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InstCombine: Simplify commonIDivTransforms
A helper routine, MultiplyOverflows, was a less efficient reimplementation of APInt's smul_ov and umul_ov. While we are here, clean up the code so it's more uniform. No functionality change intended. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219583 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
parent
e9bc1e8263
commit
05f7e38c0b
@ -81,25 +81,15 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC,
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/// MultiplyOverflows - True if the multiply can not be expressed in an int
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/// this size.
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static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
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uint32_t W = C1->getBitWidth();
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APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
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if (sign) {
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LHSExt = LHSExt.sext(W * 2);
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RHSExt = RHSExt.sext(W * 2);
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} else {
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LHSExt = LHSExt.zext(W * 2);
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RHSExt = RHSExt.zext(W * 2);
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}
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static bool MultiplyOverflows(const APInt &C1, const APInt &C2, APInt &Product,
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bool IsSigned) {
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bool Overflow;
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if (IsSigned)
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Product = C1.smul_ov(C2, Overflow);
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else
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Product = C1.umul_ov(C2, Overflow);
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APInt MulExt = LHSExt * RHSExt;
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if (!sign)
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return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
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APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
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APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
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return MulExt.slt(Min) || MulExt.sgt(Max);
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return Overflow;
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}
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/// \brief True if C2 is a multiple of C1. Quotient contains C2/C1.
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@ -722,83 +712,83 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
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if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
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return &I;
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if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
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if (Instruction *LHS = dyn_cast<Instruction>(Op0)) {
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// (X / C1) / C2 -> X / (C1*C2)
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if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
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if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
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if (!MultiplyOverflows(RHS, LHSRHS,
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I.getOpcode() == Instruction::SDiv))
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return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
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ConstantExpr::getMul(RHS, LHSRHS));
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}
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if (Instruction *LHS = dyn_cast<Instruction>(Op0)) {
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const APInt *C2;
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if (match(Op1, m_APInt(C2))) {
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Value *X;
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const APInt *C1, *C2;
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if (match(RHS, m_APInt(C2))) {
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bool IsSigned = I.getOpcode() == Instruction::SDiv;
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if ((IsSigned && match(LHS, m_NSWMul(m_Value(X), m_APInt(C1)))) ||
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(!IsSigned && match(LHS, m_NUWMul(m_Value(X), m_APInt(C1))))) {
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APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);
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const APInt *C1;
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bool IsSigned = I.getOpcode() == Instruction::SDiv;
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// (X * C1) / C2 -> X / (C2 / C1) if C2 is a multiple of C1.
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if (IsMultiple(*C2, *C1, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient));
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BO->setIsExact(I.isExact());
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return BO;
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}
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// (X / C1) / C2 -> X / (C1*C2)
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if ((IsSigned && match(LHS, m_SDiv(m_Value(X), m_APInt(C1)))) ||
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(!IsSigned && match(LHS, m_UDiv(m_Value(X), m_APInt(C1))))) {
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APInt Product(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);
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if (!MultiplyOverflows(*C1, *C2, Product, IsSigned))
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return BinaryOperator::Create(I.getOpcode(), X,
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ConstantInt::get(I.getType(), Product));
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}
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// (X * C1) / C2 -> X * (C1 / C2) if C1 is a multiple of C2.
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if (IsMultiple(*C1, *C2, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient));
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BO->setHasNoUnsignedWrap(
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!IsSigned &&
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cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap());
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BO->setHasNoSignedWrap(
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cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap());
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return BO;
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}
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if ((IsSigned && match(LHS, m_NSWMul(m_Value(X), m_APInt(C1)))) ||
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(!IsSigned && match(LHS, m_NUWMul(m_Value(X), m_APInt(C1))))) {
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APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);
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// (X * C1) / C2 -> X / (C2 / C1) if C2 is a multiple of C1.
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if (IsMultiple(*C2, *C1, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient));
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BO->setIsExact(I.isExact());
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return BO;
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}
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if ((IsSigned && match(LHS, m_NSWShl(m_Value(X), m_APInt(C1))) &&
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*C1 != C1->getBitWidth() - 1) ||
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(!IsSigned && match(LHS, m_NUWShl(m_Value(X), m_APInt(C1))))) {
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APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);
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APInt C1Shifted = APInt::getOneBitSet(
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C1->getBitWidth(), static_cast<unsigned>(C1->getLimitedValue()));
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// (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of C1.
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if (IsMultiple(*C2, C1Shifted, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient));
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BO->setIsExact(I.isExact());
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return BO;
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}
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// (X << C1) / C2 -> X * (C2 >> C1) if C1 is a multiple of C2.
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if (IsMultiple(C1Shifted, *C2, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient));
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BO->setHasNoUnsignedWrap(
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!IsSigned &&
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cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap());
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BO->setHasNoSignedWrap(
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cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap());
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return BO;
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}
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// (X * C1) / C2 -> X * (C1 / C2) if C1 is a multiple of C2.
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if (IsMultiple(*C1, *C2, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient));
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BO->setHasNoUnsignedWrap(
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!IsSigned &&
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cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap());
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BO->setHasNoSignedWrap(
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cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap());
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return BO;
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}
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}
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}
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if (!RHS->isZero()) { // avoid X udiv 0
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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if ((IsSigned && match(LHS, m_NSWShl(m_Value(X), m_APInt(C1))) &&
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*C1 != C1->getBitWidth() - 1) ||
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(!IsSigned && match(LHS, m_NUWShl(m_Value(X), m_APInt(C1))))) {
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APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);
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APInt C1Shifted = APInt::getOneBitSet(
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C1->getBitWidth(), static_cast<unsigned>(C1->getLimitedValue()));
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// (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of C1.
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if (IsMultiple(*C2, C1Shifted, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient));
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BO->setIsExact(I.isExact());
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return BO;
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}
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// (X << C1) / C2 -> X * (C2 >> C1) if C1 is a multiple of C2.
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if (IsMultiple(C1Shifted, *C2, Quotient, IsSigned)) {
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BinaryOperator *BO = BinaryOperator::Create(
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Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient));
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BO->setHasNoUnsignedWrap(
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!IsSigned &&
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cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap());
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BO->setHasNoSignedWrap(
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cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap());
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return BO;
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}
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}
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if (*C2 != 0) { // avoid X udiv 0
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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}
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}
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