//===- 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/IR/ConstantRange.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/PatternMatch.h" #include "llvm/Transforms/InstCombine/InstCombiner.h" #include "llvm/Transforms/Utils/Local.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(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); } /// 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 *InstCombinerImpl::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) { const APInt *ConstA = nullptr, *ConstB = nullptr, *ConstC = nullptr; match(A, m_APInt(ConstA)); match(B, m_APInt(ConstB)); match(C, m_APInt(ConstC)); bool IsEq = (Pred == ICmpInst::ICMP_EQ); bool IsAPow2 = ConstA && ConstA->isPowerOf2(); bool IsBPow2 = ConstB && ConstB->isPowerOf2(); unsigned MaskVal = 0; if (ConstC && ConstC->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 (ConstA && ConstC && ConstC->isSubsetOf(*ConstA)) { 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 (ConstB && ConstC && ConstC->isSubsetOf(*ConstB)) { 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> getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C, Value *&D, Value *&E, ICmpInst *LHS, ICmpInst *RHS, ICmpInst::Predicate &PredL, ICmpInst::Predicate &PredR) { // Don't allow pointers. Splat vectors are fine. if (!LHS->getOperand(0)->getType()->isIntOrIntVectorTy() || !RHS->getOperand(0)->getType()->isIntOrIntVectorTy()) 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; } assert(Ok && "Failed to find AND on the right side of the RHS icmp."); } 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::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, 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, *CCst, *DCst, *ECst; if (!match(B, m_ConstantInt(BCst)) || !match(C, m_ConstantInt(CCst)) || !match(D, m_ConstantInt(DCst)) || !match(E, m_ConstantInt(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(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, 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, InstCombiner::BuilderTy &Builder) { Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr; ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); Optional> 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. const APInt *ConstB, *ConstD; if (!match(B, m_APInt(ConstB)) || !match(D, m_APInt(ConstD))) 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 = *ConstB & *ConstD; if (NewMask == *ConstB) return LHS; else if (NewMask == *ConstD) 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 = *ConstB | *ConstD; if (NewMask == *ConstB) return LHS; else if (NewMask == *ConstD) 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. const APInt *OldConstC, *OldConstE; if (!match(C, m_APInt(OldConstC)) || !match(E, m_APInt(OldConstE))) return nullptr; const APInt ConstC = PredL != NewCC ? *ConstB ^ *OldConstC : *OldConstC; const APInt ConstE = PredR != NewCC ? *ConstD ^ *OldConstE : *OldConstE; // If there is a conflict, we should actually return a false for the // whole construct. if (((*ConstB & *ConstD) & (ConstC ^ ConstE)).getBoolValue()) return ConstantInt::get(LHS->getType(), !IsAnd); Value *NewOr1 = Builder.CreateOr(B, D); Value *NewAnd = Builder.CreateAnd(A, NewOr1); Constant *NewOr2 = ConstantInt::get(A->getType(), ConstC | ConstE); 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 *InstCombinerImpl::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(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)); } 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 *InstCombinerImpl::foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI, bool IsAnd, bool IsLogical) { CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_NE : CmpInst::ICMP_EQ; if (LHS->getPredicate() != Pred || RHS->getPredicate() != Pred) return nullptr; if (!match(LHS->getOperand(1), m_Zero()) || !match(RHS->getOperand(1), m_Zero())) return nullptr; Value *L1, *L2, *R1, *R2; if (match(LHS->getOperand(0), m_And(m_Value(L1), m_Value(L2))) && match(RHS->getOperand(0), m_And(m_Value(R1), m_Value(R2)))) { if (L1 == R2 || L2 == R2) std::swap(R1, R2); if (L2 == R1) std::swap(L1, L2); if (L1 == R1 && isKnownToBeAPowerOfTwo(L2, false, 0, CxtI) && isKnownToBeAPowerOfTwo(R2, false, 0, CxtI)) { // If this is a logical and/or, then we must prevent propagation of a // poison value from the RHS by inserting freeze. if (IsLogical) R2 = Builder.CreateFreeze(R2); Value *Mask = Builder.CreateOr(L2, R2); Value *Masked = Builder.CreateAnd(L1, Mask); auto NewPred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::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.isZero() && "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(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(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())) { 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; // 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; } struct IntPart { Value *From; unsigned StartBit; unsigned NumBits; }; /// Match an extraction of bits from an integer. static Optional matchIntPart(Value *V) { Value *X; if (!match(V, m_OneUse(m_Trunc(m_Value(X))))) return None; unsigned NumOriginalBits = X->getType()->getScalarSizeInBits(); unsigned NumExtractedBits = V->getType()->getScalarSizeInBits(); Value *Y; const APInt *Shift; // For a trunc(lshr Y, Shift) pattern, make sure we're only extracting bits // from Y, not any shifted-in zeroes. if (match(X, m_OneUse(m_LShr(m_Value(Y), m_APInt(Shift)))) && Shift->ule(NumOriginalBits - NumExtractedBits)) return {{Y, (unsigned)Shift->getZExtValue(), NumExtractedBits}}; return {{X, 0, NumExtractedBits}}; } /// Materialize an extraction of bits from an integer in IR. static Value *extractIntPart(const IntPart &P, IRBuilderBase &Builder) { Value *V = P.From; if (P.StartBit) V = Builder.CreateLShr(V, P.StartBit); Type *TruncTy = V->getType()->getWithNewBitWidth(P.NumBits); if (TruncTy != V->getType()) V = Builder.CreateTrunc(V, TruncTy); return V; } /// (icmp eq X0, Y0) & (icmp eq X1, Y1) -> icmp eq X01, Y01 /// (icmp ne X0, Y0) | (icmp ne X1, Y1) -> icmp ne X01, Y01 /// where X0, X1 and Y0, Y1 are adjacent parts extracted from an integer. Value *InstCombinerImpl::foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1, bool IsAnd) { if (!Cmp0->hasOneUse() || !Cmp1->hasOneUse()) return nullptr; CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::ICMP_NE; if (Cmp0->getPredicate() != Pred || Cmp1->getPredicate() != Pred) return nullptr; Optional L0 = matchIntPart(Cmp0->getOperand(0)); Optional R0 = matchIntPart(Cmp0->getOperand(1)); Optional L1 = matchIntPart(Cmp1->getOperand(0)); Optional R1 = matchIntPart(Cmp1->getOperand(1)); if (!L0 || !R0 || !L1 || !R1) return nullptr; // Make sure the LHS/RHS compare a part of the same value, possibly after // an operand swap. if (L0->From != L1->From || R0->From != R1->From) { if (L0->From != R1->From || R0->From != L1->From) return nullptr; std::swap(L1, R1); } // Make sure the extracted parts are adjacent, canonicalizing to L0/R0 being // the low part and L1/R1 being the high part. if (L0->StartBit + L0->NumBits != L1->StartBit || R0->StartBit + R0->NumBits != R1->StartBit) { if (L1->StartBit + L1->NumBits != L0->StartBit || R1->StartBit + R1->NumBits != R0->StartBit) return nullptr; std::swap(L0, L1); std::swap(R0, R1); } // We can simplify to a comparison of these larger parts of the integers. IntPart L = {L0->From, L0->StartBit, L0->NumBits + L1->NumBits}; IntPart R = {R0->From, R0->StartBit, R0->NumBits + R1->NumBits}; Value *LValue = extractIntPart(L, Builder); Value *RValue = extractIntPart(R, Builder); return Builder.CreateICmp(Pred, LValue, RValue); } /// Reduce logic-of-compares with equality to a constant by substituting a /// common operand with the constant. Callers are expected to call this with /// Cmp0/Cmp1 switched to handle logic op commutativity. static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1, BinaryOperator &Logic, InstCombiner::BuilderTy &Builder, const SimplifyQuery &Q) { bool IsAnd = Logic.getOpcode() == Instruction::And; assert((IsAnd || Logic.getOpcode() == Instruction::Or) && "Wrong logic op"); // Match an equality compare with a non-poison constant as Cmp0. // Also, give up if the compare can be constant-folded to avoid looping. ICmpInst::Predicate Pred0; Value *X; Constant *C; if (!match(Cmp0, m_ICmp(Pred0, m_Value(X), m_Constant(C))) || !isGuaranteedNotToBeUndefOrPoison(C) || isa(X)) return nullptr; if ((IsAnd && Pred0 != ICmpInst::ICMP_EQ) || (!IsAnd && Pred0 != ICmpInst::ICMP_NE)) return nullptr; // The other compare must include a common operand (X). Canonicalize the // common operand as operand 1 (Pred1 is swapped if the common operand was // operand 0). Value *Y; ICmpInst::Predicate Pred1; if (!match(Cmp1, m_c_ICmp(Pred1, m_Value(Y), m_Deferred(X)))) return nullptr; // Replace variable with constant value equivalence to remove a variable use: // (X == C) && (Y Pred1 X) --> (X == C) && (Y Pred1 C) // (X != C) || (Y Pred1 X) --> (X != C) || (Y Pred1 C) // Can think of the 'or' substitution with the 'and' bool equivalent: // A || B --> A || (!A && B) Value *SubstituteCmp = SimplifyICmpInst(Pred1, Y, C, Q); if (!SubstituteCmp) { // If we need to create a new instruction, require that the old compare can // be removed. if (!Cmp1->hasOneUse()) return nullptr; SubstituteCmp = Builder.CreateICmp(Pred1, Y, C); } return Builder.CreateBinOp(Logic.getOpcode(), Cmp0, SubstituteCmp); } /// Fold (icmp Pred1 V1, C1) & (icmp Pred2 V2, C2) /// or (icmp Pred1 V1, C1) | (icmp Pred2 V2, C2) /// into a single comparison using range-based reasoning. static Value *foldAndOrOfICmpsUsingRanges( ICmpInst::Predicate Pred1, Value *V1, const APInt &C1, ICmpInst::Predicate Pred2, Value *V2, const APInt &C2, IRBuilderBase &Builder, bool IsAnd) { // Look through add of a constant offset on V1, V2, or both operands. This // allows us to interpret the V + C' < C'' range idiom into a proper range. const APInt *Offset1 = nullptr, *Offset2 = nullptr; if (V1 != V2) { Value *X; if (match(V1, m_Add(m_Value(X), m_APInt(Offset1)))) V1 = X; if (match(V2, m_Add(m_Value(X), m_APInt(Offset2)))) V2 = X; } if (V1 != V2) return nullptr; ConstantRange CR1 = ConstantRange::makeExactICmpRegion(Pred1, C1); if (Offset1) CR1 = CR1.subtract(*Offset1); ConstantRange CR2 = ConstantRange::makeExactICmpRegion(Pred2, C2); if (Offset2) CR2 = CR2.subtract(*Offset2); Optional CR = IsAnd ? CR1.exactIntersectWith(CR2) : CR1.exactUnionWith(CR2); if (!CR) return nullptr; CmpInst::Predicate NewPred; APInt NewC, Offset; CR->getEquivalentICmp(NewPred, NewC, Offset); Type *Ty = V1->getType(); Value *NewV = V1; if (Offset != 0) NewV = Builder.CreateAdd(NewV, ConstantInt::get(Ty, Offset)); return Builder.CreateICmp(NewPred, NewV, ConstantInt::get(Ty, NewC)); } /// Fold (icmp)&(icmp) if possible. Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS, BinaryOperator &And) { const SimplifyQuery Q = SQ.getWithInstruction(&And); // 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, &And, /* IsAnd */ true)) 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; if (Value *V = foldAndOrOfICmpsWithConstEq(LHS, RHS, And, Builder, Q)) return V; if (Value *V = foldAndOrOfICmpsWithConstEq(RHS, LHS, And, Builder, Q)) 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, And, 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; if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/true)) return X; // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2). Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0); // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0) // TODO: Remove this when foldLogOpOfMaskedICmps can handle undefs. if (PredL == ICmpInst::ICMP_EQ && match(LHS->getOperand(1), m_ZeroInt()) && PredR == ICmpInst::ICMP_EQ && match(RHS->getOperand(1), m_ZeroInt()) && LHS0->getType() == RHS0->getType()) { Value *NewOr = Builder.CreateOr(LHS0, RHS0); return Builder.CreateICmp(PredL, NewOr, Constant::getNullValue(NewOr->getType())); } const APInt *LHSC, *RHSC; if (!match(LHS->getOperand(1), m_APInt(LHSC)) || !match(RHS->getOperand(1), m_APInt(RHSC))) return nullptr; // (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; const APInt *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_APInt(AndC)))) { SmallC = RHSC; BigC = LHSC; } else if (match(LHS0, m_Trunc(m_Value(V))) && match(RHS0, m_And(m_Specific(V), m_APInt(AndC)))) { SmallC = LHSC; BigC = RHSC; } if (SmallC && BigC) { unsigned BigBitSize = BigC->getBitWidth(); unsigned SmallBitSize = SmallC->getBitWidth(); // Check that the low bits are zero. APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize); if ((Low & *AndC).isZero() && (Low & *BigC).isZero()) { Value *NewAnd = Builder.CreateAnd(V, Low | *AndC); APInt N = SmallC->zext(BigBitSize) | *BigC; Value *NewVal = ConstantInt::get(NewAnd->getType(), N); return Builder.CreateICmp(PredL, NewAnd, NewVal); } } } return foldAndOrOfICmpsUsingRanges(PredL, LHS0, *LHSC, PredR, RHS0, *RHSC, Builder, /* IsAnd */ true); } Value *InstCombinerImpl::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. Value *BO10, *BO11; 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(Opcode, m_Value(BO10), m_Value(BO11)))) return nullptr; // The inner logic op must have a matching fcmp operand. Value *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(NewFCmp)) { // Intersect FMF from the 2 source fcmps. NewFCmpInst->copyIRFlags(Op0); NewFCmpInst->andIRFlags(BO10); } return BinaryOperator::Create(Opcode, NewFCmp, BO11); } /// Match variations of De Morgan's Laws: /// (~A & ~B) == (~(A | B)) /// (~A | ~B) == (~(A & B)) static Instruction *matchDeMorgansLaws(BinaryOperator &I, InstCombiner::BuilderTy &Builder) { const Instruction::BinaryOps 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. const Instruction::BinaryOps FlippedOpcode = (Opcode == Instruction::And) ? Instruction::Or : Instruction::And; Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *A, *B; if (match(Op0, m_OneUse(m_Not(m_Value(A)))) && match(Op1, m_OneUse(m_Not(m_Value(B)))) && !InstCombiner::isFreeToInvert(A, A->hasOneUse()) && !InstCombiner::isFreeToInvert(B, B->hasOneUse())) { Value *AndOr = Builder.CreateBinOp(FlippedOpcode, A, B, I.getName() + ".demorgan"); return BinaryOperator::CreateNot(AndOr); } // The 'not' ops may require reassociation. // (A & ~B) & ~C --> A & ~(B | C) // (~B & A) & ~C --> A & ~(B | C) // (A | ~B) | ~C --> A | ~(B & C) // (~B | A) | ~C --> A | ~(B & C) Value *C; if (match(Op0, m_OneUse(m_c_BinOp(Opcode, m_Value(A), m_Not(m_Value(B))))) && match(Op1, m_Not(m_Value(C)))) { Value *FlippedBO = Builder.CreateBinOp(FlippedOpcode, B, C); return BinaryOperator::Create(Opcode, A, Builder.CreateNot(FlippedBO)); } return nullptr; } bool InstCombinerImpl::shouldOptimizeCast(CastInst *CI) { Value *CastSrc = CI->getOperand(0); // Noop casts and casts of constants should be eliminated trivially. if (CI->getSrcTy() == CI->getDestTy() || isa(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(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(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 *InstCombinerImpl::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(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(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(Cast0Src); ICmpInst *ICmp1 = dyn_cast(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(Cast0Src); FCmpInst *FCmp1 = dyn_cast(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)); // Operand complexity canonicalization guarantees that the 'xor' is Op0. // (A ^ B) | ~(A | B) --> ~(A & B) // (A ^ B) | ~(B | A) --> ~(A & B) if (Op0->hasOneUse() || Op1->hasOneUse()) if (match(Op0, m_Xor(m_Value(A), m_Value(B))) && match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) return BinaryOperator::CreateNot(Builder.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_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) { APInt Threshold(C->getType()->getScalarSizeInBits(), BitWidth); return match(C, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, Threshold)); } /// 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 *InstCombinerImpl::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(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(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); } /// Try folding relatively complex patterns for both And and Or operations /// with all And and Or swapped. static Instruction *foldComplexAndOrPatterns(BinaryOperator &I, InstCombiner::BuilderTy &Builder) { const Instruction::BinaryOps Opcode = I.getOpcode(); assert(Opcode == Instruction::And || Opcode == Instruction::Or); // Flip the logic operation. const Instruction::BinaryOps FlippedOpcode = (Opcode == Instruction::And) ? Instruction::Or : Instruction::And; Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *A, *B, *C, *X, *Y, *Dummy; // Match following expressions: // (~(A | B) & C) // (~(A & B) | C) // Captures X = ~(A | B) or ~(A & B) const auto matchNotOrAnd = [Opcode, FlippedOpcode](Value *Op, auto m_A, auto m_B, auto m_C, Value *&X, bool CountUses = false) -> bool { if (CountUses && !Op->hasOneUse()) return false; if (match(Op, m_c_BinOp(FlippedOpcode, m_CombineAnd(m_Value(X), m_Not(m_c_BinOp(Opcode, m_A, m_B))), m_C))) return !CountUses || X->hasOneUse(); return false; }; // (~(A | B) & C) | ... --> ... // (~(A & B) | C) & ... --> ... // TODO: One use checks are conservative. We just need to check that a total // number of multiple used values does not exceed reduction // in operations. if (matchNotOrAnd(Op0, m_Value(A), m_Value(B), m_Value(C), X)) { // (~(A | B) & C) | (~(A | C) & B) --> (B ^ C) & ~A // (~(A & B) | C) & (~(A & C) | B) --> ~((B ^ C) & A) if (matchNotOrAnd(Op1, m_Specific(A), m_Specific(C), m_Specific(B), Dummy, true)) { Value *Xor = Builder.CreateXor(B, C); return (Opcode == Instruction::Or) ? BinaryOperator::CreateAnd(Xor, Builder.CreateNot(A)) : BinaryOperator::CreateNot(Builder.CreateAnd(Xor, A)); } // (~(A | B) & C) | (~(B | C) & A) --> (A ^ C) & ~B // (~(A & B) | C) & (~(B & C) | A) --> ~((A ^ C) & B) if (matchNotOrAnd(Op1, m_Specific(B), m_Specific(C), m_Specific(A), Dummy, true)) { Value *Xor = Builder.CreateXor(A, C); return (Opcode == Instruction::Or) ? BinaryOperator::CreateAnd(Xor, Builder.CreateNot(B)) : BinaryOperator::CreateNot(Builder.CreateAnd(Xor, B)); } // (~(A | B) & C) | ~(A | C) --> ~((B & C) | A) // (~(A & B) | C) & ~(A & C) --> ~((B | C) & A) if (match(Op1, m_OneUse(m_Not(m_OneUse( m_c_BinOp(Opcode, m_Specific(A), m_Specific(C))))))) return BinaryOperator::CreateNot(Builder.CreateBinOp( Opcode, Builder.CreateBinOp(FlippedOpcode, B, C), A)); // (~(A | B) & C) | ~(B | C) --> ~((A & C) | B) // (~(A & B) | C) & ~(B & C) --> ~((A | C) & B) if (match(Op1, m_OneUse(m_Not(m_OneUse( m_c_BinOp(Opcode, m_Specific(B), m_Specific(C))))))) return BinaryOperator::CreateNot(Builder.CreateBinOp( Opcode, Builder.CreateBinOp(FlippedOpcode, A, C), B)); // (~(A | B) & C) | ~(C | (A ^ B)) --> ~((A | B) & (C | (A ^ B))) // Note, the pattern with swapped and/or is not handled because the // result is more undefined than a source: // (~(A & B) | C) & ~(C & (A ^ B)) --> (A ^ B ^ C) | ~(A | C) is invalid. if (Opcode == Instruction::Or && Op0->hasOneUse() && match(Op1, m_OneUse(m_Not(m_CombineAnd( m_Value(Y), m_c_BinOp(Opcode, m_Specific(C), m_c_Xor(m_Specific(A), m_Specific(B)))))))) { // X = ~(A | B) // Y = (C | (A ^ B) Value *Or = cast(X)->getOperand(0); return BinaryOperator::CreateNot(Builder.CreateAnd(Or, Y)); } } // (~A & B & C) | ... --> ... // (~A | B | C) | ... --> ... // TODO: One use checks are conservative. We just need to check that a total // number of multiple used values does not exceed reduction // in operations. if (match(Op0, m_OneUse(m_c_BinOp(FlippedOpcode, m_BinOp(FlippedOpcode, m_Value(B), m_Value(C)), m_CombineAnd(m_Value(X), m_Not(m_Value(A)))))) || match(Op0, m_OneUse(m_c_BinOp( FlippedOpcode, m_c_BinOp(FlippedOpcode, m_Value(C), m_CombineAnd(m_Value(X), m_Not(m_Value(A)))), m_Value(B))))) { // X = ~A // (~A & B & C) | ~(A | B | C) --> ~(A | (B ^ C)) // (~A | B | C) & ~(A & B & C) --> (~A | (B ^ C)) if (match(Op1, m_OneUse(m_Not(m_c_BinOp( Opcode, m_c_BinOp(Opcode, m_Specific(A), m_Specific(B)), m_Specific(C))))) || match(Op1, m_OneUse(m_Not(m_c_BinOp( Opcode, m_c_BinOp(Opcode, m_Specific(B), m_Specific(C)), m_Specific(A))))) || match(Op1, m_OneUse(m_Not(m_c_BinOp( Opcode, m_c_BinOp(Opcode, m_Specific(A), m_Specific(C)), m_Specific(B)))))) { Value *Xor = Builder.CreateXor(B, C); return (Opcode == Instruction::Or) ? BinaryOperator::CreateNot(Builder.CreateOr(Xor, A)) : BinaryOperator::CreateOr(Xor, X); } // (~A & B & C) | ~(A | B) --> (C | ~B) & ~A // (~A | B | C) & ~(A & B) --> (C & ~B) | ~A if (match(Op1, m_OneUse(m_Not(m_OneUse( m_c_BinOp(Opcode, m_Specific(A), m_Specific(B))))))) return BinaryOperator::Create( FlippedOpcode, Builder.CreateBinOp(Opcode, C, Builder.CreateNot(B)), X); // (~A & B & C) | ~(A | C) --> (B | ~C) & ~A // (~A | B | C) & ~(A & C) --> (B & ~C) | ~A if (match(Op1, m_OneUse(m_Not(m_OneUse( m_c_BinOp(Opcode, m_Specific(A), m_Specific(C))))))) return BinaryOperator::Create( FlippedOpcode, Builder.CreateBinOp(Opcode, B, Builder.CreateNot(C)), X); } 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 *InstCombinerImpl::visitAnd(BinaryOperator &I) { Type *Ty = I.getType(); 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; if (Instruction *Phi = foldBinopWithPhiOperands(I)) return Phi; // 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; if (Instruction *X = foldComplexAndOrPatterns(I, Builder)) return X; // (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); Value *X, *Y; if (match(Op0, m_OneUse(m_LogicalShift(m_One(), m_Value(X)))) && match(Op1, m_One())) { // (1 << X) & 1 --> zext(X == 0) // (1 >> X) & 1 --> zext(X == 0) Value *IsZero = Builder.CreateICmpEQ(X, ConstantInt::get(Ty, 0)); return new ZExtInst(IsZero, Ty); } const APInt *C; if (match(Op1, m_APInt(C))) { 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(Ty, *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(Ty, Together ^ *C)); And->takeName(Op0); return BinaryOperator::CreateOr(And, ConstantInt::get(Ty, 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(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(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); } } unsigned Width = Ty->getScalarSizeInBits(); const APInt *ShiftC; if (match(Op0, m_OneUse(m_SExt(m_AShr(m_Value(X), m_APInt(ShiftC)))))) { if (*C == APInt::getLowBitsSet(Width, Width - ShiftC->getZExtValue())) { // We are clearing high bits that were potentially set by sext+ashr: // and (sext (ashr X, ShiftC)), C --> lshr (sext X), ShiftC Value *Sext = Builder.CreateSExt(X, Ty); Constant *ShAmtC = ConstantInt::get(Ty, ShiftC->zext(Width)); return BinaryOperator::CreateLShr(Sext, ShAmtC); } } // If this 'and' clears the sign-bits added by ashr, replace with lshr: // and (ashr X, ShiftC), C --> lshr X, ShiftC if (match(Op0, m_AShr(m_Value(X), m_APInt(ShiftC))) && ShiftC->ult(Width) && C->isMask(Width - ShiftC->getZExtValue())) return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, *ShiftC)); const APInt *AddC; if (match(Op0, m_Add(m_Value(X), m_APInt(AddC)))) { // If we add zeros to every bit below a mask, the add has no effect: // (X + AddC) & LowMaskC --> X & LowMaskC unsigned Ctlz = C->countLeadingZeros(); APInt LowMask(APInt::getLowBitsSet(Width, Width - Ctlz)); if ((*AddC & LowMask).isZero()) return BinaryOperator::CreateAnd(X, Op1); // If we are masking the result of the add down to exactly one bit and // the constant we are adding has no bits set below that bit, then the // add is flipping a single bit. Example: // (X + 4) & 4 --> (X & 4) ^ 4 if (Op0->hasOneUse() && C->isPowerOf2() && (*AddC & (*C - 1)) == 0) { assert((*C & *AddC) != 0 && "Expected common bit"); Value *NewAnd = Builder.CreateAnd(X, Op1); return BinaryOperator::CreateXor(NewAnd, Op1); } } // ((C1 OP zext(X)) & C2) -> zext((C1 OP X) & C2) if C2 fits in the // bitwidth of X and OP behaves well when given trunc(C1) and X. auto isSuitableBinOpcode = [](BinaryOperator *B) { switch (B->getOpcode()) { case Instruction::Xor: case Instruction::Or: case Instruction::Mul: case Instruction::Add: case Instruction::Sub: return true; default: return false; } }; BinaryOperator *BO; if (match(Op0, m_OneUse(m_BinOp(BO))) && isSuitableBinOpcode(BO)) { Value *X; const APInt *C1; // TODO: The one-use restrictions could be relaxed a little if the AND // is going to be removed. if (match(BO, m_c_BinOp(m_OneUse(m_ZExt(m_Value(X))), m_APInt(C1))) && C->isIntN(X->getType()->getScalarSizeInBits())) { unsigned XWidth = X->getType()->getScalarSizeInBits(); Constant *TruncC1 = ConstantInt::get(X->getType(), C1->trunc(XWidth)); Value *BinOp = isa(BO->getOperand(0)) ? Builder.CreateBinOp(BO->getOpcode(), X, TruncC1) : Builder.CreateBinOp(BO->getOpcode(), TruncC1, X); Constant *TruncC = ConstantInt::get(X->getType(), C->trunc(XWidth)); Value *And = Builder.CreateAnd(BinOp, TruncC); return new ZExtInst(And, Ty); } } } if (match(&I, m_And(m_OneUse(m_Shl(m_ZExt(m_Value(X)), m_Value(Y))), m_SignMask())) && match(Y, m_SpecificInt_ICMP( ICmpInst::Predicate::ICMP_EQ, APInt(Ty->getScalarSizeInBits(), Ty->getScalarSizeInBits() - X->getType()->getScalarSizeInBits())))) { auto *SExt = Builder.CreateSExt(X, Ty, X->getName() + ".signext"); auto *SanitizedSignMask = cast(Op1); // We must be careful with the undef elements of the sign bit mask, however: // the mask elt can be undef iff the shift amount for that lane was undef, // otherwise we need to sanitize undef masks to zero. SanitizedSignMask = Constant::replaceUndefsWith( SanitizedSignMask, ConstantInt::getNullValue(Ty->getScalarType())); SanitizedSignMask = Constant::mergeUndefsWith(SanitizedSignMask, cast(Y)); return BinaryOperator::CreateAnd(SExt, SanitizedSignMask); } if (Instruction *Z = narrowMaskedBinOp(I)) return Z; if (I.getType()->isIntOrIntVectorTy(1)) { if (auto *SI0 = dyn_cast(Op0)) { if (auto *I = foldAndOrOfSelectUsingImpliedCond(Op1, *SI0, /* IsAnd */ true)) return I; } if (auto *SI1 = dyn_cast(Op1)) { if (auto *I = foldAndOrOfSelectUsingImpliedCond(Op0, *SI1, /* IsAnd */ true)) return I; } } 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 & ~(A ^ B) --> A & B if (match(Op1, m_Not(m_c_Xor(m_Specific(Op0), m_Value(B))))) return BinaryOperator::CreateAnd(Op0, B); // ~(A ^ B) & A --> A & B if (match(Op0, m_Not(m_c_Xor(m_Specific(Op1), m_Value(B))))) return BinaryOperator::CreateAnd(Op1, 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); // (~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_Or(m_Not(m_Value(A)), m_Value(B))) && match(Op1, m_c_Xor(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateAnd(Builder.CreateNot(A), B); // (A ^ B) & (~A | B) -> ~A & B // (B ^ A) & (~A | B) -> ~A & B // (A ^ B) & (B | ~A) -> ~A & B // (B ^ A) & (B | ~A) -> ~A & B if (match(Op1, m_c_Or(m_Not(m_Value(A)), m_Value(B))) && match(Op0, m_c_Xor(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateAnd(Builder.CreateNot(A), B); } { ICmpInst *LHS = dyn_cast(Op0); ICmpInst *RHS = dyn_cast(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. if (LHS && match(Op1, m_OneUse(m_And(m_Value(X), m_Value(Y))))) { if (auto *Cmp = dyn_cast(X)) if (Value *Res = foldAndOfICmps(LHS, Cmp, I)) return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y)); if (auto *Cmp = dyn_cast(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(X)) if (Value *Res = foldAndOfICmps(Cmp, RHS, I)) return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y)); if (auto *Cmp = dyn_cast(Y)) if (Value *Res = foldAndOfICmps(Cmp, RHS, I)) return replaceInstUsesWith(I, Builder.CreateAnd(Res, X)); } } if (FCmpInst *LHS = dyn_cast(I.getOperand(0))) if (FCmpInst *RHS = dyn_cast(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; if (Instruction *Sel = foldBinopOfSextBoolToSelect(I)) return Sel; // and(sext(A), B) / and(B, sext(A)) --> A ? B : 0, where A is i1 or . // TODO: Move this into foldBinopOfSextBoolToSelect as a more generalized fold // with binop identity constant. But creating a select with non-constant // arm may not be reversible due to poison semantics. Is that a good // canonicalization? Value *A; if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) && A->getType()->isIntOrIntVectorTy(1)) return SelectInst::Create(A, Op1, Constant::getNullValue(Ty)); if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) && A->getType()->isIntOrIntVectorTy(1)) return SelectInst::Create(A, Op0, Constant::getNullValue(Ty)); // (iN X s>> (N-1)) & Y --> (X s< 0) ? Y : 0 unsigned FullShift = Ty->getScalarSizeInBits() - 1; if (match(&I, m_c_And(m_OneUse(m_AShr(m_Value(X), m_SpecificInt(FullShift))), m_Value(Y)))) { Constant *Zero = ConstantInt::getNullValue(Ty); Value *Cmp = Builder.CreateICmpSLT(X, Zero, "isneg"); return SelectInst::Create(Cmp, Y, Zero); } // If there's a 'not' of the shifted value, swap the select operands: // ~(iN X s>> (N-1)) & Y --> (X s< 0) ? 0 : Y if (match(&I, m_c_And(m_OneUse(m_Not( m_AShr(m_Value(X), m_SpecificInt(FullShift)))), m_Value(Y)))) { Constant *Zero = ConstantInt::getNullValue(Ty); Value *Cmp = Builder.CreateICmpSLT(X, Zero, "isneg"); return SelectInst::Create(Cmp, Zero, Y); } // (~x) & y --> ~(x | (~y)) iff that gets rid of inversions if (sinkNotIntoOtherHandOfAndOrOr(I)) return &I; // An and recurrence w/loop invariant step is equivelent to (and start, step) PHINode *PN = nullptr; Value *Start = nullptr, *Step = nullptr; if (matchSimpleRecurrence(&I, PN, Start, Step) && DT.dominates(Step, PN)) return replaceInstUsesWith(I, Builder.CreateAnd(Start, Step)); return nullptr; } Instruction *InstCombinerImpl::matchBSwapOrBitReverse(Instruction &I, bool MatchBSwaps, bool MatchBitReversals) { SmallVector Insts; if (!recognizeBSwapOrBitReverseIdiom(&I, MatchBSwaps, MatchBitReversals, Insts)) return nullptr; Instruction *LastInst = Insts.pop_back_val(); LastInst->removeFromParent(); for (auto *Inst : Insts) Worklist.push(Inst); return LastInst; } /// Match UB-safe variants of the funnel shift intrinsic. static Instruction *matchFunnelShift(Instruction &Or, InstCombinerImpl &IC) { // TODO: Can we reduce the code duplication between this and the related // rotate matching code under visitSelect and visitTrunc? unsigned Width = Or.getType()->getScalarSizeInBits(); // First, find an or'd pair of opposite shifts: // or (lshr ShVal0, ShAmt0), (shl ShVal1, ShAmt1) BinaryOperator *Or0, *Or1; if (!match(Or.getOperand(0), m_BinOp(Or0)) || !match(Or.getOperand(1), m_BinOp(Or1))) return nullptr; Value *ShVal0, *ShVal1, *ShAmt0, *ShAmt1; if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal0), m_Value(ShAmt0)))) || !match(Or1, m_OneUse(m_LogicalShift(m_Value(ShVal1), m_Value(ShAmt1)))) || Or0->getOpcode() == Or1->getOpcode()) return nullptr; // Canonicalize to or(shl(ShVal0, ShAmt0), lshr(ShVal1, ShAmt1)). if (Or0->getOpcode() == BinaryOperator::LShr) { std::swap(Or0, Or1); std::swap(ShVal0, ShVal1); std::swap(ShAmt0, ShAmt1); } assert(Or0->getOpcode() == BinaryOperator::Shl && Or1->getOpcode() == BinaryOperator::LShr && "Illegal or(shift,shift) pair"); // Match the shift amount operands for a funnel shift pattern. This always // matches a subtraction on the R operand. auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * { // Check for constant shift amounts that sum to the bitwidth. const APInt *LI, *RI; if (match(L, m_APIntAllowUndef(LI)) && match(R, m_APIntAllowUndef(RI))) if (LI->ult(Width) && RI->ult(Width) && (*LI + *RI) == Width) return ConstantInt::get(L->getType(), *LI); Constant *LC, *RC; if (match(L, m_Constant(LC)) && match(R, m_Constant(RC)) && match(L, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) && match(R, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) && match(ConstantExpr::getAdd(LC, RC), m_SpecificIntAllowUndef(Width))) return ConstantExpr::mergeUndefsWith(LC, RC); // (shl ShVal, X) | (lshr ShVal, (Width - x)) iff X < Width. // We limit this to X < Width in case the backend re-expands the intrinsic, // and has to reintroduce a shift modulo operation (InstCombine might remove // it after this fold). This still doesn't guarantee that the final codegen // will match this original pattern. if (match(R, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(L))))) { KnownBits KnownL = IC.computeKnownBits(L, /*Depth*/ 0, &Or); return KnownL.getMaxValue().ult(Width) ? L : nullptr; } // For non-constant cases, the following patterns currently only work for // rotation patterns. // TODO: Add general funnel-shift compatible patterns. if (ShVal0 != ShVal1) return nullptr; // For non-constant cases we don't support non-pow2 shift masks. // TODO: Is it worth matching urem as well? if (!isPowerOf2_32(Width)) return nullptr; // 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; if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) && match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))) return L; return nullptr; }; Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, Width); bool IsFshl = true; // Sub on LSHR. if (!ShAmt) { ShAmt = matchShiftAmount(ShAmt1, ShAmt0, Width); IsFshl = false; // Sub on SHL. } if (!ShAmt) return nullptr; Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr; Function *F = Intrinsic::getDeclaration(Or.getModule(), IID, Or.getType()); return CallInst::Create(F, {ShVal0, ShVal1, ShAmt}); } /// Attempt to combine or(zext(x),shl(zext(y),bw/2) concat packing patterns. static Instruction *matchOrConcat(Instruction &Or, InstCombiner::BuilderTy &Builder) { assert(Or.getOpcode() == Instruction::Or && "bswap requires an 'or'"); Value *Op0 = Or.getOperand(0), *Op1 = Or.getOperand(1); Type *Ty = Or.getType(); unsigned Width = Ty->getScalarSizeInBits(); if ((Width & 1) != 0) return nullptr; unsigned HalfWidth = Width / 2; // Canonicalize zext (lower half) to LHS. if (!isa(Op0)) std::swap(Op0, Op1); // Find lower/upper half. Value *LowerSrc, *ShlVal, *UpperSrc; const APInt *C; if (!match(Op0, m_OneUse(m_ZExt(m_Value(LowerSrc)))) || !match(Op1, m_OneUse(m_Shl(m_Value(ShlVal), m_APInt(C)))) || !match(ShlVal, m_OneUse(m_ZExt(m_Value(UpperSrc))))) return nullptr; if (*C != HalfWidth || LowerSrc->getType() != UpperSrc->getType() || LowerSrc->getType()->getScalarSizeInBits() != HalfWidth) return nullptr; auto ConcatIntrinsicCalls = [&](Intrinsic::ID id, Value *Lo, Value *Hi) { Value *NewLower = Builder.CreateZExt(Lo, Ty); Value *NewUpper = Builder.CreateZExt(Hi, Ty); NewUpper = Builder.CreateShl(NewUpper, HalfWidth); Value *BinOp = Builder.CreateOr(NewLower, NewUpper); Function *F = Intrinsic::getDeclaration(Or.getModule(), id, Ty); return Builder.CreateCall(F, BinOp); }; // BSWAP: Push the concat down, swapping the lower/upper sources. // concat(bswap(x),bswap(y)) -> bswap(concat(x,y)) Value *LowerBSwap, *UpperBSwap; if (match(LowerSrc, m_BSwap(m_Value(LowerBSwap))) && match(UpperSrc, m_BSwap(m_Value(UpperBSwap)))) return ConcatIntrinsicCalls(Intrinsic::bswap, UpperBSwap, LowerBSwap); // BITREVERSE: Push the concat down, swapping the lower/upper sources. // concat(bitreverse(x),bitreverse(y)) -> bitreverse(concat(x,y)) Value *LowerBRev, *UpperBRev; if (match(LowerSrc, m_BitReverse(m_Value(LowerBRev))) && match(UpperSrc, m_BitReverse(m_Value(UpperBRev)))) return ConcatIntrinsicCalls(Intrinsic::bitreverse, UpperBRev, LowerBRev); return nullptr; } /// If all elements of two constant vectors are 0/-1 and inverses, return true. static bool areInverseVectorBitmasks(Constant *C1, Constant *C2) { unsigned NumElts = cast(C1->getType())->getNumElements(); 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 *InstCombinerImpl::getSelectCondition(Value *A, Value *B) { // 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; // If A is the 'not' operand of B and has enough signbits, we have our answer. if (match(B, m_Not(m_Specific(A)))) { // If these are scalars or vectors of i1, A can be used directly. if (Ty->isIntOrIntVectorTy(1)) return A; // If we look through a vector bitcast, the caller will bitcast the operands // to match the condition's number of bits (N x i1). // To make this poison-safe, disallow bitcast from wide element to narrow // element. That could allow poison in lanes where it was not present in the // original code. A = peekThroughBitcast(A); if (A->getType()->isIntOrIntVectorTy()) { unsigned NumSignBits = ComputeNumSignBits(A); if (NumSignBits == A->getType()->getScalarSizeInBits() && NumSignBits <= Ty->getScalarSizeInBits()) return Builder.CreateTrunc(A, CmpInst::makeCmpResultType(A->getType())); } return nullptr; } // 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) && ComputeNumSignBits(A) == Ty->getScalarSizeInBits()) 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)) { // A = sext i1 Cond; B = sext (not (i1 Cond)) if (match(B, m_SExt(m_Not(m_Specific(Cond))))) return Cond; // A = sext i1 Cond; B = not ({bitcast} (sext (i1 Cond))) // TODO: The one-use checks are unnecessary or misplaced. If the caller // checked for uses on logic ops/casts, that should be enough to // make this transform worthwhile. if (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 *InstCombinerImpl::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)) // If this is a vector, we may need to cast to match the condition's length. // The bitcasts will either all exist or all not exist. The builder will // not create unnecessary casts if the types already match. Type *SelTy = A->getType(); if (auto *VecTy = dyn_cast(Cond->getType())) { // For a fixed or scalable vector get N from <{vscale x} N x iM> unsigned Elts = VecTy->getElementCount().getKnownMinValue(); // For a fixed or scalable vector, get the size in bits of N x iM; for a // scalar this is just M. unsigned SelEltSize = SelTy->getPrimitiveSizeInBits().getKnownMinSize(); Type *EltTy = Builder.getIntNTy(SelEltSize / Elts); SelTy = VectorType::get(EltTy, VecTy->getElementCount()); } Value *BitcastC = Builder.CreateBitCast(C, SelTy); Value *BitcastD = Builder.CreateBitCast(D, SelTy); Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastD); return Builder.CreateBitCast(Select, OrigType); } return nullptr; } /// Fold (icmp)|(icmp) if possible. Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, BinaryOperator &Or) { const SimplifyQuery Q = SQ.getWithInstruction(&Or); // 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, &Or, /* IsAnd */ false)) return V; ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0); Value *LHS1 = LHS->getOperand(1), *RHS1 = RHS->getOperand(1); const APInt *LHSC = nullptr, *RHSC = nullptr; match(LHS1, m_APInt(LHSC)); match(RHS1, m_APInt(RHSC)); // 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->getBitWidth() == RHSC->getBitWidth() && *LHSC == *RHSC) { Value *AddOpnd; const APInt *LAddC, *RAddC; if (match(LHS0, m_Add(m_Value(AddOpnd), m_APInt(LAddC))) && match(RHS0, m_Add(m_Specific(AddOpnd), m_APInt(RAddC))) && LAddC->ugt(*LHSC) && RAddC->ugt(*LHSC)) { APInt DiffC = *LAddC ^ *RAddC; if (DiffC.isPowerOf2()) { const APInt *MaxAddC = nullptr; if (LAddC->ult(*RAddC)) MaxAddC = RAddC; else MaxAddC = LAddC; APInt RRangeLow = -*RAddC; APInt RRangeHigh = RRangeLow + *LHSC; APInt LRangeLow = -*LAddC; APInt LRangeHigh = LRangeLow + *LHSC; 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)) { Type *Ty = AddOpnd->getType(); Value *MaskC = ConstantInt::get(Ty, ~DiffC); Value *NewAnd = Builder.CreateAnd(AddOpnd, MaskC); Value *NewAdd = Builder.CreateAdd(NewAnd, ConstantInt::get(Ty, *MaxAddC)); return Builder.CreateICmp(LHS->getPredicate(), NewAdd, ConstantInt::get(Ty, *LHSC)); } } } } // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B) if (predicatesFoldable(PredL, PredR)) { if (LHS0 == RHS1 && LHS1 == RHS0) LHS->swapOperands(); if (LHS0 == RHS0 && LHS1 == RHS1) { unsigned Code = getICmpCode(LHS) | getICmpCode(RHS); bool IsSigned = LHS->isSigned() || RHS->isSigned(); return getNewICmpValue(Code, IsSigned, LHS0, LHS1, Builder); } } // handle (roughly): // (icmp ne (A & B), C) | (icmp ne (A & D), E) if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder)) return V; 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 && match(LHS1, m_Zero())) { B = LHS0; if (PredR == ICmpInst::ICMP_ULT && LHS0 == RHS1) A = RHS0; else if (PredR == ICmpInst::ICMP_UGT && LHS0 == RHS0) A = RHS1; } // (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 && match(RHS1, m_Zero())) { B = RHS0; if (PredL == ICmpInst::ICMP_ULT && RHS0 == LHS1) A = LHS0; else if (PredL == ICmpInst::ICMP_UGT && RHS0 == LHS0) A = LHS1; } if (A && B && B->getType()->isIntOrIntVectorTy()) return Builder.CreateICmp( ICmpInst::ICMP_UGE, Builder.CreateAdd(B, Constant::getAllOnesValue(B->getType())), A); } if (Value *V = foldAndOrOfICmpsWithConstEq(LHS, RHS, Or, Builder, Q)) return V; if (Value *V = foldAndOrOfICmpsWithConstEq(RHS, LHS, Or, Builder, Q)) return V; // 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; if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/false)) return X; // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0) // TODO: Remove this when foldLogOpOfMaskedICmps can handle undefs. if (PredL == ICmpInst::ICMP_NE && match(LHS1, m_ZeroInt()) && PredR == ICmpInst::ICMP_NE && match(RHS1, m_ZeroInt()) && LHS0->getType() == RHS0->getType()) { Value *NewOr = Builder.CreateOr(LHS0, RHS0); return Builder.CreateICmp(PredL, NewOr, Constant::getNullValue(NewOr->getType())); } // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2). if (!LHSC || !RHSC) return nullptr; return foldAndOrOfICmpsUsingRanges(PredL, LHS0, *LHSC, PredR, RHS0, *RHSC, Builder, /* IsAnd */ false); } // 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 *InstCombinerImpl::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; if (Instruction *Phi = foldBinopWithPhiOperands(I)) return Phi; // 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; if (Instruction *X = foldComplexAndOrPatterns(I, Builder)) return X; // (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); Type *Ty = I.getType(); if (Ty->isIntOrIntVectorTy(1)) { if (auto *SI0 = dyn_cast(Op0)) { if (auto *I = foldAndOrOfSelectUsingImpliedCond(Op1, *SI0, /* IsAnd */ false)) return I; } if (auto *SI1 = dyn_cast(Op1)) { if (auto *I = foldAndOrOfSelectUsingImpliedCond(Op0, *SI1, /* IsAnd */ false)) return I; } } if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I)) return FoldedLogic; if (Instruction *BitOp = matchBSwapOrBitReverse(I, /*MatchBSwaps*/ true, /*MatchBitReversals*/ true)) return BitOp; if (Instruction *Funnel = matchFunnelShift(I, *this)) return Funnel; if (Instruction *Concat = matchOrConcat(I, Builder)) return replaceInstUsesWith(I, Concat); 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->isAllOnes() && 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(Ty, *CV)); } // If the operands have no common bits set: // or (mul X, Y), X --> add (mul X, Y), X --> mul X, (Y + 1) if (match(&I, m_c_Or(m_OneUse(m_Mul(m_Value(X), m_Value(Y))), m_Deferred(X))) && haveNoCommonBitsSet(Op0, Op1, DL)) { Value *IncrementY = Builder.CreateAdd(Y, ConstantInt::get(Ty, 1)); return BinaryOperator::CreateMul(X, IncrementY); } // (A & C) | (B & D) 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)))) { // (A & C0) | (B & C1) const APInt *C0, *C1; if (match(C, m_APInt(C0)) && match(D, m_APInt(C1))) { Value *X; if (*C0 == ~*C1) { // ((X | B) & MaskC) | (B & ~MaskC) -> (X & MaskC) | B if (match(A, m_c_Or(m_Value(X), m_Specific(B)))) return BinaryOperator::CreateOr(Builder.CreateAnd(X, *C0), B); // (A & MaskC) | ((X | A) & ~MaskC) -> (X & ~MaskC) | A if (match(B, m_c_Or(m_Specific(A), m_Value(X)))) return BinaryOperator::CreateOr(Builder.CreateAnd(X, *C1), A); // ((X ^ B) & MaskC) | (B & ~MaskC) -> (X & MaskC) ^ B if (match(A, m_c_Xor(m_Value(X), m_Specific(B)))) return BinaryOperator::CreateXor(Builder.CreateAnd(X, *C0), B); // (A & MaskC) | ((X ^ A) & ~MaskC) -> (X & ~MaskC) ^ A if (match(B, m_c_Xor(m_Specific(A), m_Value(X)))) return BinaryOperator::CreateXor(Builder.CreateAnd(X, *C1), A); } if ((*C0 & *C1).isZero()) { // ((X | B) & C0) | (B & C1) --> (X | B) & (C0 | C1) // iff (C0 & C1) == 0 and (X & ~C0) == 0 if (match(A, m_c_Or(m_Value(X), m_Specific(B))) && MaskedValueIsZero(X, ~*C0, 0, &I)) { Constant *C01 = ConstantInt::get(Ty, *C0 | *C1); return BinaryOperator::CreateAnd(A, C01); } // (A & C0) | ((X | A) & C1) --> (X | A) & (C0 | C1) // iff (C0 & C1) == 0 and (X & ~C1) == 0 if (match(B, m_c_Or(m_Value(X), m_Specific(A))) && MaskedValueIsZero(X, ~*C1, 0, &I)) { Constant *C01 = ConstantInt::get(Ty, *C0 | *C1); return BinaryOperator::CreateAnd(B, C01); } // ((X | C2) & C0) | ((X | C3) & C1) --> (X | C2 | C3) & (C0 | C1) // iff (C0 & C1) == 0 and (C2 & ~C0) == 0 and (C3 & ~C1) == 0. const APInt *C2, *C3; if (match(A, m_Or(m_Value(X), m_APInt(C2))) && match(B, m_Or(m_Specific(X), m_APInt(C3))) && (*C2 & ~*C0).isZero() && (*C3 & ~*C1).isZero()) { Value *Or = Builder.CreateOr(X, *C2 | *C3, "bitfield"); Constant *C01 = ConstantInt::get(Ty, *C0 | *C1); return BinaryOperator::CreateAnd(Or, C01); } } } // 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) // ~A | (A ^ B) -> ~(A & B) // The swap above should always make Op0 the 'not' for the last case. 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 ((Op0->hasOneUse() || Op1->hasOneUse()) && (match(Op0, m_Not(m_Specific(A))) || match(Op0, m_Not(m_Specific(B))))) return BinaryOperator::CreateNot(Builder.CreateAnd(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(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(Op0); ICmpInst *RHS = dyn_cast(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(X)) if (Value *Res = foldOrOfICmps(LHS, Cmp, I)) return replaceInstUsesWith(I, Builder.CreateOr(Res, Y)); if (auto *Cmp = dyn_cast(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(X)) if (Value *Res = foldOrOfICmps(Cmp, RHS, I)) return replaceInstUsesWith(I, Builder.CreateOr(Res, Y)); if (auto *Cmp = dyn_cast(Y)) if (Value *Res = foldOrOfICmps(Cmp, RHS, I)) return replaceInstUsesWith(I, Builder.CreateOr(Res, X)); } } if (FCmpInst *LHS = dyn_cast(I.getOperand(0))) if (FCmpInst *RHS = dyn_cast(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; if (Instruction *Sel = foldBinopOfSextBoolToSelect(I)) return Sel; // or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or . // TODO: Move this into foldBinopOfSextBoolToSelect as a more generalized fold // with binop identity constant. But creating a select with non-constant // arm may not be reversible due to poison semantics. Is that a good // canonicalization? if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) && A->getType()->isIntOrIntVectorTy(1)) return SelectInst::Create(A, ConstantInt::getAllOnesValue(Ty), Op1); if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) && A->getType()->isIntOrIntVectorTy(1)) return SelectInst::Create(A, ConstantInt::getAllOnesValue(Ty), 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() && !match(Op1, m_ConstantInt()) && 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; if (match(&I, m_c_Or(m_OneUse(m_AShr( m_NSWSub(m_Value(Y), m_Value(X)), m_SpecificInt(Ty->getScalarSizeInBits() - 1))), m_Deferred(X)))) { Value *NewICmpInst = Builder.CreateICmpSGT(X, Y); Value *AllOnes = ConstantInt::getAllOnesValue(Ty); return SelectInst::Create(NewICmpInst, AllOnes, X); } } if (Instruction *V = canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I)) return V; CmpInst::Predicate Pred; Value *Mul, *Ov, *MulIsNotZero, *UMulWithOv; // Check if the OR weakens the overflow condition for umul.with.overflow by // treating any non-zero result as overflow. In that case, we overflow if both // umul.with.overflow operands are != 0, as in that case the result can only // be 0, iff the multiplication overflows. if (match(&I, m_c_Or(m_CombineAnd(m_ExtractValue<1>(m_Value(UMulWithOv)), m_Value(Ov)), m_CombineAnd(m_ICmp(Pred, m_CombineAnd(m_ExtractValue<0>( m_Deferred(UMulWithOv)), m_Value(Mul)), m_ZeroInt()), m_Value(MulIsNotZero)))) && (Ov->hasOneUse() || (MulIsNotZero->hasOneUse() && Mul->hasOneUse())) && Pred == CmpInst::ICMP_NE) { Value *A, *B; if (match(UMulWithOv, m_Intrinsic( m_Value(A), m_Value(B)))) { Value *NotNullA = Builder.CreateIsNotNull(A); Value *NotNullB = Builder.CreateIsNotNull(B); return BinaryOperator::CreateAnd(NotNullA, NotNullB); } } // (~x) | y --> ~(x & (~y)) iff that gets rid of inversions if (sinkNotIntoOtherHandOfAndOrOr(I)) return &I; // Improve "get low bit mask up to and including bit X" pattern: // (1 << X) | ((1 << X) + -1) --> -1 l>> (bitwidth(x) - 1 - X) if (match(&I, m_c_Or(m_Add(m_Shl(m_One(), m_Value(X)), m_AllOnes()), m_Shl(m_One(), m_Deferred(X)))) && match(&I, m_c_Or(m_OneUse(m_Value()), m_Value()))) { Value *Sub = Builder.CreateSub( ConstantInt::get(Ty, Ty->getScalarSizeInBits() - 1), X); return BinaryOperator::CreateLShr(Constant::getAllOnesValue(Ty), Sub); } // An or recurrence w/loop invariant step is equivelent to (or start, step) PHINode *PN = nullptr; Value *Start = nullptr, *Step = nullptr; if (matchSimpleRecurrence(&I, PN, Start, Step) && DT.dominates(Step, PN)) return replaceInstUsesWith(I, Builder.CreateOr(Start, Step)); 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))))) return BinaryOperator::CreateXor(A, B); // (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))))) return BinaryOperator::CreateXor(A, B); // (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))))) return BinaryOperator::CreateXor(A, B); // 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 *InstCombinerImpl::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. Worklist.pushUsersToWorkList(*Y); 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))) { // Propagating undef is unsafe. Clamp undef elements to -1. Type *EltTy = C->getType()->getScalarType(); C = Constant::replaceUndefsWith(C, ConstantInt::getAllOnesValue(EltTy)); // 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 (InstCombiner::isFreeToInvert(X, X->hasOneUse())) { // Ok, good. } else if (InstCombiner::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"); } /// Canonicalize a shifty way to code absolute value to the more common pattern /// that uses negation and select. static Instruction *canonicalizeAbs(BinaryOperator &Xor, InstCombiner::BuilderTy &Builder) { assert(Xor.getOpcode() == Instruction::Xor && "Expected an xor instruction."); // 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). Value *Op0 = Xor.getOperand(0), *Op1 = Xor.getOperand(1); if (Op0->hasNUses(2)) std::swap(Op0, Op1); Type *Ty = Xor.getType(); Value *A; const APInt *ShAmt; 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))))) { // Op1 = ashr i32 A, 31 ; smear the sign bit // xor (add A, Op1), Op1 ; 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(Op0); Value *Neg = Builder.CreateNeg(A, "", Add->hasNoUnsignedWrap(), Add->hasNoSignedWrap()); return SelectInst::Create(Cmp, Neg, A); } return nullptr; } // Transform // z = (~x) &/| y // into: // z = ~(x |/& (~y)) // iff y is free to invert and all uses of z can be freely updated. bool InstCombinerImpl::sinkNotIntoOtherHandOfAndOrOr(BinaryOperator &I) { Instruction::BinaryOps NewOpc; switch (I.getOpcode()) { case Instruction::And: NewOpc = Instruction::Or; break; case Instruction::Or: NewOpc = Instruction::And; break; default: return false; }; Value *X, *Y; if (!match(&I, m_c_BinOp(m_Not(m_Value(X)), m_Value(Y)))) return false; // Will we be able to fold the `not` into Y eventually? if (!InstCombiner::isFreeToInvert(Y, Y->hasOneUse())) return false; // And can our users be adapted? if (!InstCombiner::canFreelyInvertAllUsersOf(&I, /*IgnoredUser=*/nullptr)) return false; Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not"); Value *NewBinOp = BinaryOperator::Create(NewOpc, X, NotY, I.getName() + ".not"); Builder.Insert(NewBinOp); replaceInstUsesWith(I, NewBinOp); // We can not just create an outer `not`, it will most likely be immediately // folded back, reconstructing our initial pattern, and causing an // infinite combine loop, so immediately manually fold it away. freelyInvertAllUsersOf(NewBinOp); return true; } Instruction *InstCombinerImpl::foldNot(BinaryOperator &I) { Value *NotOp; if (!match(&I, m_Not(m_Value(NotOp)))) return nullptr; // Apply DeMorgan's Law for 'nand' / 'nor' logic with an inverted operand. // 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) // // Note: The logical matches do not check for the commuted patterns because // those are handled via SimplifySelectsFeedingBinaryOp(). Type *Ty = I.getType(); Value *X, *Y; if (match(NotOp, 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); } if (match(NotOp, m_OneUse(m_LogicalAnd(m_Not(m_Value(X)), m_Value(Y))))) { Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not"); return SelectInst::Create(X, ConstantInt::getTrue(Ty), NotY); } // ~(~X | Y) --> (X & ~Y) // ~(Y | ~X) --> (X & ~Y) if (match(NotOp, 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 (match(NotOp, m_OneUse(m_LogicalOr(m_Not(m_Value(X)), m_Value(Y))))) { Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not"); return SelectInst::Create(X, NotY, ConstantInt::getFalse(Ty)); } // Is this a 'not' (~) fed by a binary operator? BinaryOperator *NotVal; if (match(NotOp, 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 - 1) & (~Y) if (match(NotVal, m_OneUse(m_c_Or(m_OneUse(m_Neg(m_Value(X))), m_Value(Y))))) { Value *DecX = Builder.CreateAdd(X, ConstantInt::getAllOnesValue(Ty)); Value *NotY = Builder.CreateNot(Y); return BinaryOperator::CreateAnd(DecX, NotY); } // ~(~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())) { // We matched a negative constant, so propagating undef is unsafe. // Clamp undef elements to -1. Type *EltTy = Ty->getScalarType(); C = Constant::replaceUndefsWith(C, ConstantInt::getAllOnesValue(EltTy)); 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())) { // We matched a non-negative constant, so propagating undef is unsafe. // Clamp undef elements to 0. Type *EltTy = Ty->getScalarType(); C = Constant::replaceUndefsWith(C, ConstantInt::getNullValue(EltTy)); return BinaryOperator::CreateAShr(ConstantExpr::getNot(C), Y); } // ~(X + C) --> ~C - X if (match(NotVal, m_c_Add(m_Value(X), m_ImmConstant(C)))) return BinaryOperator::CreateSub(ConstantExpr::getNot(C), X); // ~(X - Y) --> ~X + Y // FIXME: is it really beneficial to sink the `not` here? if (match(NotVal, m_Sub(m_Value(X), m_Value(Y)))) if (isa(X) || NotVal->hasOneUse()) return BinaryOperator::CreateAdd(Builder.CreateNot(X), Y); // ~(~X + Y) --> X - Y if (match(NotVal, m_c_Add(m_Not(m_Value(X)), m_Value(Y)))) return BinaryOperator::CreateWithCopiedFlags(Instruction::Sub, X, Y, NotVal); } // not (cmp A, B) = !cmp A, B CmpInst::Predicate Pred; if (match(NotOp, m_OneUse(m_Cmp(Pred, m_Value(), m_Value())))) { cast(NotOp)->setPredicate(CmpInst::getInversePredicate(Pred)); return replaceInstUsesWith(I, NotOp); } // Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max: // ~min(~X, ~Y) --> max(X, Y) // ~max(~X, Y) --> min(X, ~Y) auto *II = dyn_cast(NotOp); if (II && II->hasOneUse()) { if (match(NotOp, m_MaxOrMin(m_Value(X), m_Value(Y))) && isFreeToInvert(X, X->hasOneUse()) && isFreeToInvert(Y, Y->hasOneUse())) { Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID()); Value *NotX = Builder.CreateNot(X); Value *NotY = Builder.CreateNot(Y); Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, NotX, NotY); return replaceInstUsesWith(I, InvMaxMin); } if (match(NotOp, m_c_MaxOrMin(m_Not(m_Value(X)), m_Value(Y)))) { Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID()); Value *NotY = Builder.CreateNot(Y); Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, X, NotY); return replaceInstUsesWith(I, InvMaxMin); } } // TODO: Remove folds if we canonicalize to intrinsics (see above). // 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 (NotOp->hasOneUse()) { Value *LHS, *RHS; SelectPatternFlavor SPF = matchSelectPattern(NotOp, 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); } } // Pull 'not' into operands of select if both operands are one-use compares // or one is one-use compare and the other one is a constant. // Inverting the predicates eliminates the 'not' operation. // Example: // not (select ?, (cmp TPred, ?, ?), (cmp FPred, ?, ?) --> // select ?, (cmp InvTPred, ?, ?), (cmp InvFPred, ?, ?) // not (select ?, (cmp TPred, ?, ?), true --> // select ?, (cmp InvTPred, ?, ?), false if (auto *Sel = dyn_cast(NotOp)) { Value *TV = Sel->getTrueValue(); Value *FV = Sel->getFalseValue(); auto *CmpT = dyn_cast(TV); auto *CmpF = dyn_cast(FV); bool InvertibleT = (CmpT && CmpT->hasOneUse()) || isa(TV); bool InvertibleF = (CmpF && CmpF->hasOneUse()) || isa(FV); if (InvertibleT && InvertibleF) { if (CmpT) CmpT->setPredicate(CmpT->getInversePredicate()); else Sel->setTrueValue(ConstantExpr::getNot(cast(TV))); if (CmpF) CmpF->setPredicate(CmpF->getInversePredicate()); else Sel->setFalseValue(ConstantExpr::getNot(cast(FV))); return replaceInstUsesWith(I, Sel); } } } if (Instruction *NewXor = sinkNotIntoXor(I, Builder)) return NewXor; 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 *InstCombinerImpl::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 *Phi = foldBinopWithPhiOperands(I)) return Phi; 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); if (Instruction *R = foldNot(I)) return R; // 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 *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 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); if (Instruction *Xor = visitMaskedMerge(I, Builder)) return Xor; Value *X, *Y; Constant *C1; if (match(Op1, m_Constant(C1))) { // Use DeMorgan and reassociation to eliminate a 'not' op. 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)); } // Convert xor ([trunc] (ashr X, BW-1)), C => // select(X >s -1, C, ~C) // The ashr creates "AllZeroOrAllOne's", which then optionally inverses the // constant depending on whether this input is less than 0. const APInt *CA; if (match(Op0, m_OneUse(m_TruncOrSelf( m_AShr(m_Value(X), m_APIntAllowUndef(CA))))) && *CA == X->getType()->getScalarSizeInBits() - 1 && !match(C1, m_AllOnes())) { assert(!C1->isZeroValue() && "Unexpected xor with 0"); Value *ICmp = Builder.CreateICmpSGT(X, Constant::getAllOnesValue(X->getType())); return SelectInst::Create(ICmp, Op1, Builder.CreateNot(Op1)); } } Type *Ty = I.getType(); { const APInt *RHSC; if (match(Op1, m_APInt(RHSC))) { Value *X; const APInt *C; // (C - X) ^ signmaskC --> (C + signmaskC) - X if (RHSC->isSignMask() && match(Op0, m_Sub(m_APInt(C), m_Value(X)))) return BinaryOperator::CreateSub(ConstantInt::get(Ty, *C + *RHSC), X); // (X + C) ^ signmaskC --> X + (C + signmaskC) if (RHSC->isSignMask() && match(Op0, m_Add(m_Value(X), m_APInt(C)))) return BinaryOperator::CreateAdd(X, ConstantInt::get(Ty, *C + *RHSC)); // (X | C) ^ RHSC --> X ^ (C ^ RHSC) iff X & C == 0 if (match(Op0, m_Or(m_Value(X), m_APInt(C))) && MaskedValueIsZero(X, *C, 0, &I)) return BinaryOperator::CreateXor(X, ConstantInt::get(Ty, *C ^ *RHSC)); // If RHSC is inverting the remaining bits of shifted X, // canonicalize to a 'not' before the shift to help SCEV and codegen: // (X << C) ^ RHSC --> ~X << C if (match(Op0, m_OneUse(m_Shl(m_Value(X), m_APInt(C)))) && *RHSC == APInt::getAllOnes(Ty->getScalarSizeInBits()).shl(*C)) { Value *NotX = Builder.CreateNot(X); return BinaryOperator::CreateShl(NotX, ConstantInt::get(Ty, *C)); } // (X >>u C) ^ RHSC --> ~X >>u C if (match(Op0, m_OneUse(m_LShr(m_Value(X), m_APInt(C)))) && *RHSC == APInt::getAllOnes(Ty->getScalarSizeInBits()).lshr(*C)) { Value *NotX = Builder.CreateNot(X); return BinaryOperator::CreateLShr(NotX, ConstantInt::get(Ty, *C)); } // TODO: We could handle 'ashr' here as well. That would be matching // a 'not' op and moving it before the shift. Doing that requires // preventing the inverse fold in canShiftBinOpWithConstantRHS(). } } // FIXME: This should not be limited to scalar (pull into APInt match above). { Value *X; ConstantInt *C1, *C2, *C3; // ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3) if (match(Op1, m_ConstantInt(C3)) && match(Op0, m_LShr(m_Xor(m_Value(X), m_ConstantInt(C1)), m_ConstantInt(C2))) && Op0->hasOneUse()) { // fold (C1 >> C2) ^ C3 APInt FoldConst = C1->getValue().lshr(C2->getValue()); FoldConst ^= C3->getValue(); // Prepare the two operands. auto *Opnd0 = cast(Builder.CreateLShr(X, C2)); Opnd0->takeName(cast(Op0)); Opnd0->setDebugLoc(I.getDebugLoc()); return BinaryOperator::CreateXor(Opnd0, ConstantInt::get(Ty, FoldConst)); } } 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)); // (~A & B) ^ A --> A | B -- There are 4 commuted variants. if (match(&I, m_c_Xor(m_c_And(m_Not(m_Value(A)), m_Value(B)), m_Deferred(A)))) return BinaryOperator::CreateOr(A, B); // (~A | B) ^ A --> ~(A & B) if (match(Op0, m_OneUse(m_c_Or(m_Not(m_Specific(Op1)), m_Value(B))))) return BinaryOperator::CreateNot(Builder.CreateAnd(Op1, B)); // A ^ (~A | B) --> ~(A & B) if (match(Op1, m_OneUse(m_c_Or(m_Not(m_Specific(Op0)), m_Value(B))))) return BinaryOperator::CreateNot(Builder.CreateAnd(Op0, B)); // (A | B) ^ (A | C) --> (B ^ C) & ~A -- There are 4 commuted variants. // TODO: Loosen one-use restriction if common operand is a constant. Value *D; if (match(Op0, m_OneUse(m_Or(m_Value(A), m_Value(B)))) && match(Op1, m_OneUse(m_Or(m_Value(C), m_Value(D))))) { if (B == C || B == D) std::swap(A, B); if (A == C) std::swap(C, D); if (A == D) { Value *NotA = Builder.CreateNot(A); return BinaryOperator::CreateAnd(Builder.CreateXor(B, C), NotA); } } if (auto *LHS = dyn_cast(I.getOperand(0))) if (auto *RHS = dyn_cast(I.getOperand(1))) if (Value *V = foldXorOfICmps(LHS, RHS, I)) return replaceInstUsesWith(I, V); if (Instruction *CastedXor = foldCastedBitwiseLogic(I)) return CastedXor; if (Instruction *Abs = canonicalizeAbs(I, Builder)) return Abs; // Otherwise, if all else failed, try to hoist the xor-by-constant: // (X ^ C) ^ Y --> (X ^ Y) ^ C // Just like we do in other places, we completely avoid the fold // for constantexprs, at least to avoid endless combine loop. if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_CombineAnd(m_Value(X), m_Unless(m_ConstantExpr())), m_ImmConstant(C1))), m_Value(Y)))) return BinaryOperator::CreateXor(Builder.CreateXor(X, Y), C1); return nullptr; }