
// nnan disallows the possibility of returning a number if both operands are
// negative (in that case, we should return NaN).
if (I.hasNoNaNs() && match(Op0, m_OneUse(m_Sqrt(m_Value(X)))) &&
match(Op1, m_OneUse(m_Sqrt(m_Value(Y))))) {
Value *XY = Builder.CreateFMulFMF(X, Y, &I);
Value *Sqrt = Builder.CreateUnaryIntrinsic(Intrinsic::sqrt, XY, &I);
return replaceInstUsesWith(I, Sqrt);
}

// The following transforms are done irrespective of the number of uses
// for the expression "1.0/sqrt(X)".
// 1) 1.0/sqrt(X) * X -> X/sqrt(X)
// 2) X * 1.0/sqrt(X) -> X/sqrt(X)
// We always expect the backend to reduce X/sqrt(X) to sqrt(X), if it
// has the necessary (reassoc) fast-math-flags.
if (I.hasNoSignedZeros() &&
match(Op0, (m_FDiv(m_SpecificFP(1.0), m_Value(Y)))) &&
match(Y, m_Sqrt(m_Value(X))) && Op1 == X)
return BinaryOperator::CreateFDivFMF(X, Y, &I);
if (I.hasNoSignedZeros() &&
match(Op1, (m_FDiv(m_SpecificFP(1.0), m_Value(Y)))) &&
match(Y, m_Sqrt(m_Value(X))) && Op0 == X)
return BinaryOperator::CreateFDivFMF(X, Y, &I);

// Like the similar transform in instsimplify, this requires 'nsz' because
// sqrt(-0.0) = -0.0, and -0.0 * -0.0 does not simplify to -0.0.
if (I.hasNoNaNs() && I.hasNoSignedZeros() && Op0 == Op1 &&
Op0->hasNUses(2)) {
// Peek through fdiv to find squaring of square root:
// (X / sqrt(Y)) * (X / sqrt(Y)) --> (X * X) / Y
if (match(Op0, m_FDiv(m_Value(X), m_Sqrt(m_Value(Y))))) {
Value *XX = Builder.CreateFMulFMF(X, X, &I);
return BinaryOperator::CreateFDivFMF(XX, Y, &I);
}
// (sqrt(Y) / X) * (sqrt(Y) / X) --> Y / (X * X)
if (match(Op0, m_FDiv(m_Sqrt(m_Value(Y)), m_Value(X)))) {
Value *XX = Builder.CreateFMulFMF(X, X, &I);
return BinaryOperator::CreateFDivFMF(Y, XX, &I);
}
}

// pow(X, Y) * X --> pow(X, Y+1)
// X * pow(X, Y) --> pow(X, Y+1)
if (match(&I, m_c_FMul(m_OneUse(m_Intrinsic<Intrinsic::pow>(m_Value(X),
m_Value(Y))),
m_Deferred(X)))) {
Value *Y1 =
Builder.CreateFAddFMF(Y, ConstantFP::get(I.getType(), 1.0), &I);
Value *Pow = Builder.CreateBinaryIntrinsic(Intrinsic::pow, X, Y1, &I);
return replaceInstUsesWith(I, Pow);
}

if (I.isOnlyUserOfAnyOperand()) {
// pow(X, Y) * pow(X, Z) -> pow(X, Y + Z)
if (match(Op0, m_Intrinsic<Intrinsic::pow>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::pow>(m_Specific(X), m_Value(Z)))) {
auto *YZ = Builder.CreateFAddFMF(Y, Z, &I);
auto *NewPow = Builder.CreateBinaryIntrinsic(Intrinsic::pow, X, YZ, &I);
return replaceInstUsesWith(I, NewPow);
}
// pow(X, Y) * pow(Z, Y) -> pow(X * Z, Y)
if (match(Op0, m_Intrinsic<Intrinsic::pow>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::pow>(m_Value(Z), m_Specific(Y)))) {
auto *XZ = Builder.CreateFMulFMF(X, Z, &I);
auto *NewPow = Builder.CreateBinaryIntrinsic(Intrinsic::pow, XZ, Y, &I);
return replaceInstUsesWith(I, NewPow);
}

// powi(x, y) * powi(x, z) -> powi(x, y + z)
if (match(Op0, m_Intrinsic<Intrinsic::powi>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::powi>(m_Specific(X), m_Value(Z))) &&
Y->getType() == Z->getType()) {
auto *YZ = Builder.CreateAdd(Y, Z);
auto *NewPow = Builder.CreateIntrinsic(
Intrinsic::powi, {X->getType(), YZ->getType()}, {X, YZ}, &I);
return replaceInstUsesWith(I, NewPow);
}

// exp(X) * exp(Y) -> exp(X + Y)
if (match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X))) &&
match(Op1, m_Intrinsic<Intrinsic::exp>(m_Value(Y)))) {
Value *XY = Builder.CreateFAddFMF(X, Y, &I);
Value *Exp = Builder.CreateUnaryIntrinsic(Intrinsic::exp, XY, &I);
return replaceInstUsesWith(I, Exp);
}

// exp2(X) * exp2(Y) -> exp2(X + Y)
if (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) &&
match(Op1, m_Intrinsic<Intrinsic::exp2>(m_Value(Y)))) {
Value *XY = Builder.CreateFAddFMF(X, Y, &I);
Value *Exp2 = Builder.CreateUnaryIntrinsic(Intrinsic::exp2, XY, &I);
return replaceInstUsesWith(I, Exp2);
}
}

// (X*Y) * X => (X*X) * Y where Y != X
// The purpose is two-fold:
// 1) to form a power expression (of X).
// 2) potentially shorten the critical path: After transformation, the
// latency of the instruction Y is amortized by the expression of X*X,
// and therefore Y is in a "less critical" position compared to what it
// was before the transformation.
if (match(Op0, m_OneUse(m_c_FMul(m_Specific(Op1), m_Value(Y)))) &&
Op1 != Y) {
Value *XX = Builder.CreateFMulFMF(Op1, Op1, &I);
return BinaryOperator::CreateFMulFMF(XX, Y, &I);
}
if (match(Op1, m_OneUse(m_c_FMul(m_Specific(Op0), m_Value(Y)))) &&
Op0 != Y) {
Value *XX = Builder.CreateFMulFMF(Op0, Op0, &I);
return BinaryOperator::CreateFMulFMF(XX, Y, &I);
}
}
if (I.hasAllowReassoc())
if (Instruction *FoldedMul = foldFMulReassoc(I))
return FoldedMul;

// log2(X * 0.5) * Y = log2(X) * Y - Y
if (I.isFast()) {
Expand Down