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+//===- 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;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-12-08 21:29:20 +0000