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Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 3288 |
1 files changed, 3288 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp new file mode 100644 index 000000000000..4a30b60ca931 --- /dev/null +++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -0,0 +1,3288 @@ +//===- InstCombineAndOrXor.cpp --------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements the visitAnd, visitOr, and visitXor functions. +// +//===----------------------------------------------------------------------===// + +#include "InstCombineInternal.h" +#include "llvm/Analysis/CmpInstAnalysis.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/IR/ConstantRange.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/PatternMatch.h" +using namespace llvm; +using namespace PatternMatch; + +#define DEBUG_TYPE "instcombine" + +/// Similar to getICmpCode but for FCmpInst. This encodes a fcmp predicate into +/// a four bit mask. +static unsigned getFCmpCode(FCmpInst::Predicate CC) { + assert(FCmpInst::FCMP_FALSE <= CC && CC <= FCmpInst::FCMP_TRUE && + "Unexpected FCmp predicate!"); + // Take advantage of the bit pattern of FCmpInst::Predicate here. + // U L G E + static_assert(FCmpInst::FCMP_FALSE == 0, ""); // 0 0 0 0 + static_assert(FCmpInst::FCMP_OEQ == 1, ""); // 0 0 0 1 + static_assert(FCmpInst::FCMP_OGT == 2, ""); // 0 0 1 0 + static_assert(FCmpInst::FCMP_OGE == 3, ""); // 0 0 1 1 + static_assert(FCmpInst::FCMP_OLT == 4, ""); // 0 1 0 0 + static_assert(FCmpInst::FCMP_OLE == 5, ""); // 0 1 0 1 + static_assert(FCmpInst::FCMP_ONE == 6, ""); // 0 1 1 0 + static_assert(FCmpInst::FCMP_ORD == 7, ""); // 0 1 1 1 + static_assert(FCmpInst::FCMP_UNO == 8, ""); // 1 0 0 0 + static_assert(FCmpInst::FCMP_UEQ == 9, ""); // 1 0 0 1 + static_assert(FCmpInst::FCMP_UGT == 10, ""); // 1 0 1 0 + static_assert(FCmpInst::FCMP_UGE == 11, ""); // 1 0 1 1 + static_assert(FCmpInst::FCMP_ULT == 12, ""); // 1 1 0 0 + static_assert(FCmpInst::FCMP_ULE == 13, ""); // 1 1 0 1 + static_assert(FCmpInst::FCMP_UNE == 14, ""); // 1 1 1 0 + static_assert(FCmpInst::FCMP_TRUE == 15, ""); // 1 1 1 1 + return CC; +} + +/// This is the complement of getICmpCode, which turns an opcode and two +/// operands into either a constant true or false, or a brand new ICmp +/// instruction. The sign is passed in to determine which kind of predicate to +/// use in the new icmp instruction. +static Value *getNewICmpValue(unsigned Code, bool Sign, Value *LHS, Value *RHS, + InstCombiner::BuilderTy &Builder) { + ICmpInst::Predicate NewPred; + if (Constant *TorF = getPredForICmpCode(Code, Sign, LHS->getType(), NewPred)) + return TorF; + return Builder.CreateICmp(NewPred, LHS, RHS); +} + +/// This is the complement of getFCmpCode, which turns an opcode and two +/// operands into either a FCmp instruction, or a true/false constant. +static Value *getFCmpValue(unsigned Code, Value *LHS, Value *RHS, + InstCombiner::BuilderTy &Builder) { + const auto Pred = static_cast<FCmpInst::Predicate>(Code); + assert(FCmpInst::FCMP_FALSE <= Pred && Pred <= FCmpInst::FCMP_TRUE && + "Unexpected FCmp predicate!"); + if (Pred == FCmpInst::FCMP_FALSE) + return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); + if (Pred == FCmpInst::FCMP_TRUE) + return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1); + return Builder.CreateFCmp(Pred, LHS, RHS); +} + +/// Transform BITWISE_OP(BSWAP(A),BSWAP(B)) or +/// BITWISE_OP(BSWAP(A), Constant) to BSWAP(BITWISE_OP(A, B)) +/// \param I Binary operator to transform. +/// \return Pointer to node that must replace the original binary operator, or +/// null pointer if no transformation was made. +static Value *SimplifyBSwap(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + assert(I.isBitwiseLogicOp() && "Unexpected opcode for bswap simplifying"); + + Value *OldLHS = I.getOperand(0); + Value *OldRHS = I.getOperand(1); + + Value *NewLHS; + if (!match(OldLHS, m_BSwap(m_Value(NewLHS)))) + return nullptr; + + Value *NewRHS; + const APInt *C; + + if (match(OldRHS, m_BSwap(m_Value(NewRHS)))) { + // OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) ) + if (!OldLHS->hasOneUse() && !OldRHS->hasOneUse()) + return nullptr; + // NewRHS initialized by the matcher. + } else if (match(OldRHS, m_APInt(C))) { + // OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) ) + if (!OldLHS->hasOneUse()) + return nullptr; + NewRHS = ConstantInt::get(I.getType(), C->byteSwap()); + } else + return nullptr; + + Value *BinOp = Builder.CreateBinOp(I.getOpcode(), NewLHS, NewRHS); + Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::bswap, + I.getType()); + return Builder.CreateCall(F, BinOp); +} + +/// This handles expressions of the form ((val OP C1) & C2). Where +/// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. +Instruction *InstCombiner::OptAndOp(BinaryOperator *Op, + ConstantInt *OpRHS, + ConstantInt *AndRHS, + BinaryOperator &TheAnd) { + Value *X = Op->getOperand(0); + + switch (Op->getOpcode()) { + default: break; + case Instruction::Add: + if (Op->hasOneUse()) { + // Adding a one to a single bit bit-field should be turned into an XOR + // of the bit. First thing to check is to see if this AND is with a + // single bit constant. + const APInt &AndRHSV = AndRHS->getValue(); + + // If there is only one bit set. + if (AndRHSV.isPowerOf2()) { + // Ok, at this point, we know that we are masking the result of the + // ADD down to exactly one bit. If the constant we are adding has + // no bits set below this bit, then we can eliminate the ADD. + const APInt& AddRHS = OpRHS->getValue(); + + // Check to see if any bits below the one bit set in AndRHSV are set. + if ((AddRHS & (AndRHSV - 1)).isNullValue()) { + // If not, the only thing that can effect the output of the AND is + // the bit specified by AndRHSV. If that bit is set, the effect of + // the XOR is to toggle the bit. If it is clear, then the ADD has + // no effect. + if ((AddRHS & AndRHSV).isNullValue()) { // Bit is not set, noop + TheAnd.setOperand(0, X); + return &TheAnd; + } else { + // Pull the XOR out of the AND. + Value *NewAnd = Builder.CreateAnd(X, AndRHS); + NewAnd->takeName(Op); + return BinaryOperator::CreateXor(NewAnd, AndRHS); + } + } + } + } + break; + } + return nullptr; +} + +/// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise +/// (V < Lo || V >= Hi). This method expects that Lo < Hi. IsSigned indicates +/// whether to treat V, Lo, and Hi as signed or not. +Value *InstCombiner::insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi, + bool isSigned, bool Inside) { + assert((isSigned ? Lo.slt(Hi) : Lo.ult(Hi)) && + "Lo is not < Hi in range emission code!"); + + Type *Ty = V->getType(); + + // V >= Min && V < Hi --> V < Hi + // V < Min || V >= Hi --> V >= Hi + ICmpInst::Predicate Pred = Inside ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_UGE; + if (isSigned ? Lo.isMinSignedValue() : Lo.isMinValue()) { + Pred = isSigned ? ICmpInst::getSignedPredicate(Pred) : Pred; + return Builder.CreateICmp(Pred, V, ConstantInt::get(Ty, Hi)); + } + + // V >= Lo && V < Hi --> V - Lo u< Hi - Lo + // V < Lo || V >= Hi --> V - Lo u>= Hi - Lo + Value *VMinusLo = + Builder.CreateSub(V, ConstantInt::get(Ty, Lo), V->getName() + ".off"); + Constant *HiMinusLo = ConstantInt::get(Ty, Hi - Lo); + return Builder.CreateICmp(Pred, VMinusLo, HiMinusLo); +} + +/// Classify (icmp eq (A & B), C) and (icmp ne (A & B), C) as matching patterns +/// that can be simplified. +/// One of A and B is considered the mask. The other is the value. This is +/// described as the "AMask" or "BMask" part of the enum. If the enum contains +/// only "Mask", then both A and B can be considered masks. If A is the mask, +/// then it was proven that (A & C) == C. This is trivial if C == A or C == 0. +/// If both A and C are constants, this proof is also easy. +/// For the following explanations, we assume that A is the mask. +/// +/// "AllOnes" declares that the comparison is true only if (A & B) == A or all +/// bits of A are set in B. +/// Example: (icmp eq (A & 3), 3) -> AMask_AllOnes +/// +/// "AllZeros" declares that the comparison is true only if (A & B) == 0 or all +/// bits of A are cleared in B. +/// Example: (icmp eq (A & 3), 0) -> Mask_AllZeroes +/// +/// "Mixed" declares that (A & B) == C and C might or might not contain any +/// number of one bits and zero bits. +/// Example: (icmp eq (A & 3), 1) -> AMask_Mixed +/// +/// "Not" means that in above descriptions "==" should be replaced by "!=". +/// Example: (icmp ne (A & 3), 3) -> AMask_NotAllOnes +/// +/// If the mask A contains a single bit, then the following is equivalent: +/// (icmp eq (A & B), A) equals (icmp ne (A & B), 0) +/// (icmp ne (A & B), A) equals (icmp eq (A & B), 0) +enum MaskedICmpType { + AMask_AllOnes = 1, + AMask_NotAllOnes = 2, + BMask_AllOnes = 4, + BMask_NotAllOnes = 8, + Mask_AllZeros = 16, + Mask_NotAllZeros = 32, + AMask_Mixed = 64, + AMask_NotMixed = 128, + BMask_Mixed = 256, + BMask_NotMixed = 512 +}; + +/// Return the set of patterns (from MaskedICmpType) that (icmp SCC (A & B), C) +/// satisfies. +static unsigned getMaskedICmpType(Value *A, Value *B, Value *C, + ICmpInst::Predicate Pred) { + ConstantInt *ACst = dyn_cast<ConstantInt>(A); + ConstantInt *BCst = dyn_cast<ConstantInt>(B); + ConstantInt *CCst = dyn_cast<ConstantInt>(C); + bool IsEq = (Pred == ICmpInst::ICMP_EQ); + bool IsAPow2 = (ACst && !ACst->isZero() && ACst->getValue().isPowerOf2()); + bool IsBPow2 = (BCst && !BCst->isZero() && BCst->getValue().isPowerOf2()); + unsigned MaskVal = 0; + if (CCst && CCst->isZero()) { + // if C is zero, then both A and B qualify as mask + MaskVal |= (IsEq ? (Mask_AllZeros | AMask_Mixed | BMask_Mixed) + : (Mask_NotAllZeros | AMask_NotMixed | BMask_NotMixed)); + if (IsAPow2) + MaskVal |= (IsEq ? (AMask_NotAllOnes | AMask_NotMixed) + : (AMask_AllOnes | AMask_Mixed)); + if (IsBPow2) + MaskVal |= (IsEq ? (BMask_NotAllOnes | BMask_NotMixed) + : (BMask_AllOnes | BMask_Mixed)); + return MaskVal; + } + + if (A == C) { + MaskVal |= (IsEq ? (AMask_AllOnes | AMask_Mixed) + : (AMask_NotAllOnes | AMask_NotMixed)); + if (IsAPow2) + MaskVal |= (IsEq ? (Mask_NotAllZeros | AMask_NotMixed) + : (Mask_AllZeros | AMask_Mixed)); + } else if (ACst && CCst && ConstantExpr::getAnd(ACst, CCst) == CCst) { + MaskVal |= (IsEq ? AMask_Mixed : AMask_NotMixed); + } + + if (B == C) { + MaskVal |= (IsEq ? (BMask_AllOnes | BMask_Mixed) + : (BMask_NotAllOnes | BMask_NotMixed)); + if (IsBPow2) + MaskVal |= (IsEq ? (Mask_NotAllZeros | BMask_NotMixed) + : (Mask_AllZeros | BMask_Mixed)); + } else if (BCst && CCst && ConstantExpr::getAnd(BCst, CCst) == CCst) { + MaskVal |= (IsEq ? BMask_Mixed : BMask_NotMixed); + } + + return MaskVal; +} + +/// Convert an analysis of a masked ICmp into its equivalent if all boolean +/// operations had the opposite sense. Since each "NotXXX" flag (recording !=) +/// is adjacent to the corresponding normal flag (recording ==), this just +/// involves swapping those bits over. +static unsigned conjugateICmpMask(unsigned Mask) { + unsigned NewMask; + NewMask = (Mask & (AMask_AllOnes | BMask_AllOnes | Mask_AllZeros | + AMask_Mixed | BMask_Mixed)) + << 1; + + NewMask |= (Mask & (AMask_NotAllOnes | BMask_NotAllOnes | Mask_NotAllZeros | + AMask_NotMixed | BMask_NotMixed)) + >> 1; + + return NewMask; +} + +// Adapts the external decomposeBitTestICmp for local use. +static bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred, + Value *&X, Value *&Y, Value *&Z) { + APInt Mask; + if (!llvm::decomposeBitTestICmp(LHS, RHS, Pred, X, Mask)) + return false; + + Y = ConstantInt::get(X->getType(), Mask); + Z = ConstantInt::get(X->getType(), 0); + return true; +} + +/// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E). +/// Return the pattern classes (from MaskedICmpType) for the left hand side and +/// the right hand side as a pair. +/// LHS and RHS are the left hand side and the right hand side ICmps and PredL +/// and PredR are their predicates, respectively. +static +Optional<std::pair<unsigned, unsigned>> +getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C, + Value *&D, Value *&E, ICmpInst *LHS, + ICmpInst *RHS, + ICmpInst::Predicate &PredL, + ICmpInst::Predicate &PredR) { + // vectors are not (yet?) supported. Don't support pointers either. + if (!LHS->getOperand(0)->getType()->isIntegerTy() || + !RHS->getOperand(0)->getType()->isIntegerTy()) + return None; + + // Here comes the tricky part: + // LHS might be of the form L11 & L12 == X, X == L21 & L22, + // and L11 & L12 == L21 & L22. The same goes for RHS. + // Now we must find those components L** and R**, that are equal, so + // that we can extract the parameters A, B, C, D, and E for the canonical + // above. + Value *L1 = LHS->getOperand(0); + Value *L2 = LHS->getOperand(1); + Value *L11, *L12, *L21, *L22; + // Check whether the icmp can be decomposed into a bit test. + if (decomposeBitTestICmp(L1, L2, PredL, L11, L12, L2)) { + L21 = L22 = L1 = nullptr; + } else { + // Look for ANDs in the LHS icmp. + if (!match(L1, m_And(m_Value(L11), m_Value(L12)))) { + // Any icmp can be viewed as being trivially masked; if it allows us to + // remove one, it's worth it. + L11 = L1; + L12 = Constant::getAllOnesValue(L1->getType()); + } + + if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) { + L21 = L2; + L22 = Constant::getAllOnesValue(L2->getType()); + } + } + + // Bail if LHS was a icmp that can't be decomposed into an equality. + if (!ICmpInst::isEquality(PredL)) + return None; + + Value *R1 = RHS->getOperand(0); + Value *R2 = RHS->getOperand(1); + Value *R11, *R12; + bool Ok = false; + if (decomposeBitTestICmp(R1, R2, PredR, R11, R12, R2)) { + if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { + A = R11; + D = R12; + } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { + A = R12; + D = R11; + } else { + return None; + } + E = R2; + R1 = nullptr; + Ok = true; + } else { + if (!match(R1, m_And(m_Value(R11), m_Value(R12)))) { + // As before, model no mask as a trivial mask if it'll let us do an + // optimization. + R11 = R1; + R12 = Constant::getAllOnesValue(R1->getType()); + } + + if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { + A = R11; + D = R12; + E = R2; + Ok = true; + } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { + A = R12; + D = R11; + E = R2; + Ok = true; + } + } + + // Bail if RHS was a icmp that can't be decomposed into an equality. + if (!ICmpInst::isEquality(PredR)) + return None; + + // Look for ANDs on the right side of the RHS icmp. + if (!Ok) { + if (!match(R2, m_And(m_Value(R11), m_Value(R12)))) { + R11 = R2; + R12 = Constant::getAllOnesValue(R2->getType()); + } + + if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { + A = R11; + D = R12; + E = R1; + Ok = true; + } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { + A = R12; + D = R11; + E = R1; + Ok = true; + } else { + return None; + } + } + if (!Ok) + return None; + + if (L11 == A) { + B = L12; + C = L2; + } else if (L12 == A) { + B = L11; + C = L2; + } else if (L21 == A) { + B = L22; + C = L1; + } else if (L22 == A) { + B = L21; + C = L1; + } + + unsigned LeftType = getMaskedICmpType(A, B, C, PredL); + unsigned RightType = getMaskedICmpType(A, D, E, PredR); + return Optional<std::pair<unsigned, unsigned>>(std::make_pair(LeftType, RightType)); +} + +/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) into a single +/// (icmp(A & X) ==/!= Y), where the left-hand side is of type Mask_NotAllZeros +/// and the right hand side is of type BMask_Mixed. For example, +/// (icmp (A & 12) != 0) & (icmp (A & 15) == 8) -> (icmp (A & 15) == 8). +static Value * foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed( + ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, + Value *A, Value *B, Value *C, Value *D, Value *E, + ICmpInst::Predicate PredL, ICmpInst::Predicate PredR, + llvm::InstCombiner::BuilderTy &Builder) { + // We are given the canonical form: + // (icmp ne (A & B), 0) & (icmp eq (A & D), E). + // where D & E == E. + // + // If IsAnd is false, we get it in negated form: + // (icmp eq (A & B), 0) | (icmp ne (A & D), E) -> + // !((icmp ne (A & B), 0) & (icmp eq (A & D), E)). + // + // We currently handle the case of B, C, D, E are constant. + // + ConstantInt *BCst = dyn_cast<ConstantInt>(B); + if (!BCst) + return nullptr; + ConstantInt *CCst = dyn_cast<ConstantInt>(C); + if (!CCst) + return nullptr; + ConstantInt *DCst = dyn_cast<ConstantInt>(D); + if (!DCst) + return nullptr; + ConstantInt *ECst = dyn_cast<ConstantInt>(E); + if (!ECst) + return nullptr; + + ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE; + + // Update E to the canonical form when D is a power of two and RHS is + // canonicalized as, + // (icmp ne (A & D), 0) -> (icmp eq (A & D), D) or + // (icmp ne (A & D), D) -> (icmp eq (A & D), 0). + if (PredR != NewCC) + ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst)); + + // If B or D is zero, skip because if LHS or RHS can be trivially folded by + // other folding rules and this pattern won't apply any more. + if (BCst->getValue() == 0 || DCst->getValue() == 0) + return nullptr; + + // If B and D don't intersect, ie. (B & D) == 0, no folding because we can't + // deduce anything from it. + // For example, + // (icmp ne (A & 12), 0) & (icmp eq (A & 3), 1) -> no folding. + if ((BCst->getValue() & DCst->getValue()) == 0) + return nullptr; + + // If the following two conditions are met: + // + // 1. mask B covers only a single bit that's not covered by mask D, that is, + // (B & (B ^ D)) is a power of 2 (in other words, B minus the intersection of + // B and D has only one bit set) and, + // + // 2. RHS (and E) indicates that the rest of B's bits are zero (in other + // words, the intersection of B and D is zero), that is, ((B & D) & E) == 0 + // + // then that single bit in B must be one and thus the whole expression can be + // folded to + // (A & (B | D)) == (B & (B ^ D)) | E. + // + // For example, + // (icmp ne (A & 12), 0) & (icmp eq (A & 7), 1) -> (icmp eq (A & 15), 9) + // (icmp ne (A & 15), 0) & (icmp eq (A & 7), 0) -> (icmp eq (A & 15), 8) + if ((((BCst->getValue() & DCst->getValue()) & ECst->getValue()) == 0) && + (BCst->getValue() & (BCst->getValue() ^ DCst->getValue())).isPowerOf2()) { + APInt BorD = BCst->getValue() | DCst->getValue(); + APInt BandBxorDorE = (BCst->getValue() & (BCst->getValue() ^ DCst->getValue())) | + ECst->getValue(); + Value *NewMask = ConstantInt::get(BCst->getType(), BorD); + Value *NewMaskedValue = ConstantInt::get(BCst->getType(), BandBxorDorE); + Value *NewAnd = Builder.CreateAnd(A, NewMask); + return Builder.CreateICmp(NewCC, NewAnd, NewMaskedValue); + } + + auto IsSubSetOrEqual = [](ConstantInt *C1, ConstantInt *C2) { + return (C1->getValue() & C2->getValue()) == C1->getValue(); + }; + auto IsSuperSetOrEqual = [](ConstantInt *C1, ConstantInt *C2) { + return (C1->getValue() & C2->getValue()) == C2->getValue(); + }; + + // In the following, we consider only the cases where B is a superset of D, B + // is a subset of D, or B == D because otherwise there's at least one bit + // covered by B but not D, in which case we can't deduce much from it, so + // no folding (aside from the single must-be-one bit case right above.) + // For example, + // (icmp ne (A & 14), 0) & (icmp eq (A & 3), 1) -> no folding. + if (!IsSubSetOrEqual(BCst, DCst) && !IsSuperSetOrEqual(BCst, DCst)) + return nullptr; + + // At this point, either B is a superset of D, B is a subset of D or B == D. + + // If E is zero, if B is a subset of (or equal to) D, LHS and RHS contradict + // and the whole expression becomes false (or true if negated), otherwise, no + // folding. + // For example, + // (icmp ne (A & 3), 0) & (icmp eq (A & 7), 0) -> false. + // (icmp ne (A & 15), 0) & (icmp eq (A & 3), 0) -> no folding. + if (ECst->isZero()) { + if (IsSubSetOrEqual(BCst, DCst)) + return ConstantInt::get(LHS->getType(), !IsAnd); + return nullptr; + } + + // At this point, B, D, E aren't zero and (B & D) == B, (B & D) == D or B == + // D. If B is a superset of (or equal to) D, since E is not zero, LHS is + // subsumed by RHS (RHS implies LHS.) So the whole expression becomes + // RHS. For example, + // (icmp ne (A & 255), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8). + // (icmp ne (A & 15), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8). + if (IsSuperSetOrEqual(BCst, DCst)) + return RHS; + // Otherwise, B is a subset of D. If B and E have a common bit set, + // ie. (B & E) != 0, then LHS is subsumed by RHS. For example. + // (icmp ne (A & 12), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8). + assert(IsSubSetOrEqual(BCst, DCst) && "Precondition due to above code"); + if ((BCst->getValue() & ECst->getValue()) != 0) + return RHS; + // Otherwise, LHS and RHS contradict and the whole expression becomes false + // (or true if negated.) For example, + // (icmp ne (A & 7), 0) & (icmp eq (A & 15), 8) -> false. + // (icmp ne (A & 6), 0) & (icmp eq (A & 15), 8) -> false. + return ConstantInt::get(LHS->getType(), !IsAnd); +} + +/// Try to fold (icmp(A & B) ==/!= 0) &/| (icmp(A & D) ==/!= E) into a single +/// (icmp(A & X) ==/!= Y), where the left-hand side and the right hand side +/// aren't of the common mask pattern type. +static Value *foldLogOpOfMaskedICmpsAsymmetric( + ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, + Value *A, Value *B, Value *C, Value *D, Value *E, + ICmpInst::Predicate PredL, ICmpInst::Predicate PredR, + unsigned LHSMask, unsigned RHSMask, + llvm::InstCombiner::BuilderTy &Builder) { + assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) && + "Expected equality predicates for masked type of icmps."); + // Handle Mask_NotAllZeros-BMask_Mixed cases. + // (icmp ne/eq (A & B), C) &/| (icmp eq/ne (A & D), E), or + // (icmp eq/ne (A & B), C) &/| (icmp ne/eq (A & D), E) + // which gets swapped to + // (icmp ne/eq (A & D), E) &/| (icmp eq/ne (A & B), C). + if (!IsAnd) { + LHSMask = conjugateICmpMask(LHSMask); + RHSMask = conjugateICmpMask(RHSMask); + } + if ((LHSMask & Mask_NotAllZeros) && (RHSMask & BMask_Mixed)) { + if (Value *V = foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed( + LHS, RHS, IsAnd, A, B, C, D, E, + PredL, PredR, Builder)) { + return V; + } + } else if ((LHSMask & BMask_Mixed) && (RHSMask & Mask_NotAllZeros)) { + if (Value *V = foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed( + RHS, LHS, IsAnd, A, D, E, B, C, + PredR, PredL, Builder)) { + return V; + } + } + return nullptr; +} + +/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) +/// into a single (icmp(A & X) ==/!= Y). +static Value *foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, + llvm::InstCombiner::BuilderTy &Builder) { + Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr; + ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); + Optional<std::pair<unsigned, unsigned>> MaskPair = + getMaskedTypeForICmpPair(A, B, C, D, E, LHS, RHS, PredL, PredR); + if (!MaskPair) + return nullptr; + assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) && + "Expected equality predicates for masked type of icmps."); + unsigned LHSMask = MaskPair->first; + unsigned RHSMask = MaskPair->second; + unsigned Mask = LHSMask & RHSMask; + if (Mask == 0) { + // Even if the two sides don't share a common pattern, check if folding can + // still happen. + if (Value *V = foldLogOpOfMaskedICmpsAsymmetric( + LHS, RHS, IsAnd, A, B, C, D, E, PredL, PredR, LHSMask, RHSMask, + Builder)) + return V; + return nullptr; + } + + // In full generality: + // (icmp (A & B) Op C) | (icmp (A & D) Op E) + // == ![ (icmp (A & B) !Op C) & (icmp (A & D) !Op E) ] + // + // If the latter can be converted into (icmp (A & X) Op Y) then the former is + // equivalent to (icmp (A & X) !Op Y). + // + // Therefore, we can pretend for the rest of this function that we're dealing + // with the conjunction, provided we flip the sense of any comparisons (both + // input and output). + + // In most cases we're going to produce an EQ for the "&&" case. + ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE; + if (!IsAnd) { + // Convert the masking analysis into its equivalent with negated + // comparisons. + Mask = conjugateICmpMask(Mask); + } + + if (Mask & Mask_AllZeros) { + // (icmp eq (A & B), 0) & (icmp eq (A & D), 0) + // -> (icmp eq (A & (B|D)), 0) + Value *NewOr = Builder.CreateOr(B, D); + Value *NewAnd = Builder.CreateAnd(A, NewOr); + // We can't use C as zero because we might actually handle + // (icmp ne (A & B), B) & (icmp ne (A & D), D) + // with B and D, having a single bit set. + Value *Zero = Constant::getNullValue(A->getType()); + return Builder.CreateICmp(NewCC, NewAnd, Zero); + } + if (Mask & BMask_AllOnes) { + // (icmp eq (A & B), B) & (icmp eq (A & D), D) + // -> (icmp eq (A & (B|D)), (B|D)) + Value *NewOr = Builder.CreateOr(B, D); + Value *NewAnd = Builder.CreateAnd(A, NewOr); + return Builder.CreateICmp(NewCC, NewAnd, NewOr); + } + if (Mask & AMask_AllOnes) { + // (icmp eq (A & B), A) & (icmp eq (A & D), A) + // -> (icmp eq (A & (B&D)), A) + Value *NewAnd1 = Builder.CreateAnd(B, D); + Value *NewAnd2 = Builder.CreateAnd(A, NewAnd1); + return Builder.CreateICmp(NewCC, NewAnd2, A); + } + + // Remaining cases assume at least that B and D are constant, and depend on + // their actual values. This isn't strictly necessary, just a "handle the + // easy cases for now" decision. + ConstantInt *BCst = dyn_cast<ConstantInt>(B); + if (!BCst) + return nullptr; + ConstantInt *DCst = dyn_cast<ConstantInt>(D); + if (!DCst) + return nullptr; + + if (Mask & (Mask_NotAllZeros | BMask_NotAllOnes)) { + // (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and + // (icmp ne (A & B), B) & (icmp ne (A & D), D) + // -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0) + // Only valid if one of the masks is a superset of the other (check "B&D" is + // the same as either B or D). + APInt NewMask = BCst->getValue() & DCst->getValue(); + + if (NewMask == BCst->getValue()) + return LHS; + else if (NewMask == DCst->getValue()) + return RHS; + } + + if (Mask & AMask_NotAllOnes) { + // (icmp ne (A & B), B) & (icmp ne (A & D), D) + // -> (icmp ne (A & B), A) or (icmp ne (A & D), A) + // Only valid if one of the masks is a superset of the other (check "B|D" is + // the same as either B or D). + APInt NewMask = BCst->getValue() | DCst->getValue(); + + if (NewMask == BCst->getValue()) + return LHS; + else if (NewMask == DCst->getValue()) + return RHS; + } + + if (Mask & BMask_Mixed) { + // (icmp eq (A & B), C) & (icmp eq (A & D), E) + // We already know that B & C == C && D & E == E. + // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of + // C and E, which are shared by both the mask B and the mask D, don't + // contradict, then we can transform to + // -> (icmp eq (A & (B|D)), (C|E)) + // Currently, we only handle the case of B, C, D, and E being constant. + // We can't simply use C and E because we might actually handle + // (icmp ne (A & B), B) & (icmp eq (A & D), D) + // with B and D, having a single bit set. + ConstantInt *CCst = dyn_cast<ConstantInt>(C); + if (!CCst) + return nullptr; + ConstantInt *ECst = dyn_cast<ConstantInt>(E); + if (!ECst) + return nullptr; + if (PredL != NewCC) + CCst = cast<ConstantInt>(ConstantExpr::getXor(BCst, CCst)); + if (PredR != NewCC) + ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst)); + + // If there is a conflict, we should actually return a false for the + // whole construct. + if (((BCst->getValue() & DCst->getValue()) & + (CCst->getValue() ^ ECst->getValue())).getBoolValue()) + return ConstantInt::get(LHS->getType(), !IsAnd); + + Value *NewOr1 = Builder.CreateOr(B, D); + Value *NewOr2 = ConstantExpr::getOr(CCst, ECst); + Value *NewAnd = Builder.CreateAnd(A, NewOr1); + return Builder.CreateICmp(NewCC, NewAnd, NewOr2); + } + + return nullptr; +} + +/// Try to fold a signed range checked with lower bound 0 to an unsigned icmp. +/// Example: (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n +/// If \p Inverted is true then the check is for the inverted range, e.g. +/// (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n +Value *InstCombiner::simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, + bool Inverted) { + // Check the lower range comparison, e.g. x >= 0 + // InstCombine already ensured that if there is a constant it's on the RHS. + ConstantInt *RangeStart = dyn_cast<ConstantInt>(Cmp0->getOperand(1)); + if (!RangeStart) + return nullptr; + + ICmpInst::Predicate Pred0 = (Inverted ? Cmp0->getInversePredicate() : + Cmp0->getPredicate()); + + // Accept x > -1 or x >= 0 (after potentially inverting the predicate). + if (!((Pred0 == ICmpInst::ICMP_SGT && RangeStart->isMinusOne()) || + (Pred0 == ICmpInst::ICMP_SGE && RangeStart->isZero()))) + return nullptr; + + ICmpInst::Predicate Pred1 = (Inverted ? Cmp1->getInversePredicate() : + Cmp1->getPredicate()); + + Value *Input = Cmp0->getOperand(0); + Value *RangeEnd; + if (Cmp1->getOperand(0) == Input) { + // For the upper range compare we have: icmp x, n + RangeEnd = Cmp1->getOperand(1); + } else if (Cmp1->getOperand(1) == Input) { + // For the upper range compare we have: icmp n, x + RangeEnd = Cmp1->getOperand(0); + Pred1 = ICmpInst::getSwappedPredicate(Pred1); + } else { + return nullptr; + } + + // Check the upper range comparison, e.g. x < n + ICmpInst::Predicate NewPred; + switch (Pred1) { + case ICmpInst::ICMP_SLT: NewPred = ICmpInst::ICMP_ULT; break; + case ICmpInst::ICMP_SLE: NewPred = ICmpInst::ICMP_ULE; break; + default: return nullptr; + } + + // This simplification is only valid if the upper range is not negative. + KnownBits Known = computeKnownBits(RangeEnd, /*Depth=*/0, Cmp1); + if (!Known.isNonNegative()) + return nullptr; + + if (Inverted) + NewPred = ICmpInst::getInversePredicate(NewPred); + + return Builder.CreateICmp(NewPred, Input, RangeEnd); +} + +static Value * +foldAndOrOfEqualityCmpsWithConstants(ICmpInst *LHS, ICmpInst *RHS, + bool JoinedByAnd, + InstCombiner::BuilderTy &Builder) { + Value *X = LHS->getOperand(0); + if (X != RHS->getOperand(0)) + return nullptr; + + const APInt *C1, *C2; + if (!match(LHS->getOperand(1), m_APInt(C1)) || + !match(RHS->getOperand(1), m_APInt(C2))) + return nullptr; + + // We only handle (X != C1 && X != C2) and (X == C1 || X == C2). + ICmpInst::Predicate Pred = LHS->getPredicate(); + if (Pred != RHS->getPredicate()) + return nullptr; + if (JoinedByAnd && Pred != ICmpInst::ICMP_NE) + return nullptr; + if (!JoinedByAnd && Pred != ICmpInst::ICMP_EQ) + return nullptr; + + // The larger unsigned constant goes on the right. + if (C1->ugt(*C2)) + std::swap(C1, C2); + + APInt Xor = *C1 ^ *C2; + if (Xor.isPowerOf2()) { + // If LHSC and RHSC differ by only one bit, then set that bit in X and + // compare against the larger constant: + // (X == C1 || X == C2) --> (X | (C1 ^ C2)) == C2 + // (X != C1 && X != C2) --> (X | (C1 ^ C2)) != C2 + // We choose an 'or' with a Pow2 constant rather than the inverse mask with + // 'and' because that may lead to smaller codegen from a smaller constant. + Value *Or = Builder.CreateOr(X, ConstantInt::get(X->getType(), Xor)); + return Builder.CreateICmp(Pred, Or, ConstantInt::get(X->getType(), *C2)); + } + + // Special case: get the ordering right when the values wrap around zero. + // Ie, we assumed the constants were unsigned when swapping earlier. + if (C1->isNullValue() && C2->isAllOnesValue()) + std::swap(C1, C2); + + if (*C1 == *C2 - 1) { + // (X == 13 || X == 14) --> X - 13 <=u 1 + // (X != 13 && X != 14) --> X - 13 >u 1 + // An 'add' is the canonical IR form, so favor that over a 'sub'. + Value *Add = Builder.CreateAdd(X, ConstantInt::get(X->getType(), -(*C1))); + auto NewPred = JoinedByAnd ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_ULE; + return Builder.CreateICmp(NewPred, Add, ConstantInt::get(X->getType(), 1)); + } + + return nullptr; +} + +// Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2) +// Fold (!iszero(A & K1) & !iszero(A & K2)) -> (A & (K1 | K2)) == (K1 | K2) +Value *InstCombiner::foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS, ICmpInst *RHS, + bool JoinedByAnd, + Instruction &CxtI) { + ICmpInst::Predicate Pred = LHS->getPredicate(); + if (Pred != RHS->getPredicate()) + return nullptr; + if (JoinedByAnd && Pred != ICmpInst::ICMP_NE) + return nullptr; + if (!JoinedByAnd && Pred != ICmpInst::ICMP_EQ) + return nullptr; + + // TODO support vector splats + ConstantInt *LHSC = dyn_cast<ConstantInt>(LHS->getOperand(1)); + ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS->getOperand(1)); + if (!LHSC || !RHSC || !LHSC->isZero() || !RHSC->isZero()) + return nullptr; + + Value *A, *B, *C, *D; + if (match(LHS->getOperand(0), m_And(m_Value(A), m_Value(B))) && + match(RHS->getOperand(0), m_And(m_Value(C), m_Value(D)))) { + if (A == D || B == D) + std::swap(C, D); + if (B == C) + std::swap(A, B); + + if (A == C && + isKnownToBeAPowerOfTwo(B, false, 0, &CxtI) && + isKnownToBeAPowerOfTwo(D, false, 0, &CxtI)) { + Value *Mask = Builder.CreateOr(B, D); + Value *Masked = Builder.CreateAnd(A, Mask); + auto NewPred = JoinedByAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE; + return Builder.CreateICmp(NewPred, Masked, Mask); + } + } + + return nullptr; +} + +/// General pattern: +/// X & Y +/// +/// Where Y is checking that all the high bits (covered by a mask 4294967168) +/// are uniform, i.e. %arg & 4294967168 can be either 4294967168 or 0 +/// Pattern can be one of: +/// %t = add i32 %arg, 128 +/// %r = icmp ult i32 %t, 256 +/// Or +/// %t0 = shl i32 %arg, 24 +/// %t1 = ashr i32 %t0, 24 +/// %r = icmp eq i32 %t1, %arg +/// Or +/// %t0 = trunc i32 %arg to i8 +/// %t1 = sext i8 %t0 to i32 +/// %r = icmp eq i32 %t1, %arg +/// This pattern is a signed truncation check. +/// +/// And X is checking that some bit in that same mask is zero. +/// I.e. can be one of: +/// %r = icmp sgt i32 %arg, -1 +/// Or +/// %t = and i32 %arg, 2147483648 +/// %r = icmp eq i32 %t, 0 +/// +/// Since we are checking that all the bits in that mask are the same, +/// and a particular bit is zero, what we are really checking is that all the +/// masked bits are zero. +/// So this should be transformed to: +/// %r = icmp ult i32 %arg, 128 +static Value *foldSignedTruncationCheck(ICmpInst *ICmp0, ICmpInst *ICmp1, + Instruction &CxtI, + InstCombiner::BuilderTy &Builder) { + assert(CxtI.getOpcode() == Instruction::And); + + // Match icmp ult (add %arg, C01), C1 (C1 == C01 << 1; powers of two) + auto tryToMatchSignedTruncationCheck = [](ICmpInst *ICmp, Value *&X, + APInt &SignBitMask) -> bool { + CmpInst::Predicate Pred; + const APInt *I01, *I1; // powers of two; I1 == I01 << 1 + if (!(match(ICmp, + m_ICmp(Pred, m_Add(m_Value(X), m_Power2(I01)), m_Power2(I1))) && + Pred == ICmpInst::ICMP_ULT && I1->ugt(*I01) && I01->shl(1) == *I1)) + return false; + // Which bit is the new sign bit as per the 'signed truncation' pattern? + SignBitMask = *I01; + return true; + }; + + // One icmp needs to be 'signed truncation check'. + // We need to match this first, else we will mismatch commutative cases. + Value *X1; + APInt HighestBit; + ICmpInst *OtherICmp; + if (tryToMatchSignedTruncationCheck(ICmp1, X1, HighestBit)) + OtherICmp = ICmp0; + else if (tryToMatchSignedTruncationCheck(ICmp0, X1, HighestBit)) + OtherICmp = ICmp1; + else + return nullptr; + + assert(HighestBit.isPowerOf2() && "expected to be power of two (non-zero)"); + + // Try to match/decompose into: icmp eq (X & Mask), 0 + auto tryToDecompose = [](ICmpInst *ICmp, Value *&X, + APInt &UnsetBitsMask) -> bool { + CmpInst::Predicate Pred = ICmp->getPredicate(); + // Can it be decomposed into icmp eq (X & Mask), 0 ? + if (llvm::decomposeBitTestICmp(ICmp->getOperand(0), ICmp->getOperand(1), + Pred, X, UnsetBitsMask, + /*LookThroughTrunc=*/false) && + Pred == ICmpInst::ICMP_EQ) + return true; + // Is it icmp eq (X & Mask), 0 already? + const APInt *Mask; + if (match(ICmp, m_ICmp(Pred, m_And(m_Value(X), m_APInt(Mask)), m_Zero())) && + Pred == ICmpInst::ICMP_EQ) { + UnsetBitsMask = *Mask; + return true; + } + return false; + }; + + // And the other icmp needs to be decomposable into a bit test. + Value *X0; + APInt UnsetBitsMask; + if (!tryToDecompose(OtherICmp, X0, UnsetBitsMask)) + return nullptr; + + assert(!UnsetBitsMask.isNullValue() && "empty mask makes no sense."); + + // Are they working on the same value? + Value *X; + if (X1 == X0) { + // Ok as is. + X = X1; + } else if (match(X0, m_Trunc(m_Specific(X1)))) { + UnsetBitsMask = UnsetBitsMask.zext(X1->getType()->getScalarSizeInBits()); + X = X1; + } else + return nullptr; + + // So which bits should be uniform as per the 'signed truncation check'? + // (all the bits starting with (i.e. including) HighestBit) + APInt SignBitsMask = ~(HighestBit - 1U); + + // UnsetBitsMask must have some common bits with SignBitsMask, + if (!UnsetBitsMask.intersects(SignBitsMask)) + return nullptr; + + // Does UnsetBitsMask contain any bits outside of SignBitsMask? + if (!UnsetBitsMask.isSubsetOf(SignBitsMask)) { + APInt OtherHighestBit = (~UnsetBitsMask) + 1U; + if (!OtherHighestBit.isPowerOf2()) + return nullptr; + HighestBit = APIntOps::umin(HighestBit, OtherHighestBit); + } + // Else, if it does not, then all is ok as-is. + + // %r = icmp ult %X, SignBit + return Builder.CreateICmpULT(X, ConstantInt::get(X->getType(), HighestBit), + CxtI.getName() + ".simplified"); +} + +/// Reduce a pair of compares that check if a value has exactly 1 bit set. +static Value *foldIsPowerOf2(ICmpInst *Cmp0, ICmpInst *Cmp1, bool JoinedByAnd, + InstCombiner::BuilderTy &Builder) { + // Handle 'and' / 'or' commutation: make the equality check the first operand. + if (JoinedByAnd && Cmp1->getPredicate() == ICmpInst::ICMP_NE) + std::swap(Cmp0, Cmp1); + else if (!JoinedByAnd && Cmp1->getPredicate() == ICmpInst::ICMP_EQ) + std::swap(Cmp0, Cmp1); + + // (X != 0) && (ctpop(X) u< 2) --> ctpop(X) == 1 + CmpInst::Predicate Pred0, Pred1; + Value *X; + if (JoinedByAnd && match(Cmp0, m_ICmp(Pred0, m_Value(X), m_ZeroInt())) && + match(Cmp1, m_ICmp(Pred1, m_Intrinsic<Intrinsic::ctpop>(m_Specific(X)), + m_SpecificInt(2))) && + Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_ULT) { + Value *CtPop = Cmp1->getOperand(0); + return Builder.CreateICmpEQ(CtPop, ConstantInt::get(CtPop->getType(), 1)); + } + // (X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1 + if (!JoinedByAnd && match(Cmp0, m_ICmp(Pred0, m_Value(X), m_ZeroInt())) && + match(Cmp1, m_ICmp(Pred1, m_Intrinsic<Intrinsic::ctpop>(m_Specific(X)), + m_SpecificInt(1))) && + Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_UGT) { + Value *CtPop = Cmp1->getOperand(0); + return Builder.CreateICmpNE(CtPop, ConstantInt::get(CtPop->getType(), 1)); + } + return nullptr; +} + +/// Commuted variants are assumed to be handled by calling this function again +/// with the parameters swapped. +static Value *foldUnsignedUnderflowCheck(ICmpInst *ZeroICmp, + ICmpInst *UnsignedICmp, bool IsAnd, + const SimplifyQuery &Q, + InstCombiner::BuilderTy &Builder) { + Value *ZeroCmpOp; + ICmpInst::Predicate EqPred; + if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(ZeroCmpOp), m_Zero())) || + !ICmpInst::isEquality(EqPred)) + return nullptr; + + auto IsKnownNonZero = [&](Value *V) { + return isKnownNonZero(V, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT); + }; + + ICmpInst::Predicate UnsignedPred; + + Value *A, *B; + if (match(UnsignedICmp, + m_c_ICmp(UnsignedPred, m_Specific(ZeroCmpOp), m_Value(A))) && + match(ZeroCmpOp, m_c_Add(m_Specific(A), m_Value(B))) && + (ZeroICmp->hasOneUse() || UnsignedICmp->hasOneUse())) { + if (UnsignedICmp->getOperand(0) != ZeroCmpOp) + UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); + + auto GetKnownNonZeroAndOther = [&](Value *&NonZero, Value *&Other) { + if (!IsKnownNonZero(NonZero)) + std::swap(NonZero, Other); + return IsKnownNonZero(NonZero); + }; + + // Given ZeroCmpOp = (A + B) + // ZeroCmpOp <= A && ZeroCmpOp != 0 --> (0-B) < A + // ZeroCmpOp > A || ZeroCmpOp == 0 --> (0-B) >= A + // + // ZeroCmpOp < A && ZeroCmpOp != 0 --> (0-X) < Y iff + // ZeroCmpOp >= A || ZeroCmpOp == 0 --> (0-X) >= Y iff + // with X being the value (A/B) that is known to be non-zero, + // and Y being remaining value. + if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && + IsAnd) + return Builder.CreateICmpULT(Builder.CreateNeg(B), A); + if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE && + IsAnd && GetKnownNonZeroAndOther(B, A)) + return Builder.CreateICmpULT(Builder.CreateNeg(B), A); + if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && + !IsAnd) + return Builder.CreateICmpUGE(Builder.CreateNeg(B), A); + if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ && + !IsAnd && GetKnownNonZeroAndOther(B, A)) + return Builder.CreateICmpUGE(Builder.CreateNeg(B), A); + } + + Value *Base, *Offset; + if (!match(ZeroCmpOp, m_Sub(m_Value(Base), m_Value(Offset)))) + return nullptr; + + if (!match(UnsignedICmp, + m_c_ICmp(UnsignedPred, m_Specific(Base), m_Specific(Offset))) || + !ICmpInst::isUnsigned(UnsignedPred)) + return nullptr; + if (UnsignedICmp->getOperand(0) != Base) + UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); + + // Base >=/> Offset && (Base - Offset) != 0 <--> Base > Offset + // (no overflow and not null) + if ((UnsignedPred == ICmpInst::ICMP_UGE || + UnsignedPred == ICmpInst::ICMP_UGT) && + EqPred == ICmpInst::ICMP_NE && IsAnd) + return Builder.CreateICmpUGT(Base, Offset); + + // Base <=/< Offset || (Base - Offset) == 0 <--> Base <= Offset + // (overflow or null) + if ((UnsignedPred == ICmpInst::ICMP_ULE || + UnsignedPred == ICmpInst::ICMP_ULT) && + EqPred == ICmpInst::ICMP_EQ && !IsAnd) + return Builder.CreateICmpULE(Base, Offset); + + // Base <= Offset && (Base - Offset) != 0 --> Base < Offset + if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && + IsAnd) + return Builder.CreateICmpULT(Base, Offset); + + // Base > Offset || (Base - Offset) == 0 --> Base >= Offset + if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && + !IsAnd) + return Builder.CreateICmpUGE(Base, Offset); + + return nullptr; +} + +/// Fold (icmp)&(icmp) if possible. +Value *InstCombiner::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS, + Instruction &CxtI) { + const SimplifyQuery Q = SQ.getWithInstruction(&CxtI); + + // Fold (!iszero(A & K1) & !iszero(A & K2)) -> (A & (K1 | K2)) == (K1 | K2) + // if K1 and K2 are a one-bit mask. + if (Value *V = foldAndOrOfICmpsOfAndWithPow2(LHS, RHS, true, CxtI)) + return V; + + ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); + + // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B) + if (predicatesFoldable(PredL, PredR)) { + if (LHS->getOperand(0) == RHS->getOperand(1) && + LHS->getOperand(1) == RHS->getOperand(0)) + LHS->swapOperands(); + if (LHS->getOperand(0) == RHS->getOperand(0) && + LHS->getOperand(1) == RHS->getOperand(1)) { + Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); + unsigned Code = getICmpCode(LHS) & getICmpCode(RHS); + bool IsSigned = LHS->isSigned() || RHS->isSigned(); + return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder); + } + } + + // handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E) + if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, true, Builder)) + return V; + + // E.g. (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n + if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/false)) + return V; + + // E.g. (icmp slt x, n) & (icmp sge x, 0) --> icmp ult x, n + if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/false)) + return V; + + if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, true, Builder)) + return V; + + if (Value *V = foldSignedTruncationCheck(LHS, RHS, CxtI, Builder)) + return V; + + if (Value *V = foldIsPowerOf2(LHS, RHS, true /* JoinedByAnd */, Builder)) + return V; + + if (Value *X = + foldUnsignedUnderflowCheck(LHS, RHS, /*IsAnd=*/true, Q, Builder)) + return X; + if (Value *X = + foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/true, Q, Builder)) + return X; + + // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2). + Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0); + ConstantInt *LHSC = dyn_cast<ConstantInt>(LHS->getOperand(1)); + ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS->getOperand(1)); + if (!LHSC || !RHSC) + return nullptr; + + if (LHSC == RHSC && PredL == PredR) { + // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C) + // where C is a power of 2 or + // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0) + if ((PredL == ICmpInst::ICMP_ULT && LHSC->getValue().isPowerOf2()) || + (PredL == ICmpInst::ICMP_EQ && LHSC->isZero())) { + Value *NewOr = Builder.CreateOr(LHS0, RHS0); + return Builder.CreateICmp(PredL, NewOr, LHSC); + } + } + + // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2 + // where CMAX is the all ones value for the truncated type, + // iff the lower bits of C2 and CA are zero. + if (PredL == ICmpInst::ICMP_EQ && PredL == PredR && LHS->hasOneUse() && + RHS->hasOneUse()) { + Value *V; + ConstantInt *AndC, *SmallC = nullptr, *BigC = nullptr; + + // (trunc x) == C1 & (and x, CA) == C2 + // (and x, CA) == C2 & (trunc x) == C1 + if (match(RHS0, m_Trunc(m_Value(V))) && + match(LHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) { + SmallC = RHSC; + BigC = LHSC; + } else if (match(LHS0, m_Trunc(m_Value(V))) && + match(RHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) { + SmallC = LHSC; + BigC = RHSC; + } + + if (SmallC && BigC) { + unsigned BigBitSize = BigC->getType()->getBitWidth(); + unsigned SmallBitSize = SmallC->getType()->getBitWidth(); + + // Check that the low bits are zero. + APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize); + if ((Low & AndC->getValue()).isNullValue() && + (Low & BigC->getValue()).isNullValue()) { + Value *NewAnd = Builder.CreateAnd(V, Low | AndC->getValue()); + APInt N = SmallC->getValue().zext(BigBitSize) | BigC->getValue(); + Value *NewVal = ConstantInt::get(AndC->getType()->getContext(), N); + return Builder.CreateICmp(PredL, NewAnd, NewVal); + } + } + } + + // From here on, we only handle: + // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler. + if (LHS0 != RHS0) + return nullptr; + + // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere. + if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE || + PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE || + PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE || + PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE) + return nullptr; + + // We can't fold (ugt x, C) & (sgt x, C2). + if (!predicatesFoldable(PredL, PredR)) + return nullptr; + + // Ensure that the larger constant is on the RHS. + bool ShouldSwap; + if (CmpInst::isSigned(PredL) || + (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR))) + ShouldSwap = LHSC->getValue().sgt(RHSC->getValue()); + else + ShouldSwap = LHSC->getValue().ugt(RHSC->getValue()); + + if (ShouldSwap) { + std::swap(LHS, RHS); + std::swap(LHSC, RHSC); + std::swap(PredL, PredR); + } + + // At this point, we know we have two icmp instructions + // comparing a value against two constants and and'ing the result + // together. Because of the above check, we know that we only have + // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know + // (from the icmp folding check above), that the two constants + // are not equal and that the larger constant is on the RHS + assert(LHSC != RHSC && "Compares not folded above?"); + + switch (PredL) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_NE: + switch (PredR) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_ULT: + // (X != 13 & X u< 14) -> X < 13 + if (LHSC->getValue() == (RHSC->getValue() - 1)) + return Builder.CreateICmpULT(LHS0, LHSC); + if (LHSC->isZero()) // (X != 0 & X u< C) -> X-1 u< C-1 + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), + false, true); + break; // (X != 13 & X u< 15) -> no change + case ICmpInst::ICMP_SLT: + // (X != 13 & X s< 14) -> X < 13 + if (LHSC->getValue() == (RHSC->getValue() - 1)) + return Builder.CreateICmpSLT(LHS0, LHSC); + // (X != INT_MIN & X s< C) -> X-(INT_MIN+1) u< (C-(INT_MIN+1)) + if (LHSC->isMinValue(true)) + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), + true, true); + break; // (X != 13 & X s< 15) -> no change + case ICmpInst::ICMP_NE: + // Potential folds for this case should already be handled. + break; + } + break; + case ICmpInst::ICMP_UGT: + switch (PredR) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_NE: + // (X u> 13 & X != 14) -> X u> 14 + if (RHSC->getValue() == (LHSC->getValue() + 1)) + return Builder.CreateICmp(PredL, LHS0, RHSC); + // X u> C & X != UINT_MAX -> (X-(C+1)) u< UINT_MAX-(C+1) + if (RHSC->isMaxValue(false)) + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), + false, true); + break; // (X u> 13 & X != 15) -> no change + case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) u< 1 + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), + false, true); + } + break; + case ICmpInst::ICMP_SGT: + switch (PredR) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_NE: + // (X s> 13 & X != 14) -> X s> 14 + if (RHSC->getValue() == (LHSC->getValue() + 1)) + return Builder.CreateICmp(PredL, LHS0, RHSC); + // X s> C & X != INT_MAX -> (X-(C+1)) u< INT_MAX-(C+1) + if (RHSC->isMaxValue(true)) + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), + true, true); + break; // (X s> 13 & X != 15) -> no change + case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) u< 1 + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true, + true); + } + break; + } + + return nullptr; +} + +Value *InstCombiner::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) { + Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); + Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); + FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); + + if (LHS0 == RHS1 && RHS0 == LHS1) { + // Swap RHS operands to match LHS. + PredR = FCmpInst::getSwappedPredicate(PredR); + std::swap(RHS0, RHS1); + } + + // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y). + // Suppose the relation between x and y is R, where R is one of + // U(1000), L(0100), G(0010) or E(0001), and CC0 and CC1 are the bitmasks for + // testing the desired relations. + // + // Since (R & CC0) and (R & CC1) are either R or 0, we actually have this: + // bool(R & CC0) && bool(R & CC1) + // = bool((R & CC0) & (R & CC1)) + // = bool(R & (CC0 & CC1)) <= by re-association, commutation, and idempotency + // + // Since (R & CC0) and (R & CC1) are either R or 0, we actually have this: + // bool(R & CC0) || bool(R & CC1) + // = bool((R & CC0) | (R & CC1)) + // = bool(R & (CC0 | CC1)) <= by reversed distribution (contribution? ;) + if (LHS0 == RHS0 && LHS1 == RHS1) { + unsigned FCmpCodeL = getFCmpCode(PredL); + unsigned FCmpCodeR = getFCmpCode(PredR); + unsigned NewPred = IsAnd ? FCmpCodeL & FCmpCodeR : FCmpCodeL | FCmpCodeR; + return getFCmpValue(NewPred, LHS0, LHS1, Builder); + } + + if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) || + (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) { + if (LHS0->getType() != RHS0->getType()) + return nullptr; + + // FCmp canonicalization ensures that (fcmp ord/uno X, X) and + // (fcmp ord/uno X, C) will be transformed to (fcmp X, +0.0). + if (match(LHS1, m_PosZeroFP()) && match(RHS1, m_PosZeroFP())) + // Ignore the constants because they are obviously not NANs: + // (fcmp ord x, 0.0) & (fcmp ord y, 0.0) -> (fcmp ord x, y) + // (fcmp uno x, 0.0) | (fcmp uno y, 0.0) -> (fcmp uno x, y) + return Builder.CreateFCmp(PredL, LHS0, RHS0); + } + + return nullptr; +} + +/// This a limited reassociation for a special case (see above) where we are +/// checking if two values are either both NAN (unordered) or not-NAN (ordered). +/// This could be handled more generally in '-reassociation', but it seems like +/// an unlikely pattern for a large number of logic ops and fcmps. +static Instruction *reassociateFCmps(BinaryOperator &BO, + InstCombiner::BuilderTy &Builder) { + Instruction::BinaryOps Opcode = BO.getOpcode(); + assert((Opcode == Instruction::And || Opcode == Instruction::Or) && + "Expecting and/or op for fcmp transform"); + + // There are 4 commuted variants of the pattern. Canonicalize operands of this + // logic op so an fcmp is operand 0 and a matching logic op is operand 1. + Value *Op0 = BO.getOperand(0), *Op1 = BO.getOperand(1), *X; + FCmpInst::Predicate Pred; + if (match(Op1, m_FCmp(Pred, m_Value(), m_AnyZeroFP()))) + std::swap(Op0, Op1); + + // Match inner binop and the predicate for combining 2 NAN checks into 1. + BinaryOperator *BO1; + FCmpInst::Predicate NanPred = Opcode == Instruction::And ? FCmpInst::FCMP_ORD + : FCmpInst::FCMP_UNO; + if (!match(Op0, m_FCmp(Pred, m_Value(X), m_AnyZeroFP())) || Pred != NanPred || + !match(Op1, m_BinOp(BO1)) || BO1->getOpcode() != Opcode) + return nullptr; + + // The inner logic op must have a matching fcmp operand. + Value *BO10 = BO1->getOperand(0), *BO11 = BO1->getOperand(1), *Y; + if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) || + Pred != NanPred || X->getType() != Y->getType()) + std::swap(BO10, BO11); + + if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) || + Pred != NanPred || X->getType() != Y->getType()) + return nullptr; + + // and (fcmp ord X, 0), (and (fcmp ord Y, 0), Z) --> and (fcmp ord X, Y), Z + // or (fcmp uno X, 0), (or (fcmp uno Y, 0), Z) --> or (fcmp uno X, Y), Z + Value *NewFCmp = Builder.CreateFCmp(Pred, X, Y); + if (auto *NewFCmpInst = dyn_cast<FCmpInst>(NewFCmp)) { + // Intersect FMF from the 2 source fcmps. + NewFCmpInst->copyIRFlags(Op0); + NewFCmpInst->andIRFlags(BO10); + } + return BinaryOperator::Create(Opcode, NewFCmp, BO11); +} + +/// Match De Morgan's Laws: +/// (~A & ~B) == (~(A | B)) +/// (~A | ~B) == (~(A & B)) +static Instruction *matchDeMorgansLaws(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + auto Opcode = I.getOpcode(); + assert((Opcode == Instruction::And || Opcode == Instruction::Or) && + "Trying to match De Morgan's Laws with something other than and/or"); + + // Flip the logic operation. + Opcode = (Opcode == Instruction::And) ? Instruction::Or : Instruction::And; + + Value *A, *B; + if (match(I.getOperand(0), m_OneUse(m_Not(m_Value(A)))) && + match(I.getOperand(1), m_OneUse(m_Not(m_Value(B)))) && + !isFreeToInvert(A, A->hasOneUse()) && + !isFreeToInvert(B, B->hasOneUse())) { + Value *AndOr = Builder.CreateBinOp(Opcode, A, B, I.getName() + ".demorgan"); + return BinaryOperator::CreateNot(AndOr); + } + + return nullptr; +} + +bool InstCombiner::shouldOptimizeCast(CastInst *CI) { + Value *CastSrc = CI->getOperand(0); + + // Noop casts and casts of constants should be eliminated trivially. + if (CI->getSrcTy() == CI->getDestTy() || isa<Constant>(CastSrc)) + return false; + + // If this cast is paired with another cast that can be eliminated, we prefer + // to have it eliminated. + if (const auto *PrecedingCI = dyn_cast<CastInst>(CastSrc)) + if (isEliminableCastPair(PrecedingCI, CI)) + return false; + + return true; +} + +/// Fold {and,or,xor} (cast X), C. +static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast, + InstCombiner::BuilderTy &Builder) { + Constant *C = dyn_cast<Constant>(Logic.getOperand(1)); + if (!C) + return nullptr; + + auto LogicOpc = Logic.getOpcode(); + Type *DestTy = Logic.getType(); + Type *SrcTy = Cast->getSrcTy(); + + // Move the logic operation ahead of a zext or sext if the constant is + // unchanged in the smaller source type. Performing the logic in a smaller + // type may provide more information to later folds, and the smaller logic + // instruction may be cheaper (particularly in the case of vectors). + Value *X; + if (match(Cast, m_OneUse(m_ZExt(m_Value(X))))) { + Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy); + Constant *ZextTruncC = ConstantExpr::getZExt(TruncC, DestTy); + if (ZextTruncC == C) { + // LogicOpc (zext X), C --> zext (LogicOpc X, C) + Value *NewOp = Builder.CreateBinOp(LogicOpc, X, TruncC); + return new ZExtInst(NewOp, DestTy); + } + } + + if (match(Cast, m_OneUse(m_SExt(m_Value(X))))) { + Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy); + Constant *SextTruncC = ConstantExpr::getSExt(TruncC, DestTy); + if (SextTruncC == C) { + // LogicOpc (sext X), C --> sext (LogicOpc X, C) + Value *NewOp = Builder.CreateBinOp(LogicOpc, X, TruncC); + return new SExtInst(NewOp, DestTy); + } + } + + return nullptr; +} + +/// Fold {and,or,xor} (cast X), Y. +Instruction *InstCombiner::foldCastedBitwiseLogic(BinaryOperator &I) { + auto LogicOpc = I.getOpcode(); + assert(I.isBitwiseLogicOp() && "Unexpected opcode for bitwise logic folding"); + + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + CastInst *Cast0 = dyn_cast<CastInst>(Op0); + if (!Cast0) + return nullptr; + + // This must be a cast from an integer or integer vector source type to allow + // transformation of the logic operation to the source type. + Type *DestTy = I.getType(); + Type *SrcTy = Cast0->getSrcTy(); + if (!SrcTy->isIntOrIntVectorTy()) + return nullptr; + + if (Instruction *Ret = foldLogicCastConstant(I, Cast0, Builder)) + return Ret; + + CastInst *Cast1 = dyn_cast<CastInst>(Op1); + if (!Cast1) + return nullptr; + + // Both operands of the logic operation are casts. The casts must be of the + // same type for reduction. + auto CastOpcode = Cast0->getOpcode(); + if (CastOpcode != Cast1->getOpcode() || SrcTy != Cast1->getSrcTy()) + return nullptr; + + Value *Cast0Src = Cast0->getOperand(0); + Value *Cast1Src = Cast1->getOperand(0); + + // fold logic(cast(A), cast(B)) -> cast(logic(A, B)) + if (shouldOptimizeCast(Cast0) && shouldOptimizeCast(Cast1)) { + Value *NewOp = Builder.CreateBinOp(LogicOpc, Cast0Src, Cast1Src, + I.getName()); + return CastInst::Create(CastOpcode, NewOp, DestTy); + } + + // For now, only 'and'/'or' have optimizations after this. + if (LogicOpc == Instruction::Xor) + return nullptr; + + // If this is logic(cast(icmp), cast(icmp)), try to fold this even if the + // cast is otherwise not optimizable. This happens for vector sexts. + ICmpInst *ICmp0 = dyn_cast<ICmpInst>(Cast0Src); + ICmpInst *ICmp1 = dyn_cast<ICmpInst>(Cast1Src); + if (ICmp0 && ICmp1) { + Value *Res = LogicOpc == Instruction::And ? foldAndOfICmps(ICmp0, ICmp1, I) + : foldOrOfICmps(ICmp0, ICmp1, I); + if (Res) + return CastInst::Create(CastOpcode, Res, DestTy); + return nullptr; + } + + // If this is logic(cast(fcmp), cast(fcmp)), try to fold this even if the + // cast is otherwise not optimizable. This happens for vector sexts. + FCmpInst *FCmp0 = dyn_cast<FCmpInst>(Cast0Src); + FCmpInst *FCmp1 = dyn_cast<FCmpInst>(Cast1Src); + if (FCmp0 && FCmp1) + if (Value *R = foldLogicOfFCmps(FCmp0, FCmp1, LogicOpc == Instruction::And)) + return CastInst::Create(CastOpcode, R, DestTy); + + return nullptr; +} + +static Instruction *foldAndToXor(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + assert(I.getOpcode() == Instruction::And); + Value *Op0 = I.getOperand(0); + Value *Op1 = I.getOperand(1); + Value *A, *B; + + // Operand complexity canonicalization guarantees that the 'or' is Op0. + // (A | B) & ~(A & B) --> A ^ B + // (A | B) & ~(B & A) --> A ^ B + if (match(&I, m_BinOp(m_Or(m_Value(A), m_Value(B)), + m_Not(m_c_And(m_Deferred(A), m_Deferred(B)))))) + return BinaryOperator::CreateXor(A, B); + + // (A | ~B) & (~A | B) --> ~(A ^ B) + // (A | ~B) & (B | ~A) --> ~(A ^ B) + // (~B | A) & (~A | B) --> ~(A ^ B) + // (~B | A) & (B | ~A) --> ~(A ^ B) + if (Op0->hasOneUse() || Op1->hasOneUse()) + if (match(&I, m_BinOp(m_c_Or(m_Value(A), m_Not(m_Value(B))), + m_c_Or(m_Not(m_Deferred(A)), m_Deferred(B))))) + return BinaryOperator::CreateNot(Builder.CreateXor(A, B)); + + return nullptr; +} + +static Instruction *foldOrToXor(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + assert(I.getOpcode() == Instruction::Or); + Value *Op0 = I.getOperand(0); + Value *Op1 = I.getOperand(1); + Value *A, *B; + + // Operand complexity canonicalization guarantees that the 'and' is Op0. + // (A & B) | ~(A | B) --> ~(A ^ B) + // (A & B) | ~(B | A) --> ~(A ^ B) + if (Op0->hasOneUse() || Op1->hasOneUse()) + if (match(Op0, m_And(m_Value(A), m_Value(B))) && + match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) + return BinaryOperator::CreateNot(Builder.CreateXor(A, B)); + + // (A & ~B) | (~A & B) --> A ^ B + // (A & ~B) | (B & ~A) --> A ^ B + // (~B & A) | (~A & B) --> A ^ B + // (~B & A) | (B & ~A) --> A ^ B + if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && + match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))) + return BinaryOperator::CreateXor(A, B); + + return nullptr; +} + +/// Return true if a constant shift amount is always less than the specified +/// bit-width. If not, the shift could create poison in the narrower type. +static bool canNarrowShiftAmt(Constant *C, unsigned BitWidth) { + if (auto *ScalarC = dyn_cast<ConstantInt>(C)) + return ScalarC->getZExtValue() < BitWidth; + + if (C->getType()->isVectorTy()) { + // Check each element of a constant vector. + unsigned NumElts = C->getType()->getVectorNumElements(); + for (unsigned i = 0; i != NumElts; ++i) { + Constant *Elt = C->getAggregateElement(i); + if (!Elt) + return false; + if (isa<UndefValue>(Elt)) + continue; + auto *CI = dyn_cast<ConstantInt>(Elt); + if (!CI || CI->getZExtValue() >= BitWidth) + return false; + } + return true; + } + + // The constant is a constant expression or unknown. + return false; +} + +/// Try to use narrower ops (sink zext ops) for an 'and' with binop operand and +/// a common zext operand: and (binop (zext X), C), (zext X). +Instruction *InstCombiner::narrowMaskedBinOp(BinaryOperator &And) { + // This transform could also apply to {or, and, xor}, but there are better + // folds for those cases, so we don't expect those patterns here. AShr is not + // handled because it should always be transformed to LShr in this sequence. + // The subtract transform is different because it has a constant on the left. + // Add/mul commute the constant to RHS; sub with constant RHS becomes add. + Value *Op0 = And.getOperand(0), *Op1 = And.getOperand(1); + Constant *C; + if (!match(Op0, m_OneUse(m_Add(m_Specific(Op1), m_Constant(C)))) && + !match(Op0, m_OneUse(m_Mul(m_Specific(Op1), m_Constant(C)))) && + !match(Op0, m_OneUse(m_LShr(m_Specific(Op1), m_Constant(C)))) && + !match(Op0, m_OneUse(m_Shl(m_Specific(Op1), m_Constant(C)))) && + !match(Op0, m_OneUse(m_Sub(m_Constant(C), m_Specific(Op1))))) + return nullptr; + + Value *X; + if (!match(Op1, m_ZExt(m_Value(X))) || Op1->hasNUsesOrMore(3)) + return nullptr; + + Type *Ty = And.getType(); + if (!isa<VectorType>(Ty) && !shouldChangeType(Ty, X->getType())) + return nullptr; + + // If we're narrowing a shift, the shift amount must be safe (less than the + // width) in the narrower type. If the shift amount is greater, instsimplify + // usually handles that case, but we can't guarantee/assert it. + Instruction::BinaryOps Opc = cast<BinaryOperator>(Op0)->getOpcode(); + if (Opc == Instruction::LShr || Opc == Instruction::Shl) + if (!canNarrowShiftAmt(C, X->getType()->getScalarSizeInBits())) + return nullptr; + + // and (sub C, (zext X)), (zext X) --> zext (and (sub C', X), X) + // and (binop (zext X), C), (zext X) --> zext (and (binop X, C'), X) + Value *NewC = ConstantExpr::getTrunc(C, X->getType()); + Value *NewBO = Opc == Instruction::Sub ? Builder.CreateBinOp(Opc, NewC, X) + : Builder.CreateBinOp(Opc, X, NewC); + return new ZExtInst(Builder.CreateAnd(NewBO, X), Ty); +} + +// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches +// here. We should standardize that construct where it is needed or choose some +// other way to ensure that commutated variants of patterns are not missed. +Instruction *InstCombiner::visitAnd(BinaryOperator &I) { + if (Value *V = SimplifyAndInst(I.getOperand(0), I.getOperand(1), + SQ.getWithInstruction(&I))) + return replaceInstUsesWith(I, V); + + if (SimplifyAssociativeOrCommutative(I)) + return &I; + + if (Instruction *X = foldVectorBinop(I)) + return X; + + // See if we can simplify any instructions used by the instruction whose sole + // purpose is to compute bits we don't care about. + if (SimplifyDemandedInstructionBits(I)) + return &I; + + // Do this before using distributive laws to catch simple and/or/not patterns. + if (Instruction *Xor = foldAndToXor(I, Builder)) + return Xor; + + // (A|B)&(A|C) -> A|(B&C) etc + if (Value *V = SimplifyUsingDistributiveLaws(I)) + return replaceInstUsesWith(I, V); + + if (Value *V = SimplifyBSwap(I, Builder)) + return replaceInstUsesWith(I, V); + + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + const APInt *C; + if (match(Op1, m_APInt(C))) { + Value *X, *Y; + if (match(Op0, m_OneUse(m_LogicalShift(m_One(), m_Value(X)))) && + C->isOneValue()) { + // (1 << X) & 1 --> zext(X == 0) + // (1 >> X) & 1 --> zext(X == 0) + Value *IsZero = Builder.CreateICmpEQ(X, ConstantInt::get(I.getType(), 0)); + return new ZExtInst(IsZero, I.getType()); + } + + const APInt *XorC; + if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_APInt(XorC))))) { + // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) + Constant *NewC = ConstantInt::get(I.getType(), *C & *XorC); + Value *And = Builder.CreateAnd(X, Op1); + And->takeName(Op0); + return BinaryOperator::CreateXor(And, NewC); + } + + const APInt *OrC; + if (match(Op0, m_OneUse(m_Or(m_Value(X), m_APInt(OrC))))) { + // (X | C1) & C2 --> (X & C2^(C1&C2)) | (C1&C2) + // NOTE: This reduces the number of bits set in the & mask, which + // can expose opportunities for store narrowing for scalars. + // NOTE: SimplifyDemandedBits should have already removed bits from C1 + // that aren't set in C2. Meaning we can replace (C1&C2) with C1 in + // above, but this feels safer. + APInt Together = *C & *OrC; + Value *And = Builder.CreateAnd(X, ConstantInt::get(I.getType(), + Together ^ *C)); + And->takeName(Op0); + return BinaryOperator::CreateOr(And, ConstantInt::get(I.getType(), + Together)); + } + + // If the mask is only needed on one incoming arm, push the 'and' op up. + if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_Value(Y)))) || + match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) { + APInt NotAndMask(~(*C)); + BinaryOperator::BinaryOps BinOp = cast<BinaryOperator>(Op0)->getOpcode(); + if (MaskedValueIsZero(X, NotAndMask, 0, &I)) { + // Not masking anything out for the LHS, move mask to RHS. + // and ({x}or X, Y), C --> {x}or X, (and Y, C) + Value *NewRHS = Builder.CreateAnd(Y, Op1, Y->getName() + ".masked"); + return BinaryOperator::Create(BinOp, X, NewRHS); + } + if (!isa<Constant>(Y) && MaskedValueIsZero(Y, NotAndMask, 0, &I)) { + // Not masking anything out for the RHS, move mask to LHS. + // and ({x}or X, Y), C --> {x}or (and X, C), Y + Value *NewLHS = Builder.CreateAnd(X, Op1, X->getName() + ".masked"); + return BinaryOperator::Create(BinOp, NewLHS, Y); + } + } + + } + + if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) { + const APInt &AndRHSMask = AndRHS->getValue(); + + // Optimize a variety of ((val OP C1) & C2) combinations... + if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { + // ((C1 OP zext(X)) & C2) -> zext((C1-X) & C2) if C2 fits in the bitwidth + // of X and OP behaves well when given trunc(C1) and X. + // TODO: Do this for vectors by using m_APInt isntead of m_ConstantInt. + switch (Op0I->getOpcode()) { + default: + break; + case Instruction::Xor: + case Instruction::Or: + case Instruction::Mul: + case Instruction::Add: + case Instruction::Sub: + Value *X; + ConstantInt *C1; + // TODO: The one use restrictions could be relaxed a little if the AND + // is going to be removed. + if (match(Op0I, m_OneUse(m_c_BinOp(m_OneUse(m_ZExt(m_Value(X))), + m_ConstantInt(C1))))) { + if (AndRHSMask.isIntN(X->getType()->getScalarSizeInBits())) { + auto *TruncC1 = ConstantExpr::getTrunc(C1, X->getType()); + Value *BinOp; + Value *Op0LHS = Op0I->getOperand(0); + if (isa<ZExtInst>(Op0LHS)) + BinOp = Builder.CreateBinOp(Op0I->getOpcode(), X, TruncC1); + else + BinOp = Builder.CreateBinOp(Op0I->getOpcode(), TruncC1, X); + auto *TruncC2 = ConstantExpr::getTrunc(AndRHS, X->getType()); + auto *And = Builder.CreateAnd(BinOp, TruncC2); + return new ZExtInst(And, I.getType()); + } + } + } + + if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) + if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I)) + return Res; + } + + // If this is an integer truncation, and if the source is an 'and' with + // immediate, transform it. This frequently occurs for bitfield accesses. + { + Value *X = nullptr; ConstantInt *YC = nullptr; + if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) { + // Change: and (trunc (and X, YC) to T), C2 + // into : and (trunc X to T), trunc(YC) & C2 + // This will fold the two constants together, which may allow + // other simplifications. + Value *NewCast = Builder.CreateTrunc(X, I.getType(), "and.shrunk"); + Constant *C3 = ConstantExpr::getTrunc(YC, I.getType()); + C3 = ConstantExpr::getAnd(C3, AndRHS); + return BinaryOperator::CreateAnd(NewCast, C3); + } + } + } + + if (Instruction *Z = narrowMaskedBinOp(I)) + return Z; + + if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I)) + return FoldedLogic; + + if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder)) + return DeMorgan; + + { + Value *A, *B, *C; + // A & (A ^ B) --> A & ~B + if (match(Op1, m_OneUse(m_c_Xor(m_Specific(Op0), m_Value(B))))) + return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(B)); + // (A ^ B) & A --> A & ~B + if (match(Op0, m_OneUse(m_c_Xor(m_Specific(Op1), m_Value(B))))) + return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(B)); + + // (A ^ B) & ((B ^ C) ^ A) -> (A ^ B) & ~C + if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) + if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A)))) + if (Op1->hasOneUse() || isFreeToInvert(C, C->hasOneUse())) + return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(C)); + + // ((A ^ C) ^ B) & (B ^ A) -> (B ^ A) & ~C + if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B)))) + if (match(Op1, m_Xor(m_Specific(B), m_Specific(A)))) + if (Op0->hasOneUse() || isFreeToInvert(C, C->hasOneUse())) + return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(C)); + + // (A | B) & ((~A) ^ B) -> (A & B) + // (A | B) & (B ^ (~A)) -> (A & B) + // (B | A) & ((~A) ^ B) -> (A & B) + // (B | A) & (B ^ (~A)) -> (A & B) + if (match(Op1, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) && + match(Op0, m_c_Or(m_Specific(A), m_Specific(B)))) + return BinaryOperator::CreateAnd(A, B); + + // ((~A) ^ B) & (A | B) -> (A & B) + // ((~A) ^ B) & (B | A) -> (A & B) + // (B ^ (~A)) & (A | B) -> (A & B) + // (B ^ (~A)) & (B | A) -> (A & B) + if (match(Op0, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) && + match(Op1, m_c_Or(m_Specific(A), m_Specific(B)))) + return BinaryOperator::CreateAnd(A, B); + } + + { + ICmpInst *LHS = dyn_cast<ICmpInst>(Op0); + ICmpInst *RHS = dyn_cast<ICmpInst>(Op1); + if (LHS && RHS) + if (Value *Res = foldAndOfICmps(LHS, RHS, I)) + return replaceInstUsesWith(I, Res); + + // TODO: Make this recursive; it's a little tricky because an arbitrary + // number of 'and' instructions might have to be created. + Value *X, *Y; + if (LHS && match(Op1, m_OneUse(m_And(m_Value(X), m_Value(Y))))) { + if (auto *Cmp = dyn_cast<ICmpInst>(X)) + if (Value *Res = foldAndOfICmps(LHS, Cmp, I)) + return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y)); + if (auto *Cmp = dyn_cast<ICmpInst>(Y)) + if (Value *Res = foldAndOfICmps(LHS, Cmp, I)) + return replaceInstUsesWith(I, Builder.CreateAnd(Res, X)); + } + if (RHS && match(Op0, m_OneUse(m_And(m_Value(X), m_Value(Y))))) { + if (auto *Cmp = dyn_cast<ICmpInst>(X)) + if (Value *Res = foldAndOfICmps(Cmp, RHS, I)) + return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y)); + if (auto *Cmp = dyn_cast<ICmpInst>(Y)) + if (Value *Res = foldAndOfICmps(Cmp, RHS, I)) + return replaceInstUsesWith(I, Builder.CreateAnd(Res, X)); + } + } + + if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) + if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) + if (Value *Res = foldLogicOfFCmps(LHS, RHS, true)) + return replaceInstUsesWith(I, Res); + + if (Instruction *FoldedFCmps = reassociateFCmps(I, Builder)) + return FoldedFCmps; + + if (Instruction *CastedAnd = foldCastedBitwiseLogic(I)) + return CastedAnd; + + // and(sext(A), B) / and(B, sext(A)) --> A ? B : 0, where A is i1 or <N x i1>. + Value *A; + if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) && + A->getType()->isIntOrIntVectorTy(1)) + return SelectInst::Create(A, Op1, Constant::getNullValue(I.getType())); + if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) && + A->getType()->isIntOrIntVectorTy(1)) + return SelectInst::Create(A, Op0, Constant::getNullValue(I.getType())); + + // and(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X) --> X s> Y ? X : 0. + { + Value *X, *Y; + const APInt *ShAmt; + Type *Ty = I.getType(); + if (match(&I, m_c_And(m_OneUse(m_AShr(m_NSWSub(m_Value(Y), m_Value(X)), + m_APInt(ShAmt))), + m_Deferred(X))) && + *ShAmt == Ty->getScalarSizeInBits() - 1) { + Value *NewICmpInst = Builder.CreateICmpSGT(X, Y); + return SelectInst::Create(NewICmpInst, X, ConstantInt::getNullValue(Ty)); + } + } + + return nullptr; +} + +Instruction *InstCombiner::matchBSwap(BinaryOperator &Or) { + assert(Or.getOpcode() == Instruction::Or && "bswap requires an 'or'"); + Value *Op0 = Or.getOperand(0), *Op1 = Or.getOperand(1); + + // Look through zero extends. + if (Instruction *Ext = dyn_cast<ZExtInst>(Op0)) + Op0 = Ext->getOperand(0); + + if (Instruction *Ext = dyn_cast<ZExtInst>(Op1)) + Op1 = Ext->getOperand(0); + + // (A | B) | C and A | (B | C) -> bswap if possible. + bool OrOfOrs = match(Op0, m_Or(m_Value(), m_Value())) || + match(Op1, m_Or(m_Value(), m_Value())); + + // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible. + bool OrOfShifts = match(Op0, m_LogicalShift(m_Value(), m_Value())) && + match(Op1, m_LogicalShift(m_Value(), m_Value())); + + // (A & B) | (C & D) -> bswap if possible. + bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) && + match(Op1, m_And(m_Value(), m_Value())); + + // (A << B) | (C & D) -> bswap if possible. + // The bigger pattern here is ((A & C1) << C2) | ((B >> C2) & C1), which is a + // part of the bswap idiom for specific values of C1, C2 (e.g. C1 = 16711935, + // C2 = 8 for i32). + // This pattern can occur when the operands of the 'or' are not canonicalized + // for some reason (not having only one use, for example). + bool OrOfAndAndSh = (match(Op0, m_LogicalShift(m_Value(), m_Value())) && + match(Op1, m_And(m_Value(), m_Value()))) || + (match(Op0, m_And(m_Value(), m_Value())) && + match(Op1, m_LogicalShift(m_Value(), m_Value()))); + + if (!OrOfOrs && !OrOfShifts && !OrOfAnds && !OrOfAndAndSh) + return nullptr; + + SmallVector<Instruction*, 4> Insts; + if (!recognizeBSwapOrBitReverseIdiom(&Or, true, false, Insts)) + return nullptr; + Instruction *LastInst = Insts.pop_back_val(); + LastInst->removeFromParent(); + + for (auto *Inst : Insts) + Worklist.Add(Inst); + return LastInst; +} + +/// Transform UB-safe variants of bitwise rotate to the funnel shift intrinsic. +static Instruction *matchRotate(Instruction &Or) { + // TODO: Can we reduce the code duplication between this and the related + // rotate matching code under visitSelect and visitTrunc? + unsigned Width = Or.getType()->getScalarSizeInBits(); + if (!isPowerOf2_32(Width)) + return nullptr; + + // First, find an or'd pair of opposite shifts with the same shifted operand: + // or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1) + BinaryOperator *Or0, *Or1; + if (!match(Or.getOperand(0), m_BinOp(Or0)) || + !match(Or.getOperand(1), m_BinOp(Or1))) + return nullptr; + + Value *ShVal, *ShAmt0, *ShAmt1; + if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) || + !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1))))) + return nullptr; + + BinaryOperator::BinaryOps ShiftOpcode0 = Or0->getOpcode(); + BinaryOperator::BinaryOps ShiftOpcode1 = Or1->getOpcode(); + if (ShiftOpcode0 == ShiftOpcode1) + return nullptr; + + // Match the shift amount operands for a rotate pattern. This always matches + // a subtraction on the R operand. + auto matchShiftAmount = [](Value *L, Value *R, unsigned Width) -> Value * { + // The shift amount may be masked with negation: + // (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1))) + Value *X; + unsigned Mask = Width - 1; + if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) && + match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))) + return X; + + // Similar to above, but the shift amount may be extended after masking, + // so return the extended value as the parameter for the intrinsic. + if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) && + match(R, m_And(m_Neg(m_ZExt(m_And(m_Specific(X), m_SpecificInt(Mask)))), + m_SpecificInt(Mask)))) + return L; + + return nullptr; + }; + + Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, Width); + bool SubIsOnLHS = false; + if (!ShAmt) { + ShAmt = matchShiftAmount(ShAmt1, ShAmt0, Width); + SubIsOnLHS = true; + } + if (!ShAmt) + return nullptr; + + bool IsFshl = (!SubIsOnLHS && ShiftOpcode0 == BinaryOperator::Shl) || + (SubIsOnLHS && ShiftOpcode1 == BinaryOperator::Shl); + Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr; + Function *F = Intrinsic::getDeclaration(Or.getModule(), IID, Or.getType()); + return IntrinsicInst::Create(F, { ShVal, ShVal, ShAmt }); +} + +/// If all elements of two constant vectors are 0/-1 and inverses, return true. +static bool areInverseVectorBitmasks(Constant *C1, Constant *C2) { + unsigned NumElts = C1->getType()->getVectorNumElements(); + for (unsigned i = 0; i != NumElts; ++i) { + Constant *EltC1 = C1->getAggregateElement(i); + Constant *EltC2 = C2->getAggregateElement(i); + if (!EltC1 || !EltC2) + return false; + + // One element must be all ones, and the other must be all zeros. + if (!((match(EltC1, m_Zero()) && match(EltC2, m_AllOnes())) || + (match(EltC2, m_Zero()) && match(EltC1, m_AllOnes())))) + return false; + } + return true; +} + +/// We have an expression of the form (A & C) | (B & D). If A is a scalar or +/// vector composed of all-zeros or all-ones values and is the bitwise 'not' of +/// B, it can be used as the condition operand of a select instruction. +Value *InstCombiner::getSelectCondition(Value *A, Value *B) { + // Step 1: We may have peeked through bitcasts in the caller. + // Exit immediately if we don't have (vector) integer types. + Type *Ty = A->getType(); + if (!Ty->isIntOrIntVectorTy() || !B->getType()->isIntOrIntVectorTy()) + return nullptr; + + // Step 2: We need 0 or all-1's bitmasks. + if (ComputeNumSignBits(A) != Ty->getScalarSizeInBits()) + return nullptr; + + // Step 3: If B is the 'not' value of A, we have our answer. + if (match(A, m_Not(m_Specific(B)))) { + // If these are scalars or vectors of i1, A can be used directly. + if (Ty->isIntOrIntVectorTy(1)) + return A; + return Builder.CreateTrunc(A, CmpInst::makeCmpResultType(Ty)); + } + + // If both operands are constants, see if the constants are inverse bitmasks. + Constant *AConst, *BConst; + if (match(A, m_Constant(AConst)) && match(B, m_Constant(BConst))) + if (AConst == ConstantExpr::getNot(BConst)) + return Builder.CreateZExtOrTrunc(A, CmpInst::makeCmpResultType(Ty)); + + // Look for more complex patterns. The 'not' op may be hidden behind various + // casts. Look through sexts and bitcasts to find the booleans. + Value *Cond; + Value *NotB; + if (match(A, m_SExt(m_Value(Cond))) && + Cond->getType()->isIntOrIntVectorTy(1) && + match(B, m_OneUse(m_Not(m_Value(NotB))))) { + NotB = peekThroughBitcast(NotB, true); + if (match(NotB, m_SExt(m_Specific(Cond)))) + return Cond; + } + + // All scalar (and most vector) possibilities should be handled now. + // Try more matches that only apply to non-splat constant vectors. + if (!Ty->isVectorTy()) + return nullptr; + + // If both operands are xor'd with constants using the same sexted boolean + // operand, see if the constants are inverse bitmasks. + // TODO: Use ConstantExpr::getNot()? + if (match(A, (m_Xor(m_SExt(m_Value(Cond)), m_Constant(AConst)))) && + match(B, (m_Xor(m_SExt(m_Specific(Cond)), m_Constant(BConst)))) && + Cond->getType()->isIntOrIntVectorTy(1) && + areInverseVectorBitmasks(AConst, BConst)) { + AConst = ConstantExpr::getTrunc(AConst, CmpInst::makeCmpResultType(Ty)); + return Builder.CreateXor(Cond, AConst); + } + return nullptr; +} + +/// We have an expression of the form (A & C) | (B & D). Try to simplify this +/// to "A' ? C : D", where A' is a boolean or vector of booleans. +Value *InstCombiner::matchSelectFromAndOr(Value *A, Value *C, Value *B, + Value *D) { + // The potential condition of the select may be bitcasted. In that case, look + // through its bitcast and the corresponding bitcast of the 'not' condition. + Type *OrigType = A->getType(); + A = peekThroughBitcast(A, true); + B = peekThroughBitcast(B, true); + if (Value *Cond = getSelectCondition(A, B)) { + // ((bc Cond) & C) | ((bc ~Cond) & D) --> bc (select Cond, (bc C), (bc D)) + // The bitcasts will either all exist or all not exist. The builder will + // not create unnecessary casts if the types already match. + Value *BitcastC = Builder.CreateBitCast(C, A->getType()); + Value *BitcastD = Builder.CreateBitCast(D, A->getType()); + Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastD); + return Builder.CreateBitCast(Select, OrigType); + } + + return nullptr; +} + +/// Fold (icmp)|(icmp) if possible. +Value *InstCombiner::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, + Instruction &CxtI) { + const SimplifyQuery Q = SQ.getWithInstruction(&CxtI); + + // Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2) + // if K1 and K2 are a one-bit mask. + if (Value *V = foldAndOrOfICmpsOfAndWithPow2(LHS, RHS, false, CxtI)) + return V; + + ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); + + ConstantInt *LHSC = dyn_cast<ConstantInt>(LHS->getOperand(1)); + ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS->getOperand(1)); + + // Fold (icmp ult/ule (A + C1), C3) | (icmp ult/ule (A + C2), C3) + // --> (icmp ult/ule ((A & ~(C1 ^ C2)) + max(C1, C2)), C3) + // The original condition actually refers to the following two ranges: + // [MAX_UINT-C1+1, MAX_UINT-C1+1+C3] and [MAX_UINT-C2+1, MAX_UINT-C2+1+C3] + // We can fold these two ranges if: + // 1) C1 and C2 is unsigned greater than C3. + // 2) The two ranges are separated. + // 3) C1 ^ C2 is one-bit mask. + // 4) LowRange1 ^ LowRange2 and HighRange1 ^ HighRange2 are one-bit mask. + // This implies all values in the two ranges differ by exactly one bit. + + if ((PredL == ICmpInst::ICMP_ULT || PredL == ICmpInst::ICMP_ULE) && + PredL == PredR && LHSC && RHSC && LHS->hasOneUse() && RHS->hasOneUse() && + LHSC->getType() == RHSC->getType() && + LHSC->getValue() == (RHSC->getValue())) { + + Value *LAdd = LHS->getOperand(0); + Value *RAdd = RHS->getOperand(0); + + Value *LAddOpnd, *RAddOpnd; + ConstantInt *LAddC, *RAddC; + if (match(LAdd, m_Add(m_Value(LAddOpnd), m_ConstantInt(LAddC))) && + match(RAdd, m_Add(m_Value(RAddOpnd), m_ConstantInt(RAddC))) && + LAddC->getValue().ugt(LHSC->getValue()) && + RAddC->getValue().ugt(LHSC->getValue())) { + + APInt DiffC = LAddC->getValue() ^ RAddC->getValue(); + if (LAddOpnd == RAddOpnd && DiffC.isPowerOf2()) { + ConstantInt *MaxAddC = nullptr; + if (LAddC->getValue().ult(RAddC->getValue())) + MaxAddC = RAddC; + else + MaxAddC = LAddC; + + APInt RRangeLow = -RAddC->getValue(); + APInt RRangeHigh = RRangeLow + LHSC->getValue(); + APInt LRangeLow = -LAddC->getValue(); + APInt LRangeHigh = LRangeLow + LHSC->getValue(); + APInt LowRangeDiff = RRangeLow ^ LRangeLow; + APInt HighRangeDiff = RRangeHigh ^ LRangeHigh; + APInt RangeDiff = LRangeLow.sgt(RRangeLow) ? LRangeLow - RRangeLow + : RRangeLow - LRangeLow; + + if (LowRangeDiff.isPowerOf2() && LowRangeDiff == HighRangeDiff && + RangeDiff.ugt(LHSC->getValue())) { + Value *MaskC = ConstantInt::get(LAddC->getType(), ~DiffC); + + Value *NewAnd = Builder.CreateAnd(LAddOpnd, MaskC); + Value *NewAdd = Builder.CreateAdd(NewAnd, MaxAddC); + return Builder.CreateICmp(LHS->getPredicate(), NewAdd, LHSC); + } + } + } + } + + // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B) + if (predicatesFoldable(PredL, PredR)) { + if (LHS->getOperand(0) == RHS->getOperand(1) && + LHS->getOperand(1) == RHS->getOperand(0)) + LHS->swapOperands(); + if (LHS->getOperand(0) == RHS->getOperand(0) && + LHS->getOperand(1) == RHS->getOperand(1)) { + Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); + unsigned Code = getICmpCode(LHS) | getICmpCode(RHS); + bool IsSigned = LHS->isSigned() || RHS->isSigned(); + return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder); + } + } + + // handle (roughly): + // (icmp ne (A & B), C) | (icmp ne (A & D), E) + if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder)) + return V; + + Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0); + if (LHS->hasOneUse() || RHS->hasOneUse()) { + // (icmp eq B, 0) | (icmp ult A, B) -> (icmp ule A, B-1) + // (icmp eq B, 0) | (icmp ugt B, A) -> (icmp ule A, B-1) + Value *A = nullptr, *B = nullptr; + if (PredL == ICmpInst::ICMP_EQ && LHSC && LHSC->isZero()) { + B = LHS0; + if (PredR == ICmpInst::ICMP_ULT && LHS0 == RHS->getOperand(1)) + A = RHS0; + else if (PredR == ICmpInst::ICMP_UGT && LHS0 == RHS0) + A = RHS->getOperand(1); + } + // (icmp ult A, B) | (icmp eq B, 0) -> (icmp ule A, B-1) + // (icmp ugt B, A) | (icmp eq B, 0) -> (icmp ule A, B-1) + else if (PredR == ICmpInst::ICMP_EQ && RHSC && RHSC->isZero()) { + B = RHS0; + if (PredL == ICmpInst::ICMP_ULT && RHS0 == LHS->getOperand(1)) + A = LHS0; + else if (PredL == ICmpInst::ICMP_UGT && LHS0 == RHS0) + A = LHS->getOperand(1); + } + if (A && B) + return Builder.CreateICmp( + ICmpInst::ICMP_UGE, + Builder.CreateAdd(B, ConstantInt::getSigned(B->getType(), -1)), A); + } + + // E.g. (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n + if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/true)) + return V; + + // E.g. (icmp sgt x, n) | (icmp slt x, 0) --> icmp ugt x, n + if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/true)) + return V; + + if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, false, Builder)) + return V; + + if (Value *V = foldIsPowerOf2(LHS, RHS, false /* JoinedByAnd */, Builder)) + return V; + + if (Value *X = + foldUnsignedUnderflowCheck(LHS, RHS, /*IsAnd=*/false, Q, Builder)) + return X; + if (Value *X = + foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/false, Q, Builder)) + return X; + + // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2). + if (!LHSC || !RHSC) + return nullptr; + + if (LHSC == RHSC && PredL == PredR) { + // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0) + if (PredL == ICmpInst::ICMP_NE && LHSC->isZero()) { + Value *NewOr = Builder.CreateOr(LHS0, RHS0); + return Builder.CreateICmp(PredL, NewOr, LHSC); + } + } + + // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1) + // iff C2 + CA == C1. + if (PredL == ICmpInst::ICMP_ULT && PredR == ICmpInst::ICMP_EQ) { + ConstantInt *AddC; + if (match(LHS0, m_Add(m_Specific(RHS0), m_ConstantInt(AddC)))) + if (RHSC->getValue() + AddC->getValue() == LHSC->getValue()) + return Builder.CreateICmpULE(LHS0, LHSC); + } + + // From here on, we only handle: + // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler. + if (LHS0 != RHS0) + return nullptr; + + // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere. + if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE || + PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE || + PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE || + PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE) + return nullptr; + + // We can't fold (ugt x, C) | (sgt x, C2). + if (!predicatesFoldable(PredL, PredR)) + return nullptr; + + // Ensure that the larger constant is on the RHS. + bool ShouldSwap; + if (CmpInst::isSigned(PredL) || + (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR))) + ShouldSwap = LHSC->getValue().sgt(RHSC->getValue()); + else + ShouldSwap = LHSC->getValue().ugt(RHSC->getValue()); + + if (ShouldSwap) { + std::swap(LHS, RHS); + std::swap(LHSC, RHSC); + std::swap(PredL, PredR); + } + + // At this point, we know we have two icmp instructions + // comparing a value against two constants and or'ing the result + // together. Because of the above check, we know that we only have + // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the + // icmp folding check above), that the two constants are not + // equal. + assert(LHSC != RHSC && "Compares not folded above?"); + + switch (PredL) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_EQ: + switch (PredR) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_EQ: + // Potential folds for this case should already be handled. + break; + case ICmpInst::ICMP_UGT: + // (X == 0 || X u> C) -> (X-1) u>= C + if (LHSC->isMinValue(false)) + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1, + false, false); + // (X == 13 | X u> 14) -> no change + break; + case ICmpInst::ICMP_SGT: + // (X == INT_MIN || X s> C) -> (X-(INT_MIN+1)) u>= C-INT_MIN + if (LHSC->isMinValue(true)) + return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1, + true, false); + // (X == 13 | X s> 14) -> no change + break; + } + break; + case ICmpInst::ICMP_ULT: + switch (PredR) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change + // (X u< C || X == UINT_MAX) => (X-C) u>= UINT_MAX-C + if (RHSC->isMaxValue(false)) + return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(), + false, false); + break; + case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2 + assert(!RHSC->isMaxValue(false) && "Missed icmp simplification"); + return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, + false, false); + } + break; + case ICmpInst::ICMP_SLT: + switch (PredR) { + default: + llvm_unreachable("Unknown integer condition code!"); + case ICmpInst::ICMP_EQ: + // (X s< C || X == INT_MAX) => (X-C) u>= INT_MAX-C + if (RHSC->isMaxValue(true)) + return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(), + true, false); + // (X s< 13 | X == 14) -> no change + break; + case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) u> 2 + assert(!RHSC->isMaxValue(true) && "Missed icmp simplification"); + return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true, + false); + } + break; + } + return nullptr; +} + +// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches +// here. We should standardize that construct where it is needed or choose some +// other way to ensure that commutated variants of patterns are not missed. +Instruction *InstCombiner::visitOr(BinaryOperator &I) { + if (Value *V = SimplifyOrInst(I.getOperand(0), I.getOperand(1), + SQ.getWithInstruction(&I))) + return replaceInstUsesWith(I, V); + + if (SimplifyAssociativeOrCommutative(I)) + return &I; + + if (Instruction *X = foldVectorBinop(I)) + return X; + + // See if we can simplify any instructions used by the instruction whose sole + // purpose is to compute bits we don't care about. + if (SimplifyDemandedInstructionBits(I)) + return &I; + + // Do this before using distributive laws to catch simple and/or/not patterns. + if (Instruction *Xor = foldOrToXor(I, Builder)) + return Xor; + + // (A&B)|(A&C) -> A&(B|C) etc + if (Value *V = SimplifyUsingDistributiveLaws(I)) + return replaceInstUsesWith(I, V); + + if (Value *V = SimplifyBSwap(I, Builder)) + return replaceInstUsesWith(I, V); + + if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I)) + return FoldedLogic; + + if (Instruction *BSwap = matchBSwap(I)) + return BSwap; + + if (Instruction *Rotate = matchRotate(I)) + return Rotate; + + Value *X, *Y; + const APInt *CV; + if (match(&I, m_c_Or(m_OneUse(m_Xor(m_Value(X), m_APInt(CV))), m_Value(Y))) && + !CV->isAllOnesValue() && MaskedValueIsZero(Y, *CV, 0, &I)) { + // (X ^ C) | Y -> (X | Y) ^ C iff Y & C == 0 + // The check for a 'not' op is for efficiency (if Y is known zero --> ~X). + Value *Or = Builder.CreateOr(X, Y); + return BinaryOperator::CreateXor(Or, ConstantInt::get(I.getType(), *CV)); + } + + // (A & C)|(B & D) + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + Value *A, *B, *C, *D; + if (match(Op0, m_And(m_Value(A), m_Value(C))) && + match(Op1, m_And(m_Value(B), m_Value(D)))) { + ConstantInt *C1 = dyn_cast<ConstantInt>(C); + ConstantInt *C2 = dyn_cast<ConstantInt>(D); + if (C1 && C2) { // (A & C1)|(B & C2) + Value *V1 = nullptr, *V2 = nullptr; + if ((C1->getValue() & C2->getValue()).isNullValue()) { + // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2) + // iff (C1&C2) == 0 and (N&~C1) == 0 + if (match(A, m_Or(m_Value(V1), m_Value(V2))) && + ((V1 == B && + MaskedValueIsZero(V2, ~C1->getValue(), 0, &I)) || // (V|N) + (V2 == B && + MaskedValueIsZero(V1, ~C1->getValue(), 0, &I)))) // (N|V) + return BinaryOperator::CreateAnd(A, + Builder.getInt(C1->getValue()|C2->getValue())); + // Or commutes, try both ways. + if (match(B, m_Or(m_Value(V1), m_Value(V2))) && + ((V1 == A && + MaskedValueIsZero(V2, ~C2->getValue(), 0, &I)) || // (V|N) + (V2 == A && + MaskedValueIsZero(V1, ~C2->getValue(), 0, &I)))) // (N|V) + return BinaryOperator::CreateAnd(B, + Builder.getInt(C1->getValue()|C2->getValue())); + + // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2) + // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0. + ConstantInt *C3 = nullptr, *C4 = nullptr; + if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) && + (C3->getValue() & ~C1->getValue()).isNullValue() && + match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) && + (C4->getValue() & ~C2->getValue()).isNullValue()) { + V2 = Builder.CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield"); + return BinaryOperator::CreateAnd(V2, + Builder.getInt(C1->getValue()|C2->getValue())); + } + } + + if (C1->getValue() == ~C2->getValue()) { + Value *X; + + // ((X|B)&C1)|(B&C2) -> (X&C1) | B iff C1 == ~C2 + if (match(A, m_c_Or(m_Value(X), m_Specific(B)))) + return BinaryOperator::CreateOr(Builder.CreateAnd(X, C1), B); + // (A&C2)|((X|A)&C1) -> (X&C2) | A iff C1 == ~C2 + if (match(B, m_c_Or(m_Specific(A), m_Value(X)))) + return BinaryOperator::CreateOr(Builder.CreateAnd(X, C2), A); + + // ((X^B)&C1)|(B&C2) -> (X&C1) ^ B iff C1 == ~C2 + if (match(A, m_c_Xor(m_Value(X), m_Specific(B)))) + return BinaryOperator::CreateXor(Builder.CreateAnd(X, C1), B); + // (A&C2)|((X^A)&C1) -> (X&C2) ^ A iff C1 == ~C2 + if (match(B, m_c_Xor(m_Specific(A), m_Value(X)))) + return BinaryOperator::CreateXor(Builder.CreateAnd(X, C2), A); + } + } + + // Don't try to form a select if it's unlikely that we'll get rid of at + // least one of the operands. A select is generally more expensive than the + // 'or' that it is replacing. + if (Op0->hasOneUse() || Op1->hasOneUse()) { + // (Cond & C) | (~Cond & D) -> Cond ? C : D, and commuted variants. + if (Value *V = matchSelectFromAndOr(A, C, B, D)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(A, C, D, B)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(C, A, B, D)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(C, A, D, B)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(B, D, A, C)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(B, D, C, A)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(D, B, A, C)) + return replaceInstUsesWith(I, V); + if (Value *V = matchSelectFromAndOr(D, B, C, A)) + return replaceInstUsesWith(I, V); + } + } + + // (A ^ B) | ((B ^ C) ^ A) -> (A ^ B) | C + if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) + if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A)))) + return BinaryOperator::CreateOr(Op0, C); + + // ((A ^ C) ^ B) | (B ^ A) -> (B ^ A) | C + if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B)))) + if (match(Op1, m_Xor(m_Specific(B), m_Specific(A)))) + return BinaryOperator::CreateOr(Op1, C); + + // ((B | C) & A) | B -> B | (A & C) + if (match(Op0, m_And(m_Or(m_Specific(Op1), m_Value(C)), m_Value(A)))) + return BinaryOperator::CreateOr(Op1, Builder.CreateAnd(A, C)); + + if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder)) + return DeMorgan; + + // Canonicalize xor to the RHS. + bool SwappedForXor = false; + if (match(Op0, m_Xor(m_Value(), m_Value()))) { + std::swap(Op0, Op1); + SwappedForXor = true; + } + + // A | ( A ^ B) -> A | B + // A | (~A ^ B) -> A | ~B + // (A & B) | (A ^ B) + if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) { + if (Op0 == A || Op0 == B) + return BinaryOperator::CreateOr(A, B); + + if (match(Op0, m_And(m_Specific(A), m_Specific(B))) || + match(Op0, m_And(m_Specific(B), m_Specific(A)))) + return BinaryOperator::CreateOr(A, B); + + if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) { + Value *Not = Builder.CreateNot(B, B->getName() + ".not"); + return BinaryOperator::CreateOr(Not, Op0); + } + if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) { + Value *Not = Builder.CreateNot(A, A->getName() + ".not"); + return BinaryOperator::CreateOr(Not, Op0); + } + } + + // A | ~(A | B) -> A | ~B + // A | ~(A ^ B) -> A | ~B + if (match(Op1, m_Not(m_Value(A)))) + if (BinaryOperator *B = dyn_cast<BinaryOperator>(A)) + if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) && + Op1->hasOneUse() && (B->getOpcode() == Instruction::Or || + B->getOpcode() == Instruction::Xor)) { + Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) : + B->getOperand(0); + Value *Not = Builder.CreateNot(NotOp, NotOp->getName() + ".not"); + return BinaryOperator::CreateOr(Not, Op0); + } + + if (SwappedForXor) + std::swap(Op0, Op1); + + { + ICmpInst *LHS = dyn_cast<ICmpInst>(Op0); + ICmpInst *RHS = dyn_cast<ICmpInst>(Op1); + if (LHS && RHS) + if (Value *Res = foldOrOfICmps(LHS, RHS, I)) + return replaceInstUsesWith(I, Res); + + // TODO: Make this recursive; it's a little tricky because an arbitrary + // number of 'or' instructions might have to be created. + Value *X, *Y; + if (LHS && match(Op1, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) { + if (auto *Cmp = dyn_cast<ICmpInst>(X)) + if (Value *Res = foldOrOfICmps(LHS, Cmp, I)) + return replaceInstUsesWith(I, Builder.CreateOr(Res, Y)); + if (auto *Cmp = dyn_cast<ICmpInst>(Y)) + if (Value *Res = foldOrOfICmps(LHS, Cmp, I)) + return replaceInstUsesWith(I, Builder.CreateOr(Res, X)); + } + if (RHS && match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) { + if (auto *Cmp = dyn_cast<ICmpInst>(X)) + if (Value *Res = foldOrOfICmps(Cmp, RHS, I)) + return replaceInstUsesWith(I, Builder.CreateOr(Res, Y)); + if (auto *Cmp = dyn_cast<ICmpInst>(Y)) + if (Value *Res = foldOrOfICmps(Cmp, RHS, I)) + return replaceInstUsesWith(I, Builder.CreateOr(Res, X)); + } + } + + if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) + if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) + if (Value *Res = foldLogicOfFCmps(LHS, RHS, false)) + return replaceInstUsesWith(I, Res); + + if (Instruction *FoldedFCmps = reassociateFCmps(I, Builder)) + return FoldedFCmps; + + if (Instruction *CastedOr = foldCastedBitwiseLogic(I)) + return CastedOr; + + // or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or <N x i1>. + if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) && + A->getType()->isIntOrIntVectorTy(1)) + return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1); + if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) && + A->getType()->isIntOrIntVectorTy(1)) + return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0); + + // Note: If we've gotten to the point of visiting the outer OR, then the + // inner one couldn't be simplified. If it was a constant, then it won't + // be simplified by a later pass either, so we try swapping the inner/outer + // ORs in the hopes that we'll be able to simplify it this way. + // (X|C) | V --> (X|V) | C + ConstantInt *CI; + if (Op0->hasOneUse() && !isa<ConstantInt>(Op1) && + match(Op0, m_Or(m_Value(A), m_ConstantInt(CI)))) { + Value *Inner = Builder.CreateOr(A, Op1); + Inner->takeName(Op0); + return BinaryOperator::CreateOr(Inner, CI); + } + + // Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D)) + // Since this OR statement hasn't been optimized further yet, we hope + // that this transformation will allow the new ORs to be optimized. + { + Value *X = nullptr, *Y = nullptr; + if (Op0->hasOneUse() && Op1->hasOneUse() && + match(Op0, m_Select(m_Value(X), m_Value(A), m_Value(B))) && + match(Op1, m_Select(m_Value(Y), m_Value(C), m_Value(D))) && X == Y) { + Value *orTrue = Builder.CreateOr(A, C); + Value *orFalse = Builder.CreateOr(B, D); + return SelectInst::Create(X, orTrue, orFalse); + } + } + + // or(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X) --> X s> Y ? -1 : X. + { + Value *X, *Y; + const APInt *ShAmt; + Type *Ty = I.getType(); + if (match(&I, m_c_Or(m_OneUse(m_AShr(m_NSWSub(m_Value(Y), m_Value(X)), + m_APInt(ShAmt))), + m_Deferred(X))) && + *ShAmt == Ty->getScalarSizeInBits() - 1) { + Value *NewICmpInst = Builder.CreateICmpSGT(X, Y); + return SelectInst::Create(NewICmpInst, ConstantInt::getAllOnesValue(Ty), + X); + } + } + + if (Instruction *V = + canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I)) + return V; + + return nullptr; +} + +/// A ^ B can be specified using other logic ops in a variety of patterns. We +/// can fold these early and efficiently by morphing an existing instruction. +static Instruction *foldXorToXor(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + assert(I.getOpcode() == Instruction::Xor); + Value *Op0 = I.getOperand(0); + Value *Op1 = I.getOperand(1); + Value *A, *B; + + // There are 4 commuted variants for each of the basic patterns. + + // (A & B) ^ (A | B) -> A ^ B + // (A & B) ^ (B | A) -> A ^ B + // (A | B) ^ (A & B) -> A ^ B + // (A | B) ^ (B & A) -> A ^ B + if (match(&I, m_c_Xor(m_And(m_Value(A), m_Value(B)), + m_c_Or(m_Deferred(A), m_Deferred(B))))) { + I.setOperand(0, A); + I.setOperand(1, B); + return &I; + } + + // (A | ~B) ^ (~A | B) -> A ^ B + // (~B | A) ^ (~A | B) -> A ^ B + // (~A | B) ^ (A | ~B) -> A ^ B + // (B | ~A) ^ (A | ~B) -> A ^ B + if (match(&I, m_Xor(m_c_Or(m_Value(A), m_Not(m_Value(B))), + m_c_Or(m_Not(m_Deferred(A)), m_Deferred(B))))) { + I.setOperand(0, A); + I.setOperand(1, B); + return &I; + } + + // (A & ~B) ^ (~A & B) -> A ^ B + // (~B & A) ^ (~A & B) -> A ^ B + // (~A & B) ^ (A & ~B) -> A ^ B + // (B & ~A) ^ (A & ~B) -> A ^ B + if (match(&I, m_Xor(m_c_And(m_Value(A), m_Not(m_Value(B))), + m_c_And(m_Not(m_Deferred(A)), m_Deferred(B))))) { + I.setOperand(0, A); + I.setOperand(1, B); + return &I; + } + + // For the remaining cases we need to get rid of one of the operands. + if (!Op0->hasOneUse() && !Op1->hasOneUse()) + return nullptr; + + // (A | B) ^ ~(A & B) -> ~(A ^ B) + // (A | B) ^ ~(B & A) -> ~(A ^ B) + // (A & B) ^ ~(A | B) -> ~(A ^ B) + // (A & B) ^ ~(B | A) -> ~(A ^ B) + // Complexity sorting ensures the not will be on the right side. + if ((match(Op0, m_Or(m_Value(A), m_Value(B))) && + match(Op1, m_Not(m_c_And(m_Specific(A), m_Specific(B))))) || + (match(Op0, m_And(m_Value(A), m_Value(B))) && + match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))) + return BinaryOperator::CreateNot(Builder.CreateXor(A, B)); + + return nullptr; +} + +Value *InstCombiner::foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS, + BinaryOperator &I) { + assert(I.getOpcode() == Instruction::Xor && I.getOperand(0) == LHS && + I.getOperand(1) == RHS && "Should be 'xor' with these operands"); + + if (predicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) { + if (LHS->getOperand(0) == RHS->getOperand(1) && + LHS->getOperand(1) == RHS->getOperand(0)) + LHS->swapOperands(); + if (LHS->getOperand(0) == RHS->getOperand(0) && + LHS->getOperand(1) == RHS->getOperand(1)) { + // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B) + Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); + unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS); + bool IsSigned = LHS->isSigned() || RHS->isSigned(); + return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder); + } + } + + // TODO: This can be generalized to compares of non-signbits using + // decomposeBitTestICmp(). It could be enhanced more by using (something like) + // foldLogOpOfMaskedICmps(). + ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); + Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); + Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); + if ((LHS->hasOneUse() || RHS->hasOneUse()) && + LHS0->getType() == RHS0->getType() && + LHS0->getType()->isIntOrIntVectorTy()) { + // (X > -1) ^ (Y > -1) --> (X ^ Y) < 0 + // (X < 0) ^ (Y < 0) --> (X ^ Y) < 0 + if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) && + PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes())) || + (PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) && + PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero()))) { + Value *Zero = ConstantInt::getNullValue(LHS0->getType()); + return Builder.CreateICmpSLT(Builder.CreateXor(LHS0, RHS0), Zero); + } + // (X > -1) ^ (Y < 0) --> (X ^ Y) > -1 + // (X < 0) ^ (Y > -1) --> (X ^ Y) > -1 + if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) && + PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero())) || + (PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) && + PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes()))) { + Value *MinusOne = ConstantInt::getAllOnesValue(LHS0->getType()); + return Builder.CreateICmpSGT(Builder.CreateXor(LHS0, RHS0), MinusOne); + } + } + + // Instead of trying to imitate the folds for and/or, decompose this 'xor' + // into those logic ops. That is, try to turn this into an and-of-icmps + // because we have many folds for that pattern. + // + // This is based on a truth table definition of xor: + // X ^ Y --> (X | Y) & !(X & Y) + if (Value *OrICmp = SimplifyBinOp(Instruction::Or, LHS, RHS, SQ)) { + // TODO: If OrICmp is true, then the definition of xor simplifies to !(X&Y). + // TODO: If OrICmp is false, the whole thing is false (InstSimplify?). + if (Value *AndICmp = SimplifyBinOp(Instruction::And, LHS, RHS, SQ)) { + // TODO: Independently handle cases where the 'and' side is a constant. + ICmpInst *X = nullptr, *Y = nullptr; + if (OrICmp == LHS && AndICmp == RHS) { + // (LHS | RHS) & !(LHS & RHS) --> LHS & !RHS --> X & !Y + X = LHS; + Y = RHS; + } + if (OrICmp == RHS && AndICmp == LHS) { + // !(LHS & RHS) & (LHS | RHS) --> !LHS & RHS --> !Y & X + X = RHS; + Y = LHS; + } + if (X && Y && (Y->hasOneUse() || canFreelyInvertAllUsersOf(Y, &I))) { + // Invert the predicate of 'Y', thus inverting its output. + Y->setPredicate(Y->getInversePredicate()); + // So, are there other uses of Y? + if (!Y->hasOneUse()) { + // We need to adapt other uses of Y though. Get a value that matches + // the original value of Y before inversion. While this increases + // immediate instruction count, we have just ensured that all the + // users are freely-invertible, so that 'not' *will* get folded away. + BuilderTy::InsertPointGuard Guard(Builder); + // Set insertion point to right after the Y. + Builder.SetInsertPoint(Y->getParent(), ++(Y->getIterator())); + Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not"); + // Replace all uses of Y (excluding the one in NotY!) with NotY. + Y->replaceUsesWithIf(NotY, + [NotY](Use &U) { return U.getUser() != NotY; }); + } + // All done. + return Builder.CreateAnd(LHS, RHS); + } + } + } + + return nullptr; +} + +/// If we have a masked merge, in the canonical form of: +/// (assuming that A only has one use.) +/// | A | |B| +/// ((x ^ y) & M) ^ y +/// | D | +/// * If M is inverted: +/// | D | +/// ((x ^ y) & ~M) ^ y +/// We can canonicalize by swapping the final xor operand +/// to eliminate the 'not' of the mask. +/// ((x ^ y) & M) ^ x +/// * If M is a constant, and D has one use, we transform to 'and' / 'or' ops +/// because that shortens the dependency chain and improves analysis: +/// (x & M) | (y & ~M) +static Instruction *visitMaskedMerge(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + Value *B, *X, *D; + Value *M; + if (!match(&I, m_c_Xor(m_Value(B), + m_OneUse(m_c_And( + m_CombineAnd(m_c_Xor(m_Deferred(B), m_Value(X)), + m_Value(D)), + m_Value(M)))))) + return nullptr; + + Value *NotM; + if (match(M, m_Not(m_Value(NotM)))) { + // De-invert the mask and swap the value in B part. + Value *NewA = Builder.CreateAnd(D, NotM); + return BinaryOperator::CreateXor(NewA, X); + } + + Constant *C; + if (D->hasOneUse() && match(M, m_Constant(C))) { + // Unfold. + Value *LHS = Builder.CreateAnd(X, C); + Value *NotC = Builder.CreateNot(C); + Value *RHS = Builder.CreateAnd(B, NotC); + return BinaryOperator::CreateOr(LHS, RHS); + } + + return nullptr; +} + +// Transform +// ~(x ^ y) +// into: +// (~x) ^ y +// or into +// x ^ (~y) +static Instruction *sinkNotIntoXor(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + Value *X, *Y; + // FIXME: one-use check is not needed in general, but currently we are unable + // to fold 'not' into 'icmp', if that 'icmp' has multiple uses. (D35182) + if (!match(&I, m_Not(m_OneUse(m_Xor(m_Value(X), m_Value(Y)))))) + return nullptr; + + // We only want to do the transform if it is free to do. + if (isFreeToInvert(X, X->hasOneUse())) { + // Ok, good. + } else if (isFreeToInvert(Y, Y->hasOneUse())) { + std::swap(X, Y); + } else + return nullptr; + + Value *NotX = Builder.CreateNot(X, X->getName() + ".not"); + return BinaryOperator::CreateXor(NotX, Y, I.getName() + ".demorgan"); +} + +// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches +// here. We should standardize that construct where it is needed or choose some +// other way to ensure that commutated variants of patterns are not missed. +Instruction *InstCombiner::visitXor(BinaryOperator &I) { + if (Value *V = SimplifyXorInst(I.getOperand(0), I.getOperand(1), + SQ.getWithInstruction(&I))) + return replaceInstUsesWith(I, V); + + if (SimplifyAssociativeOrCommutative(I)) + return &I; + + if (Instruction *X = foldVectorBinop(I)) + return X; + + if (Instruction *NewXor = foldXorToXor(I, Builder)) + return NewXor; + + // (A&B)^(A&C) -> A&(B^C) etc + if (Value *V = SimplifyUsingDistributiveLaws(I)) + return replaceInstUsesWith(I, V); + + // See if we can simplify any instructions used by the instruction whose sole + // purpose is to compute bits we don't care about. + if (SimplifyDemandedInstructionBits(I)) + return &I; + + if (Value *V = SimplifyBSwap(I, Builder)) + return replaceInstUsesWith(I, V); + + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + // Fold (X & M) ^ (Y & ~M) -> (X & M) | (Y & ~M) + // This it a special case in haveNoCommonBitsSet, but the computeKnownBits + // calls in there are unnecessary as SimplifyDemandedInstructionBits should + // have already taken care of those cases. + Value *M; + if (match(&I, m_c_Xor(m_c_And(m_Not(m_Value(M)), m_Value()), + m_c_And(m_Deferred(M), m_Value())))) + return BinaryOperator::CreateOr(Op0, Op1); + + // Apply DeMorgan's Law for 'nand' / 'nor' logic with an inverted operand. + Value *X, *Y; + + // We must eliminate the and/or (one-use) for these transforms to not increase + // the instruction count. + // ~(~X & Y) --> (X | ~Y) + // ~(Y & ~X) --> (X | ~Y) + if (match(&I, m_Not(m_OneUse(m_c_And(m_Not(m_Value(X)), m_Value(Y)))))) { + Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not"); + return BinaryOperator::CreateOr(X, NotY); + } + // ~(~X | Y) --> (X & ~Y) + // ~(Y | ~X) --> (X & ~Y) + if (match(&I, m_Not(m_OneUse(m_c_Or(m_Not(m_Value(X)), m_Value(Y)))))) { + Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not"); + return BinaryOperator::CreateAnd(X, NotY); + } + + if (Instruction *Xor = visitMaskedMerge(I, Builder)) + return Xor; + + // Is this a 'not' (~) fed by a binary operator? + BinaryOperator *NotVal; + if (match(&I, m_Not(m_BinOp(NotVal)))) { + if (NotVal->getOpcode() == Instruction::And || + NotVal->getOpcode() == Instruction::Or) { + // Apply DeMorgan's Law when inverts are free: + // ~(X & Y) --> (~X | ~Y) + // ~(X | Y) --> (~X & ~Y) + if (isFreeToInvert(NotVal->getOperand(0), + NotVal->getOperand(0)->hasOneUse()) && + isFreeToInvert(NotVal->getOperand(1), + NotVal->getOperand(1)->hasOneUse())) { + Value *NotX = Builder.CreateNot(NotVal->getOperand(0), "notlhs"); + Value *NotY = Builder.CreateNot(NotVal->getOperand(1), "notrhs"); + if (NotVal->getOpcode() == Instruction::And) + return BinaryOperator::CreateOr(NotX, NotY); + return BinaryOperator::CreateAnd(NotX, NotY); + } + } + + // ~(X - Y) --> ~X + Y + if (match(NotVal, m_Sub(m_Value(X), m_Value(Y)))) + if (isa<Constant>(X) || NotVal->hasOneUse()) + return BinaryOperator::CreateAdd(Builder.CreateNot(X), Y); + + // ~(~X >>s Y) --> (X >>s Y) + if (match(NotVal, m_AShr(m_Not(m_Value(X)), m_Value(Y)))) + return BinaryOperator::CreateAShr(X, Y); + + // If we are inverting a right-shifted constant, we may be able to eliminate + // the 'not' by inverting the constant and using the opposite shift type. + // Canonicalization rules ensure that only a negative constant uses 'ashr', + // but we must check that in case that transform has not fired yet. + + // ~(C >>s Y) --> ~C >>u Y (when inverting the replicated sign bits) + Constant *C; + if (match(NotVal, m_AShr(m_Constant(C), m_Value(Y))) && + match(C, m_Negative())) + return BinaryOperator::CreateLShr(ConstantExpr::getNot(C), Y); + + // ~(C >>u Y) --> ~C >>s Y (when inverting the replicated sign bits) + if (match(NotVal, m_LShr(m_Constant(C), m_Value(Y))) && + match(C, m_NonNegative())) + return BinaryOperator::CreateAShr(ConstantExpr::getNot(C), Y); + + // ~(X + C) --> -(C + 1) - X + if (match(Op0, m_Add(m_Value(X), m_Constant(C)))) + return BinaryOperator::CreateSub(ConstantExpr::getNeg(AddOne(C)), X); + } + + // Use DeMorgan and reassociation to eliminate a 'not' op. + Constant *C1; + if (match(Op1, m_Constant(C1))) { + Constant *C2; + if (match(Op0, m_OneUse(m_Or(m_Not(m_Value(X)), m_Constant(C2))))) { + // (~X | C2) ^ C1 --> ((X & ~C2) ^ -1) ^ C1 --> (X & ~C2) ^ ~C1 + Value *And = Builder.CreateAnd(X, ConstantExpr::getNot(C2)); + return BinaryOperator::CreateXor(And, ConstantExpr::getNot(C1)); + } + if (match(Op0, m_OneUse(m_And(m_Not(m_Value(X)), m_Constant(C2))))) { + // (~X & C2) ^ C1 --> ((X | ~C2) ^ -1) ^ C1 --> (X | ~C2) ^ ~C1 + Value *Or = Builder.CreateOr(X, ConstantExpr::getNot(C2)); + return BinaryOperator::CreateXor(Or, ConstantExpr::getNot(C1)); + } + } + + // not (cmp A, B) = !cmp A, B + CmpInst::Predicate Pred; + if (match(&I, m_Not(m_OneUse(m_Cmp(Pred, m_Value(), m_Value()))))) { + cast<CmpInst>(Op0)->setPredicate(CmpInst::getInversePredicate(Pred)); + return replaceInstUsesWith(I, Op0); + } + + { + const APInt *RHSC; + if (match(Op1, m_APInt(RHSC))) { + Value *X; + const APInt *C; + if (RHSC->isSignMask() && match(Op0, m_Sub(m_APInt(C), m_Value(X)))) { + // (C - X) ^ signmask -> (C + signmask - X) + Constant *NewC = ConstantInt::get(I.getType(), *C + *RHSC); + return BinaryOperator::CreateSub(NewC, X); + } + if (RHSC->isSignMask() && match(Op0, m_Add(m_Value(X), m_APInt(C)))) { + // (X + C) ^ signmask -> (X + C + signmask) + Constant *NewC = ConstantInt::get(I.getType(), *C + *RHSC); + return BinaryOperator::CreateAdd(X, NewC); + } + + // (X|C1)^C2 -> X^(C1^C2) iff X&~C1 == 0 + if (match(Op0, m_Or(m_Value(X), m_APInt(C))) && + MaskedValueIsZero(X, *C, 0, &I)) { + Constant *NewC = ConstantInt::get(I.getType(), *C ^ *RHSC); + Worklist.Add(cast<Instruction>(Op0)); + I.setOperand(0, X); + I.setOperand(1, NewC); + return &I; + } + } + } + + if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1)) { + if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { + if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) { + if (Op0I->getOpcode() == Instruction::LShr) { + // ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3) + // E1 = "X ^ C1" + BinaryOperator *E1; + ConstantInt *C1; + if (Op0I->hasOneUse() && + (E1 = dyn_cast<BinaryOperator>(Op0I->getOperand(0))) && + E1->getOpcode() == Instruction::Xor && + (C1 = dyn_cast<ConstantInt>(E1->getOperand(1)))) { + // fold (C1 >> C2) ^ C3 + ConstantInt *C2 = Op0CI, *C3 = RHSC; + APInt FoldConst = C1->getValue().lshr(C2->getValue()); + FoldConst ^= C3->getValue(); + // Prepare the two operands. + Value *Opnd0 = Builder.CreateLShr(E1->getOperand(0), C2); + Opnd0->takeName(Op0I); + cast<Instruction>(Opnd0)->setDebugLoc(I.getDebugLoc()); + Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst); + + return BinaryOperator::CreateXor(Opnd0, FoldVal); + } + } + } + } + } + + if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I)) + return FoldedLogic; + + // Y ^ (X | Y) --> X & ~Y + // Y ^ (Y | X) --> X & ~Y + if (match(Op1, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op0))))) + return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op0)); + // (X | Y) ^ Y --> X & ~Y + // (Y | X) ^ Y --> X & ~Y + if (match(Op0, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op1))))) + return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op1)); + + // Y ^ (X & Y) --> ~X & Y + // Y ^ (Y & X) --> ~X & Y + if (match(Op1, m_OneUse(m_c_And(m_Value(X), m_Specific(Op0))))) + return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(X)); + // (X & Y) ^ Y --> ~X & Y + // (Y & X) ^ Y --> ~X & Y + // Canonical form is (X & C) ^ C; don't touch that. + // TODO: A 'not' op is better for analysis and codegen, but demanded bits must + // be fixed to prefer that (otherwise we get infinite looping). + if (!match(Op1, m_Constant()) && + match(Op0, m_OneUse(m_c_And(m_Value(X), m_Specific(Op1))))) + return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(X)); + + Value *A, *B, *C; + // (A ^ B) ^ (A | C) --> (~A & C) ^ B -- There are 4 commuted variants. + if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_Value(A), m_Value(B))), + m_OneUse(m_c_Or(m_Deferred(A), m_Value(C)))))) + return BinaryOperator::CreateXor( + Builder.CreateAnd(Builder.CreateNot(A), C), B); + + // (A ^ B) ^ (B | C) --> (~B & C) ^ A -- There are 4 commuted variants. + if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_Value(A), m_Value(B))), + m_OneUse(m_c_Or(m_Deferred(B), m_Value(C)))))) + return BinaryOperator::CreateXor( + Builder.CreateAnd(Builder.CreateNot(B), C), A); + + // (A & B) ^ (A ^ B) -> (A | B) + if (match(Op0, m_And(m_Value(A), m_Value(B))) && + match(Op1, m_c_Xor(m_Specific(A), m_Specific(B)))) + return BinaryOperator::CreateOr(A, B); + // (A ^ B) ^ (A & B) -> (A | B) + if (match(Op0, m_Xor(m_Value(A), m_Value(B))) && + match(Op1, m_c_And(m_Specific(A), m_Specific(B)))) + return BinaryOperator::CreateOr(A, B); + + // (A & ~B) ^ ~A -> ~(A & B) + // (~B & A) ^ ~A -> ~(A & B) + if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && + match(Op1, m_Not(m_Specific(A)))) + return BinaryOperator::CreateNot(Builder.CreateAnd(A, B)); + + if (auto *LHS = dyn_cast<ICmpInst>(I.getOperand(0))) + if (auto *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) + if (Value *V = foldXorOfICmps(LHS, RHS, I)) + return replaceInstUsesWith(I, V); + + if (Instruction *CastedXor = foldCastedBitwiseLogic(I)) + return CastedXor; + + // Canonicalize a shifty way to code absolute value to the common pattern. + // There are 4 potential commuted variants. Move the 'ashr' candidate to Op1. + // We're relying on the fact that we only do this transform when the shift has + // exactly 2 uses and the add has exactly 1 use (otherwise, we might increase + // instructions). + if (Op0->hasNUses(2)) + std::swap(Op0, Op1); + + const APInt *ShAmt; + Type *Ty = I.getType(); + if (match(Op1, m_AShr(m_Value(A), m_APInt(ShAmt))) && + Op1->hasNUses(2) && *ShAmt == Ty->getScalarSizeInBits() - 1 && + match(Op0, m_OneUse(m_c_Add(m_Specific(A), m_Specific(Op1))))) { + // B = ashr i32 A, 31 ; smear the sign bit + // xor (add A, B), B ; add -1 and flip bits if negative + // --> (A < 0) ? -A : A + Value *Cmp = Builder.CreateICmpSLT(A, ConstantInt::getNullValue(Ty)); + // Copy the nuw/nsw flags from the add to the negate. + auto *Add = cast<BinaryOperator>(Op0); + Value *Neg = Builder.CreateNeg(A, "", Add->hasNoUnsignedWrap(), + Add->hasNoSignedWrap()); + return SelectInst::Create(Cmp, Neg, A); + } + + // Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max: + // + // %notx = xor i32 %x, -1 + // %cmp1 = icmp sgt i32 %notx, %y + // %smax = select i1 %cmp1, i32 %notx, i32 %y + // %res = xor i32 %smax, -1 + // => + // %noty = xor i32 %y, -1 + // %cmp2 = icmp slt %x, %noty + // %res = select i1 %cmp2, i32 %x, i32 %noty + // + // Same is applicable for smin/umax/umin. + if (match(Op1, m_AllOnes()) && Op0->hasOneUse()) { + Value *LHS, *RHS; + SelectPatternFlavor SPF = matchSelectPattern(Op0, LHS, RHS).Flavor; + if (SelectPatternResult::isMinOrMax(SPF)) { + // It's possible we get here before the not has been simplified, so make + // sure the input to the not isn't freely invertible. + if (match(LHS, m_Not(m_Value(X))) && !isFreeToInvert(X, X->hasOneUse())) { + Value *NotY = Builder.CreateNot(RHS); + return SelectInst::Create( + Builder.CreateICmp(getInverseMinMaxPred(SPF), X, NotY), X, NotY); + } + + // It's possible we get here before the not has been simplified, so make + // sure the input to the not isn't freely invertible. + if (match(RHS, m_Not(m_Value(Y))) && !isFreeToInvert(Y, Y->hasOneUse())) { + Value *NotX = Builder.CreateNot(LHS); + return SelectInst::Create( + Builder.CreateICmp(getInverseMinMaxPred(SPF), NotX, Y), NotX, Y); + } + + // If both sides are freely invertible, then we can get rid of the xor + // completely. + if (isFreeToInvert(LHS, !LHS->hasNUsesOrMore(3)) && + isFreeToInvert(RHS, !RHS->hasNUsesOrMore(3))) { + Value *NotLHS = Builder.CreateNot(LHS); + Value *NotRHS = Builder.CreateNot(RHS); + return SelectInst::Create( + Builder.CreateICmp(getInverseMinMaxPred(SPF), NotLHS, NotRHS), + NotLHS, NotRHS); + } + } + } + + if (Instruction *NewXor = sinkNotIntoXor(I, Builder)) + return NewXor; + + return nullptr; +} |