text: //===- InstCombineCalls.cpp -----------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file implements the visitCall and visitInvoke functions.
  //
  //===----------------------------------------------------------------------===//
  
  #include "InstCombineInternal.h"
  #include "llvm/ADT/Statistic.h"
  #include "llvm/Analysis/InstructionSimplify.h"
  #include "llvm/Analysis/Loads.h"
  #include "llvm/Analysis/MemoryBuiltins.h"
  #include "llvm/IR/CallSite.h"
  #include "llvm/IR/Dominators.h"
  #include "llvm/IR/PatternMatch.h"
  #include "llvm/IR/Statepoint.h"
  #include "llvm/Transforms/Utils/BuildLibCalls.h"
  #include "llvm/Transforms/Utils/Local.h"
  #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
  using namespace llvm;
  using namespace PatternMatch;
  
  #define DEBUG_TYPE "instcombine"
  
  STATISTIC(NumSimplified, "Number of library calls simplified");
  
  /// Return the specified type promoted as it would be to pass though a va_arg
  /// area.
  static Type *getPromotedType(Type *Ty) {
    if (IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
      if (ITy->getBitWidth() < 32)
        return Type::getInt32Ty(Ty->getContext());
    }
    return Ty;
  }
  
  /// Given an aggregate type which ultimately holds a single scalar element,
  /// like {{{type}}} or [1 x type], return type.
  static Type *reduceToSingleValueType(Type *T) {
    while (!T->isSingleValueType()) {
      if (StructType *STy = dyn_cast<StructType>(T)) {
        if (STy->getNumElements() == 1)
          T = STy->getElementType(0);
        else
          break;
      } else if (ArrayType *ATy = dyn_cast<ArrayType>(T)) {
        if (ATy->getNumElements() == 1)
          T = ATy->getElementType();
        else
          break;
      } else
        break;
    }
  
    return T;
  }
  
  /// Return a constant boolean vector that has true elements in all positions
  /// where the input constant data vector has an element with the sign bit set.
  static Constant *getNegativeIsTrueBoolVec(ConstantDataVector *V) {
    SmallVector<Constant *, 32> BoolVec;
    IntegerType *BoolTy = Type::getInt1Ty(V->getContext());
    for (unsigned I = 0, E = V->getNumElements(); I != E; ++I) {
      Constant *Elt = V->getElementAsConstant(I);
      assert((isa<ConstantInt>(Elt) || isa<ConstantFP>(Elt)) &&
             "Unexpected constant data vector element type");
      bool Sign = V->getElementType()->isIntegerTy()
                      ? cast<ConstantInt>(Elt)->isNegative()
                      : cast<ConstantFP>(Elt)->isNegative();
      BoolVec.push_back(ConstantInt::get(BoolTy, Sign));
    }
    return ConstantVector::get(BoolVec);
  }
  
  Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
    unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), DL, MI, AC, DT);
    unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), DL, MI, AC, DT);
    unsigned MinAlign = std::min(DstAlign, SrcAlign);
    unsigned CopyAlign = MI->getAlignment();
  
    if (CopyAlign < MinAlign) {
      MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), MinAlign, false));
      return MI;
    }
  
    // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
    // load/store.
    ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getArgOperand(2));
    if (!MemOpLength) return nullptr;
  
    // Source and destination pointer types are always "i8*" for intrinsic.  See
    // if the size is something we can handle with a single primitive load/store.
    // A single load+store correctly handles overlapping memory in the memmove
    // case.
    uint64_t Size = MemOpLength->getLimitedValue();
    assert(Size && "0-sized memory transferring should be removed already.");
  
    if (Size > 8 || (Size&(Size-1)))
      return nullptr;  // If not 1/2/4/8 bytes, exit.
  
    // Use an integer load+store unless we can find something better.
    unsigned SrcAddrSp =
      cast<PointerType>(MI->getArgOperand(1)->getType())->getAddressSpace();
    unsigned DstAddrSp =
      cast<PointerType>(MI->getArgOperand(0)->getType())->getAddressSpace();
  
    IntegerType* IntType = IntegerType::get(MI->getContext(), Size<<3);
    Type *NewSrcPtrTy = PointerType::get(IntType, SrcAddrSp);
    Type *NewDstPtrTy = PointerType::get(IntType, DstAddrSp);
  
    // Memcpy forces the use of i8* for the source and destination.  That means
    // that if you're using memcpy to move one double around, you'll get a cast
    // from double* to i8*.  We'd much rather use a double load+store rather than
    // an i64 load+store, here because this improves the odds that the source or
    // dest address will be promotable.  See if we can find a better type than the
    // integer datatype.
    Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts();
    MDNode *CopyMD = nullptr;
    if (StrippedDest != MI->getArgOperand(0)) {
      Type *SrcETy = cast<PointerType>(StrippedDest->getType())
                                      ->getElementType();
      if (SrcETy->isSized() && DL.getTypeStoreSize(SrcETy) == Size) {
        // The SrcETy might be something like {{{double}}} or [1 x double].  Rip
        // down through these levels if so.
        SrcETy = reduceToSingleValueType(SrcETy);
  
        if (SrcETy->isSingleValueType()) {
          NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp);
          NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp);
  
          // If the memcpy has metadata describing the members, see if we can
          // get the TBAA tag describing our copy.
          if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa_struct)) {
            if (M->getNumOperands() == 3 && M->getOperand(0) &&
                mdconst::hasa<ConstantInt>(M->getOperand(0)) &&
                mdconst::extract<ConstantInt>(M->getOperand(0))->isNullValue() &&
                M->getOperand(1) &&
                mdconst::hasa<ConstantInt>(M->getOperand(1)) &&
                mdconst::extract<ConstantInt>(M->getOperand(1))->getValue() ==
                    Size &&
                M->getOperand(2) && isa<MDNode>(M->getOperand(2)))
              CopyMD = cast<MDNode>(M->getOperand(2));
          }
        }
      }
    }
  
    // If the memcpy/memmove provides better alignment info than we can
    // infer, use it.
    SrcAlign = std::max(SrcAlign, CopyAlign);
    DstAlign = std::max(DstAlign, CopyAlign);
  
    Value *Src = Builder->CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy);
    Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
    LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile());
    L->setAlignment(SrcAlign);
    if (CopyMD)
      L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
    StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile());
    S->setAlignment(DstAlign);
    if (CopyMD)
      S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
  
    // Set the size of the copy to 0, it will be deleted on the next iteration.
    MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType()));
    return MI;
  }
  
  Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
    unsigned Alignment = getKnownAlignment(MI->getDest(), DL, MI, AC, DT);
    if (MI->getAlignment() < Alignment) {
      MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
                                               Alignment, false));
      return MI;
    }
  
    // Extract the length and alignment and fill if they are constant.
    ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
    ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
    if (!LenC || !FillC || !FillC->getType()->isIntegerTy(8))
      return nullptr;
    uint64_t Len = LenC->getLimitedValue();
    Alignment = MI->getAlignment();
    assert(Len && "0-sized memory setting should be removed already.");
  
    // memset(s,c,n) -> store s, c (for n=1,2,4,8)
    if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
      Type *ITy = IntegerType::get(MI->getContext(), Len*8);  // n=1 -> i8.
  
      Value *Dest = MI->getDest();
      unsigned DstAddrSp = cast<PointerType>(Dest->getType())->getAddressSpace();
      Type *NewDstPtrTy = PointerType::get(ITy, DstAddrSp);
      Dest = Builder->CreateBitCast(Dest, NewDstPtrTy);
  
      // Alignment 0 is identity for alignment 1 for memset, but not store.
      if (Alignment == 0) Alignment = 1;
  
      // Extract the fill value and store.
      uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
      StoreInst *S = Builder->CreateStore(ConstantInt::get(ITy, Fill), Dest,
                                          MI->isVolatile());
      S->setAlignment(Alignment);
  
      // Set the size of the copy to 0, it will be deleted on the next iteration.
      MI->setLength(Constant::getNullValue(LenC->getType()));
      return MI;
    }
  
    return nullptr;
  }
  
  static Value *simplifyX86immShift(const IntrinsicInst &II,
                                    InstCombiner::BuilderTy &Builder) {
    bool LogicalShift = false;
    bool ShiftLeft = false;
  
    switch (II.getIntrinsicID()) {
    default:
      return nullptr;
    case Intrinsic::x86_sse2_psra_d:
    case Intrinsic::x86_sse2_psra_w:
    case Intrinsic::x86_sse2_psrai_d:
    case Intrinsic::x86_sse2_psrai_w:
    case Intrinsic::x86_avx2_psra_d:
    case Intrinsic::x86_avx2_psra_w:
    case Intrinsic::x86_avx2_psrai_d:
    case Intrinsic::x86_avx2_psrai_w:
      LogicalShift = false; ShiftLeft = false;
      break;
    case Intrinsic::x86_sse2_psrl_d:
    case Intrinsic::x86_sse2_psrl_q:
    case Intrinsic::x86_sse2_psrl_w:
    case Intrinsic::x86_sse2_psrli_d:
    case Intrinsic::x86_sse2_psrli_q:
    case Intrinsic::x86_sse2_psrli_w:
    case Intrinsic::x86_avx2_psrl_d:
    case Intrinsic::x86_avx2_psrl_q:
    case Intrinsic::x86_avx2_psrl_w:
    case Intrinsic::x86_avx2_psrli_d:
    case Intrinsic::x86_avx2_psrli_q:
    case Intrinsic::x86_avx2_psrli_w:
      LogicalShift = true; ShiftLeft = false;
      break;
    case Intrinsic::x86_sse2_psll_d:
    case Intrinsic::x86_sse2_psll_q:
    case Intrinsic::x86_sse2_psll_w:
    case Intrinsic::x86_sse2_pslli_d:
    case Intrinsic::x86_sse2_pslli_q:
    case Intrinsic::x86_sse2_pslli_w:
    case Intrinsic::x86_avx2_psll_d:
    case Intrinsic::x86_avx2_psll_q:
    case Intrinsic::x86_avx2_psll_w:
    case Intrinsic::x86_avx2_pslli_d:
    case Intrinsic::x86_avx2_pslli_q:
    case Intrinsic::x86_avx2_pslli_w:
      LogicalShift = true; ShiftLeft = true;
      break;
    }
    assert((LogicalShift || !ShiftLeft) && "Only logical shifts can shift left");
  
    // Simplify if count is constant.
    auto Arg1 = II.getArgOperand(1);
    auto CAZ = dyn_cast<ConstantAggregateZero>(Arg1);
    auto CDV = dyn_cast<ConstantDataVector>(Arg1);
    auto CInt = dyn_cast<ConstantInt>(Arg1);
    if (!CAZ && !CDV && !CInt)
      return nullptr;
  
    APInt Count(64, 0);
    if (CDV) {
      // SSE2/AVX2 uses all the first 64-bits of the 128-bit vector
      // operand to compute the shift amount.
      auto VT = cast<VectorType>(CDV->getType());
      unsigned BitWidth = VT->getElementType()->getPrimitiveSizeInBits();
      assert((64 % BitWidth) == 0 && "Unexpected packed shift size");
      unsigned NumSubElts = 64 / BitWidth;
  
      // Concatenate the sub-elements to create the 64-bit value.
      for (unsigned i = 0; i != NumSubElts; ++i) {
        unsigned SubEltIdx = (NumSubElts - 1) - i;
        auto SubElt = cast<ConstantInt>(CDV->getElementAsConstant(SubEltIdx));
        Count = Count.shl(BitWidth);
        Count |= SubElt->getValue().zextOrTrunc(64);
      }
    }
    else if (CInt)
      Count = CInt->getValue();
  
    auto Vec = II.getArgOperand(0);
    auto VT = cast<VectorType>(Vec->getType());
    auto SVT = VT->getElementType();
    unsigned VWidth = VT->getNumElements();
    unsigned BitWidth = SVT->getPrimitiveSizeInBits();
  
    // If shift-by-zero then just return the original value.
    if (Count == 0)
      return Vec;
  
    // Handle cases when Shift >= BitWidth.
    if (Count.uge(BitWidth)) {
      // If LogicalShift - just return zero.
      if (LogicalShift)
        return ConstantAggregateZero::get(VT);
  
      // If ArithmeticShift - clamp Shift to (BitWidth - 1).
      Count = APInt(64, BitWidth - 1);
    }
  
    // Get a constant vector of the same type as the first operand.
    auto ShiftAmt = ConstantInt::get(SVT, Count.zextOrTrunc(BitWidth));
    auto ShiftVec = Builder.CreateVectorSplat(VWidth, ShiftAmt);
  
    if (ShiftLeft)
      return Builder.CreateShl(Vec, ShiftVec);
  
    if (LogicalShift)
      return Builder.CreateLShr(Vec, ShiftVec);
  
    return Builder.CreateAShr(Vec, ShiftVec);
  }
  
  static Value *simplifyX86extend(const IntrinsicInst &II,
                                  InstCombiner::BuilderTy &Builder,
                                  bool SignExtend) {
    VectorType *SrcTy = cast<VectorType>(II.getArgOperand(0)->getType());
    VectorType *DstTy = cast<VectorType>(II.getType());
    unsigned NumDstElts = DstTy->getNumElements();
  
    // Extract a subvector of the first NumDstElts lanes and sign/zero extend.
    SmallVector<int, 8> ShuffleMask;
    for (int i = 0; i != (int)NumDstElts; ++i)
      ShuffleMask.push_back(i);
  
    Value *SV = Builder.CreateShuffleVector(II.getArgOperand(0),
                                            UndefValue::get(SrcTy), ShuffleMask);
    return SignExtend ? Builder.CreateSExt(SV, DstTy)
                      : Builder.CreateZExt(SV, DstTy);
  }
  
  static Value *simplifyX86insertps(const IntrinsicInst &II,
                                    InstCombiner::BuilderTy &Builder) {
    auto *CInt = dyn_cast<ConstantInt>(II.getArgOperand(2));
    if (!CInt)
      return nullptr;
  
    VectorType *VecTy = cast<VectorType>(II.getType());
    assert(VecTy->getNumElements() == 4 && "insertps with wrong vector type");
  
    // The immediate permute control byte looks like this:
    //    [3:0] - zero mask for each 32-bit lane
    //    [5:4] - select one 32-bit destination lane
    //    [7:6] - select one 32-bit source lane
  
    uint8_t Imm = CInt->getZExtValue();
    uint8_t ZMask = Imm & 0xf;
    uint8_t DestLane = (Imm >> 4) & 0x3;
    uint8_t SourceLane = (Imm >> 6) & 0x3;
  
    ConstantAggregateZero *ZeroVector = ConstantAggregateZero::get(VecTy);
  
    // If all zero mask bits are set, this was just a weird way to
    // generate a zero vector.
    if (ZMask == 0xf)
      return ZeroVector;
  
    // Initialize by passing all of the first source bits through.
    int ShuffleMask[4] = { 0, 1, 2, 3 };
  
    // We may replace the second operand with the zero vector.
    Value *V1 = II.getArgOperand(1);
  
    if (ZMask) {
      // If the zero mask is being used with a single input or the zero mask
      // overrides the destination lane, this is a shuffle with the zero vector.
      if ((II.getArgOperand(0) == II.getArgOperand(1)) ||
          (ZMask & (1 << DestLane))) {
        V1 = ZeroVector;
        // We may still move 32-bits of the first source vector from one lane
        // to another.
        ShuffleMask[DestLane] = SourceLane;
        // The zero mask may override the previous insert operation.
        for (unsigned i = 0; i < 4; ++i)
          if ((ZMask >> i) & 0x1)
            ShuffleMask[i] = i + 4;
      } else {
        // TODO: Model this case as 2 shuffles or a 'logical and' plus shuffle?
        return nullptr;
      }
    } else {
      // Replace the selected destination lane with the selected source lane.
      ShuffleMask[DestLane] = SourceLane + 4;
    }
  
    return Builder.CreateShuffleVector(II.getArgOperand(0), V1, ShuffleMask);
  }
  
  /// Attempt to simplify SSE4A EXTRQ/EXTRQI instructions using constant folding
  /// or conversion to a shuffle vector.
  static Value *simplifyX86extrq(IntrinsicInst &II, Value *Op0,
                                 ConstantInt *CILength, ConstantInt *CIIndex,
                                 InstCombiner::BuilderTy &Builder) {
    auto LowConstantHighUndef = [&](uint64_t Val) {
      Type *IntTy64 = Type::getInt64Ty(II.getContext());
      Constant *Args[] = {ConstantInt::get(IntTy64, Val),
                          UndefValue::get(IntTy64)};
      return ConstantVector::get(Args);
    };
  
    // See if we're dealing with constant values.
    Constant *C0 = dyn_cast<Constant>(Op0);
    ConstantInt *CI0 =
        C0 ? dyn_cast<ConstantInt>(C0->getAggregateElement((unsigned)0))
           : nullptr;
  
    // Attempt to constant fold.
    if (CILength && CIIndex) {
      // From AMD documentation: "The bit index and field length are each six
      // bits in length other bits of the field are ignored."
      APInt APIndex = CIIndex->getValue().zextOrTrunc(6);
      APInt APLength = CILength->getValue().zextOrTrunc(6);
  
      unsigned Index = APIndex.getZExtValue();
  
      // From AMD documentation: "a value of zero in the field length is
      // defined as length of 64".
      unsigned Length = APLength == 0 ? 64 : APLength.getZExtValue();
  
      // From AMD documentation: "If the sum of the bit index + length field
      // is greater than 64, the results are undefined".
      unsigned End = Index + Length;
  
      // Note that both field index and field length are 8-bit quantities.
      // Since variables 'Index' and 'Length' are unsigned values
      // obtained from zero-extending field index and field length
      // respectively, their sum should never wrap around.
      if (End > 64)
        return UndefValue::get(II.getType());
  
      // If we are inserting whole bytes, we can convert this to a shuffle.
      // Lowering can recognize EXTRQI shuffle masks.
      if ((Length % 8) == 0 && (Index % 8) == 0) {
        // Convert bit indices to byte indices.
        Length /= 8;
        Index /= 8;
  
        Type *IntTy8 = Type::getInt8Ty(II.getContext());
        Type *IntTy32 = Type::getInt32Ty(II.getContext());
        VectorType *ShufTy = VectorType::get(IntTy8, 16);
  
        SmallVector<Constant *, 16> ShuffleMask;
        for (int i = 0; i != (int)Length; ++i)
          ShuffleMask.push_back(
              Constant::getIntegerValue(IntTy32, APInt(32, i + Index)));
        for (int i = Length; i != 8; ++i)
          ShuffleMask.push_back(
              Constant::getIntegerValue(IntTy32, APInt(32, i + 16)));
        for (int i = 8; i != 16; ++i)
          ShuffleMask.push_back(UndefValue::get(IntTy32));
  
        Value *SV = Builder.CreateShuffleVector(
            Builder.CreateBitCast(Op0, ShufTy),
            ConstantAggregateZero::get(ShufTy), ConstantVector::get(ShuffleMask));
        return Builder.CreateBitCast(SV, II.getType());
      }
  
      // Constant Fold - shift Index'th bit to lowest position and mask off
      // Length bits.
      if (CI0) {
        APInt Elt = CI0->getValue();
        Elt = Elt.lshr(Index).zextOrTrunc(Length);
        return LowConstantHighUndef(Elt.getZExtValue());
      }
  
      // If we were an EXTRQ call, we'll save registers if we convert to EXTRQI.
      if (II.getIntrinsicID() == Intrinsic::x86_sse4a_extrq) {
        Value *Args[] = {Op0, CILength, CIIndex};
        Module *M = II.getModule();
        Value *F = Intrinsic::getDeclaration(M, Intrinsic::x86_sse4a_extrqi);
        return Builder.CreateCall(F, Args);
      }
    }
  
    // Constant Fold - extraction from zero is always {zero, undef}.
    if (CI0 && CI0->equalsInt(0))
      return LowConstantHighUndef(0);
  
    return nullptr;
  }
  
  /// Attempt to simplify SSE4A INSERTQ/INSERTQI instructions using constant
  /// folding or conversion to a shuffle vector.
  static Value *simplifyX86insertq(IntrinsicInst &II, Value *Op0, Value *Op1,
                                   APInt APLength, APInt APIndex,
                                   InstCombiner::BuilderTy &Builder) {
  
    // From AMD documentation: "The bit index and field length are each six bits
    // in length other bits of the field are ignored."
    APIndex = APIndex.zextOrTrunc(6);
    APLength = APLength.zextOrTrunc(6);
  
    // Attempt to constant fold.
    unsigned Index = APIndex.getZExtValue();
  
    // From AMD documentation: "a value of zero in the field length is
    // defined as length of 64".
    unsigned Length = APLength == 0 ? 64 : APLength.getZExtValue();
  
    // From AMD documentation: "If the sum of the bit index + length field
    // is greater than 64, the results are undefined".
    unsigned End = Index + Length;
  
    // Note that both field index and field length are 8-bit quantities.
    // Since variables 'Index' and 'Length' are unsigned values
    // obtained from zero-extending field index and field length
    // respectively, their sum should never wrap around.
    if (End > 64)
      return UndefValue::get(II.getType());
  
    // If we are inserting whole bytes, we can convert this to a shuffle.
    // Lowering can recognize INSERTQI shuffle masks.
    if ((Length % 8) == 0 && (Index % 8) == 0) {
      // Convert bit indices to byte indices.
      Length /= 8;
      Index /= 8;
  
      Type *IntTy8 = Type::getInt8Ty(II.getContext());
      Type *IntTy32 = Type::getInt32Ty(II.getContext());
      VectorType *ShufTy = VectorType::get(IntTy8, 16);
  
      SmallVector<Constant *, 16> ShuffleMask;
      for (int i = 0; i != (int)Index; ++i)
        ShuffleMask.push_back(Constant::getIntegerValue(IntTy32, APInt(32, i)));
      for (int i = 0; i != (int)Length; ++i)
        ShuffleMask.push_back(
            Constant::getIntegerValue(IntTy32, APInt(32, i + 16)));
      for (int i = Index + Length; i != 8; ++i)
        ShuffleMask.push_back(Constant::getIntegerValue(IntTy32, APInt(32, i)));
      for (int i = 8; i != 16; ++i)
        ShuffleMask.push_back(UndefValue::get(IntTy32));
  
      Value *SV = Builder.CreateShuffleVector(Builder.CreateBitCast(Op0, ShufTy),
                                              Builder.CreateBitCast(Op1, ShufTy),
                                              ConstantVector::get(ShuffleMask));
      return Builder.CreateBitCast(SV, II.getType());
    }
  
    // See if we're dealing with constant values.
    Constant *C0 = dyn_cast<Constant>(Op0);
    Constant *C1 = dyn_cast<Constant>(Op1);
    ConstantInt *CI00 =
        C0 ? dyn_cast<ConstantInt>(C0->getAggregateElement((unsigned)0))
           : nullptr;
    ConstantInt *CI10 =
        C1 ? dyn_cast<ConstantInt>(C1->getAggregateElement((unsigned)0))
           : nullptr;
  
    // Constant Fold - insert bottom Length bits starting at the Index'th bit.
    if (CI00 && CI10) {
      APInt V00 = CI00->getValue();
      APInt V10 = CI10->getValue();
      APInt Mask = APInt::getLowBitsSet(64, Length).shl(Index);
      V00 = V00 & ~Mask;
      V10 = V10.zextOrTrunc(Length).zextOrTrunc(64).shl(Index);
      APInt Val = V00 | V10;
      Type *IntTy64 = Type::getInt64Ty(II.getContext());
      Constant *Args[] = {ConstantInt::get(IntTy64, Val.getZExtValue()),
                          UndefValue::get(IntTy64)};
      return ConstantVector::get(Args);
    }
  
    // If we were an INSERTQ call, we'll save demanded elements if we convert to
    // INSERTQI.
    if (II.getIntrinsicID() == Intrinsic::x86_sse4a_insertq) {
      Type *IntTy8 = Type::getInt8Ty(II.getContext());
      Constant *CILength = ConstantInt::get(IntTy8, Length, false);
      Constant *CIIndex = ConstantInt::get(IntTy8, Index, false);
  
      Value *Args[] = {Op0, Op1, CILength, CIIndex};
      Module *M = II.getModule();
      Value *F = Intrinsic::getDeclaration(M, Intrinsic::x86_sse4a_insertqi);
      return Builder.CreateCall(F, Args);
    }
  
    return nullptr;
  }
  
  /// Attempt to convert pshufb* to shufflevector if the mask is constant.
  static Value *simplifyX86pshufb(const IntrinsicInst &II,
                                  InstCombiner::BuilderTy &Builder) {
    Constant *V = dyn_cast<Constant>(II.getArgOperand(1));
    if (!V)
      return nullptr;
  
    auto *VecTy = cast<VectorType>(II.getType());
    auto *MaskEltTy = Type::getInt32Ty(II.getContext());
    unsigned NumElts = VecTy->getNumElements();
    assert((NumElts == 16 || NumElts == 32) &&
           "Unexpected number of elements in shuffle mask!");
  
    // Construct a shuffle mask from constant integers or UNDEFs.
    Constant *Indexes[32] = {NULL};
  
    // Each byte in the shuffle control mask forms an index to permute the
    // corresponding byte in the destination operand.
    for (unsigned I = 0; I < NumElts; ++I) {
      Constant *COp = V->getAggregateElement(I);
      if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
        return nullptr;
  
      if (isa<UndefValue>(COp)) {
        Indexes[I] = UndefValue::get(MaskEltTy);
        continue;
      }
  
      int8_t Index = cast<ConstantInt>(COp)->getValue().getZExtValue();
  
      // If the most significant bit (bit[7]) of each byte of the shuffle
      // control mask is set, then zero is written in the result byte.
      // The zero vector is in the right-hand side of the resulting
      // shufflevector.
  
      // The value of each index for the high 128-bit lane is the least
      // significant 4 bits of the respective shuffle control byte.
      Index = ((Index < 0) ? NumElts : Index & 0x0F) + (I & 0xF0);
      Indexes[I] = ConstantInt::get(MaskEltTy, Index);
    }
  
    auto ShuffleMask = ConstantVector::get(makeArrayRef(Indexes, NumElts));
    auto V1 = II.getArgOperand(0);
    auto V2 = Constant::getNullValue(VecTy);
    return Builder.CreateShuffleVector(V1, V2, ShuffleMask);
  }
  
  /// Attempt to convert vpermilvar* to shufflevector if the mask is constant.
  static Value *simplifyX86vpermilvar(const IntrinsicInst &II,
                                      InstCombiner::BuilderTy &Builder) {
    Constant *V = dyn_cast<Constant>(II.getArgOperand(1));
    if (!V)
      return nullptr;
  
    auto *MaskEltTy = Type::getInt32Ty(II.getContext());
    unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
    assert(NumElts == 8 || NumElts == 4 || NumElts == 2);
  
    // Construct a shuffle mask from constant integers or UNDEFs.
    Constant *Indexes[8] = {NULL};
  
    // The intrinsics only read one or two bits, clear the rest.
    for (unsigned I = 0; I < NumElts; ++I) {
      Constant *COp = V->getAggregateElement(I);
      if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
        return nullptr;
  
      if (isa<UndefValue>(COp)) {
        Indexes[I] = UndefValue::get(MaskEltTy);
        continue;
      }
  
      APInt Index = cast<ConstantInt>(COp)->getValue();
      Index = Index.zextOrTrunc(32).getLoBits(2);
  
      // The PD variants uses bit 1 to select per-lane element index, so
      // shift down to convert to generic shuffle mask index.
      if (II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd ||
          II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd_256)
        Index = Index.lshr(1);
  
      // The _256 variants are a bit trickier since the mask bits always index
      // into the corresponding 128 half. In order to convert to a generic
      // shuffle, we have to make that explicit.
      if ((II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_ps_256 ||
           II.getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd_256) &&
          ((NumElts / 2) <= I)) {
        Index += APInt(32, NumElts / 2);
      }
  
      Indexes[I] = ConstantInt::get(MaskEltTy, Index);
    }
  
    auto ShuffleMask = ConstantVector::get(makeArrayRef(Indexes, NumElts));
    auto V1 = II.getArgOperand(0);
    auto V2 = UndefValue::get(V1->getType());
    return Builder.CreateShuffleVector(V1, V2, ShuffleMask);
  }
  
  /// Attempt to convert vpermd/vpermps to shufflevector if the mask is constant.
  static Value *simplifyX86vpermv(const IntrinsicInst &II,
                                  InstCombiner::BuilderTy &Builder) {
    auto *V = dyn_cast<Constant>(II.getArgOperand(1));
    if (!V)
      return nullptr;
  
    auto *VecTy = cast<VectorType>(II.getType());
    auto *MaskEltTy = Type::getInt32Ty(II.getContext());
    unsigned Size = VecTy->getNumElements();
    assert(Size == 8 && "Unexpected shuffle mask size");
  
    // Construct a shuffle mask from constant integers or UNDEFs.
    Constant *Indexes[8] = {NULL};
  
    for (unsigned I = 0; I < Size; ++I) {
      Constant *COp = V->getAggregateElement(I);
      if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
        return nullptr;
  
      if (isa<UndefValue>(COp)) {
        Indexes[I] = UndefValue::get(MaskEltTy);
        continue;
      }
  
      APInt Index = cast<ConstantInt>(COp)->getValue();
      Index = Index.zextOrTrunc(32).getLoBits(3);
      Indexes[I] = ConstantInt::get(MaskEltTy, Index);
    }
  
    auto ShuffleMask = ConstantVector::get(makeArrayRef(Indexes, Size));
    auto V1 = II.getArgOperand(0);
    auto V2 = UndefValue::get(VecTy);
    return Builder.CreateShuffleVector(V1, V2, ShuffleMask);
  }
  
  /// The shuffle mask for a perm2*128 selects any two halves of two 256-bit
  /// source vectors, unless a zero bit is set. If a zero bit is set,
  /// then ignore that half of the mask and clear that half of the vector.
  static Value *simplifyX86vperm2(const IntrinsicInst &II,
                                  InstCombiner::BuilderTy &Builder) {
    auto *CInt = dyn_cast<ConstantInt>(II.getArgOperand(2));
    if (!CInt)
      return nullptr;
  
    VectorType *VecTy = cast<VectorType>(II.getType());
    ConstantAggregateZero *ZeroVector = ConstantAggregateZero::get(VecTy);
  
    // The immediate permute control byte looks like this:
    //    [1:0] - select 128 bits from sources for low half of destination
    //    [2]   - ignore
    //    [3]   - zero low half of destination
    //    [5:4] - select 128 bits from sources for high half of destination
    //    [6]   - ignore
    //    [7]   - zero high half of destination
  
    uint8_t Imm = CInt->getZExtValue();
  
    bool LowHalfZero = Imm & 0x08;
    bool HighHalfZero = Imm & 0x80;
  
    // If both zero mask bits are set, this was just a weird way to
    // generate a zero vector.
    if (LowHalfZero && HighHalfZero)
      return ZeroVector;
  
    // If 0 or 1 zero mask bits are set, this is a simple shuffle.
    unsigned NumElts = VecTy->getNumElements();
    unsigned HalfSize = NumElts / 2;
    SmallVector<int, 8> ShuffleMask(NumElts);
  
    // The high bit of the selection field chooses the 1st or 2nd operand.
    bool LowInputSelect = Imm & 0x02;
    bool HighInputSelect = Imm & 0x20;
  
    // The low bit of the selection field chooses the low or high half
    // of the selected operand.
    bool LowHalfSelect = Imm & 0x01;
    bool HighHalfSelect = Imm & 0x10;
  
    // Determine which operand(s) are actually in use for this instruction.
    Value *V0 = LowInputSelect ? II.getArgOperand(1) : II.getArgOperand(0);
    Value *V1 = HighInputSelect ? II.getArgOperand(1) : II.getArgOperand(0);
  
    // If needed, replace operands based on zero mask.
    V0 = LowHalfZero ? ZeroVector : V0;
    V1 = HighHalfZero ? ZeroVector : V1;
  
    // Permute low half of result.
    unsigned StartIndex = LowHalfSelect ? HalfSize : 0;
    for (unsigned i = 0; i < HalfSize; ++i)
      ShuffleMask[i] = StartIndex + i;
  
    // Permute high half of result.
    StartIndex = HighHalfSelect ? HalfSize : 0;
    StartIndex += NumElts;
    for (unsigned i = 0; i < HalfSize; ++i)
      ShuffleMask[i + HalfSize] = StartIndex + i;
  
    return Builder.CreateShuffleVector(V0, V1, ShuffleMask);
  }
  
  /// Decode XOP integer vector comparison intrinsics.
  static Value *simplifyX86vpcom(const IntrinsicInst &II,
                                 InstCombiner::BuilderTy &Builder,
                                 bool IsSigned) {
    if (auto *CInt = dyn_cast<ConstantInt>(II.getArgOperand(2))) {
      uint64_t Imm = CInt->getZExtValue() & 0x7;
      VectorType *VecTy = cast<VectorType>(II.getType());
      CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
  
      switch (Imm) {
      case 0x0:
        Pred = IsSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
        break;
      case 0x1:
        Pred = IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
        break;
      case 0x2:
        Pred = IsSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
        break;
      case 0x3:
        Pred = IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
        break;
      case 0x4:
        Pred = ICmpInst::ICMP_EQ; break;
      case 0x5:
        Pred = ICmpInst::ICMP_NE; break;
      case 0x6:
        return ConstantInt::getSigned(VecTy, 0); // FALSE
      case 0x7:
        return ConstantInt::getSigned(VecTy, -1); // TRUE
      }
  
      if (Value *Cmp = Builder.CreateICmp(Pred, II.getArgOperand(0),
                                          II.getArgOperand(1)))
        return Builder.CreateSExtOrTrunc(Cmp, VecTy);
    }
    return nullptr;
  }
  
  static Value *simplifyMinnumMaxnum(const IntrinsicInst &II) {
    Value *Arg0 = II.getArgOperand(0);
    Value *Arg1 = II.getArgOperand(1);
  
    // fmin(x, x) -> x
    if (Arg0 == Arg1)
      return Arg0;
  
    const auto *C1 = dyn_cast<ConstantFP>(Arg1);
  
    // fmin(x, nan) -> x
    if (C1 && C1->isNaN())
      return Arg0;
  
    // This is the value because if undef were NaN, we would return the other
    // value and cannot return a NaN unless both operands are.
    //
    // fmin(undef, x) -> x
    if (isa<UndefValue>(Arg0))
      return Arg1;
  
    // fmin(x, undef) -> x
    if (isa<UndefValue>(Arg1))
      return Arg0;
  
    Value *X = nullptr;
    Value *Y = nullptr;
    if (II.getIntrinsicID() == Intrinsic::minnum) {
      // fmin(x, fmin(x, y)) -> fmin(x, y)
      // fmin(y, fmin(x, y)) -> fmin(x, y)
      if (match(Arg1, m_FMin(m_Value(X), m_Value(Y)))) {
        if (Arg0 == X || Arg0 == Y)
          return Arg1;
      }
  
      // fmin(fmin(x, y), x) -> fmin(x, y)
      // fmin(fmin(x, y), y) -> fmin(x, y)
      if (match(Arg0, m_FMin(m_Value(X), m_Value(Y)))) {
        if (Arg1 == X || Arg1 == Y)
          return Arg0;
      }
  
      // TODO: fmin(nnan x, inf) -> x
      // TODO: fmin(nnan ninf x, flt_max) -> x
      if (C1 && C1->isInfinity()) {
        // fmin(x, -inf) -> -inf
        if (C1->isNegative())
          return Arg1;
      }
    } else {
      assert(II.getIntrinsicID() == Intrinsic::maxnum);
      // fmax(x, fmax(x, y)) -> fmax(x, y)
      // fmax(y, fmax(x, y)) -> fmax(x, y)
      if (match(Arg1, m_FMax(m_Value(X), m_Value(Y)))) {
        if (Arg0 == X || Arg0 == Y)
          return Arg1;
      }
  
      // fmax(fmax(x, y), x) -> fmax(x, y)
      // fmax(fmax(x, y), y) -> fmax(x, y)
      if (match(Arg0, m_FMax(m_Value(X), m_Value(Y)))) {
        if (Arg1 == X || Arg1 == Y)
          return Arg0;
      }
  
      // TODO: fmax(nnan x, -inf) -> x
      // TODO: fmax(nnan ninf x, -flt_max) -> x
      if (C1 && C1->isInfinity()) {
        // fmax(x, inf) -> inf
        if (!C1->isNegative())
          return Arg1;
      }
    }
    return nullptr;
  }
  
  static Value *simplifyMaskedLoad(const IntrinsicInst &II,
                                   InstCombiner::BuilderTy &Builder) {
    auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(2));
    if (!ConstMask)
      return nullptr;
  
    // If the mask is all zeros, the "passthru" argument is the result.
    if (ConstMask->isNullValue())
      return II.getArgOperand(3);
  
    // If the mask is all ones, this is a plain vector load of the 1st argument.
    if (ConstMask->isAllOnesValue()) {
      Value *LoadPtr = II.getArgOperand(0);
      unsigned Alignment = cast<ConstantInt>(II.getArgOperand(1))->getZExtValue();
      return Builder.CreateAlignedLoad(LoadPtr, Alignment, "unmaskedload");
    }
  
    return nullptr;
  }
  
  static Instruction *simplifyMaskedStore(IntrinsicInst &II, InstCombiner &IC) {
    auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(3));
    if (!ConstMask)
      return nullptr;
  
    // If the mask is all zeros, this instruction does nothing.
    if (ConstMask->isNullValue())
      return IC.eraseInstFromFunction(II);
  
    // If the mask is all ones, this is a plain vector store of the 1st argument.
    if (ConstMask->isAllOnesValue()) {
      Value *StorePtr = II.getArgOperand(1);
      unsigned Alignment = cast<ConstantInt>(II.getArgOperand(2))->getZExtValue();
      return new StoreInst(II.getArgOperand(0), StorePtr, false, Alignment);
    }
  
    return nullptr;
  }
  
  static Instruction *simplifyMaskedGather(IntrinsicInst &II, InstCombiner &IC) {
    // If the mask is all zeros, return the "passthru" argument of the gather.
    auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(2));
    if (ConstMask && ConstMask->isNullValue())
      return IC.replaceInstUsesWith(II, II.getArgOperand(3));
  
    return nullptr;
  }
  
  static Instruction *simplifyMaskedScatter(IntrinsicInst &II, InstCombiner &IC) {
    // If the mask is all zeros, a scatter does nothing.
    auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(3));
    if (ConstMask && ConstMask->isNullValue())
      return IC.eraseInstFromFunction(II);
  
    return nullptr;
  }
  
  // TODO: If the x86 backend knew how to convert a bool vector mask back to an
  // XMM register mask efficiently, we could transform all x86 masked intrinsics
  // to LLVM masked intrinsics and remove the x86 masked intrinsic defs.
  static Instruction *simplifyX86MaskedLoad(IntrinsicInst &II, InstCombiner &IC) {
    Value *Ptr = II.getOperand(0);
    Value *Mask = II.getOperand(1);
    Constant *ZeroVec = Constant::getNullValue(II.getType());
  
    // Special case a zero mask since that's not a ConstantDataVector.
    // This masked load instruction creates a zero vector.
    if (isa<ConstantAggregateZero>(Mask))
      return IC.replaceInstUsesWith(II, ZeroVec);
  
    auto *ConstMask = dyn_cast<ConstantDataVector>(Mask);
    if (!ConstMask)
      return nullptr;
  
    // The mask is constant. Convert this x86 intrinsic to the LLVM instrinsic
    // to allow target-independent optimizations.
  
    // First, cast the x86 intrinsic scalar pointer to a vector pointer to match
    // the LLVM intrinsic definition for the pointer argument.
    unsigned AddrSpace = cast<PointerType>(Ptr->getType())->getAddressSpace();
    PointerType *VecPtrTy = PointerType::get(II.getType(), AddrSpace);
    Value *PtrCast = IC.Builder->CreateBitCast(Ptr, VecPtrTy, "castvec");
  
    // Second, convert the x86 XMM integer vector mask to a vector of bools based
    // on each element's most significant bit (the sign bit).
    Constant *BoolMask = getNegativeIsTrueBoolVec(ConstMask);
  
    // The pass-through vector for an x86 masked load is a zero vector.
    CallInst *NewMaskedLoad =
        IC.Builder->CreateMaskedLoad(PtrCast, 1, BoolMask, ZeroVec);
    return IC.replaceInstUsesWith(II, NewMaskedLoad);
  }
  
  // TODO: If the x86 backend knew how to convert a bool vector mask back to an
  // XMM register mask efficiently, we could transform all x86 masked intrinsics
  // to LLVM masked intrinsics and remove the x86 masked intrinsic defs.
  static bool simplifyX86MaskedStore(IntrinsicInst &II, InstCombiner &IC) {
    Value *Ptr = II.getOperand(0);
    Value *Mask = II.getOperand(1);
    Value *Vec = II.getOperand(2);
  
    // Special case a zero mask since that's not a ConstantDataVector:
    // this masked store instruction does nothing.
    if (isa<ConstantAggregateZero>(Mask)) {
      IC.eraseInstFromFunction(II);
      return true;
    }
  
    // The SSE2 version is too weird (eg, unaligned but non-temporal) to do
    // anything else at this level.
    if (II.getIntrinsicID() == Intrinsic::x86_sse2_maskmov_dqu)
      return false;
  
    auto *ConstMask = dyn_cast<ConstantDataVector>(Mask);
    if (!ConstMask)
      return false;
  
    // The mask is constant. Convert this x86 intrinsic to the LLVM instrinsic
    // to allow target-independent optimizations.
  
    // First, cast the x86 intrinsic scalar pointer to a vector pointer to match
    // the LLVM intrinsic definition for the pointer argument.
    unsigned AddrSpace = cast<PointerType>(Ptr->getType())->getAddressSpace();
    PointerType *VecPtrTy = PointerType::get(Vec->getType(), AddrSpace);
    Value *PtrCast = IC.Builder->CreateBitCast(Ptr, VecPtrTy, "castvec");
  
    // Second, convert the x86 XMM integer vector mask to a vector of bools based
    // on each element's most significant bit (the sign bit).
    Constant *BoolMask = getNegativeIsTrueBoolVec(ConstMask);
  
    IC.Builder->CreateMaskedStore(Vec, PtrCast, 1, BoolMask);
  
    // 'Replace uses' doesn't work for stores. Erase the original masked store.
    IC.eraseInstFromFunction(II);
    return true;
  }
  
  // Returns true iff the 2 intrinsics have the same operands, limiting the
  // comparison to the first NumOperands.
  static bool haveSameOperands(const IntrinsicInst &I, const IntrinsicInst &E,
                               unsigned NumOperands) {
    assert(I.getNumArgOperands() >= NumOperands && "Not enough operands");
    assert(E.getNumArgOperands() >= NumOperands && "Not enough operands");
    for (unsigned i = 0; i < NumOperands; i++)
      if (I.getArgOperand(i) != E.getArgOperand(i))
        return false;
    return true;
  }
  
  // Remove trivially empty start/end intrinsic ranges, i.e. a start
  // immediately followed by an end (ignoring debuginfo or other
  // start/end intrinsics in between). As this handles only the most trivial
  // cases, tracking the nesting level is not needed:
  //
  //   call @llvm.foo.start(i1 0) ; &I
  //   call @llvm.foo.start(i1 0)
  //   call @llvm.foo.end(i1 0) ; This one will not be skipped: it will be removed
  //   call @llvm.foo.end(i1 0)
  static bool removeTriviallyEmptyRange(IntrinsicInst &I, unsigned StartID,
                                        unsigned EndID, InstCombiner &IC) {
    assert(I.getIntrinsicID() == StartID &&
           "Start intrinsic does not have expected ID");
    BasicBlock::iterator BI(I), BE(I.getParent()->end());
    for (++BI; BI != BE; ++BI) {
      if (auto *E = dyn_cast<IntrinsicInst>(BI)) {
        if (isa<DbgInfoIntrinsic>(E) || E->getIntrinsicID() == StartID)
          continue;
        if (E->getIntrinsicID() == EndID &&
            haveSameOperands(I, *E, E->getNumArgOperands())) {
          IC.eraseInstFromFunction(*E);
          IC.eraseInstFromFunction(I);
          return true;
        }
      }
      break;
    }
  
    return false;
  }
  
  Instruction *InstCombiner::visitVAStartInst(VAStartInst &I) {
    removeTriviallyEmptyRange(I, Intrinsic::vastart, Intrinsic::vaend, *this);
    return nullptr;
  }
  
  Instruction *InstCombiner::visitVACopyInst(VACopyInst &I) {
    removeTriviallyEmptyRange(I, Intrinsic::vacopy, Intrinsic::vaend, *this);
    return nullptr;
  }
  
  /// CallInst simplification. This mostly only handles folding of intrinsic
  /// instructions. For normal calls, it allows visitCallSite to do the heavy
  /// lifting.
  Instruction *InstCombiner::visitCallInst(CallInst &CI) {
    auto Args = CI.arg_operands();
    if (Value *V = SimplifyCall(CI.getCalledValue(), Args.begin(), Args.end(), DL,
                                TLI, DT, AC))
      return replaceInstUsesWith(CI, V);
  
    if (isFreeCall(&CI, TLI))
      return visitFree(CI);
  
    // If the caller function is nounwind, mark the call as nounwind, even if the
    // callee isn't.
    if (CI.getParent()->getParent()->doesNotThrow() &&
        !CI.doesNotThrow()) {
      CI.setDoesNotThrow();
      return &CI;
    }
  
    IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
    if (!II) return visitCallSite(&CI);
  
    // Intrinsics cannot occur in an invoke, so handle them here instead of in
    // visitCallSite.
    if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
      bool Changed = false;
  
      // memmove/cpy/set of zero bytes is a noop.
      if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
        if (NumBytes->isNullValue())
          return eraseInstFromFunction(CI);
  
        if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
          if (CI->getZExtValue() == 1) {
            // Replace the instruction with just byte operations.  We would
            // transform other cases to loads/stores, but we don't know if
            // alignment is sufficient.
          }
      }
  
      // No other transformations apply to volatile transfers.
      if (MI->isVolatile())
        return nullptr;
  
      // If we have a memmove and the source operation is a constant global,
      // then the source and dest pointers can't alias, so we can change this
      // into a call to memcpy.
      if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
        if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
          if (GVSrc->isConstant()) {
            Module *M = CI.getModule();
            Intrinsic::ID MemCpyID = Intrinsic::memcpy;
            Type *Tys[3] = { CI.getArgOperand(0)->getType(),
                             CI.getArgOperand(1)->getType(),
                             CI.getArgOperand(2)->getType() };
            CI.setCalledFunction(Intrinsic::getDeclaration(M, MemCpyID, Tys));
            Changed = true;
          }
      }
  
      if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
        // memmove(x,x,size) -> noop.
        if (MTI->getSource() == MTI->getDest())
          return eraseInstFromFunction(CI);
      }
  
      // If we can determine a pointer alignment that is bigger than currently
      // set, update the alignment.
      if (isa<MemTransferInst>(MI)) {
        if (Instruction *I = SimplifyMemTransfer(MI))
          return I;
      } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
        if (Instruction *I = SimplifyMemSet(MSI))
          return I;
      }
  
      if (Changed) return II;
    }
  
    auto SimplifyDemandedVectorEltsLow = [this](Value *Op, unsigned Width,
                                                unsigned DemandedWidth) {
      APInt UndefElts(Width, 0);
      APInt DemandedElts = APInt::getLowBitsSet(Width, DemandedWidth);
      return SimplifyDemandedVectorElts(Op, DemandedElts, UndefElts);
    };
    auto SimplifyDemandedVectorEltsHigh = [this](Value *Op, unsigned Width,
                                                unsigned DemandedWidth) {
      APInt UndefElts(Width, 0);
      APInt DemandedElts = APInt::getHighBitsSet(Width, DemandedWidth);
      return SimplifyDemandedVectorElts(Op, DemandedElts, UndefElts);
    };
  
    switch (II->getIntrinsicID()) {
    default: break;
    case Intrinsic::objectsize: {
      uint64_t Size;
      if (getObjectSize(II->getArgOperand(0), Size, DL, TLI)) {
        APInt APSize(II->getType()->getIntegerBitWidth(), Size);
        // Equality check to be sure that `Size` can fit in a value of type
        // `II->getType()`
        if (APSize == Size)
          return replaceInstUsesWith(CI, ConstantInt::get(II->getType(), APSize));
      }
      return nullptr;
    }
    case Intrinsic::bswap: {
      Value *IIOperand = II->getArgOperand(0);
      Value *X = nullptr;
  
      // bswap(bswap(x)) -> x
      if (match(IIOperand, m_BSwap(m_Value(X))))
          return replaceInstUsesWith(CI, X);
  
      // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
      if (match(IIOperand, m_Trunc(m_BSwap(m_Value(X))))) {
        unsigned C = X->getType()->getPrimitiveSizeInBits() -
          IIOperand->getType()->getPrimitiveSizeInBits();
        Value *CV = ConstantInt::get(X->getType(), C);
        Value *V = Builder->CreateLShr(X, CV);
        return new TruncInst(V, IIOperand->getType());
      }
      break;
    }
  
    case Intrinsic::bitreverse: {
      Value *IIOperand = II->getArgOperand(0);
      Value *X = nullptr;
  
      // bitreverse(bitreverse(x)) -> x
      if (match(IIOperand, m_Intrinsic<Intrinsic::bitreverse>(m_Value(X))))
        return replaceInstUsesWith(CI, X);
      break;
    }
  
    case Intrinsic::masked_load:
      if (Value *SimplifiedMaskedOp = simplifyMaskedLoad(*II, *Builder))
        return replaceInstUsesWith(CI, SimplifiedMaskedOp);
      break;
    case Intrinsic::masked_store:
      return simplifyMaskedStore(*II, *this);
    case Intrinsic::masked_gather:
      return simplifyMaskedGather(*II, *this);
    case Intrinsic::masked_scatter:
      return simplifyMaskedScatter(*II, *this);
  
    case Intrinsic::powi:
      if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
        // powi(x, 0) -> 1.0
        if (Power->isZero())
          return replaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
        // powi(x, 1) -> x
        if (Power->isOne())
          return replaceInstUsesWith(CI, II->getArgOperand(0));
        // powi(x, -1) -> 1/x
        if (Power->isAllOnesValue())
          return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
                                            II->getArgOperand(0));
      }
      break;
    case Intrinsic::cttz: {
      // If all bits below the first known one are known zero,
      // this value is constant.
      IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
      // FIXME: Try to simplify vectors of integers.
      if (!IT) break;
      uint32_t BitWidth = IT->getBitWidth();
      APInt KnownZero(BitWidth, 0);
      APInt KnownOne(BitWidth, 0);
      computeKnownBits(II->getArgOperand(0), KnownZero, KnownOne, 0, II);
      unsigned TrailingZeros = KnownOne.countTrailingZeros();
      APInt Mask(APInt::getLowBitsSet(BitWidth, TrailingZeros));
      if ((Mask & KnownZero) == Mask)
        return replaceInstUsesWith(CI, ConstantInt::get(IT,
                                   APInt(BitWidth, TrailingZeros)));
  
      }
      break;
    case Intrinsic::ctlz: {
      // If all bits above the first known one are known zero,
      // this value is constant.
      IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
      // FIXME: Try to simplify vectors of integers.
      if (!IT) break;
      uint32_t BitWidth = IT->getBitWidth();
      APInt KnownZero(BitWidth, 0);
      APInt KnownOne(BitWidth, 0);
      computeKnownBits(II->getArgOperand(0), KnownZero, KnownOne, 0, II);
      unsigned LeadingZeros = KnownOne.countLeadingZeros();
      APInt Mask(APInt::getHighBitsSet(BitWidth, LeadingZeros));
      if ((Mask & KnownZero) == Mask)
        return replaceInstUsesWith(CI, ConstantInt::get(IT,
                                   APInt(BitWidth, LeadingZeros)));
  
      }
      break;
  
    case Intrinsic::uadd_with_overflow:
    case Intrinsic::sadd_with_overflow:
    case Intrinsic::umul_with_overflow:
    case Intrinsic::smul_with_overflow:
      if (isa<Constant>(II->getArgOperand(0)) &&
          !isa<Constant>(II->getArgOperand(1))) {
        // Canonicalize constants into the RHS.
        Value *LHS = II->getArgOperand(0);
        II->setArgOperand(0, II->getArgOperand(1));
        II->setArgOperand(1, LHS);
        return II;
      }
      // fall through
  
    case Intrinsic::usub_with_overflow:
    case Intrinsic::ssub_with_overflow: {
      OverflowCheckFlavor OCF =
          IntrinsicIDToOverflowCheckFlavor(II->getIntrinsicID());
      assert(OCF != OCF_INVALID && "unexpected!");
  
      Value *OperationResult = nullptr;
      Constant *OverflowResult = nullptr;
      if (OptimizeOverflowCheck(OCF, II->getArgOperand(0), II->getArgOperand(1),
                                *II, OperationResult, OverflowResult))
        return CreateOverflowTuple(II, OperationResult, OverflowResult);
  
      break;
    }
  
    case Intrinsic::minnum:
    case Intrinsic::maxnum: {
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
      // Canonicalize constants to the RHS.
      if (isa<ConstantFP>(Arg0) && !isa<ConstantFP>(Arg1)) {
        II->setArgOperand(0, Arg1);
        II->setArgOperand(1, Arg0);
        return II;
      }
      if (Value *V = simplifyMinnumMaxnum(*II))
        return replaceInstUsesWith(*II, V);
      break;
    }
    case Intrinsic::ppc_altivec_lvx:
    case Intrinsic::ppc_altivec_lvxl:
      // Turn PPC lvx -> load if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, AC, DT) >=
          16) {
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
                                           PointerType::getUnqual(II->getType()));
        return new LoadInst(Ptr);
      }
      break;
    case Intrinsic::ppc_vsx_lxvw4x:
    case Intrinsic::ppc_vsx_lxvd2x: {
      // Turn PPC VSX loads into normal loads.
      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
                                          PointerType::getUnqual(II->getType()));
      return new LoadInst(Ptr, Twine(""), false, 1);
    }
    case Intrinsic::ppc_altivec_stvx:
    case Intrinsic::ppc_altivec_stvxl:
      // Turn stvx -> store if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, DL, II, AC, DT) >=
          16) {
        Type *OpPtrTy =
          PointerType::getUnqual(II->getArgOperand(0)->getType());
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
        return new StoreInst(II->getArgOperand(0), Ptr);
      }
      break;
    case Intrinsic::ppc_vsx_stxvw4x:
    case Intrinsic::ppc_vsx_stxvd2x: {
      // Turn PPC VSX stores into normal stores.
      Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(0)->getType());
      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
      return new StoreInst(II->getArgOperand(0), Ptr, false, 1);
    }
    case Intrinsic::ppc_qpx_qvlfs:
      // Turn PPC QPX qvlfs -> load if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, AC, DT) >=
          16) {
        Type *VTy = VectorType::get(Builder->getFloatTy(),
                                    II->getType()->getVectorNumElements());
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
                                           PointerType::getUnqual(VTy));
        Value *Load = Builder->CreateLoad(Ptr);
        return new FPExtInst(Load, II->getType());
      }
      break;
    case Intrinsic::ppc_qpx_qvlfd:
      // Turn PPC QPX qvlfd -> load if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(0), 32, DL, II, AC, DT) >=
          32) {
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
                                           PointerType::getUnqual(II->getType()));
        return new LoadInst(Ptr);
      }
      break;
    case Intrinsic::ppc_qpx_qvstfs:
      // Turn PPC QPX qvstfs -> store if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, DL, II, AC, DT) >=
          16) {
        Type *VTy = VectorType::get(Builder->getFloatTy(),
            II->getArgOperand(0)->getType()->getVectorNumElements());
        Value *TOp = Builder->CreateFPTrunc(II->getArgOperand(0), VTy);
        Type *OpPtrTy = PointerType::getUnqual(VTy);
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
        return new StoreInst(TOp, Ptr);
      }
      break;
    case Intrinsic::ppc_qpx_qvstfd:
      // Turn PPC QPX qvstfd -> store if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(1), 32, DL, II, AC, DT) >=
          32) {
        Type *OpPtrTy =
          PointerType::getUnqual(II->getArgOperand(0)->getType());
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
        return new StoreInst(II->getArgOperand(0), Ptr);
      }
      break;
  
    case Intrinsic::x86_sse_storeu_ps:
    case Intrinsic::x86_sse2_storeu_pd:
    case Intrinsic::x86_sse2_storeu_dq:
      // Turn X86 storeu -> store if the pointer is known aligned.
      if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, AC, DT) >=
          16) {
        Type *OpPtrTy =
          PointerType::getUnqual(II->getArgOperand(1)->getType());
        Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), OpPtrTy);
        return new StoreInst(II->getArgOperand(1), Ptr);
      }
      break;
  
    case Intrinsic::x86_vcvtph2ps_128:
    case Intrinsic::x86_vcvtph2ps_256: {
      auto Arg = II->getArgOperand(0);
      auto ArgType = cast<VectorType>(Arg->getType());
      auto RetType = cast<VectorType>(II->getType());
      unsigned ArgWidth = ArgType->getNumElements();
      unsigned RetWidth = RetType->getNumElements();
      assert(RetWidth <= ArgWidth && "Unexpected input/return vector widths");
      assert(ArgType->isIntOrIntVectorTy() &&
             ArgType->getScalarSizeInBits() == 16 &&
             "CVTPH2PS input type should be 16-bit integer vector");
      assert(RetType->getScalarType()->isFloatTy() &&
             "CVTPH2PS output type should be 32-bit float vector");
  
      // Constant folding: Convert to generic half to single conversion.
      if (isa<ConstantAggregateZero>(Arg))
        return replaceInstUsesWith(*II, ConstantAggregateZero::get(RetType));
  
      if (isa<ConstantDataVector>(Arg)) {
        auto VectorHalfAsShorts = Arg;
        if (RetWidth < ArgWidth) {
          SmallVector<int, 8> SubVecMask;
          for (unsigned i = 0; i != RetWidth; ++i)
            SubVecMask.push_back((int)i);
          VectorHalfAsShorts = Builder->CreateShuffleVector(
              Arg, UndefValue::get(ArgType), SubVecMask);
        }
  
        auto VectorHalfType =
            VectorType::get(Type::getHalfTy(II->getContext()), RetWidth);
        auto VectorHalfs =
            Builder->CreateBitCast(VectorHalfAsShorts, VectorHalfType);
        auto VectorFloats = Builder->CreateFPExt(VectorHalfs, RetType);
        return replaceInstUsesWith(*II, VectorFloats);
      }
  
      // We only use the lowest lanes of the argument.
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg, ArgWidth, RetWidth)) {
        II->setArgOperand(0, V);
        return II;
      }
      break;
    }
  
    case Intrinsic::x86_sse_cvtss2si:
    case Intrinsic::x86_sse_cvtss2si64:
    case Intrinsic::x86_sse_cvttss2si:
    case Intrinsic::x86_sse_cvttss2si64:
    case Intrinsic::x86_sse2_cvtsd2si:
    case Intrinsic::x86_sse2_cvtsd2si64:
    case Intrinsic::x86_sse2_cvttsd2si:
    case Intrinsic::x86_sse2_cvttsd2si64: {
      // These intrinsics only demand the 0th element of their input vectors. If
      // we can simplify the input based on that, do so now.
      Value *Arg = II->getArgOperand(0);
      unsigned VWidth = Arg->getType()->getVectorNumElements();
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg, VWidth, 1)) {
        II->setArgOperand(0, V);
        return II;
      }
      break;
    }
  
    case Intrinsic::x86_sse_comieq_ss:
    case Intrinsic::x86_sse_comige_ss:
    case Intrinsic::x86_sse_comigt_ss:
    case Intrinsic::x86_sse_comile_ss:
    case Intrinsic::x86_sse_comilt_ss:
    case Intrinsic::x86_sse_comineq_ss:
    case Intrinsic::x86_sse_ucomieq_ss:
    case Intrinsic::x86_sse_ucomige_ss:
    case Intrinsic::x86_sse_ucomigt_ss:
    case Intrinsic::x86_sse_ucomile_ss:
    case Intrinsic::x86_sse_ucomilt_ss:
    case Intrinsic::x86_sse_ucomineq_ss:
    case Intrinsic::x86_sse2_comieq_sd:
    case Intrinsic::x86_sse2_comige_sd:
    case Intrinsic::x86_sse2_comigt_sd:
    case Intrinsic::x86_sse2_comile_sd:
    case Intrinsic::x86_sse2_comilt_sd:
    case Intrinsic::x86_sse2_comineq_sd:
    case Intrinsic::x86_sse2_ucomieq_sd:
    case Intrinsic::x86_sse2_ucomige_sd:
    case Intrinsic::x86_sse2_ucomigt_sd:
    case Intrinsic::x86_sse2_ucomile_sd:
    case Intrinsic::x86_sse2_ucomilt_sd:
    case Intrinsic::x86_sse2_ucomineq_sd: {
      // These intrinsics only demand the 0th element of their input vectors. If
      // we can simplify the input based on that, do so now.
      bool MadeChange = false;
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
      unsigned VWidth = Arg0->getType()->getVectorNumElements();
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg0, VWidth, 1)) {
        II->setArgOperand(0, V);
        MadeChange = true;
      }
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg1, VWidth, 1)) {
        II->setArgOperand(1, V);
        MadeChange = true;
      }
      if (MadeChange)
        return II;
      break;
    }
  
    case Intrinsic::x86_sse_add_ss:
    case Intrinsic::x86_sse_sub_ss:
    case Intrinsic::x86_sse_mul_ss:
    case Intrinsic::x86_sse_div_ss:
    case Intrinsic::x86_sse_min_ss:
    case Intrinsic::x86_sse_max_ss:
    case Intrinsic::x86_sse_cmp_ss:
    case Intrinsic::x86_sse2_add_sd:
    case Intrinsic::x86_sse2_sub_sd:
    case Intrinsic::x86_sse2_mul_sd:
    case Intrinsic::x86_sse2_div_sd:
    case Intrinsic::x86_sse2_min_sd:
    case Intrinsic::x86_sse2_max_sd:
    case Intrinsic::x86_sse2_cmp_sd: {
      // These intrinsics only demand the lowest element of the second input
      // vector.
      Value *Arg1 = II->getArgOperand(1);
      unsigned VWidth = Arg1->getType()->getVectorNumElements();
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg1, VWidth, 1)) {
        II->setArgOperand(1, V);
        return II;
      }
      break;
    }
  
    case Intrinsic::x86_sse41_round_ss:
    case Intrinsic::x86_sse41_round_sd: {
      // These intrinsics demand the upper elements of the first input vector and
      // the lowest element of the second input vector.
      bool MadeChange = false;
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
      unsigned VWidth = Arg0->getType()->getVectorNumElements();
      if (Value *V = SimplifyDemandedVectorEltsHigh(Arg0, VWidth, VWidth - 1)) {
        II->setArgOperand(0, V);
        MadeChange = true;
      }
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg1, VWidth, 1)) {
        II->setArgOperand(1, V);
        MadeChange = true;
      }
      if (MadeChange)
        return II;
      break;
    }
  
    // Constant fold ashr( <A x Bi>, Ci ).
    // Constant fold lshr( <A x Bi>, Ci ).
    // Constant fold shl( <A x Bi>, Ci ).
    case Intrinsic::x86_sse2_psrai_d:
    case Intrinsic::x86_sse2_psrai_w:
    case Intrinsic::x86_avx2_psrai_d:
    case Intrinsic::x86_avx2_psrai_w:
    case Intrinsic::x86_sse2_psrli_d:
    case Intrinsic::x86_sse2_psrli_q:
    case Intrinsic::x86_sse2_psrli_w:
    case Intrinsic::x86_avx2_psrli_d:
    case Intrinsic::x86_avx2_psrli_q:
    case Intrinsic::x86_avx2_psrli_w:
    case Intrinsic::x86_sse2_pslli_d:
    case Intrinsic::x86_sse2_pslli_q:
    case Intrinsic::x86_sse2_pslli_w:
    case Intrinsic::x86_avx2_pslli_d:
    case Intrinsic::x86_avx2_pslli_q:
    case Intrinsic::x86_avx2_pslli_w:
      if (Value *V = simplifyX86immShift(*II, *Builder))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_sse2_psra_d:
    case Intrinsic::x86_sse2_psra_w:
    case Intrinsic::x86_avx2_psra_d:
    case Intrinsic::x86_avx2_psra_w:
    case Intrinsic::x86_sse2_psrl_d:
    case Intrinsic::x86_sse2_psrl_q:
    case Intrinsic::x86_sse2_psrl_w:
    case Intrinsic::x86_avx2_psrl_d:
    case Intrinsic::x86_avx2_psrl_q:
    case Intrinsic::x86_avx2_psrl_w:
    case Intrinsic::x86_sse2_psll_d:
    case Intrinsic::x86_sse2_psll_q:
    case Intrinsic::x86_sse2_psll_w:
    case Intrinsic::x86_avx2_psll_d:
    case Intrinsic::x86_avx2_psll_q:
    case Intrinsic::x86_avx2_psll_w: {
      if (Value *V = simplifyX86immShift(*II, *Builder))
        return replaceInstUsesWith(*II, V);
  
      // SSE2/AVX2 uses only the first 64-bits of the 128-bit vector
      // operand to compute the shift amount.
      Value *Arg1 = II->getArgOperand(1);
      assert(Arg1->getType()->getPrimitiveSizeInBits() == 128 &&
             "Unexpected packed shift size");
      unsigned VWidth = Arg1->getType()->getVectorNumElements();
  
      if (Value *V = SimplifyDemandedVectorEltsLow(Arg1, VWidth, VWidth / 2)) {
        II->setArgOperand(1, V);
        return II;
      }
      break;
    }
  
    case Intrinsic::x86_avx2_pmovsxbd:
    case Intrinsic::x86_avx2_pmovsxbq:
    case Intrinsic::x86_avx2_pmovsxbw:
    case Intrinsic::x86_avx2_pmovsxdq:
    case Intrinsic::x86_avx2_pmovsxwd:
    case Intrinsic::x86_avx2_pmovsxwq:
      if (Value *V = simplifyX86extend(*II, *Builder, true))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_sse41_pmovzxbd:
    case Intrinsic::x86_sse41_pmovzxbq:
    case Intrinsic::x86_sse41_pmovzxbw:
    case Intrinsic::x86_sse41_pmovzxdq:
    case Intrinsic::x86_sse41_pmovzxwd:
    case Intrinsic::x86_sse41_pmovzxwq:
    case Intrinsic::x86_avx2_pmovzxbd:
    case Intrinsic::x86_avx2_pmovzxbq:
    case Intrinsic::x86_avx2_pmovzxbw:
    case Intrinsic::x86_avx2_pmovzxdq:
    case Intrinsic::x86_avx2_pmovzxwd:
    case Intrinsic::x86_avx2_pmovzxwq:
      if (Value *V = simplifyX86extend(*II, *Builder, false))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_sse41_insertps:
      if (Value *V = simplifyX86insertps(*II, *Builder))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_sse4a_extrq: {
      Value *Op0 = II->getArgOperand(0);
      Value *Op1 = II->getArgOperand(1);
      unsigned VWidth0 = Op0->getType()->getVectorNumElements();
      unsigned VWidth1 = Op1->getType()->getVectorNumElements();
      assert(Op0->getType()->getPrimitiveSizeInBits() == 128 &&
             Op1->getType()->getPrimitiveSizeInBits() == 128 && VWidth0 == 2 &&
             VWidth1 == 16 && "Unexpected operand sizes");
  
      // See if we're dealing with constant values.
      Constant *C1 = dyn_cast<Constant>(Op1);
      ConstantInt *CILength =
          C1 ? dyn_cast<ConstantInt>(C1->getAggregateElement((unsigned)0))
             : nullptr;
      ConstantInt *CIIndex =
          C1 ? dyn_cast<ConstantInt>(C1->getAggregateElement((unsigned)1))
             : nullptr;
  
      // Attempt to simplify to a constant, shuffle vector or EXTRQI call.
      if (Value *V = simplifyX86extrq(*II, Op0, CILength, CIIndex, *Builder))
        return replaceInstUsesWith(*II, V);
  
      // EXTRQ only uses the lowest 64-bits of the first 128-bit vector
      // operands and the lowest 16-bits of the second.
      bool MadeChange = false;
      if (Value *V = SimplifyDemandedVectorEltsLow(Op0, VWidth0, 1)) {
        II->setArgOperand(0, V);
        MadeChange = true;
      }
      if (Value *V = SimplifyDemandedVectorEltsLow(Op1, VWidth1, 2)) {
        II->setArgOperand(1, V);
        MadeChange = true;
      }
      if (MadeChange)
        return II;
      break;
    }
  
    case Intrinsic::x86_sse4a_extrqi: {
      // EXTRQI: Extract Length bits starting from Index. Zero pad the remaining
      // bits of the lower 64-bits. The upper 64-bits are undefined.
      Value *Op0 = II->getArgOperand(0);
      unsigned VWidth = Op0->getType()->getVectorNumElements();
      assert(Op0->getType()->getPrimitiveSizeInBits() == 128 && VWidth == 2 &&
             "Unexpected operand size");
  
      // See if we're dealing with constant values.
      ConstantInt *CILength = dyn_cast<ConstantInt>(II->getArgOperand(1));
      ConstantInt *CIIndex = dyn_cast<ConstantInt>(II->getArgOperand(2));
  
      // Attempt to simplify to a constant or shuffle vector.
      if (Value *V = simplifyX86extrq(*II, Op0, CILength, CIIndex, *Builder))
        return replaceInstUsesWith(*II, V);
  
      // EXTRQI only uses the lowest 64-bits of the first 128-bit vector
      // operand.
      if (Value *V = SimplifyDemandedVectorEltsLow(Op0, VWidth, 1)) {
        II->setArgOperand(0, V);
        return II;
      }
      break;
    }
  
    case Intrinsic::x86_sse4a_insertq: {
      Value *Op0 = II->getArgOperand(0);
      Value *Op1 = II->getArgOperand(1);
      unsigned VWidth = Op0->getType()->getVectorNumElements();
      assert(Op0->getType()->getPrimitiveSizeInBits() == 128 &&
             Op1->getType()->getPrimitiveSizeInBits() == 128 && VWidth == 2 &&
             Op1->getType()->getVectorNumElements() == 2 &&
             "Unexpected operand size");
  
      // See if we're dealing with constant values.
      Constant *C1 = dyn_cast<Constant>(Op1);
      ConstantInt *CI11 =
          C1 ? dyn_cast<ConstantInt>(C1->getAggregateElement((unsigned)1))
             : nullptr;
  
      // Attempt to simplify to a constant, shuffle vector or INSERTQI call.
      if (CI11) {
        APInt V11 = CI11->getValue();
        APInt Len = V11.zextOrTrunc(6);
        APInt Idx = V11.lshr(8).zextOrTrunc(6);
        if (Value *V = simplifyX86insertq(*II, Op0, Op1, Len, Idx, *Builder))
          return replaceInstUsesWith(*II, V);
      }
  
      // INSERTQ only uses the lowest 64-bits of the first 128-bit vector
      // operand.
      if (Value *V = SimplifyDemandedVectorEltsLow(Op0, VWidth, 1)) {
        II->setArgOperand(0, V);
        return II;
      }
      break;
    }
  
    case Intrinsic::x86_sse4a_insertqi: {
      // INSERTQI: Extract lowest Length bits from lower half of second source and
      // insert over first source starting at Index bit. The upper 64-bits are
      // undefined.
      Value *Op0 = II->getArgOperand(0);
      Value *Op1 = II->getArgOperand(1);
      unsigned VWidth0 = Op0->getType()->getVectorNumElements();
      unsigned VWidth1 = Op1->getType()->getVectorNumElements();
      assert(Op0->getType()->getPrimitiveSizeInBits() == 128 &&
             Op1->getType()->getPrimitiveSizeInBits() == 128 && VWidth0 == 2 &&
             VWidth1 == 2 && "Unexpected operand sizes");
  
      // See if we're dealing with constant values.
      ConstantInt *CILength = dyn_cast<ConstantInt>(II->getArgOperand(2));
      ConstantInt *CIIndex = dyn_cast<ConstantInt>(II->getArgOperand(3));
  
      // Attempt to simplify to a constant or shuffle vector.
      if (CILength && CIIndex) {
        APInt Len = CILength->getValue().zextOrTrunc(6);
        APInt Idx = CIIndex->getValue().zextOrTrunc(6);
        if (Value *V = simplifyX86insertq(*II, Op0, Op1, Len, Idx, *Builder))
          return replaceInstUsesWith(*II, V);
      }
  
      // INSERTQI only uses the lowest 64-bits of the first two 128-bit vector
      // operands.
      bool MadeChange = false;
      if (Value *V = SimplifyDemandedVectorEltsLow(Op0, VWidth0, 1)) {
        II->setArgOperand(0, V);
        MadeChange = true;
      }
      if (Value *V = SimplifyDemandedVectorEltsLow(Op1, VWidth1, 1)) {
        II->setArgOperand(1, V);
        MadeChange = true;
      }
      if (MadeChange)
        return II;
      break;
    }
  
    case Intrinsic::x86_sse41_pblendvb:
    case Intrinsic::x86_sse41_blendvps:
    case Intrinsic::x86_sse41_blendvpd:
    case Intrinsic::x86_avx_blendv_ps_256:
    case Intrinsic::x86_avx_blendv_pd_256:
    case Intrinsic::x86_avx2_pblendvb: {
      // Convert blendv* to vector selects if the mask is constant.
      // This optimization is convoluted because the intrinsic is defined as
      // getting a vector of floats or doubles for the ps and pd versions.
      // FIXME: That should be changed.
  
      Value *Op0 = II->getArgOperand(0);
      Value *Op1 = II->getArgOperand(1);
      Value *Mask = II->getArgOperand(2);
  
      // fold (blend A, A, Mask) -> A
      if (Op0 == Op1)
        return replaceInstUsesWith(CI, Op0);
  
      // Zero Mask - select 1st argument.
      if (isa<ConstantAggregateZero>(Mask))
        return replaceInstUsesWith(CI, Op0);
  
      // Constant Mask - select 1st/2nd argument lane based on top bit of mask.
      if (auto *ConstantMask = dyn_cast<ConstantDataVector>(Mask)) {
        Constant *NewSelector = getNegativeIsTrueBoolVec(ConstantMask);
        return SelectInst::Create(NewSelector, Op1, Op0, "blendv");
      }
      break;
    }
  
    case Intrinsic::x86_ssse3_pshuf_b_128:
    case Intrinsic::x86_avx2_pshuf_b:
      if (Value *V = simplifyX86pshufb(*II, *Builder))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_avx_vpermilvar_ps:
    case Intrinsic::x86_avx_vpermilvar_ps_256:
    case Intrinsic::x86_avx_vpermilvar_pd:
    case Intrinsic::x86_avx_vpermilvar_pd_256:
      if (Value *V = simplifyX86vpermilvar(*II, *Builder))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_avx2_permd:
    case Intrinsic::x86_avx2_permps:
      if (Value *V = simplifyX86vpermv(*II, *Builder))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_avx_vperm2f128_pd_256:
    case Intrinsic::x86_avx_vperm2f128_ps_256:
    case Intrinsic::x86_avx_vperm2f128_si_256:
    case Intrinsic::x86_avx2_vperm2i128:
      if (Value *V = simplifyX86vperm2(*II, *Builder))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_avx_maskload_ps:
    case Intrinsic::x86_avx_maskload_pd:
    case Intrinsic::x86_avx_maskload_ps_256:
    case Intrinsic::x86_avx_maskload_pd_256:
    case Intrinsic::x86_avx2_maskload_d:
    case Intrinsic::x86_avx2_maskload_q:
    case Intrinsic::x86_avx2_maskload_d_256:
    case Intrinsic::x86_avx2_maskload_q_256:
      if (Instruction *I = simplifyX86MaskedLoad(*II, *this))
        return I;
      break;
  
    case Intrinsic::x86_sse2_maskmov_dqu:
    case Intrinsic::x86_avx_maskstore_ps:
    case Intrinsic::x86_avx_maskstore_pd:
    case Intrinsic::x86_avx_maskstore_ps_256:
    case Intrinsic::x86_avx_maskstore_pd_256:
    case Intrinsic::x86_avx2_maskstore_d:
    case Intrinsic::x86_avx2_maskstore_q:
    case Intrinsic::x86_avx2_maskstore_d_256:
    case Intrinsic::x86_avx2_maskstore_q_256:
      if (simplifyX86MaskedStore(*II, *this))
        return nullptr;
      break;
  
    case Intrinsic::x86_xop_vpcomb:
    case Intrinsic::x86_xop_vpcomd:
    case Intrinsic::x86_xop_vpcomq:
    case Intrinsic::x86_xop_vpcomw:
      if (Value *V = simplifyX86vpcom(*II, *Builder, true))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::x86_xop_vpcomub:
    case Intrinsic::x86_xop_vpcomud:
    case Intrinsic::x86_xop_vpcomuq:
    case Intrinsic::x86_xop_vpcomuw:
      if (Value *V = simplifyX86vpcom(*II, *Builder, false))
        return replaceInstUsesWith(*II, V);
      break;
  
    case Intrinsic::ppc_altivec_vperm:
      // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
      // Note that ppc_altivec_vperm has a big-endian bias, so when creating
      // a vectorshuffle for little endian, we must undo the transformation
      // performed on vec_perm in altivec.h.  That is, we must complement
      // the permutation mask with respect to 31 and reverse the order of
      // V1 and V2.
      if (Constant *Mask = dyn_cast<Constant>(II->getArgOperand(2))) {
        assert(Mask->getType()->getVectorNumElements() == 16 &&
               "Bad type for intrinsic!");
  
        // Check that all of the elements are integer constants or undefs.
        bool AllEltsOk = true;
        for (unsigned i = 0; i != 16; ++i) {
          Constant *Elt = Mask->getAggregateElement(i);
          if (!Elt || !(isa<ConstantInt>(Elt) || isa<UndefValue>(Elt))) {
            AllEltsOk = false;
            break;
          }
        }
  
        if (AllEltsOk) {
          // Cast the input vectors to byte vectors.
          Value *Op0 = Builder->CreateBitCast(II->getArgOperand(0),
                                              Mask->getType());
          Value *Op1 = Builder->CreateBitCast(II->getArgOperand(1),
                                              Mask->getType());
          Value *Result = UndefValue::get(Op0->getType());
  
          // Only extract each element once.
          Value *ExtractedElts[32];
          memset(ExtractedElts, 0, sizeof(ExtractedElts));
  
          for (unsigned i = 0; i != 16; ++i) {
            if (isa<UndefValue>(Mask->getAggregateElement(i)))
              continue;
            unsigned Idx =
              cast<ConstantInt>(Mask->getAggregateElement(i))->getZExtValue();
            Idx &= 31;  // Match the hardware behavior.
            if (DL.isLittleEndian())
              Idx = 31 - Idx;
  
            if (!ExtractedElts[Idx]) {
              Value *Op0ToUse = (DL.isLittleEndian()) ? Op1 : Op0;
              Value *Op1ToUse = (DL.isLittleEndian()) ? Op0 : Op1;
              ExtractedElts[Idx] =
                Builder->CreateExtractElement(Idx < 16 ? Op0ToUse : Op1ToUse,
                                              Builder->getInt32(Idx&15));
            }
  
            // Insert this value into the result vector.
            Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
                                                  Builder->getInt32(i));
          }
          return CastInst::Create(Instruction::BitCast, Result, CI.getType());
        }
      }
      break;
  
    case Intrinsic::arm_neon_vld1:
    case Intrinsic::arm_neon_vld2:
    case Intrinsic::arm_neon_vld3:
    case Intrinsic::arm_neon_vld4:
    case Intrinsic::arm_neon_vld2lane:
    case Intrinsic::arm_neon_vld3lane:
    case Intrinsic::arm_neon_vld4lane:
    case Intrinsic::arm_neon_vst1:
    case Intrinsic::arm_neon_vst2:
    case Intrinsic::arm_neon_vst3:
    case Intrinsic::arm_neon_vst4:
    case Intrinsic::arm_neon_vst2lane:
    case Intrinsic::arm_neon_vst3lane:
    case Intrinsic::arm_neon_vst4lane: {
      unsigned MemAlign = getKnownAlignment(II->getArgOperand(0), DL, II, AC, DT);
      unsigned AlignArg = II->getNumArgOperands() - 1;
      ConstantInt *IntrAlign = dyn_cast<ConstantInt>(II->getArgOperand(AlignArg));
      if (IntrAlign && IntrAlign->getZExtValue() < MemAlign) {
        II->setArgOperand(AlignArg,
                          ConstantInt::get(Type::getInt32Ty(II->getContext()),
                                           MemAlign, false));
        return II;
      }
      break;
    }
  
    case Intrinsic::arm_neon_vmulls:
    case Intrinsic::arm_neon_vmullu:
    case Intrinsic::aarch64_neon_smull:
    case Intrinsic::aarch64_neon_umull: {
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
  
      // Handle mul by zero first:
      if (isa<ConstantAggregateZero>(Arg0) || isa<ConstantAggregateZero>(Arg1)) {
        return replaceInstUsesWith(CI, ConstantAggregateZero::get(II->getType()));
      }
  
      // Check for constant LHS & RHS - in this case we just simplify.
      bool Zext = (II->getIntrinsicID() == Intrinsic::arm_neon_vmullu ||
                   II->getIntrinsicID() == Intrinsic::aarch64_neon_umull);
      VectorType *NewVT = cast<VectorType>(II->getType());
      if (Constant *CV0 = dyn_cast<Constant>(Arg0)) {
        if (Constant *CV1 = dyn_cast<Constant>(Arg1)) {
          CV0 = ConstantExpr::getIntegerCast(CV0, NewVT, /*isSigned=*/!Zext);
          CV1 = ConstantExpr::getIntegerCast(CV1, NewVT, /*isSigned=*/!Zext);
  
          return replaceInstUsesWith(CI, ConstantExpr::getMul(CV0, CV1));
        }
  
        // Couldn't simplify - canonicalize constant to the RHS.
        std::swap(Arg0, Arg1);
      }
  
      // Handle mul by one:
      if (Constant *CV1 = dyn_cast<Constant>(Arg1))
        if (ConstantInt *Splat =
                dyn_cast_or_null<ConstantInt>(CV1->getSplatValue()))
          if (Splat->isOne())
            return CastInst::CreateIntegerCast(Arg0, II->getType(),
                                               /*isSigned=*/!Zext);
  
      break;
    }
  
    case Intrinsic::amdgcn_rcp: {
      if (const ConstantFP *C = dyn_cast<ConstantFP>(II->getArgOperand(0))) {
        const APFloat &ArgVal = C->getValueAPF();
        APFloat Val(ArgVal.getSemantics(), 1.0);
        APFloat::opStatus Status = Val.divide(ArgVal,
                                              APFloat::rmNearestTiesToEven);
        // Only do this if it was exact and therefore not dependent on the
        // rounding mode.
        if (Status == APFloat::opOK)
          return replaceInstUsesWith(CI, ConstantFP::get(II->getContext(), Val));
      }
  
      break;
    }
    case Intrinsic::amdgcn_frexp_mant:
    case Intrinsic::amdgcn_frexp_exp: {
      Value *Src = II->getArgOperand(0);
      if (const ConstantFP *C = dyn_cast<ConstantFP>(Src)) {
        int Exp;
        APFloat Significand = frexp(C->getValueAPF(), Exp,
                                    APFloat::rmNearestTiesToEven);
  
        if (II->getIntrinsicID() == Intrinsic::amdgcn_frexp_mant) {
          return replaceInstUsesWith(CI, ConstantFP::get(II->getContext(),
                                                         Significand));
        }
  
        // Match instruction special case behavior.
        if (Exp == APFloat::IEK_NaN || Exp == APFloat::IEK_Inf)
          Exp = 0;
  
        return replaceInstUsesWith(CI, ConstantInt::get(II->getType(), Exp));
      }
  
      if (isa<UndefValue>(Src))
        return replaceInstUsesWith(CI, UndefValue::get(II->getType()));
  
      break;
    }
    case Intrinsic::stackrestore: {
      // If the save is right next to the restore, remove the restore.  This can
      // happen when variable allocas are DCE'd.
      if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getArgOperand(0))) {
        if (SS->getIntrinsicID() == Intrinsic::stacksave) {
          if (&*++SS->getIterator() == II)
            return eraseInstFromFunction(CI);
        }
      }
  
      // Scan down this block to see if there is another stack restore in the
      // same block without an intervening call/alloca.
      BasicBlock::iterator BI(II);
      TerminatorInst *TI = II->getParent()->getTerminator();
      bool CannotRemove = false;
      for (++BI; &*BI != TI; ++BI) {
        if (isa<AllocaInst>(BI)) {
          CannotRemove = true;
          break;
        }
        if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
          if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
            // If there is a stackrestore below this one, remove this one.
            if (II->getIntrinsicID() == Intrinsic::stackrestore)
              return eraseInstFromFunction(CI);
  
            // Bail if we cross over an intrinsic with side effects, such as
            // llvm.stacksave, llvm.read_register, or llvm.setjmp.
            if (II->mayHaveSideEffects()) {
              CannotRemove = true;
              break;
            }
          } else {
            // If we found a non-intrinsic call, we can't remove the stack
            // restore.
            CannotRemove = true;
            break;
          }
        }
      }
  
      // If the stack restore is in a return, resume, or unwind block and if there
      // are no allocas or calls between the restore and the return, nuke the
      // restore.
      if (!CannotRemove && (isa<ReturnInst>(TI) || isa<ResumeInst>(TI)))
        return eraseInstFromFunction(CI);
      break;
    }
    case Intrinsic::lifetime_start:
      if (removeTriviallyEmptyRange(*II, Intrinsic::lifetime_start,
                                    Intrinsic::lifetime_end, *this))
        return nullptr;
      break;
    case Intrinsic::assume: {
      Value *IIOperand = II->getArgOperand(0);
      // Remove an assume if it is immediately followed by an identical assume.
      if (match(II->getNextNode(),
                m_Intrinsic<Intrinsic::assume>(m_Specific(IIOperand))))
        return eraseInstFromFunction(CI);
  
      // Canonicalize assume(a && b) -> assume(a); assume(b);
      // Note: New assumption intrinsics created here are registered by
      // the InstCombineIRInserter object.
      Value *AssumeIntrinsic = II->getCalledValue(), *A, *B;
      if (match(IIOperand, m_And(m_Value(A), m_Value(B)))) {
        Builder->CreateCall(AssumeIntrinsic, A, II->getName());
        Builder->CreateCall(AssumeIntrinsic, B, II->getName());
        return eraseInstFromFunction(*II);
      }
      // assume(!(a || b)) -> assume(!a); assume(!b);
      if (match(IIOperand, m_Not(m_Or(m_Value(A), m_Value(B))))) {
        Builder->CreateCall(AssumeIntrinsic, Builder->CreateNot(A),
                            II->getName());
        Builder->CreateCall(AssumeIntrinsic, Builder->CreateNot(B),
                            II->getName());
        return eraseInstFromFunction(*II);
      }
  
      // assume( (load addr) != null ) -> add 'nonnull' metadata to load
      // (if assume is valid at the load)
      if (ICmpInst* ICmp = dyn_cast<ICmpInst>(IIOperand)) {
        Value *LHS = ICmp->getOperand(0);
        Value *RHS = ICmp->getOperand(1);
        if (ICmpInst::ICMP_NE == ICmp->getPredicate() &&
            isa<LoadInst>(LHS) &&
            isa<Constant>(RHS) &&
            RHS->getType()->isPointerTy() &&
            cast<Constant>(RHS)->isNullValue()) {
          LoadInst* LI = cast<LoadInst>(LHS);
          if (isValidAssumeForContext(II, LI, DT)) {
            MDNode *MD = MDNode::get(II->getContext(), None);
            LI->setMetadata(LLVMContext::MD_nonnull, MD);
            return eraseInstFromFunction(*II);
          }
        }
        // TODO: apply nonnull return attributes to calls and invokes
        // TODO: apply range metadata for range check patterns?
      }
      // If there is a dominating assume with the same condition as this one,
      // then this one is redundant, and should be removed.
      APInt KnownZero(1, 0), KnownOne(1, 0);
      computeKnownBits(IIOperand, KnownZero, KnownOne, 0, II);
      if (KnownOne.isAllOnesValue())
        return eraseInstFromFunction(*II);
  
      break;
    }
    case Intrinsic::experimental_gc_relocate: {
      // Translate facts known about a pointer before relocating into
      // facts about the relocate value, while being careful to
      // preserve relocation semantics.
      Value *DerivedPtr = cast<GCRelocateInst>(II)->getDerivedPtr();
  
      // Remove the relocation if unused, note that this check is required
      // to prevent the cases below from looping forever.
      if (II->use_empty())
        return eraseInstFromFunction(*II);
  
      // Undef is undef, even after relocation.
      // TODO: provide a hook for this in GCStrategy.  This is clearly legal for
      // most practical collectors, but there was discussion in the review thread
      // about whether it was legal for all possible collectors.
      if (isa<UndefValue>(DerivedPtr))
        // Use undef of gc_relocate's type to replace it.
        return replaceInstUsesWith(*II, UndefValue::get(II->getType()));
  
      if (auto *PT = dyn_cast<PointerType>(II->getType())) {
        // The relocation of null will be null for most any collector.
        // TODO: provide a hook for this in GCStrategy.  There might be some
        // weird collector this property does not hold for.
        if (isa<ConstantPointerNull>(DerivedPtr))
          // Use null-pointer of gc_relocate's type to replace it.
          return replaceInstUsesWith(*II, ConstantPointerNull::get(PT));
  
        // isKnownNonNull -> nonnull attribute
        if (isKnownNonNullAt(DerivedPtr, II, DT, TLI))
          II->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
      }
  
      // TODO: bitcast(relocate(p)) -> relocate(bitcast(p))
      // Canonicalize on the type from the uses to the defs
  
      // TODO: relocate((gep p, C, C2, ...)) -> gep(relocate(p), C, C2, ...)
      break;
    }
    }
  
    return visitCallSite(II);
  }
  
  // InvokeInst simplification
  //
  Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
    return visitCallSite(&II);
  }
  
  /// If this cast does not affect the value passed through the varargs area, we
  /// can eliminate the use of the cast.
  static bool isSafeToEliminateVarargsCast(const CallSite CS,
                                           const DataLayout &DL,
                                           const CastInst *const CI,
                                           const int ix) {
    if (!CI->isLosslessCast())
      return false;
  
    // If this is a GC intrinsic, avoid munging types.  We need types for
    // statepoint reconstruction in SelectionDAG.
    // TODO: This is probably something which should be expanded to all
    // intrinsics since the entire point of intrinsics is that
    // they are understandable by the optimizer.
    if (isStatepoint(CS) || isGCRelocate(CS) || isGCResult(CS))
      return false;
  
    // The size of ByVal or InAlloca arguments is derived from the type, so we
    // can't change to a type with a different size.  If the size were
    // passed explicitly we could avoid this check.
    if (!CS.isByValOrInAllocaArgument(ix))
      return true;
  
    Type* SrcTy =
              cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
    Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
    if (!SrcTy->isSized() || !DstTy->isSized())
      return false;
    if (DL.getTypeAllocSize(SrcTy) != DL.getTypeAllocSize(DstTy))
      return false;
    return true;
  }
  
  Instruction *InstCombiner::tryOptimizeCall(CallInst *CI) {
    if (!CI->getCalledFunction()) return nullptr;
  
    auto InstCombineRAUW = [this](Instruction *From, Value *With) {
      replaceInstUsesWith(*From, With);
    };
    LibCallSimplifier Simplifier(DL, TLI, InstCombineRAUW);
    if (Value *With = Simplifier.optimizeCall(CI)) {
      ++NumSimplified;
      return CI->use_empty() ? CI : replaceInstUsesWith(*CI, With);
    }
  
    return nullptr;
  }
  
  static IntrinsicInst *findInitTrampolineFromAlloca(Value *TrampMem) {
    // Strip off at most one level of pointer casts, looking for an alloca.  This
    // is good enough in practice and simpler than handling any number of casts.
    Value *Underlying = TrampMem->stripPointerCasts();
    if (Underlying != TrampMem &&
        (!Underlying->hasOneUse() || Underlying->user_back() != TrampMem))
      return nullptr;
    if (!isa<AllocaInst>(Underlying))
      return nullptr;
  
    IntrinsicInst *InitTrampoline = nullptr;
    for (User *U : TrampMem->users()) {
      IntrinsicInst *II = dyn_cast<IntrinsicInst>(U);
      if (!II)
        return nullptr;
      if (II->getIntrinsicID() == Intrinsic::init_trampoline) {
        if (InitTrampoline)
          // More than one init_trampoline writes to this value.  Give up.
          return nullptr;
        InitTrampoline = II;
        continue;
      }
      if (II->getIntrinsicID() == Intrinsic::adjust_trampoline)
        // Allow any number of calls to adjust.trampoline.
        continue;
      return nullptr;
    }
  
    // No call to init.trampoline found.
    if (!InitTrampoline)
      return nullptr;
  
    // Check that the alloca is being used in the expected way.
    if (InitTrampoline->getOperand(0) != TrampMem)
      return nullptr;
  
    return InitTrampoline;
  }
  
  static IntrinsicInst *findInitTrampolineFromBB(IntrinsicInst *AdjustTramp,
                                                 Value *TrampMem) {
    // Visit all the previous instructions in the basic block, and try to find a
    // init.trampoline which has a direct path to the adjust.trampoline.
    for (BasicBlock::iterator I = AdjustTramp->getIterator(),
                              E = AdjustTramp->getParent()->begin();
         I != E;) {
      Instruction *Inst = &*--I;
      if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
        if (II->getIntrinsicID() == Intrinsic::init_trampoline &&
            II->getOperand(0) == TrampMem)
          return II;
      if (Inst->mayWriteToMemory())
        return nullptr;
    }
    return nullptr;
  }
  
  // Given a call to llvm.adjust.trampoline, find and return the corresponding
  // call to llvm.init.trampoline if the call to the trampoline can be optimized
  // to a direct call to a function.  Otherwise return NULL.
  //
  static IntrinsicInst *findInitTrampoline(Value *Callee) {
    Callee = Callee->stripPointerCasts();
    IntrinsicInst *AdjustTramp = dyn_cast<IntrinsicInst>(Callee);
    if (!AdjustTramp ||
        AdjustTramp->getIntrinsicID() != Intrinsic::adjust_trampoline)
      return nullptr;
  
    Value *TrampMem = AdjustTramp->getOperand(0);
  
    if (IntrinsicInst *IT = findInitTrampolineFromAlloca(TrampMem))
      return IT;
    if (IntrinsicInst *IT = findInitTrampolineFromBB(AdjustTramp, TrampMem))
      return IT;
    return nullptr;
  }
  
  /// Improvements for call and invoke instructions.
  Instruction *InstCombiner::visitCallSite(CallSite CS) {
  
    if (isAllocLikeFn(CS.getInstruction(), TLI))
      return visitAllocSite(*CS.getInstruction());
  
    bool Changed = false;
  
    // Mark any parameters that are known to be non-null with the nonnull
    // attribute.  This is helpful for inlining calls to functions with null
    // checks on their arguments.
    SmallVector<unsigned, 4> Indices;
    unsigned ArgNo = 0;
  
    for (Value *V : CS.args()) {
      if (V->getType()->isPointerTy() &&
          !CS.paramHasAttr(ArgNo + 1, Attribute::NonNull) &&
          isKnownNonNullAt(V, CS.getInstruction(), DT, TLI))
        Indices.push_back(ArgNo + 1);
      ArgNo++;
    }
  
    assert(ArgNo == CS.arg_size() && "sanity check");
  
    if (!Indices.empty()) {
      AttributeSet AS = CS.getAttributes();
      LLVMContext &Ctx = CS.getInstruction()->getContext();
      AS = AS.addAttribute(Ctx, Indices,
                           Attribute::get(Ctx, Attribute::NonNull));
      CS.setAttributes(AS);
      Changed = true;
    }
  
    // If the callee is a pointer to a function, attempt to move any casts to the
    // arguments of the call/invoke.
    Value *Callee = CS.getCalledValue();
    if (!isa<Function>(Callee) && transformConstExprCastCall(CS))
      return nullptr;
  
    if (Function *CalleeF = dyn_cast<Function>(Callee)) {
      // Remove the convergent attr on calls when the callee is not convergent.
      if (CS.isConvergent() && !CalleeF->isConvergent()) {
        DEBUG(dbgs() << "Removing convergent attr from instr "
                     << CS.getInstruction() << "\n");
        CS.setNotConvergent();
        return CS.getInstruction();
      }
  
      // If the call and callee calling conventions don't match, this call must
      // be unreachable, as the call is undefined.
      if (CalleeF->getCallingConv() != CS.getCallingConv() &&
          // Only do this for calls to a function with a body.  A prototype may
          // not actually end up matching the implementation's calling conv for a
          // variety of reasons (e.g. it may be written in assembly).
          !CalleeF->isDeclaration()) {
        Instruction *OldCall = CS.getInstruction();
        new StoreInst(ConstantInt::getTrue(Callee->getContext()),
                  UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
                                    OldCall);
        // If OldCall does not return void then replaceAllUsesWith undef.
        // This allows ValueHandlers and custom metadata to adjust itself.
        if (!OldCall->getType()->isVoidTy())
          replaceInstUsesWith(*OldCall, UndefValue::get(OldCall->getType()));
        if (isa<CallInst>(OldCall))
          return eraseInstFromFunction(*OldCall);
  
        // We cannot remove an invoke, because it would change the CFG, just
        // change the callee to a null pointer.
        cast<InvokeInst>(OldCall)->setCalledFunction(
                                      Constant::getNullValue(CalleeF->getType()));
        return nullptr;
      }
    }
  
    if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
      // If CS does not return void then replaceAllUsesWith undef.
      // This allows ValueHandlers and custom metadata to adjust itself.
      if (!CS.getInstruction()->getType()->isVoidTy())
        replaceInstUsesWith(*CS.getInstruction(),
                            UndefValue::get(CS.getInstruction()->getType()));
  
      if (isa<InvokeInst>(CS.getInstruction())) {
        // Can't remove an invoke because we cannot change the CFG.
        return nullptr;
      }
  
      // This instruction is not reachable, just remove it.  We insert a store to
      // undef so that we know that this code is not reachable, despite the fact
      // that we can't modify the CFG here.
      new StoreInst(ConstantInt::getTrue(Callee->getContext()),
                    UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
                    CS.getInstruction());
  
      return eraseInstFromFunction(*CS.getInstruction());
    }
  
    if (IntrinsicInst *II = findInitTrampoline(Callee))
      return transformCallThroughTrampoline(CS, II);
  
    PointerType *PTy = cast<PointerType>(Callee->getType());
    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
    if (FTy->isVarArg()) {
      int ix = FTy->getNumParams();
      // See if we can optimize any arguments passed through the varargs area of
      // the call.
      for (CallSite::arg_iterator I = CS.arg_begin() + FTy->getNumParams(),
             E = CS.arg_end(); I != E; ++I, ++ix) {
        CastInst *CI = dyn_cast<CastInst>(*I);
        if (CI && isSafeToEliminateVarargsCast(CS, DL, CI, ix)) {
          *I = CI->getOperand(0);
          Changed = true;
        }
      }
    }
  
    if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
      // Inline asm calls cannot throw - mark them 'nounwind'.
      CS.setDoesNotThrow();
      Changed = true;
    }
  
    // Try to optimize the call if possible, we require DataLayout for most of
    // this.  None of these calls are seen as possibly dead so go ahead and
    // delete the instruction now.
    if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
      Instruction *I = tryOptimizeCall(CI);
      // If we changed something return the result, etc. Otherwise let
      // the fallthrough check.
      if (I) return eraseInstFromFunction(*I);
    }
  
    return Changed ? CS.getInstruction() : nullptr;
  }
  
  /// If the callee is a constexpr cast of a function, attempt to move the cast to
  /// the arguments of the call/invoke.
  bool InstCombiner::transformConstExprCastCall(CallSite CS) {
    Function *Callee =
      dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
    if (!Callee)
      return false;
    // The prototype of thunks are a lie, don't try to directly call such
    // functions.
    if (Callee->hasFnAttribute("thunk"))
      return false;
    Instruction *Caller = CS.getInstruction();
    const AttributeSet &CallerPAL = CS.getAttributes();
  
    // Okay, this is a cast from a function to a different type.  Unless doing so
    // would cause a type conversion of one of our arguments, change this call to
    // be a direct call with arguments casted to the appropriate types.
    //
    FunctionType *FT = Callee->getFunctionType();
    Type *OldRetTy = Caller->getType();
    Type *NewRetTy = FT->getReturnType();
  
    // Check to see if we are changing the return type...
    if (OldRetTy != NewRetTy) {
  
      if (NewRetTy->isStructTy())
        return false; // TODO: Handle multiple return values.
  
      if (!CastInst::isBitOrNoopPointerCastable(NewRetTy, OldRetTy, DL)) {
        if (Callee->isDeclaration())
          return false;   // Cannot transform this return value.
  
        if (!Caller->use_empty() &&
            // void -> non-void is handled specially
            !NewRetTy->isVoidTy())
          return false;   // Cannot transform this return value.
      }
  
      if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
        AttrBuilder RAttrs(CallerPAL, AttributeSet::ReturnIndex);
        if (RAttrs.overlaps(AttributeFuncs::typeIncompatible(NewRetTy)))
          return false;   // Attribute not compatible with transformed value.
      }
  
      // If the callsite is an invoke instruction, and the return value is used by
      // a PHI node in a successor, we cannot change the return type of the call
      // because there is no place to put the cast instruction (without breaking
      // the critical edge).  Bail out in this case.
      if (!Caller->use_empty())
        if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
          for (User *U : II->users())
            if (PHINode *PN = dyn_cast<PHINode>(U))
              if (PN->getParent() == II->getNormalDest() ||
                  PN->getParent() == II->getUnwindDest())
                return false;
    }
  
    unsigned NumActualArgs = CS.arg_size();
    unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
  
    // Prevent us turning:
    // declare void @takes_i32_inalloca(i32* inalloca)
    //  call void bitcast (void (i32*)* @takes_i32_inalloca to void (i32)*)(i32 0)
    //
    // into:
    //  call void @takes_i32_inalloca(i32* null)
    //
    //  Similarly, avoid folding away bitcasts of byval calls.
    if (Callee->getAttributes().hasAttrSomewhere(Attribute::InAlloca) ||
        Callee->getAttributes().hasAttrSomewhere(Attribute::ByVal))
      return false;
  
    CallSite::arg_iterator AI = CS.arg_begin();
    for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
      Type *ParamTy = FT->getParamType(i);
      Type *ActTy = (*AI)->getType();
  
      if (!CastInst::isBitOrNoopPointerCastable(ActTy, ParamTy, DL))
        return false;   // Cannot transform this parameter value.
  
      if (AttrBuilder(CallerPAL.getParamAttributes(i + 1), i + 1).
            overlaps(AttributeFuncs::typeIncompatible(ParamTy)))
        return false;   // Attribute not compatible with transformed value.
  
      if (CS.isInAllocaArgument(i))
        return false;   // Cannot transform to and from inalloca.
  
      // If the parameter is passed as a byval argument, then we have to have a
      // sized type and the sized type has to have the same size as the old type.
      if (ParamTy != ActTy &&
          CallerPAL.getParamAttributes(i + 1).hasAttribute(i + 1,
                                                           Attribute::ByVal)) {
        PointerType *ParamPTy = dyn_cast<PointerType>(ParamTy);
        if (!ParamPTy || !ParamPTy->getElementType()->isSized())
          return false;
  
        Type *CurElTy = ActTy->getPointerElementType();
        if (DL.getTypeAllocSize(CurElTy) !=
            DL.getTypeAllocSize(ParamPTy->getElementType()))
          return false;
      }
    }
  
    if (Callee->isDeclaration()) {
      // Do not delete arguments unless we have a function body.
      if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
        return false;
  
      // If the callee is just a declaration, don't change the varargsness of the
      // call.  We don't want to introduce a varargs call where one doesn't
      // already exist.
      PointerType *APTy = cast<PointerType>(CS.getCalledValue()->getType());
      if (FT->isVarArg()!=cast<FunctionType>(APTy->getElementType())->isVarArg())
        return false;
  
      // If both the callee and the cast type are varargs, we still have to make
      // sure the number of fixed parameters are the same or we have the same
      // ABI issues as if we introduce a varargs call.
      if (FT->isVarArg() &&
          cast<FunctionType>(APTy->getElementType())->isVarArg() &&
          FT->getNumParams() !=
          cast<FunctionType>(APTy->getElementType())->getNumParams())
        return false;
    }
  
    if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
        !CallerPAL.isEmpty())
      // In this case we have more arguments than the new function type, but we
      // won't be dropping them.  Check that these extra arguments have attributes
      // that are compatible with being a vararg call argument.
      for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
        unsigned Index = CallerPAL.getSlotIndex(i - 1);
        if (Index <= FT->getNumParams())
          break;
  
        // Check if it has an attribute that's incompatible with varargs.
        AttributeSet PAttrs = CallerPAL.getSlotAttributes(i - 1);
        if (PAttrs.hasAttribute(Index, Attribute::StructRet))
          return false;
      }
  
  
    // Okay, we decided that this is a safe thing to do: go ahead and start
    // inserting cast instructions as necessary.
    std::vector<Value*> Args;
    Args.reserve(NumActualArgs);
    SmallVector<AttributeSet, 8> attrVec;
    attrVec.reserve(NumCommonArgs);
  
    // Get any return attributes.
    AttrBuilder RAttrs(CallerPAL, AttributeSet::ReturnIndex);
  
    // If the return value is not being used, the type may not be compatible
    // with the existing attributes.  Wipe out any problematic attributes.
    RAttrs.remove(AttributeFuncs::typeIncompatible(NewRetTy));
  
    // Add the new return attributes.
    if (RAttrs.hasAttributes())
      attrVec.push_back(AttributeSet::get(Caller->getContext(),
                                          AttributeSet::ReturnIndex, RAttrs));
  
    AI = CS.arg_begin();
    for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
      Type *ParamTy = FT->getParamType(i);
  
      if ((*AI)->getType() == ParamTy) {
        Args.push_back(*AI);
      } else {
        Args.push_back(Builder->CreateBitOrPointerCast(*AI, ParamTy));
      }
  
      // Add any parameter attributes.
      AttrBuilder PAttrs(CallerPAL.getParamAttributes(i + 1), i + 1);
      if (PAttrs.hasAttributes())
        attrVec.push_back(AttributeSet::get(Caller->getContext(), i + 1,
                                            PAttrs));
    }
  
    // If the function takes more arguments than the call was taking, add them
    // now.
    for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
      Args.push_back(Constant::getNullValue(FT->getParamType(i)));
  
    // If we are removing arguments to the function, emit an obnoxious warning.
    if (FT->getNumParams() < NumActualArgs) {
      // TODO: if (!FT->isVarArg()) this call may be unreachable. PR14722
      if (FT->isVarArg()) {
        // Add all of the arguments in their promoted form to the arg list.
        for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
          Type *PTy = getPromotedType((*AI)->getType());
          if (PTy != (*AI)->getType()) {
            // Must promote to pass through va_arg area!
            Instruction::CastOps opcode =
              CastInst::getCastOpcode(*AI, false, PTy, false);
            Args.push_back(Builder->CreateCast(opcode, *AI, PTy));
          } else {
            Args.push_back(*AI);
          }
  
          // Add any parameter attributes.
          AttrBuilder PAttrs(CallerPAL.getParamAttributes(i + 1), i + 1);
          if (PAttrs.hasAttributes())
            attrVec.push_back(AttributeSet::get(FT->getContext(), i + 1,
                                                PAttrs));
        }
      }
    }
  
    AttributeSet FnAttrs = CallerPAL.getFnAttributes();
    if (CallerPAL.hasAttributes(AttributeSet::FunctionIndex))
      attrVec.push_back(AttributeSet::get(Callee->getContext(), FnAttrs));
  
    if (NewRetTy->isVoidTy())
      Caller->setName("");   // Void type should not have a name.
  
    const AttributeSet &NewCallerPAL = AttributeSet::get(Callee->getContext(),
                                                         attrVec);
  
    SmallVector<OperandBundleDef, 1> OpBundles;
    CS.getOperandBundlesAsDefs(OpBundles);
  
    Instruction *NC;
    if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
      NC = Builder->CreateInvoke(Callee, II->getNormalDest(), II->getUnwindDest(),
                                 Args, OpBundles);
      NC->takeName(II);
      cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
      cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
    } else {
      CallInst *CI = cast<CallInst>(Caller);
      NC = Builder->CreateCall(Callee, Args, OpBundles);
      NC->takeName(CI);
      if (CI->isTailCall())
        cast<CallInst>(NC)->setTailCall();
      cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
      cast<CallInst>(NC)->setAttributes(NewCallerPAL);
    }
  
    // Insert a cast of the return type as necessary.
    Value *NV = NC;
    if (OldRetTy != NV->getType() && !Caller->use_empty()) {
      if (!NV->getType()->isVoidTy()) {
        NV = NC = CastInst::CreateBitOrPointerCast(NC, OldRetTy);
        NC->setDebugLoc(Caller->getDebugLoc());
  
        // If this is an invoke instruction, we should insert it after the first
        // non-phi, instruction in the normal successor block.
        if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
          BasicBlock::iterator I = II->getNormalDest()->getFirstInsertionPt();
          InsertNewInstBefore(NC, *I);
        } else {
          // Otherwise, it's a call, just insert cast right after the call.
          InsertNewInstBefore(NC, *Caller);
        }
        Worklist.AddUsersToWorkList(*Caller);
      } else {
        NV = UndefValue::get(Caller->getType());
      }
    }
  
    if (!Caller->use_empty())
      replaceInstUsesWith(*Caller, NV);
    else if (Caller->hasValueHandle()) {
      if (OldRetTy == NV->getType())
        ValueHandleBase::ValueIsRAUWd(Caller, NV);
      else
        // We cannot call ValueIsRAUWd with a different type, and the
        // actual tracked value will disappear.
        ValueHandleBase::ValueIsDeleted(Caller);
    }
  
    eraseInstFromFunction(*Caller);
    return true;
  }
  
  /// Turn a call to a function created by init_trampoline / adjust_trampoline
  /// intrinsic pair into a direct call to the underlying function.
  Instruction *
  InstCombiner::transformCallThroughTrampoline(CallSite CS,
                                               IntrinsicInst *Tramp) {
    Value *Callee = CS.getCalledValue();
    PointerType *PTy = cast<PointerType>(Callee->getType());
    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
    const AttributeSet &Attrs = CS.getAttributes();
  
    // If the call already has the 'nest' attribute somewhere then give up -
    // otherwise 'nest' would occur twice after splicing in the chain.
    if (Attrs.hasAttrSomewhere(Attribute::Nest))
      return nullptr;
  
    assert(Tramp &&
           "transformCallThroughTrampoline called with incorrect CallSite.");
  
    Function *NestF =cast<Function>(Tramp->getArgOperand(1)->stripPointerCasts());
    FunctionType *NestFTy = cast<FunctionType>(NestF->getValueType());
  
    const AttributeSet &NestAttrs = NestF->getAttributes();
    if (!NestAttrs.isEmpty()) {
      unsigned NestIdx = 1;
      Type *NestTy = nullptr;
      AttributeSet NestAttr;
  
      // Look for a parameter marked with the 'nest' attribute.
      for (FunctionType::param_iterator I = NestFTy->param_begin(),
           E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
        if (NestAttrs.hasAttribute(NestIdx, Attribute::Nest)) {
          // Record the parameter type and any other attributes.
          NestTy = *I;
          NestAttr = NestAttrs.getParamAttributes(NestIdx);
          break;
        }
  
      if (NestTy) {
        Instruction *Caller = CS.getInstruction();
        std::vector<Value*> NewArgs;
        NewArgs.reserve(CS.arg_size() + 1);
  
        SmallVector<AttributeSet, 8> NewAttrs;
        NewAttrs.reserve(Attrs.getNumSlots() + 1);
  
        // Insert the nest argument into the call argument list, which may
        // mean appending it.  Likewise for attributes.
  
        // Add any result attributes.
        if (Attrs.hasAttributes(AttributeSet::ReturnIndex))
          NewAttrs.push_back(AttributeSet::get(Caller->getContext(),
                                               Attrs.getRetAttributes()));
  
        {
          unsigned Idx = 1;
          CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
          do {
            if (Idx == NestIdx) {
              // Add the chain argument and attributes.
              Value *NestVal = Tramp->getArgOperand(2);
              if (NestVal->getType() != NestTy)
                NestVal = Builder->CreateBitCast(NestVal, NestTy, "nest");
              NewArgs.push_back(NestVal);
              NewAttrs.push_back(AttributeSet::get(Caller->getContext(),
                                                   NestAttr));
            }
  
            if (I == E)
              break;
  
            // Add the original argument and attributes.
            NewArgs.push_back(*I);
            AttributeSet Attr = Attrs.getParamAttributes(Idx);
            if (Attr.hasAttributes(Idx)) {
              AttrBuilder B(Attr, Idx);
              NewAttrs.push_back(AttributeSet::get(Caller->getContext(),
                                                   Idx + (Idx >= NestIdx), B));
            }
  
            ++Idx;
            ++I;
          } while (1);
        }
  
        // Add any function attributes.
        if (Attrs.hasAttributes(AttributeSet::FunctionIndex))
          NewAttrs.push_back(AttributeSet::get(FTy->getContext(),
                                               Attrs.getFnAttributes()));
  
        // The trampoline may have been bitcast to a bogus type (FTy).
        // Handle this by synthesizing a new function type, equal to FTy
        // with the chain parameter inserted.
  
        std::vector<Type*> NewTypes;
        NewTypes.reserve(FTy->getNumParams()+1);
  
        // Insert the chain's type into the list of parameter types, which may
        // mean appending it.
        {
          unsigned Idx = 1;
          FunctionType::param_iterator I = FTy->param_begin(),
            E = FTy->param_end();
  
          do {
            if (Idx == NestIdx)
              // Add the chain's type.
              NewTypes.push_back(NestTy);
  
            if (I == E)
              break;
  
            // Add the original type.
            NewTypes.push_back(*I);
  
            ++Idx;
            ++I;
          } while (1);
        }
  
        // Replace the trampoline call with a direct call.  Let the generic
        // code sort out any function type mismatches.
        FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
                                                  FTy->isVarArg());
        Constant *NewCallee =
          NestF->getType() == PointerType::getUnqual(NewFTy) ?
          NestF : ConstantExpr::getBitCast(NestF,
                                           PointerType::getUnqual(NewFTy));
        const AttributeSet &NewPAL =
            AttributeSet::get(FTy->getContext(), NewAttrs);
  
        SmallVector<OperandBundleDef, 1> OpBundles;
        CS.getOperandBundlesAsDefs(OpBundles);
  
        Instruction *NewCaller;
        if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
          NewCaller = InvokeInst::Create(NewCallee,
                                         II->getNormalDest(), II->getUnwindDest(),
                                         NewArgs, OpBundles);
          cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
          cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
        } else {
          NewCaller = CallInst::Create(NewCallee, NewArgs, OpBundles);
          if (cast<CallInst>(Caller)->isTailCall())
            cast<CallInst>(NewCaller)->setTailCall();
          cast<CallInst>(NewCaller)->
            setCallingConv(cast<CallInst>(Caller)->getCallingConv());
          cast<CallInst>(NewCaller)->setAttributes(NewPAL);
        }
  
        return NewCaller;
      }
    }
  
    // Replace the trampoline call with a direct call.  Since there is no 'nest'
    // parameter, there is no need to adjust the argument list.  Let the generic
    // code sort out any function type mismatches.
    Constant *NewCallee =
      NestF->getType() == PTy ? NestF :
                                ConstantExpr::getBitCast(NestF, PTy);
    CS.setCalledFunction(NewCallee);
    return CS.getInstruction();
  }
  