Remove LLVM 8.0.1 files.

1 files changed, 0 insertions, 1633 deletions

diff --git a/gnu/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/gnu/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
deleted file mode 100644
index 76ab614090f..00000000000
--- a/gnu/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ /dev/null
@@ -1,1633 +0,0 @@
-//===- InstCombineLoadStoreAlloca.cpp -------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements the visit functions for load, store and alloca.
-//
-//===----------------------------------------------------------------------===//
-
-#include "InstCombineInternal.h"
-#include "llvm/ADT/MapVector.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Loads.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/IR/ConstantRange.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/DebugInfoMetadata.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/MDBuilder.h"
-#include "llvm/IR/PatternMatch.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-using namespace llvm;
-using namespace PatternMatch;
-
-#define DEBUG_TYPE "instcombine"
-
-STATISTIC(NumDeadStore,    "Number of dead stores eliminated");
-STATISTIC(NumGlobalCopies, "Number of allocas copied from constant global");
-
-/// pointsToConstantGlobal - Return true if V (possibly indirectly) points to
-/// some part of a constant global variable.  This intentionally only accepts
-/// constant expressions because we can't rewrite arbitrary instructions.
-static bool pointsToConstantGlobal(Value *V) {
-  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
-    return GV->isConstant();
-
-  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
-    if (CE->getOpcode() == Instruction::BitCast ||
-        CE->getOpcode() == Instruction::AddrSpaceCast ||
-        CE->getOpcode() == Instruction::GetElementPtr)
-      return pointsToConstantGlobal(CE->getOperand(0));
-  }
-  return false;
-}
-
-/// isOnlyCopiedFromConstantGlobal - Recursively walk the uses of a (derived)
-/// pointer to an alloca.  Ignore any reads of the pointer, return false if we
-/// see any stores or other unknown uses.  If we see pointer arithmetic, keep
-/// track of whether it moves the pointer (with IsOffset) but otherwise traverse
-/// the uses.  If we see a memcpy/memmove that targets an unoffseted pointer to
-/// the alloca, and if the source pointer is a pointer to a constant global, we
-/// can optimize this.
-static bool
-isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
-                               SmallVectorImpl<Instruction *> &ToDelete) {
-  // We track lifetime intrinsics as we encounter them.  If we decide to go
-  // ahead and replace the value with the global, this lets the caller quickly
-  // eliminate the markers.
-
-  SmallVector<std::pair<Value *, bool>, 35> ValuesToInspect;
-  ValuesToInspect.emplace_back(V, false);
-  while (!ValuesToInspect.empty()) {
-    auto ValuePair = ValuesToInspect.pop_back_val();
-    const bool IsOffset = ValuePair.second;
-    for (auto &U : ValuePair.first->uses()) {
-      auto *I = cast<Instruction>(U.getUser());
-
-      if (auto *LI = dyn_cast<LoadInst>(I)) {
-        // Ignore non-volatile loads, they are always ok.
-        if (!LI->isSimple()) return false;
-        continue;
-      }
-
-      if (isa<BitCastInst>(I) || isa<AddrSpaceCastInst>(I)) {
-        // If uses of the bitcast are ok, we are ok.
-        ValuesToInspect.emplace_back(I, IsOffset);
-        continue;
-      }
-      if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
-        // If the GEP has all zero indices, it doesn't offset the pointer. If it
-        // doesn't, it does.
-        ValuesToInspect.emplace_back(I, IsOffset || !GEP->hasAllZeroIndices());
-        continue;
-      }
-
-      if (auto CS = CallSite(I)) {
-        // If this is the function being called then we treat it like a load and
-        // ignore it.
-        if (CS.isCallee(&U))
-          continue;
-
-        unsigned DataOpNo = CS.getDataOperandNo(&U);
-        bool IsArgOperand = CS.isArgOperand(&U);
-
-        // Inalloca arguments are clobbered by the call.
-        if (IsArgOperand && CS.isInAllocaArgument(DataOpNo))
-          return false;
-
-        // If this is a readonly/readnone call site, then we know it is just a
-        // load (but one that potentially returns the value itself), so we can
-        // ignore it if we know that the value isn't captured.
-        if (CS.onlyReadsMemory() &&
-            (CS.getInstruction()->use_empty() || CS.doesNotCapture(DataOpNo)))
-          continue;
-
-        // If this is being passed as a byval argument, the caller is making a
-        // copy, so it is only a read of the alloca.
-        if (IsArgOperand && CS.isByValArgument(DataOpNo))
-          continue;
-      }
-
-      // Lifetime intrinsics can be handled by the caller.
-      if (I->isLifetimeStartOrEnd()) {
-        assert(I->use_empty() && "Lifetime markers have no result to use!");
-        ToDelete.push_back(I);
-        continue;
-      }
-
-      // If this is isn't our memcpy/memmove, reject it as something we can't
-      // handle.
-      MemTransferInst *MI = dyn_cast<MemTransferInst>(I);
-      if (!MI)
-        return false;
-
-      // If the transfer is using the alloca as a source of the transfer, then
-      // ignore it since it is a load (unless the transfer is volatile).
-      if (U.getOperandNo() == 1) {
-        if (MI->isVolatile()) return false;
-        continue;
-      }
-
-      // If we already have seen a copy, reject the second one.
-      if (TheCopy) return false;
-
-      // If the pointer has been offset from the start of the alloca, we can't
-      // safely handle this.
-      if (IsOffset) return false;
-
-      // If the memintrinsic isn't using the alloca as the dest, reject it.
-      if (U.getOperandNo() != 0) return false;
-
-      // If the source of the memcpy/move is not a constant global, reject it.
-      if (!pointsToConstantGlobal(MI->getSource()))
-        return false;
-
-      // Otherwise, the transform is safe.  Remember the copy instruction.
-      TheCopy = MI;
-    }
-  }
-  return true;
-}
-
-/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
-/// modified by a copy from a constant global.  If we can prove this, we can
-/// replace any uses of the alloca with uses of the global directly.
-static MemTransferInst *
-isOnlyCopiedFromConstantGlobal(AllocaInst *AI,
-                               SmallVectorImpl<Instruction *> &ToDelete) {
-  MemTransferInst *TheCopy = nullptr;
-  if (isOnlyCopiedFromConstantGlobal(AI, TheCopy, ToDelete))
-    return TheCopy;
-  return nullptr;
-}
-
-/// Returns true if V is dereferenceable for size of alloca.
-static bool isDereferenceableForAllocaSize(const Value *V, const AllocaInst *AI,
-                                           const DataLayout &DL) {
-  if (AI->isArrayAllocation())
-    return false;
-  uint64_t AllocaSize = DL.getTypeStoreSize(AI->getAllocatedType());
-  if (!AllocaSize)
-    return false;
-  return isDereferenceableAndAlignedPointer(V, AI->getAlignment(),
-                                            APInt(64, AllocaSize), DL);
-}
-
-static Instruction *simplifyAllocaArraySize(InstCombiner &IC, AllocaInst &AI) {
-  // Check for array size of 1 (scalar allocation).
-  if (!AI.isArrayAllocation()) {
-    // i32 1 is the canonical array size for scalar allocations.
-    if (AI.getArraySize()->getType()->isIntegerTy(32))
-      return nullptr;
-
-    // Canonicalize it.
-    Value *V = IC.Builder.getInt32(1);
-    AI.setOperand(0, V);
-    return &AI;
-  }
-
-  // Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1
-  if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
-    if (C->getValue().getActiveBits() <= 64) {
-      Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
-      AllocaInst *New = IC.Builder.CreateAlloca(NewTy, nullptr, AI.getName());
-      New->setAlignment(AI.getAlignment());
-
-      // Scan to the end of the allocation instructions, to skip over a block of
-      // allocas if possible...also skip interleaved debug info
-      //
-      BasicBlock::iterator It(New);
-      while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
-        ++It;
-
-      // Now that I is pointing to the first non-allocation-inst in the block,
-      // insert our getelementptr instruction...
-      //
-      Type *IdxTy = IC.getDataLayout().getIntPtrType(AI.getType());
-      Value *NullIdx = Constant::getNullValue(IdxTy);
-      Value *Idx[2] = {NullIdx, NullIdx};
-      Instruction *GEP =
-          GetElementPtrInst::CreateInBounds(New, Idx, New->getName() + ".sub");
-      IC.InsertNewInstBefore(GEP, *It);
-
-      // Now make everything use the getelementptr instead of the original
-      // allocation.
-      return IC.replaceInstUsesWith(AI, GEP);
-    }
-  }
-
-  if (isa<UndefValue>(AI.getArraySize()))
-    return IC.replaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
-
-  // Ensure that the alloca array size argument has type intptr_t, so that
-  // any casting is exposed early.
-  Type *IntPtrTy = IC.getDataLayout().getIntPtrType(AI.getType());
-  if (AI.getArraySize()->getType() != IntPtrTy) {
-    Value *V = IC.Builder.CreateIntCast(AI.getArraySize(), IntPtrTy, false);
-    AI.setOperand(0, V);
-    return &AI;
-  }
-
-  return nullptr;
-}
-
-namespace {
-// If I and V are pointers in different address space, it is not allowed to
-// use replaceAllUsesWith since I and V have different types. A
-// non-target-specific transformation should not use addrspacecast on V since
-// the two address space may be disjoint depending on target.
-//
-// This class chases down uses of the old pointer until reaching the load
-// instructions, then replaces the old pointer in the load instructions with
-// the new pointer. If during the chasing it sees bitcast or GEP, it will
-// create new bitcast or GEP with the new pointer and use them in the load
-// instruction.
-class PointerReplacer {
-public:
-  PointerReplacer(InstCombiner &IC) : IC(IC) {}
-  void replacePointer(Instruction &I, Value *V);
-
-private:
-  void findLoadAndReplace(Instruction &I);
-  void replace(Instruction *I);
-  Value *getReplacement(Value *I);
-
-  SmallVector<Instruction *, 4> Path;
-  MapVector<Value *, Value *> WorkMap;
-  InstCombiner &IC;
-};
-} // end anonymous namespace
-
-void PointerReplacer::findLoadAndReplace(Instruction &I) {
-  for (auto U : I.users()) {
-    auto *Inst = dyn_cast<Instruction>(&*U);
-    if (!Inst)
-      return;
-    LLVM_DEBUG(dbgs() << "Found pointer user: " << *U << '\n');
-    if (isa<LoadInst>(Inst)) {
-      for (auto P : Path)
-        replace(P);
-      replace(Inst);
-    } else if (isa<GetElementPtrInst>(Inst) || isa<BitCastInst>(Inst)) {
-      Path.push_back(Inst);
-      findLoadAndReplace(*Inst);
-      Path.pop_back();
-    } else {
-      return;
-    }
-  }
-}
-
-Value *PointerReplacer::getReplacement(Value *V) {
-  auto Loc = WorkMap.find(V);
-  if (Loc != WorkMap.end())
-    return Loc->second;
-  return nullptr;
-}
-
-void PointerReplacer::replace(Instruction *I) {
-  if (getReplacement(I))
-    return;
-
-  if (auto *LT = dyn_cast<LoadInst>(I)) {
-    auto *V = getReplacement(LT->getPointerOperand());
-    assert(V && "Operand not replaced");
-    auto *NewI = new LoadInst(V);
-    NewI->takeName(LT);
-    IC.InsertNewInstWith(NewI, *LT);
-    IC.replaceInstUsesWith(*LT, NewI);
-    WorkMap[LT] = NewI;
-  } else if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
-    auto *V = getReplacement(GEP->getPointerOperand());
-    assert(V && "Operand not replaced");
-    SmallVector<Value *, 8> Indices;
-    Indices.append(GEP->idx_begin(), GEP->idx_end());
-    auto *NewI = GetElementPtrInst::Create(
-        V->getType()->getPointerElementType(), V, Indices);
-    IC.InsertNewInstWith(NewI, *GEP);
-    NewI->takeName(GEP);
-    WorkMap[GEP] = NewI;
-  } else if (auto *BC = dyn_cast<BitCastInst>(I)) {
-    auto *V = getReplacement(BC->getOperand(0));
-    assert(V && "Operand not replaced");
-    auto *NewT = PointerType::get(BC->getType()->getPointerElementType(),
-                                  V->getType()->getPointerAddressSpace());
-    auto *NewI = new BitCastInst(V, NewT);
-    IC.InsertNewInstWith(NewI, *BC);
-    NewI->takeName(BC);
-    WorkMap[BC] = NewI;
-  } else {
-    llvm_unreachable("should never reach here");
-  }
-}
-
-void PointerReplacer::replacePointer(Instruction &I, Value *V) {
-#ifndef NDEBUG
-  auto *PT = cast<PointerType>(I.getType());
-  auto *NT = cast<PointerType>(V->getType());
-  assert(PT != NT && PT->getElementType() == NT->getElementType() &&
-         "Invalid usage");
-#endif
-  WorkMap[&I] = V;
-  findLoadAndReplace(I);
-}
-
-Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
-  if (auto *I = simplifyAllocaArraySize(*this, AI))
-    return I;
-
-  if (AI.getAllocatedType()->isSized()) {
-    // If the alignment is 0 (unspecified), assign it the preferred alignment.
-    if (AI.getAlignment() == 0)
-      AI.setAlignment(DL.getPrefTypeAlignment(AI.getAllocatedType()));
-
-    // Move all alloca's of zero byte objects to the entry block and merge them
-    // together.  Note that we only do this for alloca's, because malloc should
-    // allocate and return a unique pointer, even for a zero byte allocation.
-    if (DL.getTypeAllocSize(AI.getAllocatedType()) == 0) {
-      // For a zero sized alloca there is no point in doing an array allocation.
-      // This is helpful if the array size is a complicated expression not used
-      // elsewhere.
-      if (AI.isArrayAllocation()) {
-        AI.setOperand(0, ConstantInt::get(AI.getArraySize()->getType(), 1));
-        return &AI;
-      }
-
-      // Get the first instruction in the entry block.
-      BasicBlock &EntryBlock = AI.getParent()->getParent()->getEntryBlock();
-      Instruction *FirstInst = EntryBlock.getFirstNonPHIOrDbg();
-      if (FirstInst != &AI) {
-        // If the entry block doesn't start with a zero-size alloca then move
-        // this one to the start of the entry block.  There is no problem with
-        // dominance as the array size was forced to a constant earlier already.
-        AllocaInst *EntryAI = dyn_cast<AllocaInst>(FirstInst);
-        if (!EntryAI || !EntryAI->getAllocatedType()->isSized() ||
-            DL.getTypeAllocSize(EntryAI->getAllocatedType()) != 0) {
-          AI.moveBefore(FirstInst);
-          return &AI;
-        }
-
-        // If the alignment of the entry block alloca is 0 (unspecified),
-        // assign it the preferred alignment.
-        if (EntryAI->getAlignment() == 0)
-          EntryAI->setAlignment(
-              DL.getPrefTypeAlignment(EntryAI->getAllocatedType()));
-        // Replace this zero-sized alloca with the one at the start of the entry
-        // block after ensuring that the address will be aligned enough for both
-        // types.
-        unsigned MaxAlign = std::max(EntryAI->getAlignment(),
-                                     AI.getAlignment());
-        EntryAI->setAlignment(MaxAlign);
-        if (AI.getType() != EntryAI->getType())
-          return new BitCastInst(EntryAI, AI.getType());
-        return replaceInstUsesWith(AI, EntryAI);
-      }
-    }
-  }
-
-  if (AI.getAlignment()) {
-    // Check to see if this allocation is only modified by a memcpy/memmove from
-    // a constant global whose alignment is equal to or exceeds that of the
-    // allocation.  If this is the case, we can change all users to use
-    // the constant global instead.  This is commonly produced by the CFE by
-    // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
-    // is only subsequently read.
-    SmallVector<Instruction *, 4> ToDelete;
-    if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(&AI, ToDelete)) {
-      unsigned SourceAlign = getOrEnforceKnownAlignment(
-          Copy->getSource(), AI.getAlignment(), DL, &AI, &AC, &DT);
-      if (AI.getAlignment() <= SourceAlign &&
-          isDereferenceableForAllocaSize(Copy->getSource(), &AI, DL)) {
-        LLVM_DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
-        LLVM_DEBUG(dbgs() << "  memcpy = " << *Copy << '\n');
-        for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
-          eraseInstFromFunction(*ToDelete[i]);
-        Constant *TheSrc = cast<Constant>(Copy->getSource());
-        auto *SrcTy = TheSrc->getType();
-        auto *DestTy = PointerType::get(AI.getType()->getPointerElementType(),
-                                        SrcTy->getPointerAddressSpace());
-        Constant *Cast =
-            ConstantExpr::getPointerBitCastOrAddrSpaceCast(TheSrc, DestTy);
-        if (AI.getType()->getPointerAddressSpace() ==
-            SrcTy->getPointerAddressSpace()) {
-          Instruction *NewI = replaceInstUsesWith(AI, Cast);
-          eraseInstFromFunction(*Copy);
-          ++NumGlobalCopies;
-          return NewI;
-        } else {
-          PointerReplacer PtrReplacer(*this);
-          PtrReplacer.replacePointer(AI, Cast);
-          ++NumGlobalCopies;
-        }
-      }
-    }
-  }
-
-  // At last, use the generic allocation site handler to aggressively remove
-  // unused allocas.
-  return visitAllocSite(AI);
-}
-
-// Are we allowed to form a atomic load or store of this type?
-static bool isSupportedAtomicType(Type *Ty) {
-  return Ty->isIntOrPtrTy() || Ty->isFloatingPointTy();
-}
-
-/// Helper to combine a load to a new type.
-///
-/// This just does the work of combining a load to a new type. It handles
-/// metadata, etc., and returns the new instruction. The \c NewTy should be the
-/// loaded *value* type. This will convert it to a pointer, cast the operand to
-/// that pointer type, load it, etc.
-///
-/// Note that this will create all of the instructions with whatever insert
-/// point the \c InstCombiner currently is using.
-static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewTy,
-                                      const Twine &Suffix = "") {
-  assert((!LI.isAtomic() || isSupportedAtomicType(NewTy)) &&
-         "can't fold an atomic load to requested type");
-
-  Value *Ptr = LI.getPointerOperand();
-  unsigned AS = LI.getPointerAddressSpace();
-  SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
-  LI.getAllMetadata(MD);
-
-  Value *NewPtr = nullptr;
-  if (!(match(Ptr, m_BitCast(m_Value(NewPtr))) &&
-        NewPtr->getType()->getPointerElementType() == NewTy &&
-        NewPtr->getType()->getPointerAddressSpace() == AS))
-    NewPtr = IC.Builder.CreateBitCast(Ptr, NewTy->getPointerTo(AS));
-
-  LoadInst *NewLoad = IC.Builder.CreateAlignedLoad(
-      NewPtr, LI.getAlignment(), LI.isVolatile(), LI.getName() + Suffix);
-  NewLoad->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
-  MDBuilder MDB(NewLoad->getContext());
-  for (const auto &MDPair : MD) {
-    unsigned ID = MDPair.first;
-    MDNode *N = MDPair.second;
-    // Note, essentially every kind of metadata should be preserved here! This
-    // routine is supposed to clone a load instruction changing *only its type*.
-    // The only metadata it makes sense to drop is metadata which is invalidated
-    // when the pointer type changes. This should essentially never be the case
-    // in LLVM, but we explicitly switch over only known metadata to be
-    // conservatively correct. If you are adding metadata to LLVM which pertains
-    // to loads, you almost certainly want to add it here.
-    switch (ID) {
-    case LLVMContext::MD_dbg:
-    case LLVMContext::MD_tbaa:
-    case LLVMContext::MD_prof:
-    case LLVMContext::MD_fpmath:
-    case LLVMContext::MD_tbaa_struct:
-    case LLVMContext::MD_invariant_load:
-    case LLVMContext::MD_alias_scope:
-    case LLVMContext::MD_noalias:
-    case LLVMContext::MD_nontemporal:
-    case LLVMContext::MD_mem_parallel_loop_access:
-    case LLVMContext::MD_access_group:
-      // All of these directly apply.
-      NewLoad->setMetadata(ID, N);
-      break;
-
-    case LLVMContext::MD_nonnull:
-      copyNonnullMetadata(LI, N, *NewLoad);
-      break;
-    case LLVMContext::MD_align:
-    case LLVMContext::MD_dereferenceable:
-    case LLVMContext::MD_dereferenceable_or_null:
-      // These only directly apply if the new type is also a pointer.
-      if (NewTy->isPointerTy())
-        NewLoad->setMetadata(ID, N);
-      break;
-    case LLVMContext::MD_range:
-      copyRangeMetadata(IC.getDataLayout(), LI, N, *NewLoad);
-      break;
-    }
-  }
-  return NewLoad;
-}
-
-/// Combine a store to a new type.
-///
-/// Returns the newly created store instruction.
-static StoreInst *combineStoreToNewValue(InstCombiner &IC, StoreInst &SI, Value *V) {
-  assert((!SI.isAtomic() || isSupportedAtomicType(V->getType())) &&
-         "can't fold an atomic store of requested type");
-
-  Value *Ptr = SI.getPointerOperand();
-  unsigned AS = SI.getPointerAddressSpace();
-  SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
-  SI.getAllMetadata(MD);
-
-  StoreInst *NewStore = IC.Builder.CreateAlignedStore(
-      V, IC.Builder.CreateBitCast(Ptr, V->getType()->getPointerTo(AS)),
-      SI.getAlignment(), SI.isVolatile());
-  NewStore->setAtomic(SI.getOrdering(), SI.getSyncScopeID());
-  for (const auto &MDPair : MD) {
-    unsigned ID = MDPair.first;
-    MDNode *N = MDPair.second;
-    // Note, essentially every kind of metadata should be preserved here! This
-    // routine is supposed to clone a store instruction changing *only its
-    // type*. The only metadata it makes sense to drop is metadata which is
-    // invalidated when the pointer type changes. This should essentially
-    // never be the case in LLVM, but we explicitly switch over only known
-    // metadata to be conservatively correct. If you are adding metadata to
-    // LLVM which pertains to stores, you almost certainly want to add it
-    // here.
-    switch (ID) {
-    case LLVMContext::MD_dbg:
-    case LLVMContext::MD_tbaa:
-    case LLVMContext::MD_prof:
-    case LLVMContext::MD_fpmath:
-    case LLVMContext::MD_tbaa_struct:
-    case LLVMContext::MD_alias_scope:
-    case LLVMContext::MD_noalias:
-    case LLVMContext::MD_nontemporal:
-    case LLVMContext::MD_mem_parallel_loop_access:
-    case LLVMContext::MD_access_group:
-      // All of these directly apply.
-      NewStore->setMetadata(ID, N);
-      break;
-    case LLVMContext::MD_invariant_load:
-    case LLVMContext::MD_nonnull:
-    case LLVMContext::MD_range:
-    case LLVMContext::MD_align:
-    case LLVMContext::MD_dereferenceable:
-    case LLVMContext::MD_dereferenceable_or_null:
-      // These don't apply for stores.
-      break;
-    }
-  }
-
-  return NewStore;
-}
-
-/// Returns true if instruction represent minmax pattern like:
-///   select ((cmp load V1, load V2), V1, V2).
-static bool isMinMaxWithLoads(Value *V) {
-  assert(V->getType()->isPointerTy() && "Expected pointer type.");
-  // Ignore possible ty* to ixx* bitcast.
-  V = peekThroughBitcast(V);
-  // Check that select is select ((cmp load V1, load V2), V1, V2) - minmax
-  // pattern.
-  CmpInst::Predicate Pred;
-  Instruction *L1;
-  Instruction *L2;
-  Value *LHS;
-  Value *RHS;
-  if (!match(V, m_Select(m_Cmp(Pred, m_Instruction(L1), m_Instruction(L2)),
-                         m_Value(LHS), m_Value(RHS))))
-    return false;
-  return (match(L1, m_Load(m_Specific(LHS))) &&
-          match(L2, m_Load(m_Specific(RHS)))) ||
-         (match(L1, m_Load(m_Specific(RHS))) &&
-          match(L2, m_Load(m_Specific(LHS))));
-}
-
-/// Combine loads to match the type of their uses' value after looking
-/// through intervening bitcasts.
-///
-/// The core idea here is that if the result of a load is used in an operation,
-/// we should load the type most conducive to that operation. For example, when
-/// loading an integer and converting that immediately to a pointer, we should
-/// instead directly load a pointer.
-///
-/// However, this routine must never change the width of a load or the number of
-/// loads as that would introduce a semantic change. This combine is expected to
-/// be a semantic no-op which just allows loads to more closely model the types
-/// of their consuming operations.
-///
-/// Currently, we also refuse to change the precise type used for an atomic load
-/// or a volatile load. This is debatable, and might be reasonable to change
-/// later. However, it is risky in case some backend or other part of LLVM is
-/// relying on the exact type loaded to select appropriate atomic operations.
-static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) {
-  // FIXME: We could probably with some care handle both volatile and ordered
-  // atomic loads here but it isn't clear that this is important.
-  if (!LI.isUnordered())
-    return nullptr;
-
-  if (LI.use_empty())
-    return nullptr;
-
-  // swifterror values can't be bitcasted.
-  if (LI.getPointerOperand()->isSwiftError())
-    return nullptr;
-
-  Type *Ty = LI.getType();
-  const DataLayout &DL = IC.getDataLayout();
-
-  // Try to canonicalize loads which are only ever stored to operate over
-  // integers instead of any other type. We only do this when the loaded type
-  // is sized and has a size exactly the same as its store size and the store
-  // size is a legal integer type.
-  // Do not perform canonicalization if minmax pattern is found (to avoid
-  // infinite loop).
-  if (!Ty->isIntegerTy() && Ty->isSized() &&
-      DL.isLegalInteger(DL.getTypeStoreSizeInBits(Ty)) &&
-      DL.getTypeStoreSizeInBits(Ty) == DL.getTypeSizeInBits(Ty) &&
-      !DL.isNonIntegralPointerType(Ty) &&
-      !isMinMaxWithLoads(
-          peekThroughBitcast(LI.getPointerOperand(), /*OneUseOnly=*/true))) {
-    if (all_of(LI.users(), [&LI](User *U) {
-          auto *SI = dyn_cast<StoreInst>(U);
-          return SI && SI->getPointerOperand() != &LI &&
-                 !SI->getPointerOperand()->isSwiftError();
-        })) {
-      LoadInst *NewLoad = combineLoadToNewType(
-          IC, LI,
-          Type::getIntNTy(LI.getContext(), DL.getTypeStoreSizeInBits(Ty)));
-      // Replace all the stores with stores of the newly loaded value.
-      for (auto UI = LI.user_begin(), UE = LI.user_end(); UI != UE;) {
-        auto *SI = cast<StoreInst>(*UI++);
-        IC.Builder.SetInsertPoint(SI);
-        combineStoreToNewValue(IC, *SI, NewLoad);
-        IC.eraseInstFromFunction(*SI);
-      }
-      assert(LI.use_empty() && "Failed to remove all users of the load!");
-      // Return the old load so the combiner can delete it safely.
-      return &LI;
-    }
-  }
-
-  // Fold away bit casts of the loaded value by loading the desired type.
-  // We can do this for BitCastInsts as well as casts from and to pointer types,
-  // as long as those are noops (i.e., the source or dest type have the same
-  // bitwidth as the target's pointers).
-  if (LI.hasOneUse())
-    if (auto* CI = dyn_cast<CastInst>(LI.user_back()))
-      if (CI->isNoopCast(DL))
-        if (!LI.isAtomic() || isSupportedAtomicType(CI->getDestTy())) {
-          LoadInst *NewLoad = combineLoadToNewType(IC, LI, CI->getDestTy());
-          CI->replaceAllUsesWith(NewLoad);
-          IC.eraseInstFromFunction(*CI);
-          return &LI;
-        }
-
-  // FIXME: We should also canonicalize loads of vectors when their elements are
-  // cast to other types.
-  return nullptr;
-}
-
-static Instruction *unpackLoadToAggregate(InstCombiner &IC, LoadInst &LI) {
-  // FIXME: We could probably with some care handle both volatile and atomic
-  // stores here but it isn't clear that this is important.
-  if (!LI.isSimple())
-    return nullptr;
-
-  Type *T = LI.getType();
-  if (!T->isAggregateType())
-    return nullptr;
-
-  StringRef Name = LI.getName();
-  assert(LI.getAlignment() && "Alignment must be set at this point");
-
-  if (auto *ST = dyn_cast<StructType>(T)) {
-    // If the struct only have one element, we unpack.
-    auto NumElements = ST->getNumElements();
-    if (NumElements == 1) {
-      LoadInst *NewLoad = combineLoadToNewType(IC, LI, ST->getTypeAtIndex(0U),
-                                               ".unpack");
-      AAMDNodes AAMD;
-      LI.getAAMetadata(AAMD);
-      NewLoad->setAAMetadata(AAMD);
-      return IC.replaceInstUsesWith(LI, IC.Builder.CreateInsertValue(
-        UndefValue::get(T), NewLoad, 0, Name));
-    }
-
-    // We don't want to break loads with padding here as we'd loose
-    // the knowledge that padding exists for the rest of the pipeline.
-    const DataLayout &DL = IC.getDataLayout();
-    auto *SL = DL.getStructLayout(ST);
-    if (SL->hasPadding())
-      return nullptr;
-
-    auto Align = LI.getAlignment();
-    if (!Align)
-      Align = DL.getABITypeAlignment(ST);
-
-    auto *Addr = LI.getPointerOperand();
-    auto *IdxType = Type::getInt32Ty(T->getContext());
-    auto *Zero = ConstantInt::get(IdxType, 0);
-
-    Value *V = UndefValue::get(T);
-    for (unsigned i = 0; i < NumElements; i++) {
-      Value *Indices[2] = {
-        Zero,
-        ConstantInt::get(IdxType, i),
-      };
-      auto *Ptr = IC.Builder.CreateInBoundsGEP(ST, Addr, makeArrayRef(Indices),
-                                               Name + ".elt");
-      auto EltAlign = MinAlign(Align, SL->getElementOffset(i));
-      auto *L = IC.Builder.CreateAlignedLoad(Ptr, EltAlign, Name + ".unpack");
-      // Propagate AA metadata. It'll still be valid on the narrowed load.
-      AAMDNodes AAMD;
-      LI.getAAMetadata(AAMD);
-      L->setAAMetadata(AAMD);
-      V = IC.Builder.CreateInsertValue(V, L, i);
-    }
-
-    V->setName(Name);
-    return IC.replaceInstUsesWith(LI, V);
-  }
-
-  if (auto *AT = dyn_cast<ArrayType>(T)) {
-    auto *ET = AT->getElementType();
-    auto NumElements = AT->getNumElements();
-    if (NumElements == 1) {
-      LoadInst *NewLoad = combineLoadToNewType(IC, LI, ET, ".unpack");
-      AAMDNodes AAMD;
-      LI.getAAMetadata(AAMD);
-      NewLoad->setAAMetadata(AAMD);
-      return IC.replaceInstUsesWith(LI, IC.Builder.CreateInsertValue(
-        UndefValue::get(T), NewLoad, 0, Name));
-    }
-
-    // Bail out if the array is too large. Ideally we would like to optimize
-    // arrays of arbitrary size but this has a terrible impact on compile time.
-    // The threshold here is chosen arbitrarily, maybe needs a little bit of
-    // tuning.
-    if (NumElements > IC.MaxArraySizeForCombine)
-      return nullptr;
-
-    const DataLayout &DL = IC.getDataLayout();
-    auto EltSize = DL.getTypeAllocSize(ET);
-    auto Align = LI.getAlignment();
-    if (!Align)
-      Align = DL.getABITypeAlignment(T);
-
-    auto *Addr = LI.getPointerOperand();
-    auto *IdxType = Type::getInt64Ty(T->getContext());
-    auto *Zero = ConstantInt::get(IdxType, 0);
-
-    Value *V = UndefValue::get(T);
-    uint64_t Offset = 0;
-    for (uint64_t i = 0; i < NumElements; i++) {
-      Value *Indices[2] = {
-        Zero,
-        ConstantInt::get(IdxType, i),
-      };
-      auto *Ptr = IC.Builder.CreateInBoundsGEP(AT, Addr, makeArrayRef(Indices),
-                                               Name + ".elt");
-      auto *L = IC.Builder.CreateAlignedLoad(Ptr, MinAlign(Align, Offset),
-                                             Name + ".unpack");
-      AAMDNodes AAMD;
-      LI.getAAMetadata(AAMD);
-      L->setAAMetadata(AAMD);
-      V = IC.Builder.CreateInsertValue(V, L, i);
-      Offset += EltSize;
-    }
-
-    V->setName(Name);
-    return IC.replaceInstUsesWith(LI, V);
-  }
-
-  return nullptr;
-}
-
-// If we can determine that all possible objects pointed to by the provided
-// pointer value are, not only dereferenceable, but also definitively less than
-// or equal to the provided maximum size, then return true. Otherwise, return
-// false (constant global values and allocas fall into this category).
-//
-// FIXME: This should probably live in ValueTracking (or similar).
-static bool isObjectSizeLessThanOrEq(Value *V, uint64_t MaxSize,
-                                     const DataLayout &DL) {
-  SmallPtrSet<Value *, 4> Visited;
-  SmallVector<Value *, 4> Worklist(1, V);
-
-  do {
-    Value *P = Worklist.pop_back_val();
-    P = P->stripPointerCasts();
-
-    if (!Visited.insert(P).second)
-      continue;
-
-    if (SelectInst *SI = dyn_cast<SelectInst>(P)) {
-      Worklist.push_back(SI->getTrueValue());
-      Worklist.push_back(SI->getFalseValue());
-      continue;
-    }
-
-    if (PHINode *PN = dyn_cast<PHINode>(P)) {
-      for (Value *IncValue : PN->incoming_values())
-        Worklist.push_back(IncValue);
-      continue;
-    }
-
-    if (GlobalAlias *GA = dyn_cast<GlobalAlias>(P)) {
-      if (GA->isInterposable())
-        return false;
-      Worklist.push_back(GA->getAliasee());
-      continue;
-    }
-
-    // If we know how big this object is, and it is less than MaxSize, continue
-    // searching. Otherwise, return false.
-    if (AllocaInst *AI = dyn_cast<AllocaInst>(P)) {
-      if (!AI->getAllocatedType()->isSized())
-        return false;
-
-      ConstantInt *CS = dyn_cast<ConstantInt>(AI->getArraySize());
-      if (!CS)
-        return false;
-
-      uint64_t TypeSize = DL.getTypeAllocSize(AI->getAllocatedType());
-      // Make sure that, even if the multiplication below would wrap as an
-      // uint64_t, we still do the right thing.
-      if ((CS->getValue().zextOrSelf(128)*APInt(128, TypeSize)).ugt(MaxSize))
-        return false;
-      continue;
-    }
-
-    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) {
-      if (!GV->hasDefinitiveInitializer() || !GV->isConstant())
-        return false;
-
-      uint64_t InitSize = DL.getTypeAllocSize(GV->getValueType());
-      if (InitSize > MaxSize)
-        return false;
-      continue;
-    }
-
-    return false;
-  } while (!Worklist.empty());
-
-  return true;
-}
-
-// If we're indexing into an object of a known size, and the outer index is
-// not a constant, but having any value but zero would lead to undefined
-// behavior, replace it with zero.
-//
-// For example, if we have:
-// @f.a = private unnamed_addr constant [1 x i32] [i32 12], align 4
-// ...
-// %arrayidx = getelementptr inbounds [1 x i32]* @f.a, i64 0, i64 %x
-// ... = load i32* %arrayidx, align 4
-// Then we know that we can replace %x in the GEP with i64 0.
-//
-// FIXME: We could fold any GEP index to zero that would cause UB if it were
-// not zero. Currently, we only handle the first such index. Also, we could
-// also search through non-zero constant indices if we kept track of the
-// offsets those indices implied.
-static bool canReplaceGEPIdxWithZero(InstCombiner &IC, GetElementPtrInst *GEPI,
-                                     Instruction *MemI, unsigned &Idx) {
-  if (GEPI->getNumOperands() < 2)
-    return false;
-
-  // Find the first non-zero index of a GEP. If all indices are zero, return
-  // one past the last index.
-  auto FirstNZIdx = [](const GetElementPtrInst *GEPI) {
-    unsigned I = 1;
-    for (unsigned IE = GEPI->getNumOperands(); I != IE; ++I) {
-      Value *V = GEPI->getOperand(I);
-      if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
-        if (CI->isZero())
-          continue;
-
-      break;
-    }
-
-    return I;
-  };
-
-  // Skip through initial 'zero' indices, and find the corresponding pointer
-  // type. See if the next index is not a constant.
-  Idx = FirstNZIdx(GEPI);
-  if (Idx == GEPI->getNumOperands())
-    return false;
-  if (isa<Constant>(GEPI->getOperand(Idx)))
-    return false;
-
-  SmallVector<Value *, 4> Ops(GEPI->idx_begin(), GEPI->idx_begin() + Idx);
-  Type *AllocTy =
-    GetElementPtrInst::getIndexedType(GEPI->getSourceElementType(), Ops);
-  if (!AllocTy || !AllocTy->isSized())
-    return false;
-  const DataLayout &DL = IC.getDataLayout();
-  uint64_t TyAllocSize = DL.getTypeAllocSize(AllocTy);
-
-  // If there are more indices after the one we might replace with a zero, make
-  // sure they're all non-negative. If any of them are negative, the overall
-  // address being computed might be before the base address determined by the
-  // first non-zero index.
-  auto IsAllNonNegative = [&]() {
-    for (unsigned i = Idx+1, e = GEPI->getNumOperands(); i != e; ++i) {
-      KnownBits Known = IC.computeKnownBits(GEPI->getOperand(i), 0, MemI);
-      if (Known.isNonNegative())
-        continue;
-      return false;
-    }
-
-    return true;
-  };
-
-  // FIXME: If the GEP is not inbounds, and there are extra indices after the
-  // one we'll replace, those could cause the address computation to wrap
-  // (rendering the IsAllNonNegative() check below insufficient). We can do
-  // better, ignoring zero indices (and other indices we can prove small
-  // enough not to wrap).
-  if (Idx+1 != GEPI->getNumOperands() && !GEPI->isInBounds())
-    return false;
-
-  // Note that isObjectSizeLessThanOrEq will return true only if the pointer is
-  // also known to be dereferenceable.
-  return isObjectSizeLessThanOrEq(GEPI->getOperand(0), TyAllocSize, DL) &&
-         IsAllNonNegative();
-}
-
-// If we're indexing into an object with a variable index for the memory
-// access, but the object has only one element, we can assume that the index
-// will always be zero. If we replace the GEP, return it.
-template <typename T>
-static Instruction *replaceGEPIdxWithZero(InstCombiner &IC, Value *Ptr,
-                                          T &MemI) {
-  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Ptr)) {
-    unsigned Idx;
-    if (canReplaceGEPIdxWithZero(IC, GEPI, &MemI, Idx)) {
-      Instruction *NewGEPI = GEPI->clone();
-      NewGEPI->setOperand(Idx,
-        ConstantInt::get(GEPI->getOperand(Idx)->getType(), 0));
-      NewGEPI->insertBefore(GEPI);
-      MemI.setOperand(MemI.getPointerOperandIndex(), NewGEPI);
-      return NewGEPI;
-    }
-  }
-
-  return nullptr;
-}
-
-static bool canSimplifyNullStoreOrGEP(StoreInst &SI) {
-  if (NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace()))
-    return false;
-
-  auto *Ptr = SI.getPointerOperand();
-  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Ptr))
-    Ptr = GEPI->getOperand(0);
-  return (isa<ConstantPointerNull>(Ptr) &&
-          !NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace()));
-}
-
-static bool canSimplifyNullLoadOrGEP(LoadInst &LI, Value *Op) {
-  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
-    const Value *GEPI0 = GEPI->getOperand(0);
-    if (isa<ConstantPointerNull>(GEPI0) &&
-        !NullPointerIsDefined(LI.getFunction(), GEPI->getPointerAddressSpace()))
-      return true;
-  }
-  if (isa<UndefValue>(Op) ||
-      (isa<ConstantPointerNull>(Op) &&
-       !NullPointerIsDefined(LI.getFunction(), LI.getPointerAddressSpace())))
-    return true;
-  return false;
-}
-
-Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
-  Value *Op = LI.getOperand(0);
-
-  // Try to canonicalize the loaded type.
-  if (Instruction *Res = combineLoadToOperationType(*this, LI))
-    return Res;
-
-  // Attempt to improve the alignment.
-  unsigned KnownAlign = getOrEnforceKnownAlignment(
-      Op, DL.getPrefTypeAlignment(LI.getType()), DL, &LI, &AC, &DT);
-  unsigned LoadAlign = LI.getAlignment();
-  unsigned EffectiveLoadAlign =
-      LoadAlign != 0 ? LoadAlign : DL.getABITypeAlignment(LI.getType());
-
-  if (KnownAlign > EffectiveLoadAlign)
-    LI.setAlignment(KnownAlign);
-  else if (LoadAlign == 0)
-    LI.setAlignment(EffectiveLoadAlign);
-
-  // Replace GEP indices if possible.
-  if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Op, LI)) {
-      Worklist.Add(NewGEPI);
-      return &LI;
-  }
-
-  if (Instruction *Res = unpackLoadToAggregate(*this, LI))
-    return Res;
-
-  // Do really simple store-to-load forwarding and load CSE, to catch cases
-  // where there are several consecutive memory accesses to the same location,
-  // separated by a few arithmetic operations.
-  BasicBlock::iterator BBI(LI);
-  bool IsLoadCSE = false;
-  if (Value *AvailableVal = FindAvailableLoadedValue(
-          &LI, LI.getParent(), BBI, DefMaxInstsToScan, AA, &IsLoadCSE)) {
-    if (IsLoadCSE)
-      combineMetadataForCSE(cast<LoadInst>(AvailableVal), &LI, false);
-
-    return replaceInstUsesWith(
-        LI, Builder.CreateBitOrPointerCast(AvailableVal, LI.getType(),
-                                           LI.getName() + ".cast"));
-  }
-
-  // None of the following transforms are legal for volatile/ordered atomic
-  // loads.  Most of them do apply for unordered atomics.
-  if (!LI.isUnordered()) return nullptr;
-
-  // load(gep null, ...) -> unreachable
-  // load null/undef -> unreachable
-  // TODO: Consider a target hook for valid address spaces for this xforms.
-  if (canSimplifyNullLoadOrGEP(LI, Op)) {
-    // Insert a new store to null instruction before the load to indicate
-    // that this code is not reachable.  We do this instead of inserting
-    // an unreachable instruction directly because we cannot modify the
-    // CFG.
-    StoreInst *SI = new StoreInst(UndefValue::get(LI.getType()),
-                                  Constant::getNullValue(Op->getType()), &LI);
-    SI->setDebugLoc(LI.getDebugLoc());
-    return replaceInstUsesWith(LI, UndefValue::get(LI.getType()));
-  }
-
-  if (Op->hasOneUse()) {
-    // Change select and PHI nodes to select values instead of addresses: this
-    // helps alias analysis out a lot, allows many others simplifications, and
-    // exposes redundancy in the code.
-    //
-    // Note that we cannot do the transformation unless we know that the
-    // introduced loads cannot trap!  Something like this is valid as long as
-    // the condition is always false: load (select bool %C, int* null, int* %G),
-    // but it would not be valid if we transformed it to load from null
-    // unconditionally.
-    //
-    if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
-      // load (select (Cond, &V1, &V2))  --> select(Cond, load &V1, load &V2).
-      unsigned Align = LI.getAlignment();
-      if (isSafeToLoadUnconditionally(SI->getOperand(1), Align, DL, SI) &&
-          isSafeToLoadUnconditionally(SI->getOperand(2), Align, DL, SI)) {
-        LoadInst *V1 = Builder.CreateLoad(SI->getOperand(1),
-                                          SI->getOperand(1)->getName()+".val");
-        LoadInst *V2 = Builder.CreateLoad(SI->getOperand(2),
-                                          SI->getOperand(2)->getName()+".val");
-        assert(LI.isUnordered() && "implied by above");
-        V1->setAlignment(Align);
-        V1->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
-        V2->setAlignment(Align);
-        V2->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
-        return SelectInst::Create(SI->getCondition(), V1, V2);
-      }
-
-      // load (select (cond, null, P)) -> load P
-      if (isa<ConstantPointerNull>(SI->getOperand(1)) &&
-          !NullPointerIsDefined(SI->getFunction(),
-                                LI.getPointerAddressSpace())) {
-        LI.setOperand(0, SI->getOperand(2));
-        return &LI;
-      }
-
-      // load (select (cond, P, null)) -> load P
-      if (isa<ConstantPointerNull>(SI->getOperand(2)) &&
-          !NullPointerIsDefined(SI->getFunction(),
-                                LI.getPointerAddressSpace())) {
-        LI.setOperand(0, SI->getOperand(1));
-        return &LI;
-      }
-    }
-  }
-  return nullptr;
-}
-
-/// Look for extractelement/insertvalue sequence that acts like a bitcast.
-///
-/// \returns underlying value that was "cast", or nullptr otherwise.
-///
-/// For example, if we have:
-///
-///     %E0 = extractelement <2 x double> %U, i32 0
-///     %V0 = insertvalue [2 x double] undef, double %E0, 0
-///     %E1 = extractelement <2 x double> %U, i32 1
-///     %V1 = insertvalue [2 x double] %V0, double %E1, 1
-///
-/// and the layout of a <2 x double> is isomorphic to a [2 x double],
-/// then %V1 can be safely approximated by a conceptual "bitcast" of %U.
-/// Note that %U may contain non-undef values where %V1 has undef.
-static Value *likeBitCastFromVector(InstCombiner &IC, Value *V) {
-  Value *U = nullptr;
-  while (auto *IV = dyn_cast<InsertValueInst>(V)) {
-    auto *E = dyn_cast<ExtractElementInst>(IV->getInsertedValueOperand());
-    if (!E)
-      return nullptr;
-    auto *W = E->getVectorOperand();
-    if (!U)
-      U = W;
-    else if (U != W)
-      return nullptr;
-    auto *CI = dyn_cast<ConstantInt>(E->getIndexOperand());
-    if (!CI || IV->getNumIndices() != 1 || CI->getZExtValue() != *IV->idx_begin())
-      return nullptr;
-    V = IV->getAggregateOperand();
-  }
-  if (!isa<UndefValue>(V) ||!U)
-    return nullptr;
-
-  auto *UT = cast<VectorType>(U->getType());
-  auto *VT = V->getType();
-  // Check that types UT and VT are bitwise isomorphic.
-  const auto &DL = IC.getDataLayout();
-  if (DL.getTypeStoreSizeInBits(UT) != DL.getTypeStoreSizeInBits(VT)) {
-    return nullptr;
-  }
-  if (auto *AT = dyn_cast<ArrayType>(VT)) {
-    if (AT->getNumElements() != UT->getNumElements())
-      return nullptr;
-  } else {
-    auto *ST = cast<StructType>(VT);
-    if (ST->getNumElements() != UT->getNumElements())
-      return nullptr;
-    for (const auto *EltT : ST->elements()) {
-      if (EltT != UT->getElementType())
-        return nullptr;
-    }
-  }
-  return U;
-}
-
-/// Combine stores to match the type of value being stored.
-///
-/// The core idea here is that the memory does not have any intrinsic type and
-/// where we can we should match the type of a store to the type of value being
-/// stored.
-///
-/// However, this routine must never change the width of a store or the number of
-/// stores as that would introduce a semantic change. This combine is expected to
-/// be a semantic no-op which just allows stores to more closely model the types
-/// of their incoming values.
-///
-/// Currently, we also refuse to change the precise type used for an atomic or
-/// volatile store. This is debatable, and might be reasonable to change later.
-/// However, it is risky in case some backend or other part of LLVM is relying
-/// on the exact type stored to select appropriate atomic operations.
-///
-/// \returns true if the store was successfully combined away. This indicates
-/// the caller must erase the store instruction. We have to let the caller erase
-/// the store instruction as otherwise there is no way to signal whether it was
-/// combined or not: IC.EraseInstFromFunction returns a null pointer.
-static bool combineStoreToValueType(InstCombiner &IC, StoreInst &SI) {
-  // FIXME: We could probably with some care handle both volatile and ordered
-  // atomic stores here but it isn't clear that this is important.
-  if (!SI.isUnordered())
-    return false;
-
-  // swifterror values can't be bitcasted.
-  if (SI.getPointerOperand()->isSwiftError())
-    return false;
-
-  Value *V = SI.getValueOperand();
-
-  // Fold away bit casts of the stored value by storing the original type.
-  if (auto *BC = dyn_cast<BitCastInst>(V)) {
-    V = BC->getOperand(0);
-    if (!SI.isAtomic() || isSupportedAtomicType(V->getType())) {
-      combineStoreToNewValue(IC, SI, V);
-      return true;
-    }
-  }
-
-  if (Value *U = likeBitCastFromVector(IC, V))
-    if (!SI.isAtomic() || isSupportedAtomicType(U->getType())) {
-      combineStoreToNewValue(IC, SI, U);
-      return true;
-    }
-
-  // FIXME: We should also canonicalize stores of vectors when their elements
-  // are cast to other types.
-  return false;
-}
-
-static bool unpackStoreToAggregate(InstCombiner &IC, StoreInst &SI) {
-  // FIXME: We could probably with some care handle both volatile and atomic
-  // stores here but it isn't clear that this is important.
-  if (!SI.isSimple())
-    return false;
-
-  Value *V = SI.getValueOperand();
-  Type *T = V->getType();
-
-  if (!T->isAggregateType())
-    return false;
-
-  if (auto *ST = dyn_cast<StructType>(T)) {
-    // If the struct only have one element, we unpack.
-    unsigned Count = ST->getNumElements();
-    if (Count == 1) {
-      V = IC.Builder.CreateExtractValue(V, 0);
-      combineStoreToNewValue(IC, SI, V);
-      return true;
-    }
-
-    // We don't want to break loads with padding here as we'd loose
-    // the knowledge that padding exists for the rest of the pipeline.
-    const DataLayout &DL = IC.getDataLayout();
-    auto *SL = DL.getStructLayout(ST);
-    if (SL->hasPadding())
-      return false;
-
-    auto Align = SI.getAlignment();
-    if (!Align)
-      Align = DL.getABITypeAlignment(ST);
-
-    SmallString<16> EltName = V->getName();
-    EltName += ".elt";
-    auto *Addr = SI.getPointerOperand();
-    SmallString<16> AddrName = Addr->getName();
-    AddrName += ".repack";
-
-    auto *IdxType = Type::getInt32Ty(ST->getContext());
-    auto *Zero = ConstantInt::get(IdxType, 0);
-    for (unsigned i = 0; i < Count; i++) {
-      Value *Indices[2] = {
-        Zero,
-        ConstantInt::get(IdxType, i),
-      };
-      auto *Ptr = IC.Builder.CreateInBoundsGEP(ST, Addr, makeArrayRef(Indices),
-                                               AddrName);
-      auto *Val = IC.Builder.CreateExtractValue(V, i, EltName);
-      auto EltAlign = MinAlign(Align, SL->getElementOffset(i));
-      llvm::Instruction *NS = IC.Builder.CreateAlignedStore(Val, Ptr, EltAlign);
-      AAMDNodes AAMD;
-      SI.getAAMetadata(AAMD);
-      NS->setAAMetadata(AAMD);
-    }
-
-    return true;
-  }
-
-  if (auto *AT = dyn_cast<ArrayType>(T)) {
-    // If the array only have one element, we unpack.
-    auto NumElements = AT->getNumElements();
-    if (NumElements == 1) {
-      V = IC.Builder.CreateExtractValue(V, 0);
-      combineStoreToNewValue(IC, SI, V);
-      return true;
-    }
-
-    // Bail out if the array is too large. Ideally we would like to optimize
-    // arrays of arbitrary size but this has a terrible impact on compile time.
-    // The threshold here is chosen arbitrarily, maybe needs a little bit of
-    // tuning.
-    if (NumElements > IC.MaxArraySizeForCombine)
-      return false;
-
-    const DataLayout &DL = IC.getDataLayout();
-    auto EltSize = DL.getTypeAllocSize(AT->getElementType());
-    auto Align = SI.getAlignment();
-    if (!Align)
-      Align = DL.getABITypeAlignment(T);
-
-    SmallString<16> EltName = V->getName();
-    EltName += ".elt";
-    auto *Addr = SI.getPointerOperand();
-    SmallString<16> AddrName = Addr->getName();
-    AddrName += ".repack";
-
-    auto *IdxType = Type::getInt64Ty(T->getContext());
-    auto *Zero = ConstantInt::get(IdxType, 0);
-
-    uint64_t Offset = 0;
-    for (uint64_t i = 0; i < NumElements; i++) {
-      Value *Indices[2] = {
-        Zero,
-        ConstantInt::get(IdxType, i),
-      };
-      auto *Ptr = IC.Builder.CreateInBoundsGEP(AT, Addr, makeArrayRef(Indices),
-                                               AddrName);
-      auto *Val = IC.Builder.CreateExtractValue(V, i, EltName);
-      auto EltAlign = MinAlign(Align, Offset);
-      Instruction *NS = IC.Builder.CreateAlignedStore(Val, Ptr, EltAlign);
-      AAMDNodes AAMD;
-      SI.getAAMetadata(AAMD);
-      NS->setAAMetadata(AAMD);
-      Offset += EltSize;
-    }
-
-    return true;
-  }
-
-  return false;
-}
-
-/// equivalentAddressValues - Test if A and B will obviously have the same
-/// value. This includes recognizing that %t0 and %t1 will have the same
-/// value in code like this:
-///   %t0 = getelementptr \@a, 0, 3
-///   store i32 0, i32* %t0
-///   %t1 = getelementptr \@a, 0, 3
-///   %t2 = load i32* %t1
-///
-static bool equivalentAddressValues(Value *A, Value *B) {
-  // Test if the values are trivially equivalent.
-  if (A == B) return true;
-
-  // Test if the values come form identical arithmetic instructions.
-  // This uses isIdenticalToWhenDefined instead of isIdenticalTo because
-  // its only used to compare two uses within the same basic block, which
-  // means that they'll always either have the same value or one of them
-  // will have an undefined value.
-  if (isa<BinaryOperator>(A) ||
-      isa<CastInst>(A) ||
-      isa<PHINode>(A) ||
-      isa<GetElementPtrInst>(A))
-    if (Instruction *BI = dyn_cast<Instruction>(B))
-      if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
-        return true;
-
-  // Otherwise they may not be equivalent.
-  return false;
-}
-
-/// Converts store (bitcast (load (bitcast (select ...)))) to
-/// store (load (select ...)), where select is minmax:
-/// select ((cmp load V1, load V2), V1, V2).
-static bool removeBitcastsFromLoadStoreOnMinMax(InstCombiner &IC,
-                                                StoreInst &SI) {
-  // bitcast?
-  if (!match(SI.getPointerOperand(), m_BitCast(m_Value())))
-    return false;
-  // load? integer?
-  Value *LoadAddr;
-  if (!match(SI.getValueOperand(), m_Load(m_BitCast(m_Value(LoadAddr)))))
-    return false;
-  auto *LI = cast<LoadInst>(SI.getValueOperand());
-  if (!LI->getType()->isIntegerTy())
-    return false;
-  if (!isMinMaxWithLoads(LoadAddr))
-    return false;
-
-  if (!all_of(LI->users(), [LI, LoadAddr](User *U) {
-        auto *SI = dyn_cast<StoreInst>(U);
-        return SI && SI->getPointerOperand() != LI &&
-               peekThroughBitcast(SI->getPointerOperand()) != LoadAddr &&
-               !SI->getPointerOperand()->isSwiftError();
-      }))
-    return false;
-
-  IC.Builder.SetInsertPoint(LI);
-  LoadInst *NewLI = combineLoadToNewType(
-      IC, *LI, LoadAddr->getType()->getPointerElementType());
-  // Replace all the stores with stores of the newly loaded value.
-  for (auto *UI : LI->users()) {
-    auto *USI = cast<StoreInst>(UI);
-    IC.Builder.SetInsertPoint(USI);
-    combineStoreToNewValue(IC, *USI, NewLI);
-  }
-  IC.replaceInstUsesWith(*LI, UndefValue::get(LI->getType()));
-  IC.eraseInstFromFunction(*LI);
-  return true;
-}
-
-Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
-  Value *Val = SI.getOperand(0);
-  Value *Ptr = SI.getOperand(1);
-
-  // Try to canonicalize the stored type.
-  if (combineStoreToValueType(*this, SI))
-    return eraseInstFromFunction(SI);
-
-  // Attempt to improve the alignment.
-  unsigned KnownAlign = getOrEnforceKnownAlignment(
-      Ptr, DL.getPrefTypeAlignment(Val->getType()), DL, &SI, &AC, &DT);
-  unsigned StoreAlign = SI.getAlignment();
-  unsigned EffectiveStoreAlign =
-      StoreAlign != 0 ? StoreAlign : DL.getABITypeAlignment(Val->getType());
-
-  if (KnownAlign > EffectiveStoreAlign)
-    SI.setAlignment(KnownAlign);
-  else if (StoreAlign == 0)
-    SI.setAlignment(EffectiveStoreAlign);
-
-  // Try to canonicalize the stored type.
-  if (unpackStoreToAggregate(*this, SI))
-    return eraseInstFromFunction(SI);
-
-  if (removeBitcastsFromLoadStoreOnMinMax(*this, SI))
-    return eraseInstFromFunction(SI);
-
-  // Replace GEP indices if possible.
-  if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Ptr, SI)) {
-      Worklist.Add(NewGEPI);
-      return &SI;
-  }
-
-  // Don't hack volatile/ordered stores.
-  // FIXME: Some bits are legal for ordered atomic stores; needs refactoring.
-  if (!SI.isUnordered()) return nullptr;
-
-  // If the RHS is an alloca with a single use, zapify the store, making the
-  // alloca dead.
-  if (Ptr->hasOneUse()) {
-    if (isa<AllocaInst>(Ptr))
-      return eraseInstFromFunction(SI);
-    if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
-      if (isa<AllocaInst>(GEP->getOperand(0))) {
-        if (GEP->getOperand(0)->hasOneUse())
-          return eraseInstFromFunction(SI);
-      }
-    }
-  }
-
-  // Do really simple DSE, to catch cases where there are several consecutive
-  // stores to the same location, separated by a few arithmetic operations. This
-  // situation often occurs with bitfield accesses.
-  BasicBlock::iterator BBI(SI);
-  for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
-       --ScanInsts) {
-    --BBI;
-    // Don't count debug info directives, lest they affect codegen,
-    // and we skip pointer-to-pointer bitcasts, which are NOPs.
-    if (isa<DbgInfoIntrinsic>(BBI) ||
-        (isa<BitCastInst>(BBI) && BBI->getType()->isPointerTy())) {
-      ScanInsts++;
-      continue;
-    }
-
-    if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
-      // Prev store isn't volatile, and stores to the same location?
-      if (PrevSI->isUnordered() && equivalentAddressValues(PrevSI->getOperand(1),
-                                                        SI.getOperand(1))) {
-        ++NumDeadStore;
-        ++BBI;
-        eraseInstFromFunction(*PrevSI);
-        continue;
-      }
-      break;
-    }
-
-    // If this is a load, we have to stop.  However, if the loaded value is from
-    // the pointer we're loading and is producing the pointer we're storing,
-    // then *this* store is dead (X = load P; store X -> P).
-    if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
-      if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr)) {
-        assert(SI.isUnordered() && "can't eliminate ordering operation");
-        return eraseInstFromFunction(SI);
-      }
-
-      // Otherwise, this is a load from some other location.  Stores before it
-      // may not be dead.
-      break;
-    }
-
-    // Don't skip over loads, throws or things that can modify memory.
-    if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory() || BBI->mayThrow())
-      break;
-  }
-
-  // store X, null    -> turns into 'unreachable' in SimplifyCFG
-  // store X, GEP(null, Y) -> turns into 'unreachable' in SimplifyCFG
-  if (canSimplifyNullStoreOrGEP(SI)) {
-    if (!isa<UndefValue>(Val)) {
-      SI.setOperand(0, UndefValue::get(Val->getType()));
-      if (Instruction *U = dyn_cast<Instruction>(Val))
-        Worklist.Add(U);  // Dropped a use.
-    }
-    return nullptr;  // Do not modify these!
-  }
-
-  // store undef, Ptr -> noop
-  if (isa<UndefValue>(Val))
-    return eraseInstFromFunction(SI);
-
-  // If this store is the second-to-last instruction in the basic block
-  // (excluding debug info and bitcasts of pointers) and if the block ends with
-  // an unconditional branch, try to move the store to the successor block.
-  BBI = SI.getIterator();
-  do {
-    ++BBI;
-  } while (isa<DbgInfoIntrinsic>(BBI) ||
-           (isa<BitCastInst>(BBI) && BBI->getType()->isPointerTy()));
-
-  if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
-    if (BI->isUnconditional())
-      mergeStoreIntoSuccessor(SI);
-
-  return nullptr;
-}
-
-/// Try to transform:
-///   if () { *P = v1; } else { *P = v2 }
-/// or:
-///   *P = v1; if () { *P = v2; }
-/// into a phi node with a store in the successor.
-bool InstCombiner::mergeStoreIntoSuccessor(StoreInst &SI) {
-  assert(SI.isUnordered() &&
-         "This code has not been audited for volatile or ordered store case.");
-
-  // Check if the successor block has exactly 2 incoming edges.
-  BasicBlock *StoreBB = SI.getParent();
-  BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
-  if (!DestBB->hasNPredecessors(2))
-    return false;
-
-  // Capture the other block (the block that doesn't contain our store).
-  pred_iterator PredIter = pred_begin(DestBB);
-  if (*PredIter == StoreBB)
-    ++PredIter;
-  BasicBlock *OtherBB = *PredIter;
-
-  // Bail out if all of the relevant blocks aren't distinct. This can happen,
-  // for example, if SI is in an infinite loop.
-  if (StoreBB == DestBB || OtherBB == DestBB)
-    return false;
-
-  // Verify that the other block ends in a branch and is not otherwise empty.
-  BasicBlock::iterator BBI(OtherBB->getTerminator());
-  BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
-  if (!OtherBr || BBI == OtherBB->begin())
-    return false;
-
-  // If the other block ends in an unconditional branch, check for the 'if then
-  // else' case. There is an instruction before the branch.
-  StoreInst *OtherStore = nullptr;
-  if (OtherBr->isUnconditional()) {
-    --BBI;
-    // Skip over debugging info.
-    while (isa<DbgInfoIntrinsic>(BBI) ||
-           (isa<BitCastInst>(BBI) && BBI->getType()->isPointerTy())) {
-      if (BBI==OtherBB->begin())
-        return false;
-      --BBI;
-    }
-    // If this isn't a store, isn't a store to the same location, or is not the
-    // right kind of store, bail out.
-    OtherStore = dyn_cast<StoreInst>(BBI);
-    if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
-        !SI.isSameOperationAs(OtherStore))
-      return false;
-  } else {
-    // Otherwise, the other block ended with a conditional branch. If one of the
-    // destinations is StoreBB, then we have the if/then case.
-    if (OtherBr->getSuccessor(0) != StoreBB &&
-        OtherBr->getSuccessor(1) != StoreBB)
-      return false;
-
-    // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
-    // if/then triangle. See if there is a store to the same ptr as SI that
-    // lives in OtherBB.
-    for (;; --BBI) {
-      // Check to see if we find the matching store.
-      if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
-        if (OtherStore->getOperand(1) != SI.getOperand(1) ||
-            !SI.isSameOperationAs(OtherStore))
-          return false;
-        break;
-      }
-      // If we find something that may be using or overwriting the stored
-      // value, or if we run out of instructions, we can't do the transform.
-      if (BBI->mayReadFromMemory() || BBI->mayThrow() ||
-          BBI->mayWriteToMemory() || BBI == OtherBB->begin())
-        return false;
-    }
-
-    // In order to eliminate the store in OtherBr, we have to make sure nothing
-    // reads or overwrites the stored value in StoreBB.
-    for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
-      // FIXME: This should really be AA driven.
-      if (I->mayReadFromMemory() || I->mayThrow() || I->mayWriteToMemory())
-        return false;
-    }
-  }
-
-  // Insert a PHI node now if we need it.
-  Value *MergedVal = OtherStore->getOperand(0);
-  // The debug locations of the original instructions might differ. Merge them.
-  DebugLoc MergedLoc = DILocation::getMergedLocation(SI.getDebugLoc(),
-                                                     OtherStore->getDebugLoc());
-  if (MergedVal != SI.getOperand(0)) {
-    PHINode *PN = PHINode::Create(MergedVal->getType(), 2, "storemerge");
-    PN->addIncoming(SI.getOperand(0), SI.getParent());
-    PN->addIncoming(OtherStore->getOperand(0), OtherBB);
-    MergedVal = InsertNewInstBefore(PN, DestBB->front());
-    PN->setDebugLoc(MergedLoc);
-  }
-
-  // Advance to a place where it is safe to insert the new store and insert it.
-  BBI = DestBB->getFirstInsertionPt();
-  StoreInst *NewSI = new StoreInst(MergedVal, SI.getOperand(1),
-                                   SI.isVolatile(), SI.getAlignment(),
-                                   SI.getOrdering(), SI.getSyncScopeID());
-  InsertNewInstBefore(NewSI, *BBI);
-  NewSI->setDebugLoc(MergedLoc);
-
-  // If the two stores had AA tags, merge them.
-  AAMDNodes AATags;
-  SI.getAAMetadata(AATags);
-  if (AATags) {
-    OtherStore->getAAMetadata(AATags, /* Merge = */ true);
-    NewSI->setAAMetadata(AATags);
-  }
-
-  // Nuke the old stores.
-  eraseInstFromFunction(SI);
-  eraseInstFromFunction(*OtherStore);
-  return true;
-}