text: //===- InstCombineCalls.cpp -----------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This file implements the visitCall, visitInvoke, and visitCallBr functions.
  //
  //===----------------------------------------------------------------------===//
  
  #include "InstCombineInternal.h"
  #include "llvm/ADT/APFloat.h"
  #include "llvm/ADT/APInt.h"
  #include "llvm/ADT/APSInt.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/FloatingPointMode.h"
  #include "llvm/ADT/None.h"
  #include "llvm/ADT/Optional.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallBitVector.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/Statistic.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/Analysis/AliasAnalysis.h"
  #include "llvm/Analysis/AssumeBundleQueries.h"
  #include "llvm/Analysis/AssumptionCache.h"
  #include "llvm/Analysis/InstructionSimplify.h"
  #include "llvm/Analysis/Loads.h"
  #include "llvm/Analysis/MemoryBuiltins.h"
  #include "llvm/Analysis/TargetTransformInfo.h"
  #include "llvm/Analysis/ValueTracking.h"
  #include "llvm/Analysis/VectorUtils.h"
  #include "llvm/IR/Attributes.h"
  #include "llvm/IR/BasicBlock.h"
  #include "llvm/IR/Constant.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Function.h"
  #include "llvm/IR/GlobalVariable.h"
  #include "llvm/IR/InlineAsm.h"
  #include "llvm/IR/InstrTypes.h"
  #include "llvm/IR/Instruction.h"
  #include "llvm/IR/Instructions.h"
  #include "llvm/IR/IntrinsicInst.h"
  #include "llvm/IR/Intrinsics.h"
  #include "llvm/IR/IntrinsicsAArch64.h"
  #include "llvm/IR/IntrinsicsAMDGPU.h"
  #include "llvm/IR/IntrinsicsARM.h"
  #include "llvm/IR/IntrinsicsHexagon.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Metadata.h"
  #include "llvm/IR/PatternMatch.h"
  #include "llvm/IR/Statepoint.h"
  #include "llvm/IR/Type.h"
  #include "llvm/IR/User.h"
  #include "llvm/IR/Value.h"
  #include "llvm/IR/ValueHandle.h"
  #include "llvm/Support/AtomicOrdering.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/KnownBits.h"
  #include "llvm/Support/MathExtras.h"
  #include "llvm/Support/raw_ostream.h"
  #include "llvm/Transforms/InstCombine/InstCombiner.h"
  #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
  #include "llvm/Transforms/Utils/Local.h"
  #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
  #include <algorithm>
  #include <cassert>
  #include <cstdint>
  #include <cstring>
  #include <utility>
  #include <vector>
  
  #define DEBUG_TYPE "instcombine"
  #include "llvm/Transforms/Utils/InstructionWorklist.h"
  
  using namespace llvm;
  using namespace PatternMatch;
  
  STATISTIC(NumSimplified, "Number of library calls simplified");
  
  static cl::opt<unsigned> GuardWideningWindow(
      "instcombine-guard-widening-window",
      cl::init(3),
      cl::desc("How wide an instruction window to bypass looking for "
               "another guard"));
  
  namespace llvm {
  /// enable preservation of attributes in assume like:
  /// call void @llvm.assume(i1 true) [ "nonnull"(i32* %PTR) ]
  extern cl::opt<bool> EnableKnowledgeRetention;
  } // namespace llvm
  
  /// 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;
  }
  
  Instruction *InstCombinerImpl::SimplifyAnyMemTransfer(AnyMemTransferInst *MI) {
    Align DstAlign = getKnownAlignment(MI->getRawDest(), DL, MI, &AC, &DT);
    MaybeAlign CopyDstAlign = MI->getDestAlign();
    if (!CopyDstAlign || *CopyDstAlign < DstAlign) {
      MI->setDestAlignment(DstAlign);
      return MI;
    }
  
    Align SrcAlign = getKnownAlignment(MI->getRawSource(), DL, MI, &AC, &DT);
    MaybeAlign CopySrcAlign = MI->getSourceAlign();
    if (!CopySrcAlign || *CopySrcAlign < SrcAlign) {
      MI->setSourceAlignment(SrcAlign);
      return MI;
    }
  
    // If we have a store to a location which is known constant, we can conclude
    // that the store must be storing the constant value (else the memory
    // wouldn't be constant), and this must be a noop.
    if (AA->pointsToConstantMemory(MI->getDest())) {
      // Set the size of the copy to 0, it will be deleted on the next iteration.
      MI->setLength(Constant::getNullValue(MI->getLength()->getType()));
      return MI;
    }
  
    // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
    // load/store.
    ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getLength());
    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.
  
    // If it is an atomic and alignment is less than the size then we will
    // introduce the unaligned memory access which will be later transformed
    // into libcall in CodeGen. This is not evident performance gain so disable
    // it now.
    if (isa<AtomicMemTransferInst>(MI))
      if (*CopyDstAlign < Size || *CopySrcAlign < Size)
        return nullptr;
  
    // 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);
  
    // If the memcpy has metadata describing the members, see if we can get the
    // TBAA tag describing our copy.
    MDNode *CopyMD = nullptr;
    if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa)) {
      CopyMD = M;
    } else 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))->isZero() &&
          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));
    }
  
    Value *Src = Builder.CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy);
    Value *Dest = Builder.CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
    LoadInst *L = Builder.CreateLoad(IntType, Src);
    // Alignment from the mem intrinsic will be better, so use it.
    L->setAlignment(*CopySrcAlign);
    if (CopyMD)
      L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
    MDNode *LoopMemParallelMD =
      MI->getMetadata(LLVMContext::MD_mem_parallel_loop_access);
    if (LoopMemParallelMD)
      L->setMetadata(LLVMContext::MD_mem_parallel_loop_access, LoopMemParallelMD);
    MDNode *AccessGroupMD = MI->getMetadata(LLVMContext::MD_access_group);
    if (AccessGroupMD)
      L->setMetadata(LLVMContext::MD_access_group, AccessGroupMD);
  
    StoreInst *S = Builder.CreateStore(L, Dest);
    // Alignment from the mem intrinsic will be better, so use it.
    S->setAlignment(*CopyDstAlign);
    if (CopyMD)
      S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
    if (LoopMemParallelMD)
      S->setMetadata(LLVMContext::MD_mem_parallel_loop_access, LoopMemParallelMD);
    if (AccessGroupMD)
      S->setMetadata(LLVMContext::MD_access_group, AccessGroupMD);
  
    if (auto *MT = dyn_cast<MemTransferInst>(MI)) {
      // non-atomics can be volatile
      L->setVolatile(MT->isVolatile());
      S->setVolatile(MT->isVolatile());
    }
    if (isa<AtomicMemTransferInst>(MI)) {
      // atomics have to be unordered
      L->setOrdering(AtomicOrdering::Unordered);
      S->setOrdering(AtomicOrdering::Unordered);
    }
  
    // Set the size of the copy to 0, it will be deleted on the next iteration.
    MI->setLength(Constant::getNullValue(MemOpLength->getType()));
    return MI;
  }
  
  Instruction *InstCombinerImpl::SimplifyAnyMemSet(AnyMemSetInst *MI) {
    const Align KnownAlignment =
        getKnownAlignment(MI->getDest(), DL, MI, &AC, &DT);
    MaybeAlign MemSetAlign = MI->getDestAlign();
    if (!MemSetAlign || *MemSetAlign < KnownAlignment) {
      MI->setDestAlignment(KnownAlignment);
      return MI;
    }
  
    // If we have a store to a location which is known constant, we can conclude
    // that the store must be storing the constant value (else the memory
    // wouldn't be constant), and this must be a noop.
    if (AA->pointsToConstantMemory(MI->getDest())) {
      // Set the size of the copy to 0, it will be deleted on the next iteration.
      MI->setLength(Constant::getNullValue(MI->getLength()->getType()));
      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;
    const uint64_t Len = LenC->getLimitedValue();
    assert(Len && "0-sized memory setting should be removed already.");
    const Align Alignment = assumeAligned(MI->getDestAlignment());
  
    // If it is an atomic and alignment is less than the size then we will
    // introduce the unaligned memory access which will be later transformed
    // into libcall in CodeGen. This is not evident performance gain so disable
    // it now.
    if (isa<AtomicMemSetInst>(MI))
      if (Alignment < Len)
        return nullptr;
  
    // 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);
  
      // 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);
      if (isa<AtomicMemSetInst>(MI))
        S->setOrdering(AtomicOrdering::Unordered);
  
      // 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;
  }
  
  // TODO, Obvious Missing Transforms:
  // * Narrow width by halfs excluding zero/undef lanes
  Value *InstCombinerImpl::simplifyMaskedLoad(IntrinsicInst &II) {
    Value *LoadPtr = II.getArgOperand(0);
    const Align Alignment =
        cast<ConstantInt>(II.getArgOperand(1))->getAlignValue();
  
    // If the mask is all ones or undefs, this is a plain vector load of the 1st
    // argument.
    if (maskIsAllOneOrUndef(II.getArgOperand(2))) {
      LoadInst *L = Builder.CreateAlignedLoad(II.getType(), LoadPtr, Alignment,
                                              "unmaskedload");
      L->copyMetadata(II);
      return L;
    }
  
    // If we can unconditionally load from this address, replace with a
    // load/select idiom. TODO: use DT for context sensitive query
    if (isDereferenceablePointer(LoadPtr, II.getType(),
                                 II.getModule()->getDataLayout(), &II, nullptr)) {
      LoadInst *LI = Builder.CreateAlignedLoad(II.getType(), LoadPtr, Alignment,
                                               "unmaskedload");
      LI->copyMetadata(II);
      return Builder.CreateSelect(II.getArgOperand(2), LI, II.getArgOperand(3));
    }
  
    return nullptr;
  }
  
  // TODO, Obvious Missing Transforms:
  // * Single constant active lane -> store
  // * Narrow width by halfs excluding zero/undef lanes
  Instruction *InstCombinerImpl::simplifyMaskedStore(IntrinsicInst &II) {
    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 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);
      Align Alignment = cast<ConstantInt>(II.getArgOperand(2))->getAlignValue();
      StoreInst *S =
          new StoreInst(II.getArgOperand(0), StorePtr, false, Alignment);
      S->copyMetadata(II);
      return S;
    }
  
    if (isa<ScalableVectorType>(ConstMask->getType()))
      return nullptr;
  
    // Use masked off lanes to simplify operands via SimplifyDemandedVectorElts
    APInt DemandedElts = possiblyDemandedEltsInMask(ConstMask);
    APInt UndefElts(DemandedElts.getBitWidth(), 0);
    if (Value *V =
            SimplifyDemandedVectorElts(II.getOperand(0), DemandedElts, UndefElts))
      return replaceOperand(II, 0, V);
  
    return nullptr;
  }
  
  // TODO, Obvious Missing Transforms:
  // * Single constant active lane load -> load
  // * Dereferenceable address & few lanes -> scalarize speculative load/selects
  // * Adjacent vector addresses -> masked.load
  // * Narrow width by halfs excluding zero/undef lanes
  // * Vector incrementing address -> vector masked load
  Instruction *InstCombinerImpl::simplifyMaskedGather(IntrinsicInst &II) {
    auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(2));
    if (!ConstMask)
      return nullptr;
  
    // Vector splat address w/known mask -> scalar load
    // Fold the gather to load the source vector first lane
    // because it is reloading the same value each time
    if (ConstMask->isAllOnesValue())
      if (auto *SplatPtr = getSplatValue(II.getArgOperand(0))) {
        auto *VecTy = cast<VectorType>(II.getType());
        const Align Alignment =
            cast<ConstantInt>(II.getArgOperand(1))->getAlignValue();
        LoadInst *L = Builder.CreateAlignedLoad(VecTy->getElementType(), SplatPtr,
                                                Alignment, "load.scalar");
        Value *Shuf =
            Builder.CreateVectorSplat(VecTy->getElementCount(), L, "broadcast");
        return replaceInstUsesWith(II, cast<Instruction>(Shuf));
      }
  
    return nullptr;
  }
  
  // TODO, Obvious Missing Transforms:
  // * Single constant active lane -> store
  // * Adjacent vector addresses -> masked.store
  // * Narrow store width by halfs excluding zero/undef lanes
  // * Vector incrementing address -> vector masked store
  Instruction *InstCombinerImpl::simplifyMaskedScatter(IntrinsicInst &II) {
    auto *ConstMask = dyn_cast<Constant>(II.getArgOperand(3));
    if (!ConstMask)
      return nullptr;
  
    // If the mask is all zeros, a scatter does nothing.
    if (ConstMask->isNullValue())
      return eraseInstFromFunction(II);
  
    // Vector splat address -> scalar store
    if (auto *SplatPtr = getSplatValue(II.getArgOperand(1))) {
      // scatter(splat(value), splat(ptr), non-zero-mask) -> store value, ptr
      if (auto *SplatValue = getSplatValue(II.getArgOperand(0))) {
        Align Alignment = cast<ConstantInt>(II.getArgOperand(2))->getAlignValue();
        StoreInst *S =
            new StoreInst(SplatValue, SplatPtr, /*IsVolatile=*/false, Alignment);
        S->copyMetadata(II);
        return S;
      }
      // scatter(vector, splat(ptr), splat(true)) -> store extract(vector,
      // lastlane), ptr
      if (ConstMask->isAllOnesValue()) {
        Align Alignment = cast<ConstantInt>(II.getArgOperand(2))->getAlignValue();
        VectorType *WideLoadTy = cast<VectorType>(II.getArgOperand(1)->getType());
        ElementCount VF = WideLoadTy->getElementCount();
        Constant *EC =
            ConstantInt::get(Builder.getInt32Ty(), VF.getKnownMinValue());
        Value *RunTimeVF = VF.isScalable() ? Builder.CreateVScale(EC) : EC;
        Value *LastLane = Builder.CreateSub(RunTimeVF, Builder.getInt32(1));
        Value *Extract =
            Builder.CreateExtractElement(II.getArgOperand(0), LastLane);
        StoreInst *S =
            new StoreInst(Extract, SplatPtr, /*IsVolatile=*/false, Alignment);
        S->copyMetadata(II);
        return S;
      }
    }
    if (isa<ScalableVectorType>(ConstMask->getType()))
      return nullptr;
  
    // Use masked off lanes to simplify operands via SimplifyDemandedVectorElts
    APInt DemandedElts = possiblyDemandedEltsInMask(ConstMask);
    APInt UndefElts(DemandedElts.getBitWidth(), 0);
    if (Value *V =
            SimplifyDemandedVectorElts(II.getOperand(0), DemandedElts, UndefElts))
      return replaceOperand(II, 0, V);
    if (Value *V =
            SimplifyDemandedVectorElts(II.getOperand(1), DemandedElts, UndefElts))
      return replaceOperand(II, 1, V);
  
    return nullptr;
  }
  
  /// This function transforms launder.invariant.group and strip.invariant.group
  /// like:
  /// launder(launder(%x)) -> launder(%x)       (the result is not the argument)
  /// launder(strip(%x)) -> launder(%x)
  /// strip(strip(%x)) -> strip(%x)             (the result is not the argument)
  /// strip(launder(%x)) -> strip(%x)
  /// This is legal because it preserves the most recent information about
  /// the presence or absence of invariant.group.
  static Instruction *simplifyInvariantGroupIntrinsic(IntrinsicInst &II,
                                                      InstCombinerImpl &IC) {
    auto *Arg = II.getArgOperand(0);
    auto *StrippedArg = Arg->stripPointerCasts();
    auto *StrippedInvariantGroupsArg = StrippedArg;
    while (auto *Intr = dyn_cast<IntrinsicInst>(StrippedInvariantGroupsArg)) {
      if (Intr->getIntrinsicID() != Intrinsic::launder_invariant_group &&
          Intr->getIntrinsicID() != Intrinsic::strip_invariant_group)
        break;
      StrippedInvariantGroupsArg = Intr->getArgOperand(0)->stripPointerCasts();
    }
    if (StrippedArg == StrippedInvariantGroupsArg)
      return nullptr; // No launders/strips to remove.
  
    Value *Result = nullptr;
  
    if (II.getIntrinsicID() == Intrinsic::launder_invariant_group)
      Result = IC.Builder.CreateLaunderInvariantGroup(StrippedInvariantGroupsArg);
    else if (II.getIntrinsicID() == Intrinsic::strip_invariant_group)
      Result = IC.Builder.CreateStripInvariantGroup(StrippedInvariantGroupsArg);
    else
      llvm_unreachable(
          "simplifyInvariantGroupIntrinsic only handles launder and strip");
    if (Result->getType()->getPointerAddressSpace() !=
        II.getType()->getPointerAddressSpace())
      Result = IC.Builder.CreateAddrSpaceCast(Result, II.getType());
    if (Result->getType() != II.getType())
      Result = IC.Builder.CreateBitCast(Result, II.getType());
  
    return cast<Instruction>(Result);
  }
  
  static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombinerImpl &IC) {
    assert((II.getIntrinsicID() == Intrinsic::cttz ||
            II.getIntrinsicID() == Intrinsic::ctlz) &&
           "Expected cttz or ctlz intrinsic");
    bool IsTZ = II.getIntrinsicID() == Intrinsic::cttz;
    Value *Op0 = II.getArgOperand(0);
    Value *Op1 = II.getArgOperand(1);
    Value *X;
    // ctlz(bitreverse(x)) -> cttz(x)
    // cttz(bitreverse(x)) -> ctlz(x)
    if (match(Op0, m_BitReverse(m_Value(X)))) {
      Intrinsic::ID ID = IsTZ ? Intrinsic::ctlz : Intrinsic::cttz;
      Function *F = Intrinsic::getDeclaration(II.getModule(), ID, II.getType());
      return CallInst::Create(F, {X, II.getArgOperand(1)});
    }
  
    if (II.getType()->isIntOrIntVectorTy(1)) {
      // ctlz/cttz i1 Op0 --> not Op0
      if (match(Op1, m_Zero()))
        return BinaryOperator::CreateNot(Op0);
      // If zero is poison, then the input can be assumed to be "true", so the
      // instruction simplifies to "false".
      assert(match(Op1, m_One()) && "Expected ctlz/cttz operand to be 0 or 1");
      return IC.replaceInstUsesWith(II, ConstantInt::getNullValue(II.getType()));
    }
  
    // If the operand is a select with constant arm(s), try to hoist ctlz/cttz.
    if (auto *Sel = dyn_cast<SelectInst>(Op0))
      if (Instruction *R = IC.FoldOpIntoSelect(II, Sel))
        return R;
  
    if (IsTZ) {
      // cttz(-x) -> cttz(x)
      if (match(Op0, m_Neg(m_Value(X))))
        return IC.replaceOperand(II, 0, X);
  
      // cttz(sext(x)) -> cttz(zext(x))
      if (match(Op0, m_OneUse(m_SExt(m_Value(X))))) {
        auto *Zext = IC.Builder.CreateZExt(X, II.getType());
        auto *CttzZext =
            IC.Builder.CreateBinaryIntrinsic(Intrinsic::cttz, Zext, Op1);
        return IC.replaceInstUsesWith(II, CttzZext);
      }
  
      // Zext doesn't change the number of trailing zeros, so narrow:
      // cttz(zext(x)) -> zext(cttz(x)) if the 'ZeroIsPoison' parameter is 'true'.
      if (match(Op0, m_OneUse(m_ZExt(m_Value(X)))) && match(Op1, m_One())) {
        auto *Cttz = IC.Builder.CreateBinaryIntrinsic(Intrinsic::cttz, X,
                                                      IC.Builder.getTrue());
        auto *ZextCttz = IC.Builder.CreateZExt(Cttz, II.getType());
        return IC.replaceInstUsesWith(II, ZextCttz);
      }
  
      // cttz(abs(x)) -> cttz(x)
      // cttz(nabs(x)) -> cttz(x)
      Value *Y;
      SelectPatternFlavor SPF = matchSelectPattern(Op0, X, Y).Flavor;
      if (SPF == SPF_ABS || SPF == SPF_NABS)
        return IC.replaceOperand(II, 0, X);
  
      if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(X))))
        return IC.replaceOperand(II, 0, X);
    }
  
    KnownBits Known = IC.computeKnownBits(Op0, 0, &II);
  
    // Create a mask for bits above (ctlz) or below (cttz) the first known one.
    unsigned PossibleZeros = IsTZ ? Known.countMaxTrailingZeros()
                                  : Known.countMaxLeadingZeros();
    unsigned DefiniteZeros = IsTZ ? Known.countMinTrailingZeros()
                                  : Known.countMinLeadingZeros();
  
    // If all bits above (ctlz) or below (cttz) the first known one are known
    // zero, this value is constant.
    // FIXME: This should be in InstSimplify because we're replacing an
    // instruction with a constant.
    if (PossibleZeros == DefiniteZeros) {
      auto *C = ConstantInt::get(Op0->getType(), DefiniteZeros);
      return IC.replaceInstUsesWith(II, C);
    }
  
    // If the input to cttz/ctlz is known to be non-zero,
    // then change the 'ZeroIsPoison' parameter to 'true'
    // because we know the zero behavior can't affect the result.
    if (!Known.One.isZero() ||
        isKnownNonZero(Op0, IC.getDataLayout(), 0, &IC.getAssumptionCache(), &II,
                       &IC.getDominatorTree())) {
      if (!match(II.getArgOperand(1), m_One()))
        return IC.replaceOperand(II, 1, IC.Builder.getTrue());
    }
  
    // Add range metadata since known bits can't completely reflect what we know.
    // TODO: Handle splat vectors.
    auto *IT = dyn_cast<IntegerType>(Op0->getType());
    if (IT && IT->getBitWidth() != 1 && !II.getMetadata(LLVMContext::MD_range)) {
      Metadata *LowAndHigh[] = {
          ConstantAsMetadata::get(ConstantInt::get(IT, DefiniteZeros)),
          ConstantAsMetadata::get(ConstantInt::get(IT, PossibleZeros + 1))};
      II.setMetadata(LLVMContext::MD_range,
                     MDNode::get(II.getContext(), LowAndHigh));
      return &II;
    }
  
    return nullptr;
  }
  
  static Instruction *foldCtpop(IntrinsicInst &II, InstCombinerImpl &IC) {
    assert(II.getIntrinsicID() == Intrinsic::ctpop &&
           "Expected ctpop intrinsic");
    Type *Ty = II.getType();
    unsigned BitWidth = Ty->getScalarSizeInBits();
    Value *Op0 = II.getArgOperand(0);
    Value *X, *Y;
  
    // ctpop(bitreverse(x)) -> ctpop(x)
    // ctpop(bswap(x)) -> ctpop(x)
    if (match(Op0, m_BitReverse(m_Value(X))) || match(Op0, m_BSwap(m_Value(X))))
      return IC.replaceOperand(II, 0, X);
  
    // ctpop(rot(x)) -> ctpop(x)
    if ((match(Op0, m_FShl(m_Value(X), m_Value(Y), m_Value())) ||
         match(Op0, m_FShr(m_Value(X), m_Value(Y), m_Value()))) &&
        X == Y)
      return IC.replaceOperand(II, 0, X);
  
    // ctpop(x | -x) -> bitwidth - cttz(x, false)
    if (Op0->hasOneUse() &&
        match(Op0, m_c_Or(m_Value(X), m_Neg(m_Deferred(X))))) {
      Function *F =
          Intrinsic::getDeclaration(II.getModule(), Intrinsic::cttz, Ty);
      auto *Cttz = IC.Builder.CreateCall(F, {X, IC.Builder.getFalse()});
      auto *Bw = ConstantInt::get(Ty, APInt(BitWidth, BitWidth));
      return IC.replaceInstUsesWith(II, IC.Builder.CreateSub(Bw, Cttz));
    }
  
    // ctpop(~x & (x - 1)) -> cttz(x, false)
    if (match(Op0,
              m_c_And(m_Not(m_Value(X)), m_Add(m_Deferred(X), m_AllOnes())))) {
      Function *F =
          Intrinsic::getDeclaration(II.getModule(), Intrinsic::cttz, Ty);
      return CallInst::Create(F, {X, IC.Builder.getFalse()});
    }
  
    // Zext doesn't change the number of set bits, so narrow:
    // ctpop (zext X) --> zext (ctpop X)
    if (match(Op0, m_OneUse(m_ZExt(m_Value(X))))) {
      Value *NarrowPop = IC.Builder.CreateUnaryIntrinsic(Intrinsic::ctpop, X);
      return CastInst::Create(Instruction::ZExt, NarrowPop, Ty);
    }
  
    // If the operand is a select with constant arm(s), try to hoist ctpop.
    if (auto *Sel = dyn_cast<SelectInst>(Op0))
      if (Instruction *R = IC.FoldOpIntoSelect(II, Sel))
        return R;
  
    KnownBits Known(BitWidth);
    IC.computeKnownBits(Op0, Known, 0, &II);
  
    // If all bits are zero except for exactly one fixed bit, then the result
    // must be 0 or 1, and we can get that answer by shifting to LSB:
    // ctpop (X & 32) --> (X & 32) >> 5
    if ((~Known.Zero).isPowerOf2())
      return BinaryOperator::CreateLShr(
          Op0, ConstantInt::get(Ty, (~Known.Zero).exactLogBase2()));
  
    // FIXME: Try to simplify vectors of integers.
    auto *IT = dyn_cast<IntegerType>(Ty);
    if (!IT)
      return nullptr;
  
    // Add range metadata since known bits can't completely reflect what we know.
    unsigned MinCount = Known.countMinPopulation();
    unsigned MaxCount = Known.countMaxPopulation();
    if (IT->getBitWidth() != 1 && !II.getMetadata(LLVMContext::MD_range)) {
      Metadata *LowAndHigh[] = {
          ConstantAsMetadata::get(ConstantInt::get(IT, MinCount)),
          ConstantAsMetadata::get(ConstantInt::get(IT, MaxCount + 1))};
      II.setMetadata(LLVMContext::MD_range,
                     MDNode::get(II.getContext(), LowAndHigh));
      return &II;
    }
  
    return nullptr;
  }
  
  /// Convert a table lookup to shufflevector if the mask is constant.
  /// This could benefit tbl1 if the mask is { 7,6,5,4,3,2,1,0 }, in
  /// which case we could lower the shufflevector with rev64 instructions
  /// as it's actually a byte reverse.
  static Value *simplifyNeonTbl1(const IntrinsicInst &II,
                                 InstCombiner::BuilderTy &Builder) {
    // Bail out if the mask is not a constant.
    auto *C = dyn_cast<Constant>(II.getArgOperand(1));
    if (!C)
      return nullptr;
  
    auto *VecTy = cast<FixedVectorType>(II.getType());
    unsigned NumElts = VecTy->getNumElements();
  
    // Only perform this transformation for <8 x i8> vector types.
    if (!VecTy->getElementType()->isIntegerTy(8) || NumElts != 8)
      return nullptr;
  
    int Indexes[8];
  
    for (unsigned I = 0; I < NumElts; ++I) {
      Constant *COp = C->getAggregateElement(I);
  
      if (!COp || !isa<ConstantInt>(COp))
        return nullptr;
  
      Indexes[I] = cast<ConstantInt>(COp)->getLimitedValue();
  
      // Make sure the mask indices are in range.
      if ((unsigned)Indexes[I] >= NumElts)
        return nullptr;
    }
  
    auto *V1 = II.getArgOperand(0);
    auto *V2 = Constant::getNullValue(V1->getType());
    return Builder.CreateShuffleVector(V1, V2, makeArrayRef(Indexes));
  }
  
  // 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.arg_size() >= NumOperands && "Not enough operands");
    assert(E.arg_size() >= 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)
  //   call @llvm.foo.start(i1 0) ; This one won't be skipped: it will be removed
  //   call @llvm.foo.end(i1 0)
  //   call @llvm.foo.end(i1 0) ; &I
  static bool
  removeTriviallyEmptyRange(IntrinsicInst &EndI, InstCombinerImpl &IC,
                            std::function<bool(const IntrinsicInst &)> IsStart) {
    // We start from the end intrinsic and scan backwards, so that InstCombine
    // has already processed (and potentially removed) all the instructions
    // before the end intrinsic.
    BasicBlock::reverse_iterator BI(EndI), BE(EndI.getParent()->rend());
    for (; BI != BE; ++BI) {
      if (auto *I = dyn_cast<IntrinsicInst>(&*BI)) {
        if (I->isDebugOrPseudoInst() ||
            I->getIntrinsicID() == EndI.getIntrinsicID())
          continue;
        if (IsStart(*I)) {
          if (haveSameOperands(EndI, *I, EndI.arg_size())) {
            IC.eraseInstFromFunction(*I);
            IC.eraseInstFromFunction(EndI);
            return true;
          }
          // Skip start intrinsics that don't pair with this end intrinsic.
          continue;
        }
      }
      break;
    }
  
    return false;
  }
  
  Instruction *InstCombinerImpl::visitVAEndInst(VAEndInst &I) {
    removeTriviallyEmptyRange(I, *this, [](const IntrinsicInst &I) {
      return I.getIntrinsicID() == Intrinsic::vastart ||
             I.getIntrinsicID() == Intrinsic::vacopy;
    });
    return nullptr;
  }
  
  static CallInst *canonicalizeConstantArg0ToArg1(CallInst &Call) {
    assert(Call.arg_size() > 1 && "Need at least 2 args to swap");
    Value *Arg0 = Call.getArgOperand(0), *Arg1 = Call.getArgOperand(1);
    if (isa<Constant>(Arg0) && !isa<Constant>(Arg1)) {
      Call.setArgOperand(0, Arg1);
      Call.setArgOperand(1, Arg0);
      return &Call;
    }
    return nullptr;
  }
  
  /// Creates a result tuple for an overflow intrinsic \p II with a given
  /// \p Result and a constant \p Overflow value.
  static Instruction *createOverflowTuple(IntrinsicInst *II, Value *Result,
                                          Constant *Overflow) {
    Constant *V[] = {UndefValue::get(Result->getType()), Overflow};
    StructType *ST = cast<StructType>(II->getType());
    Constant *Struct = ConstantStruct::get(ST, V);
    return InsertValueInst::Create(Struct, Result, 0);
  }
  
  Instruction *
  InstCombinerImpl::foldIntrinsicWithOverflowCommon(IntrinsicInst *II) {
    WithOverflowInst *WO = cast<WithOverflowInst>(II);
    Value *OperationResult = nullptr;
    Constant *OverflowResult = nullptr;
    if (OptimizeOverflowCheck(WO->getBinaryOp(), WO->isSigned(), WO->getLHS(),
                              WO->getRHS(), *WO, OperationResult, OverflowResult))
      return createOverflowTuple(WO, OperationResult, OverflowResult);
    return nullptr;
  }
  
  static Optional<bool> getKnownSign(Value *Op, Instruction *CxtI,
                                     const DataLayout &DL, AssumptionCache *AC,
                                     DominatorTree *DT) {
    KnownBits Known = computeKnownBits(Op, DL, 0, AC, CxtI, DT);
    if (Known.isNonNegative())
      return false;
    if (Known.isNegative())
      return true;
  
    return isImpliedByDomCondition(
        ICmpInst::ICMP_SLT, Op, Constant::getNullValue(Op->getType()), CxtI, DL);
  }
  
  /// Try to canonicalize min/max(X + C0, C1) as min/max(X, C1 - C0) + C0. This
  /// can trigger other combines.
  static Instruction *moveAddAfterMinMax(IntrinsicInst *II,
                                         InstCombiner::BuilderTy &Builder) {
    Intrinsic::ID MinMaxID = II->getIntrinsicID();
    assert((MinMaxID == Intrinsic::smax || MinMaxID == Intrinsic::smin ||
            MinMaxID == Intrinsic::umax || MinMaxID == Intrinsic::umin) &&
           "Expected a min or max intrinsic");
  
    // TODO: Match vectors with undef elements, but undef may not propagate.
    Value *Op0 = II->getArgOperand(0), *Op1 = II->getArgOperand(1);
    Value *X;
    const APInt *C0, *C1;
    if (!match(Op0, m_OneUse(m_Add(m_Value(X), m_APInt(C0)))) ||
        !match(Op1, m_APInt(C1)))
      return nullptr;
  
    // Check for necessary no-wrap and overflow constraints.
    bool IsSigned = MinMaxID == Intrinsic::smax || MinMaxID == Intrinsic::smin;
    auto *Add = cast<BinaryOperator>(Op0);
    if ((IsSigned && !Add->hasNoSignedWrap()) ||
        (!IsSigned && !Add->hasNoUnsignedWrap()))
      return nullptr;
  
    // If the constant difference overflows, then instsimplify should reduce the
    // min/max to the add or C1.
    bool Overflow;
    APInt CDiff =
        IsSigned ? C1->ssub_ov(*C0, Overflow) : C1->usub_ov(*C0, Overflow);
    assert(!Overflow && "Expected simplify of min/max");
  
    // min/max (add X, C0), C1 --> add (min/max X, C1 - C0), C0
    // Note: the "mismatched" no-overflow setting does not propagate.
    Constant *NewMinMaxC = ConstantInt::get(II->getType(), CDiff);
    Value *NewMinMax = Builder.CreateBinaryIntrinsic(MinMaxID, X, NewMinMaxC);
    return IsSigned ? BinaryOperator::CreateNSWAdd(NewMinMax, Add->getOperand(1))
                    : BinaryOperator::CreateNUWAdd(NewMinMax, Add->getOperand(1));
  }
  
  /// If we have a clamp pattern like max (min X, 42), 41 -- where the output
  /// can only be one of two possible constant values -- turn that into a select
  /// of constants.
  static Instruction *foldClampRangeOfTwo(IntrinsicInst *II,
                                          InstCombiner::BuilderTy &Builder) {
    Value *I0 = II->getArgOperand(0), *I1 = II->getArgOperand(1);
    Value *X;
    const APInt *C0, *C1;
    if (!match(I1, m_APInt(C1)) || !I0->hasOneUse())
      return nullptr;
  
    CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
    switch (II->getIntrinsicID()) {
    case Intrinsic::smax:
      if (match(I0, m_SMin(m_Value(X), m_APInt(C0))) && *C0 == *C1 + 1)
        Pred = ICmpInst::ICMP_SGT;
      break;
    case Intrinsic::smin:
      if (match(I0, m_SMax(m_Value(X), m_APInt(C0))) && *C1 == *C0 + 1)
        Pred = ICmpInst::ICMP_SLT;
      break;
    case Intrinsic::umax:
      if (match(I0, m_UMin(m_Value(X), m_APInt(C0))) && *C0 == *C1 + 1)
        Pred = ICmpInst::ICMP_UGT;
      break;
    case Intrinsic::umin:
      if (match(I0, m_UMax(m_Value(X), m_APInt(C0))) && *C1 == *C0 + 1)
        Pred = ICmpInst::ICMP_ULT;
      break;
    default:
      llvm_unreachable("Expected min/max intrinsic");
    }
    if (Pred == CmpInst::BAD_ICMP_PREDICATE)
      return nullptr;
  
    // max (min X, 42), 41 --> X > 41 ? 42 : 41
    // min (max X, 42), 43 --> X < 43 ? 42 : 43
    Value *Cmp = Builder.CreateICmp(Pred, X, I1);
    return SelectInst::Create(Cmp, ConstantInt::get(II->getType(), *C0), I1);
  }
  
  /// If this min/max has a constant operand and an operand that is a matching
  /// min/max with a constant operand, constant-fold the 2 constant operands.
  static Instruction *reassociateMinMaxWithConstants(IntrinsicInst *II) {
    Intrinsic::ID MinMaxID = II->getIntrinsicID();
    auto *LHS = dyn_cast<IntrinsicInst>(II->getArgOperand(0));
    if (!LHS || LHS->getIntrinsicID() != MinMaxID)
      return nullptr;
  
    Constant *C0, *C1;
    if (!match(LHS->getArgOperand(1), m_ImmConstant(C0)) ||
        !match(II->getArgOperand(1), m_ImmConstant(C1)))
      return nullptr;
  
    // max (max X, C0), C1 --> max X, (max C0, C1) --> max X, NewC
    ICmpInst::Predicate Pred = MinMaxIntrinsic::getPredicate(MinMaxID);
    Constant *CondC = ConstantExpr::getICmp(Pred, C0, C1);
    Constant *NewC = ConstantExpr::getSelect(CondC, C0, C1);
  
    Module *Mod = II->getModule();
    Function *MinMax = Intrinsic::getDeclaration(Mod, MinMaxID, II->getType());
    return CallInst::Create(MinMax, {LHS->getArgOperand(0), NewC});
  }
  
  /// Reduce a sequence of min/max intrinsics with a common operand.
  static Instruction *factorizeMinMaxTree(IntrinsicInst *II) {
    // Match 3 of the same min/max ops. Example: umin(umin(), umin()).
    auto *LHS = dyn_cast<IntrinsicInst>(II->getArgOperand(0));
    auto *RHS = dyn_cast<IntrinsicInst>(II->getArgOperand(1));
    Intrinsic::ID MinMaxID = II->getIntrinsicID();
    if (!LHS || !RHS || LHS->getIntrinsicID() != MinMaxID ||
        RHS->getIntrinsicID() != MinMaxID ||
        (!LHS->hasOneUse() && !RHS->hasOneUse()))
      return nullptr;
  
    Value *A = LHS->getArgOperand(0);
    Value *B = LHS->getArgOperand(1);
    Value *C = RHS->getArgOperand(0);
    Value *D = RHS->getArgOperand(1);
  
    // Look for a common operand.
    Value *MinMaxOp = nullptr;
    Value *ThirdOp = nullptr;
    if (LHS->hasOneUse()) {
      // If the LHS is only used in this chain and the RHS is used outside of it,
      // reuse the RHS min/max because that will eliminate the LHS.
      if (D == A || C == A) {
        // min(min(a, b), min(c, a)) --> min(min(c, a), b)
        // min(min(a, b), min(a, d)) --> min(min(a, d), b)
        MinMaxOp = RHS;
        ThirdOp = B;
      } else if (D == B || C == B) {
        // min(min(a, b), min(c, b)) --> min(min(c, b), a)
        // min(min(a, b), min(b, d)) --> min(min(b, d), a)
        MinMaxOp = RHS;
        ThirdOp = A;
      }
    } else {
      assert(RHS->hasOneUse() && "Expected one-use operand");
      // Reuse the LHS. This will eliminate the RHS.
      if (D == A || D == B) {
        // min(min(a, b), min(c, a)) --> min(min(a, b), c)
        // min(min(a, b), min(c, b)) --> min(min(a, b), c)
        MinMaxOp = LHS;
        ThirdOp = C;
      } else if (C == A || C == B) {
        // min(min(a, b), min(b, d)) --> min(min(a, b), d)
        // min(min(a, b), min(c, b)) --> min(min(a, b), d)
        MinMaxOp = LHS;
        ThirdOp = D;
      }
    }
  
    if (!MinMaxOp || !ThirdOp)
      return nullptr;
  
    Module *Mod = II->getModule();
    Function *MinMax = Intrinsic::getDeclaration(Mod, MinMaxID, II->getType());
    return CallInst::Create(MinMax, { MinMaxOp, ThirdOp });
  }
  
  /// CallInst simplification. This mostly only handles folding of intrinsic
  /// instructions. For normal calls, it allows visitCallBase to do the heavy
  /// lifting.
  Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
    // Don't try to simplify calls without uses. It will not do anything useful,
    // but will result in the following folds being skipped.
    if (!CI.use_empty())
      if (Value *V = SimplifyCall(&CI, SQ.getWithInstruction(&CI)))
        return replaceInstUsesWith(CI, V);
  
    if (isFreeCall(&CI, &TLI))
      return visitFree(CI);
  
    // If the caller function (i.e. us, the function that contains this CallInst)
    // is nounwind, mark the call as nounwind, even if the callee isn't.
    if (CI.getFunction()->doesNotThrow() && !CI.doesNotThrow()) {
      CI.setDoesNotThrow();
      return &CI;
    }
  
    IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
    if (!II) return visitCallBase(CI);
  
    // For atomic unordered mem intrinsics if len is not a positive or
    // not a multiple of element size then behavior is undefined.
    if (auto *AMI = dyn_cast<AtomicMemIntrinsic>(II))
      if (ConstantInt *NumBytes = dyn_cast<ConstantInt>(AMI->getLength()))
        if (NumBytes->getSExtValue() < 0 ||
            (NumBytes->getZExtValue() % AMI->getElementSizeInBytes() != 0)) {
          CreateNonTerminatorUnreachable(AMI);
          assert(AMI->getType()->isVoidTy() &&
                 "non void atomic unordered mem intrinsic");
          return eraseInstFromFunction(*AMI);
        }
  
    // Intrinsics cannot occur in an invoke or a callbr, so handle them here
    // instead of in visitCallBase.
    if (auto *MI = dyn_cast<AnyMemIntrinsic>(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 (auto *M = dyn_cast<MemIntrinsic>(MI))
        if (M->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 (auto *MMI = dyn_cast<AnyMemMoveInst>(MI)) {
        if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
          if (GVSrc->isConstant()) {
            Module *M = CI.getModule();
            Intrinsic::ID MemCpyID =
                isa<AtomicMemMoveInst>(MMI)
                    ? Intrinsic::memcpy_element_unordered_atomic
                    : 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 (AnyMemTransferInst *MTI = dyn_cast<AnyMemTransferInst>(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 (auto *MTI = dyn_cast<AnyMemTransferInst>(MI)) {
        if (Instruction *I = SimplifyAnyMemTransfer(MTI))
          return I;
      } else if (auto *MSI = dyn_cast<AnyMemSetInst>(MI)) {
        if (Instruction *I = SimplifyAnyMemSet(MSI))
          return I;
      }
  
      if (Changed) return II;
    }
  
    // For fixed width vector result intrinsics, use the generic demanded vector
    // support.
    if (auto *IIFVTy = dyn_cast<FixedVectorType>(II->getType())) {
      auto VWidth = IIFVTy->getNumElements();
      APInt UndefElts(VWidth, 0);
      APInt AllOnesEltMask(APInt::getAllOnes(VWidth));
      if (Value *V = SimplifyDemandedVectorElts(II, AllOnesEltMask, UndefElts)) {
        if (V != II)
          return replaceInstUsesWith(*II, V);
        return II;
      }
    }
  
    if (II->isCommutative()) {
      if (CallInst *NewCall = canonicalizeConstantArg0ToArg1(CI))
        return NewCall;
    }
  
    Intrinsic::ID IID = II->getIntrinsicID();
    switch (IID) {
    case Intrinsic::objectsize:
      if (Value *V = lowerObjectSizeCall(II, DL, &TLI, /*MustSucceed=*/false))
        return replaceInstUsesWith(CI, V);
      return nullptr;
    case Intrinsic::abs: {
      Value *IIOperand = II->getArgOperand(0);
      bool IntMinIsPoison = cast<Constant>(II->getArgOperand(1))->isOneValue();
  
      // abs(-x) -> abs(x)
      // TODO: Copy nsw if it was present on the neg?
      Value *X;
      if (match(IIOperand, m_Neg(m_Value(X))))
        return replaceOperand(*II, 0, X);
      if (match(IIOperand, m_Select(m_Value(), m_Value(X), m_Neg(m_Deferred(X)))))
        return replaceOperand(*II, 0, X);
      if (match(IIOperand, m_Select(m_Value(), m_Neg(m_Value(X)), m_Deferred(X))))
        return replaceOperand(*II, 0, X);
  
      if (Optional<bool> Sign = getKnownSign(IIOperand, II, DL, &AC, &DT)) {
        // abs(x) -> x if x >= 0
        if (!*Sign)
          return replaceInstUsesWith(*II, IIOperand);
  
        // abs(x) -> -x if x < 0
        if (IntMinIsPoison)
          return BinaryOperator::CreateNSWNeg(IIOperand);
        return BinaryOperator::CreateNeg(IIOperand);
      }
  
      // abs (sext X) --> zext (abs X*)
      // Clear the IsIntMin (nsw) bit on the abs to allow narrowing.
      if (match(IIOperand, m_OneUse(m_SExt(m_Value(X))))) {
        Value *NarrowAbs =
            Builder.CreateBinaryIntrinsic(Intrinsic::abs, X, Builder.getFalse());
        return CastInst::Create(Instruction::ZExt, NarrowAbs, II->getType());
      }
  
      // Match a complicated way to check if a number is odd/even:
      // abs (srem X, 2) --> and X, 1
      const APInt *C;
      if (match(IIOperand, m_SRem(m_Value(X), m_APInt(C))) && *C == 2)
        return BinaryOperator::CreateAnd(X, ConstantInt::get(II->getType(), 1));
  
      break;
    }
    case Intrinsic::umin: {
      Value *I0 = II->getArgOperand(0), *I1 = II->getArgOperand(1);
      // umin(x, 1) == zext(x != 0)
      if (match(I1, m_One())) {
        Value *Zero = Constant::getNullValue(I0->getType());
        Value *Cmp = Builder.CreateICmpNE(I0, Zero);
        return CastInst::Create(Instruction::ZExt, Cmp, II->getType());
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::umax: {
      Value *I0 = II->getArgOperand(0), *I1 = II->getArgOperand(1);
      Value *X, *Y;
      if (match(I0, m_ZExt(m_Value(X))) && match(I1, m_ZExt(m_Value(Y))) &&
          (I0->hasOneUse() || I1->hasOneUse()) && X->getType() == Y->getType()) {
        Value *NarrowMaxMin = Builder.CreateBinaryIntrinsic(IID, X, Y);
        return CastInst::Create(Instruction::ZExt, NarrowMaxMin, II->getType());
      }
      Constant *C;
      if (match(I0, m_ZExt(m_Value(X))) && match(I1, m_Constant(C)) &&
          I0->hasOneUse()) {
        Constant *NarrowC = ConstantExpr::getTrunc(C, X->getType());
        if (ConstantExpr::getZExt(NarrowC, II->getType()) == C) {
          Value *NarrowMaxMin = Builder.CreateBinaryIntrinsic(IID, X, NarrowC);
          return CastInst::Create(Instruction::ZExt, NarrowMaxMin, II->getType());
        }
      }
      // If both operands of unsigned min/max are sign-extended, it is still ok
      // to narrow the operation.
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::smax:
    case Intrinsic::smin: {
      Value *I0 = II->getArgOperand(0), *I1 = II->getArgOperand(1);
      Value *X, *Y;
      if (match(I0, m_SExt(m_Value(X))) && match(I1, m_SExt(m_Value(Y))) &&
          (I0->hasOneUse() || I1->hasOneUse()) && X->getType() == Y->getType()) {
        Value *NarrowMaxMin = Builder.CreateBinaryIntrinsic(IID, X, Y);
        return CastInst::Create(Instruction::SExt, NarrowMaxMin, II->getType());
      }
  
      Constant *C;
      if (match(I0, m_SExt(m_Value(X))) && match(I1, m_Constant(C)) &&
          I0->hasOneUse()) {
        Constant *NarrowC = ConstantExpr::getTrunc(C, X->getType());
        if (ConstantExpr::getSExt(NarrowC, II->getType()) == C) {
          Value *NarrowMaxMin = Builder.CreateBinaryIntrinsic(IID, X, NarrowC);
          return CastInst::Create(Instruction::SExt, NarrowMaxMin, II->getType());
        }
      }
  
      if (IID == Intrinsic::smax || IID == Intrinsic::smin) {
        // smax (neg nsw X), (neg nsw Y) --> neg nsw (smin X, Y)
        // smin (neg nsw X), (neg nsw Y) --> neg nsw (smax X, Y)
        // TODO: Canonicalize neg after min/max if I1 is constant.
        if (match(I0, m_NSWNeg(m_Value(X))) && match(I1, m_NSWNeg(m_Value(Y))) &&
            (I0->hasOneUse() || I1->hasOneUse())) {
          Intrinsic::ID InvID = getInverseMinMaxIntrinsic(IID);
          Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, X, Y);
          return BinaryOperator::CreateNSWNeg(InvMaxMin);
        }
      }
  
      // If we can eliminate ~A and Y is free to invert:
      // max ~A, Y --> ~(min A, ~Y)
      //
      // Examples:
      // max ~A, ~Y --> ~(min A, Y)
      // max ~A, C --> ~(min A, ~C)
      // max ~A, (max ~Y, ~Z) --> ~min( A, (min Y, Z))
      auto moveNotAfterMinMax = [&](Value *X, Value *Y) -> Instruction * {
        Value *A;
        if (match(X, m_OneUse(m_Not(m_Value(A)))) &&
            !isFreeToInvert(A, A->hasOneUse()) &&
            isFreeToInvert(Y, Y->hasOneUse())) {
          Value *NotY = Builder.CreateNot(Y);
          Intrinsic::ID InvID = getInverseMinMaxIntrinsic(IID);
          Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, A, NotY);
          return BinaryOperator::CreateNot(InvMaxMin);
        }
        return nullptr;
      };
  
      if (Instruction *I = moveNotAfterMinMax(I0, I1))
        return I;
      if (Instruction *I = moveNotAfterMinMax(I1, I0))
        return I;
  
      if (Instruction *I = moveAddAfterMinMax(II, Builder))
        return I;
  
      // smax(X, -X) --> abs(X)
      // smin(X, -X) --> -abs(X)
      // umax(X, -X) --> -abs(X)
      // umin(X, -X) --> abs(X)
      if (isKnownNegation(I0, I1)) {
        // We can choose either operand as the input to abs(), but if we can
        // eliminate the only use of a value, that's better for subsequent
        // transforms/analysis.
        if (I0->hasOneUse() && !I1->hasOneUse())
          std::swap(I0, I1);
  
        // This is some variant of abs(). See if we can propagate 'nsw' to the abs
        // operation and potentially its negation.
        bool IntMinIsPoison = isKnownNegation(I0, I1, /* NeedNSW */ true);
        Value *Abs = Builder.CreateBinaryIntrinsic(
            Intrinsic::abs, I0,
            ConstantInt::getBool(II->getContext(), IntMinIsPoison));
  
        // We don't have a "nabs" intrinsic, so negate if needed based on the
        // max/min operation.
        if (IID == Intrinsic::smin || IID == Intrinsic::umax)
          Abs = Builder.CreateNeg(Abs, "nabs", /* NUW */ false, IntMinIsPoison);
        return replaceInstUsesWith(CI, Abs);
      }
  
      if (Instruction *Sel = foldClampRangeOfTwo(II, Builder))
        return Sel;
  
      if (Instruction *SAdd = matchSAddSubSat(*II))
        return SAdd;
  
      if (match(I1, m_ImmConstant()))
        if (auto *Sel = dyn_cast<SelectInst>(I0))
          if (Instruction *R = FoldOpIntoSelect(*II, Sel))
            return R;
  
      if (Instruction *NewMinMax = reassociateMinMaxWithConstants(II))
        return NewMinMax;
  
      if (Instruction *NewMinMax = factorizeMinMaxTree(II))
         return NewMinMax;
  
      break;
    }
    case Intrinsic::bswap: {
      Value *IIOperand = II->getArgOperand(0);
      Value *X = nullptr;
  
      KnownBits Known = computeKnownBits(IIOperand, 0, II);
      uint64_t LZ = alignDown(Known.countMinLeadingZeros(), 8);
      uint64_t TZ = alignDown(Known.countMinTrailingZeros(), 8);
  
      // bswap(x) -> shift(x) if x has exactly one "active byte"
      if (Known.getBitWidth() - LZ - TZ == 8) {
        assert(LZ != TZ && "active byte cannot be in the middle");
        if (LZ > TZ)  // -> shl(x) if the "active byte" is in the low part of x
          return BinaryOperator::CreateNUWShl(
              IIOperand, ConstantInt::get(IIOperand->getType(), LZ - TZ));
        // -> lshr(x) if the "active byte" is in the high part of x
        return BinaryOperator::CreateExactLShr(
              IIOperand, ConstantInt::get(IIOperand->getType(), TZ - LZ));
      }
  
      // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
      if (match(IIOperand, m_Trunc(m_BSwap(m_Value(X))))) {
        unsigned C = X->getType()->getScalarSizeInBits() -
                     IIOperand->getType()->getScalarSizeInBits();
        Value *CV = ConstantInt::get(X->getType(), C);
        Value *V = Builder.CreateLShr(X, CV);
        return new TruncInst(V, IIOperand->getType());
      }
      break;
    }
    case Intrinsic::masked_load:
      if (Value *SimplifiedMaskedOp = simplifyMaskedLoad(*II))
        return replaceInstUsesWith(CI, SimplifiedMaskedOp);
      break;
    case Intrinsic::masked_store:
      return simplifyMaskedStore(*II);
    case Intrinsic::masked_gather:
      return simplifyMaskedGather(*II);
    case Intrinsic::masked_scatter:
      return simplifyMaskedScatter(*II);
    case Intrinsic::launder_invariant_group:
    case Intrinsic::strip_invariant_group:
      if (auto *SkippedBarrier = simplifyInvariantGroupIntrinsic(*II, *this))
        return replaceInstUsesWith(*II, SkippedBarrier);
      break;
    case Intrinsic::powi:
      if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
        // 0 and 1 are handled in instsimplify
        // powi(x, -1) -> 1/x
        if (Power->isMinusOne())
          return BinaryOperator::CreateFDivFMF(ConstantFP::get(CI.getType(), 1.0),
                                               II->getArgOperand(0), II);
        // powi(x, 2) -> x*x
        if (Power->equalsInt(2))
          return BinaryOperator::CreateFMulFMF(II->getArgOperand(0),
                                               II->getArgOperand(0), II);
  
        if (!Power->getValue()[0]) {
          Value *X;
          // If power is even:
          // powi(-x, p) -> powi(x, p)
          // powi(fabs(x), p) -> powi(x, p)
          // powi(copysign(x, y), p) -> powi(x, p)
          if (match(II->getArgOperand(0), m_FNeg(m_Value(X))) ||
              match(II->getArgOperand(0), m_FAbs(m_Value(X))) ||
              match(II->getArgOperand(0),
                    m_Intrinsic<Intrinsic::copysign>(m_Value(X), m_Value())))
            return replaceOperand(*II, 0, X);
        }
      }
      break;
  
    case Intrinsic::cttz:
    case Intrinsic::ctlz:
      if (auto *I = foldCttzCtlz(*II, *this))
        return I;
      break;
  
    case Intrinsic::ctpop:
      if (auto *I = foldCtpop(*II, *this))
        return I;
      break;
  
    case Intrinsic::fshl:
    case Intrinsic::fshr: {
      Value *Op0 = II->getArgOperand(0), *Op1 = II->getArgOperand(1);
      Type *Ty = II->getType();
      unsigned BitWidth = Ty->getScalarSizeInBits();
      Constant *ShAmtC;
      if (match(II->getArgOperand(2), m_ImmConstant(ShAmtC)) &&
          !ShAmtC->containsConstantExpression()) {
        // Canonicalize a shift amount constant operand to modulo the bit-width.
        Constant *WidthC = ConstantInt::get(Ty, BitWidth);
        Constant *ModuloC = ConstantExpr::getURem(ShAmtC, WidthC);
        if (ModuloC != ShAmtC)
          return replaceOperand(*II, 2, ModuloC);
  
        assert(ConstantExpr::getICmp(ICmpInst::ICMP_UGT, WidthC, ShAmtC) ==
                   ConstantInt::getTrue(CmpInst::makeCmpResultType(Ty)) &&
               "Shift amount expected to be modulo bitwidth");
  
        // Canonicalize funnel shift right by constant to funnel shift left. This
        // is not entirely arbitrary. For historical reasons, the backend may
        // recognize rotate left patterns but miss rotate right patterns.
        if (IID == Intrinsic::fshr) {
          // fshr X, Y, C --> fshl X, Y, (BitWidth - C)
          Constant *LeftShiftC = ConstantExpr::getSub(WidthC, ShAmtC);
          Module *Mod = II->getModule();
          Function *Fshl = Intrinsic::getDeclaration(Mod, Intrinsic::fshl, Ty);
          return CallInst::Create(Fshl, { Op0, Op1, LeftShiftC });
        }
        assert(IID == Intrinsic::fshl &&
               "All funnel shifts by simple constants should go left");
  
        // fshl(X, 0, C) --> shl X, C
        // fshl(X, undef, C) --> shl X, C
        if (match(Op1, m_ZeroInt()) || match(Op1, m_Undef()))
          return BinaryOperator::CreateShl(Op0, ShAmtC);
  
        // fshl(0, X, C) --> lshr X, (BW-C)
        // fshl(undef, X, C) --> lshr X, (BW-C)
        if (match(Op0, m_ZeroInt()) || match(Op0, m_Undef()))
          return BinaryOperator::CreateLShr(Op1,
                                            ConstantExpr::getSub(WidthC, ShAmtC));
  
        // fshl i16 X, X, 8 --> bswap i16 X (reduce to more-specific form)
        if (Op0 == Op1 && BitWidth == 16 && match(ShAmtC, m_SpecificInt(8))) {
          Module *Mod = II->getModule();
          Function *Bswap = Intrinsic::getDeclaration(Mod, Intrinsic::bswap, Ty);
          return CallInst::Create(Bswap, { Op0 });
        }
      }
  
      // Left or right might be masked.
      if (SimplifyDemandedInstructionBits(*II))
        return &CI;
  
      // The shift amount (operand 2) of a funnel shift is modulo the bitwidth,
      // so only the low bits of the shift amount are demanded if the bitwidth is
      // a power-of-2.
      if (!isPowerOf2_32(BitWidth))
        break;
      APInt Op2Demanded = APInt::getLowBitsSet(BitWidth, Log2_32_Ceil(BitWidth));
      KnownBits Op2Known(BitWidth);
      if (SimplifyDemandedBits(II, 2, Op2Demanded, Op2Known))
        return &CI;
      break;
    }
    case Intrinsic::uadd_with_overflow:
    case Intrinsic::sadd_with_overflow: {
      if (Instruction *I = foldIntrinsicWithOverflowCommon(II))
        return I;
  
      // Given 2 constant operands whose sum does not overflow:
      // uaddo (X +nuw C0), C1 -> uaddo X, C0 + C1
      // saddo (X +nsw C0), C1 -> saddo X, C0 + C1
      Value *X;
      const APInt *C0, *C1;
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
      bool IsSigned = IID == Intrinsic::sadd_with_overflow;
      bool HasNWAdd = IsSigned ? match(Arg0, m_NSWAdd(m_Value(X), m_APInt(C0)))
                               : match(Arg0, m_NUWAdd(m_Value(X), m_APInt(C0)));
      if (HasNWAdd && match(Arg1, m_APInt(C1))) {
        bool Overflow;
        APInt NewC =
            IsSigned ? C1->sadd_ov(*C0, Overflow) : C1->uadd_ov(*C0, Overflow);
        if (!Overflow)
          return replaceInstUsesWith(
              *II, Builder.CreateBinaryIntrinsic(
                       IID, X, ConstantInt::get(Arg1->getType(), NewC)));
      }
      break;
    }
  
    case Intrinsic::umul_with_overflow:
    case Intrinsic::smul_with_overflow:
    case Intrinsic::usub_with_overflow:
      if (Instruction *I = foldIntrinsicWithOverflowCommon(II))
        return I;
      break;
  
    case Intrinsic::ssub_with_overflow: {
      if (Instruction *I = foldIntrinsicWithOverflowCommon(II))
        return I;
  
      Constant *C;
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
      // Given a constant C that is not the minimum signed value
      // for an integer of a given bit width:
      //
      // ssubo X, C -> saddo X, -C
      if (match(Arg1, m_Constant(C)) && C->isNotMinSignedValue()) {
        Value *NegVal = ConstantExpr::getNeg(C);
        // Build a saddo call that is equivalent to the discovered
        // ssubo call.
        return replaceInstUsesWith(
            *II, Builder.CreateBinaryIntrinsic(Intrinsic::sadd_with_overflow,
                                               Arg0, NegVal));
      }
  
      break;
    }
  
    case Intrinsic::uadd_sat:
    case Intrinsic::sadd_sat:
    case Intrinsic::usub_sat:
    case Intrinsic::ssub_sat: {
      SaturatingInst *SI = cast<SaturatingInst>(II);
      Type *Ty = SI->getType();
      Value *Arg0 = SI->getLHS();
      Value *Arg1 = SI->getRHS();
  
      // Make use of known overflow information.
      OverflowResult OR = computeOverflow(SI->getBinaryOp(), SI->isSigned(),
                                          Arg0, Arg1, SI);
      switch (OR) {
        case OverflowResult::MayOverflow:
          break;
        case OverflowResult::NeverOverflows:
          if (SI->isSigned())
            return BinaryOperator::CreateNSW(SI->getBinaryOp(), Arg0, Arg1);
          else
            return BinaryOperator::CreateNUW(SI->getBinaryOp(), Arg0, Arg1);
        case OverflowResult::AlwaysOverflowsLow: {
          unsigned BitWidth = Ty->getScalarSizeInBits();
          APInt Min = APSInt::getMinValue(BitWidth, !SI->isSigned());
          return replaceInstUsesWith(*SI, ConstantInt::get(Ty, Min));
        }
        case OverflowResult::AlwaysOverflowsHigh: {
          unsigned BitWidth = Ty->getScalarSizeInBits();
          APInt Max = APSInt::getMaxValue(BitWidth, !SI->isSigned());
          return replaceInstUsesWith(*SI, ConstantInt::get(Ty, Max));
        }
      }
  
      // ssub.sat(X, C) -> sadd.sat(X, -C) if C != MIN
      Constant *C;
      if (IID == Intrinsic::ssub_sat && match(Arg1, m_Constant(C)) &&
          C->isNotMinSignedValue()) {
        Value *NegVal = ConstantExpr::getNeg(C);
        return replaceInstUsesWith(
            *II, Builder.CreateBinaryIntrinsic(
                Intrinsic::sadd_sat, Arg0, NegVal));
      }
  
      // sat(sat(X + Val2) + Val) -> sat(X + (Val+Val2))
      // sat(sat(X - Val2) - Val) -> sat(X - (Val+Val2))
      // if Val and Val2 have the same sign
      if (auto *Other = dyn_cast<IntrinsicInst>(Arg0)) {
        Value *X;
        const APInt *Val, *Val2;
        APInt NewVal;
        bool IsUnsigned =
            IID == Intrinsic::uadd_sat || IID == Intrinsic::usub_sat;
        if (Other->getIntrinsicID() == IID &&
            match(Arg1, m_APInt(Val)) &&
            match(Other->getArgOperand(0), m_Value(X)) &&
            match(Other->getArgOperand(1), m_APInt(Val2))) {
          if (IsUnsigned)
            NewVal = Val->uadd_sat(*Val2);
          else if (Val->isNonNegative() == Val2->isNonNegative()) {
            bool Overflow;
            NewVal = Val->sadd_ov(*Val2, Overflow);
            if (Overflow) {
              // Both adds together may add more than SignedMaxValue
              // without saturating the final result.
              break;
            }
          } else {
            // Cannot fold saturated addition with different signs.
            break;
          }
  
          return replaceInstUsesWith(
              *II, Builder.CreateBinaryIntrinsic(
                       IID, X, ConstantInt::get(II->getType(), NewVal)));
        }
      }
      break;
    }
  
    case Intrinsic::minnum:
    case Intrinsic::maxnum:
    case Intrinsic::minimum:
    case Intrinsic::maximum: {
      Value *Arg0 = II->getArgOperand(0);
      Value *Arg1 = II->getArgOperand(1);
      Value *X, *Y;
      if (match(Arg0, m_FNeg(m_Value(X))) && match(Arg1, m_FNeg(m_Value(Y))) &&
          (Arg0->hasOneUse() || Arg1->hasOneUse())) {
        // If both operands are negated, invert the call and negate the result:
        // min(-X, -Y) --> -(max(X, Y))
        // max(-X, -Y) --> -(min(X, Y))
        Intrinsic::ID NewIID;
        switch (IID) {
        case Intrinsic::maxnum:
          NewIID = Intrinsic::minnum;
          break;
        case Intrinsic::minnum:
          NewIID = Intrinsic::maxnum;
          break;
        case Intrinsic::maximum:
          NewIID = Intrinsic::minimum;
          break;
        case Intrinsic::minimum:
          NewIID = Intrinsic::maximum;
          break;
        default:
          llvm_unreachable("unexpected intrinsic ID");
        }
        Value *NewCall = Builder.CreateBinaryIntrinsic(NewIID, X, Y, II);
        Instruction *FNeg = UnaryOperator::CreateFNeg(NewCall);
        FNeg->copyIRFlags(II);
        return FNeg;
      }
  
      // m(m(X, C2), C1) -> m(X, C)
      const APFloat *C1, *C2;
      if (auto *M = dyn_cast<IntrinsicInst>(Arg0)) {
        if (M->getIntrinsicID() == IID && match(Arg1, m_APFloat(C1)) &&
            ((match(M->getArgOperand(0), m_Value(X)) &&
              match(M->getArgOperand(1), m_APFloat(C2))) ||
             (match(M->getArgOperand(1), m_Value(X)) &&
              match(M->getArgOperand(0), m_APFloat(C2))))) {
          APFloat Res(0.0);
          switch (IID) {
          case Intrinsic::maxnum:
            Res = maxnum(*C1, *C2);
            break;
          case Intrinsic::minnum:
            Res = minnum(*C1, *C2);
            break;
          case Intrinsic::maximum:
            Res = maximum(*C1, *C2);
            break;
          case Intrinsic::minimum:
            Res = minimum(*C1, *C2);
            break;
          default:
            llvm_unreachable("unexpected intrinsic ID");
          }
          Instruction *NewCall = Builder.CreateBinaryIntrinsic(
              IID, X, ConstantFP::get(Arg0->getType(), Res), II);
          // TODO: Conservatively intersecting FMF. If Res == C2, the transform
          //       was a simplification (so Arg0 and its original flags could
          //       propagate?)
          NewCall->andIRFlags(M);
          return replaceInstUsesWith(*II, NewCall);
        }
      }
  
      // m((fpext X), (fpext Y)) -> fpext (m(X, Y))
      if (match(Arg0, m_OneUse(m_FPExt(m_Value(X)))) &&
          match(Arg1, m_OneUse(m_FPExt(m_Value(Y)))) &&
          X->getType() == Y->getType()) {
        Value *NewCall =
            Builder.CreateBinaryIntrinsic(IID, X, Y, II, II->getName());
        return new FPExtInst(NewCall, II->getType());
      }
  
      // max X, -X --> fabs X
      // min X, -X --> -(fabs X)
      // TODO: Remove one-use limitation? That is obviously better for max.
      //       It would be an extra instruction for min (fnabs), but that is
      //       still likely better for analysis and codegen.
      if ((match(Arg0, m_OneUse(m_FNeg(m_Value(X)))) && Arg1 == X) ||
          (match(Arg1, m_OneUse(m_FNeg(m_Value(X)))) && Arg0 == X)) {
        Value *R = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, X, II);
        if (IID == Intrinsic::minimum || IID == Intrinsic::minnum)
          R = Builder.CreateFNegFMF(R, II);
        return replaceInstUsesWith(*II, R);
      }
  
      break;
    }
    case Intrinsic::fmuladd: {
      // Canonicalize fast fmuladd to the separate fmul + fadd.
      if (II->isFast()) {
        BuilderTy::FastMathFlagGuard Guard(Builder);
        Builder.setFastMathFlags(II->getFastMathFlags());
        Value *Mul = Builder.CreateFMul(II->getArgOperand(0),
                                        II->getArgOperand(1));
        Value *Add = Builder.CreateFAdd(Mul, II->getArgOperand(2));
        Add->takeName(II);
        return replaceInstUsesWith(*II, Add);
      }
  
      // Try to simplify the underlying FMul.
      if (Value *V = SimplifyFMulInst(II->getArgOperand(0), II->getArgOperand(1),
                                      II->getFastMathFlags(),
                                      SQ.getWithInstruction(II))) {
        auto *FAdd = BinaryOperator::CreateFAdd(V, II->getArgOperand(2));
        FAdd->copyFastMathFlags(II);
        return FAdd;
      }
  
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::fma: {
      // fma fneg(x), fneg(y), z -> fma x, y, z
      Value *Src0 = II->getArgOperand(0);
      Value *Src1 = II->getArgOperand(1);
      Value *X, *Y;
      if (match(Src0, m_FNeg(m_Value(X))) && match(Src1, m_FNeg(m_Value(Y)))) {
        replaceOperand(*II, 0, X);
        replaceOperand(*II, 1, Y);
        return II;
      }
  
      // fma fabs(x), fabs(x), z -> fma x, x, z
      if (match(Src0, m_FAbs(m_Value(X))) &&
          match(Src1, m_FAbs(m_Specific(X)))) {
        replaceOperand(*II, 0, X);
        replaceOperand(*II, 1, X);
        return II;
      }
  
      // Try to simplify the underlying FMul. We can only apply simplifications
      // that do not require rounding.
      if (Value *V = SimplifyFMAFMul(II->getArgOperand(0), II->getArgOperand(1),
                                     II->getFastMathFlags(),
                                     SQ.getWithInstruction(II))) {
        auto *FAdd = BinaryOperator::CreateFAdd(V, II->getArgOperand(2));
        FAdd->copyFastMathFlags(II);
        return FAdd;
      }
  
      // fma x, y, 0 -> fmul x, y
      // This is always valid for -0.0, but requires nsz for +0.0 as
      // -0.0 + 0.0 = 0.0, which would not be the same as the fmul on its own.
      if (match(II->getArgOperand(2), m_NegZeroFP()) ||
          (match(II->getArgOperand(2), m_PosZeroFP()) &&
           II->getFastMathFlags().noSignedZeros()))
        return BinaryOperator::CreateFMulFMF(Src0, Src1, II);
  
      break;
    }
    case Intrinsic::copysign: {
      Value *Mag = II->getArgOperand(0), *Sign = II->getArgOperand(1);
      if (SignBitMustBeZero(Sign, &TLI)) {
        // If we know that the sign argument is positive, reduce to FABS:
        // copysign Mag, +Sign --> fabs Mag
        Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, Mag, II);
        return replaceInstUsesWith(*II, Fabs);
      }
      // TODO: There should be a ValueTracking sibling like SignBitMustBeOne.
      const APFloat *C;
      if (match(Sign, m_APFloat(C)) && C->isNegative()) {
        // If we know that the sign argument is negative, reduce to FNABS:
        // copysign Mag, -Sign --> fneg (fabs Mag)
        Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, Mag, II);
        return replaceInstUsesWith(*II, Builder.CreateFNegFMF(Fabs, II));
      }
  
      // Propagate sign argument through nested calls:
      // copysign Mag, (copysign ?, X) --> copysign Mag, X
      Value *X;
      if (match(Sign, m_Intrinsic<Intrinsic::copysign>(m_Value(), m_Value(X))))
        return replaceOperand(*II, 1, X);
  
      // Peek through changes of magnitude's sign-bit. This call rewrites those:
      // copysign (fabs X), Sign --> copysign X, Sign
      // copysign (fneg X), Sign --> copysign X, Sign
      if (match(Mag, m_FAbs(m_Value(X))) || match(Mag, m_FNeg(m_Value(X))))
        return replaceOperand(*II, 0, X);
  
      break;
    }
    case Intrinsic::fabs: {
      Value *Cond, *TVal, *FVal;
      if (match(II->getArgOperand(0),
                m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))) {
        // fabs (select Cond, TrueC, FalseC) --> select Cond, AbsT, AbsF
        if (isa<Constant>(TVal) && isa<Constant>(FVal)) {
          CallInst *AbsT = Builder.CreateCall(II->getCalledFunction(), {TVal});
          CallInst *AbsF = Builder.CreateCall(II->getCalledFunction(), {FVal});
          return SelectInst::Create(Cond, AbsT, AbsF);
        }
        // fabs (select Cond, -FVal, FVal) --> fabs FVal
        if (match(TVal, m_FNeg(m_Specific(FVal))))
          return replaceOperand(*II, 0, FVal);
        // fabs (select Cond, TVal, -TVal) --> fabs TVal
        if (match(FVal, m_FNeg(m_Specific(TVal))))
          return replaceOperand(*II, 0, TVal);
      }
  
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::ceil:
    case Intrinsic::floor:
    case Intrinsic::round:
    case Intrinsic::roundeven:
    case Intrinsic::nearbyint:
    case Intrinsic::rint:
    case Intrinsic::trunc: {
      Value *ExtSrc;
      if (match(II->getArgOperand(0), m_OneUse(m_FPExt(m_Value(ExtSrc))))) {
        // Narrow the call: intrinsic (fpext x) -> fpext (intrinsic x)
        Value *NarrowII = Builder.CreateUnaryIntrinsic(IID, ExtSrc, II);
        return new FPExtInst(NarrowII, II->getType());
      }
      break;
    }
    case Intrinsic::cos:
    case Intrinsic::amdgcn_cos: {
      Value *X;
      Value *Src = II->getArgOperand(0);
      if (match(Src, m_FNeg(m_Value(X))) || match(Src, m_FAbs(m_Value(X)))) {
        // cos(-x) -> cos(x)
        // cos(fabs(x)) -> cos(x)
        return replaceOperand(*II, 0, X);
      }
      break;
    }
    case Intrinsic::sin: {
      Value *X;
      if (match(II->getArgOperand(0), m_OneUse(m_FNeg(m_Value(X))))) {
        // sin(-x) --> -sin(x)
        Value *NewSin = Builder.CreateUnaryIntrinsic(Intrinsic::sin, X, II);
        Instruction *FNeg = UnaryOperator::CreateFNeg(NewSin);
        FNeg->copyFastMathFlags(II);
        return FNeg;
      }
      break;
    }
  
    case Intrinsic::arm_neon_vtbl1:
    case Intrinsic::aarch64_neon_tbl1:
      if (Value *V = simplifyNeonTbl1(*II, Builder))
        return replaceInstUsesWith(*II, V);
      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 = (IID == Intrinsic::arm_neon_vmullu ||
                   IID == 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::arm_neon_aesd:
    case Intrinsic::arm_neon_aese:
    case Intrinsic::aarch64_crypto_aesd:
    case Intrinsic::aarch64_crypto_aese: {
      Value *DataArg = II->getArgOperand(0);
      Value *KeyArg  = II->getArgOperand(1);
  
      // Try to use the builtin XOR in AESE and AESD to eliminate a prior XOR
      Value *Data, *Key;
      if (match(KeyArg, m_ZeroInt()) &&
          match(DataArg, m_Xor(m_Value(Data), m_Value(Key)))) {
        replaceOperand(*II, 0, Data);
        replaceOperand(*II, 1, Key);
        return II;
      }
      break;
    }
    case Intrinsic::hexagon_V6_vandvrt:
    case Intrinsic::hexagon_V6_vandvrt_128B: {
      // Simplify Q -> V -> Q conversion.
      if (auto Op0 = dyn_cast<IntrinsicInst>(II->getArgOperand(0))) {
        Intrinsic::ID ID0 = Op0->getIntrinsicID();
        if (ID0 != Intrinsic::hexagon_V6_vandqrt &&
            ID0 != Intrinsic::hexagon_V6_vandqrt_128B)
          break;
        Value *Bytes = Op0->getArgOperand(1), *Mask = II->getArgOperand(1);
        uint64_t Bytes1 = computeKnownBits(Bytes, 0, Op0).One.getZExtValue();
        uint64_t Mask1 = computeKnownBits(Mask, 0, II).One.getZExtValue();
        // Check if every byte has common bits in Bytes and Mask.
        uint64_t C = Bytes1 & Mask1;
        if ((C & 0xFF) && (C & 0xFF00) && (C & 0xFF0000) && (C & 0xFF000000))
          return replaceInstUsesWith(*II, Op0->getArgOperand(0));
      }
      break;
    }
    case Intrinsic::stackrestore: {
      enum class ClassifyResult {
        None,
        Alloca,
        StackRestore,
        CallWithSideEffects,
      };
      auto Classify = [](const Instruction *I) {
        if (isa<AllocaInst>(I))
          return ClassifyResult::Alloca;
  
        if (auto *CI = dyn_cast<CallInst>(I)) {
          if (auto *II = dyn_cast<IntrinsicInst>(CI)) {
            if (II->getIntrinsicID() == Intrinsic::stackrestore)
              return ClassifyResult::StackRestore;
  
            if (II->mayHaveSideEffects())
              return ClassifyResult::CallWithSideEffects;
          } else {
            // Consider all non-intrinsic calls to be side effects
            return ClassifyResult::CallWithSideEffects;
          }
        }
  
        return ClassifyResult::None;
      };
  
      // If the stacksave and the stackrestore are in the same BB, and there is
      // no intervening call, alloca, or stackrestore of a different stacksave,
      // 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 &&
            SS->getParent() == II->getParent()) {
          BasicBlock::iterator BI(SS);
          bool CannotRemove = false;
          for (++BI; &*BI != II; ++BI) {
            switch (Classify(&*BI)) {
            case ClassifyResult::None:
              // So far so good, look at next instructions.
              break;
  
            case ClassifyResult::StackRestore:
              // If we found an intervening stackrestore for a different
              // stacksave, we can't remove the stackrestore. Otherwise, continue.
              if (cast<IntrinsicInst>(*BI).getArgOperand(0) != SS)
                CannotRemove = true;
              break;
  
            case ClassifyResult::Alloca:
            case ClassifyResult::CallWithSideEffects:
              // If we found an alloca, a non-intrinsic call, or an intrinsic
              // call with side effects, we can't remove the stackrestore.
              CannotRemove = true;
              break;
            }
            if (CannotRemove)
              break;
          }
  
          if (!CannotRemove)
            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);
      Instruction *TI = II->getParent()->getTerminator();
      bool CannotRemove = false;
      for (++BI; &*BI != TI; ++BI) {
        switch (Classify(&*BI)) {
        case ClassifyResult::None:
          // So far so good, look at next instructions.
          break;
  
        case ClassifyResult::StackRestore:
          // If there is a stackrestore below this one, remove this one.
          return eraseInstFromFunction(CI);
  
        case ClassifyResult::Alloca:
        case ClassifyResult::CallWithSideEffects:
          // If we found an alloca, a non-intrinsic call, or an intrinsic call
          // with side effects (such as llvm.stacksave and llvm.read_register),
          // we can't remove the stack restore.
          CannotRemove = true;
          break;
        }
        if (CannotRemove)
          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_end:
      // Asan needs to poison memory to detect invalid access which is possible
      // even for empty lifetime range.
      if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress) ||
          II->getFunction()->hasFnAttribute(Attribute::SanitizeMemory) ||
          II->getFunction()->hasFnAttribute(Attribute::SanitizeHWAddress))
        break;
  
      if (removeTriviallyEmptyRange(*II, *this, [](const IntrinsicInst &I) {
            return I.getIntrinsicID() == Intrinsic::lifetime_start;
          }))
        return nullptr;
      break;
    case Intrinsic::assume: {
      Value *IIOperand = II->getArgOperand(0);
      SmallVector<OperandBundleDef, 4> OpBundles;
      II->getOperandBundlesAsDefs(OpBundles);
  
      /// This will remove the boolean Condition from the assume given as
      /// argument and remove the assume if it becomes useless.
      /// always returns nullptr for use as a return values.
      auto RemoveConditionFromAssume = [&](Instruction *Assume) -> Instruction * {
        assert(isa<AssumeInst>(Assume));
        if (isAssumeWithEmptyBundle(*cast<AssumeInst>(II)))
          return eraseInstFromFunction(CI);
        replaceUse(II->getOperandUse(0), ConstantInt::getTrue(II->getContext()));
        return nullptr;
      };
      // Remove an assume if it is followed by an identical assume.
      // TODO: Do we need this? Unless there are conflicting assumptions, the
      // computeKnownBits(IIOperand) below here eliminates redundant assumes.
      Instruction *Next = II->getNextNonDebugInstruction();
      if (match(Next, m_Intrinsic<Intrinsic::assume>(m_Specific(IIOperand))))
        return RemoveConditionFromAssume(Next);
  
      // Canonicalize assume(a && b) -> assume(a); assume(b);
      // Note: New assumption intrinsics created here are registered by
      // the InstCombineIRInserter object.
      FunctionType *AssumeIntrinsicTy = II->getFunctionType();
      Value *AssumeIntrinsic = II->getCalledOperand();
      Value *A, *B;
      if (match(IIOperand, m_LogicalAnd(m_Value(A), m_Value(B)))) {
        Builder.CreateCall(AssumeIntrinsicTy, AssumeIntrinsic, A, OpBundles,
                           II->getName());
        Builder.CreateCall(AssumeIntrinsicTy, AssumeIntrinsic, B, II->getName());
        return eraseInstFromFunction(*II);
      }
      // assume(!(a || b)) -> assume(!a); assume(!b);
      if (match(IIOperand, m_Not(m_LogicalOr(m_Value(A), m_Value(B))))) {
        Builder.CreateCall(AssumeIntrinsicTy, AssumeIntrinsic,
                           Builder.CreateNot(A), OpBundles, II->getName());
        Builder.CreateCall(AssumeIntrinsicTy, 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)
      CmpInst::Predicate Pred;
      Instruction *LHS;
      if (match(IIOperand, m_ICmp(Pred, m_Instruction(LHS), m_Zero())) &&
          Pred == ICmpInst::ICMP_NE && LHS->getOpcode() == Instruction::Load &&
          LHS->getType()->isPointerTy() &&
          isValidAssumeForContext(II, LHS, &DT)) {
        MDNode *MD = MDNode::get(II->getContext(), None);
        LHS->setMetadata(LLVMContext::MD_nonnull, MD);
        return RemoveConditionFromAssume(II);
  
        // TODO: apply nonnull return attributes to calls and invokes
        // TODO: apply range metadata for range check patterns?
      }
  
      // Convert nonnull assume like:
      // %A = icmp ne i32* %PTR, null
      // call void @llvm.assume(i1 %A)
      // into
      // call void @llvm.assume(i1 true) [ "nonnull"(i32* %PTR) ]
      if (EnableKnowledgeRetention &&
          match(IIOperand, m_Cmp(Pred, m_Value(A), m_Zero())) &&
          Pred == CmpInst::ICMP_NE && A->getType()->isPointerTy()) {
        if (auto *Replacement = buildAssumeFromKnowledge(
                {RetainedKnowledge{Attribute::NonNull, 0, A}}, Next, &AC, &DT)) {
  
          Replacement->insertBefore(Next);
          AC.registerAssumption(Replacement);
          return RemoveConditionFromAssume(II);
        }
      }
  
      // Convert alignment assume like:
      // %B = ptrtoint i32* %A to i64
      // %C = and i64 %B, Constant
      // %D = icmp eq i64 %C, 0
      // call void @llvm.assume(i1 %D)
      // into
      // call void @llvm.assume(i1 true) [ "align"(i32* [[A]], i64  Constant + 1)]
      uint64_t AlignMask;
      if (EnableKnowledgeRetention &&
          match(IIOperand,
                m_Cmp(Pred, m_And(m_Value(A), m_ConstantInt(AlignMask)),
                      m_Zero())) &&
          Pred == CmpInst::ICMP_EQ) {
        if (isPowerOf2_64(AlignMask + 1)) {
          uint64_t Offset = 0;
          match(A, m_Add(m_Value(A), m_ConstantInt(Offset)));
          if (match(A, m_PtrToInt(m_Value(A)))) {
            /// Note: this doesn't preserve the offset information but merges
            /// offset and alignment.
            /// TODO: we can generate a GEP instead of merging the alignment with
            /// the offset.
            RetainedKnowledge RK{Attribute::Alignment,
                                 (unsigned)MinAlign(Offset, AlignMask + 1), A};
            if (auto *Replacement =
                    buildAssumeFromKnowledge(RK, Next, &AC, &DT)) {
  
              Replacement->insertAfter(II);
              AC.registerAssumption(Replacement);
            }
            return RemoveConditionFromAssume(II);
          }
        }
      }
  
      /// Canonicalize Knowledge in operand bundles.
      if (EnableKnowledgeRetention && II->hasOperandBundles()) {
        for (unsigned Idx = 0; Idx < II->getNumOperandBundles(); Idx++) {
          auto &BOI = II->bundle_op_info_begin()[Idx];
          RetainedKnowledge RK =
            llvm::getKnowledgeFromBundle(cast<AssumeInst>(*II), BOI);
          if (BOI.End - BOI.Begin > 2)
            continue; // Prevent reducing knowledge in an align with offset since
                      // extracting a RetainedKnowledge form them looses offset
                      // information
          RetainedKnowledge CanonRK =
            llvm::simplifyRetainedKnowledge(cast<AssumeInst>(II), RK,
                                            &getAssumptionCache(),
                                            &getDominatorTree());
          if (CanonRK == RK)
            continue;
          if (!CanonRK) {
            if (BOI.End - BOI.Begin > 0) {
              Worklist.pushValue(II->op_begin()[BOI.Begin]);
              Value::dropDroppableUse(II->op_begin()[BOI.Begin]);
            }
            continue;
          }
          assert(RK.AttrKind == CanonRK.AttrKind);
          if (BOI.End - BOI.Begin > 0)
            II->op_begin()[BOI.Begin].set(CanonRK.WasOn);
          if (BOI.End - BOI.Begin > 1)
            II->op_begin()[BOI.Begin + 1].set(ConstantInt::get(
                Type::getInt64Ty(II->getContext()), CanonRK.ArgValue));
          if (RK.WasOn)
            Worklist.pushValue(RK.WasOn);
          return II;
        }
      }
  
      // If there is a dominating assume with the same condition as this one,
      // then this one is redundant, and should be removed.
      KnownBits Known(1);
      computeKnownBits(IIOperand, Known, 0, II);
      if (Known.isAllOnes() && isAssumeWithEmptyBundle(cast<AssumeInst>(*II)))
        return eraseInstFromFunction(*II);
  
      // Update the cache of affected values for this assumption (we might be
      // here because we just simplified the condition).
      AC.updateAffectedValues(cast<AssumeInst>(II));
      break;
    }
    case Intrinsic::experimental_guard: {
      // Is this guard followed by another guard?  We scan forward over a small
      // fixed window of instructions to handle common cases with conditions
      // computed between guards.
      Instruction *NextInst = II->getNextNonDebugInstruction();
      for (unsigned i = 0; i < GuardWideningWindow; i++) {
        // Note: Using context-free form to avoid compile time blow up
        if (!isSafeToSpeculativelyExecute(NextInst))
          break;
        NextInst = NextInst->getNextNonDebugInstruction();
      }
      Value *NextCond = nullptr;
      if (match(NextInst,
                m_Intrinsic<Intrinsic::experimental_guard>(m_Value(NextCond)))) {
        Value *CurrCond = II->getArgOperand(0);
  
        // Remove a guard that it is immediately preceded by an identical guard.
        // Otherwise canonicalize guard(a); guard(b) -> guard(a & b).
        if (CurrCond != NextCond) {
          Instruction *MoveI = II->getNextNonDebugInstruction();
          while (MoveI != NextInst) {
            auto *Temp = MoveI;
            MoveI = MoveI->getNextNonDebugInstruction();
            Temp->moveBefore(II);
          }
          replaceOperand(*II, 0, Builder.CreateAnd(CurrCond, NextCond));
        }
        eraseInstFromFunction(*NextInst);
        return II;
      }
      break;
    }
    case Intrinsic::experimental_vector_insert: {
      Value *Vec = II->getArgOperand(0);
      Value *SubVec = II->getArgOperand(1);
      Value *Idx = II->getArgOperand(2);
      auto *DstTy = dyn_cast<FixedVectorType>(II->getType());
      auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType());
      auto *SubVecTy = dyn_cast<FixedVectorType>(SubVec->getType());
  
      // Only canonicalize if the destination vector, Vec, and SubVec are all
      // fixed vectors.
      if (DstTy && VecTy && SubVecTy) {
        unsigned DstNumElts = DstTy->getNumElements();
        unsigned VecNumElts = VecTy->getNumElements();
        unsigned SubVecNumElts = SubVecTy->getNumElements();
        unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue();
  
        // An insert that entirely overwrites Vec with SubVec is a nop.
        if (VecNumElts == SubVecNumElts)
          return replaceInstUsesWith(CI, SubVec);
  
        // Widen SubVec into a vector of the same width as Vec, since
        // shufflevector requires the two input vectors to be the same width.
        // Elements beyond the bounds of SubVec within the widened vector are
        // undefined.
        SmallVector<int, 8> WidenMask;
        unsigned i;
        for (i = 0; i != SubVecNumElts; ++i)
          WidenMask.push_back(i);
        for (; i != VecNumElts; ++i)
          WidenMask.push_back(UndefMaskElem);
  
        Value *WidenShuffle = Builder.CreateShuffleVector(SubVec, WidenMask);
  
        SmallVector<int, 8> Mask;
        for (unsigned i = 0; i != IdxN; ++i)
          Mask.push_back(i);
        for (unsigned i = DstNumElts; i != DstNumElts + SubVecNumElts; ++i)
          Mask.push_back(i);
        for (unsigned i = IdxN + SubVecNumElts; i != DstNumElts; ++i)
          Mask.push_back(i);
  
        Value *Shuffle = Builder.CreateShuffleVector(Vec, WidenShuffle, Mask);
        return replaceInstUsesWith(CI, Shuffle);
      }
      break;
    }
    case Intrinsic::experimental_vector_extract: {
      Value *Vec = II->getArgOperand(0);
      Value *Idx = II->getArgOperand(1);
  
      auto *DstTy = dyn_cast<FixedVectorType>(II->getType());
      auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType());
  
      // Only canonicalize if the the destination vector and Vec are fixed
      // vectors.
      if (DstTy && VecTy) {
        unsigned DstNumElts = DstTy->getNumElements();
        unsigned VecNumElts = VecTy->getNumElements();
        unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue();
  
        // Extracting the entirety of Vec is a nop.
        if (VecNumElts == DstNumElts) {
          replaceInstUsesWith(CI, Vec);
          return eraseInstFromFunction(CI);
        }
  
        SmallVector<int, 8> Mask;
        for (unsigned i = 0; i != DstNumElts; ++i)
          Mask.push_back(IdxN + i);
  
        Value *Shuffle = Builder.CreateShuffleVector(Vec, Mask);
        return replaceInstUsesWith(CI, Shuffle);
      }
      break;
    }
    case Intrinsic::experimental_vector_reverse: {
      Value *BO0, *BO1, *X, *Y;
      Value *Vec = II->getArgOperand(0);
      if (match(Vec, m_OneUse(m_BinOp(m_Value(BO0), m_Value(BO1))))) {
        auto *OldBinOp = cast<BinaryOperator>(Vec);
        if (match(BO0, m_Intrinsic<Intrinsic::experimental_vector_reverse>(
                           m_Value(X)))) {
          // rev(binop rev(X), rev(Y)) --> binop X, Y
          if (match(BO1, m_Intrinsic<Intrinsic::experimental_vector_reverse>(
                             m_Value(Y))))
            return replaceInstUsesWith(CI,
                                       BinaryOperator::CreateWithCopiedFlags(
                                           OldBinOp->getOpcode(), X, Y, OldBinOp,
                                           OldBinOp->getName(), II));
          // rev(binop rev(X), BO1Splat) --> binop X, BO1Splat
          if (isSplatValue(BO1))
            return replaceInstUsesWith(CI,
                                       BinaryOperator::CreateWithCopiedFlags(
                                           OldBinOp->getOpcode(), X, BO1,
                                           OldBinOp, OldBinOp->getName(), II));
        }
        // rev(binop BO0Splat, rev(Y)) --> binop BO0Splat, Y
        if (match(BO1, m_Intrinsic<Intrinsic::experimental_vector_reverse>(
                           m_Value(Y))) &&
            isSplatValue(BO0))
          return replaceInstUsesWith(CI, BinaryOperator::CreateWithCopiedFlags(
                                             OldBinOp->getOpcode(), BO0, Y,
                                             OldBinOp, OldBinOp->getName(), II));
      }
      // rev(unop rev(X)) --> unop X
      if (match(Vec, m_OneUse(m_UnOp(
                         m_Intrinsic<Intrinsic::experimental_vector_reverse>(
                             m_Value(X)))))) {
        auto *OldUnOp = cast<UnaryOperator>(Vec);
        auto *NewUnOp = UnaryOperator::CreateWithCopiedFlags(
            OldUnOp->getOpcode(), X, OldUnOp, OldUnOp->getName(), II);
        return replaceInstUsesWith(CI, NewUnOp);
      }
      break;
    }
    case Intrinsic::vector_reduce_or:
    case Intrinsic::vector_reduce_and: {
      // Canonicalize logical or/and reductions:
      // Or reduction for i1 is represented as:
      // %val = bitcast <ReduxWidth x i1> to iReduxWidth
      // %res = cmp ne iReduxWidth %val, 0
      // And reduction for i1 is represented as:
      // %val = bitcast <ReduxWidth x i1> to iReduxWidth
      // %res = cmp eq iReduxWidth %val, 11111
      Value *Arg = II->getArgOperand(0);
      Value *Vect;
      if (match(Arg, m_ZExtOrSExtOrSelf(m_Value(Vect)))) {
        if (auto *FTy = dyn_cast<FixedVectorType>(Vect->getType()))
          if (FTy->getElementType() == Builder.getInt1Ty()) {
            Value *Res = Builder.CreateBitCast(
                Vect, Builder.getIntNTy(FTy->getNumElements()));
            if (IID == Intrinsic::vector_reduce_and) {
              Res = Builder.CreateICmpEQ(
                  Res, ConstantInt::getAllOnesValue(Res->getType()));
            } else {
              assert(IID == Intrinsic::vector_reduce_or &&
                     "Expected or reduction.");
              Res = Builder.CreateIsNotNull(Res);
            }
            if (Arg != Vect)
              Res = Builder.CreateCast(cast<CastInst>(Arg)->getOpcode(), Res,
                                       II->getType());
            return replaceInstUsesWith(CI, Res);
          }
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::vector_reduce_add: {
      if (IID == Intrinsic::vector_reduce_add) {
        // Convert vector_reduce_add(ZExt(<n x i1>)) to
        // ZExtOrTrunc(ctpop(bitcast <n x i1> to in)).
        // Convert vector_reduce_add(SExt(<n x i1>)) to
        // -ZExtOrTrunc(ctpop(bitcast <n x i1> to in)).
        // Convert vector_reduce_add(<n x i1>) to
        // Trunc(ctpop(bitcast <n x i1> to in)).
        Value *Arg = II->getArgOperand(0);
        Value *Vect;
        if (match(Arg, m_ZExtOrSExtOrSelf(m_Value(Vect)))) {
          if (auto *FTy = dyn_cast<FixedVectorType>(Vect->getType()))
            if (FTy->getElementType() == Builder.getInt1Ty()) {
              Value *V = Builder.CreateBitCast(
                  Vect, Builder.getIntNTy(FTy->getNumElements()));
              Value *Res = Builder.CreateUnaryIntrinsic(Intrinsic::ctpop, V);
              if (Res->getType() != II->getType())
                Res = Builder.CreateZExtOrTrunc(Res, II->getType());
              if (Arg != Vect &&
                  cast<Instruction>(Arg)->getOpcode() == Instruction::SExt)
                Res = Builder.CreateNeg(Res);
              return replaceInstUsesWith(CI, Res);
            }
        }
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::vector_reduce_xor: {
      if (IID == Intrinsic::vector_reduce_xor) {
        // Exclusive disjunction reduction over the vector with
        // (potentially-extended) i1 element type is actually a
        // (potentially-extended) arithmetic `add` reduction over the original
        // non-extended value:
        //   vector_reduce_xor(?ext(<n x i1>))
        //     -->
        //   ?ext(vector_reduce_add(<n x i1>))
        Value *Arg = II->getArgOperand(0);
        Value *Vect;
        if (match(Arg, m_ZExtOrSExtOrSelf(m_Value(Vect)))) {
          if (auto *FTy = dyn_cast<FixedVectorType>(Vect->getType()))
            if (FTy->getElementType() == Builder.getInt1Ty()) {
              Value *Res = Builder.CreateAddReduce(Vect);
              if (Arg != Vect)
                Res = Builder.CreateCast(cast<CastInst>(Arg)->getOpcode(), Res,
                                         II->getType());
              return replaceInstUsesWith(CI, Res);
            }
        }
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::vector_reduce_mul: {
      if (IID == Intrinsic::vector_reduce_mul) {
        // Multiplicative reduction over the vector with (potentially-extended)
        // i1 element type is actually a (potentially zero-extended)
        // logical `and` reduction over the original non-extended value:
        //   vector_reduce_mul(?ext(<n x i1>))
        //     -->
        //   zext(vector_reduce_and(<n x i1>))
        Value *Arg = II->getArgOperand(0);
        Value *Vect;
        if (match(Arg, m_ZExtOrSExtOrSelf(m_Value(Vect)))) {
          if (auto *FTy = dyn_cast<FixedVectorType>(Vect->getType()))
            if (FTy->getElementType() == Builder.getInt1Ty()) {
              Value *Res = Builder.CreateAndReduce(Vect);
              if (Res->getType() != II->getType())
                Res = Builder.CreateZExt(Res, II->getType());
              return replaceInstUsesWith(CI, Res);
            }
        }
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::vector_reduce_umin:
    case Intrinsic::vector_reduce_umax: {
      if (IID == Intrinsic::vector_reduce_umin ||
          IID == Intrinsic::vector_reduce_umax) {
        // UMin/UMax reduction over the vector with (potentially-extended)
        // i1 element type is actually a (potentially-extended)
        // logical `and`/`or` reduction over the original non-extended value:
        //   vector_reduce_u{min,max}(?ext(<n x i1>))
        //     -->
        //   ?ext(vector_reduce_{and,or}(<n x i1>))
        Value *Arg = II->getArgOperand(0);
        Value *Vect;
        if (match(Arg, m_ZExtOrSExtOrSelf(m_Value(Vect)))) {
          if (auto *FTy = dyn_cast<FixedVectorType>(Vect->getType()))
            if (FTy->getElementType() == Builder.getInt1Ty()) {
              Value *Res = IID == Intrinsic::vector_reduce_umin
                               ? Builder.CreateAndReduce(Vect)
                               : Builder.CreateOrReduce(Vect);
              if (Arg != Vect)
                Res = Builder.CreateCast(cast<CastInst>(Arg)->getOpcode(), Res,
                                         II->getType());
              return replaceInstUsesWith(CI, Res);
            }
        }
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::vector_reduce_smin:
    case Intrinsic::vector_reduce_smax: {
      if (IID == Intrinsic::vector_reduce_smin ||
          IID == Intrinsic::vector_reduce_smax) {
        // SMin/SMax reduction over the vector with (potentially-extended)
        // i1 element type is actually a (potentially-extended)
        // logical `and`/`or` reduction over the original non-extended value:
        //   vector_reduce_s{min,max}(<n x i1>)
        //     -->
        //   vector_reduce_{or,and}(<n x i1>)
        // and
        //   vector_reduce_s{min,max}(sext(<n x i1>))
        //     -->
        //   sext(vector_reduce_{or,and}(<n x i1>))
        // and
        //   vector_reduce_s{min,max}(zext(<n x i1>))
        //     -->
        //   zext(vector_reduce_{and,or}(<n x i1>))
        Value *Arg = II->getArgOperand(0);
        Value *Vect;
        if (match(Arg, m_ZExtOrSExtOrSelf(m_Value(Vect)))) {
          if (auto *FTy = dyn_cast<FixedVectorType>(Vect->getType()))
            if (FTy->getElementType() == Builder.getInt1Ty()) {
              Instruction::CastOps ExtOpc = Instruction::CastOps::CastOpsEnd;
              if (Arg != Vect)
                ExtOpc = cast<CastInst>(Arg)->getOpcode();
              Value *Res = ((IID == Intrinsic::vector_reduce_smin) ==
                            (ExtOpc == Instruction::CastOps::ZExt))
                               ? Builder.CreateAndReduce(Vect)
                               : Builder.CreateOrReduce(Vect);
              if (Arg != Vect)
                Res = Builder.CreateCast(ExtOpc, Res, II->getType());
              return replaceInstUsesWith(CI, Res);
            }
        }
      }
      LLVM_FALLTHROUGH;
    }
    case Intrinsic::vector_reduce_fmax:
    case Intrinsic::vector_reduce_fmin:
    case Intrinsic::vector_reduce_fadd:
    case Intrinsic::vector_reduce_fmul: {
      bool CanBeReassociated = (IID != Intrinsic::vector_reduce_fadd &&
                                IID != Intrinsic::vector_reduce_fmul) ||
                               II->hasAllowReassoc();
      const unsigned ArgIdx = (IID == Intrinsic::vector_reduce_fadd ||
                               IID == Intrinsic::vector_reduce_fmul)
                                  ? 1
                                  : 0;
      Value *Arg = II->getArgOperand(ArgIdx);
      Value *V;
      ArrayRef<int> Mask;
      if (!isa<FixedVectorType>(Arg->getType()) || !CanBeReassociated ||
          !match(Arg, m_Shuffle(m_Value(V), m_Undef(), m_Mask(Mask))) ||
          !cast<ShuffleVectorInst>(Arg)->isSingleSource())
        break;
      int Sz = Mask.size();
      SmallBitVector UsedIndices(Sz);
      for (int Idx : Mask) {
        if (Idx == UndefMaskElem || UsedIndices.test(Idx))
          break;
        UsedIndices.set(Idx);
      }
      // Can remove shuffle iff just shuffled elements, no repeats, undefs, or
      // other changes.
      if (UsedIndices.all()) {
        replaceUse(II->getOperandUse(ArgIdx), V);
        return nullptr;
      }
      break;
    }
    default: {
      // Handle target specific intrinsics
      Optional<Instruction *> V = targetInstCombineIntrinsic(*II);
      if (V.hasValue())
        return V.getValue();
      break;
    }
    }
    // Some intrinsics (like experimental_gc_statepoint) can be used in invoke
    // context, so it is handled in visitCallBase and we should trigger it.
    return visitCallBase(*II);
  }
  
  // Fence instruction simplification
  Instruction *InstCombinerImpl::visitFenceInst(FenceInst &FI) {
    auto *NFI = dyn_cast<FenceInst>(FI.getNextNonDebugInstruction());
    // This check is solely here to handle arbitrary target-dependent syncscopes.
    // TODO: Can remove if does not matter in practice.
    if (NFI && FI.isIdenticalTo(NFI))
      return eraseInstFromFunction(FI);
  
    // Returns true if FI1 is identical or stronger fence than FI2.
    auto isIdenticalOrStrongerFence = [](FenceInst *FI1, FenceInst *FI2) {
      auto FI1SyncScope = FI1->getSyncScopeID();
      // Consider same scope, where scope is global or single-thread.
      if (FI1SyncScope != FI2->getSyncScopeID() ||
          (FI1SyncScope != SyncScope::System &&
           FI1SyncScope != SyncScope::SingleThread))
        return false;
  
      return isAtLeastOrStrongerThan(FI1->getOrdering(), FI2->getOrdering());
    };
    if (NFI && isIdenticalOrStrongerFence(NFI, &FI))
      return eraseInstFromFunction(FI);
  
    if (auto *PFI = dyn_cast_or_null<FenceInst>(FI.getPrevNonDebugInstruction()))
      if (isIdenticalOrStrongerFence(PFI, &FI))
        return eraseInstFromFunction(FI);
    return nullptr;
  }
  
  // InvokeInst simplification
  Instruction *InstCombinerImpl::visitInvokeInst(InvokeInst &II) {
    return visitCallBase(II);
  }
  
  // CallBrInst simplification
  Instruction *InstCombinerImpl::visitCallBrInst(CallBrInst &CBI) {
    return visitCallBase(CBI);
  }
  
  /// 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 CallBase &Call,
                                           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 (isa<GCStatepointInst>(Call) || isa<GCRelocateInst>(Call) ||
        isa<GCResultInst>(Call))
      return false;
  
    // Opaque pointers are compatible with any byval types.
    PointerType *SrcTy = cast<PointerType>(CI->getOperand(0)->getType());
    if (SrcTy->isOpaque())
      return true;
  
    // 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 (!Call.isPassPointeeByValueArgument(ix))
      return true;
  
    // The transform currently only handles type replacement for byval, not other
    // type-carrying attributes.
    if (!Call.isByValArgument(ix))
      return false;
  
    Type *SrcElemTy = SrcTy->getNonOpaquePointerElementType();
    Type *DstElemTy = Call.getParamByValType(ix);
    if (!SrcElemTy->isSized() || !DstElemTy->isSized())
      return false;
    if (DL.getTypeAllocSize(SrcElemTy) != DL.getTypeAllocSize(DstElemTy))
      return false;
    return true;
  }
  
  Instruction *InstCombinerImpl::tryOptimizeCall(CallInst *CI) {
    if (!CI->getCalledFunction()) return nullptr;
  
    // Skip optimizing notail and musttail calls so
    // LibCallSimplifier::optimizeCall doesn't have to preserve those invariants.
    // LibCallSimplifier::optimizeCall should try to preseve tail calls though.
    if (CI->isMustTailCall() || CI->isNoTailCall())
      return nullptr;
  
    auto InstCombineRAUW = [this](Instruction *From, Value *With) {
      replaceInstUsesWith(*From, With);
    };
    auto InstCombineErase = [this](Instruction *I) {
      eraseInstFromFunction(*I);
    };
    LibCallSimplifier Simplifier(DL, &TLI, ORE, BFI, PSI, InstCombineRAUW,
                                 InstCombineErase);
    if (Value *With = Simplifier.optimizeCall(CI, Builder)) {
      ++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;
  }
  
  void InstCombinerImpl::annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI) {
    // Note: We only handle cases which can't be driven from generic attributes
    // here.  So, for example, nonnull and noalias (which are common properties
    // of some allocation functions) are expected to be handled via annotation
    // of the respective allocator declaration with generic attributes.
  
    uint64_t Size;
    ObjectSizeOpts Opts;
    if (getObjectSize(&Call, Size, DL, TLI, Opts) && Size > 0) {
      // TODO: We really should just emit deref_or_null here and then
      // let the generic inference code combine that with nonnull.
      if (Call.hasRetAttr(Attribute::NonNull))
        Call.addRetAttr(Attribute::getWithDereferenceableBytes(
            Call.getContext(), Size));
      else
        Call.addRetAttr(Attribute::getWithDereferenceableOrNullBytes(
            Call.getContext(), Size));
    }
  
    // Add alignment attribute if alignment is a power of two constant.
    Value *Alignment = getAllocAlignment(&Call, TLI);
    if (!Alignment)
      return;
  
    ConstantInt *AlignOpC = dyn_cast<ConstantInt>(Alignment);
    if (AlignOpC && AlignOpC->getValue().ult(llvm::Value::MaximumAlignment)) {
      uint64_t AlignmentVal = AlignOpC->getZExtValue();
      if (llvm::isPowerOf2_64(AlignmentVal)) {
        Call.removeRetAttr(Attribute::Alignment);
        Call.addRetAttr(Attribute::getWithAlignment(Call.getContext(),
                                                    Align(AlignmentVal)));
      }
    }
  }
  
  /// Improvements for call, callbr and invoke instructions.
  Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
    if (isAllocationFn(&Call, &TLI))
      annotateAnyAllocSite(Call, &TLI);
  
    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> ArgNos;
    unsigned ArgNo = 0;
  
    for (Value *V : Call.args()) {
      if (V->getType()->isPointerTy() &&
          !Call.paramHasAttr(ArgNo, Attribute::NonNull) &&
          isKnownNonZero(V, DL, 0, &AC, &Call, &DT))
        ArgNos.push_back(ArgNo);
      ArgNo++;
    }
  
    assert(ArgNo == Call.arg_size() && "Call arguments not processed correctly.");
  
    if (!ArgNos.empty()) {
      AttributeList AS = Call.getAttributes();
      LLVMContext &Ctx = Call.getContext();
      AS = AS.addParamAttribute(Ctx, ArgNos,
                                Attribute::get(Ctx, Attribute::NonNull));
      Call.setAttributes(AS);
      Changed = true;
    }
  
    // If the callee is a pointer to a function, attempt to move any casts to the
    // arguments of the call/callbr/invoke.
    Value *Callee = Call.getCalledOperand();
    if (!isa<Function>(Callee) && transformConstExprCastCall(Call))
      return nullptr;
  
    if (Function *CalleeF = dyn_cast<Function>(Callee)) {
      // Remove the convergent attr on calls when the callee is not convergent.
      if (Call.isConvergent() && !CalleeF->isConvergent() &&
          !CalleeF->isIntrinsic()) {
        LLVM_DEBUG(dbgs() << "Removing convergent attr from instr " << Call
                          << "\n");
        Call.setNotConvergent();
        return &Call;
      }
  
      // If the call and callee calling conventions don't match, and neither one
      // of the calling conventions is compatible with C calling convention
      // this call must be unreachable, as the call is undefined.
      if ((CalleeF->getCallingConv() != Call.getCallingConv() &&
           !(CalleeF->getCallingConv() == llvm::CallingConv::C &&
             TargetLibraryInfoImpl::isCallingConvCCompatible(&Call)) &&
           !(Call.getCallingConv() == llvm::CallingConv::C &&
             TargetLibraryInfoImpl::isCallingConvCCompatible(CalleeF))) &&
          // 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 = &Call;
        CreateNonTerminatorUnreachable(OldCall);
        // If OldCall does not return void then replaceInstUsesWith poison.
        // This allows ValueHandlers and custom metadata to adjust itself.
        if (!OldCall->getType()->isVoidTy())
          replaceInstUsesWith(*OldCall, PoisonValue::get(OldCall->getType()));
        if (isa<CallInst>(OldCall))
          return eraseInstFromFunction(*OldCall);
  
        // We cannot remove an invoke or a callbr, because it would change thexi
        // CFG, just change the callee to a null pointer.
        cast<CallBase>(OldCall)->setCalledFunction(
            CalleeF->getFunctionType(),
            Constant::getNullValue(CalleeF->getType()));
        return nullptr;
      }
    }
  
    // Calling a null function pointer is undefined if a null address isn't
    // dereferenceable.
    if ((isa<ConstantPointerNull>(Callee) &&
         !NullPointerIsDefined(Call.getFunction())) ||
        isa<UndefValue>(Callee)) {
      // If Call does not return void then replaceInstUsesWith poison.
      // This allows ValueHandlers and custom metadata to adjust itself.
      if (!Call.getType()->isVoidTy())
        replaceInstUsesWith(Call, PoisonValue::get(Call.getType()));
  
      if (Call.isTerminator()) {
        // Can't remove an invoke or callbr because we cannot change the CFG.
        return nullptr;
      }
  
      // This instruction is not reachable, just remove it.
      CreateNonTerminatorUnreachable(&Call);
      return eraseInstFromFunction(Call);
    }
  
    if (IntrinsicInst *II = findInitTrampoline(Callee))
      return transformCallThroughTrampoline(Call, *II);
  
    // TODO: Drop this transform once opaque pointer transition is done.
    FunctionType *FTy = Call.getFunctionType();
    if (FTy->isVarArg()) {
      int ix = FTy->getNumParams();
      // See if we can optimize any arguments passed through the varargs area of
      // the call.
      for (auto I = Call.arg_begin() + FTy->getNumParams(), E = Call.arg_end();
           I != E; ++I, ++ix) {
        CastInst *CI = dyn_cast<CastInst>(*I);
        if (CI && isSafeToEliminateVarargsCast(Call, DL, CI, ix)) {
          replaceUse(*I, CI->getOperand(0));
  
          // Update the byval type to match the pointer type.
          // Not necessary for opaque pointers.
          PointerType *NewTy = cast<PointerType>(CI->getOperand(0)->getType());
          if (!NewTy->isOpaque() && Call.isByValArgument(ix)) {
            Call.removeParamAttr(ix, Attribute::ByVal);
            Call.addParamAttr(ix, Attribute::getWithByValType(
                                      Call.getContext(),
                                      NewTy->getNonOpaquePointerElementType()));
          }
          Changed = true;
        }
      }
    }
  
    if (isa<InlineAsm>(Callee) && !Call.doesNotThrow()) {
      InlineAsm *IA = cast<InlineAsm>(Callee);
      if (!IA->canThrow()) {
        // Normal inline asm calls cannot throw - mark them
        // 'nounwind'.
        Call.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>(&Call)) {
      Instruction *I = tryOptimizeCall(CI);
      // If we changed something return the result, etc. Otherwise let
      // the fallthrough check.
      if (I) return eraseInstFromFunction(*I);
    }
  
    if (!Call.use_empty() && !Call.isMustTailCall())
      if (Value *ReturnedArg = Call.getReturnedArgOperand()) {
        Type *CallTy = Call.getType();
        Type *RetArgTy = ReturnedArg->getType();
        if (RetArgTy->canLosslesslyBitCastTo(CallTy))
          return replaceInstUsesWith(
              Call, Builder.CreateBitOrPointerCast(ReturnedArg, CallTy));
      }
  
    if (isAllocationFn(&Call, &TLI) &&
        isAllocRemovable(&cast<CallBase>(Call), &TLI))
      return visitAllocSite(Call);
  
    // Handle intrinsics which can be used in both call and invoke context.
    switch (Call.getIntrinsicID()) {
    case Intrinsic::experimental_gc_statepoint: {
      GCStatepointInst &GCSP = *cast<GCStatepointInst>(&Call);
      SmallPtrSet<Value *, 32> LiveGcValues;
      for (const GCRelocateInst *Reloc : GCSP.getGCRelocates()) {
        GCRelocateInst &GCR = *const_cast<GCRelocateInst *>(Reloc);
  
        // Remove the relocation if unused.
        if (GCR.use_empty()) {
          eraseInstFromFunction(GCR);
          continue;
        }
  
        Value *DerivedPtr = GCR.getDerivedPtr();
        Value *BasePtr = GCR.getBasePtr();
  
        // Undef is undef, even after relocation.
        if (isa<UndefValue>(DerivedPtr) || isa<UndefValue>(BasePtr)) {
          replaceInstUsesWith(GCR, UndefValue::get(GCR.getType()));
          eraseInstFromFunction(GCR);
          continue;
        }
  
        if (auto *PT = dyn_cast<PointerType>(GCR.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.
            replaceInstUsesWith(GCR, ConstantPointerNull::get(PT));
            eraseInstFromFunction(GCR);
            continue;
          }
  
          // isKnownNonNull -> nonnull attribute
          if (!GCR.hasRetAttr(Attribute::NonNull) &&
              isKnownNonZero(DerivedPtr, DL, 0, &AC, &Call, &DT)) {
            GCR.addRetAttr(Attribute::NonNull);
            // We discovered new fact, re-check users.
            Worklist.pushUsersToWorkList(GCR);
          }
        }
  
        // If we have two copies of the same pointer in the statepoint argument
        // list, canonicalize to one.  This may let us common gc.relocates.
        if (GCR.getBasePtr() == GCR.getDerivedPtr() &&
            GCR.getBasePtrIndex() != GCR.getDerivedPtrIndex()) {
          auto *OpIntTy = GCR.getOperand(2)->getType();
          GCR.setOperand(2, ConstantInt::get(OpIntTy, GCR.getBasePtrIndex()));
        }
  
        // 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, ...)
        LiveGcValues.insert(BasePtr);
        LiveGcValues.insert(DerivedPtr);
      }
      Optional<OperandBundleUse> Bundle =
          GCSP.getOperandBundle(LLVMContext::OB_gc_live);
      unsigned NumOfGCLives = LiveGcValues.size();
      if (!Bundle.hasValue() || NumOfGCLives == Bundle->Inputs.size())
        break;
      // We can reduce the size of gc live bundle.
      DenseMap<Value *, unsigned> Val2Idx;
      std::vector<Value *> NewLiveGc;
      for (unsigned I = 0, E = Bundle->Inputs.size(); I < E; ++I) {
        Value *V = Bundle->Inputs[I];
        if (Val2Idx.count(V))
          continue;
        if (LiveGcValues.count(V)) {
          Val2Idx[V] = NewLiveGc.size();
          NewLiveGc.push_back(V);
        } else
          Val2Idx[V] = NumOfGCLives;
      }
      // Update all gc.relocates
      for (const GCRelocateInst *Reloc : GCSP.getGCRelocates()) {
        GCRelocateInst &GCR = *const_cast<GCRelocateInst *>(Reloc);
        Value *BasePtr = GCR.getBasePtr();
        assert(Val2Idx.count(BasePtr) && Val2Idx[BasePtr] != NumOfGCLives &&
               "Missed live gc for base pointer");
        auto *OpIntTy1 = GCR.getOperand(1)->getType();
        GCR.setOperand(1, ConstantInt::get(OpIntTy1, Val2Idx[BasePtr]));
        Value *DerivedPtr = GCR.getDerivedPtr();
        assert(Val2Idx.count(DerivedPtr) && Val2Idx[DerivedPtr] != NumOfGCLives &&
               "Missed live gc for derived pointer");
        auto *OpIntTy2 = GCR.getOperand(2)->getType();
        GCR.setOperand(2, ConstantInt::get(OpIntTy2, Val2Idx[DerivedPtr]));
      }
      // Create new statepoint instruction.
      OperandBundleDef NewBundle("gc-live", NewLiveGc);
      return CallBase::Create(&Call, NewBundle);
    }
    default: { break; }
    }
  
    return Changed ? &Call : nullptr;
  }
  
  /// If the callee is a constexpr cast of a function, attempt to move the cast to
  /// the arguments of the call/callbr/invoke.
  bool InstCombinerImpl::transformConstExprCastCall(CallBase &Call) {
    auto *Callee =
        dyn_cast<Function>(Call.getCalledOperand()->stripPointerCasts());
    if (!Callee)
      return false;
  
    // If this is a call to a thunk function, don't remove the cast. Thunks are
    // used to transparently forward all incoming parameters and outgoing return
    // values, so it's important to leave the cast in place.
    if (Callee->hasFnAttribute("thunk"))
      return false;
  
    // If this is a musttail call, the callee's prototype must match the caller's
    // prototype with the exception of pointee types. The code below doesn't
    // implement that, so we can't do this transform.
    // TODO: Do the transform if it only requires adding pointer casts.
    if (Call.isMustTailCall())
      return false;
  
    Instruction *Caller = &Call;
    const AttributeList &CallerPAL = Call.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(FT->getContext(), CallerPAL.getRetAttrs());
        if (RAttrs.overlaps(AttributeFuncs::typeIncompatible(NewRetTy)))
          return false;   // Attribute not compatible with transformed value.
      }
  
      // If the callbase is an invoke/callbr 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;
        // FIXME: Be conservative for callbr to avoid a quadratic search.
        if (isa<CallBrInst>(Caller))
          return false;
      }
    }
  
    unsigned NumActualArgs = Call.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::Preallocated) ||
        Callee->getAttributes().hasAttrSomewhere(Attribute::ByVal))
      return false;
  
    auto AI = Call.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(FT->getContext(), CallerPAL.getParamAttrs(i))
              .overlaps(AttributeFuncs::typeIncompatible(ParamTy)))
        return false;   // Attribute not compatible with transformed value.
  
      if (Call.isInAllocaArgument(i))
        return false;   // Cannot transform to and from inalloca.
  
      if (CallerPAL.hasParamAttr(i, Attribute::SwiftError))
        return false;
  
      // 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.hasParamAttr(i, Attribute::ByVal)) {
        PointerType *ParamPTy = dyn_cast<PointerType>(ParamTy);
        if (!ParamPTy || !ParamPTy->getPointerElementType()->isSized())
          return false;
  
        Type *CurElTy = Call.getParamByValType(i);
        if (DL.getTypeAllocSize(CurElTy) !=
            DL.getTypeAllocSize(ParamPTy->getPointerElementType()))
          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.
      if (FT->isVarArg() != Call.getFunctionType()->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() && Call.getFunctionType()->isVarArg() &&
          FT->getNumParams() != Call.getFunctionType()->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.
      unsigned SRetIdx;
      if (CallerPAL.hasAttrSomewhere(Attribute::StructRet, &SRetIdx) &&
          SRetIdx - AttributeList::FirstArgIndex >= FT->getNumParams())
        return false;
    }
  
    // Okay, we decided that this is a safe thing to do: go ahead and start
    // inserting cast instructions as necessary.
    SmallVector<Value *, 8> Args;
    SmallVector<AttributeSet, 8> ArgAttrs;
    Args.reserve(NumActualArgs);
    ArgAttrs.reserve(NumActualArgs);
  
    // Get any return attributes.
    AttrBuilder RAttrs(FT->getContext(), CallerPAL.getRetAttrs());
  
    // 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));
  
    LLVMContext &Ctx = Call.getContext();
    AI = Call.arg_begin();
    for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
      Type *ParamTy = FT->getParamType(i);
  
      Value *NewArg = *AI;
      if ((*AI)->getType() != ParamTy)
        NewArg = Builder.CreateBitOrPointerCast(*AI, ParamTy);
      Args.push_back(NewArg);
  
      // Add any parameter attributes.
      if (CallerPAL.hasParamAttr(i, Attribute::ByVal)) {
        AttrBuilder AB(FT->getContext(), CallerPAL.getParamAttrs(i));
        AB.addByValAttr(NewArg->getType()->getPointerElementType());
        ArgAttrs.push_back(AttributeSet::get(Ctx, AB));
      } else
        ArgAttrs.push_back(CallerPAL.getParamAttrs(i));
    }
  
    // 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)));
      ArgAttrs.push_back(AttributeSet());
    }
  
    // 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());
          Value *NewArg = *AI;
          if (PTy != (*AI)->getType()) {
            // Must promote to pass through va_arg area!
            Instruction::CastOps opcode =
              CastInst::getCastOpcode(*AI, false, PTy, false);
            NewArg = Builder.CreateCast(opcode, *AI, PTy);
          }
          Args.push_back(NewArg);
  
          // Add any parameter attributes.
          ArgAttrs.push_back(CallerPAL.getParamAttrs(i));
        }
      }
    }
  
    AttributeSet FnAttrs = CallerPAL.getFnAttrs();
  
    if (NewRetTy->isVoidTy())
      Caller->setName("");   // Void type should not have a name.
  
    assert((ArgAttrs.size() == FT->getNumParams() || FT->isVarArg()) &&
           "missing argument attributes");
    AttributeList NewCallerPAL = AttributeList::get(
        Ctx, FnAttrs, AttributeSet::get(Ctx, RAttrs), ArgAttrs);
  
    SmallVector<OperandBundleDef, 1> OpBundles;
    Call.getOperandBundlesAsDefs(OpBundles);
  
    CallBase *NewCall;
    if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
      NewCall = Builder.CreateInvoke(Callee, II->getNormalDest(),
                                     II->getUnwindDest(), Args, OpBundles);
    } else if (CallBrInst *CBI = dyn_cast<CallBrInst>(Caller)) {
      NewCall = Builder.CreateCallBr(Callee, CBI->getDefaultDest(),
                                     CBI->getIndirectDests(), Args, OpBundles);
    } else {
      NewCall = Builder.CreateCall(Callee, Args, OpBundles);
      cast<CallInst>(NewCall)->setTailCallKind(
          cast<CallInst>(Caller)->getTailCallKind());
    }
    NewCall->takeName(Caller);
    NewCall->setCallingConv(Call.getCallingConv());
    NewCall->setAttributes(NewCallerPAL);
  
    // Preserve prof metadata if any.
    NewCall->copyMetadata(*Caller, {LLVMContext::MD_prof});
  
    // Insert a cast of the return type as necessary.
    Instruction *NC = NewCall;
    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/callbr 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 if (CallBrInst *CBI = dyn_cast<CallBrInst>(Caller)) {
          BasicBlock::iterator I = CBI->getDefaultDest()->getFirstInsertionPt();
          InsertNewInstBefore(NC, *I);
        } else {
          // Otherwise, it's a call, just insert cast right after the call.
          InsertNewInstBefore(NC, *Caller);
        }
        Worklist.pushUsersToWorkList(*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 *
  InstCombinerImpl::transformCallThroughTrampoline(CallBase &Call,
                                                   IntrinsicInst &Tramp) {
    Value *Callee = Call.getCalledOperand();
    Type *CalleeTy = Callee->getType();
    FunctionType *FTy = Call.getFunctionType();
    AttributeList Attrs = Call.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;
  
    Function *NestF = cast<Function>(Tramp.getArgOperand(1)->stripPointerCasts());
    FunctionType *NestFTy = NestF->getFunctionType();
  
    AttributeList NestAttrs = NestF->getAttributes();
    if (!NestAttrs.isEmpty()) {
      unsigned NestArgNo = 0;
      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; ++NestArgNo, ++I) {
        AttributeSet AS = NestAttrs.getParamAttrs(NestArgNo);
        if (AS.hasAttribute(Attribute::Nest)) {
          // Record the parameter type and any other attributes.
          NestTy = *I;
          NestAttr = AS;
          break;
        }
      }
  
      if (NestTy) {
        std::vector<Value*> NewArgs;
        std::vector<AttributeSet> NewArgAttrs;
        NewArgs.reserve(Call.arg_size() + 1);
        NewArgAttrs.reserve(Call.arg_size());
  
        // Insert the nest argument into the call argument list, which may
        // mean appending it.  Likewise for attributes.
  
        {
          unsigned ArgNo = 0;
          auto I = Call.arg_begin(), E = Call.arg_end();
          do {
            if (ArgNo == NestArgNo) {
              // 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);
              NewArgAttrs.push_back(NestAttr);
            }
  
            if (I == E)
              break;
  
            // Add the original argument and attributes.
            NewArgs.push_back(*I);
            NewArgAttrs.push_back(Attrs.getParamAttrs(ArgNo));
  
            ++ArgNo;
            ++I;
          } while (true);
        }
  
        // 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 ArgNo = 0;
          FunctionType::param_iterator I = FTy->param_begin(),
            E = FTy->param_end();
  
          do {
            if (ArgNo == NestArgNo)
              // Add the chain's type.
              NewTypes.push_back(NestTy);
  
            if (I == E)
              break;
  
            // Add the original type.
            NewTypes.push_back(*I);
  
            ++ArgNo;
            ++I;
          } while (true);
        }
  
        // 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));
        AttributeList NewPAL =
            AttributeList::get(FTy->getContext(), Attrs.getFnAttrs(),
                               Attrs.getRetAttrs(), NewArgAttrs);
  
        SmallVector<OperandBundleDef, 1> OpBundles;
        Call.getOperandBundlesAsDefs(OpBundles);
  
        Instruction *NewCaller;
        if (InvokeInst *II = dyn_cast<InvokeInst>(&Call)) {
          NewCaller = InvokeInst::Create(NewFTy, NewCallee,
                                         II->getNormalDest(), II->getUnwindDest(),
                                         NewArgs, OpBundles);
          cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
          cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
        } else if (CallBrInst *CBI = dyn_cast<CallBrInst>(&Call)) {
          NewCaller =
              CallBrInst::Create(NewFTy, NewCallee, CBI->getDefaultDest(),
                                 CBI->getIndirectDests(), NewArgs, OpBundles);
          cast<CallBrInst>(NewCaller)->setCallingConv(CBI->getCallingConv());
          cast<CallBrInst>(NewCaller)->setAttributes(NewPAL);
        } else {
          NewCaller = CallInst::Create(NewFTy, NewCallee, NewArgs, OpBundles);
          cast<CallInst>(NewCaller)->setTailCallKind(
              cast<CallInst>(Call).getTailCallKind());
          cast<CallInst>(NewCaller)->setCallingConv(
              cast<CallInst>(Call).getCallingConv());
          cast<CallInst>(NewCaller)->setAttributes(NewPAL);
        }
        NewCaller->setDebugLoc(Call.getDebugLoc());
  
        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 = ConstantExpr::getBitCast(NestF, CalleeTy);
    Call.setCalledFunction(FTy, NewCallee);
    return &Call;
  }
  