Remove LLVM 8.0.1 files.

1 files changed, 0 insertions, 1261 deletions

diff --git a/gnu/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp b/gnu/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
deleted file mode 100644
index 7603cf4d795..00000000000
--- a/gnu/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ /dev/null
@@ -1,1261 +0,0 @@
-//===- InstCombinePHI.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 visitPHINode function.
-//
-//===----------------------------------------------------------------------===//
-
-#include "InstCombineInternal.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/InstructionSimplify.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/IR/PatternMatch.h"
-using namespace llvm;
-using namespace llvm::PatternMatch;
-
-#define DEBUG_TYPE "instcombine"
-
-static cl::opt<unsigned>
-MaxNumPhis("instcombine-max-num-phis", cl::init(512),
-           cl::desc("Maximum number phis to handle in intptr/ptrint folding"));
-
-/// The PHI arguments will be folded into a single operation with a PHI node
-/// as input. The debug location of the single operation will be the merged
-/// locations of the original PHI node arguments.
-void InstCombiner::PHIArgMergedDebugLoc(Instruction *Inst, PHINode &PN) {
-  auto *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
-  Inst->setDebugLoc(FirstInst->getDebugLoc());
-  // We do not expect a CallInst here, otherwise, N-way merging of DebugLoc
-  // will be inefficient.
-  assert(!isa<CallInst>(Inst));
-
-  for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
-    auto *I = cast<Instruction>(PN.getIncomingValue(i));
-    Inst->applyMergedLocation(Inst->getDebugLoc(), I->getDebugLoc());
-  }
-}
-
-// Replace Integer typed PHI PN if the PHI's value is used as a pointer value.
-// If there is an existing pointer typed PHI that produces the same value as PN,
-// replace PN and the IntToPtr operation with it. Otherwise, synthesize a new
-// PHI node:
-//
-// Case-1:
-// bb1:
-//     int_init = PtrToInt(ptr_init)
-//     br label %bb2
-// bb2:
-//    int_val = PHI([int_init, %bb1], [int_val_inc, %bb2]
-//    ptr_val = PHI([ptr_init, %bb1], [ptr_val_inc, %bb2]
-//    ptr_val2 = IntToPtr(int_val)
-//    ...
-//    use(ptr_val2)
-//    ptr_val_inc = ...
-//    inc_val_inc = PtrToInt(ptr_val_inc)
-//
-// ==>
-// bb1:
-//     br label %bb2
-// bb2:
-//    ptr_val = PHI([ptr_init, %bb1], [ptr_val_inc, %bb2]
-//    ...
-//    use(ptr_val)
-//    ptr_val_inc = ...
-//
-// Case-2:
-// bb1:
-//    int_ptr = BitCast(ptr_ptr)
-//    int_init = Load(int_ptr)
-//    br label %bb2
-// bb2:
-//    int_val = PHI([int_init, %bb1], [int_val_inc, %bb2]
-//    ptr_val2 = IntToPtr(int_val)
-//    ...
-//    use(ptr_val2)
-//    ptr_val_inc = ...
-//    inc_val_inc = PtrToInt(ptr_val_inc)
-// ==>
-// bb1:
-//    ptr_init = Load(ptr_ptr)
-//    br label %bb2
-// bb2:
-//    ptr_val = PHI([ptr_init, %bb1], [ptr_val_inc, %bb2]
-//    ...
-//    use(ptr_val)
-//    ptr_val_inc = ...
-//    ...
-//
-Instruction *InstCombiner::FoldIntegerTypedPHI(PHINode &PN) {
-  if (!PN.getType()->isIntegerTy())
-    return nullptr;
-  if (!PN.hasOneUse())
-    return nullptr;
-
-  auto *IntToPtr = dyn_cast<IntToPtrInst>(PN.user_back());
-  if (!IntToPtr)
-    return nullptr;
-
-  // Check if the pointer is actually used as pointer:
-  auto HasPointerUse = [](Instruction *IIP) {
-    for (User *U : IIP->users()) {
-      Value *Ptr = nullptr;
-      if (LoadInst *LoadI = dyn_cast<LoadInst>(U)) {
-        Ptr = LoadI->getPointerOperand();
-      } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
-        Ptr = SI->getPointerOperand();
-      } else if (GetElementPtrInst *GI = dyn_cast<GetElementPtrInst>(U)) {
-        Ptr = GI->getPointerOperand();
-      }
-
-      if (Ptr && Ptr == IIP)
-        return true;
-    }
-    return false;
-  };
-
-  if (!HasPointerUse(IntToPtr))
-    return nullptr;
-
-  if (DL.getPointerSizeInBits(IntToPtr->getAddressSpace()) !=
-      DL.getTypeSizeInBits(IntToPtr->getOperand(0)->getType()))
-    return nullptr;
-
-  SmallVector<Value *, 4> AvailablePtrVals;
-  for (unsigned i = 0; i != PN.getNumIncomingValues(); ++i) {
-    Value *Arg = PN.getIncomingValue(i);
-
-    // First look backward:
-    if (auto *PI = dyn_cast<PtrToIntInst>(Arg)) {
-      AvailablePtrVals.emplace_back(PI->getOperand(0));
-      continue;
-    }
-
-    // Next look forward:
-    Value *ArgIntToPtr = nullptr;
-    for (User *U : Arg->users()) {
-      if (isa<IntToPtrInst>(U) && U->getType() == IntToPtr->getType() &&
-          (DT.dominates(cast<Instruction>(U), PN.getIncomingBlock(i)) ||
-           cast<Instruction>(U)->getParent() == PN.getIncomingBlock(i))) {
-        ArgIntToPtr = U;
-        break;
-      }
-    }
-
-    if (ArgIntToPtr) {
-      AvailablePtrVals.emplace_back(ArgIntToPtr);
-      continue;
-    }
-
-    // If Arg is defined by a PHI, allow it. This will also create
-    // more opportunities iteratively.
-    if (isa<PHINode>(Arg)) {
-      AvailablePtrVals.emplace_back(Arg);
-      continue;
-    }
-
-    // For a single use integer load:
-    auto *LoadI = dyn_cast<LoadInst>(Arg);
-    if (!LoadI)
-      return nullptr;
-
-    if (!LoadI->hasOneUse())
-      return nullptr;
-
-    // Push the integer typed Load instruction into the available
-    // value set, and fix it up later when the pointer typed PHI
-    // is synthesized.
-    AvailablePtrVals.emplace_back(LoadI);
-  }
-
-  // Now search for a matching PHI
-  auto *BB = PN.getParent();
-  assert(AvailablePtrVals.size() == PN.getNumIncomingValues() &&
-         "Not enough available ptr typed incoming values");
-  PHINode *MatchingPtrPHI = nullptr;
-  unsigned NumPhis = 0;
-  for (auto II = BB->begin(), EI = BasicBlock::iterator(BB->getFirstNonPHI());
-       II != EI; II++, NumPhis++) {
-    // FIXME: consider handling this in AggressiveInstCombine
-    if (NumPhis > MaxNumPhis)
-      return nullptr;
-    PHINode *PtrPHI = dyn_cast<PHINode>(II);
-    if (!PtrPHI || PtrPHI == &PN || PtrPHI->getType() != IntToPtr->getType())
-      continue;
-    MatchingPtrPHI = PtrPHI;
-    for (unsigned i = 0; i != PtrPHI->getNumIncomingValues(); ++i) {
-      if (AvailablePtrVals[i] !=
-          PtrPHI->getIncomingValueForBlock(PN.getIncomingBlock(i))) {
-        MatchingPtrPHI = nullptr;
-        break;
-      }
-    }
-
-    if (MatchingPtrPHI)
-      break;
-  }
-
-  if (MatchingPtrPHI) {
-    assert(MatchingPtrPHI->getType() == IntToPtr->getType() &&
-           "Phi's Type does not match with IntToPtr");
-    // The PtrToCast + IntToPtr will be simplified later
-    return CastInst::CreateBitOrPointerCast(MatchingPtrPHI,
-                                            IntToPtr->getOperand(0)->getType());
-  }
-
-  // If it requires a conversion for every PHI operand, do not do it.
-  if (all_of(AvailablePtrVals, [&](Value *V) {
-        return (V->getType() != IntToPtr->getType()) || isa<IntToPtrInst>(V);
-      }))
-    return nullptr;
-
-  // If any of the operand that requires casting is a terminator
-  // instruction, do not do it.
-  if (any_of(AvailablePtrVals, [&](Value *V) {
-        if (V->getType() == IntToPtr->getType())
-          return false;
-
-        auto *Inst = dyn_cast<Instruction>(V);
-        return Inst && Inst->isTerminator();
-      }))
-    return nullptr;
-
-  PHINode *NewPtrPHI = PHINode::Create(
-      IntToPtr->getType(), PN.getNumIncomingValues(), PN.getName() + ".ptr");
-
-  InsertNewInstBefore(NewPtrPHI, PN);
-  SmallDenseMap<Value *, Instruction *> Casts;
-  for (unsigned i = 0; i != PN.getNumIncomingValues(); ++i) {
-    auto *IncomingBB = PN.getIncomingBlock(i);
-    auto *IncomingVal = AvailablePtrVals[i];
-
-    if (IncomingVal->getType() == IntToPtr->getType()) {
-      NewPtrPHI->addIncoming(IncomingVal, IncomingBB);
-      continue;
-    }
-
-#ifndef NDEBUG
-    LoadInst *LoadI = dyn_cast<LoadInst>(IncomingVal);
-    assert((isa<PHINode>(IncomingVal) ||
-            IncomingVal->getType()->isPointerTy() ||
-            (LoadI && LoadI->hasOneUse())) &&
-           "Can not replace LoadInst with multiple uses");
-#endif
-    // Need to insert a BitCast.
-    // For an integer Load instruction with a single use, the load + IntToPtr
-    // cast will be simplified into a pointer load:
-    // %v = load i64, i64* %a.ip, align 8
-    // %v.cast = inttoptr i64 %v to float **
-    // ==>
-    // %v.ptrp = bitcast i64 * %a.ip to float **
-    // %v.cast = load float *, float ** %v.ptrp, align 8
-    Instruction *&CI = Casts[IncomingVal];
-    if (!CI) {
-      CI = CastInst::CreateBitOrPointerCast(IncomingVal, IntToPtr->getType(),
-                                            IncomingVal->getName() + ".ptr");
-      if (auto *IncomingI = dyn_cast<Instruction>(IncomingVal)) {
-        BasicBlock::iterator InsertPos(IncomingI);
-        InsertPos++;
-        if (isa<PHINode>(IncomingI))
-          InsertPos = IncomingI->getParent()->getFirstInsertionPt();
-        InsertNewInstBefore(CI, *InsertPos);
-      } else {
-        auto *InsertBB = &IncomingBB->getParent()->getEntryBlock();
-        InsertNewInstBefore(CI, *InsertBB->getFirstInsertionPt());
-      }
-    }
-    NewPtrPHI->addIncoming(CI, IncomingBB);
-  }
-
-  // The PtrToCast + IntToPtr will be simplified later
-  return CastInst::CreateBitOrPointerCast(NewPtrPHI,
-                                          IntToPtr->getOperand(0)->getType());
-}
-
-/// If we have something like phi [add (a,b), add(a,c)] and if a/b/c and the
-/// adds all have a single use, turn this into a phi and a single binop.
-Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
-  Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
-  assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
-  unsigned Opc = FirstInst->getOpcode();
-  Value *LHSVal = FirstInst->getOperand(0);
-  Value *RHSVal = FirstInst->getOperand(1);
-
-  Type *LHSType = LHSVal->getType();
-  Type *RHSType = RHSVal->getType();
-
-  // Scan to see if all operands are the same opcode, and all have one use.
-  for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
-    Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
-    if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
-        // Verify type of the LHS matches so we don't fold cmp's of different
-        // types.
-        I->getOperand(0)->getType() != LHSType ||
-        I->getOperand(1)->getType() != RHSType)
-      return nullptr;
-
-    // If they are CmpInst instructions, check their predicates
-    if (CmpInst *CI = dyn_cast<CmpInst>(I))
-      if (CI->getPredicate() != cast<CmpInst>(FirstInst)->getPredicate())
-        return nullptr;
-
-    // Keep track of which operand needs a phi node.
-    if (I->getOperand(0) != LHSVal) LHSVal = nullptr;
-    if (I->getOperand(1) != RHSVal) RHSVal = nullptr;
-  }
-
-  // If both LHS and RHS would need a PHI, don't do this transformation,
-  // because it would increase the number of PHIs entering the block,
-  // which leads to higher register pressure. This is especially
-  // bad when the PHIs are in the header of a loop.
-  if (!LHSVal && !RHSVal)
-    return nullptr;
-
-  // Otherwise, this is safe to transform!
-
-  Value *InLHS = FirstInst->getOperand(0);
-  Value *InRHS = FirstInst->getOperand(1);
-  PHINode *NewLHS = nullptr, *NewRHS = nullptr;
-  if (!LHSVal) {
-    NewLHS = PHINode::Create(LHSType, PN.getNumIncomingValues(),
-                             FirstInst->getOperand(0)->getName() + ".pn");
-    NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
-    InsertNewInstBefore(NewLHS, PN);
-    LHSVal = NewLHS;
-  }
-
-  if (!RHSVal) {
-    NewRHS = PHINode::Create(RHSType, PN.getNumIncomingValues(),
-                             FirstInst->getOperand(1)->getName() + ".pn");
-    NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
-    InsertNewInstBefore(NewRHS, PN);
-    RHSVal = NewRHS;
-  }
-
-  // Add all operands to the new PHIs.
-  if (NewLHS || NewRHS) {
-    for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-      Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
-      if (NewLHS) {
-        Value *NewInLHS = InInst->getOperand(0);
-        NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
-      }
-      if (NewRHS) {
-        Value *NewInRHS = InInst->getOperand(1);
-        NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
-      }
-    }
-  }
-
-  if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst)) {
-    CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
-                                     LHSVal, RHSVal);
-    PHIArgMergedDebugLoc(NewCI, PN);
-    return NewCI;
-  }
-
-  BinaryOperator *BinOp = cast<BinaryOperator>(FirstInst);
-  BinaryOperator *NewBinOp =
-    BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
-
-  NewBinOp->copyIRFlags(PN.getIncomingValue(0));
-
-  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i)
-    NewBinOp->andIRFlags(PN.getIncomingValue(i));
-
-  PHIArgMergedDebugLoc(NewBinOp, PN);
-  return NewBinOp;
-}
-
-Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
-  GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
-
-  SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
-                                        FirstInst->op_end());
-  // This is true if all GEP bases are allocas and if all indices into them are
-  // constants.
-  bool AllBasePointersAreAllocas = true;
-
-  // We don't want to replace this phi if the replacement would require
-  // more than one phi, which leads to higher register pressure. This is
-  // especially bad when the PHIs are in the header of a loop.
-  bool NeededPhi = false;
-
-  bool AllInBounds = true;
-
-  // Scan to see if all operands are the same opcode, and all have one use.
-  for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
-    GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
-    if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
-      GEP->getNumOperands() != FirstInst->getNumOperands())
-      return nullptr;
-
-    AllInBounds &= GEP->isInBounds();
-
-    // Keep track of whether or not all GEPs are of alloca pointers.
-    if (AllBasePointersAreAllocas &&
-        (!isa<AllocaInst>(GEP->getOperand(0)) ||
-         !GEP->hasAllConstantIndices()))
-      AllBasePointersAreAllocas = false;
-
-    // Compare the operand lists.
-    for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
-      if (FirstInst->getOperand(op) == GEP->getOperand(op))
-        continue;
-
-      // Don't merge two GEPs when two operands differ (introducing phi nodes)
-      // if one of the PHIs has a constant for the index.  The index may be
-      // substantially cheaper to compute for the constants, so making it a
-      // variable index could pessimize the path.  This also handles the case
-      // for struct indices, which must always be constant.
-      if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
-          isa<ConstantInt>(GEP->getOperand(op)))
-        return nullptr;
-
-      if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
-        return nullptr;
-
-      // If we already needed a PHI for an earlier operand, and another operand
-      // also requires a PHI, we'd be introducing more PHIs than we're
-      // eliminating, which increases register pressure on entry to the PHI's
-      // block.
-      if (NeededPhi)
-        return nullptr;
-
-      FixedOperands[op] = nullptr;  // Needs a PHI.
-      NeededPhi = true;
-    }
-  }
-
-  // If all of the base pointers of the PHI'd GEPs are from allocas, don't
-  // bother doing this transformation.  At best, this will just save a bit of
-  // offset calculation, but all the predecessors will have to materialize the
-  // stack address into a register anyway.  We'd actually rather *clone* the
-  // load up into the predecessors so that we have a load of a gep of an alloca,
-  // which can usually all be folded into the load.
-  if (AllBasePointersAreAllocas)
-    return nullptr;
-
-  // Otherwise, this is safe to transform.  Insert PHI nodes for each operand
-  // that is variable.
-  SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
-
-  bool HasAnyPHIs = false;
-  for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
-    if (FixedOperands[i]) continue;  // operand doesn't need a phi.
-    Value *FirstOp = FirstInst->getOperand(i);
-    PHINode *NewPN = PHINode::Create(FirstOp->getType(), e,
-                                     FirstOp->getName()+".pn");
-    InsertNewInstBefore(NewPN, PN);
-
-    NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
-    OperandPhis[i] = NewPN;
-    FixedOperands[i] = NewPN;
-    HasAnyPHIs = true;
-  }
-
-
-  // Add all operands to the new PHIs.
-  if (HasAnyPHIs) {
-    for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-      GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
-      BasicBlock *InBB = PN.getIncomingBlock(i);
-
-      for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
-        if (PHINode *OpPhi = OperandPhis[op])
-          OpPhi->addIncoming(InGEP->getOperand(op), InBB);
-    }
-  }
-
-  Value *Base = FixedOperands[0];
-  GetElementPtrInst *NewGEP =
-      GetElementPtrInst::Create(FirstInst->getSourceElementType(), Base,
-                                makeArrayRef(FixedOperands).slice(1));
-  if (AllInBounds) NewGEP->setIsInBounds();
-  PHIArgMergedDebugLoc(NewGEP, PN);
-  return NewGEP;
-}
-
-
-/// Return true if we know that it is safe to sink the load out of the block
-/// that defines it. This means that it must be obvious the value of the load is
-/// not changed from the point of the load to the end of the block it is in.
-///
-/// Finally, it is safe, but not profitable, to sink a load targeting a
-/// non-address-taken alloca.  Doing so will cause us to not promote the alloca
-/// to a register.
-static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
-  BasicBlock::iterator BBI = L->getIterator(), E = L->getParent()->end();
-
-  for (++BBI; BBI != E; ++BBI)
-    if (BBI->mayWriteToMemory())
-      return false;
-
-  // Check for non-address taken alloca.  If not address-taken already, it isn't
-  // profitable to do this xform.
-  if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
-    bool isAddressTaken = false;
-    for (User *U : AI->users()) {
-      if (isa<LoadInst>(U)) continue;
-      if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
-        // If storing TO the alloca, then the address isn't taken.
-        if (SI->getOperand(1) == AI) continue;
-      }
-      isAddressTaken = true;
-      break;
-    }
-
-    if (!isAddressTaken && AI->isStaticAlloca())
-      return false;
-  }
-
-  // If this load is a load from a GEP with a constant offset from an alloca,
-  // then we don't want to sink it.  In its present form, it will be
-  // load [constant stack offset].  Sinking it will cause us to have to
-  // materialize the stack addresses in each predecessor in a register only to
-  // do a shared load from register in the successor.
-  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
-    if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
-      if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
-        return false;
-
-  return true;
-}
-
-Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
-  LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
-
-  // FIXME: This is overconservative; this transform is allowed in some cases
-  // for atomic operations.
-  if (FirstLI->isAtomic())
-    return nullptr;
-
-  // When processing loads, we need to propagate two bits of information to the
-  // sunk load: whether it is volatile, and what its alignment is.  We currently
-  // don't sink loads when some have their alignment specified and some don't.
-  // visitLoadInst will propagate an alignment onto the load when TD is around,
-  // and if TD isn't around, we can't handle the mixed case.
-  bool isVolatile = FirstLI->isVolatile();
-  unsigned LoadAlignment = FirstLI->getAlignment();
-  unsigned LoadAddrSpace = FirstLI->getPointerAddressSpace();
-
-  // We can't sink the load if the loaded value could be modified between the
-  // load and the PHI.
-  if (FirstLI->getParent() != PN.getIncomingBlock(0) ||
-      !isSafeAndProfitableToSinkLoad(FirstLI))
-    return nullptr;
-
-  // If the PHI is of volatile loads and the load block has multiple
-  // successors, sinking it would remove a load of the volatile value from
-  // the path through the other successor.
-  if (isVolatile &&
-      FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1)
-    return nullptr;
-
-  // Check to see if all arguments are the same operation.
-  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-    LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i));
-    if (!LI || !LI->hasOneUse())
-      return nullptr;
-
-    // We can't sink the load if the loaded value could be modified between
-    // the load and the PHI.
-    if (LI->isVolatile() != isVolatile ||
-        LI->getParent() != PN.getIncomingBlock(i) ||
-        LI->getPointerAddressSpace() != LoadAddrSpace ||
-        !isSafeAndProfitableToSinkLoad(LI))
-      return nullptr;
-
-    // If some of the loads have an alignment specified but not all of them,
-    // we can't do the transformation.
-    if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
-      return nullptr;
-
-    LoadAlignment = std::min(LoadAlignment, LI->getAlignment());
-
-    // If the PHI is of volatile loads and the load block has multiple
-    // successors, sinking it would remove a load of the volatile value from
-    // the path through the other successor.
-    if (isVolatile &&
-        LI->getParent()->getTerminator()->getNumSuccessors() != 1)
-      return nullptr;
-  }
-
-  // Okay, they are all the same operation.  Create a new PHI node of the
-  // correct type, and PHI together all of the LHS's of the instructions.
-  PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(),
-                                   PN.getNumIncomingValues(),
-                                   PN.getName()+".in");
-
-  Value *InVal = FirstLI->getOperand(0);
-  NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
-  LoadInst *NewLI = new LoadInst(NewPN, "", isVolatile, LoadAlignment);
-
-  unsigned KnownIDs[] = {
-    LLVMContext::MD_tbaa,
-    LLVMContext::MD_range,
-    LLVMContext::MD_invariant_load,
-    LLVMContext::MD_alias_scope,
-    LLVMContext::MD_noalias,
-    LLVMContext::MD_nonnull,
-    LLVMContext::MD_align,
-    LLVMContext::MD_dereferenceable,
-    LLVMContext::MD_dereferenceable_or_null,
-    LLVMContext::MD_access_group,
-  };
-
-  for (unsigned ID : KnownIDs)
-    NewLI->setMetadata(ID, FirstLI->getMetadata(ID));
-
-  // Add all operands to the new PHI and combine TBAA metadata.
-  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-    LoadInst *LI = cast<LoadInst>(PN.getIncomingValue(i));
-    combineMetadata(NewLI, LI, KnownIDs, true);
-    Value *NewInVal = LI->getOperand(0);
-    if (NewInVal != InVal)
-      InVal = nullptr;
-    NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
-  }
-
-  if (InVal) {
-    // The new PHI unions all of the same values together.  This is really
-    // common, so we handle it intelligently here for compile-time speed.
-    NewLI->setOperand(0, InVal);
-    delete NewPN;
-  } else {
-    InsertNewInstBefore(NewPN, PN);
-  }
-
-  // If this was a volatile load that we are merging, make sure to loop through
-  // and mark all the input loads as non-volatile.  If we don't do this, we will
-  // insert a new volatile load and the old ones will not be deletable.
-  if (isVolatile)
-    for (Value *IncValue : PN.incoming_values())
-      cast<LoadInst>(IncValue)->setVolatile(false);
-
-  PHIArgMergedDebugLoc(NewLI, PN);
-  return NewLI;
-}
-
-/// TODO: This function could handle other cast types, but then it might
-/// require special-casing a cast from the 'i1' type. See the comment in
-/// FoldPHIArgOpIntoPHI() about pessimizing illegal integer types.
-Instruction *InstCombiner::FoldPHIArgZextsIntoPHI(PHINode &Phi) {
-  // We cannot create a new instruction after the PHI if the terminator is an
-  // EHPad because there is no valid insertion point.
-  if (Instruction *TI = Phi.getParent()->getTerminator())
-    if (TI->isEHPad())
-      return nullptr;
-
-  // Early exit for the common case of a phi with two operands. These are
-  // handled elsewhere. See the comment below where we check the count of zexts
-  // and constants for more details.
-  unsigned NumIncomingValues = Phi.getNumIncomingValues();
-  if (NumIncomingValues < 3)
-    return nullptr;
-
-  // Find the narrower type specified by the first zext.
-  Type *NarrowType = nullptr;
-  for (Value *V : Phi.incoming_values()) {
-    if (auto *Zext = dyn_cast<ZExtInst>(V)) {
-      NarrowType = Zext->getSrcTy();
-      break;
-    }
-  }
-  if (!NarrowType)
-    return nullptr;
-
-  // Walk the phi operands checking that we only have zexts or constants that
-  // we can shrink for free. Store the new operands for the new phi.
-  SmallVector<Value *, 4> NewIncoming;
-  unsigned NumZexts = 0;
-  unsigned NumConsts = 0;
-  for (Value *V : Phi.incoming_values()) {
-    if (auto *Zext = dyn_cast<ZExtInst>(V)) {
-      // All zexts must be identical and have one use.
-      if (Zext->getSrcTy() != NarrowType || !Zext->hasOneUse())
-        return nullptr;
-      NewIncoming.push_back(Zext->getOperand(0));
-      NumZexts++;
-    } else if (auto *C = dyn_cast<Constant>(V)) {
-      // Make sure that constants can fit in the new type.
-      Constant *Trunc = ConstantExpr::getTrunc(C, NarrowType);
-      if (ConstantExpr::getZExt(Trunc, C->getType()) != C)
-        return nullptr;
-      NewIncoming.push_back(Trunc);
-      NumConsts++;
-    } else {
-      // If it's not a cast or a constant, bail out.
-      return nullptr;
-    }
-  }
-
-  // The more common cases of a phi with no constant operands or just one
-  // variable operand are handled by FoldPHIArgOpIntoPHI() and foldOpIntoPhi()
-  // respectively. foldOpIntoPhi() wants to do the opposite transform that is
-  // performed here. It tries to replicate a cast in the phi operand's basic
-  // block to expose other folding opportunities. Thus, InstCombine will
-  // infinite loop without this check.
-  if (NumConsts == 0 || NumZexts < 2)
-    return nullptr;
-
-  // All incoming values are zexts or constants that are safe to truncate.
-  // Create a new phi node of the narrow type, phi together all of the new
-  // operands, and zext the result back to the original type.
-  PHINode *NewPhi = PHINode::Create(NarrowType, NumIncomingValues,
-                                    Phi.getName() + ".shrunk");
-  for (unsigned i = 0; i != NumIncomingValues; ++i)
-    NewPhi->addIncoming(NewIncoming[i], Phi.getIncomingBlock(i));
-
-  InsertNewInstBefore(NewPhi, Phi);
-  return CastInst::CreateZExtOrBitCast(NewPhi, Phi.getType());
-}
-
-/// If all operands to a PHI node are the same "unary" operator and they all are
-/// only used by the PHI, PHI together their inputs, and do the operation once,
-/// to the result of the PHI.
-Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
-  // We cannot create a new instruction after the PHI if the terminator is an
-  // EHPad because there is no valid insertion point.
-  if (Instruction *TI = PN.getParent()->getTerminator())
-    if (TI->isEHPad())
-      return nullptr;
-
-  Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
-
-  if (isa<GetElementPtrInst>(FirstInst))
-    return FoldPHIArgGEPIntoPHI(PN);
-  if (isa<LoadInst>(FirstInst))
-    return FoldPHIArgLoadIntoPHI(PN);
-
-  // Scan the instruction, looking for input operations that can be folded away.
-  // If all input operands to the phi are the same instruction (e.g. a cast from
-  // the same type or "+42") we can pull the operation through the PHI, reducing
-  // code size and simplifying code.
-  Constant *ConstantOp = nullptr;
-  Type *CastSrcTy = nullptr;
-
-  if (isa<CastInst>(FirstInst)) {
-    CastSrcTy = FirstInst->getOperand(0)->getType();
-
-    // Be careful about transforming integer PHIs.  We don't want to pessimize
-    // the code by turning an i32 into an i1293.
-    if (PN.getType()->isIntegerTy() && CastSrcTy->isIntegerTy()) {
-      if (!shouldChangeType(PN.getType(), CastSrcTy))
-        return nullptr;
-    }
-  } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
-    // Can fold binop, compare or shift here if the RHS is a constant,
-    // otherwise call FoldPHIArgBinOpIntoPHI.
-    ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
-    if (!ConstantOp)
-      return FoldPHIArgBinOpIntoPHI(PN);
-  } else {
-    return nullptr;  // Cannot fold this operation.
-  }
-
-  // Check to see if all arguments are the same operation.
-  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-    Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
-    if (!I || !I->hasOneUse() || !I->isSameOperationAs(FirstInst))
-      return nullptr;
-    if (CastSrcTy) {
-      if (I->getOperand(0)->getType() != CastSrcTy)
-        return nullptr;  // Cast operation must match.
-    } else if (I->getOperand(1) != ConstantOp) {
-      return nullptr;
-    }
-  }
-
-  // Okay, they are all the same operation.  Create a new PHI node of the
-  // correct type, and PHI together all of the LHS's of the instructions.
-  PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
-                                   PN.getNumIncomingValues(),
-                                   PN.getName()+".in");
-
-  Value *InVal = FirstInst->getOperand(0);
-  NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
-
-  // Add all operands to the new PHI.
-  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-    Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
-    if (NewInVal != InVal)
-      InVal = nullptr;
-    NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
-  }
-
-  Value *PhiVal;
-  if (InVal) {
-    // The new PHI unions all of the same values together.  This is really
-    // common, so we handle it intelligently here for compile-time speed.
-    PhiVal = InVal;
-    delete NewPN;
-  } else {
-    InsertNewInstBefore(NewPN, PN);
-    PhiVal = NewPN;
-  }
-
-  // Insert and return the new operation.
-  if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst)) {
-    CastInst *NewCI = CastInst::Create(FirstCI->getOpcode(), PhiVal,
-                                       PN.getType());
-    PHIArgMergedDebugLoc(NewCI, PN);
-    return NewCI;
-  }
-
-  if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) {
-    BinOp = BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
-    BinOp->copyIRFlags(PN.getIncomingValue(0));
-
-    for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i)
-      BinOp->andIRFlags(PN.getIncomingValue(i));
-
-    PHIArgMergedDebugLoc(BinOp, PN);
-    return BinOp;
-  }
-
-  CmpInst *CIOp = cast<CmpInst>(FirstInst);
-  CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
-                                   PhiVal, ConstantOp);
-  PHIArgMergedDebugLoc(NewCI, PN);
-  return NewCI;
-}
-
-/// Return true if this PHI node is only used by a PHI node cycle that is dead.
-static bool DeadPHICycle(PHINode *PN,
-                         SmallPtrSetImpl<PHINode*> &PotentiallyDeadPHIs) {
-  if (PN->use_empty()) return true;
-  if (!PN->hasOneUse()) return false;
-
-  // Remember this node, and if we find the cycle, return.
-  if (!PotentiallyDeadPHIs.insert(PN).second)
-    return true;
-
-  // Don't scan crazily complex things.
-  if (PotentiallyDeadPHIs.size() == 16)
-    return false;
-
-  if (PHINode *PU = dyn_cast<PHINode>(PN->user_back()))
-    return DeadPHICycle(PU, PotentiallyDeadPHIs);
-
-  return false;
-}
-
-/// Return true if this phi node is always equal to NonPhiInVal.
-/// This happens with mutually cyclic phi nodes like:
-///   z = some value; x = phi (y, z); y = phi (x, z)
-static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
-                           SmallPtrSetImpl<PHINode*> &ValueEqualPHIs) {
-  // See if we already saw this PHI node.
-  if (!ValueEqualPHIs.insert(PN).second)
-    return true;
-
-  // Don't scan crazily complex things.
-  if (ValueEqualPHIs.size() == 16)
-    return false;
-
-  // Scan the operands to see if they are either phi nodes or are equal to
-  // the value.
-  for (Value *Op : PN->incoming_values()) {
-    if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
-      if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
-        return false;
-    } else if (Op != NonPhiInVal)
-      return false;
-  }
-
-  return true;
-}
-
-/// Return an existing non-zero constant if this phi node has one, otherwise
-/// return constant 1.
-static ConstantInt *GetAnyNonZeroConstInt(PHINode &PN) {
-  assert(isa<IntegerType>(PN.getType()) && "Expect only integer type phi");
-  for (Value *V : PN.operands())
-    if (auto *ConstVA = dyn_cast<ConstantInt>(V))
-      if (!ConstVA->isZero())
-        return ConstVA;
-  return ConstantInt::get(cast<IntegerType>(PN.getType()), 1);
-}
-
-namespace {
-struct PHIUsageRecord {
-  unsigned PHIId;     // The ID # of the PHI (something determinstic to sort on)
-  unsigned Shift;     // The amount shifted.
-  Instruction *Inst;  // The trunc instruction.
-
-  PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User)
-    : PHIId(pn), Shift(Sh), Inst(User) {}
-
-  bool operator<(const PHIUsageRecord &RHS) const {
-    if (PHIId < RHS.PHIId) return true;
-    if (PHIId > RHS.PHIId) return false;
-    if (Shift < RHS.Shift) return true;
-    if (Shift > RHS.Shift) return false;
-    return Inst->getType()->getPrimitiveSizeInBits() <
-           RHS.Inst->getType()->getPrimitiveSizeInBits();
-  }
-};
-
-struct LoweredPHIRecord {
-  PHINode *PN;        // The PHI that was lowered.
-  unsigned Shift;     // The amount shifted.
-  unsigned Width;     // The width extracted.
-
-  LoweredPHIRecord(PHINode *pn, unsigned Sh, Type *Ty)
-    : PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {}
-
-  // Ctor form used by DenseMap.
-  LoweredPHIRecord(PHINode *pn, unsigned Sh)
-    : PN(pn), Shift(Sh), Width(0) {}
-};
-}
-
-namespace llvm {
-  template<>
-  struct DenseMapInfo<LoweredPHIRecord> {
-    static inline LoweredPHIRecord getEmptyKey() {
-      return LoweredPHIRecord(nullptr, 0);
-    }
-    static inline LoweredPHIRecord getTombstoneKey() {
-      return LoweredPHIRecord(nullptr, 1);
-    }
-    static unsigned getHashValue(const LoweredPHIRecord &Val) {
-      return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^
-             (Val.Width>>3);
-    }
-    static bool isEqual(const LoweredPHIRecord &LHS,
-                        const LoweredPHIRecord &RHS) {
-      return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift &&
-             LHS.Width == RHS.Width;
-    }
-  };
-}
-
-
-/// This is an integer PHI and we know that it has an illegal type: see if it is
-/// only used by trunc or trunc(lshr) operations. If so, we split the PHI into
-/// the various pieces being extracted. This sort of thing is introduced when
-/// SROA promotes an aggregate to large integer values.
-///
-/// TODO: The user of the trunc may be an bitcast to float/double/vector or an
-/// inttoptr.  We should produce new PHIs in the right type.
-///
-Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
-  // PHIUsers - Keep track of all of the truncated values extracted from a set
-  // of PHIs, along with their offset.  These are the things we want to rewrite.
-  SmallVector<PHIUsageRecord, 16> PHIUsers;
-
-  // PHIs are often mutually cyclic, so we keep track of a whole set of PHI
-  // nodes which are extracted from. PHIsToSlice is a set we use to avoid
-  // revisiting PHIs, PHIsInspected is a ordered list of PHIs that we need to
-  // check the uses of (to ensure they are all extracts).
-  SmallVector<PHINode*, 8> PHIsToSlice;
-  SmallPtrSet<PHINode*, 8> PHIsInspected;
-
-  PHIsToSlice.push_back(&FirstPhi);
-  PHIsInspected.insert(&FirstPhi);
-
-  for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) {
-    PHINode *PN = PHIsToSlice[PHIId];
-
-    // Scan the input list of the PHI.  If any input is an invoke, and if the
-    // input is defined in the predecessor, then we won't be split the critical
-    // edge which is required to insert a truncate.  Because of this, we have to
-    // bail out.
-    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
-      InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i));
-      if (!II) continue;
-      if (II->getParent() != PN->getIncomingBlock(i))
-        continue;
-
-      // If we have a phi, and if it's directly in the predecessor, then we have
-      // a critical edge where we need to put the truncate.  Since we can't
-      // split the edge in instcombine, we have to bail out.
-      return nullptr;
-    }
-
-    for (User *U : PN->users()) {
-      Instruction *UserI = cast<Instruction>(U);
-
-      // If the user is a PHI, inspect its uses recursively.
-      if (PHINode *UserPN = dyn_cast<PHINode>(UserI)) {
-        if (PHIsInspected.insert(UserPN).second)
-          PHIsToSlice.push_back(UserPN);
-        continue;
-      }
-
-      // Truncates are always ok.
-      if (isa<TruncInst>(UserI)) {
-        PHIUsers.push_back(PHIUsageRecord(PHIId, 0, UserI));
-        continue;
-      }
-
-      // Otherwise it must be a lshr which can only be used by one trunc.
-      if (UserI->getOpcode() != Instruction::LShr ||
-          !UserI->hasOneUse() || !isa<TruncInst>(UserI->user_back()) ||
-          !isa<ConstantInt>(UserI->getOperand(1)))
-        return nullptr;
-
-      unsigned Shift = cast<ConstantInt>(UserI->getOperand(1))->getZExtValue();
-      PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, UserI->user_back()));
-    }
-  }
-
-  // If we have no users, they must be all self uses, just nuke the PHI.
-  if (PHIUsers.empty())
-    return replaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType()));
-
-  // If this phi node is transformable, create new PHIs for all the pieces
-  // extracted out of it.  First, sort the users by their offset and size.
-  array_pod_sort(PHIUsers.begin(), PHIUsers.end());
-
-  LLVM_DEBUG(dbgs() << "SLICING UP PHI: " << FirstPhi << '\n';
-             for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i) dbgs()
-             << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] << '\n';);
-
-  // PredValues - This is a temporary used when rewriting PHI nodes.  It is
-  // hoisted out here to avoid construction/destruction thrashing.
-  DenseMap<BasicBlock*, Value*> PredValues;
-
-  // ExtractedVals - Each new PHI we introduce is saved here so we don't
-  // introduce redundant PHIs.
-  DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals;
-
-  for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) {
-    unsigned PHIId = PHIUsers[UserI].PHIId;
-    PHINode *PN = PHIsToSlice[PHIId];
-    unsigned Offset = PHIUsers[UserI].Shift;
-    Type *Ty = PHIUsers[UserI].Inst->getType();
-
-    PHINode *EltPHI;
-
-    // If we've already lowered a user like this, reuse the previously lowered
-    // value.
-    if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == nullptr) {
-
-      // Otherwise, Create the new PHI node for this user.
-      EltPHI = PHINode::Create(Ty, PN->getNumIncomingValues(),
-                               PN->getName()+".off"+Twine(Offset), PN);
-      assert(EltPHI->getType() != PN->getType() &&
-             "Truncate didn't shrink phi?");
-
-      for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
-        BasicBlock *Pred = PN->getIncomingBlock(i);
-        Value *&PredVal = PredValues[Pred];
-
-        // If we already have a value for this predecessor, reuse it.
-        if (PredVal) {
-          EltPHI->addIncoming(PredVal, Pred);
-          continue;
-        }
-
-        // Handle the PHI self-reuse case.
-        Value *InVal = PN->getIncomingValue(i);
-        if (InVal == PN) {
-          PredVal = EltPHI;
-          EltPHI->addIncoming(PredVal, Pred);
-          continue;
-        }
-
-        if (PHINode *InPHI = dyn_cast<PHINode>(PN)) {
-          // If the incoming value was a PHI, and if it was one of the PHIs we
-          // already rewrote it, just use the lowered value.
-          if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) {
-            PredVal = Res;
-            EltPHI->addIncoming(PredVal, Pred);
-            continue;
-          }
-        }
-
-        // Otherwise, do an extract in the predecessor.
-        Builder.SetInsertPoint(Pred->getTerminator());
-        Value *Res = InVal;
-        if (Offset)
-          Res = Builder.CreateLShr(Res, ConstantInt::get(InVal->getType(),
-                                                          Offset), "extract");
-        Res = Builder.CreateTrunc(Res, Ty, "extract.t");
-        PredVal = Res;
-        EltPHI->addIncoming(Res, Pred);
-
-        // If the incoming value was a PHI, and if it was one of the PHIs we are
-        // rewriting, we will ultimately delete the code we inserted.  This
-        // means we need to revisit that PHI to make sure we extract out the
-        // needed piece.
-        if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i)))
-          if (PHIsInspected.count(OldInVal)) {
-            unsigned RefPHIId =
-                find(PHIsToSlice, OldInVal) - PHIsToSlice.begin();
-            PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset,
-                                              cast<Instruction>(Res)));
-            ++UserE;
-          }
-      }
-      PredValues.clear();
-
-      LLVM_DEBUG(dbgs() << "  Made element PHI for offset " << Offset << ": "
-                        << *EltPHI << '\n');
-      ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI;
-    }
-
-    // Replace the use of this piece with the PHI node.
-    replaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
-  }
-
-  // Replace all the remaining uses of the PHI nodes (self uses and the lshrs)
-  // with undefs.
-  Value *Undef = UndefValue::get(FirstPhi.getType());
-  for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
-    replaceInstUsesWith(*PHIsToSlice[i], Undef);
-  return replaceInstUsesWith(FirstPhi, Undef);
-}
-
-// PHINode simplification
-//
-Instruction *InstCombiner::visitPHINode(PHINode &PN) {
-  if (Value *V = SimplifyInstruction(&PN, SQ.getWithInstruction(&PN)))
-    return replaceInstUsesWith(PN, V);
-
-  if (Instruction *Result = FoldPHIArgZextsIntoPHI(PN))
-    return Result;
-
-  // If all PHI operands are the same operation, pull them through the PHI,
-  // reducing code size.
-  if (isa<Instruction>(PN.getIncomingValue(0)) &&
-      isa<Instruction>(PN.getIncomingValue(1)) &&
-      cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
-      cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
-      // FIXME: The hasOneUse check will fail for PHIs that use the value more
-      // than themselves more than once.
-      PN.getIncomingValue(0)->hasOneUse())
-    if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
-      return Result;
-
-  // If this is a trivial cycle in the PHI node graph, remove it.  Basically, if
-  // this PHI only has a single use (a PHI), and if that PHI only has one use (a
-  // PHI)... break the cycle.
-  if (PN.hasOneUse()) {
-    if (Instruction *Result = FoldIntegerTypedPHI(PN))
-      return Result;
-
-    Instruction *PHIUser = cast<Instruction>(PN.user_back());
-    if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
-      SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
-      PotentiallyDeadPHIs.insert(&PN);
-      if (DeadPHICycle(PU, PotentiallyDeadPHIs))
-        return replaceInstUsesWith(PN, UndefValue::get(PN.getType()));
-    }
-
-    // If this phi has a single use, and if that use just computes a value for
-    // the next iteration of a loop, delete the phi.  This occurs with unused
-    // induction variables, e.g. "for (int j = 0; ; ++j);".  Detecting this
-    // common case here is good because the only other things that catch this
-    // are induction variable analysis (sometimes) and ADCE, which is only run
-    // late.
-    if (PHIUser->hasOneUse() &&
-        (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
-        PHIUser->user_back() == &PN) {
-      return replaceInstUsesWith(PN, UndefValue::get(PN.getType()));
-    }
-    // When a PHI is used only to be compared with zero, it is safe to replace
-    // an incoming value proved as known nonzero with any non-zero constant.
-    // For example, in the code below, the incoming value %v can be replaced
-    // with any non-zero constant based on the fact that the PHI is only used to
-    // be compared with zero and %v is a known non-zero value:
-    // %v = select %cond, 1, 2
-    // %p = phi [%v, BB] ...
-    //      icmp eq, %p, 0
-    auto *CmpInst = dyn_cast<ICmpInst>(PHIUser);
-    // FIXME: To be simple, handle only integer type for now.
-    if (CmpInst && isa<IntegerType>(PN.getType()) && CmpInst->isEquality() &&
-        match(CmpInst->getOperand(1), m_Zero())) {
-      ConstantInt *NonZeroConst = nullptr;
-      for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
-        Instruction *CtxI = PN.getIncomingBlock(i)->getTerminator();
-        Value *VA = PN.getIncomingValue(i);
-        if (isKnownNonZero(VA, DL, 0, &AC, CtxI, &DT)) {
-          if (!NonZeroConst)
-            NonZeroConst = GetAnyNonZeroConstInt(PN);
-          PN.setIncomingValue(i, NonZeroConst);
-        }
-      }
-    }
-  }
-
-  // We sometimes end up with phi cycles that non-obviously end up being the
-  // same value, for example:
-  //   z = some value; x = phi (y, z); y = phi (x, z)
-  // where the phi nodes don't necessarily need to be in the same block.  Do a
-  // quick check to see if the PHI node only contains a single non-phi value, if
-  // so, scan to see if the phi cycle is actually equal to that value.
-  {
-    unsigned InValNo = 0, NumIncomingVals = PN.getNumIncomingValues();
-    // Scan for the first non-phi operand.
-    while (InValNo != NumIncomingVals &&
-           isa<PHINode>(PN.getIncomingValue(InValNo)))
-      ++InValNo;
-
-    if (InValNo != NumIncomingVals) {
-      Value *NonPhiInVal = PN.getIncomingValue(InValNo);
-
-      // Scan the rest of the operands to see if there are any conflicts, if so
-      // there is no need to recursively scan other phis.
-      for (++InValNo; InValNo != NumIncomingVals; ++InValNo) {
-        Value *OpVal = PN.getIncomingValue(InValNo);
-        if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
-          break;
-      }
-
-      // If we scanned over all operands, then we have one unique value plus
-      // phi values.  Scan PHI nodes to see if they all merge in each other or
-      // the value.
-      if (InValNo == NumIncomingVals) {
-        SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
-        if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
-          return replaceInstUsesWith(PN, NonPhiInVal);
-      }
-    }
-  }
-
-  // If there are multiple PHIs, sort their operands so that they all list
-  // the blocks in the same order. This will help identical PHIs be eliminated
-  // by other passes. Other passes shouldn't depend on this for correctness
-  // however.
-  PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
-  if (&PN != FirstPN)
-    for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) {
-      BasicBlock *BBA = PN.getIncomingBlock(i);
-      BasicBlock *BBB = FirstPN->getIncomingBlock(i);
-      if (BBA != BBB) {
-        Value *VA = PN.getIncomingValue(i);
-        unsigned j = PN.getBasicBlockIndex(BBB);
-        Value *VB = PN.getIncomingValue(j);
-        PN.setIncomingBlock(i, BBB);
-        PN.setIncomingValue(i, VB);
-        PN.setIncomingBlock(j, BBA);
-        PN.setIncomingValue(j, VA);
-        // NOTE: Instcombine normally would want us to "return &PN" if we
-        // modified any of the operands of an instruction.  However, since we
-        // aren't adding or removing uses (just rearranging them) we don't do
-        // this in this case.
-      }
-    }
-
-  // If this is an integer PHI and we know that it has an illegal type, see if
-  // it is only used by trunc or trunc(lshr) operations.  If so, we split the
-  // PHI into the various pieces being extracted.  This sort of thing is
-  // introduced when SROA promotes an aggregate to a single large integer type.
-  if (PN.getType()->isIntegerTy() &&
-      !DL.isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
-    if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
-      return Res;
-
-  return nullptr;
-}