C++ BinaryOperator::setIsExact方法代码示例

/// Annotate the Shr in (X << IVOperand) >> C as exact using the
/// information from the IV's range. Returns true if anything changed, false
/// otherwise.
bool SimplifyIndvar::strengthenRightShift(BinaryOperator *BO,
                                          Value *IVOperand) {
  using namespace llvm::PatternMatch;

  if (BO->getOpcode() == Instruction::Shl) {
    bool Changed = false;
    ConstantRange IVRange = SE->getUnsignedRange(SE->getSCEV(IVOperand));
    for (auto *U : BO->users()) {
      const APInt *C;
      if (match(U,
                m_AShr(m_Shl(m_Value(), m_Specific(IVOperand)), m_APInt(C))) ||
          match(U,
                m_LShr(m_Shl(m_Value(), m_Specific(IVOperand)), m_APInt(C)))) {
        BinaryOperator *Shr = cast<BinaryOperator>(U);
        if (!Shr->isExact() && IVRange.getUnsignedMin().uge(*C)) {
          Shr->setIsExact(true);
          Changed = true;
        }
      }
    }
    return Changed;
  }

  return false;
}

// X udiv 2^C -> X >> C
static Instruction *foldUDivPow2Cst(Value *Op0, Value *Op1,
                                    const BinaryOperator &I, InstCombiner &IC) {
  const APInt &C = cast<Constant>(Op1)->getUniqueInteger();
  BinaryOperator *LShr = BinaryOperator::CreateLShr(
      Op0, ConstantInt::get(Op0->getType(), C.logBase2()));
  if (I.isExact()) LShr->setIsExact();
  return LShr;
}

TEST(CloneInstruction, Exact) {
  LLVMContext context;
  Value *V = new Argument(Type::getInt32Ty(context));

  BinaryOperator *SDiv = BinaryOperator::Create(Instruction::SDiv, V, V);
  EXPECT_FALSE(cast<BinaryOperator>(SDiv->clone())->isExact());

  SDiv->setIsExact(true);
  EXPECT_TRUE(cast<BinaryOperator>(SDiv->clone())->isExact());
}

Value *AMDGPUCodeGenPrepare::copyFlags(
    const BinaryOperator &I, Value *V) const {
  assert(isa<BinaryOperator>(V) && "V must be binary operation");

  BinaryOperator *BinOp = cast<BinaryOperator>(V);
  if (isa<OverflowingBinaryOperator>(BinOp)) {
    BinOp->setHasNoSignedWrap(I.hasNoSignedWrap());
    BinOp->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
  } else if (isa<PossiblyExactOperator>(BinOp))
    BinOp->setIsExact(I.isExact());

  return V;
}

/// FoldSelectIntoOp - Try fold the select into one of the operands to
/// facilitate further optimization.
Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
                                            Value *FalseVal) {
  // See the comment above GetSelectFoldableOperands for a description of the
  // transformation we are doing here.
  if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
    if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
        !isa<Constant>(FalseVal)) {
      if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
        unsigned OpToFold = 0;
        if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
          OpToFold = 1;
        } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
          OpToFold = 2;
        }

        if (OpToFold) {
          Constant *C = GetSelectFoldableConstant(TVI);
          Value *OOp = TVI->getOperand(2-OpToFold);
          // Avoid creating select between 2 constants unless it's selecting
          // between 0, 1 and -1.
          if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
            Value *NewSel = Builder->CreateSelect(SI.getCondition(), OOp, C);
            NewSel->takeName(TVI);
            BinaryOperator *TVI_BO = cast<BinaryOperator>(TVI);
            BinaryOperator *BO = BinaryOperator::Create(TVI_BO->getOpcode(),
                                                        FalseVal, NewSel);
            if (isa<PossiblyExactOperator>(BO))
              BO->setIsExact(TVI_BO->isExact());
            if (isa<OverflowingBinaryOperator>(BO)) {
              BO->setHasNoUnsignedWrap(TVI_BO->hasNoUnsignedWrap());
              BO->setHasNoSignedWrap(TVI_BO->hasNoSignedWrap());
            }
            return BO;
          }
        }
      }
    }
  }

  if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
    if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
        !isa<Constant>(TrueVal)) {
      if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
        unsigned OpToFold = 0;
        if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
          OpToFold = 1;
        } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
          OpToFold = 2;
        }

        if (OpToFold) {
          Constant *C = GetSelectFoldableConstant(FVI);
          Value *OOp = FVI->getOperand(2-OpToFold);
          // Avoid creating select between 2 constants unless it's selecting
          // between 0, 1 and -1.
          if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
            Value *NewSel = Builder->CreateSelect(SI.getCondition(), C, OOp);
            NewSel->takeName(FVI);
            BinaryOperator *FVI_BO = cast<BinaryOperator>(FVI);
            BinaryOperator *BO = BinaryOperator::Create(FVI_BO->getOpcode(),
                                                        TrueVal, NewSel);
            if (isa<PossiblyExactOperator>(BO))
              BO->setIsExact(FVI_BO->isExact());
            if (isa<OverflowingBinaryOperator>(BO)) {
              BO->setHasNoUnsignedWrap(FVI_BO->hasNoUnsignedWrap());
              BO->setHasNoSignedWrap(FVI_BO->hasNoSignedWrap());
            }
            return BO;
          }
        }
      }
    }
  }

  return nullptr;
}

/// Rebuild a new instruction just like 'I' but with the new operands given.
/// In the event of type mismatch, the type of the operands is correct.
static Value *BuildNew(Instruction *I, ArrayRef<Value*> NewOps) {
  // We don't want to use the IRBuilder here because we want the replacement
  // instructions to appear next to 'I', not the builder's insertion point.
  switch (I->getOpcode()) {
    case Instruction::Add:
    case Instruction::FAdd:
    case Instruction::Sub:
    case Instruction::FSub:
    case Instruction::Mul:
    case Instruction::FMul:
    case Instruction::UDiv:
    case Instruction::SDiv:
    case Instruction::FDiv:
    case Instruction::URem:
    case Instruction::SRem:
    case Instruction::FRem:
    case Instruction::Shl:
    case Instruction::LShr:
    case Instruction::AShr:
    case Instruction::And:
    case Instruction::Or:
    case Instruction::Xor: {
      BinaryOperator *BO = cast<BinaryOperator>(I);
      assert(NewOps.size() == 2 && "binary operator with #ops != 2");
      BinaryOperator *New =
          BinaryOperator::Create(cast<BinaryOperator>(I)->getOpcode(),
                                 NewOps[0], NewOps[1], "", BO);
      if (isa<OverflowingBinaryOperator>(BO)) {
        New->setHasNoUnsignedWrap(BO->hasNoUnsignedWrap());
        New->setHasNoSignedWrap(BO->hasNoSignedWrap());
      }
      if (isa<PossiblyExactOperator>(BO)) {
        New->setIsExact(BO->isExact());
      }
      return New;
    }
    case Instruction::ICmp:
      assert(NewOps.size() == 2 && "icmp with #ops != 2");
      return new ICmpInst(I, cast<ICmpInst>(I)->getPredicate(),
                          NewOps[0], NewOps[1]);
    case Instruction::FCmp:
      assert(NewOps.size() == 2 && "fcmp with #ops != 2");
      return new FCmpInst(I, cast<FCmpInst>(I)->getPredicate(),
                          NewOps[0], NewOps[1]);
    case Instruction::Trunc:
    case Instruction::ZExt:
    case Instruction::SExt:
    case Instruction::FPToUI:
    case Instruction::FPToSI:
    case Instruction::UIToFP:
    case Instruction::SIToFP:
    case Instruction::FPTrunc:
    case Instruction::FPExt: {
      // It's possible that the mask has a different number of elements from
      // the original cast. We recompute the destination type to match the mask.
      Type *DestTy =
          VectorType::get(I->getType()->getScalarType(),
                          NewOps[0]->getType()->getVectorNumElements());
      assert(NewOps.size() == 1 && "cast with #ops != 1");
      return CastInst::Create(cast<CastInst>(I)->getOpcode(), NewOps[0], DestTy,
                              "", I);
    }
    case Instruction::GetElementPtr: {
      Value *Ptr = NewOps[0];
      ArrayRef<Value*> Idx = NewOps.slice(1);
      GetElementPtrInst *GEP = GetElementPtrInst::Create(Ptr, Idx, "", I);
      GEP->setIsInBounds(cast<GetElementPtrInst>(I)->isInBounds());
      return GEP;
    }
  }
  llvm_unreachable("failed to rebuild vector instructions");
}

Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);

  if (Value *V = SimplifyUDivInst(Op0, Op1, TD))
    return ReplaceInstUsesWith(I, V);

  // Handle the integer div common cases
  if (Instruction *Common = commonIDivTransforms(I))
    return Common;
  
  { 
    // X udiv 2^C -> X >> C
    // Check to see if this is an unsigned division with an exact power of 2,
    // if so, convert to a right shift.
    const APInt *C;
    if (match(Op1, m_Power2(C))) {
      BinaryOperator *LShr =
      BinaryOperator::CreateLShr(Op0, 
                                 ConstantInt::get(Op0->getType(), 
                                                  C->logBase2()));
      if (I.isExact()) LShr->setIsExact();
      return LShr;
    }
  }

  if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
    // X udiv C, where C >= signbit
    if (C->getValue().isNegative()) {
      Value *IC = Builder->CreateICmpULT(Op0, C);
      return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
                                ConstantInt::get(I.getType(), 1));
    }
  }

  // X udiv (C1 << N), where C1 is "1<<C2"  -->  X >> (N+C2)
  { const APInt *CI; Value *N;
    if (match(Op1, m_Shl(m_Power2(CI), m_Value(N)))) {
      if (*CI != 1)
        N = Builder->CreateAdd(N, ConstantInt::get(I.getType(),CI->logBase2()));
      if (I.isExact())
        return BinaryOperator::CreateExactLShr(Op0, N);
      return BinaryOperator::CreateLShr(Op0, N);
    }
  }
  
  // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
  // where C1&C2 are powers of two.
  { Value *Cond; const APInt *C1, *C2;
    if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) {
      // Construct the "on true" case of the select
      Value *TSI = Builder->CreateLShr(Op0, C1->logBase2(), Op1->getName()+".t",
                                       I.isExact());
  
      // Construct the "on false" case of the select
      Value *FSI = Builder->CreateLShr(Op0, C2->logBase2(), Op1->getName()+".f",
                                       I.isExact());
      
      // construct the select instruction and return it.
      return SelectInst::Create(Cond, TSI, FSI);
    }
  }

  // (zext A) udiv (zext B) --> zext (A udiv B)
  if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
    if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
      return new ZExtInst(Builder->CreateUDiv(ZOp0->getOperand(0), ZOp1, "div",
                                              I.isExact()),
                          I.getType());

  return 0;
}

//.........这里部分代码省略.........
      Op = Instruction::Add;
      break;
    case 1:
      Op = Instruction::Sub;
      break;
    case 2:
      Op = Instruction::Mul;
      break;
    case 3:
      Op = Instruction::SDiv;
      break;
    case 4:
      Op = Instruction::UDiv;
      break;
    case 5:
      Op = Instruction::SRem;
      break;
    case 6:
      Op = Instruction::URem;
      break;
    case 7:
      Op = Instruction::And;
      break;
    case 8:
      Op = Instruction::Or;
      break;
    case 9:
      Op = Instruction::Xor;
      break;
    }
    Value *L, *R;
    genLR(L, R, Budget, Width);
    Value *V = Builder->CreateBinOp(Op, L, R);
    if (!NoUB) {
      if ((Op == Instruction::Add || Op == Instruction::Sub ||
           Op == Instruction::Mul || Op == Instruction::Shl) &&
          Choose(2)) {
        BinaryOperator *B = cast<BinaryOperator>(V);
        B->setHasNoSignedWrap(true);
      }
      if ((Op == Instruction::Add || Op == Instruction::Sub ||
           Op == Instruction::Mul || Op == Instruction::Shl) &&
          Choose(2)) {
        BinaryOperator *B = cast<BinaryOperator>(V);
        B->setHasNoUnsignedWrap(true);
      }
      if ((Op == Instruction::UDiv || Op == Instruction::SDiv ||
           Op == Instruction::LShr || Op == Instruction::AShr) &&
          Choose(2)) {
        BinaryOperator *B = cast<BinaryOperator>(V);
        B->setIsExact(true);
      }
    }
    Vals.push_back(V);
    return V;
  }

  if (ConstOK && Choose(2)) {
    if (Verbose)
      errs() << "adding a const with width = " << Width
             << " and budget = " << Budget << "\n";
    if (OneConst) {
      return ConstantInt::get(*C, APInt(Width, 1));
    } else {
      int n = Choose((1 << Width) + 1);
      if (n == (1 << Width))
        return UndefValue::get(Type::getIntNTy(*C, Width));
      else
        return ConstantInt::get(*C, APInt(Width, n));
    }
  }

  if (Verbose)
    errs() << "using existing val with width = " << Width
           << " and budget = " << Budget << " and ArgOK = " << ArgOK << "\n";
  std::vector<Value *> Vs;
  for (auto &it : Vals)
    if (it->getType()->getPrimitiveSizeInBits() == Width)
      Vs.push_back(it);
  unsigned choices = Vs.size() + (ArgOK ? 1 : 0);
  if (choices == 0)
    exit(0);
  unsigned which = Choose(choices);
  if (which == Vs.size()) {
    Value *V = 0;
    for (auto it = F->arg_begin(); it != F->arg_end(); ++it) {
      if (UsedArgs.find(it) == UsedArgs.end() &&
          it->getType()->getPrimitiveSizeInBits() == Width) {
        UsedArgs.insert(it);
        V = it;
        Vals.push_back(V);
        break;
      }
    }
    ensure(V);
    return V;
  } else {
    return Vs.at(which);
  }
}

//.........这里部分代码省略.........
      if (I.getOpcode() == Instruction::LShr &&
          ShiftOp->getOpcode() == Instruction::Shl) {
        APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
        return BinaryOperator::CreateAnd(X,
                                        ConstantInt::get(I.getContext(), Mask));
      }
    } else if (ShiftAmt1 < ShiftAmt2) {
      uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;

      // (X >>?,exact C1) << C2 --> X << (C2-C1)
      // The inexact version is deferred to DAGCombine so we don't hide shl
      // behind a bit mask.
      if (I.getOpcode() == Instruction::Shl &&
          ShiftOp->getOpcode() != Instruction::Shl &&
          ShiftOp->isExact()) {
        assert(ShiftOp->getOpcode() == Instruction::LShr ||
               ShiftOp->getOpcode() == Instruction::AShr);
        ConstantInt *ShiftDiffCst = ConstantInt::get(Ty, ShiftDiff);
        BinaryOperator *NewShl = BinaryOperator::Create(Instruction::Shl,
                                                        X, ShiftDiffCst);
        NewShl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
        NewShl->setHasNoSignedWrap(I.hasNoSignedWrap());
        return NewShl;
      }

      // (X << C1) >>u C2  --> X >>u (C2-C1) & (-1 >> C2)
      if (I.getOpcode() == Instruction::LShr &&
          ShiftOp->getOpcode() == Instruction::Shl) {
        ConstantInt *ShiftDiffCst = ConstantInt::get(Ty, ShiftDiff);
        // (X <<nuw C1) >>u C2 --> X >>u (C2-C1)
        if (ShiftOp->hasNoUnsignedWrap()) {
          BinaryOperator *NewLShr = BinaryOperator::Create(Instruction::LShr,
                                                           X, ShiftDiffCst);
          NewLShr->setIsExact(I.isExact());
          return NewLShr;
        }
        Value *Shift = Builder->CreateLShr(X, ShiftDiffCst);

        APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
        return BinaryOperator::CreateAnd(Shift,
                                         ConstantInt::get(I.getContext(),Mask));
      }

      // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in. However,
      // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
      if (I.getOpcode() == Instruction::AShr &&
          ShiftOp->getOpcode() == Instruction::Shl) {
        if (ShiftOp->hasNoSignedWrap()) {
          // (X <<nsw C1) >>s C2 --> X >>s (C2-C1)
          ConstantInt *ShiftDiffCst = ConstantInt::get(Ty, ShiftDiff);
          BinaryOperator *NewAShr = BinaryOperator::Create(Instruction::AShr,
                                                           X, ShiftDiffCst);
          NewAShr->setIsExact(I.isExact());
          return NewAShr;
        }
      }
    } else {
      assert(ShiftAmt2 < ShiftAmt1);
      uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;

      // (X >>?exact C1) << C2 --> X >>?exact (C1-C2)
      // The inexact version is deferred to DAGCombine so we don't hide shl
      // behind a bit mask.
      if (I.getOpcode() == Instruction::Shl &&
          ShiftOp->getOpcode() != Instruction::Shl &&
          ShiftOp->isExact()) {

/// GetShiftedValue - When CanEvaluateShifted returned true for an expression,
/// this value inserts the new computation that produces the shifted value.
static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
                              InstCombiner &IC) {
  // We can always evaluate constants shifted.
  if (Constant *C = dyn_cast<Constant>(V)) {
    if (isLeftShift)
      V = IC.Builder->CreateShl(C, NumBits);
    else
      V = IC.Builder->CreateLShr(C, NumBits);
    // If we got a constantexpr back, try to simplify it with TD info.
    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
      V = ConstantFoldConstantExpression(CE, IC.getDataLayout(),
                                         IC.getTargetLibraryInfo());
    return V;
  }

  Instruction *I = cast<Instruction>(V);
  IC.Worklist.Add(I);

  switch (I->getOpcode()) {
  default: llvm_unreachable("Inconsistency with CanEvaluateShifted");
  case Instruction::And:
  case Instruction::Or:
  case Instruction::Xor:
    // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
    I->setOperand(0, GetShiftedValue(I->getOperand(0), NumBits,isLeftShift,IC));
    I->setOperand(1, GetShiftedValue(I->getOperand(1), NumBits,isLeftShift,IC));
    return I;

  case Instruction::Shl: {
    BinaryOperator *BO = cast<BinaryOperator>(I);
    unsigned TypeWidth = BO->getType()->getScalarSizeInBits();

    // We only accept shifts-by-a-constant in CanEvaluateShifted.
    ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));

    // We can always fold shl(c1)+shl(c2) -> shl(c1+c2).
    if (isLeftShift) {
      // If this is oversized composite shift, then unsigned shifts get 0.
      unsigned NewShAmt = NumBits+CI->getZExtValue();
      if (NewShAmt >= TypeWidth)
        return Constant::getNullValue(I->getType());

      BO->setOperand(1, ConstantInt::get(BO->getType(), NewShAmt));
      BO->setHasNoUnsignedWrap(false);
      BO->setHasNoSignedWrap(false);
      return I;
    }

    // We turn shl(c)+lshr(c) -> and(c2) if the input doesn't already have
    // zeros.
    if (CI->getValue() == NumBits) {
      APInt Mask(APInt::getLowBitsSet(TypeWidth, TypeWidth - NumBits));
      V = IC.Builder->CreateAnd(BO->getOperand(0),
                                ConstantInt::get(BO->getContext(), Mask));
      if (Instruction *VI = dyn_cast<Instruction>(V)) {
        VI->moveBefore(BO);
        VI->takeName(BO);
      }
      return V;
    }

    // We turn shl(c1)+shr(c2) -> shl(c3)+and(c4), but only when we know that
    // the and won't be needed.
    assert(CI->getZExtValue() > NumBits);
    BO->setOperand(1, ConstantInt::get(BO->getType(),
                                       CI->getZExtValue() - NumBits));
    BO->setHasNoUnsignedWrap(false);
    BO->setHasNoSignedWrap(false);
    return BO;
  }
  case Instruction::LShr: {
    BinaryOperator *BO = cast<BinaryOperator>(I);
    unsigned TypeWidth = BO->getType()->getScalarSizeInBits();
    // We only accept shifts-by-a-constant in CanEvaluateShifted.
    ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));

    // We can always fold lshr(c1)+lshr(c2) -> lshr(c1+c2).
    if (!isLeftShift) {
      // If this is oversized composite shift, then unsigned shifts get 0.
      unsigned NewShAmt = NumBits+CI->getZExtValue();
      if (NewShAmt >= TypeWidth)
        return Constant::getNullValue(BO->getType());

      BO->setOperand(1, ConstantInt::get(BO->getType(), NewShAmt));
      BO->setIsExact(false);
      return I;
    }

    // We turn lshr(c)+shl(c) -> and(c2) if the input doesn't already have
    // zeros.
    if (CI->getValue() == NumBits) {
      APInt Mask(APInt::getHighBitsSet(TypeWidth, TypeWidth - NumBits));
      V = IC.Builder->CreateAnd(I->getOperand(0),
                                ConstantInt::get(BO->getContext(), Mask));
      if (Instruction *VI = dyn_cast<Instruction>(V)) {
        VI->moveBefore(I);
        VI->takeName(I);
      }
//.........这里部分代码省略.........

/// This function implements the transforms common to both integer division
/// instructions (udiv and sdiv). It is called by the visitors to those integer
/// division instructions.
/// @brief Common integer divide transforms
Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);

  // The RHS is known non-zero.
  if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this)) {
    I.setOperand(1, V);
    return &I;
  }

  // Handle cases involving: [su]div X, (select Cond, Y, Z)
  // This does not apply for fdiv.
  if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
    return &I;

  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
    if (Instruction *LHS = dyn_cast<Instruction>(Op0)) {
      // (X / C1) / C2  -> X / (C1*C2)
      if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
        if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
          if (MultiplyOverflows(RHS, LHSRHS,
                                I.getOpcode() == Instruction::SDiv))
            return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
          return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
                                        ConstantExpr::getMul(RHS, LHSRHS));
        }

      Value *X;
      const APInt *C1, *C2;
      if (match(RHS, m_APInt(C2))) {
        bool IsSigned = I.getOpcode() == Instruction::SDiv;
        if ((IsSigned && match(LHS, m_NSWMul(m_Value(X), m_APInt(C1)))) ||
            (!IsSigned && match(LHS, m_NUWMul(m_Value(X), m_APInt(C1))))) {
          APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);

          // (X * C1) / C2 -> X / (C2 / C1) if C2 is a multiple of C1.
          if (IsMultiple(*C2, *C1, Quotient, IsSigned)) {
            BinaryOperator *BO = BinaryOperator::Create(
                I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient));
            BO->setIsExact(I.isExact());
            return BO;
          }

          // (X * C1) / C2 -> X * (C1 / C2) if C1 is a multiple of C2.
          if (IsMultiple(*C1, *C2, Quotient, IsSigned)) {
            BinaryOperator *BO = BinaryOperator::Create(
                Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient));
            BO->setHasNoUnsignedWrap(
                !IsSigned &&
                cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap());
            BO->setHasNoSignedWrap(
                cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap());
            return BO;
          }
        }

        if ((IsSigned && match(LHS, m_NSWShl(m_Value(X), m_APInt(C1)))) ||
            (!IsSigned && match(LHS, m_NUWShl(m_Value(X), m_APInt(C1))))) {
          APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned);
          APInt C1Shifted = APInt::getOneBitSet(
              C1->getBitWidth(), static_cast<unsigned>(C1->getLimitedValue()));

          // (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of C1.
          if (IsMultiple(*C2, C1Shifted, Quotient, IsSigned)) {
            BinaryOperator *BO = BinaryOperator::Create(
                I.getOpcode(), X, ConstantInt::get(X->getType(), Quotient));
            BO->setIsExact(I.isExact());
            return BO;
          }

          // (X << C1) / C2 -> X * (C2 >> C1) if C1 is a multiple of C2.
          if (IsMultiple(C1Shifted, *C2, Quotient, IsSigned)) {
            BinaryOperator *BO = BinaryOperator::Create(
                Instruction::Mul, X, ConstantInt::get(X->getType(), Quotient));
            BO->setHasNoUnsignedWrap(
                !IsSigned &&
                cast<OverflowingBinaryOperator>(LHS)->hasNoUnsignedWrap());
            BO->setHasNoSignedWrap(
                cast<OverflowingBinaryOperator>(LHS)->hasNoSignedWrap());
            return BO;
          }
        }
      }
    }

    if (!RHS->isZero()) { // avoid X udiv 0
      if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
        if (Instruction *R = FoldOpIntoSelect(I, SI))
          return R;
      if (isa<PHINode>(Op0))
        if (Instruction *NV = FoldOpIntoPhi(I))
          return NV;
    }
  }

  if (ConstantInt *One = dyn_cast<ConstantInt>(Op0)) {
    if (One->isOne() && !I.getType()->isIntegerTy(1)) {
//.........这里部分代码省略.........