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Diffstat (limited to 'contrib/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 1984 |
1 files changed, 0 insertions, 1984 deletions
diff --git a/contrib/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/contrib/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp deleted file mode 100644 index ba15b023f2a3..000000000000 --- a/contrib/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ /dev/null @@ -1,1984 +0,0 @@ -//===- InstCombineAddSub.cpp ------------------------------------*- C++ -*-===// -// -// 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 visit functions for add, fadd, sub, and fsub. -// -//===----------------------------------------------------------------------===// - -#include "InstCombineInternal.h" -#include "llvm/ADT/APFloat.h" -#include "llvm/ADT/APInt.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/Analysis/InstructionSimplify.h" -#include "llvm/Analysis/ValueTracking.h" -#include "llvm/IR/Constant.h" -#include "llvm/IR/Constants.h" -#include "llvm/IR/InstrTypes.h" -#include "llvm/IR/Instruction.h" -#include "llvm/IR/Instructions.h" -#include "llvm/IR/Operator.h" -#include "llvm/IR/PatternMatch.h" -#include "llvm/IR/Type.h" -#include "llvm/IR/Value.h" -#include "llvm/Support/AlignOf.h" -#include "llvm/Support/Casting.h" -#include "llvm/Support/KnownBits.h" -#include <cassert> -#include <utility> - -using namespace llvm; -using namespace PatternMatch; - -#define DEBUG_TYPE "instcombine" - -namespace { - - /// Class representing coefficient of floating-point addend. - /// This class needs to be highly efficient, which is especially true for - /// the constructor. As of I write this comment, the cost of the default - /// constructor is merely 4-byte-store-zero (Assuming compiler is able to - /// perform write-merging). - /// - class FAddendCoef { - public: - // The constructor has to initialize a APFloat, which is unnecessary for - // most addends which have coefficient either 1 or -1. So, the constructor - // is expensive. In order to avoid the cost of the constructor, we should - // reuse some instances whenever possible. The pre-created instances - // FAddCombine::Add[0-5] embodies this idea. - FAddendCoef() = default; - ~FAddendCoef(); - - // If possible, don't define operator+/operator- etc because these - // operators inevitably call FAddendCoef's constructor which is not cheap. - void operator=(const FAddendCoef &A); - void operator+=(const FAddendCoef &A); - void operator*=(const FAddendCoef &S); - - void set(short C) { - assert(!insaneIntVal(C) && "Insane coefficient"); - IsFp = false; IntVal = C; - } - - void set(const APFloat& C); - - void negate(); - - bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); } - Value *getValue(Type *) const; - - bool isOne() const { return isInt() && IntVal == 1; } - bool isTwo() const { return isInt() && IntVal == 2; } - bool isMinusOne() const { return isInt() && IntVal == -1; } - bool isMinusTwo() const { return isInt() && IntVal == -2; } - - private: - bool insaneIntVal(int V) { return V > 4 || V < -4; } - - APFloat *getFpValPtr() - { return reinterpret_cast<APFloat *>(&FpValBuf.buffer[0]); } - - const APFloat *getFpValPtr() const - { return reinterpret_cast<const APFloat *>(&FpValBuf.buffer[0]); } - - const APFloat &getFpVal() const { - assert(IsFp && BufHasFpVal && "Incorret state"); - return *getFpValPtr(); - } - - APFloat &getFpVal() { - assert(IsFp && BufHasFpVal && "Incorret state"); - return *getFpValPtr(); - } - - bool isInt() const { return !IsFp; } - - // If the coefficient is represented by an integer, promote it to a - // floating point. - void convertToFpType(const fltSemantics &Sem); - - // Construct an APFloat from a signed integer. - // TODO: We should get rid of this function when APFloat can be constructed - // from an *SIGNED* integer. - APFloat createAPFloatFromInt(const fltSemantics &Sem, int Val); - - bool IsFp = false; - - // True iff FpValBuf contains an instance of APFloat. - bool BufHasFpVal = false; - - // The integer coefficient of an individual addend is either 1 or -1, - // and we try to simplify at most 4 addends from neighboring at most - // two instructions. So the range of <IntVal> falls in [-4, 4]. APInt - // is overkill of this end. - short IntVal = 0; - - AlignedCharArrayUnion<APFloat> FpValBuf; - }; - - /// FAddend is used to represent floating-point addend. An addend is - /// represented as <C, V>, where the V is a symbolic value, and C is a - /// constant coefficient. A constant addend is represented as <C, 0>. - class FAddend { - public: - FAddend() = default; - - void operator+=(const FAddend &T) { - assert((Val == T.Val) && "Symbolic-values disagree"); - Coeff += T.Coeff; - } - - Value *getSymVal() const { return Val; } - const FAddendCoef &getCoef() const { return Coeff; } - - bool isConstant() const { return Val == nullptr; } - bool isZero() const { return Coeff.isZero(); } - - void set(short Coefficient, Value *V) { - Coeff.set(Coefficient); - Val = V; - } - void set(const APFloat &Coefficient, Value *V) { - Coeff.set(Coefficient); - Val = V; - } - void set(const ConstantFP *Coefficient, Value *V) { - Coeff.set(Coefficient->getValueAPF()); - Val = V; - } - - void negate() { Coeff.negate(); } - - /// Drill down the U-D chain one step to find the definition of V, and - /// try to break the definition into one or two addends. - static unsigned drillValueDownOneStep(Value* V, FAddend &A0, FAddend &A1); - - /// Similar to FAddend::drillDownOneStep() except that the value being - /// splitted is the addend itself. - unsigned drillAddendDownOneStep(FAddend &Addend0, FAddend &Addend1) const; - - private: - void Scale(const FAddendCoef& ScaleAmt) { Coeff *= ScaleAmt; } - - // This addend has the value of "Coeff * Val". - Value *Val = nullptr; - FAddendCoef Coeff; - }; - - /// FAddCombine is the class for optimizing an unsafe fadd/fsub along - /// with its neighboring at most two instructions. - /// - class FAddCombine { - public: - FAddCombine(InstCombiner::BuilderTy &B) : Builder(B) {} - - Value *simplify(Instruction *FAdd); - - private: - using AddendVect = SmallVector<const FAddend *, 4>; - - Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota); - - /// Convert given addend to a Value - Value *createAddendVal(const FAddend &A, bool& NeedNeg); - - /// Return the number of instructions needed to emit the N-ary addition. - unsigned calcInstrNumber(const AddendVect& Vect); - - Value *createFSub(Value *Opnd0, Value *Opnd1); - Value *createFAdd(Value *Opnd0, Value *Opnd1); - Value *createFMul(Value *Opnd0, Value *Opnd1); - Value *createFNeg(Value *V); - Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota); - void createInstPostProc(Instruction *NewInst, bool NoNumber = false); - - // Debugging stuff are clustered here. - #ifndef NDEBUG - unsigned CreateInstrNum; - void initCreateInstNum() { CreateInstrNum = 0; } - void incCreateInstNum() { CreateInstrNum++; } - #else - void initCreateInstNum() {} - void incCreateInstNum() {} - #endif - - InstCombiner::BuilderTy &Builder; - Instruction *Instr = nullptr; - }; - -} // end anonymous namespace - -//===----------------------------------------------------------------------===// -// -// Implementation of -// {FAddendCoef, FAddend, FAddition, FAddCombine}. -// -//===----------------------------------------------------------------------===// -FAddendCoef::~FAddendCoef() { - if (BufHasFpVal) - getFpValPtr()->~APFloat(); -} - -void FAddendCoef::set(const APFloat& C) { - APFloat *P = getFpValPtr(); - - if (isInt()) { - // As the buffer is meanless byte stream, we cannot call - // APFloat::operator=(). - new(P) APFloat(C); - } else - *P = C; - - IsFp = BufHasFpVal = true; -} - -void FAddendCoef::convertToFpType(const fltSemantics &Sem) { - if (!isInt()) - return; - - APFloat *P = getFpValPtr(); - if (IntVal > 0) - new(P) APFloat(Sem, IntVal); - else { - new(P) APFloat(Sem, 0 - IntVal); - P->changeSign(); - } - IsFp = BufHasFpVal = true; -} - -APFloat FAddendCoef::createAPFloatFromInt(const fltSemantics &Sem, int Val) { - if (Val >= 0) - return APFloat(Sem, Val); - - APFloat T(Sem, 0 - Val); - T.changeSign(); - - return T; -} - -void FAddendCoef::operator=(const FAddendCoef &That) { - if (That.isInt()) - set(That.IntVal); - else - set(That.getFpVal()); -} - -void FAddendCoef::operator+=(const FAddendCoef &That) { - enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven; - if (isInt() == That.isInt()) { - if (isInt()) - IntVal += That.IntVal; - else - getFpVal().add(That.getFpVal(), RndMode); - return; - } - - if (isInt()) { - const APFloat &T = That.getFpVal(); - convertToFpType(T.getSemantics()); - getFpVal().add(T, RndMode); - return; - } - - APFloat &T = getFpVal(); - T.add(createAPFloatFromInt(T.getSemantics(), That.IntVal), RndMode); -} - -void FAddendCoef::operator*=(const FAddendCoef &That) { - if (That.isOne()) - return; - - if (That.isMinusOne()) { - negate(); - return; - } - - if (isInt() && That.isInt()) { - int Res = IntVal * (int)That.IntVal; - assert(!insaneIntVal(Res) && "Insane int value"); - IntVal = Res; - return; - } - - const fltSemantics &Semantic = - isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics(); - - if (isInt()) - convertToFpType(Semantic); - APFloat &F0 = getFpVal(); - - if (That.isInt()) - F0.multiply(createAPFloatFromInt(Semantic, That.IntVal), - APFloat::rmNearestTiesToEven); - else - F0.multiply(That.getFpVal(), APFloat::rmNearestTiesToEven); -} - -void FAddendCoef::negate() { - if (isInt()) - IntVal = 0 - IntVal; - else - getFpVal().changeSign(); -} - -Value *FAddendCoef::getValue(Type *Ty) const { - return isInt() ? - ConstantFP::get(Ty, float(IntVal)) : - ConstantFP::get(Ty->getContext(), getFpVal()); -} - -// The definition of <Val> Addends -// ========================================= -// A + B <1, A>, <1,B> -// A - B <1, A>, <1,B> -// 0 - B <-1, B> -// C * A, <C, A> -// A + C <1, A> <C, NULL> -// 0 +/- 0 <0, NULL> (corner case) -// -// Legend: A and B are not constant, C is constant -unsigned FAddend::drillValueDownOneStep - (Value *Val, FAddend &Addend0, FAddend &Addend1) { - Instruction *I = nullptr; - if (!Val || !(I = dyn_cast<Instruction>(Val))) - return 0; - - unsigned Opcode = I->getOpcode(); - - if (Opcode == Instruction::FAdd || Opcode == Instruction::FSub) { - ConstantFP *C0, *C1; - Value *Opnd0 = I->getOperand(0); - Value *Opnd1 = I->getOperand(1); - if ((C0 = dyn_cast<ConstantFP>(Opnd0)) && C0->isZero()) - Opnd0 = nullptr; - - if ((C1 = dyn_cast<ConstantFP>(Opnd1)) && C1->isZero()) - Opnd1 = nullptr; - - if (Opnd0) { - if (!C0) - Addend0.set(1, Opnd0); - else - Addend0.set(C0, nullptr); - } - - if (Opnd1) { - FAddend &Addend = Opnd0 ? Addend1 : Addend0; - if (!C1) - Addend.set(1, Opnd1); - else - Addend.set(C1, nullptr); - if (Opcode == Instruction::FSub) - Addend.negate(); - } - - if (Opnd0 || Opnd1) - return Opnd0 && Opnd1 ? 2 : 1; - - // Both operands are zero. Weird! - Addend0.set(APFloat(C0->getValueAPF().getSemantics()), nullptr); - return 1; - } - - if (I->getOpcode() == Instruction::FMul) { - Value *V0 = I->getOperand(0); - Value *V1 = I->getOperand(1); - if (ConstantFP *C = dyn_cast<ConstantFP>(V0)) { - Addend0.set(C, V1); - return 1; - } - - if (ConstantFP *C = dyn_cast<ConstantFP>(V1)) { - Addend0.set(C, V0); - return 1; - } - } - - return 0; -} - -// Try to break *this* addend into two addends. e.g. Suppose this addend is -// <2.3, V>, and V = X + Y, by calling this function, we obtain two addends, -// i.e. <2.3, X> and <2.3, Y>. -unsigned FAddend::drillAddendDownOneStep - (FAddend &Addend0, FAddend &Addend1) const { - if (isConstant()) - return 0; - - unsigned BreakNum = FAddend::drillValueDownOneStep(Val, Addend0, Addend1); - if (!BreakNum || Coeff.isOne()) - return BreakNum; - - Addend0.Scale(Coeff); - - if (BreakNum == 2) - Addend1.Scale(Coeff); - - return BreakNum; -} - -Value *FAddCombine::simplify(Instruction *I) { - assert(I->hasAllowReassoc() && I->hasNoSignedZeros() && - "Expected 'reassoc'+'nsz' instruction"); - - // Currently we are not able to handle vector type. - if (I->getType()->isVectorTy()) - return nullptr; - - assert((I->getOpcode() == Instruction::FAdd || - I->getOpcode() == Instruction::FSub) && "Expect add/sub"); - - // Save the instruction before calling other member-functions. - Instr = I; - - FAddend Opnd0, Opnd1, Opnd0_0, Opnd0_1, Opnd1_0, Opnd1_1; - - unsigned OpndNum = FAddend::drillValueDownOneStep(I, Opnd0, Opnd1); - - // Step 1: Expand the 1st addend into Opnd0_0 and Opnd0_1. - unsigned Opnd0_ExpNum = 0; - unsigned Opnd1_ExpNum = 0; - - if (!Opnd0.isConstant()) - Opnd0_ExpNum = Opnd0.drillAddendDownOneStep(Opnd0_0, Opnd0_1); - - // Step 2: Expand the 2nd addend into Opnd1_0 and Opnd1_1. - if (OpndNum == 2 && !Opnd1.isConstant()) - Opnd1_ExpNum = Opnd1.drillAddendDownOneStep(Opnd1_0, Opnd1_1); - - // Step 3: Try to optimize Opnd0_0 + Opnd0_1 + Opnd1_0 + Opnd1_1 - if (Opnd0_ExpNum && Opnd1_ExpNum) { - AddendVect AllOpnds; - AllOpnds.push_back(&Opnd0_0); - AllOpnds.push_back(&Opnd1_0); - if (Opnd0_ExpNum == 2) - AllOpnds.push_back(&Opnd0_1); - if (Opnd1_ExpNum == 2) - AllOpnds.push_back(&Opnd1_1); - - // Compute instruction quota. We should save at least one instruction. - unsigned InstQuota = 0; - - Value *V0 = I->getOperand(0); - Value *V1 = I->getOperand(1); - InstQuota = ((!isa<Constant>(V0) && V0->hasOneUse()) && - (!isa<Constant>(V1) && V1->hasOneUse())) ? 2 : 1; - - if (Value *R = simplifyFAdd(AllOpnds, InstQuota)) - return R; - } - - if (OpndNum != 2) { - // The input instruction is : "I=0.0 +/- V". If the "V" were able to be - // splitted into two addends, say "V = X - Y", the instruction would have - // been optimized into "I = Y - X" in the previous steps. - // - const FAddendCoef &CE = Opnd0.getCoef(); - return CE.isOne() ? Opnd0.getSymVal() : nullptr; - } - - // step 4: Try to optimize Opnd0 + Opnd1_0 [+ Opnd1_1] - if (Opnd1_ExpNum) { - AddendVect AllOpnds; - AllOpnds.push_back(&Opnd0); - AllOpnds.push_back(&Opnd1_0); - if (Opnd1_ExpNum == 2) - AllOpnds.push_back(&Opnd1_1); - - if (Value *R = simplifyFAdd(AllOpnds, 1)) - return R; - } - - // step 5: Try to optimize Opnd1 + Opnd0_0 [+ Opnd0_1] - if (Opnd0_ExpNum) { - AddendVect AllOpnds; - AllOpnds.push_back(&Opnd1); - AllOpnds.push_back(&Opnd0_0); - if (Opnd0_ExpNum == 2) - AllOpnds.push_back(&Opnd0_1); - - if (Value *R = simplifyFAdd(AllOpnds, 1)) - return R; - } - - return nullptr; -} - -Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) { - unsigned AddendNum = Addends.size(); - assert(AddendNum <= 4 && "Too many addends"); - - // For saving intermediate results; - unsigned NextTmpIdx = 0; - FAddend TmpResult[3]; - - // Points to the constant addend of the resulting simplified expression. - // If the resulting expr has constant-addend, this constant-addend is - // desirable to reside at the top of the resulting expression tree. Placing - // constant close to supper-expr(s) will potentially reveal some optimization - // opportunities in super-expr(s). - const FAddend *ConstAdd = nullptr; - - // Simplified addends are placed <SimpVect>. - AddendVect SimpVect; - - // The outer loop works on one symbolic-value at a time. Suppose the input - // addends are : <a1, x>, <b1, y>, <a2, x>, <c1, z>, <b2, y>, ... - // The symbolic-values will be processed in this order: x, y, z. - for (unsigned SymIdx = 0; SymIdx < AddendNum; SymIdx++) { - - const FAddend *ThisAddend = Addends[SymIdx]; - if (!ThisAddend) { - // This addend was processed before. - continue; - } - - Value *Val = ThisAddend->getSymVal(); - unsigned StartIdx = SimpVect.size(); - SimpVect.push_back(ThisAddend); - - // The inner loop collects addends sharing same symbolic-value, and these - // addends will be later on folded into a single addend. Following above - // example, if the symbolic value "y" is being processed, the inner loop - // will collect two addends "<b1,y>" and "<b2,Y>". These two addends will - // be later on folded into "<b1+b2, y>". - for (unsigned SameSymIdx = SymIdx + 1; - SameSymIdx < AddendNum; SameSymIdx++) { - const FAddend *T = Addends[SameSymIdx]; - if (T && T->getSymVal() == Val) { - // Set null such that next iteration of the outer loop will not process - // this addend again. - Addends[SameSymIdx] = nullptr; - SimpVect.push_back(T); - } - } - - // If multiple addends share same symbolic value, fold them together. - if (StartIdx + 1 != SimpVect.size()) { - FAddend &R = TmpResult[NextTmpIdx ++]; - R = *SimpVect[StartIdx]; - for (unsigned Idx = StartIdx + 1; Idx < SimpVect.size(); Idx++) - R += *SimpVect[Idx]; - - // Pop all addends being folded and push the resulting folded addend. - SimpVect.resize(StartIdx); - if (Val) { - if (!R.isZero()) { - SimpVect.push_back(&R); - } - } else { - // Don't push constant addend at this time. It will be the last element - // of <SimpVect>. - ConstAdd = &R; - } - } - } - - assert((NextTmpIdx <= array_lengthof(TmpResult) + 1) && - "out-of-bound access"); - - if (ConstAdd) - SimpVect.push_back(ConstAdd); - - Value *Result; - if (!SimpVect.empty()) - Result = createNaryFAdd(SimpVect, InstrQuota); - else { - // The addition is folded to 0.0. - Result = ConstantFP::get(Instr->getType(), 0.0); - } - - return Result; -} - -Value *FAddCombine::createNaryFAdd - (const AddendVect &Opnds, unsigned InstrQuota) { - assert(!Opnds.empty() && "Expect at least one addend"); - - // Step 1: Check if the # of instructions needed exceeds the quota. - - unsigned InstrNeeded = calcInstrNumber(Opnds); - if (InstrNeeded > InstrQuota) - return nullptr; - - initCreateInstNum(); - - // step 2: Emit the N-ary addition. - // Note that at most three instructions are involved in Fadd-InstCombine: the - // addition in question, and at most two neighboring instructions. - // The resulting optimized addition should have at least one less instruction - // than the original addition expression tree. This implies that the resulting - // N-ary addition has at most two instructions, and we don't need to worry - // about tree-height when constructing the N-ary addition. - - Value *LastVal = nullptr; - bool LastValNeedNeg = false; - - // Iterate the addends, creating fadd/fsub using adjacent two addends. - for (const FAddend *Opnd : Opnds) { - bool NeedNeg; - Value *V = createAddendVal(*Opnd, NeedNeg); - if (!LastVal) { - LastVal = V; - LastValNeedNeg = NeedNeg; - continue; - } - - if (LastValNeedNeg == NeedNeg) { - LastVal = createFAdd(LastVal, V); - continue; - } - - if (LastValNeedNeg) - LastVal = createFSub(V, LastVal); - else - LastVal = createFSub(LastVal, V); - - LastValNeedNeg = false; - } - - if (LastValNeedNeg) { - LastVal = createFNeg(LastVal); - } - -#ifndef NDEBUG - assert(CreateInstrNum == InstrNeeded && - "Inconsistent in instruction numbers"); -#endif - - return LastVal; -} - -Value *FAddCombine::createFSub(Value *Opnd0, Value *Opnd1) { - Value *V = Builder.CreateFSub(Opnd0, Opnd1); - if (Instruction *I = dyn_cast<Instruction>(V)) - createInstPostProc(I); - return V; -} - -Value *FAddCombine::createFNeg(Value *V) { - Value *Zero = cast<Value>(ConstantFP::getZeroValueForNegation(V->getType())); - Value *NewV = createFSub(Zero, V); - if (Instruction *I = dyn_cast<Instruction>(NewV)) - createInstPostProc(I, true); // fneg's don't receive instruction numbers. - return NewV; -} - -Value *FAddCombine::createFAdd(Value *Opnd0, Value *Opnd1) { - Value *V = Builder.CreateFAdd(Opnd0, Opnd1); - if (Instruction *I = dyn_cast<Instruction>(V)) - createInstPostProc(I); - return V; -} - -Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) { - Value *V = Builder.CreateFMul(Opnd0, Opnd1); - if (Instruction *I = dyn_cast<Instruction>(V)) - createInstPostProc(I); - return V; -} - -void FAddCombine::createInstPostProc(Instruction *NewInstr, bool NoNumber) { - NewInstr->setDebugLoc(Instr->getDebugLoc()); - - // Keep track of the number of instruction created. - if (!NoNumber) - incCreateInstNum(); - - // Propagate fast-math flags - NewInstr->setFastMathFlags(Instr->getFastMathFlags()); -} - -// Return the number of instruction needed to emit the N-ary addition. -// NOTE: Keep this function in sync with createAddendVal(). -unsigned FAddCombine::calcInstrNumber(const AddendVect &Opnds) { - unsigned OpndNum = Opnds.size(); - unsigned InstrNeeded = OpndNum - 1; - - // The number of addends in the form of "(-1)*x". - unsigned NegOpndNum = 0; - - // Adjust the number of instructions needed to emit the N-ary add. - for (const FAddend *Opnd : Opnds) { - if (Opnd->isConstant()) - continue; - - // The constant check above is really for a few special constant - // coefficients. - if (isa<UndefValue>(Opnd->getSymVal())) - continue; - - const FAddendCoef &CE = Opnd->getCoef(); - if (CE.isMinusOne() || CE.isMinusTwo()) - NegOpndNum++; - - // Let the addend be "c * x". If "c == +/-1", the value of the addend - // is immediately available; otherwise, it needs exactly one instruction - // to evaluate the value. - if (!CE.isMinusOne() && !CE.isOne()) - InstrNeeded++; - } - if (NegOpndNum == OpndNum) - InstrNeeded++; - return InstrNeeded; -} - -// Input Addend Value NeedNeg(output) -// ================================================================ -// Constant C C false -// <+/-1, V> V coefficient is -1 -// <2/-2, V> "fadd V, V" coefficient is -2 -// <C, V> "fmul V, C" false -// -// NOTE: Keep this function in sync with FAddCombine::calcInstrNumber. -Value *FAddCombine::createAddendVal(const FAddend &Opnd, bool &NeedNeg) { - const FAddendCoef &Coeff = Opnd.getCoef(); - - if (Opnd.isConstant()) { - NeedNeg = false; - return Coeff.getValue(Instr->getType()); - } - - Value *OpndVal = Opnd.getSymVal(); - - if (Coeff.isMinusOne() || Coeff.isOne()) { - NeedNeg = Coeff.isMinusOne(); - return OpndVal; - } - - if (Coeff.isTwo() || Coeff.isMinusTwo()) { - NeedNeg = Coeff.isMinusTwo(); - return createFAdd(OpndVal, OpndVal); - } - - NeedNeg = false; - return createFMul(OpndVal, Coeff.getValue(Instr->getType())); -} - -// Checks if any operand is negative and we can convert add to sub. -// This function checks for following negative patterns -// ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C)) -// ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C)) -// XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even -static Value *checkForNegativeOperand(BinaryOperator &I, - InstCombiner::BuilderTy &Builder) { - Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); - - // This function creates 2 instructions to replace ADD, we need at least one - // of LHS or RHS to have one use to ensure benefit in transform. - if (!LHS->hasOneUse() && !RHS->hasOneUse()) - return nullptr; - - Value *X = nullptr, *Y = nullptr, *Z = nullptr; - const APInt *C1 = nullptr, *C2 = nullptr; - - // if ONE is on other side, swap - if (match(RHS, m_Add(m_Value(X), m_One()))) - std::swap(LHS, RHS); - - if (match(LHS, m_Add(m_Value(X), m_One()))) { - // if XOR on other side, swap - if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1)))) - std::swap(X, RHS); - - if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) { - // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1)) - // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1)) - if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) { - Value *NewAnd = Builder.CreateAnd(Z, *C1); - return Builder.CreateSub(RHS, NewAnd, "sub"); - } else if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && (*C1 == *C2)) { - // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1)) - // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1)) - Value *NewOr = Builder.CreateOr(Z, ~(*C1)); - return Builder.CreateSub(RHS, NewOr, "sub"); - } - } - } - - // Restore LHS and RHS - LHS = I.getOperand(0); - RHS = I.getOperand(1); - - // if XOR is on other side, swap - if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1)))) - std::swap(LHS, RHS); - - // C2 is ODD - // LHS = XOR(Y, C1), Y = AND(Z, C2), C1 == (C2 + 1) => LHS == NEG(OR(Z, ~C2)) - // ADD(LHS, RHS) == SUB(RHS, OR(Z, ~C2)) - if (match(LHS, m_Xor(m_Value(Y), m_APInt(C1)))) - if (C1->countTrailingZeros() == 0) - if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && *C1 == (*C2 + 1)) { - Value *NewOr = Builder.CreateOr(Z, ~(*C2)); - return Builder.CreateSub(RHS, NewOr, "sub"); - } - return nullptr; -} - -/// Wrapping flags may allow combining constants separated by an extend. -static Instruction *foldNoWrapAdd(BinaryOperator &Add, - InstCombiner::BuilderTy &Builder) { - Value *Op0 = Add.getOperand(0), *Op1 = Add.getOperand(1); - Type *Ty = Add.getType(); - Constant *Op1C; - if (!match(Op1, m_Constant(Op1C))) - return nullptr; - - // Try this match first because it results in an add in the narrow type. - // (zext (X +nuw C2)) + C1 --> zext (X + (C2 + trunc(C1))) - Value *X; - const APInt *C1, *C2; - if (match(Op1, m_APInt(C1)) && - match(Op0, m_OneUse(m_ZExt(m_NUWAdd(m_Value(X), m_APInt(C2))))) && - C1->isNegative() && C1->sge(-C2->sext(C1->getBitWidth()))) { - Constant *NewC = - ConstantInt::get(X->getType(), *C2 + C1->trunc(C2->getBitWidth())); - return new ZExtInst(Builder.CreateNUWAdd(X, NewC), Ty); - } - - // More general combining of constants in the wide type. - // (sext (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C) - Constant *NarrowC; - if (match(Op0, m_OneUse(m_SExt(m_NSWAdd(m_Value(X), m_Constant(NarrowC)))))) { - Constant *WideC = ConstantExpr::getSExt(NarrowC, Ty); - Constant *NewC = ConstantExpr::getAdd(WideC, Op1C); - Value *WideX = Builder.CreateSExt(X, Ty); - return BinaryOperator::CreateAdd(WideX, NewC); - } - // (zext (X +nuw NarrowC)) + C --> (zext X) + (zext(NarrowC) + C) - if (match(Op0, m_OneUse(m_ZExt(m_NUWAdd(m_Value(X), m_Constant(NarrowC)))))) { - Constant *WideC = ConstantExpr::getZExt(NarrowC, Ty); - Constant *NewC = ConstantExpr::getAdd(WideC, Op1C); - Value *WideX = Builder.CreateZExt(X, Ty); - return BinaryOperator::CreateAdd(WideX, NewC); - } - - return nullptr; -} - -Instruction *InstCombiner::foldAddWithConstant(BinaryOperator &Add) { - Value *Op0 = Add.getOperand(0), *Op1 = Add.getOperand(1); - Constant *Op1C; - if (!match(Op1, m_Constant(Op1C))) - return nullptr; - - if (Instruction *NV = foldBinOpIntoSelectOrPhi(Add)) - return NV; - - Value *X; - Constant *Op00C; - - // add (sub C1, X), C2 --> sub (add C1, C2), X - if (match(Op0, m_Sub(m_Constant(Op00C), m_Value(X)))) - return BinaryOperator::CreateSub(ConstantExpr::getAdd(Op00C, Op1C), X); - - Value *Y; - - // add (sub X, Y), -1 --> add (not Y), X - if (match(Op0, m_OneUse(m_Sub(m_Value(X), m_Value(Y)))) && - match(Op1, m_AllOnes())) - return BinaryOperator::CreateAdd(Builder.CreateNot(Y), X); - - // zext(bool) + C -> bool ? C + 1 : C - if (match(Op0, m_ZExt(m_Value(X))) && - X->getType()->getScalarSizeInBits() == 1) - return SelectInst::Create(X, AddOne(Op1C), Op1); - - // ~X + C --> (C-1) - X - if (match(Op0, m_Not(m_Value(X)))) - return BinaryOperator::CreateSub(SubOne(Op1C), X); - - const APInt *C; - if (!match(Op1, m_APInt(C))) - return nullptr; - - // (X | C2) + C --> (X | C2) ^ C2 iff (C2 == -C) - const APInt *C2; - if (match(Op0, m_Or(m_Value(), m_APInt(C2))) && *C2 == -*C) - return BinaryOperator::CreateXor(Op0, ConstantInt::get(Add.getType(), *C2)); - - if (C->isSignMask()) { - // If wrapping is not allowed, then the addition must set the sign bit: - // X + (signmask) --> X | signmask - if (Add.hasNoSignedWrap() || Add.hasNoUnsignedWrap()) - return BinaryOperator::CreateOr(Op0, Op1); - - // If wrapping is allowed, then the addition flips the sign bit of LHS: - // X + (signmask) --> X ^ signmask - return BinaryOperator::CreateXor(Op0, Op1); - } - - // Is this add the last step in a convoluted sext? - // add(zext(xor i16 X, -32768), -32768) --> sext X - Type *Ty = Add.getType(); - if (match(Op0, m_ZExt(m_Xor(m_Value(X), m_APInt(C2)))) && - C2->isMinSignedValue() && C2->sext(Ty->getScalarSizeInBits()) == *C) - return CastInst::Create(Instruction::SExt, X, Ty); - - if (C->isOneValue() && Op0->hasOneUse()) { - // add (sext i1 X), 1 --> zext (not X) - // TODO: The smallest IR representation is (select X, 0, 1), and that would - // not require the one-use check. But we need to remove a transform in - // visitSelect and make sure that IR value tracking for select is equal or - // better than for these ops. - if (match(Op0, m_SExt(m_Value(X))) && - X->getType()->getScalarSizeInBits() == 1) - return new ZExtInst(Builder.CreateNot(X), Ty); - - // Shifts and add used to flip and mask off the low bit: - // add (ashr (shl i32 X, 31), 31), 1 --> and (not X), 1 - const APInt *C3; - if (match(Op0, m_AShr(m_Shl(m_Value(X), m_APInt(C2)), m_APInt(C3))) && - C2 == C3 && *C2 == Ty->getScalarSizeInBits() - 1) { - Value *NotX = Builder.CreateNot(X); - return BinaryOperator::CreateAnd(NotX, ConstantInt::get(Ty, 1)); - } - } - - return nullptr; -} - -// Matches multiplication expression Op * C where C is a constant. Returns the -// constant value in C and the other operand in Op. Returns true if such a -// match is found. -static bool MatchMul(Value *E, Value *&Op, APInt &C) { - const APInt *AI; - if (match(E, m_Mul(m_Value(Op), m_APInt(AI)))) { - C = *AI; - return true; - } - if (match(E, m_Shl(m_Value(Op), m_APInt(AI)))) { - C = APInt(AI->getBitWidth(), 1); - C <<= *AI; - return true; - } - return false; -} - -// Matches remainder expression Op % C where C is a constant. Returns the -// constant value in C and the other operand in Op. Returns the signedness of -// the remainder operation in IsSigned. Returns true if such a match is -// found. -static bool MatchRem(Value *E, Value *&Op, APInt &C, bool &IsSigned) { - const APInt *AI; - IsSigned = false; - if (match(E, m_SRem(m_Value(Op), m_APInt(AI)))) { - IsSigned = true; - C = *AI; - return true; - } - if (match(E, m_URem(m_Value(Op), m_APInt(AI)))) { - C = *AI; - return true; - } - if (match(E, m_And(m_Value(Op), m_APInt(AI))) && (*AI + 1).isPowerOf2()) { - C = *AI + 1; - return true; - } - return false; -} - -// Matches division expression Op / C with the given signedness as indicated -// by IsSigned, where C is a constant. Returns the constant value in C and the -// other operand in Op. Returns true if such a match is found. -static bool MatchDiv(Value *E, Value *&Op, APInt &C, bool IsSigned) { - const APInt *AI; - if (IsSigned && match(E, m_SDiv(m_Value(Op), m_APInt(AI)))) { - C = *AI; - return true; - } - if (!IsSigned) { - if (match(E, m_UDiv(m_Value(Op), m_APInt(AI)))) { - C = *AI; - return true; - } - if (match(E, m_LShr(m_Value(Op), m_APInt(AI)))) { - C = APInt(AI->getBitWidth(), 1); - C <<= *AI; - return true; - } - } - return false; -} - -// Returns whether C0 * C1 with the given signedness overflows. -static bool MulWillOverflow(APInt &C0, APInt &C1, bool IsSigned) { - bool overflow; - if (IsSigned) - (void)C0.smul_ov(C1, overflow); - else - (void)C0.umul_ov(C1, overflow); - return overflow; -} - -// Simplifies X % C0 + (( X / C0 ) % C1) * C0 to X % (C0 * C1), where (C0 * C1) -// does not overflow. -Value *InstCombiner::SimplifyAddWithRemainder(BinaryOperator &I) { - Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); - Value *X, *MulOpV; - APInt C0, MulOpC; - bool IsSigned; - // Match I = X % C0 + MulOpV * C0 - if (((MatchRem(LHS, X, C0, IsSigned) && MatchMul(RHS, MulOpV, MulOpC)) || - (MatchRem(RHS, X, C0, IsSigned) && MatchMul(LHS, MulOpV, MulOpC))) && - C0 == MulOpC) { - Value *RemOpV; - APInt C1; - bool Rem2IsSigned; - // Match MulOpC = RemOpV % C1 - if (MatchRem(MulOpV, RemOpV, C1, Rem2IsSigned) && - IsSigned == Rem2IsSigned) { - Value *DivOpV; - APInt DivOpC; - // Match RemOpV = X / C0 - if (MatchDiv(RemOpV, DivOpV, DivOpC, IsSigned) && X == DivOpV && - C0 == DivOpC && !MulWillOverflow(C0, C1, IsSigned)) { - Value *NewDivisor = - ConstantInt::get(X->getType()->getContext(), C0 * C1); - return IsSigned ? Builder.CreateSRem(X, NewDivisor, "srem") - : Builder.CreateURem(X, NewDivisor, "urem"); - } - } - } - - return nullptr; -} - -/// Fold -/// (1 << NBits) - 1 -/// Into: -/// ~(-(1 << NBits)) -/// Because a 'not' is better for bit-tracking analysis and other transforms -/// than an 'add'. The new shl is always nsw, and is nuw if old `and` was. -static Instruction *canonicalizeLowbitMask(BinaryOperator &I, - InstCombiner::BuilderTy &Builder) { - Value *NBits; - if (!match(&I, m_Add(m_OneUse(m_Shl(m_One(), m_Value(NBits))), m_AllOnes()))) - return nullptr; - - Constant *MinusOne = Constant::getAllOnesValue(NBits->getType()); - Value *NotMask = Builder.CreateShl(MinusOne, NBits, "notmask"); - // Be wary of constant folding. - if (auto *BOp = dyn_cast<BinaryOperator>(NotMask)) { - // Always NSW. But NUW propagates from `add`. - BOp->setHasNoSignedWrap(); - BOp->setHasNoUnsignedWrap(I.hasNoUnsignedWrap()); - } - - return BinaryOperator::CreateNot(NotMask, I.getName()); -} - -static Instruction *foldToUnsignedSaturatedAdd(BinaryOperator &I) { - assert(I.getOpcode() == Instruction::Add && "Expecting add instruction"); - Type *Ty = I.getType(); - auto getUAddSat = [&]() { - return Intrinsic::getDeclaration(I.getModule(), Intrinsic::uadd_sat, Ty); - }; - - // add (umin X, ~Y), Y --> uaddsat X, Y - Value *X, *Y; - if (match(&I, m_c_Add(m_c_UMin(m_Value(X), m_Not(m_Value(Y))), - m_Deferred(Y)))) - return CallInst::Create(getUAddSat(), { X, Y }); - - // add (umin X, ~C), C --> uaddsat X, C - const APInt *C, *NotC; - if (match(&I, m_Add(m_UMin(m_Value(X), m_APInt(NotC)), m_APInt(C))) && - *C == ~*NotC) - return CallInst::Create(getUAddSat(), { X, ConstantInt::get(Ty, *C) }); - - return nullptr; -} - -Instruction *InstCombiner::visitAdd(BinaryOperator &I) { - if (Value *V = SimplifyAddInst(I.getOperand(0), I.getOperand(1), - I.hasNoSignedWrap(), I.hasNoUnsignedWrap(), - SQ.getWithInstruction(&I))) - return replaceInstUsesWith(I, V); - - if (SimplifyAssociativeOrCommutative(I)) - return &I; - - if (Instruction *X = foldVectorBinop(I)) - return X; - - // (A*B)+(A*C) -> A*(B+C) etc - if (Value *V = SimplifyUsingDistributiveLaws(I)) - return replaceInstUsesWith(I, V); - - if (Instruction *X = foldAddWithConstant(I)) - return X; - - if (Instruction *X = foldNoWrapAdd(I, Builder)) - return X; - - // FIXME: This should be moved into the above helper function to allow these - // transforms for general constant or constant splat vectors. - Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); - Type *Ty = I.getType(); - if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { - Value *XorLHS = nullptr; ConstantInt *XorRHS = nullptr; - if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) { - unsigned TySizeBits = Ty->getScalarSizeInBits(); - const APInt &RHSVal = CI->getValue(); - unsigned ExtendAmt = 0; - // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext. - // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext. - if (XorRHS->getValue() == -RHSVal) { - if (RHSVal.isPowerOf2()) - ExtendAmt = TySizeBits - RHSVal.logBase2() - 1; - else if (XorRHS->getValue().isPowerOf2()) - ExtendAmt = TySizeBits - XorRHS->getValue().logBase2() - 1; - } - - if (ExtendAmt) { - APInt Mask = APInt::getHighBitsSet(TySizeBits, ExtendAmt); - if (!MaskedValueIsZero(XorLHS, Mask, 0, &I)) - ExtendAmt = 0; - } - - if (ExtendAmt) { - Constant *ShAmt = ConstantInt::get(Ty, ExtendAmt); - Value *NewShl = Builder.CreateShl(XorLHS, ShAmt, "sext"); - return BinaryOperator::CreateAShr(NewShl, ShAmt); - } - - // If this is a xor that was canonicalized from a sub, turn it back into - // a sub and fuse this add with it. - if (LHS->hasOneUse() && (XorRHS->getValue()+1).isPowerOf2()) { - KnownBits LHSKnown = computeKnownBits(XorLHS, 0, &I); - if ((XorRHS->getValue() | LHSKnown.Zero).isAllOnesValue()) - return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI), - XorLHS); - } - // (X + signmask) + C could have gotten canonicalized to (X^signmask) + C, - // transform them into (X + (signmask ^ C)) - if (XorRHS->getValue().isSignMask()) - return BinaryOperator::CreateAdd(XorLHS, - ConstantExpr::getXor(XorRHS, CI)); - } - } - - if (Ty->isIntOrIntVectorTy(1)) - return BinaryOperator::CreateXor(LHS, RHS); - - // X + X --> X << 1 - if (LHS == RHS) { - auto *Shl = BinaryOperator::CreateShl(LHS, ConstantInt::get(Ty, 1)); - Shl->setHasNoSignedWrap(I.hasNoSignedWrap()); - Shl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap()); - return Shl; - } - - Value *A, *B; - if (match(LHS, m_Neg(m_Value(A)))) { - // -A + -B --> -(A + B) - if (match(RHS, m_Neg(m_Value(B)))) - return BinaryOperator::CreateNeg(Builder.CreateAdd(A, B)); - - // -A + B --> B - A - return BinaryOperator::CreateSub(RHS, A); - } - - // Canonicalize sext to zext for better value tracking potential. - // add A, sext(B) --> sub A, zext(B) - if (match(&I, m_c_Add(m_Value(A), m_OneUse(m_SExt(m_Value(B))))) && - B->getType()->isIntOrIntVectorTy(1)) - return BinaryOperator::CreateSub(A, Builder.CreateZExt(B, Ty)); - - // A + -B --> A - B - if (match(RHS, m_Neg(m_Value(B)))) - return BinaryOperator::CreateSub(LHS, B); - - if (Value *V = checkForNegativeOperand(I, Builder)) - return replaceInstUsesWith(I, V); - - // (A + 1) + ~B --> A - B - // ~B + (A + 1) --> A - B - // (~B + A) + 1 --> A - B - // (A + ~B) + 1 --> A - B - if (match(&I, m_c_BinOp(m_Add(m_Value(A), m_One()), m_Not(m_Value(B)))) || - match(&I, m_BinOp(m_c_Add(m_Not(m_Value(B)), m_Value(A)), m_One()))) - return BinaryOperator::CreateSub(A, B); - - // X % C0 + (( X / C0 ) % C1) * C0 => X % (C0 * C1) - if (Value *V = SimplifyAddWithRemainder(I)) return replaceInstUsesWith(I, V); - - // A+B --> A|B iff A and B have no bits set in common. - if (haveNoCommonBitsSet(LHS, RHS, DL, &AC, &I, &DT)) - return BinaryOperator::CreateOr(LHS, RHS); - - // FIXME: We already did a check for ConstantInt RHS above this. - // FIXME: Is this pattern covered by another fold? No regression tests fail on - // removal. - if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) { - // (X & FF00) + xx00 -> (X+xx00) & FF00 - Value *X; - ConstantInt *C2; - if (LHS->hasOneUse() && - match(LHS, m_And(m_Value(X), m_ConstantInt(C2))) && - CRHS->getValue() == (CRHS->getValue() & C2->getValue())) { - // See if all bits from the first bit set in the Add RHS up are included - // in the mask. First, get the rightmost bit. - const APInt &AddRHSV = CRHS->getValue(); - - // Form a mask of all bits from the lowest bit added through the top. - APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1)); - - // See if the and mask includes all of these bits. - APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue()); - - if (AddRHSHighBits == AddRHSHighBitsAnd) { - // Okay, the xform is safe. Insert the new add pronto. - Value *NewAdd = Builder.CreateAdd(X, CRHS, LHS->getName()); - return BinaryOperator::CreateAnd(NewAdd, C2); - } - } - } - - // add (select X 0 (sub n A)) A --> select X A n - { - SelectInst *SI = dyn_cast<SelectInst>(LHS); - Value *A = RHS; - if (!SI) { - SI = dyn_cast<SelectInst>(RHS); - A = LHS; - } - if (SI && SI->hasOneUse()) { - Value *TV = SI->getTrueValue(); - Value *FV = SI->getFalseValue(); - Value *N; - - // Can we fold the add into the argument of the select? - // We check both true and false select arguments for a matching subtract. - if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A)))) - // Fold the add into the true select value. - return SelectInst::Create(SI->getCondition(), N, A); - - if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A)))) - // Fold the add into the false select value. - return SelectInst::Create(SI->getCondition(), A, N); - } - } - - if (Instruction *Ext = narrowMathIfNoOverflow(I)) - return Ext; - - // (add (xor A, B) (and A, B)) --> (or A, B) - // (add (and A, B) (xor A, B)) --> (or A, B) - if (match(&I, m_c_BinOp(m_Xor(m_Value(A), m_Value(B)), - m_c_And(m_Deferred(A), m_Deferred(B))))) - return BinaryOperator::CreateOr(A, B); - - // (add (or A, B) (and A, B)) --> (add A, B) - // (add (and A, B) (or A, B)) --> (add A, B) - if (match(&I, m_c_BinOp(m_Or(m_Value(A), m_Value(B)), - m_c_And(m_Deferred(A), m_Deferred(B))))) { - I.setOperand(0, A); - I.setOperand(1, B); - return &I; - } - - // TODO(jingyue): Consider willNotOverflowSignedAdd and - // willNotOverflowUnsignedAdd to reduce the number of invocations of - // computeKnownBits. - bool Changed = false; - if (!I.hasNoSignedWrap() && willNotOverflowSignedAdd(LHS, RHS, I)) { - Changed = true; - I.setHasNoSignedWrap(true); - } - if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedAdd(LHS, RHS, I)) { - Changed = true; - I.setHasNoUnsignedWrap(true); - } - - if (Instruction *V = canonicalizeLowbitMask(I, Builder)) - return V; - - if (Instruction *SatAdd = foldToUnsignedSaturatedAdd(I)) - return SatAdd; - - return Changed ? &I : nullptr; -} - -/// Factor a common operand out of fadd/fsub of fmul/fdiv. -static Instruction *factorizeFAddFSub(BinaryOperator &I, - InstCombiner::BuilderTy &Builder) { - assert((I.getOpcode() == Instruction::FAdd || - I.getOpcode() == Instruction::FSub) && "Expecting fadd/fsub"); - assert(I.hasAllowReassoc() && I.hasNoSignedZeros() && - "FP factorization requires FMF"); - Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - Value *X, *Y, *Z; - bool IsFMul; - if ((match(Op0, m_OneUse(m_FMul(m_Value(X), m_Value(Z)))) && - match(Op1, m_OneUse(m_c_FMul(m_Value(Y), m_Specific(Z))))) || - (match(Op0, m_OneUse(m_FMul(m_Value(Z), m_Value(X)))) && - match(Op1, m_OneUse(m_c_FMul(m_Value(Y), m_Specific(Z)))))) - IsFMul = true; - else if (match(Op0, m_OneUse(m_FDiv(m_Value(X), m_Value(Z)))) && - match(Op1, m_OneUse(m_FDiv(m_Value(Y), m_Specific(Z))))) - IsFMul = false; - else - return nullptr; - - // (X * Z) + (Y * Z) --> (X + Y) * Z - // (X * Z) - (Y * Z) --> (X - Y) * Z - // (X / Z) + (Y / Z) --> (X + Y) / Z - // (X / Z) - (Y / Z) --> (X - Y) / Z - bool IsFAdd = I.getOpcode() == Instruction::FAdd; - Value *XY = IsFAdd ? Builder.CreateFAddFMF(X, Y, &I) - : Builder.CreateFSubFMF(X, Y, &I); - - // Bail out if we just created a denormal constant. - // TODO: This is copied from a previous implementation. Is it necessary? - const APFloat *C; - if (match(XY, m_APFloat(C)) && !C->isNormal()) - return nullptr; - - return IsFMul ? BinaryOperator::CreateFMulFMF(XY, Z, &I) - : BinaryOperator::CreateFDivFMF(XY, Z, &I); -} - -Instruction *InstCombiner::visitFAdd(BinaryOperator &I) { - if (Value *V = SimplifyFAddInst(I.getOperand(0), I.getOperand(1), - I.getFastMathFlags(), - SQ.getWithInstruction(&I))) - return replaceInstUsesWith(I, V); - - if (SimplifyAssociativeOrCommutative(I)) - return &I; - - if (Instruction *X = foldVectorBinop(I)) - return X; - - if (Instruction *FoldedFAdd = foldBinOpIntoSelectOrPhi(I)) - return FoldedFAdd; - - Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); - Value *X; - // (-X) + Y --> Y - X - if (match(LHS, m_FNeg(m_Value(X)))) - return BinaryOperator::CreateFSubFMF(RHS, X, &I); - // Y + (-X) --> Y - X - if (match(RHS, m_FNeg(m_Value(X)))) - return BinaryOperator::CreateFSubFMF(LHS, X, &I); - - // Check for (fadd double (sitofp x), y), see if we can merge this into an - // integer add followed by a promotion. - if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) { - Value *LHSIntVal = LHSConv->getOperand(0); - Type *FPType = LHSConv->getType(); - - // TODO: This check is overly conservative. In many cases known bits - // analysis can tell us that the result of the addition has less significant - // bits than the integer type can hold. - auto IsValidPromotion = [](Type *FTy, Type *ITy) { - Type *FScalarTy = FTy->getScalarType(); - Type *IScalarTy = ITy->getScalarType(); - - // Do we have enough bits in the significand to represent the result of - // the integer addition? - unsigned MaxRepresentableBits = - APFloat::semanticsPrecision(FScalarTy->getFltSemantics()); - return IScalarTy->getIntegerBitWidth() <= MaxRepresentableBits; - }; - - // (fadd double (sitofp x), fpcst) --> (sitofp (add int x, intcst)) - // ... if the constant fits in the integer value. This is useful for things - // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer - // requires a constant pool load, and generally allows the add to be better - // instcombined. - if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) - if (IsValidPromotion(FPType, LHSIntVal->getType())) { - Constant *CI = - ConstantExpr::getFPToSI(CFP, LHSIntVal->getType()); - if (LHSConv->hasOneUse() && - ConstantExpr::getSIToFP(CI, I.getType()) == CFP && - willNotOverflowSignedAdd(LHSIntVal, CI, I)) { - // Insert the new integer add. - Value *NewAdd = Builder.CreateNSWAdd(LHSIntVal, CI, "addconv"); - return new SIToFPInst(NewAdd, I.getType()); - } - } - - // (fadd double (sitofp x), (sitofp y)) --> (sitofp (add int x, y)) - if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) { - Value *RHSIntVal = RHSConv->getOperand(0); - // It's enough to check LHS types only because we require int types to - // be the same for this transform. - if (IsValidPromotion(FPType, LHSIntVal->getType())) { - // Only do this if x/y have the same type, if at least one of them has a - // single use (so we don't increase the number of int->fp conversions), - // and if the integer add will not overflow. - if (LHSIntVal->getType() == RHSIntVal->getType() && - (LHSConv->hasOneUse() || RHSConv->hasOneUse()) && - willNotOverflowSignedAdd(LHSIntVal, RHSIntVal, I)) { - // Insert the new integer add. - Value *NewAdd = Builder.CreateNSWAdd(LHSIntVal, RHSIntVal, "addconv"); - return new SIToFPInst(NewAdd, I.getType()); - } - } - } - } - - // Handle specials cases for FAdd with selects feeding the operation - if (Value *V = SimplifySelectsFeedingBinaryOp(I, LHS, RHS)) - return replaceInstUsesWith(I, V); - - if (I.hasAllowReassoc() && I.hasNoSignedZeros()) { - if (Instruction *F = factorizeFAddFSub(I, Builder)) - return F; - if (Value *V = FAddCombine(Builder).simplify(&I)) - return replaceInstUsesWith(I, V); - } - - return nullptr; -} - -/// Optimize pointer differences into the same array into a size. Consider: -/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer -/// operands to the ptrtoint instructions for the LHS/RHS of the subtract. -Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS, - Type *Ty) { - // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize - // this. - bool Swapped = false; - GEPOperator *GEP1 = nullptr, *GEP2 = nullptr; - - // For now we require one side to be the base pointer "A" or a constant - // GEP derived from it. - if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) { - // (gep X, ...) - X - if (LHSGEP->getOperand(0) == RHS) { - GEP1 = LHSGEP; - Swapped = false; - } else if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) { - // (gep X, ...) - (gep X, ...) - if (LHSGEP->getOperand(0)->stripPointerCasts() == - RHSGEP->getOperand(0)->stripPointerCasts()) { - GEP2 = RHSGEP; - GEP1 = LHSGEP; - Swapped = false; - } - } - } - - if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) { - // X - (gep X, ...) - if (RHSGEP->getOperand(0) == LHS) { - GEP1 = RHSGEP; - Swapped = true; - } else if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) { - // (gep X, ...) - (gep X, ...) - if (RHSGEP->getOperand(0)->stripPointerCasts() == - LHSGEP->getOperand(0)->stripPointerCasts()) { - GEP2 = LHSGEP; - GEP1 = RHSGEP; - Swapped = true; - } - } - } - - if (!GEP1) - // No GEP found. - return nullptr; - - if (GEP2) { - // (gep X, ...) - (gep X, ...) - // - // Avoid duplicating the arithmetic if there are more than one non-constant - // indices between the two GEPs and either GEP has a non-constant index and - // multiple users. If zero non-constant index, the result is a constant and - // there is no duplication. If one non-constant index, the result is an add - // or sub with a constant, which is no larger than the original code, and - // there's no duplicated arithmetic, even if either GEP has multiple - // users. If more than one non-constant indices combined, as long as the GEP - // with at least one non-constant index doesn't have multiple users, there - // is no duplication. - unsigned NumNonConstantIndices1 = GEP1->countNonConstantIndices(); - unsigned NumNonConstantIndices2 = GEP2->countNonConstantIndices(); - if (NumNonConstantIndices1 + NumNonConstantIndices2 > 1 && - ((NumNonConstantIndices1 > 0 && !GEP1->hasOneUse()) || - (NumNonConstantIndices2 > 0 && !GEP2->hasOneUse()))) { - return nullptr; - } - } - - // Emit the offset of the GEP and an intptr_t. - Value *Result = EmitGEPOffset(GEP1); - - // If we had a constant expression GEP on the other side offsetting the - // pointer, subtract it from the offset we have. - if (GEP2) { - Value *Offset = EmitGEPOffset(GEP2); - Result = Builder.CreateSub(Result, Offset); - } - - // If we have p - gep(p, ...) then we have to negate the result. - if (Swapped) - Result = Builder.CreateNeg(Result, "diff.neg"); - - return Builder.CreateIntCast(Result, Ty, true); -} - -Instruction *InstCombiner::visitSub(BinaryOperator &I) { - if (Value *V = SimplifySubInst(I.getOperand(0), I.getOperand(1), - I.hasNoSignedWrap(), I.hasNoUnsignedWrap(), - SQ.getWithInstruction(&I))) - return replaceInstUsesWith(I, V); - - if (Instruction *X = foldVectorBinop(I)) - return X; - - // (A*B)-(A*C) -> A*(B-C) etc - if (Value *V = SimplifyUsingDistributiveLaws(I)) - return replaceInstUsesWith(I, V); - - // If this is a 'B = x-(-A)', change to B = x+A. - Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = dyn_castNegVal(Op1)) { - BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V); - - if (const auto *BO = dyn_cast<BinaryOperator>(Op1)) { - assert(BO->getOpcode() == Instruction::Sub && - "Expected a subtraction operator!"); - if (BO->hasNoSignedWrap() && I.hasNoSignedWrap()) - Res->setHasNoSignedWrap(true); - } else { - if (cast<Constant>(Op1)->isNotMinSignedValue() && I.hasNoSignedWrap()) - Res->setHasNoSignedWrap(true); - } - - return Res; - } - - if (I.getType()->isIntOrIntVectorTy(1)) - return BinaryOperator::CreateXor(Op0, Op1); - - // Replace (-1 - A) with (~A). - if (match(Op0, m_AllOnes())) - return BinaryOperator::CreateNot(Op1); - - // (~X) - (~Y) --> Y - X - Value *X, *Y; - if (match(Op0, m_Not(m_Value(X))) && match(Op1, m_Not(m_Value(Y)))) - return BinaryOperator::CreateSub(Y, X); - - // (X + -1) - Y --> ~Y + X - if (match(Op0, m_OneUse(m_Add(m_Value(X), m_AllOnes())))) - return BinaryOperator::CreateAdd(Builder.CreateNot(Op1), X); - - // Y - (X + 1) --> ~X + Y - if (match(Op1, m_OneUse(m_Add(m_Value(X), m_One())))) - return BinaryOperator::CreateAdd(Builder.CreateNot(X), Op0); - - // Y - ~X --> (X + 1) + Y - if (match(Op1, m_OneUse(m_Not(m_Value(X))))) { - return BinaryOperator::CreateAdd( - Builder.CreateAdd(Op0, ConstantInt::get(I.getType(), 1)), X); - } - - if (Constant *C = dyn_cast<Constant>(Op0)) { - bool IsNegate = match(C, m_ZeroInt()); - Value *X; - if (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) { - // 0 - (zext bool) --> sext bool - // C - (zext bool) --> bool ? C - 1 : C - if (IsNegate) - return CastInst::CreateSExtOrBitCast(X, I.getType()); - return SelectInst::Create(X, SubOne(C), C); - } - if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) { - // 0 - (sext bool) --> zext bool - // C - (sext bool) --> bool ? C + 1 : C - if (IsNegate) - return CastInst::CreateZExtOrBitCast(X, I.getType()); - return SelectInst::Create(X, AddOne(C), C); - } - - // C - ~X == X + (1+C) - if (match(Op1, m_Not(m_Value(X)))) - return BinaryOperator::CreateAdd(X, AddOne(C)); - - // Try to fold constant sub into select arguments. - if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) - if (Instruction *R = FoldOpIntoSelect(I, SI)) - return R; - - // Try to fold constant sub into PHI values. - if (PHINode *PN = dyn_cast<PHINode>(Op1)) - if (Instruction *R = foldOpIntoPhi(I, PN)) - return R; - - Constant *C2; - - // C-(C2-X) --> X+(C-C2) - if (match(Op1, m_Sub(m_Constant(C2), m_Value(X)))) - return BinaryOperator::CreateAdd(X, ConstantExpr::getSub(C, C2)); - - // C-(X+C2) --> (C-C2)-X - if (match(Op1, m_Add(m_Value(X), m_Constant(C2)))) - return BinaryOperator::CreateSub(ConstantExpr::getSub(C, C2), X); - } - - const APInt *Op0C; - if (match(Op0, m_APInt(Op0C))) { - unsigned BitWidth = I.getType()->getScalarSizeInBits(); - - // -(X >>u 31) -> (X >>s 31) - // -(X >>s 31) -> (X >>u 31) - if (Op0C->isNullValue()) { - Value *X; - const APInt *ShAmt; - if (match(Op1, m_LShr(m_Value(X), m_APInt(ShAmt))) && - *ShAmt == BitWidth - 1) { - Value *ShAmtOp = cast<Instruction>(Op1)->getOperand(1); - return BinaryOperator::CreateAShr(X, ShAmtOp); - } - if (match(Op1, m_AShr(m_Value(X), m_APInt(ShAmt))) && - *ShAmt == BitWidth - 1) { - Value *ShAmtOp = cast<Instruction>(Op1)->getOperand(1); - return BinaryOperator::CreateLShr(X, ShAmtOp); - } - - if (Op1->hasOneUse()) { - Value *LHS, *RHS; - SelectPatternFlavor SPF = matchSelectPattern(Op1, LHS, RHS).Flavor; - if (SPF == SPF_ABS || SPF == SPF_NABS) { - // This is a negate of an ABS/NABS pattern. Just swap the operands - // of the select. - SelectInst *SI = cast<SelectInst>(Op1); - Value *TrueVal = SI->getTrueValue(); - Value *FalseVal = SI->getFalseValue(); - SI->setTrueValue(FalseVal); - SI->setFalseValue(TrueVal); - // Don't swap prof metadata, we didn't change the branch behavior. - return replaceInstUsesWith(I, SI); - } - } - } - - // Turn this into a xor if LHS is 2^n-1 and the remaining bits are known - // zero. - if (Op0C->isMask()) { - KnownBits RHSKnown = computeKnownBits(Op1, 0, &I); - if ((*Op0C | RHSKnown.Zero).isAllOnesValue()) - return BinaryOperator::CreateXor(Op1, Op0); - } - } - - { - Value *Y; - // X-(X+Y) == -Y X-(Y+X) == -Y - if (match(Op1, m_c_Add(m_Specific(Op0), m_Value(Y)))) - return BinaryOperator::CreateNeg(Y); - - // (X-Y)-X == -Y - if (match(Op0, m_Sub(m_Specific(Op1), m_Value(Y)))) - return BinaryOperator::CreateNeg(Y); - } - - // (sub (or A, B), (xor A, B)) --> (and A, B) - { - Value *A, *B; - if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && - match(Op0, m_c_Or(m_Specific(A), m_Specific(B)))) - return BinaryOperator::CreateAnd(A, B); - } - - { - Value *Y; - // ((X | Y) - X) --> (~X & Y) - if (match(Op0, m_OneUse(m_c_Or(m_Value(Y), m_Specific(Op1))))) - return BinaryOperator::CreateAnd( - Y, Builder.CreateNot(Op1, Op1->getName() + ".not")); - } - - if (Op1->hasOneUse()) { - Value *X = nullptr, *Y = nullptr, *Z = nullptr; - Constant *C = nullptr; - - // (X - (Y - Z)) --> (X + (Z - Y)). - if (match(Op1, m_Sub(m_Value(Y), m_Value(Z)))) - return BinaryOperator::CreateAdd(Op0, - Builder.CreateSub(Z, Y, Op1->getName())); - - // (X - (X & Y)) --> (X & ~Y) - if (match(Op1, m_c_And(m_Value(Y), m_Specific(Op0)))) - return BinaryOperator::CreateAnd(Op0, - Builder.CreateNot(Y, Y->getName() + ".not")); - - // 0 - (X sdiv C) -> (X sdiv -C) provided the negation doesn't overflow. - // TODO: This could be extended to match arbitrary vector constants. - const APInt *DivC; - if (match(Op0, m_Zero()) && match(Op1, m_SDiv(m_Value(X), m_APInt(DivC))) && - !DivC->isMinSignedValue() && *DivC != 1) { - Constant *NegDivC = ConstantInt::get(I.getType(), -(*DivC)); - Instruction *BO = BinaryOperator::CreateSDiv(X, NegDivC); - BO->setIsExact(cast<BinaryOperator>(Op1)->isExact()); - return BO; - } - - // 0 - (X << Y) -> (-X << Y) when X is freely negatable. - if (match(Op1, m_Shl(m_Value(X), m_Value(Y))) && match(Op0, m_Zero())) - if (Value *XNeg = dyn_castNegVal(X)) - return BinaryOperator::CreateShl(XNeg, Y); - - // Subtracting -1/0 is the same as adding 1/0: - // sub [nsw] Op0, sext(bool Y) -> add [nsw] Op0, zext(bool Y) - // 'nuw' is dropped in favor of the canonical form. - if (match(Op1, m_SExt(m_Value(Y))) && - Y->getType()->getScalarSizeInBits() == 1) { - Value *Zext = Builder.CreateZExt(Y, I.getType()); - BinaryOperator *Add = BinaryOperator::CreateAdd(Op0, Zext); - Add->setHasNoSignedWrap(I.hasNoSignedWrap()); - return Add; - } - - // X - A*-B -> X + A*B - // X - -A*B -> X + A*B - Value *A, *B; - if (match(Op1, m_c_Mul(m_Value(A), m_Neg(m_Value(B))))) - return BinaryOperator::CreateAdd(Op0, Builder.CreateMul(A, B)); - - // X - A*C -> X + A*-C - // No need to handle commuted multiply because multiply handling will - // ensure constant will be move to the right hand side. - if (match(Op1, m_Mul(m_Value(A), m_Constant(C))) && !isa<ConstantExpr>(C)) { - Value *NewMul = Builder.CreateMul(A, ConstantExpr::getNeg(C)); - return BinaryOperator::CreateAdd(Op0, NewMul); - } - } - - { - // ~A - Min/Max(~A, O) -> Max/Min(A, ~O) - A - // ~A - Min/Max(O, ~A) -> Max/Min(A, ~O) - A - // Min/Max(~A, O) - ~A -> A - Max/Min(A, ~O) - // Min/Max(O, ~A) - ~A -> A - Max/Min(A, ~O) - // So long as O here is freely invertible, this will be neutral or a win. - Value *LHS, *RHS, *A; - Value *NotA = Op0, *MinMax = Op1; - SelectPatternFlavor SPF = matchSelectPattern(MinMax, LHS, RHS).Flavor; - if (!SelectPatternResult::isMinOrMax(SPF)) { - NotA = Op1; - MinMax = Op0; - SPF = matchSelectPattern(MinMax, LHS, RHS).Flavor; - } - if (SelectPatternResult::isMinOrMax(SPF) && - match(NotA, m_Not(m_Value(A))) && (NotA == LHS || NotA == RHS)) { - if (NotA == LHS) - std::swap(LHS, RHS); - // LHS is now O above and expected to have at least 2 uses (the min/max) - // NotA is epected to have 2 uses from the min/max and 1 from the sub. - if (IsFreeToInvert(LHS, !LHS->hasNUsesOrMore(3)) && - !NotA->hasNUsesOrMore(4)) { - // Note: We don't generate the inverse max/min, just create the not of - // it and let other folds do the rest. - Value *Not = Builder.CreateNot(MinMax); - if (NotA == Op0) - return BinaryOperator::CreateSub(Not, A); - else - return BinaryOperator::CreateSub(A, Not); - } - } - } - - // Optimize pointer differences into the same array into a size. Consider: - // &A[10] - &A[0]: we should compile this to "10". - Value *LHSOp, *RHSOp; - if (match(Op0, m_PtrToInt(m_Value(LHSOp))) && - match(Op1, m_PtrToInt(m_Value(RHSOp)))) - if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) - return replaceInstUsesWith(I, Res); - - // trunc(p)-trunc(q) -> trunc(p-q) - if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) && - match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp))))) - if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) - return replaceInstUsesWith(I, Res); - - // Canonicalize a shifty way to code absolute value to the common pattern. - // There are 2 potential commuted variants. - // We're relying on the fact that we only do this transform when the shift has - // exactly 2 uses and the xor has exactly 1 use (otherwise, we might increase - // instructions). - Value *A; - const APInt *ShAmt; - Type *Ty = I.getType(); - if (match(Op1, m_AShr(m_Value(A), m_APInt(ShAmt))) && - Op1->hasNUses(2) && *ShAmt == Ty->getScalarSizeInBits() - 1 && - match(Op0, m_OneUse(m_c_Xor(m_Specific(A), m_Specific(Op1))))) { - // B = ashr i32 A, 31 ; smear the sign bit - // sub (xor A, B), B ; flip bits if negative and subtract -1 (add 1) - // --> (A < 0) ? -A : A - Value *Cmp = Builder.CreateICmpSLT(A, ConstantInt::getNullValue(Ty)); - // Copy the nuw/nsw flags from the sub to the negate. - Value *Neg = Builder.CreateNeg(A, "", I.hasNoUnsignedWrap(), - I.hasNoSignedWrap()); - return SelectInst::Create(Cmp, Neg, A); - } - - if (Instruction *Ext = narrowMathIfNoOverflow(I)) - return Ext; - - bool Changed = false; - if (!I.hasNoSignedWrap() && willNotOverflowSignedSub(Op0, Op1, I)) { - Changed = true; - I.setHasNoSignedWrap(true); - } - if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedSub(Op0, Op1, I)) { - Changed = true; - I.setHasNoUnsignedWrap(true); - } - - return Changed ? &I : nullptr; -} - -/// This eliminates floating-point negation in either 'fneg(X)' or -/// 'fsub(-0.0, X)' form by combining into a constant operand. -static Instruction *foldFNegIntoConstant(Instruction &I) { - Value *X; - Constant *C; - - // Fold negation into constant operand. This is limited with one-use because - // fneg is assumed better for analysis and cheaper in codegen than fmul/fdiv. - // -(X * C) --> X * (-C) - // FIXME: It's arguable whether these should be m_OneUse or not. The current - // belief is that the FNeg allows for better reassociation opportunities. - if (match(&I, m_FNeg(m_OneUse(m_FMul(m_Value(X), m_Constant(C)))))) - return BinaryOperator::CreateFMulFMF(X, ConstantExpr::getFNeg(C), &I); - // -(X / C) --> X / (-C) - if (match(&I, m_FNeg(m_OneUse(m_FDiv(m_Value(X), m_Constant(C)))))) - return BinaryOperator::CreateFDivFMF(X, ConstantExpr::getFNeg(C), &I); - // -(C / X) --> (-C) / X - if (match(&I, m_FNeg(m_OneUse(m_FDiv(m_Constant(C), m_Value(X)))))) - return BinaryOperator::CreateFDivFMF(ConstantExpr::getFNeg(C), X, &I); - - return nullptr; -} - -Instruction *InstCombiner::visitFNeg(UnaryOperator &I) { - Value *Op = I.getOperand(0); - - if (Value *V = SimplifyFNegInst(Op, I.getFastMathFlags(), - SQ.getWithInstruction(&I))) - return replaceInstUsesWith(I, V); - - if (Instruction *X = foldFNegIntoConstant(I)) - return X; - - Value *X, *Y; - - // If we can ignore the sign of zeros: -(X - Y) --> (Y - X) - if (I.hasNoSignedZeros() && - match(Op, m_OneUse(m_FSub(m_Value(X), m_Value(Y))))) - return BinaryOperator::CreateFSubFMF(Y, X, &I); - - return nullptr; -} - -Instruction *InstCombiner::visitFSub(BinaryOperator &I) { - if (Value *V = SimplifyFSubInst(I.getOperand(0), I.getOperand(1), - I.getFastMathFlags(), - SQ.getWithInstruction(&I))) - return replaceInstUsesWith(I, V); - - if (Instruction *X = foldVectorBinop(I)) - return X; - - // Subtraction from -0.0 is the canonical form of fneg. - // fsub nsz 0, X ==> fsub nsz -0.0, X - Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (I.hasNoSignedZeros() && match(Op0, m_PosZeroFP())) - return BinaryOperator::CreateFNegFMF(Op1, &I); - - if (Instruction *X = foldFNegIntoConstant(I)) - return X; - - Value *X, *Y; - Constant *C; - - // If Op0 is not -0.0 or we can ignore -0.0: Z - (X - Y) --> Z + (Y - X) - // Canonicalize to fadd to make analysis easier. - // This can also help codegen because fadd is commutative. - // Note that if this fsub was really an fneg, the fadd with -0.0 will get - // killed later. We still limit that particular transform with 'hasOneUse' - // because an fneg is assumed better/cheaper than a generic fsub. - if (I.hasNoSignedZeros() || CannotBeNegativeZero(Op0, SQ.TLI)) { - if (match(Op1, m_OneUse(m_FSub(m_Value(X), m_Value(Y))))) { - Value *NewSub = Builder.CreateFSubFMF(Y, X, &I); - return BinaryOperator::CreateFAddFMF(Op0, NewSub, &I); - } - } - - if (isa<Constant>(Op0)) - if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) - if (Instruction *NV = FoldOpIntoSelect(I, SI)) - return NV; - - // X - C --> X + (-C) - // But don't transform constant expressions because there's an inverse fold - // for X + (-Y) --> X - Y. - if (match(Op1, m_Constant(C)) && !isa<ConstantExpr>(Op1)) - return BinaryOperator::CreateFAddFMF(Op0, ConstantExpr::getFNeg(C), &I); - - // X - (-Y) --> X + Y - if (match(Op1, m_FNeg(m_Value(Y)))) - return BinaryOperator::CreateFAddFMF(Op0, Y, &I); - - // Similar to above, but look through a cast of the negated value: - // X - (fptrunc(-Y)) --> X + fptrunc(Y) - Type *Ty = I.getType(); - if (match(Op1, m_OneUse(m_FPTrunc(m_FNeg(m_Value(Y)))))) - return BinaryOperator::CreateFAddFMF(Op0, Builder.CreateFPTrunc(Y, Ty), &I); - - // X - (fpext(-Y)) --> X + fpext(Y) - if (match(Op1, m_OneUse(m_FPExt(m_FNeg(m_Value(Y)))))) - return BinaryOperator::CreateFAddFMF(Op0, Builder.CreateFPExt(Y, Ty), &I); - - // Handle special cases for FSub with selects feeding the operation - if (Value *V = SimplifySelectsFeedingBinaryOp(I, Op0, Op1)) - return replaceInstUsesWith(I, V); - - if (I.hasAllowReassoc() && I.hasNoSignedZeros()) { - // (Y - X) - Y --> -X - if (match(Op0, m_FSub(m_Specific(Op1), m_Value(X)))) - return BinaryOperator::CreateFNegFMF(X, &I); - - // Y - (X + Y) --> -X - // Y - (Y + X) --> -X - if (match(Op1, m_c_FAdd(m_Specific(Op0), m_Value(X)))) - return BinaryOperator::CreateFNegFMF(X, &I); - - // (X * C) - X --> X * (C - 1.0) - if (match(Op0, m_FMul(m_Specific(Op1), m_Constant(C)))) { - Constant *CSubOne = ConstantExpr::getFSub(C, ConstantFP::get(Ty, 1.0)); - return BinaryOperator::CreateFMulFMF(Op1, CSubOne, &I); - } - // X - (X * C) --> X * (1.0 - C) - if (match(Op1, m_FMul(m_Specific(Op0), m_Constant(C)))) { - Constant *OneSubC = ConstantExpr::getFSub(ConstantFP::get(Ty, 1.0), C); - return BinaryOperator::CreateFMulFMF(Op0, OneSubC, &I); - } - - if (Instruction *F = factorizeFAddFSub(I, Builder)) - return F; - - // TODO: This performs reassociative folds for FP ops. Some fraction of the - // functionality has been subsumed by simple pattern matching here and in - // InstSimplify. We should let a dedicated reassociation pass handle more - // complex pattern matching and remove this from InstCombine. - if (Value *V = FAddCombine(Builder).simplify(&I)) - return replaceInstUsesWith(I, V); - } - - return nullptr; -} |