Remove LLVM 8.0.1 files.

1 files changed, 0 insertions, 967 deletions

diff --git a/gnu/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp b/gnu/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
deleted file mode 100644
index beac0d967a9..00000000000
--- a/gnu/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
+++ /dev/null
@@ -1,967 +0,0 @@
-//===- ConstantHoisting.cpp - Prepare code for expensive constants --------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass identifies expensive constants to hoist and coalesces them to
-// better prepare it for SelectionDAG-based code generation. This works around
-// the limitations of the basic-block-at-a-time approach.
-//
-// First it scans all instructions for integer constants and calculates its
-// cost. If the constant can be folded into the instruction (the cost is
-// TCC_Free) or the cost is just a simple operation (TCC_BASIC), then we don't
-// consider it expensive and leave it alone. This is the default behavior and
-// the default implementation of getIntImmCost will always return TCC_Free.
-//
-// If the cost is more than TCC_BASIC, then the integer constant can't be folded
-// into the instruction and it might be beneficial to hoist the constant.
-// Similar constants are coalesced to reduce register pressure and
-// materialization code.
-//
-// When a constant is hoisted, it is also hidden behind a bitcast to force it to
-// be live-out of the basic block. Otherwise the constant would be just
-// duplicated and each basic block would have its own copy in the SelectionDAG.
-// The SelectionDAG recognizes such constants as opaque and doesn't perform
-// certain transformations on them, which would create a new expensive constant.
-//
-// This optimization is only applied to integer constants in instructions and
-// simple (this means not nested) constant cast expressions. For example:
-// %0 = load i64* inttoptr (i64 big_constant to i64*)
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/Scalar/ConstantHoisting.h"
-#include "llvm/ADT/APInt.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/None.h"
-#include "llvm/ADT/Optional.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/BlockFrequencyInfo.h"
-#include "llvm/Analysis/TargetTransformInfo.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/IR/BasicBlock.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/DebugInfoMetadata.h"
-#include "llvm/IR/Dominators.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/InstrTypes.h"
-#include "llvm/IR/Instruction.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/Value.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/BlockFrequency.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/Scalar.h"
-#include <algorithm>
-#include <cassert>
-#include <cstdint>
-#include <iterator>
-#include <tuple>
-#include <utility>
-
-using namespace llvm;
-using namespace consthoist;
-
-#define DEBUG_TYPE "consthoist"
-
-STATISTIC(NumConstantsHoisted, "Number of constants hoisted");
-STATISTIC(NumConstantsRebased, "Number of constants rebased");
-
-static cl::opt<bool> ConstHoistWithBlockFrequency(
-    "consthoist-with-block-frequency", cl::init(true), cl::Hidden,
-    cl::desc("Enable the use of the block frequency analysis to reduce the "
-             "chance to execute const materialization more frequently than "
-             "without hoisting."));
-
-static cl::opt<bool> ConstHoistGEP(
-    "consthoist-gep", cl::init(false), cl::Hidden,
-    cl::desc("Try hoisting constant gep expressions"));
-
-static cl::opt<unsigned>
-MinNumOfDependentToRebase("consthoist-min-num-to-rebase",
-    cl::desc("Do not rebase if number of dependent constants of a Base is less "
-             "than this number."),
-    cl::init(0), cl::Hidden);
-
-namespace {
-
-/// The constant hoisting pass.
-class ConstantHoistingLegacyPass : public FunctionPass {
-public:
-  static char ID; // Pass identification, replacement for typeid
-
-  ConstantHoistingLegacyPass() : FunctionPass(ID) {
-    initializeConstantHoistingLegacyPassPass(*PassRegistry::getPassRegistry());
-  }
-
-  bool runOnFunction(Function &Fn) override;
-
-  StringRef getPassName() const override { return "Constant Hoisting"; }
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesCFG();
-    if (ConstHoistWithBlockFrequency)
-      AU.addRequired<BlockFrequencyInfoWrapperPass>();
-    AU.addRequired<DominatorTreeWrapperPass>();
-    AU.addRequired<TargetTransformInfoWrapperPass>();
-  }
-
-  void releaseMemory() override { Impl.releaseMemory(); }
-
-private:
-  ConstantHoistingPass Impl;
-};
-
-} // end anonymous namespace
-
-char ConstantHoistingLegacyPass::ID = 0;
-
-INITIALIZE_PASS_BEGIN(ConstantHoistingLegacyPass, "consthoist",
-                      "Constant Hoisting", false, false)
-INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
-INITIALIZE_PASS_END(ConstantHoistingLegacyPass, "consthoist",
-                    "Constant Hoisting", false, false)
-
-FunctionPass *llvm::createConstantHoistingPass() {
-  return new ConstantHoistingLegacyPass();
-}
-
-/// Perform the constant hoisting optimization for the given function.
-bool ConstantHoistingLegacyPass::runOnFunction(Function &Fn) {
-  if (skipFunction(Fn))
-    return false;
-
-  LLVM_DEBUG(dbgs() << "********** Begin Constant Hoisting **********\n");
-  LLVM_DEBUG(dbgs() << "********** Function: " << Fn.getName() << '\n');
-
-  bool MadeChange =
-      Impl.runImpl(Fn, getAnalysis<TargetTransformInfoWrapperPass>().getTTI(Fn),
-                   getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
-                   ConstHoistWithBlockFrequency
-                       ? &getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI()
-                       : nullptr,
-                   Fn.getEntryBlock());
-
-  if (MadeChange) {
-    LLVM_DEBUG(dbgs() << "********** Function after Constant Hoisting: "
-                      << Fn.getName() << '\n');
-    LLVM_DEBUG(dbgs() << Fn);
-  }
-  LLVM_DEBUG(dbgs() << "********** End Constant Hoisting **********\n");
-
-  return MadeChange;
-}
-
-/// Find the constant materialization insertion point.
-Instruction *ConstantHoistingPass::findMatInsertPt(Instruction *Inst,
-                                                   unsigned Idx) const {
-  // If the operand is a cast instruction, then we have to materialize the
-  // constant before the cast instruction.
-  if (Idx != ~0U) {
-    Value *Opnd = Inst->getOperand(Idx);
-    if (auto CastInst = dyn_cast<Instruction>(Opnd))
-      if (CastInst->isCast())
-        return CastInst;
-  }
-
-  // The simple and common case. This also includes constant expressions.
-  if (!isa<PHINode>(Inst) && !Inst->isEHPad())
-    return Inst;
-
-  // We can't insert directly before a phi node or an eh pad. Insert before
-  // the terminator of the incoming or dominating block.
-  assert(Entry != Inst->getParent() && "PHI or landing pad in entry block!");
-  if (Idx != ~0U && isa<PHINode>(Inst))
-    return cast<PHINode>(Inst)->getIncomingBlock(Idx)->getTerminator();
-
-  // This must be an EH pad. Iterate over immediate dominators until we find a
-  // non-EH pad. We need to skip over catchswitch blocks, which are both EH pads
-  // and terminators.
-  auto IDom = DT->getNode(Inst->getParent())->getIDom();
-  while (IDom->getBlock()->isEHPad()) {
-    assert(Entry != IDom->getBlock() && "eh pad in entry block");
-    IDom = IDom->getIDom();
-  }
-
-  return IDom->getBlock()->getTerminator();
-}
-
-/// Given \p BBs as input, find another set of BBs which collectively
-/// dominates \p BBs and have the minimal sum of frequencies. Return the BB
-/// set found in \p BBs.
-static void findBestInsertionSet(DominatorTree &DT, BlockFrequencyInfo &BFI,
-                                 BasicBlock *Entry,
-                                 SmallPtrSet<BasicBlock *, 8> &BBs) {
-  assert(!BBs.count(Entry) && "Assume Entry is not in BBs");
-  // Nodes on the current path to the root.
-  SmallPtrSet<BasicBlock *, 8> Path;
-  // Candidates includes any block 'BB' in set 'BBs' that is not strictly
-  // dominated by any other blocks in set 'BBs', and all nodes in the path
-  // in the dominator tree from Entry to 'BB'.
-  SmallPtrSet<BasicBlock *, 16> Candidates;
-  for (auto BB : BBs) {
-    Path.clear();
-    // Walk up the dominator tree until Entry or another BB in BBs
-    // is reached. Insert the nodes on the way to the Path.
-    BasicBlock *Node = BB;
-    // The "Path" is a candidate path to be added into Candidates set.
-    bool isCandidate = false;
-    do {
-      Path.insert(Node);
-      if (Node == Entry || Candidates.count(Node)) {
-        isCandidate = true;
-        break;
-      }
-      assert(DT.getNode(Node)->getIDom() &&
-             "Entry doens't dominate current Node");
-      Node = DT.getNode(Node)->getIDom()->getBlock();
-    } while (!BBs.count(Node));
-
-    // If isCandidate is false, Node is another Block in BBs dominating
-    // current 'BB'. Drop the nodes on the Path.
-    if (!isCandidate)
-      continue;
-
-    // Add nodes on the Path into Candidates.
-    Candidates.insert(Path.begin(), Path.end());
-  }
-
-  // Sort the nodes in Candidates in top-down order and save the nodes
-  // in Orders.
-  unsigned Idx = 0;
-  SmallVector<BasicBlock *, 16> Orders;
-  Orders.push_back(Entry);
-  while (Idx != Orders.size()) {
-    BasicBlock *Node = Orders[Idx++];
-    for (auto ChildDomNode : DT.getNode(Node)->getChildren()) {
-      if (Candidates.count(ChildDomNode->getBlock()))
-        Orders.push_back(ChildDomNode->getBlock());
-    }
-  }
-
-  // Visit Orders in bottom-up order.
-  using InsertPtsCostPair =
-      std::pair<SmallPtrSet<BasicBlock *, 16>, BlockFrequency>;
-
-  // InsertPtsMap is a map from a BB to the best insertion points for the
-  // subtree of BB (subtree not including the BB itself).
-  DenseMap<BasicBlock *, InsertPtsCostPair> InsertPtsMap;
-  InsertPtsMap.reserve(Orders.size() + 1);
-  for (auto RIt = Orders.rbegin(); RIt != Orders.rend(); RIt++) {
-    BasicBlock *Node = *RIt;
-    bool NodeInBBs = BBs.count(Node);
-    SmallPtrSet<BasicBlock *, 16> &InsertPts = InsertPtsMap[Node].first;
-    BlockFrequency &InsertPtsFreq = InsertPtsMap[Node].second;
-
-    // Return the optimal insert points in BBs.
-    if (Node == Entry) {
-      BBs.clear();
-      if (InsertPtsFreq > BFI.getBlockFreq(Node) ||
-          (InsertPtsFreq == BFI.getBlockFreq(Node) && InsertPts.size() > 1))
-        BBs.insert(Entry);
-      else
-        BBs.insert(InsertPts.begin(), InsertPts.end());
-      break;
-    }
-
-    BasicBlock *Parent = DT.getNode(Node)->getIDom()->getBlock();
-    // Initially, ParentInsertPts is empty and ParentPtsFreq is 0. Every child
-    // will update its parent's ParentInsertPts and ParentPtsFreq.
-    SmallPtrSet<BasicBlock *, 16> &ParentInsertPts = InsertPtsMap[Parent].first;
-    BlockFrequency &ParentPtsFreq = InsertPtsMap[Parent].second;
-    // Choose to insert in Node or in subtree of Node.
-    // Don't hoist to EHPad because we may not find a proper place to insert
-    // in EHPad.
-    // If the total frequency of InsertPts is the same as the frequency of the
-    // target Node, and InsertPts contains more than one nodes, choose hoisting
-    // to reduce code size.
-    if (NodeInBBs ||
-        (!Node->isEHPad() &&
-         (InsertPtsFreq > BFI.getBlockFreq(Node) ||
-          (InsertPtsFreq == BFI.getBlockFreq(Node) && InsertPts.size() > 1)))) {
-      ParentInsertPts.insert(Node);
-      ParentPtsFreq += BFI.getBlockFreq(Node);
-    } else {
-      ParentInsertPts.insert(InsertPts.begin(), InsertPts.end());
-      ParentPtsFreq += InsertPtsFreq;
-    }
-  }
-}
-
-/// Find an insertion point that dominates all uses.
-SmallPtrSet<Instruction *, 8> ConstantHoistingPass::findConstantInsertionPoint(
-    const ConstantInfo &ConstInfo) const {
-  assert(!ConstInfo.RebasedConstants.empty() && "Invalid constant info entry.");
-  // Collect all basic blocks.
-  SmallPtrSet<BasicBlock *, 8> BBs;
-  SmallPtrSet<Instruction *, 8> InsertPts;
-  for (auto const &RCI : ConstInfo.RebasedConstants)
-    for (auto const &U : RCI.Uses)
-      BBs.insert(findMatInsertPt(U.Inst, U.OpndIdx)->getParent());
-
-  if (BBs.count(Entry)) {
-    InsertPts.insert(&Entry->front());
-    return InsertPts;
-  }
-
-  if (BFI) {
-    findBestInsertionSet(*DT, *BFI, Entry, BBs);
-    for (auto BB : BBs) {
-      BasicBlock::iterator InsertPt = BB->begin();
-      for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)
-        ;
-      InsertPts.insert(&*InsertPt);
-    }
-    return InsertPts;
-  }
-
-  while (BBs.size() >= 2) {
-    BasicBlock *BB, *BB1, *BB2;
-    BB1 = *BBs.begin();
-    BB2 = *std::next(BBs.begin());
-    BB = DT->findNearestCommonDominator(BB1, BB2);
-    if (BB == Entry) {
-      InsertPts.insert(&Entry->front());
-      return InsertPts;
-    }
-    BBs.erase(BB1);
-    BBs.erase(BB2);
-    BBs.insert(BB);
-  }
-  assert((BBs.size() == 1) && "Expected only one element.");
-  Instruction &FirstInst = (*BBs.begin())->front();
-  InsertPts.insert(findMatInsertPt(&FirstInst));
-  return InsertPts;
-}
-
-/// Record constant integer ConstInt for instruction Inst at operand
-/// index Idx.
-///
-/// The operand at index Idx is not necessarily the constant integer itself. It
-/// could also be a cast instruction or a constant expression that uses the
-/// constant integer.
-void ConstantHoistingPass::collectConstantCandidates(
-    ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx,
-    ConstantInt *ConstInt) {
-  unsigned Cost;
-  // Ask the target about the cost of materializing the constant for the given
-  // instruction and operand index.
-  if (auto IntrInst = dyn_cast<IntrinsicInst>(Inst))
-    Cost = TTI->getIntImmCost(IntrInst->getIntrinsicID(), Idx,
-                              ConstInt->getValue(), ConstInt->getType());
-  else
-    Cost = TTI->getIntImmCost(Inst->getOpcode(), Idx, ConstInt->getValue(),
-                              ConstInt->getType());
-
-  // Ignore cheap integer constants.
-  if (Cost > TargetTransformInfo::TCC_Basic) {
-    ConstCandMapType::iterator Itr;
-    bool Inserted;
-    ConstPtrUnionType Cand = ConstInt;
-    std::tie(Itr, Inserted) = ConstCandMap.insert(std::make_pair(Cand, 0));
-    if (Inserted) {
-      ConstIntCandVec.push_back(ConstantCandidate(ConstInt));
-      Itr->second = ConstIntCandVec.size() - 1;
-    }
-    ConstIntCandVec[Itr->second].addUser(Inst, Idx, Cost);
-    LLVM_DEBUG(if (isa<ConstantInt>(Inst->getOperand(Idx))) dbgs()
-                   << "Collect constant " << *ConstInt << " from " << *Inst
-                   << " with cost " << Cost << '\n';
-               else dbgs() << "Collect constant " << *ConstInt
-                           << " indirectly from " << *Inst << " via "
-                           << *Inst->getOperand(Idx) << " with cost " << Cost
-                           << '\n';);
-  }
-}
-
-/// Record constant GEP expression for instruction Inst at operand index Idx.
-void ConstantHoistingPass::collectConstantCandidates(
-    ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx,
-    ConstantExpr *ConstExpr) {
-  // TODO: Handle vector GEPs
-  if (ConstExpr->getType()->isVectorTy())
-    return;
-
-  GlobalVariable *BaseGV = dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
-  if (!BaseGV)
-    return;
-
-  // Get offset from the base GV.
-  PointerType *GVPtrTy = dyn_cast<PointerType>(BaseGV->getType());
-  IntegerType *PtrIntTy = DL->getIntPtrType(*Ctx, GVPtrTy->getAddressSpace());
-  APInt Offset(DL->getTypeSizeInBits(PtrIntTy), /*val*/0, /*isSigned*/true);
-  auto *GEPO = cast<GEPOperator>(ConstExpr);
-  if (!GEPO->accumulateConstantOffset(*DL, Offset))
-    return;
-
-  if (!Offset.isIntN(32))
-    return;
-
-  // A constant GEP expression that has a GlobalVariable as base pointer is
-  // usually lowered to a load from constant pool. Such operation is unlikely
-  // to be cheaper than compute it by <Base + Offset>, which can be lowered to
-  // an ADD instruction or folded into Load/Store instruction.
-  int Cost = TTI->getIntImmCost(Instruction::Add, 1, Offset, PtrIntTy);
-  ConstCandVecType &ExprCandVec = ConstGEPCandMap[BaseGV];
-  ConstCandMapType::iterator Itr;
-  bool Inserted;
-  ConstPtrUnionType Cand = ConstExpr;
-  std::tie(Itr, Inserted) = ConstCandMap.insert(std::make_pair(Cand, 0));
-  if (Inserted) {
-    ExprCandVec.push_back(ConstantCandidate(
-        ConstantInt::get(Type::getInt32Ty(*Ctx), Offset.getLimitedValue()),
-        ConstExpr));
-    Itr->second = ExprCandVec.size() - 1;
-  }
-  ExprCandVec[Itr->second].addUser(Inst, Idx, Cost);
-}
-
-/// Check the operand for instruction Inst at index Idx.
-void ConstantHoistingPass::collectConstantCandidates(
-    ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx) {
-  Value *Opnd = Inst->getOperand(Idx);
-
-  // Visit constant integers.
-  if (auto ConstInt = dyn_cast<ConstantInt>(Opnd)) {
-    collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
-    return;
-  }
-
-  // Visit cast instructions that have constant integers.
-  if (auto CastInst = dyn_cast<Instruction>(Opnd)) {
-    // Only visit cast instructions, which have been skipped. All other
-    // instructions should have already been visited.
-    if (!CastInst->isCast())
-      return;
-
-    if (auto *ConstInt = dyn_cast<ConstantInt>(CastInst->getOperand(0))) {
-      // Pretend the constant is directly used by the instruction and ignore
-      // the cast instruction.
-      collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
-      return;
-    }
-  }
-
-  // Visit constant expressions that have constant integers.
-  if (auto ConstExpr = dyn_cast<ConstantExpr>(Opnd)) {
-    // Handle constant gep expressions.
-    if (ConstHoistGEP && ConstExpr->isGEPWithNoNotionalOverIndexing())
-      collectConstantCandidates(ConstCandMap, Inst, Idx, ConstExpr);
-
-    // Only visit constant cast expressions.
-    if (!ConstExpr->isCast())
-      return;
-
-    if (auto ConstInt = dyn_cast<ConstantInt>(ConstExpr->getOperand(0))) {
-      // Pretend the constant is directly used by the instruction and ignore
-      // the constant expression.
-      collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
-      return;
-    }
-  }
-}
-
-/// Scan the instruction for expensive integer constants and record them
-/// in the constant candidate vector.
-void ConstantHoistingPass::collectConstantCandidates(
-    ConstCandMapType &ConstCandMap, Instruction *Inst) {
-  // Skip all cast instructions. They are visited indirectly later on.
-  if (Inst->isCast())
-    return;
-
-  // Scan all operands.
-  for (unsigned Idx = 0, E = Inst->getNumOperands(); Idx != E; ++Idx) {
-    // The cost of materializing the constants (defined in
-    // `TargetTransformInfo::getIntImmCost`) for instructions which only take
-    // constant variables is lower than `TargetTransformInfo::TCC_Basic`. So
-    // it's safe for us to collect constant candidates from all IntrinsicInsts.
-    if (canReplaceOperandWithVariable(Inst, Idx) || isa<IntrinsicInst>(Inst)) {
-      collectConstantCandidates(ConstCandMap, Inst, Idx);
-    }
-  } // end of for all operands
-}
-
-/// Collect all integer constants in the function that cannot be folded
-/// into an instruction itself.
-void ConstantHoistingPass::collectConstantCandidates(Function &Fn) {
-  ConstCandMapType ConstCandMap;
-  for (BasicBlock &BB : Fn)
-    for (Instruction &Inst : BB)
-      collectConstantCandidates(ConstCandMap, &Inst);
-}
-
-// This helper function is necessary to deal with values that have different
-// bit widths (APInt Operator- does not like that). If the value cannot be
-// represented in uint64 we return an "empty" APInt. This is then interpreted
-// as the value is not in range.
-static Optional<APInt> calculateOffsetDiff(const APInt &V1, const APInt &V2) {
-  Optional<APInt> Res = None;
-  unsigned BW = V1.getBitWidth() > V2.getBitWidth() ?
-                V1.getBitWidth() : V2.getBitWidth();
-  uint64_t LimVal1 = V1.getLimitedValue();
-  uint64_t LimVal2 = V2.getLimitedValue();
-
-  if (LimVal1 == ~0ULL || LimVal2 == ~0ULL)
-    return Res;
-
-  uint64_t Diff = LimVal1 - LimVal2;
-  return APInt(BW, Diff, true);
-}
-
-// From a list of constants, one needs to picked as the base and the other
-// constants will be transformed into an offset from that base constant. The
-// question is which we can pick best? For example, consider these constants
-// and their number of uses:
-//
-//  Constants| 2 | 4 | 12 | 42 |
-//  NumUses  | 3 | 2 |  8 |  7 |
-//
-// Selecting constant 12 because it has the most uses will generate negative
-// offsets for constants 2 and 4 (i.e. -10 and -8 respectively). If negative
-// offsets lead to less optimal code generation, then there might be better
-// solutions. Suppose immediates in the range of 0..35 are most optimally
-// supported by the architecture, then selecting constant 2 is most optimal
-// because this will generate offsets: 0, 2, 10, 40. Offsets 0, 2 and 10 are in
-// range 0..35, and thus 3 + 2 + 8 = 13 uses are in range. Selecting 12 would
-// have only 8 uses in range, so choosing 2 as a base is more optimal. Thus, in
-// selecting the base constant the range of the offsets is a very important
-// factor too that we take into account here. This algorithm calculates a total
-// costs for selecting a constant as the base and substract the costs if
-// immediates are out of range. It has quadratic complexity, so we call this
-// function only when we're optimising for size and there are less than 100
-// constants, we fall back to the straightforward algorithm otherwise
-// which does not do all the offset calculations.
-unsigned
-ConstantHoistingPass::maximizeConstantsInRange(ConstCandVecType::iterator S,
-                                           ConstCandVecType::iterator E,
-                                           ConstCandVecType::iterator &MaxCostItr) {
-  unsigned NumUses = 0;
-
-  if(!Entry->getParent()->optForSize() || std::distance(S,E) > 100) {
-    for (auto ConstCand = S; ConstCand != E; ++ConstCand) {
-      NumUses += ConstCand->Uses.size();
-      if (ConstCand->CumulativeCost > MaxCostItr->CumulativeCost)
-        MaxCostItr = ConstCand;
-    }
-    return NumUses;
-  }
-
-  LLVM_DEBUG(dbgs() << "== Maximize constants in range ==\n");
-  int MaxCost = -1;
-  for (auto ConstCand = S; ConstCand != E; ++ConstCand) {
-    auto Value = ConstCand->ConstInt->getValue();
-    Type *Ty = ConstCand->ConstInt->getType();
-    int Cost = 0;
-    NumUses += ConstCand->Uses.size();
-    LLVM_DEBUG(dbgs() << "= Constant: " << ConstCand->ConstInt->getValue()
-                      << "\n");
-
-    for (auto User : ConstCand->Uses) {
-      unsigned Opcode = User.Inst->getOpcode();
-      unsigned OpndIdx = User.OpndIdx;
-      Cost += TTI->getIntImmCost(Opcode, OpndIdx, Value, Ty);
-      LLVM_DEBUG(dbgs() << "Cost: " << Cost << "\n");
-
-      for (auto C2 = S; C2 != E; ++C2) {
-        Optional<APInt> Diff = calculateOffsetDiff(
-                                   C2->ConstInt->getValue(),
-                                   ConstCand->ConstInt->getValue());
-        if (Diff) {
-          const int ImmCosts =
-            TTI->getIntImmCodeSizeCost(Opcode, OpndIdx, Diff.getValue(), Ty);
-          Cost -= ImmCosts;
-          LLVM_DEBUG(dbgs() << "Offset " << Diff.getValue() << " "
-                            << "has penalty: " << ImmCosts << "\n"
-                            << "Adjusted cost: " << Cost << "\n");
-        }
-      }
-    }
-    LLVM_DEBUG(dbgs() << "Cumulative cost: " << Cost << "\n");
-    if (Cost > MaxCost) {
-      MaxCost = Cost;
-      MaxCostItr = ConstCand;
-      LLVM_DEBUG(dbgs() << "New candidate: " << MaxCostItr->ConstInt->getValue()
-                        << "\n");
-    }
-  }
-  return NumUses;
-}
-
-/// Find the base constant within the given range and rebase all other
-/// constants with respect to the base constant.
-void ConstantHoistingPass::findAndMakeBaseConstant(
-    ConstCandVecType::iterator S, ConstCandVecType::iterator E,
-    SmallVectorImpl<consthoist::ConstantInfo> &ConstInfoVec) {
-  auto MaxCostItr = S;
-  unsigned NumUses = maximizeConstantsInRange(S, E, MaxCostItr);
-
-  // Don't hoist constants that have only one use.
-  if (NumUses <= 1)
-    return;
-
-  ConstantInt *ConstInt = MaxCostItr->ConstInt;
-  ConstantExpr *ConstExpr = MaxCostItr->ConstExpr;
-  ConstantInfo ConstInfo;
-  ConstInfo.BaseInt = ConstInt;
-  ConstInfo.BaseExpr = ConstExpr;
-  Type *Ty = ConstInt->getType();
-
-  // Rebase the constants with respect to the base constant.
-  for (auto ConstCand = S; ConstCand != E; ++ConstCand) {
-    APInt Diff = ConstCand->ConstInt->getValue() - ConstInt->getValue();
-    Constant *Offset = Diff == 0 ? nullptr : ConstantInt::get(Ty, Diff);
-    Type *ConstTy =
-        ConstCand->ConstExpr ? ConstCand->ConstExpr->getType() : nullptr;
-    ConstInfo.RebasedConstants.push_back(
-      RebasedConstantInfo(std::move(ConstCand->Uses), Offset, ConstTy));
-  }
-  ConstInfoVec.push_back(std::move(ConstInfo));
-}
-
-/// Finds and combines constant candidates that can be easily
-/// rematerialized with an add from a common base constant.
-void ConstantHoistingPass::findBaseConstants(GlobalVariable *BaseGV) {
-  // If BaseGV is nullptr, find base among candidate constant integers;
-  // Otherwise find base among constant GEPs that share the same BaseGV.
-  ConstCandVecType &ConstCandVec = BaseGV ?
-      ConstGEPCandMap[BaseGV] : ConstIntCandVec;
-  ConstInfoVecType &ConstInfoVec = BaseGV ?
-      ConstGEPInfoMap[BaseGV] : ConstIntInfoVec;
-
-  // Sort the constants by value and type. This invalidates the mapping!
-  std::stable_sort(ConstCandVec.begin(), ConstCandVec.end(),
-             [](const ConstantCandidate &LHS, const ConstantCandidate &RHS) {
-    if (LHS.ConstInt->getType() != RHS.ConstInt->getType())
-      return LHS.ConstInt->getType()->getBitWidth() <
-             RHS.ConstInt->getType()->getBitWidth();
-    return LHS.ConstInt->getValue().ult(RHS.ConstInt->getValue());
-  });
-
-  // Simple linear scan through the sorted constant candidate vector for viable
-  // merge candidates.
-  auto MinValItr = ConstCandVec.begin();
-  for (auto CC = std::next(ConstCandVec.begin()), E = ConstCandVec.end();
-       CC != E; ++CC) {
-    if (MinValItr->ConstInt->getType() == CC->ConstInt->getType()) {
-      Type *MemUseValTy = nullptr;
-      for (auto &U : CC->Uses) {
-        auto *UI = U.Inst;
-        if (LoadInst *LI = dyn_cast<LoadInst>(UI)) {
-          MemUseValTy = LI->getType();
-          break;
-        } else if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
-          // Make sure the constant is used as pointer operand of the StoreInst.
-          if (SI->getPointerOperand() == SI->getOperand(U.OpndIdx)) {
-            MemUseValTy = SI->getValueOperand()->getType();
-            break;
-          }
-        }
-      }
-
-      // Check if the constant is in range of an add with immediate.
-      APInt Diff = CC->ConstInt->getValue() - MinValItr->ConstInt->getValue();
-      if ((Diff.getBitWidth() <= 64) &&
-          TTI->isLegalAddImmediate(Diff.getSExtValue()) &&
-          // Check if Diff can be used as offset in addressing mode of the user
-          // memory instruction.
-          (!MemUseValTy || TTI->isLegalAddressingMode(MemUseValTy,
-           /*BaseGV*/nullptr, /*BaseOffset*/Diff.getSExtValue(),
-           /*HasBaseReg*/true, /*Scale*/0)))
-        continue;
-    }
-    // We either have now a different constant type or the constant is not in
-    // range of an add with immediate anymore.
-    findAndMakeBaseConstant(MinValItr, CC, ConstInfoVec);
-    // Start a new base constant search.
-    MinValItr = CC;
-  }
-  // Finalize the last base constant search.
-  findAndMakeBaseConstant(MinValItr, ConstCandVec.end(), ConstInfoVec);
-}
-
-/// Updates the operand at Idx in instruction Inst with the result of
-///        instruction Mat. If the instruction is a PHI node then special
-///        handling for duplicate values form the same incoming basic block is
-///        required.
-/// \return The update will always succeed, but the return value indicated if
-///         Mat was used for the update or not.
-static bool updateOperand(Instruction *Inst, unsigned Idx, Instruction *Mat) {
-  if (auto PHI = dyn_cast<PHINode>(Inst)) {
-    // Check if any previous operand of the PHI node has the same incoming basic
-    // block. This is a very odd case that happens when the incoming basic block
-    // has a switch statement. In this case use the same value as the previous
-    // operand(s), otherwise we will fail verification due to different values.
-    // The values are actually the same, but the variable names are different
-    // and the verifier doesn't like that.
-    BasicBlock *IncomingBB = PHI->getIncomingBlock(Idx);
-    for (unsigned i = 0; i < Idx; ++i) {
-      if (PHI->getIncomingBlock(i) == IncomingBB) {
-        Value *IncomingVal = PHI->getIncomingValue(i);
-        Inst->setOperand(Idx, IncomingVal);
-        return false;
-      }
-    }
-  }
-
-  Inst->setOperand(Idx, Mat);
-  return true;
-}
-
-/// Emit materialization code for all rebased constants and update their
-/// users.
-void ConstantHoistingPass::emitBaseConstants(Instruction *Base,
-                                             Constant *Offset,
-                                             Type *Ty,
-                                             const ConstantUser &ConstUser) {
-  Instruction *Mat = Base;
-
-  // The same offset can be dereferenced to different types in nested struct.
-  if (!Offset && Ty && Ty != Base->getType())
-    Offset = ConstantInt::get(Type::getInt32Ty(*Ctx), 0);
-
-  if (Offset) {
-    Instruction *InsertionPt = findMatInsertPt(ConstUser.Inst,
-                                               ConstUser.OpndIdx);
-    if (Ty) {
-      // Constant being rebased is a ConstantExpr.
-      PointerType *Int8PtrTy = Type::getInt8PtrTy(*Ctx,
-          cast<PointerType>(Ty)->getAddressSpace());
-      Base = new BitCastInst(Base, Int8PtrTy, "base_bitcast", InsertionPt);
-      Mat = GetElementPtrInst::Create(Int8PtrTy->getElementType(), Base,
-          Offset, "mat_gep", InsertionPt);
-      Mat = new BitCastInst(Mat, Ty, "mat_bitcast", InsertionPt);
-    } else
-      // Constant being rebased is a ConstantInt.
-      Mat = BinaryOperator::Create(Instruction::Add, Base, Offset,
-                                 "const_mat", InsertionPt);
-
-    LLVM_DEBUG(dbgs() << "Materialize constant (" << *Base->getOperand(0)
-                      << " + " << *Offset << ") in BB "
-                      << Mat->getParent()->getName() << '\n'
-                      << *Mat << '\n');
-    Mat->setDebugLoc(ConstUser.Inst->getDebugLoc());
-  }
-  Value *Opnd = ConstUser.Inst->getOperand(ConstUser.OpndIdx);
-
-  // Visit constant integer.
-  if (isa<ConstantInt>(Opnd)) {
-    LLVM_DEBUG(dbgs() << "Update: " << *ConstUser.Inst << '\n');
-    if (!updateOperand(ConstUser.Inst, ConstUser.OpndIdx, Mat) && Offset)
-      Mat->eraseFromParent();
-    LLVM_DEBUG(dbgs() << "To    : " << *ConstUser.Inst << '\n');
-    return;
-  }
-
-  // Visit cast instruction.
-  if (auto CastInst = dyn_cast<Instruction>(Opnd)) {
-    assert(CastInst->isCast() && "Expected an cast instruction!");
-    // Check if we already have visited this cast instruction before to avoid
-    // unnecessary cloning.
-    Instruction *&ClonedCastInst = ClonedCastMap[CastInst];
-    if (!ClonedCastInst) {
-      ClonedCastInst = CastInst->clone();
-      ClonedCastInst->setOperand(0, Mat);
-      ClonedCastInst->insertAfter(CastInst);
-      // Use the same debug location as the original cast instruction.
-      ClonedCastInst->setDebugLoc(CastInst->getDebugLoc());
-      LLVM_DEBUG(dbgs() << "Clone instruction: " << *CastInst << '\n'
-                        << "To               : " << *ClonedCastInst << '\n');
-    }
-
-    LLVM_DEBUG(dbgs() << "Update: " << *ConstUser.Inst << '\n');
-    updateOperand(ConstUser.Inst, ConstUser.OpndIdx, ClonedCastInst);
-    LLVM_DEBUG(dbgs() << "To    : " << *ConstUser.Inst << '\n');
-    return;
-  }
-
-  // Visit constant expression.
-  if (auto ConstExpr = dyn_cast<ConstantExpr>(Opnd)) {
-    if (ConstExpr->isGEPWithNoNotionalOverIndexing()) {
-      // Operand is a ConstantGEP, replace it.
-      updateOperand(ConstUser.Inst, ConstUser.OpndIdx, Mat);
-      return;
-    }
-
-    // Aside from constant GEPs, only constant cast expressions are collected.
-    assert(ConstExpr->isCast() && "ConstExpr should be a cast");
-    Instruction *ConstExprInst = ConstExpr->getAsInstruction();
-    ConstExprInst->setOperand(0, Mat);
-    ConstExprInst->insertBefore(findMatInsertPt(ConstUser.Inst,
-                                                ConstUser.OpndIdx));
-
-    // Use the same debug location as the instruction we are about to update.
-    ConstExprInst->setDebugLoc(ConstUser.Inst->getDebugLoc());
-
-    LLVM_DEBUG(dbgs() << "Create instruction: " << *ConstExprInst << '\n'
-                      << "From              : " << *ConstExpr << '\n');
-    LLVM_DEBUG(dbgs() << "Update: " << *ConstUser.Inst << '\n');
-    if (!updateOperand(ConstUser.Inst, ConstUser.OpndIdx, ConstExprInst)) {
-      ConstExprInst->eraseFromParent();
-      if (Offset)
-        Mat->eraseFromParent();
-    }
-    LLVM_DEBUG(dbgs() << "To    : " << *ConstUser.Inst << '\n');
-    return;
-  }
-}
-
-/// Hoist and hide the base constant behind a bitcast and emit
-/// materialization code for derived constants.
-bool ConstantHoistingPass::emitBaseConstants(GlobalVariable *BaseGV) {
-  bool MadeChange = false;
-  SmallVectorImpl<consthoist::ConstantInfo> &ConstInfoVec =
-      BaseGV ? ConstGEPInfoMap[BaseGV] : ConstIntInfoVec;
-  for (auto const &ConstInfo : ConstInfoVec) {
-    SmallPtrSet<Instruction *, 8> IPSet = findConstantInsertionPoint(ConstInfo);
-    assert(!IPSet.empty() && "IPSet is empty");
-
-    unsigned UsesNum = 0;
-    unsigned ReBasesNum = 0;
-    unsigned NotRebasedNum = 0;
-    for (Instruction *IP : IPSet) {
-      // First, collect constants depending on this IP of the base.
-      unsigned Uses = 0;
-      using RebasedUse = std::tuple<Constant *, Type *, ConstantUser>;
-      SmallVector<RebasedUse, 4> ToBeRebased;
-      for (auto const &RCI : ConstInfo.RebasedConstants) {
-        for (auto const &U : RCI.Uses) {
-          Uses++;
-          BasicBlock *OrigMatInsertBB =
-              findMatInsertPt(U.Inst, U.OpndIdx)->getParent();
-          // If Base constant is to be inserted in multiple places,
-          // generate rebase for U using the Base dominating U.
-          if (IPSet.size() == 1 ||
-              DT->dominates(IP->getParent(), OrigMatInsertBB))
-            ToBeRebased.push_back(RebasedUse(RCI.Offset, RCI.Ty, U));
-        }
-      }
-      UsesNum = Uses;
-
-      // If only few constants depend on this IP of base, skip rebasing,
-      // assuming the base and the rebased have the same materialization cost.
-      if (ToBeRebased.size() < MinNumOfDependentToRebase) {
-        NotRebasedNum += ToBeRebased.size();
-        continue;
-      }
-
-      // Emit an instance of the base at this IP.
-      Instruction *Base = nullptr;
-      // Hoist and hide the base constant behind a bitcast.
-      if (ConstInfo.BaseExpr) {
-        assert(BaseGV && "A base constant expression must have an base GV");
-        Type *Ty = ConstInfo.BaseExpr->getType();
-        Base = new BitCastInst(ConstInfo.BaseExpr, Ty, "const", IP);
-      } else {
-        IntegerType *Ty = ConstInfo.BaseInt->getType();
-        Base = new BitCastInst(ConstInfo.BaseInt, Ty, "const", IP);
-      }
-
-      Base->setDebugLoc(IP->getDebugLoc());
-
-      LLVM_DEBUG(dbgs() << "Hoist constant (" << *ConstInfo.BaseInt
-                        << ") to BB " << IP->getParent()->getName() << '\n'
-                        << *Base << '\n');
-
-      // Emit materialization code for rebased constants depending on this IP.
-      for (auto const &R : ToBeRebased) {
-        Constant *Off = std::get<0>(R);
-        Type *Ty = std::get<1>(R);
-        ConstantUser U = std::get<2>(R);
-        emitBaseConstants(Base, Off, Ty, U);
-        ReBasesNum++;
-        // Use the same debug location as the last user of the constant.
-        Base->setDebugLoc(DILocation::getMergedLocation(
-            Base->getDebugLoc(), U.Inst->getDebugLoc()));
-      }
-      assert(!Base->use_empty() && "The use list is empty!?");
-      assert(isa<Instruction>(Base->user_back()) &&
-             "All uses should be instructions.");
-    }
-    (void)UsesNum;
-    (void)ReBasesNum;
-    (void)NotRebasedNum;
-    // Expect all uses are rebased after rebase is done.
-    assert(UsesNum == (ReBasesNum + NotRebasedNum) &&
-           "Not all uses are rebased");
-
-    NumConstantsHoisted++;
-
-    // Base constant is also included in ConstInfo.RebasedConstants, so
-    // deduct 1 from ConstInfo.RebasedConstants.size().
-    NumConstantsRebased += ConstInfo.RebasedConstants.size() - 1;
-
-    MadeChange = true;
-  }
-  return MadeChange;
-}
-
-/// Check all cast instructions we made a copy of and remove them if they
-/// have no more users.
-void ConstantHoistingPass::deleteDeadCastInst() const {
-  for (auto const &I : ClonedCastMap)
-    if (I.first->use_empty())
-      I.first->eraseFromParent();
-}
-
-/// Optimize expensive integer constants in the given function.
-bool ConstantHoistingPass::runImpl(Function &Fn, TargetTransformInfo &TTI,
-                                   DominatorTree &DT, BlockFrequencyInfo *BFI,
-                                   BasicBlock &Entry) {
-  this->TTI = &TTI;
-  this->DT = &DT;
-  this->BFI = BFI;
-  this->DL = &Fn.getParent()->getDataLayout();
-  this->Ctx = &Fn.getContext();
-  this->Entry = &Entry;
-  // Collect all constant candidates.
-  collectConstantCandidates(Fn);
-
-  // Combine constants that can be easily materialized with an add from a common
-  // base constant.
-  if (!ConstIntCandVec.empty())
-    findBaseConstants(nullptr);
-  for (auto &MapEntry : ConstGEPCandMap)
-    if (!MapEntry.second.empty())
-      findBaseConstants(MapEntry.first);
-
-  // Finally hoist the base constant and emit materialization code for dependent
-  // constants.
-  bool MadeChange = false;
-  if (!ConstIntInfoVec.empty())
-    MadeChange = emitBaseConstants(nullptr);
-  for (auto MapEntry : ConstGEPInfoMap)
-    if (!MapEntry.second.empty())
-      MadeChange |= emitBaseConstants(MapEntry.first);
-
-
-  // Cleanup dead instructions.
-  deleteDeadCastInst();
-
-  return MadeChange;
-}
-
-PreservedAnalyses ConstantHoistingPass::run(Function &F,
-                                            FunctionAnalysisManager &AM) {
-  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
-  auto &TTI = AM.getResult<TargetIRAnalysis>(F);
-  auto BFI = ConstHoistWithBlockFrequency
-                 ? &AM.getResult<BlockFrequencyAnalysis>(F)
-                 : nullptr;
-  if (!runImpl(F, TTI, DT, BFI, F.getEntryBlock()))
-    return PreservedAnalyses::all();
-
-  PreservedAnalyses PA;
-  PA.preserveSet<CFGAnalyses>();
-  return PA;
-}