//===- InstCombineAndOrXor.cpp --------------------------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the visitAnd, visitOr, and visitXor functions. // //===----------------------------------------------------------------------===// #include "InstCombineInternal.h" #include "llvm/Analysis/InstructionSimplify.h" #include "llvm/IR/ConstantRange.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/PatternMatch.h" #include "llvm/Transforms/Utils/CmpInstAnalysis.h" #include "llvm/Transforms/Utils/Local.h" using namespace llvm; using namespace PatternMatch; #define DEBUG_TYPE "instcombine" static inline Value *dyn_castNotVal(Value *V) { // If this is not(not(x)) don't return that this is a not: we want the two // not's to be folded first. if (BinaryOperator::isNot(V)) { Value *Operand = BinaryOperator::getNotArgument(V); if (!IsFreeToInvert(Operand, Operand->hasOneUse())) return Operand; } // Constants can be considered to be not'ed values... if (ConstantInt *C = dyn_cast(V)) return ConstantInt::get(C->getType(), ~C->getValue()); return nullptr; } /// 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(bool Sign, unsigned Code, Value *LHS, Value *RHS, InstCombiner::BuilderTy *Builder) { ICmpInst::Predicate NewPred; if (Value *NewConstant = getICmpValue(Sign, Code, LHS, RHS, NewPred)) return NewConstant; 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); } /// \brief Transform BITWISE_OP(BSWAP(A),BSWAP(B)) 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. Value *InstCombiner::SimplifyBSwap(BinaryOperator &I) { IntegerType *ITy = dyn_cast(I.getType()); // Can't do vectors. if (I.getType()->isVectorTy()) return nullptr; // Can only do bitwise ops. if (!I.isBitwiseLogicOp()) return nullptr; Value *OldLHS = I.getOperand(0); Value *OldRHS = I.getOperand(1); ConstantInt *ConstLHS = dyn_cast(OldLHS); ConstantInt *ConstRHS = dyn_cast(OldRHS); IntrinsicInst *IntrLHS = dyn_cast(OldLHS); IntrinsicInst *IntrRHS = dyn_cast(OldRHS); bool IsBswapLHS = (IntrLHS && IntrLHS->getIntrinsicID() == Intrinsic::bswap); bool IsBswapRHS = (IntrRHS && IntrRHS->getIntrinsicID() == Intrinsic::bswap); if (!IsBswapLHS && !IsBswapRHS) return nullptr; if (!IsBswapLHS && !ConstLHS) return nullptr; if (!IsBswapRHS && !ConstRHS) return nullptr; /// OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) ) /// OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) ) Value *NewLHS = IsBswapLHS ? IntrLHS->getOperand(0) : Builder->getInt(ConstLHS->getValue().byteSwap()); Value *NewRHS = IsBswapRHS ? IntrRHS->getOperand(0) : Builder->getInt(ConstRHS->getValue().byteSwap()); Value *BinOp = Builder->CreateBinOp(I.getOpcode(), NewLHS, NewRHS); Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::bswap, ITy); return Builder->CreateCall(F, BinOp); } /// This handles expressions of the form ((val OP C1) & C2). Where /// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Instruction *InstCombiner::OptAndOp(BinaryOperator *Op, ConstantInt *OpRHS, ConstantInt *AndRHS, BinaryOperator &TheAnd) { Value *X = Op->getOperand(0); Constant *Together = nullptr; if (!Op->isShift()) Together = ConstantExpr::getAnd(AndRHS, OpRHS); switch (Op->getOpcode()) { default: break; case Instruction::Xor: if (Op->hasOneUse()) { // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) Value *And = Builder->CreateAnd(X, AndRHS); And->takeName(Op); return BinaryOperator::CreateXor(And, Together); } break; case Instruction::Or: if (Op->hasOneUse()){ ConstantInt *TogetherCI = dyn_cast(Together); if (TogetherCI && !TogetherCI->isZero()){ // (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1 // NOTE: This reduces the number of bits set in the & mask, which // can expose opportunities for store narrowing. Together = ConstantExpr::getXor(AndRHS, Together); Value *And = Builder->CreateAnd(X, Together); And->takeName(Op); return BinaryOperator::CreateOr(And, OpRHS); } } break; case Instruction::Add: if (Op->hasOneUse()) { // Adding a one to a single bit bit-field should be turned into an XOR // of the bit. First thing to check is to see if this AND is with a // single bit constant. const APInt &AndRHSV = AndRHS->getValue(); // If there is only one bit set. if (AndRHSV.isPowerOf2()) { // Ok, at this point, we know that we are masking the result of the // ADD down to exactly one bit. If the constant we are adding has // no bits set below this bit, then we can eliminate the ADD. const APInt& AddRHS = OpRHS->getValue(); // Check to see if any bits below the one bit set in AndRHSV are set. if ((AddRHS & (AndRHSV-1)) == 0) { // If not, the only thing that can effect the output of the AND is // the bit specified by AndRHSV. If that bit is set, the effect of // the XOR is to toggle the bit. If it is clear, then the ADD has // no effect. if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop TheAnd.setOperand(0, X); return &TheAnd; } else { // Pull the XOR out of the AND. Value *NewAnd = Builder->CreateAnd(X, AndRHS); NewAnd->takeName(Op); return BinaryOperator::CreateXor(NewAnd, AndRHS); } } } } break; case Instruction::Shl: { // We know that the AND will not produce any of the bits shifted in, so if // the anded constant includes them, clear them now! // uint32_t BitWidth = AndRHS->getType()->getBitWidth(); uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal)); ConstantInt *CI = Builder->getInt(AndRHS->getValue() & ShlMask); if (CI->getValue() == ShlMask) // Masking out bits that the shift already masks. return replaceInstUsesWith(TheAnd, Op); // No need for the and. if (CI != AndRHS) { // Reducing bits set in and. TheAnd.setOperand(1, CI); return &TheAnd; } break; } case Instruction::LShr: { // We know that the AND will not produce any of the bits shifted in, so if // the anded constant includes them, clear them now! This only applies to // unsigned shifts, because a signed shr may bring in set bits! // uint32_t BitWidth = AndRHS->getType()->getBitWidth(); uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); ConstantInt *CI = Builder->getInt(AndRHS->getValue() & ShrMask); if (CI->getValue() == ShrMask) // Masking out bits that the shift already masks. return replaceInstUsesWith(TheAnd, Op); if (CI != AndRHS) { TheAnd.setOperand(1, CI); // Reduce bits set in and cst. return &TheAnd; } break; } case Instruction::AShr: // Signed shr. // See if this is shifting in some sign extension, then masking it out // with an and. if (Op->hasOneUse()) { uint32_t BitWidth = AndRHS->getType()->getBitWidth(); uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); Constant *C = Builder->getInt(AndRHS->getValue() & ShrMask); if (C == AndRHS) { // Masking out bits shifted in. // (Val ashr C1) & C2 -> (Val lshr C1) & C2 // Make the argument unsigned. Value *ShVal = Op->getOperand(0); ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName()); return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName()); } } break; } return nullptr; } /// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise /// (V < Lo || V >= Hi). This method expects that Lo <= Hi. IsSigned indicates /// whether to treat V, Lo, and Hi as signed or not. Value *InstCombiner::insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi, bool isSigned, bool Inside) { assert((isSigned ? Lo.sle(Hi) : Lo.ule(Hi)) && "Lo is not <= Hi in range emission code!"); Type *Ty = V->getType(); if (Lo == Hi) return Inside ? ConstantInt::getFalse(Ty) : ConstantInt::getTrue(Ty); // V >= Min && V < Hi --> V < Hi // V < Min || V >= Hi --> V >= Hi ICmpInst::Predicate Pred = Inside ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_UGE; if (isSigned ? Lo.isMinSignedValue() : Lo.isMinValue()) { Pred = isSigned ? ICmpInst::getSignedPredicate(Pred) : Pred; return Builder->CreateICmp(Pred, V, ConstantInt::get(Ty, Hi)); } // V >= Lo && V < Hi --> V - Lo u< Hi - Lo // V < Lo || V >= Hi --> V - Lo u>= Hi - Lo Value *VMinusLo = Builder->CreateSub(V, ConstantInt::get(Ty, Lo), V->getName() + ".off"); Constant *HiMinusLo = ConstantInt::get(Ty, Hi - Lo); return Builder->CreateICmp(Pred, VMinusLo, HiMinusLo); } /// Classify (icmp eq (A & B), C) and (icmp ne (A & B), C) as matching patterns /// that can be simplified. /// One of A and B is considered the mask. The other is the value. This is /// described as the "AMask" or "BMask" part of the enum. If the enum contains /// only "Mask", then both A and B can be considered masks. If A is the mask, /// then it was proven that (A & C) == C. This is trivial if C == A or C == 0. /// If both A and C are constants, this proof is also easy. /// For the following explanations, we assume that A is the mask. /// /// "AllOnes" declares that the comparison is true only if (A & B) == A or all /// bits of A are set in B. /// Example: (icmp eq (A & 3), 3) -> AMask_AllOnes /// /// "AllZeros" declares that the comparison is true only if (A & B) == 0 or all /// bits of A are cleared in B. /// Example: (icmp eq (A & 3), 0) -> Mask_AllZeroes /// /// "Mixed" declares that (A & B) == C and C might or might not contain any /// number of one bits and zero bits. /// Example: (icmp eq (A & 3), 1) -> AMask_Mixed /// /// "Not" means that in above descriptions "==" should be replaced by "!=". /// Example: (icmp ne (A & 3), 3) -> AMask_NotAllOnes /// /// If the mask A contains a single bit, then the following is equivalent: /// (icmp eq (A & B), A) equals (icmp ne (A & B), 0) /// (icmp ne (A & B), A) equals (icmp eq (A & B), 0) enum MaskedICmpType { AMask_AllOnes = 1, AMask_NotAllOnes = 2, BMask_AllOnes = 4, BMask_NotAllOnes = 8, Mask_AllZeros = 16, Mask_NotAllZeros = 32, AMask_Mixed = 64, AMask_NotMixed = 128, BMask_Mixed = 256, BMask_NotMixed = 512 }; /// Return the set of patterns (from MaskedICmpType) that (icmp SCC (A & B), C) /// satisfies. static unsigned getMaskedICmpType(Value *A, Value *B, Value *C, ICmpInst::Predicate Pred) { ConstantInt *ACst = dyn_cast(A); ConstantInt *BCst = dyn_cast(B); ConstantInt *CCst = dyn_cast(C); bool IsEq = (Pred == ICmpInst::ICMP_EQ); bool IsAPow2 = (ACst && !ACst->isZero() && ACst->getValue().isPowerOf2()); bool IsBPow2 = (BCst && !BCst->isZero() && BCst->getValue().isPowerOf2()); unsigned MaskVal = 0; if (CCst && CCst->isZero()) { // if C is zero, then both A and B qualify as mask MaskVal |= (IsEq ? (Mask_AllZeros | AMask_Mixed | BMask_Mixed) : (Mask_NotAllZeros | AMask_NotMixed | BMask_NotMixed)); if (IsAPow2) MaskVal |= (IsEq ? (AMask_NotAllOnes | AMask_NotMixed) : (AMask_AllOnes | AMask_Mixed)); if (IsBPow2) MaskVal |= (IsEq ? (BMask_NotAllOnes | BMask_NotMixed) : (BMask_AllOnes | BMask_Mixed)); return MaskVal; } if (A == C) { MaskVal |= (IsEq ? (AMask_AllOnes | AMask_Mixed) : (AMask_NotAllOnes | AMask_NotMixed)); if (IsAPow2) MaskVal |= (IsEq ? (Mask_NotAllZeros | AMask_NotMixed) : (Mask_AllZeros | AMask_Mixed)); } else if (ACst && CCst && ConstantExpr::getAnd(ACst, CCst) == CCst) { MaskVal |= (IsEq ? AMask_Mixed : AMask_NotMixed); } if (B == C) { MaskVal |= (IsEq ? (BMask_AllOnes | BMask_Mixed) : (BMask_NotAllOnes | BMask_NotMixed)); if (IsBPow2) MaskVal |= (IsEq ? (Mask_NotAllZeros | BMask_NotMixed) : (Mask_AllZeros | BMask_Mixed)); } else if (BCst && CCst && ConstantExpr::getAnd(BCst, CCst) == CCst) { MaskVal |= (IsEq ? BMask_Mixed : BMask_NotMixed); } return MaskVal; } /// Convert an analysis of a masked ICmp into its equivalent if all boolean /// operations had the opposite sense. Since each "NotXXX" flag (recording !=) /// is adjacent to the corresponding normal flag (recording ==), this just /// involves swapping those bits over. static unsigned conjugateICmpMask(unsigned Mask) { unsigned NewMask; NewMask = (Mask & (AMask_AllOnes | BMask_AllOnes | Mask_AllZeros | AMask_Mixed | BMask_Mixed)) << 1; NewMask |= (Mask & (AMask_NotAllOnes | BMask_NotAllOnes | Mask_NotAllZeros | AMask_NotMixed | BMask_NotMixed)) >> 1; return NewMask; } /// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E). /// Return the set of pattern classes (from MaskedICmpType) that both LHS and /// RHS satisfy. static unsigned getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C, Value *&D, Value *&E, ICmpInst *LHS, ICmpInst *RHS, ICmpInst::Predicate &PredL, ICmpInst::Predicate &PredR) { if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return 0; // vectors are not (yet?) supported if (LHS->getOperand(0)->getType()->isVectorTy()) return 0; // 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(LHS, PredL, L11, L12, L2)) { L21 = L22 = L1 = nullptr; } else { // Look for ANDs in the LHS icmp. if (!L1->getType()->isIntegerTy()) { // You can icmp pointers, for example. They really aren't masks. L11 = L12 = nullptr; } else 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 (!L2->getType()->isIntegerTy()) { // You can icmp pointers, for example. They really aren't masks. L21 = L22 = nullptr; } else 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 0; Value *R1 = RHS->getOperand(0); Value *R2 = RHS->getOperand(1); Value *R11, *R12; bool Ok = false; if (decomposeBitTestICmp(RHS, 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 0; } E = R2; R1 = nullptr; Ok = true; } else if (R1->getType()->isIntegerTy()) { 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 0; // Look for ANDs on the right side of the RHS icmp. if (!Ok && R2->getType()->isIntegerTy()) { 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 0; } } if (!Ok) return 0; 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 LeftType & RightType; } /// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) /// into a single (icmp(A & X) ==/!= Y). static Value *foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, llvm::InstCombiner::BuilderTy *Builder) { Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr; ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); unsigned Mask = getMaskedTypeForICmpPair(A, B, C, D, E, LHS, RHS, PredL, PredR); if (Mask == 0) return nullptr; assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) && "Expected equality predicates for masked type of icmps."); // In full generality: // (icmp (A & B) Op C) | (icmp (A & D) Op E) // == ![ (icmp (A & B) !Op C) & (icmp (A & D) !Op E) ] // // If the latter can be converted into (icmp (A & X) Op Y) then the former is // equivalent to (icmp (A & X) !Op Y). // // Therefore, we can pretend for the rest of this function that we're dealing // with the conjunction, provided we flip the sense of any comparisons (both // input and output). // In most cases we're going to produce an EQ for the "&&" case. ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE; if (!IsAnd) { // Convert the masking analysis into its equivalent with negated // comparisons. Mask = conjugateICmpMask(Mask); } if (Mask & Mask_AllZeros) { // (icmp eq (A & B), 0) & (icmp eq (A & D), 0) // -> (icmp eq (A & (B|D)), 0) Value *NewOr = Builder->CreateOr(B, D); Value *NewAnd = Builder->CreateAnd(A, NewOr); // We can't use C as zero because we might actually handle // (icmp ne (A & B), B) & (icmp ne (A & D), D) // with B and D, having a single bit set. Value *Zero = Constant::getNullValue(A->getType()); return Builder->CreateICmp(NewCC, NewAnd, Zero); } if (Mask & BMask_AllOnes) { // (icmp eq (A & B), B) & (icmp eq (A & D), D) // -> (icmp eq (A & (B|D)), (B|D)) Value *NewOr = Builder->CreateOr(B, D); Value *NewAnd = Builder->CreateAnd(A, NewOr); return Builder->CreateICmp(NewCC, NewAnd, NewOr); } if (Mask & AMask_AllOnes) { // (icmp eq (A & B), A) & (icmp eq (A & D), A) // -> (icmp eq (A & (B&D)), A) Value *NewAnd1 = Builder->CreateAnd(B, D); Value *NewAnd2 = Builder->CreateAnd(A, NewAnd1); return Builder->CreateICmp(NewCC, NewAnd2, A); } // Remaining cases assume at least that B and D are constant, and depend on // their actual values. This isn't strictly necessary, just a "handle the // easy cases for now" decision. ConstantInt *BCst = dyn_cast(B); if (!BCst) return nullptr; ConstantInt *DCst = dyn_cast(D); if (!DCst) return nullptr; if (Mask & (Mask_NotAllZeros | BMask_NotAllOnes)) { // (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and // (icmp ne (A & B), B) & (icmp ne (A & D), D) // -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0) // Only valid if one of the masks is a superset of the other (check "B&D" is // the same as either B or D). APInt NewMask = BCst->getValue() & DCst->getValue(); if (NewMask == BCst->getValue()) return LHS; else if (NewMask == DCst->getValue()) return RHS; } if (Mask & AMask_NotAllOnes) { // (icmp ne (A & B), B) & (icmp ne (A & D), D) // -> (icmp ne (A & B), A) or (icmp ne (A & D), A) // Only valid if one of the masks is a superset of the other (check "B|D" is // the same as either B or D). APInt NewMask = BCst->getValue() | DCst->getValue(); if (NewMask == BCst->getValue()) return LHS; else if (NewMask == DCst->getValue()) return RHS; } if (Mask & BMask_Mixed) { // (icmp eq (A & B), C) & (icmp eq (A & D), E) // We already know that B & C == C && D & E == E. // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of // C and E, which are shared by both the mask B and the mask D, don't // contradict, then we can transform to // -> (icmp eq (A & (B|D)), (C|E)) // Currently, we only handle the case of B, C, D, and E being constant. // We can't simply use C and E because we might actually handle // (icmp ne (A & B), B) & (icmp eq (A & D), D) // with B and D, having a single bit set. ConstantInt *CCst = dyn_cast(C); if (!CCst) return nullptr; ConstantInt *ECst = dyn_cast(E); if (!ECst) return nullptr; if (PredL != NewCC) CCst = cast(ConstantExpr::getXor(BCst, CCst)); if (PredR != NewCC) ECst = cast(ConstantExpr::getXor(DCst, ECst)); // If there is a conflict, we should actually return a false for the // whole construct. if (((BCst->getValue() & DCst->getValue()) & (CCst->getValue() ^ ECst->getValue())) != 0) return ConstantInt::get(LHS->getType(), !IsAnd); Value *NewOr1 = Builder->CreateOr(B, D); Value *NewOr2 = ConstantExpr::getOr(CCst, ECst); Value *NewAnd = Builder->CreateAnd(A, NewOr1); return Builder->CreateICmp(NewCC, NewAnd, NewOr2); } return nullptr; } /// Try to fold a signed range checked with lower bound 0 to an unsigned icmp. /// Example: (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n /// If \p Inverted is true then the check is for the inverted range, e.g. /// (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n Value *InstCombiner::simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted) { // Check the lower range comparison, e.g. x >= 0 // InstCombine already ensured that if there is a constant it's on the RHS. ConstantInt *RangeStart = dyn_cast(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. bool IsNegative, IsNotNegative; ComputeSignBit(RangeEnd, IsNotNegative, IsNegative, /*Depth=*/0, Cmp1); if (!IsNotNegative) return nullptr; if (Inverted) NewPred = ICmpInst::getInversePredicate(NewPred); return Builder->CreateICmp(NewPred, Input, RangeEnd); } static Value * foldAndOrOfEqualityCmpsWithConstants(ICmpInst *LHS, ICmpInst *RHS, bool JoinedByAnd, InstCombiner::BuilderTy *Builder) { Value *X = LHS->getOperand(0); if (X != RHS->getOperand(0)) return nullptr; const APInt *C1, *C2; if (!match(LHS->getOperand(1), m_APInt(C1)) || !match(RHS->getOperand(1), m_APInt(C2))) return nullptr; // We only handle (X != C1 && X != C2) and (X == C1 || X == C2). ICmpInst::Predicate Pred = LHS->getPredicate(); if (Pred != RHS->getPredicate()) return nullptr; if (JoinedByAnd && Pred != ICmpInst::ICMP_NE) return nullptr; if (!JoinedByAnd && Pred != ICmpInst::ICMP_EQ) return nullptr; // The larger unsigned constant goes on the right. if (C1->ugt(*C2)) std::swap(C1, C2); APInt Xor = *C1 ^ *C2; if (Xor.isPowerOf2()) { // If LHSC and RHSC differ by only one bit, then set that bit in X and // compare against the larger constant: // (X == C1 || X == C2) --> (X | (C1 ^ C2)) == C2 // (X != C1 && X != C2) --> (X | (C1 ^ C2)) != C2 // We choose an 'or' with a Pow2 constant rather than the inverse mask with // 'and' because that may lead to smaller codegen from a smaller constant. Value *Or = Builder->CreateOr(X, ConstantInt::get(X->getType(), Xor)); return Builder->CreateICmp(Pred, Or, ConstantInt::get(X->getType(), *C2)); } // Special case: get the ordering right when the values wrap around zero. // Ie, we assumed the constants were unsigned when swapping earlier. if (*C1 == 0 && C2->isAllOnesValue()) std::swap(C1, C2); if (*C1 == *C2 - 1) { // (X == 13 || X == 14) --> X - 13 <=u 1 // (X != 13 && X != 14) --> X - 13 >u 1 // An 'add' is the canonical IR form, so favor that over a 'sub'. Value *Add = Builder->CreateAdd(X, ConstantInt::get(X->getType(), -(*C1))); auto NewPred = JoinedByAnd ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_ULE; return Builder->CreateICmp(NewPred, Add, ConstantInt::get(X->getType(), 1)); } return nullptr; } /// Fold (icmp)&(icmp) if possible. Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) { 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(isSigned, Code, Op0, Op1, Builder); } } // handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E) if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, true, Builder)) return V; // E.g. (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/false)) return V; // E.g. (icmp slt x, n) & (icmp sge x, 0) --> icmp ult x, n if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/false)) return V; if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, true, Builder)) return V; // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2). Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0); ConstantInt *LHSC = dyn_cast(LHS->getOperand(1)); ConstantInt *RHSC = dyn_cast(RHS->getOperand(1)); if (!LHSC || !RHSC) return nullptr; if (LHSC == RHSC && PredL == PredR) { // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C) // where C is a power of 2 or // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0) if ((PredL == ICmpInst::ICMP_ULT && LHSC->getValue().isPowerOf2()) || (PredL == ICmpInst::ICMP_EQ && LHSC->isZero())) { Value *NewOr = Builder->CreateOr(LHS0, RHS0); return Builder->CreateICmp(PredL, NewOr, LHSC); } } // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2 // where CMAX is the all ones value for the truncated type, // iff the lower bits of C2 and CA are zero. if (PredL == ICmpInst::ICMP_EQ && PredL == PredR && LHS->hasOneUse() && RHS->hasOneUse()) { Value *V; ConstantInt *AndC, *SmallC = nullptr, *BigC = nullptr; // (trunc x) == C1 & (and x, CA) == C2 // (and x, CA) == C2 & (trunc x) == C1 if (match(RHS0, m_Trunc(m_Value(V))) && match(LHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) { SmallC = RHSC; BigC = LHSC; } else if (match(LHS0, m_Trunc(m_Value(V))) && match(RHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) { SmallC = LHSC; BigC = RHSC; } if (SmallC && BigC) { unsigned BigBitSize = BigC->getType()->getBitWidth(); unsigned SmallBitSize = SmallC->getType()->getBitWidth(); // Check that the low bits are zero. APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize); if ((Low & AndC->getValue()) == 0 && (Low & BigC->getValue()) == 0) { Value *NewAnd = Builder->CreateAnd(V, Low | AndC->getValue()); APInt N = SmallC->getValue().zext(BigBitSize) | BigC->getValue(); Value *NewVal = ConstantInt::get(AndC->getType()->getContext(), N); return Builder->CreateICmp(PredL, NewAnd, NewVal); } } } // From here on, we only handle: // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler. if (LHS0 != RHS0) return nullptr; // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere. if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE || PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE || PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE || PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE) return nullptr; // We can't fold (ugt x, C) & (sgt x, C2). if (!PredicatesFoldable(PredL, PredR)) return nullptr; // Ensure that the larger constant is on the RHS. bool ShouldSwap; if (CmpInst::isSigned(PredL) || (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR))) ShouldSwap = LHSC->getValue().sgt(RHSC->getValue()); else ShouldSwap = LHSC->getValue().ugt(RHSC->getValue()); if (ShouldSwap) { std::swap(LHS, RHS); std::swap(LHSC, RHSC); std::swap(PredL, PredR); } // At this point, we know we have two icmp instructions // comparing a value against two constants and and'ing the result // together. Because of the above check, we know that we only have // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know // (from the icmp folding check above), that the two constants // are not equal and that the larger constant is on the RHS assert(LHSC != RHSC && "Compares not folded above?"); switch (PredL) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13 return LHS; } case ICmpInst::ICMP_NE: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_ULT: if (LHSC == SubOne(RHSC)) // (X != 13 & X u< 14) -> X < 13 return Builder->CreateICmpULT(LHS0, LHSC); if (LHSC->isNullValue()) // (X != 0 & X u< 14) -> X-1 u< 13 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), false, true); break; // (X != 13 & X u< 15) -> no change case ICmpInst::ICMP_SLT: if (LHSC == SubOne(RHSC)) // (X != 13 & X s< 14) -> X < 13 return Builder->CreateICmpSLT(LHS0, LHSC); break; // (X != 13 & X s< 15) -> no change case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15 return RHS; case ICmpInst::ICMP_NE: // Potential folds for this case should already be handled. break; } break; case ICmpInst::ICMP_ULT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0); case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13 return LHS; } break; case ICmpInst::ICMP_SLT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13 return LHS; } break; case ICmpInst::ICMP_UGT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15 return RHS; case ICmpInst::ICMP_NE: if (RHSC == AddOne(LHSC)) // (X u> 13 & X != 14) -> X u> 14 return Builder->CreateICmp(PredL, LHS0, RHSC); break; // (X u> 13 & X != 15) -> no change case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) getValue() + 1, RHSC->getValue(), false, true); } break; case ICmpInst::ICMP_SGT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15 return RHS; case ICmpInst::ICMP_NE: if (RHSC == AddOne(LHSC)) // (X s> 13 & X != 14) -> X s> 14 return Builder->CreateICmp(PredL, LHS0, RHSC); break; // (X s> 13 & X != 15) -> no change case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true, true); } break; } return nullptr; } /// Optimize (fcmp)&(fcmp). NOTE: Unlike the rest of instcombine, this returns /// a Value which should already be inserted into the function. Value *InstCombiner::FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS) { Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1); Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1); FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate(); if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { // Swap RHS operands to match LHS. Op1CC = FCmpInst::getSwappedPredicate(Op1CC); std::swap(Op1LHS, Op1RHS); } // 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 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) return getFCmpValue(getFCmpCode(Op0CC) & getFCmpCode(Op1CC), Op0LHS, Op0RHS, Builder); if (LHS->getPredicate() == FCmpInst::FCMP_ORD && RHS->getPredicate() == FCmpInst::FCMP_ORD) { if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return nullptr; // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y) if (ConstantFP *LHSC = dyn_cast(LHS->getOperand(1))) if (ConstantFP *RHSC = dyn_cast(RHS->getOperand(1))) { // If either of the constants are nans, then the whole thing returns // false. if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) return Builder->getFalse(); return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0)); } // Handle vector zeros. This occurs because the canonical form of // "fcmp ord x,x" is "fcmp ord x, 0". if (isa(LHS->getOperand(1)) && isa(RHS->getOperand(1))) return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0)); return nullptr; } return nullptr; } /// Match De Morgan's Laws: /// (~A & ~B) == (~(A | B)) /// (~A | ~B) == (~(A & B)) static Instruction *matchDeMorgansLaws(BinaryOperator &I, InstCombiner::BuilderTy *Builder) { auto Opcode = I.getOpcode(); assert((Opcode == Instruction::And || Opcode == Instruction::Or) && "Trying to match De Morgan's Laws with something other than and/or"); // Flip the logic operation. if (Opcode == Instruction::And) Opcode = Instruction::Or; else Opcode = Instruction::And; Value *Op0 = I.getOperand(0); Value *Op1 = I.getOperand(1); // TODO: Use pattern matchers instead of dyn_cast. if (Value *Op0NotVal = dyn_castNotVal(Op0)) if (Value *Op1NotVal = dyn_castNotVal(Op1)) if (Op0->hasOneUse() && Op1->hasOneUse()) { Value *LogicOp = Builder->CreateBinOp(Opcode, Op0NotVal, Op1NotVal, I.getName() + ".demorgan"); return BinaryOperator::CreateNot(LogicOp); } return nullptr; } bool InstCombiner::shouldOptimizeCast(CastInst *CI) { Value *CastSrc = CI->getOperand(0); // Noop casts and casts of constants should be eliminated trivially. if (CI->getSrcTy() == CI->getDestTy() || isa(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; // If this is a vector sext from a compare, then we don't want to break the // idiom where each element of the extended vector is either zero or all ones. if (CI->getOpcode() == Instruction::SExt && isa(CastSrc) && CI->getDestTy()->isVectorTy()) return false; return true; } /// Fold {and,or,xor} (cast X), C. static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast, InstCombiner::BuilderTy *Builder) { Constant *C; if (!match(Logic.getOperand(1), m_Constant(C))) return nullptr; auto LogicOpc = Logic.getOpcode(); Type *DestTy = Logic.getType(); Type *SrcTy = Cast->getSrcTy(); // If the first operand is bitcast, move the logic operation ahead of the // bitcast (do the logic operation in the original type). This can eliminate // bitcasts and allow combines that would otherwise be impeded by the bitcast. Value *X; if (match(Cast, m_BitCast(m_Value(X)))) { Value *NewConstant = ConstantExpr::getBitCast(C, SrcTy); Value *NewOp = Builder->CreateBinOp(LogicOpc, X, NewConstant); return CastInst::CreateBitOrPointerCast(NewOp, DestTy); } // Similarly, move the logic operation ahead of a zext 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). 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); } } return nullptr; } /// Fold {and,or,xor} (cast X), Y. Instruction *InstCombiner::foldCastedBitwiseLogic(BinaryOperator &I) { auto LogicOpc = I.getOpcode(); assert(I.isBitwiseLogicOp() && "Unexpected opcode for bitwise logic folding"); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); CastInst *Cast0 = dyn_cast(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) : 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) { Value *Res = LogicOpc == Instruction::And ? FoldAndOfFCmps(FCmp0, FCmp1) : FoldOrOfFCmps(FCmp0, FCmp1); if (Res) return CastInst::Create(CastOpcode, Res, DestTy); return nullptr; } return nullptr; } static Instruction *foldBoolSextMaskToSelect(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Canonicalize SExt or Not to the LHS if (match(Op1, m_SExt(m_Value())) || match(Op1, m_Not(m_Value()))) { std::swap(Op0, Op1); } // Fold (and (sext bool to A), B) --> (select bool, B, 0) Value *X = nullptr; if (match(Op0, m_SExt(m_Value(X))) && X->getType()->getScalarType()->isIntegerTy(1)) { Value *Zero = Constant::getNullValue(Op1->getType()); return SelectInst::Create(X, Op1, Zero); } // Fold (and ~(sext bool to A), B) --> (select bool, 0, B) if (match(Op0, m_Not(m_SExt(m_Value(X)))) && X->getType()->getScalarType()->isIntegerTy(1)) { Value *Zero = Constant::getNullValue(Op0->getType()); return SelectInst::Create(X, Zero, Op1); } return nullptr; } // FIXME: We use commutative matchers (m_c_*) for some, but not all, matches // here. We should standardize that construct where it is needed or choose some // other way to ensure that commutated variants of patterns are not missed. Instruction *InstCombiner::visitAnd(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Value *V = SimplifyVectorOp(I)) return replaceInstUsesWith(I, V); if (Value *V = SimplifyAndInst(Op0, Op1, DL, &TLI, &DT, &AC)) return replaceInstUsesWith(I, V); // (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)) return replaceInstUsesWith(I, V); if (ConstantInt *AndRHS = dyn_cast(Op1)) { const APInt &AndRHSMask = AndRHS->getValue(); // Optimize a variety of ((val OP C1) & C2) combinations... if (BinaryOperator *Op0I = dyn_cast(Op0)) { Value *Op0LHS = Op0I->getOperand(0); Value *Op0RHS = Op0I->getOperand(1); switch (Op0I->getOpcode()) { default: break; case Instruction::Xor: case Instruction::Or: { // If the mask is only needed on one incoming arm, push it up. if (!Op0I->hasOneUse()) break; APInt NotAndRHS(~AndRHSMask); if (MaskedValueIsZero(Op0LHS, NotAndRHS, 0, &I)) { // Not masking anything out for the LHS, move to RHS. Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS, Op0RHS->getName()+".masked"); return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS); } if (!isa(Op0RHS) && MaskedValueIsZero(Op0RHS, NotAndRHS, 0, &I)) { // Not masking anything out for the RHS, move to LHS. Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS, Op0LHS->getName()+".masked"); return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS); } break; } case Instruction::Sub: // -x & 1 -> x & 1 if (AndRHSMask == 1 && match(Op0LHS, m_Zero())) return BinaryOperator::CreateAnd(Op0RHS, AndRHS); break; case Instruction::Shl: case Instruction::LShr: // (1 << x) & 1 --> zext(x == 0) // (1 >> x) & 1 --> zext(x == 0) if (AndRHSMask == 1 && Op0LHS == AndRHS) { Value *NewICmp = Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType())); return new ZExtInst(NewICmp, I.getType()); } break; } // ((C1 OP zext(X)) & C2) -> zext((C1-X) & C2) if C2 fits in the bitwidth // of X and OP behaves well when given trunc(C1) and X. switch (Op0I->getOpcode()) { default: break; case Instruction::Xor: case Instruction::Or: case Instruction::Mul: case Instruction::Add: case Instruction::Sub: Value *X; ConstantInt *C1; if (match(Op0I, m_c_BinOp(m_ZExt(m_Value(X)), m_ConstantInt(C1)))) { if (AndRHSMask.isIntN(X->getType()->getScalarSizeInBits())) { auto *TruncC1 = ConstantExpr::getTrunc(C1, X->getType()); Value *BinOp; if (isa(Op0LHS)) BinOp = Builder->CreateBinOp(Op0I->getOpcode(), X, TruncC1); else BinOp = Builder->CreateBinOp(Op0I->getOpcode(), TruncC1, X); auto *TruncC2 = ConstantExpr::getTrunc(AndRHS, X->getType()); auto *And = Builder->CreateAnd(BinOp, TruncC2); return new ZExtInst(And, I.getType()); } } } if (ConstantInt *Op0CI = dyn_cast(Op0I->getOperand(1))) if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I)) return Res; } // If this is an integer truncation, and if the source is an 'and' with // immediate, transform it. This frequently occurs for bitfield accesses. { Value *X = nullptr; ConstantInt *YC = nullptr; if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) { // Change: and (trunc (and X, YC) to T), C2 // into : and (trunc X to T), trunc(YC) & C2 // This will fold the two constants together, which may allow // other simplifications. Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk"); Constant *C3 = ConstantExpr::getTrunc(YC, I.getType()); C3 = ConstantExpr::getAnd(C3, AndRHS); return BinaryOperator::CreateAnd(NewCast, C3); } } } if (isa(Op1)) if (Instruction *FoldedLogic = foldOpWithConstantIntoOperand(I)) return FoldedLogic; if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder)) return DeMorgan; { Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; // (A|B) & ~(A&B) -> A^B if (match(Op0, m_Or(m_Value(A), m_Value(B))) && match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) && ((A == C && B == D) || (A == D && B == C))) return BinaryOperator::CreateXor(A, B); // ~(A&B) & (A|B) -> A^B if (match(Op1, m_Or(m_Value(A), m_Value(B))) && match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) && ((A == C && B == D) || (A == D && B == C))) return BinaryOperator::CreateXor(A, B); // A&(A^B) => A & ~B { Value *tmpOp0 = Op0; Value *tmpOp1 = Op1; if (match(Op0, m_OneUse(m_Xor(m_Value(A), m_Value(B))))) { if (A == Op1 || B == Op1 ) { tmpOp1 = Op0; tmpOp0 = Op1; // Simplify below } } if (match(tmpOp1, m_OneUse(m_Xor(m_Value(A), m_Value(B))))) { if (B == tmpOp0) { std::swap(A, B); } // Notice that the pattern (A&(~B)) is actually (A&(-1^B)), so if // A is originally -1 (or a vector of -1 and undefs), then we enter // an endless loop. By checking that A is non-constant we ensure that // we will never get to the loop. if (A == tmpOp0 && !isa(A)) // A&(A^B) -> A & ~B return BinaryOperator::CreateAnd(A, Builder->CreateNot(B)); } } // (A&((~A)|B)) -> A&B if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) || match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1))))) return BinaryOperator::CreateAnd(A, Op1); if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) || match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0))))) return BinaryOperator::CreateAnd(A, Op0); // (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() || cast(Op1)->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() || cast(Op0)->hasOneUse()) return BinaryOperator::CreateAnd(Op1, Builder->CreateNot(C)); // (A | B) & ((~A) ^ B) -> (A & B) if (match(Op0, m_Or(m_Value(A), m_Value(B))) && match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B)))) return BinaryOperator::CreateAnd(A, B); // ((~A) ^ B) & (A | B) -> (A & B) // ((~A) ^ B) & (B | A) -> (A & B) if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) && match(Op1, m_c_Or(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateAnd(A, B); } { ICmpInst *LHS = dyn_cast(Op0); ICmpInst *RHS = dyn_cast(Op1); if (LHS && RHS) if (Value *Res = FoldAndOfICmps(LHS, RHS)) return replaceInstUsesWith(I, Res); // TODO: Make this recursive; it's a little tricky because an arbitrary // number of 'and' instructions might have to be created. Value *X, *Y; if (LHS && match(Op1, m_OneUse(m_And(m_Value(X), m_Value(Y))))) { if (auto *Cmp = dyn_cast(X)) if (Value *Res = FoldAndOfICmps(LHS, Cmp)) return replaceInstUsesWith(I, Builder->CreateAnd(Res, Y)); if (auto *Cmp = dyn_cast(Y)) if (Value *Res = FoldAndOfICmps(LHS, Cmp)) 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)) return replaceInstUsesWith(I, Builder->CreateAnd(Res, Y)); if (auto *Cmp = dyn_cast(Y)) if (Value *Res = FoldAndOfICmps(Cmp, RHS)) return replaceInstUsesWith(I, Builder->CreateAnd(Res, X)); } } // If and'ing two fcmp, try combine them into one. if (FCmpInst *LHS = dyn_cast(I.getOperand(0))) if (FCmpInst *RHS = dyn_cast(I.getOperand(1))) if (Value *Res = FoldAndOfFCmps(LHS, RHS)) return replaceInstUsesWith(I, Res); if (Instruction *CastedAnd = foldCastedBitwiseLogic(I)) return CastedAnd; if (Instruction *Select = foldBoolSextMaskToSelect(I)) return Select; return Changed ? &I : nullptr; } /// Given an OR instruction, check to see if this is a bswap idiom. If so, /// insert the new intrinsic and return it. Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Look through zero extends. if (Instruction *Ext = dyn_cast(Op0)) Op0 = Ext->getOperand(0); if (Instruction *Ext = dyn_cast(Op1)) Op1 = Ext->getOperand(0); // (A | B) | C and A | (B | C) -> bswap if possible. bool OrOfOrs = match(Op0, m_Or(m_Value(), m_Value())) || match(Op1, m_Or(m_Value(), m_Value())); // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible. bool OrOfShifts = match(Op0, m_LogicalShift(m_Value(), m_Value())) && match(Op1, m_LogicalShift(m_Value(), m_Value())); // (A & B) | (C & D) -> bswap if possible. bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) && match(Op1, m_And(m_Value(), m_Value())); if (!OrOfOrs && !OrOfShifts && !OrOfAnds) return nullptr; SmallVector Insts; if (!recognizeBSwapOrBitReverseIdiom(&I, true, false, Insts)) return nullptr; Instruction *LastInst = Insts.pop_back_val(); LastInst->removeFromParent(); for (auto *Inst : Insts) Worklist.Add(Inst); return LastInst; } /// If all elements of two constant vectors are 0/-1 and inverses, return true. static bool areInverseVectorBitmasks(Constant *C1, Constant *C2) { unsigned NumElts = C1->getType()->getVectorNumElements(); for (unsigned i = 0; i != NumElts; ++i) { Constant *EltC1 = C1->getAggregateElement(i); Constant *EltC2 = C2->getAggregateElement(i); if (!EltC1 || !EltC2) return false; // One element must be all ones, and the other must be all zeros. // FIXME: Allow undef elements. 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. static Value *getSelectCondition(Value *A, Value *B, InstCombiner::BuilderTy &Builder) { // If these are scalars or vectors of i1, A can be used directly. Type *Ty = A->getType(); if (match(A, m_Not(m_Specific(B))) && Ty->getScalarType()->isIntegerTy(1)) return A; // If A and B are sign-extended, look through the sexts to find the booleans. Value *Cond; if (match(A, m_SExt(m_Value(Cond))) && Cond->getType()->getScalarType()->isIntegerTy(1) && match(B, m_CombineOr(m_Not(m_SExt(m_Specific(Cond))), m_SExt(m_Not(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 constants, see if the constants are inverse bitmasks. Constant *AC, *BC; if (match(A, m_Constant(AC)) && match(B, m_Constant(BC)) && areInverseVectorBitmasks(AC, BC)) return ConstantExpr::getTrunc(AC, CmpInst::makeCmpResultType(Ty)); // If both operands are xor'd with constants using the same sexted boolean // operand, see if the constants are inverse bitmasks. if (match(A, (m_Xor(m_SExt(m_Value(Cond)), m_Constant(AC)))) && match(B, (m_Xor(m_SExt(m_Specific(Cond)), m_Constant(BC)))) && Cond->getType()->getScalarType()->isIntegerTy(1) && areInverseVectorBitmasks(AC, BC)) { AC = ConstantExpr::getTrunc(AC, CmpInst::makeCmpResultType(Ty)); return Builder.CreateXor(Cond, AC); } 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. static Value *matchSelectFromAndOr(Value *A, Value *C, Value *B, Value *D, InstCombiner::BuilderTy &Builder) { // 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(); Value *SrcA, *SrcB; if (match(A, m_OneUse(m_BitCast(m_Value(SrcA)))) && match(B, m_OneUse(m_BitCast(m_Value(SrcB))))) { A = SrcA; B = SrcB; } if (Value *Cond = getSelectCondition(A, B, Builder)) { // ((bc Cond) & C) | ((bc ~Cond) & D) --> bc (select Cond, (bc C), (bc D)) // The bitcasts will either all exist or all not exist. The builder will // not create unnecessary casts if the types already match. Value *BitcastC = Builder.CreateBitCast(C, A->getType()); Value *BitcastD = Builder.CreateBitCast(D, A->getType()); Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastD); return Builder.CreateBitCast(Select, OrigType); } return nullptr; } /// Fold (icmp)|(icmp) if possible. Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI) { ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); // Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2) // if K1 and K2 are a one-bit mask. ConstantInt *LHSC = dyn_cast(LHS->getOperand(1)); ConstantInt *RHSC = dyn_cast(RHS->getOperand(1)); if (LHS->getPredicate() == ICmpInst::ICMP_EQ && LHSC && LHSC->isZero() && RHS->getPredicate() == ICmpInst::ICMP_EQ && RHSC && RHSC->isZero()) { BinaryOperator *LAnd = dyn_cast(LHS->getOperand(0)); BinaryOperator *RAnd = dyn_cast(RHS->getOperand(0)); if (LAnd && RAnd && LAnd->hasOneUse() && RHS->hasOneUse() && LAnd->getOpcode() == Instruction::And && RAnd->getOpcode() == Instruction::And) { Value *Mask = nullptr; Value *Masked = nullptr; if (LAnd->getOperand(0) == RAnd->getOperand(0) && isKnownToBeAPowerOfTwo(LAnd->getOperand(1), DL, false, 0, &AC, CxtI, &DT) && isKnownToBeAPowerOfTwo(RAnd->getOperand(1), DL, false, 0, &AC, CxtI, &DT)) { Mask = Builder->CreateOr(LAnd->getOperand(1), RAnd->getOperand(1)); Masked = Builder->CreateAnd(LAnd->getOperand(0), Mask); } else if (LAnd->getOperand(1) == RAnd->getOperand(1) && isKnownToBeAPowerOfTwo(LAnd->getOperand(0), DL, false, 0, &AC, CxtI, &DT) && isKnownToBeAPowerOfTwo(RAnd->getOperand(0), DL, false, 0, &AC, CxtI, &DT)) { Mask = Builder->CreateOr(LAnd->getOperand(0), RAnd->getOperand(0)); Masked = Builder->CreateAnd(LAnd->getOperand(1), Mask); } if (Masked) return Builder->CreateICmp(ICmpInst::ICMP_NE, Masked, Mask); } } // Fold (icmp ult/ule (A + C1), C3) | (icmp ult/ule (A + C2), C3) // --> (icmp ult/ule ((A & ~(C1 ^ C2)) + max(C1, C2)), C3) // The original condition actually refers to the following two ranges: // [MAX_UINT-C1+1, MAX_UINT-C1+1+C3] and [MAX_UINT-C2+1, MAX_UINT-C2+1+C3] // We can fold these two ranges if: // 1) C1 and C2 is unsigned greater than C3. // 2) The two ranges are separated. // 3) C1 ^ C2 is one-bit mask. // 4) LowRange1 ^ LowRange2 and HighRange1 ^ HighRange2 are one-bit mask. // This implies all values in the two ranges differ by exactly one bit. if ((PredL == ICmpInst::ICMP_ULT || PredL == ICmpInst::ICMP_ULE) && PredL == PredR && LHSC && RHSC && LHS->hasOneUse() && RHS->hasOneUse() && LHSC->getType() == RHSC->getType() && LHSC->getValue() == (RHSC->getValue())) { Value *LAdd = LHS->getOperand(0); Value *RAdd = RHS->getOperand(0); Value *LAddOpnd, *RAddOpnd; ConstantInt *LAddC, *RAddC; if (match(LAdd, m_Add(m_Value(LAddOpnd), m_ConstantInt(LAddC))) && match(RAdd, m_Add(m_Value(RAddOpnd), m_ConstantInt(RAddC))) && LAddC->getValue().ugt(LHSC->getValue()) && RAddC->getValue().ugt(LHSC->getValue())) { APInt DiffC = LAddC->getValue() ^ RAddC->getValue(); if (LAddOpnd == RAddOpnd && DiffC.isPowerOf2()) { ConstantInt *MaxAddC = nullptr; if (LAddC->getValue().ult(RAddC->getValue())) MaxAddC = RAddC; else MaxAddC = LAddC; APInt RRangeLow = -RAddC->getValue(); APInt RRangeHigh = RRangeLow + LHSC->getValue(); APInt LRangeLow = -LAddC->getValue(); APInt LRangeHigh = LRangeLow + LHSC->getValue(); APInt LowRangeDiff = RRangeLow ^ LRangeLow; APInt HighRangeDiff = RRangeHigh ^ LRangeHigh; APInt RangeDiff = LRangeLow.sgt(RRangeLow) ? LRangeLow - RRangeLow : RRangeLow - LRangeLow; if (LowRangeDiff.isPowerOf2() && LowRangeDiff == HighRangeDiff && RangeDiff.ugt(LHSC->getValue())) { Value *MaskC = ConstantInt::get(LAddC->getType(), ~DiffC); Value *NewAnd = Builder->CreateAnd(LAddOpnd, MaskC); Value *NewAdd = Builder->CreateAdd(NewAnd, MaxAddC); return (Builder->CreateICmp(LHS->getPredicate(), NewAdd, LHSC)); } } } } // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B) if (PredicatesFoldable(PredL, PredR)) { if (LHS->getOperand(0) == RHS->getOperand(1) && LHS->getOperand(1) == RHS->getOperand(0)) LHS->swapOperands(); if (LHS->getOperand(0) == RHS->getOperand(0) && LHS->getOperand(1) == RHS->getOperand(1)) { Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); unsigned Code = getICmpCode(LHS) | getICmpCode(RHS); bool isSigned = LHS->isSigned() || RHS->isSigned(); return getNewICmpValue(isSigned, Code, Op0, Op1, Builder); } } // handle (roughly): // (icmp ne (A & B), C) | (icmp ne (A & D), E) if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder)) return V; Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0); if (LHS->hasOneUse() || RHS->hasOneUse()) { // (icmp eq B, 0) | (icmp ult A, B) -> (icmp ule A, B-1) // (icmp eq B, 0) | (icmp ugt B, A) -> (icmp ule A, B-1) Value *A = nullptr, *B = nullptr; if (PredL == ICmpInst::ICMP_EQ && LHSC && LHSC->isZero()) { B = LHS0; if (PredR == ICmpInst::ICMP_ULT && LHS0 == RHS->getOperand(1)) A = RHS0; else if (PredR == ICmpInst::ICMP_UGT && LHS0 == RHS0) A = RHS->getOperand(1); } // (icmp ult A, B) | (icmp eq B, 0) -> (icmp ule A, B-1) // (icmp ugt B, A) | (icmp eq B, 0) -> (icmp ule A, B-1) else if (PredR == ICmpInst::ICMP_EQ && RHSC && RHSC->isZero()) { B = RHS0; if (PredL == ICmpInst::ICMP_ULT && RHS0 == LHS->getOperand(1)) A = LHS0; else if (PredL == ICmpInst::ICMP_UGT && LHS0 == RHS0) A = LHS->getOperand(1); } if (A && B) return Builder->CreateICmp( ICmpInst::ICMP_UGE, Builder->CreateAdd(B, ConstantInt::getSigned(B->getType(), -1)), A); } // E.g. (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/true)) return V; // E.g. (icmp sgt x, n) | (icmp slt x, 0) --> icmp ugt x, n if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/true)) return V; if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, false, Builder)) return V; // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2). if (!LHSC || !RHSC) return nullptr; if (LHSC == RHSC && PredL == PredR) { // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0) if (PredL == ICmpInst::ICMP_NE && LHSC->isZero()) { Value *NewOr = Builder->CreateOr(LHS0, RHS0); return Builder->CreateICmp(PredL, NewOr, LHSC); } } // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1) // iff C2 + CA == C1. if (PredL == ICmpInst::ICMP_ULT && PredR == ICmpInst::ICMP_EQ) { ConstantInt *AddC; if (match(LHS0, m_Add(m_Specific(RHS0), m_ConstantInt(AddC)))) if (RHSC->getValue() + AddC->getValue() == LHSC->getValue()) return Builder->CreateICmpULE(LHS0, LHSC); } // From here on, we only handle: // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler. if (LHS0 != RHS0) return nullptr; // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere. if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE || PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE || PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE || PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE) return nullptr; // We can't fold (ugt x, C) | (sgt x, C2). if (!PredicatesFoldable(PredL, PredR)) return nullptr; // Ensure that the larger constant is on the RHS. bool ShouldSwap; if (CmpInst::isSigned(PredL) || (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR))) ShouldSwap = LHSC->getValue().sgt(RHSC->getValue()); else ShouldSwap = LHSC->getValue().ugt(RHSC->getValue()); if (ShouldSwap) { std::swap(LHS, RHS); std::swap(LHSC, RHSC); std::swap(PredL, PredR); } // At this point, we know we have two icmp instructions // comparing a value against two constants and or'ing the result // together. Because of the above check, we know that we only have // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the // icmp folding check above), that the two constants are not // equal. assert(LHSC != RHSC && "Compares not folded above?"); switch (PredL) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // Potential folds for this case should already be handled. break; case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change break; case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15 return RHS; } break; case ICmpInst::ICMP_NE: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13 return LHS; case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true return Builder->getTrue(); } case ICmpInst::ICMP_ULT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change break; case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2 // If RHSC is [us]MAXINT, it is always false. Not handling // this can cause overflow. if (RHSC->isMaxValue(false)) return LHS; return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, false, false); case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15 return RHS; } break; case ICmpInst::ICMP_SLT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change break; case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2 // If RHSC is [us]MAXINT, it is always false. Not handling // this can cause overflow. if (RHSC->isMaxValue(true)) return LHS; return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true, false); case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15 return RHS; } break; case ICmpInst::ICMP_UGT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13 return LHS; case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true return Builder->getTrue(); } break; case ICmpInst::ICMP_SGT: switch (PredR) { default: llvm_unreachable("Unknown integer condition code!"); case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13 return LHS; case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true return Builder->getTrue(); } break; } return nullptr; } /// Optimize (fcmp)|(fcmp). NOTE: Unlike the rest of instcombine, this returns /// a Value which should already be inserted into the function. Value *InstCombiner::FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS) { Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1); Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1); FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate(); if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { // Swap RHS operands to match LHS. Op1CC = FCmpInst::getSwappedPredicate(Op1CC); std::swap(Op1LHS, Op1RHS); } // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y). // This is a similar transformation to the one in FoldAndOfFCmps. // // 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 (Op0LHS == Op1LHS && Op0RHS == Op1RHS) return getFCmpValue(getFCmpCode(Op0CC) | getFCmpCode(Op1CC), Op0LHS, Op0RHS, Builder); if (LHS->getPredicate() == FCmpInst::FCMP_UNO && RHS->getPredicate() == FCmpInst::FCMP_UNO && LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) { if (ConstantFP *LHSC = dyn_cast(LHS->getOperand(1))) if (ConstantFP *RHSC = dyn_cast(RHS->getOperand(1))) { // If either of the constants are nans, then the whole thing returns // true. if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) return Builder->getTrue(); // Otherwise, no need to compare the two constants, compare the // rest. return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0)); } // Handle vector zeros. This occurs because the canonical form of // "fcmp uno x,x" is "fcmp uno x, 0". if (isa(LHS->getOperand(1)) && isa(RHS->getOperand(1))) return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0)); return nullptr; } return nullptr; } /// This helper function folds: /// /// ((A | B) & C1) | (B & C2) /// /// into: /// /// (A & C1) | B /// /// when the XOR of the two constants is "all ones" (-1). Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A, Value *B, Value *C) { ConstantInt *CI1 = dyn_cast(C); if (!CI1) return nullptr; Value *V1 = nullptr; ConstantInt *CI2 = nullptr; if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return nullptr; APInt Xor = CI1->getValue() ^ CI2->getValue(); if (!Xor.isAllOnesValue()) return nullptr; if (V1 == A || V1 == B) { Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1); return BinaryOperator::CreateOr(NewOp, V1); } return nullptr; } /// \brief This helper function folds: /// /// ((A | B) & C1) ^ (B & C2) /// /// into: /// /// (A & C1) ^ B /// /// when the XOR of the two constants is "all ones" (-1). Instruction *InstCombiner::FoldXorWithConstants(BinaryOperator &I, Value *Op, Value *A, Value *B, Value *C) { ConstantInt *CI1 = dyn_cast(C); if (!CI1) return nullptr; Value *V1 = nullptr; ConstantInt *CI2 = nullptr; if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return nullptr; APInt Xor = CI1->getValue() ^ CI2->getValue(); if (!Xor.isAllOnesValue()) return nullptr; if (V1 == A || V1 == B) { Value *NewOp = Builder->CreateAnd(V1 == A ? B : A, CI1); return BinaryOperator::CreateXor(NewOp, V1); } return nullptr; } // FIXME: We use commutative matchers (m_c_*) for some, but not all, matches // here. We should standardize that construct where it is needed or choose some // other way to ensure that commutated variants of patterns are not missed. Instruction *InstCombiner::visitOr(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Value *V = SimplifyVectorOp(I)) return replaceInstUsesWith(I, V); if (Value *V = SimplifyOrInst(Op0, Op1, DL, &TLI, &DT, &AC)) return replaceInstUsesWith(I, V); // (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)) return replaceInstUsesWith(I, V); if (ConstantInt *RHS = dyn_cast(Op1)) { ConstantInt *C1 = nullptr; Value *X = nullptr; // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2) if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && Op0->hasOneUse()) { Value *Or = Builder->CreateOr(X, RHS); Or->takeName(Op0); return BinaryOperator::CreateXor(Or, Builder->getInt(C1->getValue() & ~RHS->getValue())); } } if (isa(Op1)) if (Instruction *FoldedLogic = foldOpWithConstantIntoOperand(I)) return FoldedLogic; // Given an OR instruction, check to see if this is a bswap. if (Instruction *BSwap = MatchBSwap(I)) return BSwap; { Value *A; const APInt *C; // (X^C)|Y -> (X|Y)^C iff Y&C == 0 if (match(Op0, m_OneUse(m_Xor(m_Value(A), m_APInt(C)))) && MaskedValueIsZero(Op1, *C, 0, &I)) { Value *NOr = Builder->CreateOr(A, Op1); NOr->takeName(Op0); return BinaryOperator::CreateXor(NOr, ConstantInt::get(NOr->getType(), *C)); } // Y|(X^C) -> (X|Y)^C iff Y&C == 0 if (match(Op1, m_OneUse(m_Xor(m_Value(A), m_APInt(C)))) && MaskedValueIsZero(Op0, *C, 0, &I)) { Value *NOr = Builder->CreateOr(A, Op0); NOr->takeName(Op0); return BinaryOperator::CreateXor(NOr, ConstantInt::get(NOr->getType(), *C)); } } Value *A, *B; // ((~A & B) | A) -> (A | B) if (match(Op0, m_c_And(m_Not(m_Specific(Op1)), m_Value(A)))) return BinaryOperator::CreateOr(A, Op1); if (match(Op1, m_c_And(m_Not(m_Specific(Op0)), m_Value(A)))) return BinaryOperator::CreateOr(Op0, A); // ((A & B) | ~A) -> (~A | B) // The NOT is guaranteed to be in the RHS by complexity ordering. if (match(Op1, m_Not(m_Value(A))) && match(Op0, m_c_And(m_Specific(A), m_Value(B)))) return BinaryOperator::CreateOr(Op1, B); // (A & ~B) | (A ^ B) -> (A ^ B) // (~B & A) | (A ^ B) -> (A ^ B) if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && match(Op1, m_Xor(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); // Commute the 'or' operands. // (A ^ B) | (A & ~B) -> (A ^ B) // (A ^ B) | (~B & A) -> (A ^ B) if (match(Op1, m_c_And(m_Value(A), m_Not(m_Value(B)))) && match(Op0, m_Xor(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); // (A & C)|(B & D) Value *C = nullptr, *D = nullptr; if (match(Op0, m_And(m_Value(A), m_Value(C))) && match(Op1, m_And(m_Value(B), m_Value(D)))) { Value *V1 = nullptr, *V2 = nullptr; ConstantInt *C1 = dyn_cast(C); ConstantInt *C2 = dyn_cast(D); if (C1 && C2) { // (A & C1)|(B & C2) if ((C1->getValue() & C2->getValue()) == 0) { // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2) // iff (C1&C2) == 0 and (N&~C1) == 0 if (match(A, m_Or(m_Value(V1), m_Value(V2))) && ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue(), 0, &I)) || // (V|N) (V2 == B && MaskedValueIsZero(V1, ~C1->getValue(), 0, &I)))) // (N|V) return BinaryOperator::CreateAnd(A, Builder->getInt(C1->getValue()|C2->getValue())); // Or commutes, try both ways. if (match(B, m_Or(m_Value(V1), m_Value(V2))) && ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue(), 0, &I)) || // (V|N) (V2 == A && MaskedValueIsZero(V1, ~C2->getValue(), 0, &I)))) // (N|V) return BinaryOperator::CreateAnd(B, Builder->getInt(C1->getValue()|C2->getValue())); // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2) // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0. ConstantInt *C3 = nullptr, *C4 = nullptr; if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) && (C3->getValue() & ~C1->getValue()) == 0 && match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) && (C4->getValue() & ~C2->getValue()) == 0) { V2 = Builder->CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield"); return BinaryOperator::CreateAnd(V2, Builder->getInt(C1->getValue()|C2->getValue())); } } } // 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, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(A, C, D, B, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(C, A, B, D, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(C, A, D, B, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(B, D, A, C, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(B, D, C, A, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(D, B, A, C, *Builder)) return replaceInstUsesWith(I, V); if (Value *V = matchSelectFromAndOr(D, B, C, A, *Builder)) return replaceInstUsesWith(I, V); } // ((A&~B)|(~A&B)) -> A^B if ((match(C, m_Not(m_Specific(D))) && match(B, m_Not(m_Specific(A))))) return BinaryOperator::CreateXor(A, D); // ((~B&A)|(~A&B)) -> A^B if ((match(A, m_Not(m_Specific(D))) && match(B, m_Not(m_Specific(C))))) return BinaryOperator::CreateXor(C, D); // ((A&~B)|(B&~A)) -> A^B if ((match(C, m_Not(m_Specific(B))) && match(D, m_Not(m_Specific(A))))) return BinaryOperator::CreateXor(A, B); // ((~B&A)|(B&~A)) -> A^B if ((match(A, m_Not(m_Specific(B))) && match(D, m_Not(m_Specific(C))))) return BinaryOperator::CreateXor(C, B); // ((A|B)&1)|(B&-2) -> (A&1) | B if (match(A, m_Or(m_Value(V1), m_Specific(B))) || match(A, m_Or(m_Specific(B), m_Value(V1)))) { Instruction *Ret = FoldOrWithConstants(I, Op1, V1, B, C); if (Ret) return Ret; } // (B&-2)|((A|B)&1) -> (A&1) | B if (match(B, m_Or(m_Specific(A), m_Value(V1))) || match(B, m_Or(m_Value(V1), m_Specific(A)))) { Instruction *Ret = FoldOrWithConstants(I, Op0, A, V1, D); if (Ret) return Ret; } // ((A^B)&1)|(B&-2) -> (A&1) ^ B if (match(A, m_Xor(m_Value(V1), m_Specific(B))) || match(A, m_Xor(m_Specific(B), m_Value(V1)))) { Instruction *Ret = FoldXorWithConstants(I, Op1, V1, B, C); if (Ret) return Ret; } // (B&-2)|((A^B)&1) -> (A&1) ^ B if (match(B, m_Xor(m_Specific(A), m_Value(V1))) || match(B, m_Xor(m_Value(V1), m_Specific(A)))) { Instruction *Ret = FoldXorWithConstants(I, Op0, A, V1, D); if (Ret) return Ret; } } // (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() || cast(Op1)->hasOneUse()) 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)))) if (Op0->hasOneUse() || cast(Op0)->hasOneUse()) return BinaryOperator::CreateOr(Op1, C); // ((B | C) & A) | B -> B | (A & C) if (match(Op0, m_And(m_Or(m_Specific(Op1), m_Value(C)), m_Value(A)))) return BinaryOperator::CreateOr(Op1, Builder->CreateAnd(A, C)); if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder)) return DeMorgan; // Canonicalize xor to the RHS. bool SwappedForXor = false; if (match(Op0, m_Xor(m_Value(), m_Value()))) { std::swap(Op0, Op1); SwappedForXor = true; } // A | ( A ^ B) -> A | B // A | (~A ^ B) -> A | ~B // (A & B) | (A ^ B) if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) { if (Op0 == A || Op0 == B) return BinaryOperator::CreateOr(A, B); if (match(Op0, m_And(m_Specific(A), m_Specific(B))) || match(Op0, m_And(m_Specific(B), m_Specific(A)))) return BinaryOperator::CreateOr(A, B); if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) { Value *Not = Builder->CreateNot(B, B->getName()+".not"); return BinaryOperator::CreateOr(Not, Op0); } if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) { Value *Not = Builder->CreateNot(A, A->getName()+".not"); return BinaryOperator::CreateOr(Not, Op0); } } // A | ~(A | B) -> A | ~B // A | ~(A ^ B) -> A | ~B if (match(Op1, m_Not(m_Value(A)))) if (BinaryOperator *B = dyn_cast(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); } // (A & B) | (~A ^ B) -> (~A ^ B) // (A & B) | (B ^ ~A) -> (~A ^ B) // (B & A) | (~A ^ B) -> (~A ^ B) // (B & A) | (B ^ ~A) -> (~A ^ B) // The match order is important: match the xor first because the 'not' // operation defines 'A'. We do not need to match the xor as Op0 because the // xor was canonicalized to Op1 above. if (match(Op1, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) && match(Op0, m_c_And(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateXor(Builder->CreateNot(A), B); 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)); } } // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y) if (FCmpInst *LHS = dyn_cast(I.getOperand(0))) if (FCmpInst *RHS = dyn_cast(I.getOperand(1))) if (Value *Res = FoldOrOfFCmps(LHS, RHS)) return replaceInstUsesWith(I, Res); if (Instruction *CastedOr = foldCastedBitwiseLogic(I)) return CastedOr; // or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or . if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) && A->getType()->getScalarType()->isIntegerTy(1)) return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1); if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) && A->getType()->getScalarType()->isIntegerTy(1)) return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0); // Note: If we've gotten to the point of visiting the outer OR, then the // inner one couldn't be simplified. If it was a constant, then it won't // be simplified by a later pass either, so we try swapping the inner/outer // ORs in the hopes that we'll be able to simplify it this way. // (X|C) | V --> (X|V) | C ConstantInt *C1; if (Op0->hasOneUse() && !isa(Op1) && match(Op0, m_Or(m_Value(A), m_ConstantInt(C1)))) { Value *Inner = Builder->CreateOr(A, Op1); Inner->takeName(Op0); return BinaryOperator::CreateOr(Inner, C1); } // 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); } } return Changed ? &I : nullptr; } // FIXME: We use commutative matchers (m_c_*) for some, but not all, matches // here. We should standardize that construct where it is needed or choose some // other way to ensure that commutated variants of patterns are not missed. Instruction *InstCombiner::visitXor(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Value *V = SimplifyVectorOp(I)) return replaceInstUsesWith(I, V); if (Value *V = SimplifyXorInst(Op0, Op1, DL, &TLI, &DT, &AC)) return replaceInstUsesWith(I, V); // (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)) return replaceInstUsesWith(I, V); // Is this a ~ operation? if (Value *NotOp = dyn_castNotVal(&I)) { if (BinaryOperator *Op0I = dyn_cast(NotOp)) { if (Op0I->getOpcode() == Instruction::And || Op0I->getOpcode() == Instruction::Or) { // ~(~X & Y) --> (X | ~Y) - De Morgan's Law // ~(~X | Y) === (X & ~Y) - De Morgan's Law if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands(); if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) { Value *NotY = Builder->CreateNot(Op0I->getOperand(1), Op0I->getOperand(1)->getName()+".not"); if (Op0I->getOpcode() == Instruction::And) return BinaryOperator::CreateOr(Op0NotVal, NotY); return BinaryOperator::CreateAnd(Op0NotVal, NotY); } // ~(X & Y) --> (~X | ~Y) - De Morgan's Law // ~(X | Y) === (~X & ~Y) - De Morgan's Law if (IsFreeToInvert(Op0I->getOperand(0), Op0I->getOperand(0)->hasOneUse()) && IsFreeToInvert(Op0I->getOperand(1), Op0I->getOperand(1)->hasOneUse())) { Value *NotX = Builder->CreateNot(Op0I->getOperand(0), "notlhs"); Value *NotY = Builder->CreateNot(Op0I->getOperand(1), "notrhs"); if (Op0I->getOpcode() == Instruction::And) return BinaryOperator::CreateOr(NotX, NotY); return BinaryOperator::CreateAnd(NotX, NotY); } } else if (Op0I->getOpcode() == Instruction::AShr) { // ~(~X >>s Y) --> (X >>s Y) if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1)); } } } // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B ICmpInst::Predicate Pred; if (match(Op0, m_OneUse(m_Cmp(Pred, m_Value(), m_Value()))) && match(Op1, m_AllOnes())) { cast(Op0)->setPredicate(CmpInst::getInversePredicate(Pred)); return replaceInstUsesWith(I, Op0); } if (ConstantInt *RHSC = dyn_cast(Op1)) { // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp). if (CastInst *Op0C = dyn_cast(Op0)) { if (CmpInst *CI = dyn_cast(Op0C->getOperand(0))) { if (CI->hasOneUse() && Op0C->hasOneUse()) { Instruction::CastOps Opcode = Op0C->getOpcode(); if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) && (RHSC == ConstantExpr::getCast(Opcode, Builder->getTrue(), Op0C->getDestTy()))) { CI->setPredicate(CI->getInversePredicate()); return CastInst::Create(Opcode, CI, Op0C->getType()); } } } } if (BinaryOperator *Op0I = dyn_cast(Op0)) { // ~(c-X) == X-c-1 == X+(-c-1) if (Op0I->getOpcode() == Instruction::Sub && RHSC->isAllOnesValue()) if (Constant *Op0I0C = dyn_cast(Op0I->getOperand(0))) { Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C); return BinaryOperator::CreateAdd(Op0I->getOperand(1), SubOne(NegOp0I0C)); } if (ConstantInt *Op0CI = dyn_cast(Op0I->getOperand(1))) { if (Op0I->getOpcode() == Instruction::Add) { // ~(X-c) --> (-c-1)-X if (RHSC->isAllOnesValue()) { Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI); return BinaryOperator::CreateSub(SubOne(NegOp0CI), Op0I->getOperand(0)); } else if (RHSC->getValue().isSignMask()) { // (X + C) ^ signmask -> (X + C + signmask) Constant *C = Builder->getInt(RHSC->getValue() + Op0CI->getValue()); return BinaryOperator::CreateAdd(Op0I->getOperand(0), C); } } else if (Op0I->getOpcode() == Instruction::Or) { // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue(), 0, &I)) { Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHSC); // Anything in both C1 and C2 is known to be zero, remove it from // NewRHS. Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHSC); NewRHS = ConstantExpr::getAnd(NewRHS, ConstantExpr::getNot(CommonBits)); Worklist.Add(Op0I); I.setOperand(0, Op0I->getOperand(0)); I.setOperand(1, NewRHS); return &I; } } else if (Op0I->getOpcode() == Instruction::LShr) { // ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3) // E1 = "X ^ C1" BinaryOperator *E1; ConstantInt *C1; if (Op0I->hasOneUse() && (E1 = dyn_cast(Op0I->getOperand(0))) && E1->getOpcode() == Instruction::Xor && (C1 = dyn_cast(E1->getOperand(1)))) { // fold (C1 >> C2) ^ C3 ConstantInt *C2 = Op0CI, *C3 = RHSC; APInt FoldConst = C1->getValue().lshr(C2->getValue()); FoldConst ^= C3->getValue(); // Prepare the two operands. Value *Opnd0 = Builder->CreateLShr(E1->getOperand(0), C2); Opnd0->takeName(Op0I); cast(Opnd0)->setDebugLoc(I.getDebugLoc()); Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst); return BinaryOperator::CreateXor(Opnd0, FoldVal); } } } } } if (isa(Op1)) if (Instruction *FoldedLogic = foldOpWithConstantIntoOperand(I)) return FoldedLogic; { Value *A, *B; if (match(Op1, m_OneUse(m_Or(m_Value(A), m_Value(B))))) { if (A == Op0) { // A^(A|B) == A^(B|A) cast(Op1)->swapOperands(); std::swap(A, B); } if (B == Op0) { // A^(B|A) == (B|A)^A I.swapOperands(); // Simplified below. std::swap(Op0, Op1); } } else if (match(Op1, m_OneUse(m_And(m_Value(A), m_Value(B))))) { if (A == Op0) { // A^(A&B) -> A^(B&A) cast(Op1)->swapOperands(); std::swap(A, B); } if (B == Op0) { // A^(B&A) -> (B&A)^A I.swapOperands(); // Simplified below. std::swap(Op0, Op1); } } } { Value *A, *B; if (match(Op0, m_OneUse(m_Or(m_Value(A), m_Value(B))))) { if (A == Op1) // (B|A)^B == (A|B)^B std::swap(A, B); if (B == Op1) // (A|B)^B == A & ~B return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1)); } else if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B))))) { if (A == Op1) // (A&B)^A -> (B&A)^A std::swap(A, B); const APInt *C; if (B == Op1 && // (B&A)^A == ~B & A !match(Op1, m_APInt(C))) { // Canonical form is (B&C)^C return BinaryOperator::CreateAnd(Builder->CreateNot(A), Op1); } } } { Value *A, *B, *C, *D; // (A & B)^(A | B) -> A ^ B if (match(Op0, m_And(m_Value(A), m_Value(B))) && match(Op1, m_Or(m_Value(C), m_Value(D)))) { if ((A == C && B == D) || (A == D && B == C)) return BinaryOperator::CreateXor(A, B); } // (A | B)^(A & B) -> A ^ B if (match(Op0, m_Or(m_Value(A), m_Value(B))) && match(Op1, m_And(m_Value(C), m_Value(D)))) { if ((A == C && B == D) || (A == D && B == C)) return BinaryOperator::CreateXor(A, B); } // (A | ~B) ^ (~A | B) -> A ^ B // (~B | A) ^ (~A | B) -> A ^ B if (match(Op0, m_c_Or(m_Value(A), m_Not(m_Value(B)))) && match(Op1, m_Or(m_Not(m_Specific(A)), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); // (~A | B) ^ (A | ~B) -> A ^ B if (match(Op0, m_Or(m_Not(m_Value(A)), m_Value(B))) && match(Op1, m_Or(m_Specific(A), m_Not(m_Specific(B))))) { return BinaryOperator::CreateXor(A, B); } // (A & ~B) ^ (~A & B) -> A ^ B // (~B & A) ^ (~A & B) -> A ^ B if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && match(Op1, m_And(m_Not(m_Specific(A)), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); // (~A & B) ^ (A & ~B) -> A ^ B if (match(Op0, m_And(m_Not(m_Value(A)), m_Value(B))) && match(Op1, m_And(m_Specific(A), m_Not(m_Specific(B))))) { return BinaryOperator::CreateXor(A, B); } // (A ^ C)^(A | B) -> ((~A) & B) ^ C if (match(Op0, m_Xor(m_Value(D), m_Value(C))) && match(Op1, m_Or(m_Value(A), m_Value(B)))) { if (D == A) return BinaryOperator::CreateXor( Builder->CreateAnd(Builder->CreateNot(A), B), C); if (D == B) return BinaryOperator::CreateXor( Builder->CreateAnd(Builder->CreateNot(B), A), C); } // (A | B)^(A ^ C) -> ((~A) & B) ^ C if (match(Op0, m_Or(m_Value(A), m_Value(B))) && match(Op1, m_Xor(m_Value(D), m_Value(C)))) { if (D == A) return BinaryOperator::CreateXor( Builder->CreateAnd(Builder->CreateNot(A), B), C); if (D == B) return BinaryOperator::CreateXor( Builder->CreateAnd(Builder->CreateNot(B), A), C); } // (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) Value *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)); // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B) if (ICmpInst *RHS = dyn_cast(I.getOperand(1))) if (ICmpInst *LHS = dyn_cast(I.getOperand(0))) 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)) { Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1); unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS); bool isSigned = LHS->isSigned() || RHS->isSigned(); return replaceInstUsesWith(I, getNewICmpValue(isSigned, Code, Op0, Op1, Builder)); } } if (Instruction *CastedXor = foldCastedBitwiseLogic(I)) return CastedXor; return Changed ? &I : nullptr; }