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Diffstat (limited to 'contrib/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 1498 |
1 files changed, 1498 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/contrib/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp new file mode 100644 index 0000000..a554e9f --- /dev/null +++ b/contrib/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -0,0 +1,1498 @@ +//===- InstCombineMulDivRem.cpp -------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the visit functions for mul, fmul, sdiv, udiv, fdiv, +// srem, urem, frem. +// +//===----------------------------------------------------------------------===// + +#include "InstCombineInternal.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/PatternMatch.h" +using namespace llvm; +using namespace PatternMatch; + +#define DEBUG_TYPE "instcombine" + + +/// simplifyValueKnownNonZero - The specific integer value is used in a context +/// where it is known to be non-zero. If this allows us to simplify the +/// computation, do so and return the new operand, otherwise return null. +static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC, + Instruction &CxtI) { + // If V has multiple uses, then we would have to do more analysis to determine + // if this is safe. For example, the use could be in dynamically unreached + // code. + if (!V->hasOneUse()) return nullptr; + + bool MadeChange = false; + + // ((1 << A) >>u B) --> (1 << (A-B)) + // Because V cannot be zero, we know that B is less than A. + Value *A = nullptr, *B = nullptr, *One = nullptr; + if (match(V, m_LShr(m_OneUse(m_Shl(m_Value(One), m_Value(A))), m_Value(B))) && + match(One, m_One())) { + A = IC.Builder->CreateSub(A, B); + return IC.Builder->CreateShl(One, A); + } + + // (PowerOfTwo >>u B) --> isExact since shifting out the result would make it + // inexact. Similarly for <<. + if (BinaryOperator *I = dyn_cast<BinaryOperator>(V)) + if (I->isLogicalShift() && + isKnownToBeAPowerOfTwo(I->getOperand(0), IC.getDataLayout(), false, 0, + IC.getAssumptionCache(), &CxtI, + IC.getDominatorTree())) { + // We know that this is an exact/nuw shift and that the input is a + // non-zero context as well. + if (Value *V2 = simplifyValueKnownNonZero(I->getOperand(0), IC, CxtI)) { + I->setOperand(0, V2); + MadeChange = true; + } + + if (I->getOpcode() == Instruction::LShr && !I->isExact()) { + I->setIsExact(); + MadeChange = true; + } + + if (I->getOpcode() == Instruction::Shl && !I->hasNoUnsignedWrap()) { + I->setHasNoUnsignedWrap(); + MadeChange = true; + } + } + + // TODO: Lots more we could do here: + // If V is a phi node, we can call this on each of its operands. + // "select cond, X, 0" can simplify to "X". + + return MadeChange ? V : nullptr; +} + + +/// MultiplyOverflows - True if the multiply can not be expressed in an int +/// this size. +static bool MultiplyOverflows(const APInt &C1, const APInt &C2, APInt &Product, + bool IsSigned) { + bool Overflow; + if (IsSigned) + Product = C1.smul_ov(C2, Overflow); + else + Product = C1.umul_ov(C2, Overflow); + + return Overflow; +} + +/// \brief True if C2 is a multiple of C1. Quotient contains C2/C1. +static bool IsMultiple(const APInt &C1, const APInt &C2, APInt &Quotient, + bool IsSigned) { + assert(C1.getBitWidth() == C2.getBitWidth() && + "Inconsistent width of constants!"); + + APInt Remainder(C1.getBitWidth(), /*Val=*/0ULL, IsSigned); + if (IsSigned) + APInt::sdivrem(C1, C2, Quotient, Remainder); + else + APInt::udivrem(C1, C2, Quotient, Remainder); + + return Remainder.isMinValue(); +} + +/// \brief A helper routine of InstCombiner::visitMul(). +/// +/// If C is a vector of known powers of 2, then this function returns +/// a new vector obtained from C replacing each element with its logBase2. +/// Return a null pointer otherwise. +static Constant *getLogBase2Vector(ConstantDataVector *CV) { + const APInt *IVal; + SmallVector<Constant *, 4> Elts; + + for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) { + Constant *Elt = CV->getElementAsConstant(I); + if (!match(Elt, m_APInt(IVal)) || !IVal->isPowerOf2()) + return nullptr; + Elts.push_back(ConstantInt::get(Elt->getType(), IVal->logBase2())); + } + + return ConstantVector::get(Elts); +} + +/// \brief Return true if we can prove that: +/// (mul LHS, RHS) === (mul nsw LHS, RHS) +bool InstCombiner::WillNotOverflowSignedMul(Value *LHS, Value *RHS, + Instruction &CxtI) { + // Multiplying n * m significant bits yields a result of n + m significant + // bits. If the total number of significant bits does not exceed the + // result bit width (minus 1), there is no overflow. + // This means if we have enough leading sign bits in the operands + // we can guarantee that the result does not overflow. + // Ref: "Hacker's Delight" by Henry Warren + unsigned BitWidth = LHS->getType()->getScalarSizeInBits(); + + // Note that underestimating the number of sign bits gives a more + // conservative answer. + unsigned SignBits = + ComputeNumSignBits(LHS, 0, &CxtI) + ComputeNumSignBits(RHS, 0, &CxtI); + + // First handle the easy case: if we have enough sign bits there's + // definitely no overflow. + if (SignBits > BitWidth + 1) + return true; + + // There are two ambiguous cases where there can be no overflow: + // SignBits == BitWidth + 1 and + // SignBits == BitWidth + // The second case is difficult to check, therefore we only handle the + // first case. + if (SignBits == BitWidth + 1) { + // It overflows only when both arguments are negative and the true + // product is exactly the minimum negative number. + // E.g. mul i16 with 17 sign bits: 0xff00 * 0xff80 = 0x8000 + // For simplicity we just check if at least one side is not negative. + bool LHSNonNegative, LHSNegative; + bool RHSNonNegative, RHSNegative; + ComputeSignBit(LHS, LHSNonNegative, LHSNegative, /*Depth=*/0, &CxtI); + ComputeSignBit(RHS, RHSNonNegative, RHSNegative, /*Depth=*/0, &CxtI); + if (LHSNonNegative || RHSNonNegative) + return true; + } + return false; +} + +Instruction *InstCombiner::visitMul(BinaryOperator &I) { + bool Changed = SimplifyAssociativeOrCommutative(I); + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifyMulInst(Op0, Op1, DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifyUsingDistributiveLaws(I)) + return ReplaceInstUsesWith(I, V); + + // X * -1 == 0 - X + if (match(Op1, m_AllOnes())) { + BinaryOperator *BO = BinaryOperator::CreateNeg(Op0, I.getName()); + if (I.hasNoSignedWrap()) + BO->setHasNoSignedWrap(); + return BO; + } + + // Also allow combining multiply instructions on vectors. + { + Value *NewOp; + Constant *C1, *C2; + const APInt *IVal; + if (match(&I, m_Mul(m_Shl(m_Value(NewOp), m_Constant(C2)), + m_Constant(C1))) && + match(C1, m_APInt(IVal))) { + // ((X << C2)*C1) == (X * (C1 << C2)) + Constant *Shl = ConstantExpr::getShl(C1, C2); + BinaryOperator *Mul = cast<BinaryOperator>(I.getOperand(0)); + BinaryOperator *BO = BinaryOperator::CreateMul(NewOp, Shl); + if (I.hasNoUnsignedWrap() && Mul->hasNoUnsignedWrap()) + BO->setHasNoUnsignedWrap(); + if (I.hasNoSignedWrap() && Mul->hasNoSignedWrap() && + Shl->isNotMinSignedValue()) + BO->setHasNoSignedWrap(); + return BO; + } + + if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) { + Constant *NewCst = nullptr; + if (match(C1, m_APInt(IVal)) && IVal->isPowerOf2()) + // Replace X*(2^C) with X << C, where C is either a scalar or a splat. + NewCst = ConstantInt::get(NewOp->getType(), IVal->logBase2()); + else if (ConstantDataVector *CV = dyn_cast<ConstantDataVector>(C1)) + // Replace X*(2^C) with X << C, where C is a vector of known + // constant powers of 2. + NewCst = getLogBase2Vector(CV); + + if (NewCst) { + unsigned Width = NewCst->getType()->getPrimitiveSizeInBits(); + BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst); + + if (I.hasNoUnsignedWrap()) + Shl->setHasNoUnsignedWrap(); + if (I.hasNoSignedWrap()) { + uint64_t V; + if (match(NewCst, m_ConstantInt(V)) && V != Width - 1) + Shl->setHasNoSignedWrap(); + } + + return Shl; + } + } + } + + if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { + // (Y - X) * (-(2**n)) -> (X - Y) * (2**n), for positive nonzero n + // (Y + const) * (-(2**n)) -> (-constY) * (2**n), for positive nonzero n + // The "* (2**n)" thus becomes a potential shifting opportunity. + { + const APInt & Val = CI->getValue(); + const APInt &PosVal = Val.abs(); + if (Val.isNegative() && PosVal.isPowerOf2()) { + Value *X = nullptr, *Y = nullptr; + if (Op0->hasOneUse()) { + ConstantInt *C1; + Value *Sub = nullptr; + if (match(Op0, m_Sub(m_Value(Y), m_Value(X)))) + Sub = Builder->CreateSub(X, Y, "suba"); + else if (match(Op0, m_Add(m_Value(Y), m_ConstantInt(C1)))) + Sub = Builder->CreateSub(Builder->CreateNeg(C1), Y, "subc"); + if (Sub) + return + BinaryOperator::CreateMul(Sub, + ConstantInt::get(Y->getType(), PosVal)); + } + } + } + } + + // Simplify mul instructions with a constant RHS. + if (isa<Constant>(Op1)) { + // Try to fold constant mul into select arguments. + if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + + if (isa<PHINode>(Op0)) + if (Instruction *NV = FoldOpIntoPhi(I)) + return NV; + + // Canonicalize (X+C1)*CI -> X*CI+C1*CI. + { + Value *X; + Constant *C1; + if (match(Op0, m_OneUse(m_Add(m_Value(X), m_Constant(C1))))) { + Value *Mul = Builder->CreateMul(C1, Op1); + // Only go forward with the transform if C1*CI simplifies to a tidier + // constant. + if (!match(Mul, m_Mul(m_Value(), m_Value()))) + return BinaryOperator::CreateAdd(Builder->CreateMul(X, Op1), Mul); + } + } + } + + if (Value *Op0v = dyn_castNegVal(Op0)) { // -X * -Y = X*Y + if (Value *Op1v = dyn_castNegVal(Op1)) { + BinaryOperator *BO = BinaryOperator::CreateMul(Op0v, Op1v); + if (I.hasNoSignedWrap() && + match(Op0, m_NSWSub(m_Value(), m_Value())) && + match(Op1, m_NSWSub(m_Value(), m_Value()))) + BO->setHasNoSignedWrap(); + return BO; + } + } + + // (X / Y) * Y = X - (X % Y) + // (X / Y) * -Y = (X % Y) - X + { + Value *Op1C = Op1; + BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0); + if (!BO || + (BO->getOpcode() != Instruction::UDiv && + BO->getOpcode() != Instruction::SDiv)) { + Op1C = Op0; + BO = dyn_cast<BinaryOperator>(Op1); + } + Value *Neg = dyn_castNegVal(Op1C); + if (BO && BO->hasOneUse() && + (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) && + (BO->getOpcode() == Instruction::UDiv || + BO->getOpcode() == Instruction::SDiv)) { + Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1); + + // If the division is exact, X % Y is zero, so we end up with X or -X. + if (PossiblyExactOperator *SDiv = dyn_cast<PossiblyExactOperator>(BO)) + if (SDiv->isExact()) { + if (Op1BO == Op1C) + return ReplaceInstUsesWith(I, Op0BO); + return BinaryOperator::CreateNeg(Op0BO); + } + + Value *Rem; + if (BO->getOpcode() == Instruction::UDiv) + Rem = Builder->CreateURem(Op0BO, Op1BO); + else + Rem = Builder->CreateSRem(Op0BO, Op1BO); + Rem->takeName(BO); + + if (Op1BO == Op1C) + return BinaryOperator::CreateSub(Op0BO, Rem); + return BinaryOperator::CreateSub(Rem, Op0BO); + } + } + + /// i1 mul -> i1 and. + if (I.getType()->getScalarType()->isIntegerTy(1)) + return BinaryOperator::CreateAnd(Op0, Op1); + + // X*(1 << Y) --> X << Y + // (1 << Y)*X --> X << Y + { + Value *Y; + BinaryOperator *BO = nullptr; + bool ShlNSW = false; + if (match(Op0, m_Shl(m_One(), m_Value(Y)))) { + BO = BinaryOperator::CreateShl(Op1, Y); + ShlNSW = cast<ShlOperator>(Op0)->hasNoSignedWrap(); + } else if (match(Op1, m_Shl(m_One(), m_Value(Y)))) { + BO = BinaryOperator::CreateShl(Op0, Y); + ShlNSW = cast<ShlOperator>(Op1)->hasNoSignedWrap(); + } + if (BO) { + if (I.hasNoUnsignedWrap()) + BO->setHasNoUnsignedWrap(); + if (I.hasNoSignedWrap() && ShlNSW) + BO->setHasNoSignedWrap(); + return BO; + } + } + + // If one of the operands of the multiply is a cast from a boolean value, then + // we know the bool is either zero or one, so this is a 'masking' multiply. + // X * Y (where Y is 0 or 1) -> X & (0-Y) + if (!I.getType()->isVectorTy()) { + // -2 is "-1 << 1" so it is all bits set except the low one. + APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true); + + Value *BoolCast = nullptr, *OtherOp = nullptr; + if (MaskedValueIsZero(Op0, Negative2, 0, &I)) + BoolCast = Op0, OtherOp = Op1; + else if (MaskedValueIsZero(Op1, Negative2, 0, &I)) + BoolCast = Op1, OtherOp = Op0; + + if (BoolCast) { + Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()), + BoolCast); + return BinaryOperator::CreateAnd(V, OtherOp); + } + } + + if (!I.hasNoSignedWrap() && WillNotOverflowSignedMul(Op0, Op1, I)) { + Changed = true; + I.setHasNoSignedWrap(true); + } + + if (!I.hasNoUnsignedWrap() && + computeOverflowForUnsignedMul(Op0, Op1, &I) == + OverflowResult::NeverOverflows) { + Changed = true; + I.setHasNoUnsignedWrap(true); + } + + return Changed ? &I : nullptr; +} + +/// Detect pattern log2(Y * 0.5) with corresponding fast math flags. +static void detectLog2OfHalf(Value *&Op, Value *&Y, IntrinsicInst *&Log2) { + if (!Op->hasOneUse()) + return; + + IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op); + if (!II) + return; + if (II->getIntrinsicID() != Intrinsic::log2 || !II->hasUnsafeAlgebra()) + return; + Log2 = II; + + Value *OpLog2Of = II->getArgOperand(0); + if (!OpLog2Of->hasOneUse()) + return; + + Instruction *I = dyn_cast<Instruction>(OpLog2Of); + if (!I) + return; + if (I->getOpcode() != Instruction::FMul || !I->hasUnsafeAlgebra()) + return; + + if (match(I->getOperand(0), m_SpecificFP(0.5))) + Y = I->getOperand(1); + else if (match(I->getOperand(1), m_SpecificFP(0.5))) + Y = I->getOperand(0); +} + +static bool isFiniteNonZeroFp(Constant *C) { + if (C->getType()->isVectorTy()) { + for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; + ++I) { + ConstantFP *CFP = dyn_cast_or_null<ConstantFP>(C->getAggregateElement(I)); + if (!CFP || !CFP->getValueAPF().isFiniteNonZero()) + return false; + } + return true; + } + + return isa<ConstantFP>(C) && + cast<ConstantFP>(C)->getValueAPF().isFiniteNonZero(); +} + +static bool isNormalFp(Constant *C) { + if (C->getType()->isVectorTy()) { + for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; + ++I) { + ConstantFP *CFP = dyn_cast_or_null<ConstantFP>(C->getAggregateElement(I)); + if (!CFP || !CFP->getValueAPF().isNormal()) + return false; + } + return true; + } + + return isa<ConstantFP>(C) && cast<ConstantFP>(C)->getValueAPF().isNormal(); +} + +/// Helper function of InstCombiner::visitFMul(BinaryOperator(). It returns +/// true iff the given value is FMul or FDiv with one and only one operand +/// being a normal constant (i.e. not Zero/NaN/Infinity). +static bool isFMulOrFDivWithConstant(Value *V) { + Instruction *I = dyn_cast<Instruction>(V); + if (!I || (I->getOpcode() != Instruction::FMul && + I->getOpcode() != Instruction::FDiv)) + return false; + + Constant *C0 = dyn_cast<Constant>(I->getOperand(0)); + Constant *C1 = dyn_cast<Constant>(I->getOperand(1)); + + if (C0 && C1) + return false; + + return (C0 && isFiniteNonZeroFp(C0)) || (C1 && isFiniteNonZeroFp(C1)); +} + +/// foldFMulConst() is a helper routine of InstCombiner::visitFMul(). +/// The input \p FMulOrDiv is a FMul/FDiv with one and only one operand +/// being a constant (i.e. isFMulOrFDivWithConstant(FMulOrDiv) == true). +/// This function is to simplify "FMulOrDiv * C" and returns the +/// resulting expression. Note that this function could return NULL in +/// case the constants cannot be folded into a normal floating-point. +/// +Value *InstCombiner::foldFMulConst(Instruction *FMulOrDiv, Constant *C, + Instruction *InsertBefore) { + assert(isFMulOrFDivWithConstant(FMulOrDiv) && "V is invalid"); + + Value *Opnd0 = FMulOrDiv->getOperand(0); + Value *Opnd1 = FMulOrDiv->getOperand(1); + + Constant *C0 = dyn_cast<Constant>(Opnd0); + Constant *C1 = dyn_cast<Constant>(Opnd1); + + BinaryOperator *R = nullptr; + + // (X * C0) * C => X * (C0*C) + if (FMulOrDiv->getOpcode() == Instruction::FMul) { + Constant *F = ConstantExpr::getFMul(C1 ? C1 : C0, C); + if (isNormalFp(F)) + R = BinaryOperator::CreateFMul(C1 ? Opnd0 : Opnd1, F); + } else { + if (C0) { + // (C0 / X) * C => (C0 * C) / X + if (FMulOrDiv->hasOneUse()) { + // It would otherwise introduce another div. + Constant *F = ConstantExpr::getFMul(C0, C); + if (isNormalFp(F)) + R = BinaryOperator::CreateFDiv(F, Opnd1); + } + } else { + // (X / C1) * C => X * (C/C1) if C/C1 is not a denormal + Constant *F = ConstantExpr::getFDiv(C, C1); + if (isNormalFp(F)) { + R = BinaryOperator::CreateFMul(Opnd0, F); + } else { + // (X / C1) * C => X / (C1/C) + Constant *F = ConstantExpr::getFDiv(C1, C); + if (isNormalFp(F)) + R = BinaryOperator::CreateFDiv(Opnd0, F); + } + } + } + + if (R) { + R->setHasUnsafeAlgebra(true); + InsertNewInstWith(R, *InsertBefore); + } + + return R; +} + +Instruction *InstCombiner::visitFMul(BinaryOperator &I) { + bool Changed = SimplifyAssociativeOrCommutative(I); + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (isa<Constant>(Op0)) + std::swap(Op0, Op1); + + if (Value *V = + SimplifyFMulInst(Op0, Op1, I.getFastMathFlags(), DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + bool AllowReassociate = I.hasUnsafeAlgebra(); + + // Simplify mul instructions with a constant RHS. + if (isa<Constant>(Op1)) { + // Try to fold constant mul into select arguments. + if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + + if (isa<PHINode>(Op0)) + if (Instruction *NV = FoldOpIntoPhi(I)) + return NV; + + // (fmul X, -1.0) --> (fsub -0.0, X) + if (match(Op1, m_SpecificFP(-1.0))) { + Constant *NegZero = ConstantFP::getNegativeZero(Op1->getType()); + Instruction *RI = BinaryOperator::CreateFSub(NegZero, Op0); + RI->copyFastMathFlags(&I); + return RI; + } + + Constant *C = cast<Constant>(Op1); + if (AllowReassociate && isFiniteNonZeroFp(C)) { + // Let MDC denote an expression in one of these forms: + // X * C, C/X, X/C, where C is a constant. + // + // Try to simplify "MDC * Constant" + if (isFMulOrFDivWithConstant(Op0)) + if (Value *V = foldFMulConst(cast<Instruction>(Op0), C, &I)) + return ReplaceInstUsesWith(I, V); + + // (MDC +/- C1) * C => (MDC * C) +/- (C1 * C) + Instruction *FAddSub = dyn_cast<Instruction>(Op0); + if (FAddSub && + (FAddSub->getOpcode() == Instruction::FAdd || + FAddSub->getOpcode() == Instruction::FSub)) { + Value *Opnd0 = FAddSub->getOperand(0); + Value *Opnd1 = FAddSub->getOperand(1); + Constant *C0 = dyn_cast<Constant>(Opnd0); + Constant *C1 = dyn_cast<Constant>(Opnd1); + bool Swap = false; + if (C0) { + std::swap(C0, C1); + std::swap(Opnd0, Opnd1); + Swap = true; + } + + if (C1 && isFiniteNonZeroFp(C1) && isFMulOrFDivWithConstant(Opnd0)) { + Value *M1 = ConstantExpr::getFMul(C1, C); + Value *M0 = isNormalFp(cast<Constant>(M1)) ? + foldFMulConst(cast<Instruction>(Opnd0), C, &I) : + nullptr; + if (M0 && M1) { + if (Swap && FAddSub->getOpcode() == Instruction::FSub) + std::swap(M0, M1); + + Instruction *RI = (FAddSub->getOpcode() == Instruction::FAdd) + ? BinaryOperator::CreateFAdd(M0, M1) + : BinaryOperator::CreateFSub(M0, M1); + RI->copyFastMathFlags(&I); + return RI; + } + } + } + } + } + + // sqrt(X) * sqrt(X) -> X + if (AllowReassociate && (Op0 == Op1)) + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op0)) + if (II->getIntrinsicID() == Intrinsic::sqrt) + return ReplaceInstUsesWith(I, II->getOperand(0)); + + // Under unsafe algebra do: + // X * log2(0.5*Y) = X*log2(Y) - X + if (AllowReassociate) { + Value *OpX = nullptr; + Value *OpY = nullptr; + IntrinsicInst *Log2; + detectLog2OfHalf(Op0, OpY, Log2); + if (OpY) { + OpX = Op1; + } else { + detectLog2OfHalf(Op1, OpY, Log2); + if (OpY) { + OpX = Op0; + } + } + // if pattern detected emit alternate sequence + if (OpX && OpY) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->SetFastMathFlags(Log2->getFastMathFlags()); + Log2->setArgOperand(0, OpY); + Value *FMulVal = Builder->CreateFMul(OpX, Log2); + Value *FSub = Builder->CreateFSub(FMulVal, OpX); + FSub->takeName(&I); + return ReplaceInstUsesWith(I, FSub); + } + } + + // Handle symmetric situation in a 2-iteration loop + Value *Opnd0 = Op0; + Value *Opnd1 = Op1; + for (int i = 0; i < 2; i++) { + bool IgnoreZeroSign = I.hasNoSignedZeros(); + if (BinaryOperator::isFNeg(Opnd0, IgnoreZeroSign)) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->SetFastMathFlags(I.getFastMathFlags()); + + Value *N0 = dyn_castFNegVal(Opnd0, IgnoreZeroSign); + Value *N1 = dyn_castFNegVal(Opnd1, IgnoreZeroSign); + + // -X * -Y => X*Y + if (N1) { + Value *FMul = Builder->CreateFMul(N0, N1); + FMul->takeName(&I); + return ReplaceInstUsesWith(I, FMul); + } + + if (Opnd0->hasOneUse()) { + // -X * Y => -(X*Y) (Promote negation as high as possible) + Value *T = Builder->CreateFMul(N0, Opnd1); + Value *Neg = Builder->CreateFNeg(T); + Neg->takeName(&I); + return ReplaceInstUsesWith(I, Neg); + } + } + + // (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 (AllowReassociate) { + Value *Opnd0_0, *Opnd0_1; + if (Opnd0->hasOneUse() && + match(Opnd0, m_FMul(m_Value(Opnd0_0), m_Value(Opnd0_1)))) { + Value *Y = nullptr; + if (Opnd0_0 == Opnd1 && Opnd0_1 != Opnd1) + Y = Opnd0_1; + else if (Opnd0_1 == Opnd1 && Opnd0_0 != Opnd1) + Y = Opnd0_0; + + if (Y) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->SetFastMathFlags(I.getFastMathFlags()); + Value *T = Builder->CreateFMul(Opnd1, Opnd1); + + Value *R = Builder->CreateFMul(T, Y); + R->takeName(&I); + return ReplaceInstUsesWith(I, R); + } + } + } + + if (!isa<Constant>(Op1)) + std::swap(Opnd0, Opnd1); + else + break; + } + + return Changed ? &I : nullptr; +} + +/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select +/// instruction. +bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { + SelectInst *SI = cast<SelectInst>(I.getOperand(1)); + + // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y + int NonNullOperand = -1; + if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1))) + if (ST->isNullValue()) + NonNullOperand = 2; + // div/rem X, (Cond ? Y : 0) -> div/rem X, Y + if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2))) + if (ST->isNullValue()) + NonNullOperand = 1; + + if (NonNullOperand == -1) + return false; + + Value *SelectCond = SI->getOperand(0); + + // Change the div/rem to use 'Y' instead of the select. + I.setOperand(1, SI->getOperand(NonNullOperand)); + + // Okay, we know we replace the operand of the div/rem with 'Y' with no + // problem. However, the select, or the condition of the select may have + // multiple uses. Based on our knowledge that the operand must be non-zero, + // propagate the known value for the select into other uses of it, and + // propagate a known value of the condition into its other users. + + // If the select and condition only have a single use, don't bother with this, + // early exit. + if (SI->use_empty() && SelectCond->hasOneUse()) + return true; + + // Scan the current block backward, looking for other uses of SI. + BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin(); + + while (BBI != BBFront) { + --BBI; + // If we found a call to a function, we can't assume it will return, so + // information from below it cannot be propagated above it. + if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI)) + break; + + // Replace uses of the select or its condition with the known values. + for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end(); + I != E; ++I) { + if (*I == SI) { + *I = SI->getOperand(NonNullOperand); + Worklist.Add(BBI); + } else if (*I == SelectCond) { + *I = Builder->getInt1(NonNullOperand == 1); + Worklist.Add(BBI); + } + } + + // If we past the instruction, quit looking for it. + if (&*BBI == SI) + SI = nullptr; + if (&*BBI == SelectCond) + SelectCond = nullptr; + + // If we ran out of things to eliminate, break out of the loop. + if (!SelectCond && !SI) + break; + + } + return true; +} + + +/// This function implements the transforms common to both integer division +/// instructions (udiv and sdiv). It is called by the visitors to those integer +/// division instructions. +/// @brief Common integer divide transforms +Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + // The RHS is known non-zero. + if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this, I)) { + I.setOperand(1, V); + return &I; + } + + // Handle cases involving: [su]div X, (select Cond, Y, Z) + // This does not apply for fdiv. + if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I)) + return &I; + + if (Instruction *LHS = dyn_cast<Instruction>(Op0)) { + const APInt *C2; + if (match(Op1, m_APInt(C2))) { + Value *X; + const APInt *C1; + bool IsSigned = I.getOpcode() == Instruction::SDiv; + + // (X / C1) / C2 -> X / (C1*C2) + if ((IsSigned && match(LHS, m_SDiv(m_Value(X), m_APInt(C1)))) || + (!IsSigned && match(LHS, m_UDiv(m_Value(X), m_APInt(C1))))) { + APInt Product(C1->getBitWidth(), /*Val=*/0ULL, IsSigned); + if (!MultiplyOverflows(*C1, *C2, Product, IsSigned)) + return BinaryOperator::Create(I.getOpcode(), X, + ConstantInt::get(I.getType(), Product)); + } + + if ((IsSigned && match(LHS, m_NSWMul(m_Value(X), m_APInt(C1)))) || + (!IsSigned && match(LHS, m_NUWMul(m_Value(X), m_APInt(C1))))) { + APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned); + + // (X * C1) / C2 -> X / (C2 / C1) if C2 is a multiple of C1. + if (IsMultiple(*C2, *C1, Quotient, IsSigned)) { + BinaryOperator *BO = BinaryOperator::Create( + I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient)); + BO->setIsExact(I.isExact()); + return BO; + } + + // (X * C1) / C2 -> X * (C1 / C2) if C1 is a multiple of C2. + if (IsMultiple(*C1, *C2, Quotient, IsSigned)) { + BinaryOperator *BO = BinaryOperator::Create( + Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient)); + BO->setHasNoUnsignedWrap( + !IsSigned && + cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap()); + BO->setHasNoSignedWrap( + cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap()); + return BO; + } + } + + if ((IsSigned && match(LHS, m_NSWShl(m_Value(X), m_APInt(C1))) && + *C1 != C1->getBitWidth() - 1) || + (!IsSigned && match(LHS, m_NUWShl(m_Value(X), m_APInt(C1))))) { + APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned); + APInt C1Shifted = APInt::getOneBitSet( + C1->getBitWidth(), static_cast<unsigned>(C1->getLimitedValue())); + + // (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of C1. + if (IsMultiple(*C2, C1Shifted, Quotient, IsSigned)) { + BinaryOperator *BO = BinaryOperator::Create( + I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient)); + BO->setIsExact(I.isExact()); + return BO; + } + + // (X << C1) / C2 -> X * (C2 >> C1) if C1 is a multiple of C2. + if (IsMultiple(C1Shifted, *C2, Quotient, IsSigned)) { + BinaryOperator *BO = BinaryOperator::Create( + Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient)); + BO->setHasNoUnsignedWrap( + !IsSigned && + cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap()); + BO->setHasNoSignedWrap( + cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap()); + return BO; + } + } + + if (*C2 != 0) { // avoid X udiv 0 + if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + if (isa<PHINode>(Op0)) + if (Instruction *NV = FoldOpIntoPhi(I)) + return NV; + } + } + } + + if (ConstantInt *One = dyn_cast<ConstantInt>(Op0)) { + if (One->isOne() && !I.getType()->isIntegerTy(1)) { + bool isSigned = I.getOpcode() == Instruction::SDiv; + if (isSigned) { + // If Op1 is 0 then it's undefined behaviour, if Op1 is 1 then the + // result is one, if Op1 is -1 then the result is minus one, otherwise + // it's zero. + Value *Inc = Builder->CreateAdd(Op1, One); + Value *Cmp = Builder->CreateICmpULT( + Inc, ConstantInt::get(I.getType(), 3)); + return SelectInst::Create(Cmp, Op1, ConstantInt::get(I.getType(), 0)); + } else { + // If Op1 is 0 then it's undefined behaviour. If Op1 is 1 then the + // result is one, otherwise it's zero. + return new ZExtInst(Builder->CreateICmpEQ(Op1, One), I.getType()); + } + } + } + + // See if we can fold away this div instruction. + if (SimplifyDemandedInstructionBits(I)) + return &I; + + // (X - (X rem Y)) / Y -> X / Y; usually originates as ((X / Y) * Y) / Y + Value *X = nullptr, *Z = nullptr; + if (match(Op0, m_Sub(m_Value(X), m_Value(Z)))) { // (X - Z) / Y; Y = Op1 + bool isSigned = I.getOpcode() == Instruction::SDiv; + if ((isSigned && match(Z, m_SRem(m_Specific(X), m_Specific(Op1)))) || + (!isSigned && match(Z, m_URem(m_Specific(X), m_Specific(Op1))))) + return BinaryOperator::Create(I.getOpcode(), X, Op1); + } + + return nullptr; +} + +/// dyn_castZExtVal - Checks if V is a zext or constant that can +/// be truncated to Ty without losing bits. +static Value *dyn_castZExtVal(Value *V, Type *Ty) { + if (ZExtInst *Z = dyn_cast<ZExtInst>(V)) { + if (Z->getSrcTy() == Ty) + return Z->getOperand(0); + } else if (ConstantInt *C = dyn_cast<ConstantInt>(V)) { + if (C->getValue().getActiveBits() <= cast<IntegerType>(Ty)->getBitWidth()) + return ConstantExpr::getTrunc(C, Ty); + } + return nullptr; +} + +namespace { +const unsigned MaxDepth = 6; +typedef Instruction *(*FoldUDivOperandCb)(Value *Op0, Value *Op1, + const BinaryOperator &I, + InstCombiner &IC); + +/// \brief Used to maintain state for visitUDivOperand(). +struct UDivFoldAction { + FoldUDivOperandCb FoldAction; ///< Informs visitUDiv() how to fold this + ///< operand. This can be zero if this action + ///< joins two actions together. + + Value *OperandToFold; ///< Which operand to fold. + union { + Instruction *FoldResult; ///< The instruction returned when FoldAction is + ///< invoked. + + size_t SelectLHSIdx; ///< Stores the LHS action index if this action + ///< joins two actions together. + }; + + UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand) + : FoldAction(FA), OperandToFold(InputOperand), FoldResult(nullptr) {} + UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand, size_t SLHS) + : FoldAction(FA), OperandToFold(InputOperand), SelectLHSIdx(SLHS) {} +}; +} + +// X udiv 2^C -> X >> C +static Instruction *foldUDivPow2Cst(Value *Op0, Value *Op1, + const BinaryOperator &I, InstCombiner &IC) { + const APInt &C = cast<Constant>(Op1)->getUniqueInteger(); + BinaryOperator *LShr = BinaryOperator::CreateLShr( + Op0, ConstantInt::get(Op0->getType(), C.logBase2())); + if (I.isExact()) + LShr->setIsExact(); + return LShr; +} + +// X udiv C, where C >= signbit +static Instruction *foldUDivNegCst(Value *Op0, Value *Op1, + const BinaryOperator &I, InstCombiner &IC) { + Value *ICI = IC.Builder->CreateICmpULT(Op0, cast<ConstantInt>(Op1)); + + return SelectInst::Create(ICI, Constant::getNullValue(I.getType()), + ConstantInt::get(I.getType(), 1)); +} + +// X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2) +static Instruction *foldUDivShl(Value *Op0, Value *Op1, const BinaryOperator &I, + InstCombiner &IC) { + Instruction *ShiftLeft = cast<Instruction>(Op1); + if (isa<ZExtInst>(ShiftLeft)) + ShiftLeft = cast<Instruction>(ShiftLeft->getOperand(0)); + + const APInt &CI = + cast<Constant>(ShiftLeft->getOperand(0))->getUniqueInteger(); + Value *N = ShiftLeft->getOperand(1); + if (CI != 1) + N = IC.Builder->CreateAdd(N, ConstantInt::get(N->getType(), CI.logBase2())); + if (ZExtInst *Z = dyn_cast<ZExtInst>(Op1)) + N = IC.Builder->CreateZExt(N, Z->getDestTy()); + BinaryOperator *LShr = BinaryOperator::CreateLShr(Op0, N); + if (I.isExact()) + LShr->setIsExact(); + return LShr; +} + +// \brief Recursively visits the possible right hand operands of a udiv +// instruction, seeing through select instructions, to determine if we can +// replace the udiv with something simpler. If we find that an operand is not +// able to simplify the udiv, we abort the entire transformation. +static size_t visitUDivOperand(Value *Op0, Value *Op1, const BinaryOperator &I, + SmallVectorImpl<UDivFoldAction> &Actions, + unsigned Depth = 0) { + // Check to see if this is an unsigned division with an exact power of 2, + // if so, convert to a right shift. + if (match(Op1, m_Power2())) { + Actions.push_back(UDivFoldAction(foldUDivPow2Cst, Op1)); + return Actions.size(); + } + + if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) + // X udiv C, where C >= signbit + if (C->getValue().isNegative()) { + Actions.push_back(UDivFoldAction(foldUDivNegCst, C)); + return Actions.size(); + } + + // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2) + if (match(Op1, m_Shl(m_Power2(), m_Value())) || + match(Op1, m_ZExt(m_Shl(m_Power2(), m_Value())))) { + Actions.push_back(UDivFoldAction(foldUDivShl, Op1)); + return Actions.size(); + } + + // The remaining tests are all recursive, so bail out if we hit the limit. + if (Depth++ == MaxDepth) + return 0; + + if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) + if (size_t LHSIdx = + visitUDivOperand(Op0, SI->getOperand(1), I, Actions, Depth)) + if (visitUDivOperand(Op0, SI->getOperand(2), I, Actions, Depth)) { + Actions.push_back(UDivFoldAction(nullptr, Op1, LHSIdx - 1)); + return Actions.size(); + } + + return 0; +} + +Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifyUDivInst(Op0, Op1, DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + // Handle the integer div common cases + if (Instruction *Common = commonIDivTransforms(I)) + return Common; + + // (x lshr C1) udiv C2 --> x udiv (C2 << C1) + { + Value *X; + const APInt *C1, *C2; + if (match(Op0, m_LShr(m_Value(X), m_APInt(C1))) && + match(Op1, m_APInt(C2))) { + bool Overflow; + APInt C2ShlC1 = C2->ushl_ov(*C1, Overflow); + if (!Overflow) { + bool IsExact = I.isExact() && match(Op0, m_Exact(m_Value())); + BinaryOperator *BO = BinaryOperator::CreateUDiv( + X, ConstantInt::get(X->getType(), C2ShlC1)); + if (IsExact) + BO->setIsExact(); + return BO; + } + } + } + + // (zext A) udiv (zext B) --> zext (A udiv B) + if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0)) + if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy())) + return new ZExtInst( + Builder->CreateUDiv(ZOp0->getOperand(0), ZOp1, "div", I.isExact()), + I.getType()); + + // (LHS udiv (select (select (...)))) -> (LHS >> (select (select (...)))) + SmallVector<UDivFoldAction, 6> UDivActions; + if (visitUDivOperand(Op0, Op1, I, UDivActions)) + for (unsigned i = 0, e = UDivActions.size(); i != e; ++i) { + FoldUDivOperandCb Action = UDivActions[i].FoldAction; + Value *ActionOp1 = UDivActions[i].OperandToFold; + Instruction *Inst; + if (Action) + Inst = Action(Op0, ActionOp1, I, *this); + else { + // This action joins two actions together. The RHS of this action is + // simply the last action we processed, we saved the LHS action index in + // the joining action. + size_t SelectRHSIdx = i - 1; + Value *SelectRHS = UDivActions[SelectRHSIdx].FoldResult; + size_t SelectLHSIdx = UDivActions[i].SelectLHSIdx; + Value *SelectLHS = UDivActions[SelectLHSIdx].FoldResult; + Inst = SelectInst::Create(cast<SelectInst>(ActionOp1)->getCondition(), + SelectLHS, SelectRHS); + } + + // If this is the last action to process, return it to the InstCombiner. + // Otherwise, we insert it before the UDiv and record it so that we may + // use it as part of a joining action (i.e., a SelectInst). + if (e - i != 1) { + Inst->insertBefore(&I); + UDivActions[i].FoldResult = Inst; + } else + return Inst; + } + + return nullptr; +} + +Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifySDivInst(Op0, Op1, DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + // Handle the integer div common cases + if (Instruction *Common = commonIDivTransforms(I)) + return Common; + + // sdiv X, -1 == -X + if (match(Op1, m_AllOnes())) + return BinaryOperator::CreateNeg(Op0); + + if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { + // sdiv X, C --> ashr exact X, log2(C) + if (I.isExact() && RHS->getValue().isNonNegative() && + RHS->getValue().isPowerOf2()) { + Value *ShAmt = llvm::ConstantInt::get(RHS->getType(), + RHS->getValue().exactLogBase2()); + return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName()); + } + } + + if (Constant *RHS = dyn_cast<Constant>(Op1)) { + // X/INT_MIN -> X == INT_MIN + if (RHS->isMinSignedValue()) + return new ZExtInst(Builder->CreateICmpEQ(Op0, Op1), I.getType()); + + // -X/C --> X/-C provided the negation doesn't overflow. + Value *X; + if (match(Op0, m_NSWSub(m_Zero(), m_Value(X)))) { + auto *BO = BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(RHS)); + BO->setIsExact(I.isExact()); + return BO; + } + } + + // If the sign bits of both operands are zero (i.e. we can prove they are + // unsigned inputs), turn this into a udiv. + if (I.getType()->isIntegerTy()) { + APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())); + if (MaskedValueIsZero(Op0, Mask, 0, &I)) { + if (MaskedValueIsZero(Op1, Mask, 0, &I)) { + // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set + auto *BO = BinaryOperator::CreateUDiv(Op0, Op1, I.getName()); + BO->setIsExact(I.isExact()); + return BO; + } + + if (isKnownToBeAPowerOfTwo(Op1, DL, /*OrZero*/ true, 0, AC, &I, DT)) { + // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y) + // Safe because the only negative value (1 << Y) can take on is + // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have + // the sign bit set. + auto *BO = BinaryOperator::CreateUDiv(Op0, Op1, I.getName()); + BO->setIsExact(I.isExact()); + return BO; + } + } + } + + return nullptr; +} + +/// CvtFDivConstToReciprocal tries to convert X/C into X*1/C if C not a special +/// FP value and: +/// 1) 1/C is exact, or +/// 2) reciprocal is allowed. +/// If the conversion was successful, the simplified expression "X * 1/C" is +/// returned; otherwise, NULL is returned. +/// +static Instruction *CvtFDivConstToReciprocal(Value *Dividend, Constant *Divisor, + bool AllowReciprocal) { + if (!isa<ConstantFP>(Divisor)) // TODO: handle vectors. + return nullptr; + + const APFloat &FpVal = cast<ConstantFP>(Divisor)->getValueAPF(); + APFloat Reciprocal(FpVal.getSemantics()); + bool Cvt = FpVal.getExactInverse(&Reciprocal); + + if (!Cvt && AllowReciprocal && FpVal.isFiniteNonZero()) { + Reciprocal = APFloat(FpVal.getSemantics(), 1.0f); + (void)Reciprocal.divide(FpVal, APFloat::rmNearestTiesToEven); + Cvt = !Reciprocal.isDenormal(); + } + + if (!Cvt) + return nullptr; + + ConstantFP *R; + R = ConstantFP::get(Dividend->getType()->getContext(), Reciprocal); + return BinaryOperator::CreateFMul(Dividend, R); +} + +Instruction *InstCombiner::visitFDiv(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifyFDivInst(Op0, Op1, I.getFastMathFlags(), + DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + if (isa<Constant>(Op0)) + if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + + bool AllowReassociate = I.hasUnsafeAlgebra(); + bool AllowReciprocal = I.hasAllowReciprocal(); + + if (Constant *Op1C = dyn_cast<Constant>(Op1)) { + if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + + if (AllowReassociate) { + Constant *C1 = nullptr; + Constant *C2 = Op1C; + Value *X; + Instruction *Res = nullptr; + + if (match(Op0, m_FMul(m_Value(X), m_Constant(C1)))) { + // (X*C1)/C2 => X * (C1/C2) + // + Constant *C = ConstantExpr::getFDiv(C1, C2); + if (isNormalFp(C)) + Res = BinaryOperator::CreateFMul(X, C); + } else if (match(Op0, m_FDiv(m_Value(X), m_Constant(C1)))) { + // (X/C1)/C2 => X /(C2*C1) [=> X * 1/(C2*C1) if reciprocal is allowed] + // + Constant *C = ConstantExpr::getFMul(C1, C2); + if (isNormalFp(C)) { + Res = CvtFDivConstToReciprocal(X, C, AllowReciprocal); + if (!Res) + Res = BinaryOperator::CreateFDiv(X, C); + } + } + + if (Res) { + Res->setFastMathFlags(I.getFastMathFlags()); + return Res; + } + } + + // X / C => X * 1/C + if (Instruction *T = CvtFDivConstToReciprocal(Op0, Op1C, AllowReciprocal)) { + T->copyFastMathFlags(&I); + return T; + } + + return nullptr; + } + + if (AllowReassociate && isa<Constant>(Op0)) { + Constant *C1 = cast<Constant>(Op0), *C2; + Constant *Fold = nullptr; + Value *X; + bool CreateDiv = true; + + // C1 / (X*C2) => (C1/C2) / X + if (match(Op1, m_FMul(m_Value(X), m_Constant(C2)))) + Fold = ConstantExpr::getFDiv(C1, C2); + else if (match(Op1, m_FDiv(m_Value(X), m_Constant(C2)))) { + // C1 / (X/C2) => (C1*C2) / X + Fold = ConstantExpr::getFMul(C1, C2); + } else if (match(Op1, m_FDiv(m_Constant(C2), m_Value(X)))) { + // C1 / (C2/X) => (C1/C2) * X + Fold = ConstantExpr::getFDiv(C1, C2); + CreateDiv = false; + } + + if (Fold && isNormalFp(Fold)) { + Instruction *R = CreateDiv ? BinaryOperator::CreateFDiv(Fold, X) + : BinaryOperator::CreateFMul(X, Fold); + R->setFastMathFlags(I.getFastMathFlags()); + return R; + } + return nullptr; + } + + if (AllowReassociate) { + Value *X, *Y; + Value *NewInst = nullptr; + Instruction *SimpR = nullptr; + + if (Op0->hasOneUse() && match(Op0, m_FDiv(m_Value(X), m_Value(Y)))) { + // (X/Y) / Z => X / (Y*Z) + // + if (!isa<Constant>(Y) || !isa<Constant>(Op1)) { + NewInst = Builder->CreateFMul(Y, Op1); + if (Instruction *RI = dyn_cast<Instruction>(NewInst)) { + FastMathFlags Flags = I.getFastMathFlags(); + Flags &= cast<Instruction>(Op0)->getFastMathFlags(); + RI->setFastMathFlags(Flags); + } + SimpR = BinaryOperator::CreateFDiv(X, NewInst); + } + } else if (Op1->hasOneUse() && match(Op1, m_FDiv(m_Value(X), m_Value(Y)))) { + // Z / (X/Y) => Z*Y / X + // + if (!isa<Constant>(Y) || !isa<Constant>(Op0)) { + NewInst = Builder->CreateFMul(Op0, Y); + if (Instruction *RI = dyn_cast<Instruction>(NewInst)) { + FastMathFlags Flags = I.getFastMathFlags(); + Flags &= cast<Instruction>(Op1)->getFastMathFlags(); + RI->setFastMathFlags(Flags); + } + SimpR = BinaryOperator::CreateFDiv(NewInst, X); + } + } + + if (NewInst) { + if (Instruction *T = dyn_cast<Instruction>(NewInst)) + T->setDebugLoc(I.getDebugLoc()); + SimpR->setFastMathFlags(I.getFastMathFlags()); + return SimpR; + } + } + + return nullptr; +} + +/// This function implements the transforms common to both integer remainder +/// instructions (urem and srem). It is called by the visitors to those integer +/// remainder instructions. +/// @brief Common integer remainder transforms +Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + // The RHS is known non-zero. + if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this, I)) { + I.setOperand(1, V); + return &I; + } + + // Handle cases involving: rem X, (select Cond, Y, Z) + if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I)) + return &I; + + if (isa<Constant>(Op1)) { + if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) { + if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) { + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + } else if (isa<PHINode>(Op0I)) { + if (Instruction *NV = FoldOpIntoPhi(I)) + return NV; + } + + // See if we can fold away this rem instruction. + if (SimplifyDemandedInstructionBits(I)) + return &I; + } + } + + return nullptr; +} + +Instruction *InstCombiner::visitURem(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifyURemInst(Op0, Op1, DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + if (Instruction *common = commonIRemTransforms(I)) + return common; + + // (zext A) urem (zext B) --> zext (A urem B) + if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0)) + if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy())) + return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1), + I.getType()); + + // X urem Y -> X and Y-1, where Y is a power of 2, + if (isKnownToBeAPowerOfTwo(Op1, DL, /*OrZero*/ true, 0, AC, &I, DT)) { + Constant *N1 = Constant::getAllOnesValue(I.getType()); + Value *Add = Builder->CreateAdd(Op1, N1); + return BinaryOperator::CreateAnd(Op0, Add); + } + + // 1 urem X -> zext(X != 1) + if (match(Op0, m_One())) { + Value *Cmp = Builder->CreateICmpNE(Op1, Op0); + Value *Ext = Builder->CreateZExt(Cmp, I.getType()); + return ReplaceInstUsesWith(I, Ext); + } + + return nullptr; +} + +Instruction *InstCombiner::visitSRem(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifySRemInst(Op0, Op1, DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + // Handle the integer rem common cases + if (Instruction *Common = commonIRemTransforms(I)) + return Common; + + { + const APInt *Y; + // X % -Y -> X % Y + if (match(Op1, m_APInt(Y)) && Y->isNegative() && !Y->isMinSignedValue()) { + Worklist.AddValue(I.getOperand(1)); + I.setOperand(1, ConstantInt::get(I.getType(), -*Y)); + return &I; + } + } + + // If the sign bits of both operands are zero (i.e. we can prove they are + // unsigned inputs), turn this into a urem. + if (I.getType()->isIntegerTy()) { + APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())); + if (MaskedValueIsZero(Op1, Mask, 0, &I) && + MaskedValueIsZero(Op0, Mask, 0, &I)) { + // X srem Y -> X urem Y, iff X and Y don't have sign bit set + return BinaryOperator::CreateURem(Op0, Op1, I.getName()); + } + } + + // If it's a constant vector, flip any negative values positive. + if (isa<ConstantVector>(Op1) || isa<ConstantDataVector>(Op1)) { + Constant *C = cast<Constant>(Op1); + unsigned VWidth = C->getType()->getVectorNumElements(); + + bool hasNegative = false; + bool hasMissing = false; + for (unsigned i = 0; i != VWidth; ++i) { + Constant *Elt = C->getAggregateElement(i); + if (!Elt) { + hasMissing = true; + break; + } + + if (ConstantInt *RHS = dyn_cast<ConstantInt>(Elt)) + if (RHS->isNegative()) + hasNegative = true; + } + + if (hasNegative && !hasMissing) { + SmallVector<Constant *, 16> Elts(VWidth); + for (unsigned i = 0; i != VWidth; ++i) { + Elts[i] = C->getAggregateElement(i); // Handle undef, etc. + if (ConstantInt *RHS = dyn_cast<ConstantInt>(Elts[i])) { + if (RHS->isNegative()) + Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS)); + } + } + + Constant *NewRHSV = ConstantVector::get(Elts); + if (NewRHSV != C) { // Don't loop on -MININT + Worklist.AddValue(I.getOperand(1)); + I.setOperand(1, NewRHSV); + return &I; + } + } + } + + return nullptr; +} + +Instruction *InstCombiner::visitFRem(BinaryOperator &I) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyVectorOp(I)) + return ReplaceInstUsesWith(I, V); + + if (Value *V = SimplifyFRemInst(Op0, Op1, I.getFastMathFlags(), + DL, TLI, DT, AC)) + return ReplaceInstUsesWith(I, V); + + // Handle cases involving: rem X, (select Cond, Y, Z) + if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I)) + return &I; + + return nullptr; +} |
