text: //===- MachineFunction.cpp ------------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // Collect native machine code information for a function.  This allows
  // target-specific information about the generated code to be stored with each
  // function.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/CodeGen/MachineFunction.h"
  #include "llvm/ADT/BitVector.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/DenseSet.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/Analysis/ConstantFolding.h"
  #include "llvm/Analysis/EHPersonalities.h"
  #include "llvm/CodeGen/MachineBasicBlock.h"
  #include "llvm/CodeGen/MachineConstantPool.h"
  #include "llvm/CodeGen/MachineFrameInfo.h"
  #include "llvm/CodeGen/MachineInstr.h"
  #include "llvm/CodeGen/MachineJumpTableInfo.h"
  #include "llvm/CodeGen/MachineMemOperand.h"
  #include "llvm/CodeGen/MachineModuleInfo.h"
  #include "llvm/CodeGen/MachineRegisterInfo.h"
  #include "llvm/CodeGen/PseudoSourceValue.h"
  #include "llvm/CodeGen/TargetFrameLowering.h"
  #include "llvm/CodeGen/TargetInstrInfo.h"
  #include "llvm/CodeGen/TargetLowering.h"
  #include "llvm/CodeGen/TargetRegisterInfo.h"
  #include "llvm/CodeGen/TargetSubtargetInfo.h"
  #include "llvm/CodeGen/WasmEHFuncInfo.h"
  #include "llvm/CodeGen/WinEHFuncInfo.h"
  #include "llvm/Config/llvm-config.h"
  #include "llvm/IR/Attributes.h"
  #include "llvm/IR/BasicBlock.h"
  #include "llvm/IR/Constant.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DebugInfoMetadata.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Function.h"
  #include "llvm/IR/GlobalValue.h"
  #include "llvm/IR/Instruction.h"
  #include "llvm/IR/Instructions.h"
  #include "llvm/IR/Metadata.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/ModuleSlotTracker.h"
  #include "llvm/IR/Value.h"
  #include "llvm/MC/MCContext.h"
  #include "llvm/MC/MCSymbol.h"
  #include "llvm/MC/SectionKind.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/DOTGraphTraits.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/GraphWriter.h"
  #include "llvm/Support/raw_ostream.h"
  #include "llvm/Target/TargetMachine.h"
  #include <algorithm>
  #include <cassert>
  #include <cstddef>
  #include <cstdint>
  #include <iterator>
  #include <string>
  #include <type_traits>
  #include <utility>
  #include <vector>
  
  using namespace llvm;
  
  #define DEBUG_TYPE "codegen"
  
  static cl::opt<unsigned> AlignAllFunctions(
      "align-all-functions",
      cl::desc("Force the alignment of all functions in log2 format (e.g. 4 "
               "means align on 16B boundaries)."),
      cl::init(0), cl::Hidden);
  
  static const char *getPropertyName(MachineFunctionProperties::Property Prop) {
    using P = MachineFunctionProperties::Property;
  
    switch(Prop) {
    case P::FailedISel: return "FailedISel";
    case P::IsSSA: return "IsSSA";
    case P::Legalized: return "Legalized";
    case P::NoPHIs: return "NoPHIs";
    case P::NoVRegs: return "NoVRegs";
    case P::RegBankSelected: return "RegBankSelected";
    case P::Selected: return "Selected";
    case P::TracksLiveness: return "TracksLiveness";
    case P::TiedOpsRewritten: return "TiedOpsRewritten";
    }
    llvm_unreachable("Invalid machine function property");
  }
  
  // Pin the vtable to this file.
  void MachineFunction::Delegate::anchor() {}
  
  void MachineFunctionProperties::print(raw_ostream &OS) const {
    const char *Separator = "";
    for (BitVector::size_type I = 0; I < Properties.size(); ++I) {
      if (!Properties[I])
        continue;
      OS << Separator << getPropertyName(static_cast<Property>(I));
      Separator = ", ";
    }
  }
  
  //===----------------------------------------------------------------------===//
  // MachineFunction implementation
  //===----------------------------------------------------------------------===//
  
  // Out-of-line virtual method.
  MachineFunctionInfo::~MachineFunctionInfo() = default;
  
  void ilist_alloc_traits<MachineBasicBlock>::deleteNode(MachineBasicBlock *MBB) {
    MBB->getParent()->DeleteMachineBasicBlock(MBB);
  }
  
  static inline unsigned getFnStackAlignment(const TargetSubtargetInfo *STI,
                                             const Function &F) {
    if (F.hasFnAttribute(Attribute::StackAlignment))
      return F.getFnStackAlignment();
    return STI->getFrameLowering()->getStackAlign().value();
  }
  
  MachineFunction::MachineFunction(Function &F, const LLVMTargetMachine &Target,
                                   const TargetSubtargetInfo &STI,
                                   unsigned FunctionNum, MachineModuleInfo &mmi)
      : F(F), Target(Target), STI(&STI), Ctx(mmi.getContext()), MMI(mmi) {
    FunctionNumber = FunctionNum;
    init();
  }
  
  void MachineFunction::handleInsertion(MachineInstr &MI) {
    if (TheDelegate)
      TheDelegate->MF_HandleInsertion(MI);
  }
  
  void MachineFunction::handleRemoval(MachineInstr &MI) {
    if (TheDelegate)
      TheDelegate->MF_HandleRemoval(MI);
  }
  
  void MachineFunction::init() {
    // Assume the function starts in SSA form with correct liveness.
    Properties.set(MachineFunctionProperties::Property::IsSSA);
    Properties.set(MachineFunctionProperties::Property::TracksLiveness);
    if (STI->getRegisterInfo())
      RegInfo = new (Allocator) MachineRegisterInfo(this);
    else
      RegInfo = nullptr;
  
    MFInfo = nullptr;
    // We can realign the stack if the target supports it and the user hasn't
    // explicitly asked us not to.
    bool CanRealignSP = STI->getFrameLowering()->isStackRealignable() &&
                        !F.hasFnAttribute("no-realign-stack");
    FrameInfo = new (Allocator) MachineFrameInfo(
        getFnStackAlignment(STI, F), /*StackRealignable=*/CanRealignSP,
        /*ForcedRealign=*/CanRealignSP &&
            F.hasFnAttribute(Attribute::StackAlignment));
  
    if (F.hasFnAttribute(Attribute::StackAlignment))
      FrameInfo->ensureMaxAlignment(*F.getFnStackAlign());
  
    ConstantPool = new (Allocator) MachineConstantPool(getDataLayout());
    Alignment = STI->getTargetLowering()->getMinFunctionAlignment();
  
    // FIXME: Shouldn't use pref alignment if explicit alignment is set on F.
    // FIXME: Use Function::hasOptSize().
    if (!F.hasFnAttribute(Attribute::OptimizeForSize))
      Alignment = std::max(Alignment,
                           STI->getTargetLowering()->getPrefFunctionAlignment());
  
    if (AlignAllFunctions)
      Alignment = Align(1ULL << AlignAllFunctions);
  
    JumpTableInfo = nullptr;
  
    if (isFuncletEHPersonality(classifyEHPersonality(
            F.hasPersonalityFn() ? F.getPersonalityFn() : nullptr))) {
      WinEHInfo = new (Allocator) WinEHFuncInfo();
    }
  
    if (isScopedEHPersonality(classifyEHPersonality(
            F.hasPersonalityFn() ? F.getPersonalityFn() : nullptr))) {
      WasmEHInfo = new (Allocator) WasmEHFuncInfo();
    }
  
    assert(Target.isCompatibleDataLayout(getDataLayout()) &&
           "Can't create a MachineFunction using a Module with a "
           "Target-incompatible DataLayout attached\n");
  
    PSVManager =
      std::make_unique<PseudoSourceValueManager>(*(getSubtarget().
                                                    getInstrInfo()));
  }
  
  MachineFunction::~MachineFunction() {
    clear();
  }
  
  void MachineFunction::clear() {
    Properties.reset();
    // Don't call destructors on MachineInstr and MachineOperand. All of their
    // memory comes from the BumpPtrAllocator which is about to be purged.
    //
    // Do call MachineBasicBlock destructors, it contains std::vectors.
    for (iterator I = begin(), E = end(); I != E; I = BasicBlocks.erase(I))
      I->Insts.clearAndLeakNodesUnsafely();
    MBBNumbering.clear();
  
    InstructionRecycler.clear(Allocator);
    OperandRecycler.clear(Allocator);
    BasicBlockRecycler.clear(Allocator);
    CodeViewAnnotations.clear();
    VariableDbgInfos.clear();
    if (RegInfo) {
      RegInfo->~MachineRegisterInfo();
      Allocator.Deallocate(RegInfo);
    }
    if (MFInfo) {
      MFInfo->~MachineFunctionInfo();
      Allocator.Deallocate(MFInfo);
    }
  
    FrameInfo->~MachineFrameInfo();
    Allocator.Deallocate(FrameInfo);
  
    ConstantPool->~MachineConstantPool();
    Allocator.Deallocate(ConstantPool);
  
    if (JumpTableInfo) {
      JumpTableInfo->~MachineJumpTableInfo();
      Allocator.Deallocate(JumpTableInfo);
    }
  
    if (WinEHInfo) {
      WinEHInfo->~WinEHFuncInfo();
      Allocator.Deallocate(WinEHInfo);
    }
  
    if (WasmEHInfo) {
      WasmEHInfo->~WasmEHFuncInfo();
      Allocator.Deallocate(WasmEHInfo);
    }
  }
  
  const DataLayout &MachineFunction::getDataLayout() const {
    return F.getParent()->getDataLayout();
  }
  
  /// Get the JumpTableInfo for this function.
  /// If it does not already exist, allocate one.
  MachineJumpTableInfo *MachineFunction::
  getOrCreateJumpTableInfo(unsigned EntryKind) {
    if (JumpTableInfo) return JumpTableInfo;
  
    JumpTableInfo = new (Allocator)
      MachineJumpTableInfo((MachineJumpTableInfo::JTEntryKind)EntryKind);
    return JumpTableInfo;
  }
  
  DenormalMode MachineFunction::getDenormalMode(const fltSemantics &FPType) const {
    return F.getDenormalMode(FPType);
  }
  
  /// Should we be emitting segmented stack stuff for the function
  bool MachineFunction::shouldSplitStack() const {
    return getFunction().hasFnAttribute("split-stack");
  }
  
  LLVM_NODISCARD unsigned
  MachineFunction::addFrameInst(const MCCFIInstruction &Inst) {
    FrameInstructions.push_back(Inst);
    return FrameInstructions.size() - 1;
  }
  
  /// This discards all of the MachineBasicBlock numbers and recomputes them.
  /// This guarantees that the MBB numbers are sequential, dense, and match the
  /// ordering of the blocks within the function.  If a specific MachineBasicBlock
  /// is specified, only that block and those after it are renumbered.
  void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
    if (empty()) { MBBNumbering.clear(); return; }
    MachineFunction::iterator MBBI, E = end();
    if (MBB == nullptr)
      MBBI = begin();
    else
      MBBI = MBB->getIterator();
  
    // Figure out the block number this should have.
    unsigned BlockNo = 0;
    if (MBBI != begin())
      BlockNo = std::prev(MBBI)->getNumber() + 1;
  
    for (; MBBI != E; ++MBBI, ++BlockNo) {
      if (MBBI->getNumber() != (int)BlockNo) {
        // Remove use of the old number.
        if (MBBI->getNumber() != -1) {
          assert(MBBNumbering[MBBI->getNumber()] == &*MBBI &&
                 "MBB number mismatch!");
          MBBNumbering[MBBI->getNumber()] = nullptr;
        }
  
        // If BlockNo is already taken, set that block's number to -1.
        if (MBBNumbering[BlockNo])
          MBBNumbering[BlockNo]->setNumber(-1);
  
        MBBNumbering[BlockNo] = &*MBBI;
        MBBI->setNumber(BlockNo);
      }
    }
  
    // Okay, all the blocks are renumbered.  If we have compactified the block
    // numbering, shrink MBBNumbering now.
    assert(BlockNo <= MBBNumbering.size() && "Mismatch!");
    MBBNumbering.resize(BlockNo);
  }
  
  /// This method iterates over the basic blocks and assigns their IsBeginSection
  /// and IsEndSection fields. This must be called after MBB layout is finalized
  /// and the SectionID's are assigned to MBBs.
  void MachineFunction::assignBeginEndSections() {
    front().setIsBeginSection();
    auto CurrentSectionID = front().getSectionID();
    for (auto MBBI = std::next(begin()), E = end(); MBBI != E; ++MBBI) {
      if (MBBI->getSectionID() == CurrentSectionID)
        continue;
      MBBI->setIsBeginSection();
      std::prev(MBBI)->setIsEndSection();
      CurrentSectionID = MBBI->getSectionID();
    }
    back().setIsEndSection();
  }
  
  /// Allocate a new MachineInstr. Use this instead of `new MachineInstr'.
  MachineInstr *MachineFunction::CreateMachineInstr(const MCInstrDesc &MCID,
                                                    const DebugLoc &DL,
                                                    bool NoImplicit) {
    return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
        MachineInstr(*this, MCID, DL, NoImplicit);
  }
  
  /// Create a new MachineInstr which is a copy of the 'Orig' instruction,
  /// identical in all ways except the instruction has no parent, prev, or next.
  MachineInstr *
  MachineFunction::CloneMachineInstr(const MachineInstr *Orig) {
    return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
               MachineInstr(*this, *Orig);
  }
  
  MachineInstr &MachineFunction::CloneMachineInstrBundle(MachineBasicBlock &MBB,
      MachineBasicBlock::iterator InsertBefore, const MachineInstr &Orig) {
    MachineInstr *FirstClone = nullptr;
    MachineBasicBlock::const_instr_iterator I = Orig.getIterator();
    while (true) {
      MachineInstr *Cloned = CloneMachineInstr(&*I);
      MBB.insert(InsertBefore, Cloned);
      if (FirstClone == nullptr) {
        FirstClone = Cloned;
      } else {
        Cloned->bundleWithPred();
      }
  
      if (!I->isBundledWithSucc())
        break;
      ++I;
    }
    // Copy over call site info to the cloned instruction if needed. If Orig is in
    // a bundle, copyCallSiteInfo takes care of finding the call instruction in
    // the bundle.
    if (Orig.shouldUpdateCallSiteInfo())
      copyCallSiteInfo(&Orig, FirstClone);
    return *FirstClone;
  }
  
  /// Delete the given MachineInstr.
  ///
  /// This function also serves as the MachineInstr destructor - the real
  /// ~MachineInstr() destructor must be empty.
  void
  MachineFunction::DeleteMachineInstr(MachineInstr *MI) {
    // Verify that a call site info is at valid state. This assertion should
    // be triggered during the implementation of support for the
    // call site info of a new architecture. If the assertion is triggered,
    // back trace will tell where to insert a call to updateCallSiteInfo().
    assert((!MI->isCandidateForCallSiteEntry() ||
            CallSitesInfo.find(MI) == CallSitesInfo.end()) &&
           "Call site info was not updated!");
    // Strip it for parts. The operand array and the MI object itself are
    // independently recyclable.
    if (MI->Operands)
      deallocateOperandArray(MI->CapOperands, MI->Operands);
    // Don't call ~MachineInstr() which must be trivial anyway because
    // ~MachineFunction drops whole lists of MachineInstrs wihout calling their
    // destructors.
    InstructionRecycler.Deallocate(Allocator, MI);
  }
  
  /// Allocate a new MachineBasicBlock. Use this instead of
  /// `new MachineBasicBlock'.
  MachineBasicBlock *
  MachineFunction::CreateMachineBasicBlock(const BasicBlock *bb) {
    return new (BasicBlockRecycler.Allocate<MachineBasicBlock>(Allocator))
               MachineBasicBlock(*this, bb);
  }
  
  /// Delete the given MachineBasicBlock.
  void
  MachineFunction::DeleteMachineBasicBlock(MachineBasicBlock *MBB) {
    assert(MBB->getParent() == this && "MBB parent mismatch!");
    // Clean up any references to MBB in jump tables before deleting it.
    if (JumpTableInfo)
      JumpTableInfo->RemoveMBBFromJumpTables(MBB);
    MBB->~MachineBasicBlock();
    BasicBlockRecycler.Deallocate(Allocator, MBB);
  }
  
  MachineMemOperand *MachineFunction::getMachineMemOperand(
      MachinePointerInfo PtrInfo, MachineMemOperand::Flags f, uint64_t s,
      Align base_alignment, const AAMDNodes &AAInfo, const MDNode *Ranges,
      SyncScope::ID SSID, AtomicOrdering Ordering,
      AtomicOrdering FailureOrdering) {
    return new (Allocator)
        MachineMemOperand(PtrInfo, f, s, base_alignment, AAInfo, Ranges,
                          SSID, Ordering, FailureOrdering);
  }
  
  MachineMemOperand *MachineFunction::getMachineMemOperand(
      MachinePointerInfo PtrInfo, MachineMemOperand::Flags f, LLT MemTy,
      Align base_alignment, const AAMDNodes &AAInfo, const MDNode *Ranges,
      SyncScope::ID SSID, AtomicOrdering Ordering,
      AtomicOrdering FailureOrdering) {
    return new (Allocator)
        MachineMemOperand(PtrInfo, f, MemTy, base_alignment, AAInfo, Ranges, SSID,
                          Ordering, FailureOrdering);
  }
  
  MachineMemOperand *MachineFunction::getMachineMemOperand(
      const MachineMemOperand *MMO, const MachinePointerInfo &PtrInfo, uint64_t Size) {
    return new (Allocator)
        MachineMemOperand(PtrInfo, MMO->getFlags(), Size, MMO->getBaseAlign(),
                          AAMDNodes(), nullptr, MMO->getSyncScopeID(),
                          MMO->getSuccessOrdering(), MMO->getFailureOrdering());
  }
  
  MachineMemOperand *MachineFunction::getMachineMemOperand(
      const MachineMemOperand *MMO, const MachinePointerInfo &PtrInfo, LLT Ty) {
    return new (Allocator)
        MachineMemOperand(PtrInfo, MMO->getFlags(), Ty, MMO->getBaseAlign(),
                          AAMDNodes(), nullptr, MMO->getSyncScopeID(),
                          MMO->getSuccessOrdering(), MMO->getFailureOrdering());
  }
  
  MachineMemOperand *
  MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
                                        int64_t Offset, LLT Ty) {
    const MachinePointerInfo &PtrInfo = MMO->getPointerInfo();
  
    // If there is no pointer value, the offset isn't tracked so we need to adjust
    // the base alignment.
    Align Alignment = PtrInfo.V.isNull()
                          ? commonAlignment(MMO->getBaseAlign(), Offset)
                          : MMO->getBaseAlign();
  
    // Do not preserve ranges, since we don't necessarily know what the high bits
    // are anymore.
    return new (Allocator) MachineMemOperand(
        PtrInfo.getWithOffset(Offset), MMO->getFlags(), Ty, Alignment,
        MMO->getAAInfo(), nullptr, MMO->getSyncScopeID(),
        MMO->getSuccessOrdering(), MMO->getFailureOrdering());
  }
  
  MachineMemOperand *
  MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
                                        const AAMDNodes &AAInfo) {
    MachinePointerInfo MPI = MMO->getValue() ?
               MachinePointerInfo(MMO->getValue(), MMO->getOffset()) :
               MachinePointerInfo(MMO->getPseudoValue(), MMO->getOffset());
  
    return new (Allocator) MachineMemOperand(
        MPI, MMO->getFlags(), MMO->getSize(), MMO->getBaseAlign(), AAInfo,
        MMO->getRanges(), MMO->getSyncScopeID(), MMO->getSuccessOrdering(),
        MMO->getFailureOrdering());
  }
  
  MachineMemOperand *
  MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
                                        MachineMemOperand::Flags Flags) {
    return new (Allocator) MachineMemOperand(
        MMO->getPointerInfo(), Flags, MMO->getSize(), MMO->getBaseAlign(),
        MMO->getAAInfo(), MMO->getRanges(), MMO->getSyncScopeID(),
        MMO->getSuccessOrdering(), MMO->getFailureOrdering());
  }
  
  MachineInstr::ExtraInfo *MachineFunction::createMIExtraInfo(
      ArrayRef<MachineMemOperand *> MMOs, MCSymbol *PreInstrSymbol,
      MCSymbol *PostInstrSymbol, MDNode *HeapAllocMarker) {
    return MachineInstr::ExtraInfo::create(Allocator, MMOs, PreInstrSymbol,
                                           PostInstrSymbol, HeapAllocMarker);
  }
  
  const char *MachineFunction::createExternalSymbolName(StringRef Name) {
    char *Dest = Allocator.Allocate<char>(Name.size() + 1);
    llvm::copy(Name, Dest);
    Dest[Name.size()] = 0;
    return Dest;
  }
  
  uint32_t *MachineFunction::allocateRegMask() {
    unsigned NumRegs = getSubtarget().getRegisterInfo()->getNumRegs();
    unsigned Size = MachineOperand::getRegMaskSize(NumRegs);
    uint32_t *Mask = Allocator.Allocate<uint32_t>(Size);
    memset(Mask, 0, Size * sizeof(Mask[0]));
    return Mask;
  }
  
  ArrayRef<int> MachineFunction::allocateShuffleMask(ArrayRef<int> Mask) {
    int* AllocMask = Allocator.Allocate<int>(Mask.size());
    copy(Mask, AllocMask);
    return {AllocMask, Mask.size()};
  }
  
  #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void MachineFunction::dump() const {
    print(dbgs());
  }
  #endif
  
  StringRef MachineFunction::getName() const {
    return getFunction().getName();
  }
  
  void MachineFunction::print(raw_ostream &OS, const SlotIndexes *Indexes) const {
    OS << "# Machine code for function " << getName() << ": ";
    getProperties().print(OS);
    OS << '\n';
  
    // Print Frame Information
    FrameInfo->print(*this, OS);
  
    // Print JumpTable Information
    if (JumpTableInfo)
      JumpTableInfo->print(OS);
  
    // Print Constant Pool
    ConstantPool->print(OS);
  
    const TargetRegisterInfo *TRI = getSubtarget().getRegisterInfo();
  
    if (RegInfo && !RegInfo->livein_empty()) {
      OS << "Function Live Ins: ";
      for (MachineRegisterInfo::livein_iterator
           I = RegInfo->livein_begin(), E = RegInfo->livein_end(); I != E; ++I) {
        OS << printReg(I->first, TRI);
        if (I->second)
          OS << " in " << printReg(I->second, TRI);
        if (std::next(I) != E)
          OS << ", ";
      }
      OS << '\n';
    }
  
    ModuleSlotTracker MST(getFunction().getParent());
    MST.incorporateFunction(getFunction());
    for (const auto &BB : *this) {
      OS << '\n';
      // If we print the whole function, print it at its most verbose level.
      BB.print(OS, MST, Indexes, /*IsStandalone=*/true);
    }
  
    OS << "\n# End machine code for function " << getName() << ".\n\n";
  }
  
  /// True if this function needs frame moves for debug or exceptions.
  bool MachineFunction::needsFrameMoves() const {
    return getMMI().hasDebugInfo() ||
           getTarget().Options.ForceDwarfFrameSection ||
           F.needsUnwindTableEntry();
  }
  
  namespace llvm {
  
    template<>
    struct DOTGraphTraits<const MachineFunction*> : public DefaultDOTGraphTraits {
      DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
  
      static std::string getGraphName(const MachineFunction *F) {
        return ("CFG for '" + F->getName() + "' function").str();
      }
  
      std::string getNodeLabel(const MachineBasicBlock *Node,
                               const MachineFunction *Graph) {
        std::string OutStr;
        {
          raw_string_ostream OSS(OutStr);
  
          if (isSimple()) {
            OSS << printMBBReference(*Node);
            if (const BasicBlock *BB = Node->getBasicBlock())
              OSS << ": " << BB->getName();
          } else
            Node->print(OSS);
        }
  
        if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
  
        // Process string output to make it nicer...
        for (unsigned i = 0; i != OutStr.length(); ++i)
          if (OutStr[i] == '\n') {                            // Left justify
            OutStr[i] = '\\';
            OutStr.insert(OutStr.begin()+i+1, 'l');
          }
        return OutStr;
      }
    };
  
  } // end namespace llvm
  
  void MachineFunction::viewCFG() const
  {
  #ifndef NDEBUG
    ViewGraph(this, "mf" + getName());
  #else
    errs() << "MachineFunction::viewCFG is only available in debug builds on "
           << "systems with Graphviz or gv!\n";
  #endif // NDEBUG
  }
  
  void MachineFunction::viewCFGOnly() const
  {
  #ifndef NDEBUG
    ViewGraph(this, "mf" + getName(), true);
  #else
    errs() << "MachineFunction::viewCFGOnly is only available in debug builds on "
           << "systems with Graphviz or gv!\n";
  #endif // NDEBUG
  }
  
  /// Add the specified physical register as a live-in value and
  /// create a corresponding virtual register for it.
  Register MachineFunction::addLiveIn(MCRegister PReg,
                                      const TargetRegisterClass *RC) {
    MachineRegisterInfo &MRI = getRegInfo();
    Register VReg = MRI.getLiveInVirtReg(PReg);
    if (VReg) {
      const TargetRegisterClass *VRegRC = MRI.getRegClass(VReg);
      (void)VRegRC;
      // A physical register can be added several times.
      // Between two calls, the register class of the related virtual register
      // may have been constrained to match some operation constraints.
      // In that case, check that the current register class includes the
      // physical register and is a sub class of the specified RC.
      assert((VRegRC == RC || (VRegRC->contains(PReg) &&
                               RC->hasSubClassEq(VRegRC))) &&
              "Register class mismatch!");
      return VReg;
    }
    VReg = MRI.createVirtualRegister(RC);
    MRI.addLiveIn(PReg, VReg);
    return VReg;
  }
  
  /// Return the MCSymbol for the specified non-empty jump table.
  /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
  /// normal 'L' label is returned.
  MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
                                          bool isLinkerPrivate) const {
    const DataLayout &DL = getDataLayout();
    assert(JumpTableInfo && "No jump tables");
    assert(JTI < JumpTableInfo->getJumpTables().size() && "Invalid JTI!");
  
    StringRef Prefix = isLinkerPrivate ? DL.getLinkerPrivateGlobalPrefix()
                                       : DL.getPrivateGlobalPrefix();
    SmallString<60> Name;
    raw_svector_ostream(Name)
      << Prefix << "JTI" << getFunctionNumber() << '_' << JTI;
    return Ctx.getOrCreateSymbol(Name);
  }
  
  /// Return a function-local symbol to represent the PIC base.
  MCSymbol *MachineFunction::getPICBaseSymbol() const {
    const DataLayout &DL = getDataLayout();
    return Ctx.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
                                 Twine(getFunctionNumber()) + "$pb");
  }
  
  /// \name Exception Handling
  /// \{
  
  LandingPadInfo &
  MachineFunction::getOrCreateLandingPadInfo(MachineBasicBlock *LandingPad) {
    unsigned N = LandingPads.size();
    for (unsigned i = 0; i < N; ++i) {
      LandingPadInfo &LP = LandingPads[i];
      if (LP.LandingPadBlock == LandingPad)
        return LP;
    }
  
    LandingPads.push_back(LandingPadInfo(LandingPad));
    return LandingPads[N];
  }
  
  void MachineFunction::addInvoke(MachineBasicBlock *LandingPad,
                                  MCSymbol *BeginLabel, MCSymbol *EndLabel) {
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    LP.BeginLabels.push_back(BeginLabel);
    LP.EndLabels.push_back(EndLabel);
  }
  
  MCSymbol *MachineFunction::addLandingPad(MachineBasicBlock *LandingPad) {
    MCSymbol *LandingPadLabel = Ctx.createTempSymbol();
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    LP.LandingPadLabel = LandingPadLabel;
  
    const Instruction *FirstI = LandingPad->getBasicBlock()->getFirstNonPHI();
    if (const auto *LPI = dyn_cast<LandingPadInst>(FirstI)) {
      if (const auto *PF =
              dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts()))
        getMMI().addPersonality(PF);
  
      if (LPI->isCleanup())
        addCleanup(LandingPad);
  
      // FIXME: New EH - Add the clauses in reverse order. This isn't 100%
      //        correct, but we need to do it this way because of how the DWARF EH
      //        emitter processes the clauses.
      for (unsigned I = LPI->getNumClauses(); I != 0; --I) {
        Value *Val = LPI->getClause(I - 1);
        if (LPI->isCatch(I - 1)) {
          addCatchTypeInfo(LandingPad,
                           dyn_cast<GlobalValue>(Val->stripPointerCasts()));
        } else {
          // Add filters in a list.
          auto *CVal = cast<Constant>(Val);
          SmallVector<const GlobalValue *, 4> FilterList;
          for (User::op_iterator II = CVal->op_begin(), IE = CVal->op_end();
               II != IE; ++II)
            FilterList.push_back(cast<GlobalValue>((*II)->stripPointerCasts()));
  
          addFilterTypeInfo(LandingPad, FilterList);
        }
      }
  
    } else if (const auto *CPI = dyn_cast<CatchPadInst>(FirstI)) {
      for (unsigned I = CPI->getNumArgOperands(); I != 0; --I) {
        Value *TypeInfo = CPI->getArgOperand(I - 1)->stripPointerCasts();
        addCatchTypeInfo(LandingPad, dyn_cast<GlobalValue>(TypeInfo));
      }
  
    } else {
      assert(isa<CleanupPadInst>(FirstI) && "Invalid landingpad!");
    }
  
    return LandingPadLabel;
  }
  
  void MachineFunction::addCatchTypeInfo(MachineBasicBlock *LandingPad,
                                         ArrayRef<const GlobalValue *> TyInfo) {
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    for (unsigned N = TyInfo.size(); N; --N)
      LP.TypeIds.push_back(getTypeIDFor(TyInfo[N - 1]));
  }
  
  void MachineFunction::addFilterTypeInfo(MachineBasicBlock *LandingPad,
                                          ArrayRef<const GlobalValue *> TyInfo) {
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    std::vector<unsigned> IdsInFilter(TyInfo.size());
    for (unsigned I = 0, E = TyInfo.size(); I != E; ++I)
      IdsInFilter[I] = getTypeIDFor(TyInfo[I]);
    LP.TypeIds.push_back(getFilterIDFor(IdsInFilter));
  }
  
  void MachineFunction::tidyLandingPads(DenseMap<MCSymbol *, uintptr_t> *LPMap,
                                        bool TidyIfNoBeginLabels) {
    for (unsigned i = 0; i != LandingPads.size(); ) {
      LandingPadInfo &LandingPad = LandingPads[i];
      if (LandingPad.LandingPadLabel &&
          !LandingPad.LandingPadLabel->isDefined() &&
          (!LPMap || (*LPMap)[LandingPad.LandingPadLabel] == 0))
        LandingPad.LandingPadLabel = nullptr;
  
      // Special case: we *should* emit LPs with null LP MBB. This indicates
      // "nounwind" case.
      if (!LandingPad.LandingPadLabel && LandingPad.LandingPadBlock) {
        LandingPads.erase(LandingPads.begin() + i);
        continue;
      }
  
      if (TidyIfNoBeginLabels) {
        for (unsigned j = 0, e = LandingPads[i].BeginLabels.size(); j != e; ++j) {
          MCSymbol *BeginLabel = LandingPad.BeginLabels[j];
          MCSymbol *EndLabel = LandingPad.EndLabels[j];
          if ((BeginLabel->isDefined() || (LPMap && (*LPMap)[BeginLabel] != 0)) &&
              (EndLabel->isDefined() || (LPMap && (*LPMap)[EndLabel] != 0)))
            continue;
  
          LandingPad.BeginLabels.erase(LandingPad.BeginLabels.begin() + j);
          LandingPad.EndLabels.erase(LandingPad.EndLabels.begin() + j);
          --j;
          --e;
        }
  
        // Remove landing pads with no try-ranges.
        if (LandingPads[i].BeginLabels.empty()) {
          LandingPads.erase(LandingPads.begin() + i);
          continue;
        }
      }
  
      // If there is no landing pad, ensure that the list of typeids is empty.
      // If the only typeid is a cleanup, this is the same as having no typeids.
      if (!LandingPad.LandingPadBlock ||
          (LandingPad.TypeIds.size() == 1 && !LandingPad.TypeIds[0]))
        LandingPad.TypeIds.clear();
      ++i;
    }
  }
  
  void MachineFunction::addCleanup(MachineBasicBlock *LandingPad) {
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    LP.TypeIds.push_back(0);
  }
  
  void MachineFunction::addSEHCatchHandler(MachineBasicBlock *LandingPad,
                                           const Function *Filter,
                                           const BlockAddress *RecoverBA) {
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    SEHHandler Handler;
    Handler.FilterOrFinally = Filter;
    Handler.RecoverBA = RecoverBA;
    LP.SEHHandlers.push_back(Handler);
  }
  
  void MachineFunction::addSEHCleanupHandler(MachineBasicBlock *LandingPad,
                                             const Function *Cleanup) {
    LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
    SEHHandler Handler;
    Handler.FilterOrFinally = Cleanup;
    Handler.RecoverBA = nullptr;
    LP.SEHHandlers.push_back(Handler);
  }
  
  void MachineFunction::setCallSiteLandingPad(MCSymbol *Sym,
                                              ArrayRef<unsigned> Sites) {
    LPadToCallSiteMap[Sym].append(Sites.begin(), Sites.end());
  }
  
  unsigned MachineFunction::getTypeIDFor(const GlobalValue *TI) {
    for (unsigned i = 0, N = TypeInfos.size(); i != N; ++i)
      if (TypeInfos[i] == TI) return i + 1;
  
    TypeInfos.push_back(TI);
    return TypeInfos.size();
  }
  
  int MachineFunction::getFilterIDFor(std::vector<unsigned> &TyIds) {
    // If the new filter coincides with the tail of an existing filter, then
    // re-use the existing filter.  Folding filters more than this requires
    // re-ordering filters and/or their elements - probably not worth it.
    for (unsigned i : FilterEnds) {
      unsigned j = TyIds.size();
  
      while (i && j)
        if (FilterIds[--i] != TyIds[--j])
          goto try_next;
  
      if (!j)
        // The new filter coincides with range [i, end) of the existing filter.
        return -(1 + i);
  
  try_next:;
    }
  
    // Add the new filter.
    int FilterID = -(1 + FilterIds.size());
    FilterIds.reserve(FilterIds.size() + TyIds.size() + 1);
    llvm::append_range(FilterIds, TyIds);
    FilterEnds.push_back(FilterIds.size());
    FilterIds.push_back(0); // terminator
    return FilterID;
  }
  
  MachineFunction::CallSiteInfoMap::iterator
  MachineFunction::getCallSiteInfo(const MachineInstr *MI) {
    assert(MI->isCandidateForCallSiteEntry() &&
           "Call site info refers only to call (MI) candidates");
  
    if (!Target.Options.EmitCallSiteInfo)
      return CallSitesInfo.end();
    return CallSitesInfo.find(MI);
  }
  
  /// Return the call machine instruction or find a call within bundle.
  static const MachineInstr *getCallInstr(const MachineInstr *MI) {
    if (!MI->isBundle())
      return MI;
  
    for (auto &BMI : make_range(getBundleStart(MI->getIterator()),
                                getBundleEnd(MI->getIterator())))
      if (BMI.isCandidateForCallSiteEntry())
        return &BMI;
  
    llvm_unreachable("Unexpected bundle without a call site candidate");
  }
  
  void MachineFunction::eraseCallSiteInfo(const MachineInstr *MI) {
    assert(MI->shouldUpdateCallSiteInfo() &&
           "Call site info refers only to call (MI) candidates or "
           "candidates inside bundles");
  
    const MachineInstr *CallMI = getCallInstr(MI);
    CallSiteInfoMap::iterator CSIt = getCallSiteInfo(CallMI);
    if (CSIt == CallSitesInfo.end())
      return;
    CallSitesInfo.erase(CSIt);
  }
  
  void MachineFunction::copyCallSiteInfo(const MachineInstr *Old,
                                         const MachineInstr *New) {
    assert(Old->shouldUpdateCallSiteInfo() &&
           "Call site info refers only to call (MI) candidates or "
           "candidates inside bundles");
  
    if (!New->isCandidateForCallSiteEntry())
      return eraseCallSiteInfo(Old);
  
    const MachineInstr *OldCallMI = getCallInstr(Old);
    CallSiteInfoMap::iterator CSIt = getCallSiteInfo(OldCallMI);
    if (CSIt == CallSitesInfo.end())
      return;
  
    CallSiteInfo CSInfo = CSIt->second;
    CallSitesInfo[New] = CSInfo;
  }
  
  void MachineFunction::moveCallSiteInfo(const MachineInstr *Old,
                                         const MachineInstr *New) {
    assert(Old->shouldUpdateCallSiteInfo() &&
           "Call site info refers only to call (MI) candidates or "
           "candidates inside bundles");
  
    if (!New->isCandidateForCallSiteEntry())
      return eraseCallSiteInfo(Old);
  
    const MachineInstr *OldCallMI = getCallInstr(Old);
    CallSiteInfoMap::iterator CSIt = getCallSiteInfo(OldCallMI);
    if (CSIt == CallSitesInfo.end())
      return;
  
    CallSiteInfo CSInfo = std::move(CSIt->second);
    CallSitesInfo.erase(CSIt);
    CallSitesInfo[New] = CSInfo;
  }
  
  void MachineFunction::setDebugInstrNumberingCount(unsigned Num) {
    DebugInstrNumberingCount = Num;
  }
  
  void MachineFunction::makeDebugValueSubstitution(DebugInstrOperandPair A,
                                                   DebugInstrOperandPair B,
                                                   unsigned Subreg) {
    // Catch any accidental self-loops.
    assert(A.first != B.first);
    DebugValueSubstitutions.push_back({A, B, Subreg});
  }
  
  void MachineFunction::substituteDebugValuesForInst(const MachineInstr &Old,
                                                     MachineInstr &New,
                                                     unsigned MaxOperand) {
    // If the Old instruction wasn't tracked at all, there is no work to do.
    unsigned OldInstrNum = Old.peekDebugInstrNum();
    if (!OldInstrNum)
      return;
  
    // Iterate over all operands looking for defs to create substitutions for.
    // Avoid creating new instr numbers unless we create a new substitution.
    // While this has no functional effect, it risks confusing someone reading
    // MIR output.
    // Examine all the operands, or the first N specified by the caller.
    MaxOperand = std::min(MaxOperand, Old.getNumOperands());
    for (unsigned int I = 0; I < Old.getNumOperands(); ++I) {
      const auto &OldMO = Old.getOperand(I);
      auto &NewMO = New.getOperand(I);
      (void)NewMO;
  
      if (!OldMO.isReg() || !OldMO.isDef())
        continue;
      assert(NewMO.isDef());
  
      unsigned NewInstrNum = New.getDebugInstrNum();
      makeDebugValueSubstitution(std::make_pair(OldInstrNum, I),
                                 std::make_pair(NewInstrNum, I));
    }
  }
  
  auto MachineFunction::salvageCopySSA(MachineInstr &MI)
      -> DebugInstrOperandPair {
    MachineRegisterInfo &MRI = getRegInfo();
    const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
    const TargetInstrInfo &TII = *getSubtarget().getInstrInfo();
  
    // Chase the value read by a copy-like instruction back to the instruction
    // that ultimately _defines_ that value. This may pass:
    //  * Through multiple intermediate copies, including subregister moves /
    //    copies,
    //  * Copies from physical registers that must then be traced back to the
    //    defining instruction,
    //  * Or, physical registers may be live-in to (only) the entry block, which
    //    requires a DBG_PHI to be created.
    // We can pursue this problem in that order: trace back through copies,
    // optionally through a physical register, to a defining instruction. We
    // should never move from physreg to vreg. As we're still in SSA form, no need
    // to worry about partial definitions of registers.
  
    // Helper lambda to interpret a copy-like instruction. Takes instruction,
    // returns the register read and any subregister identifying which part is
    // read.
    auto GetRegAndSubreg =
        [&](const MachineInstr &Cpy) -> std::pair<Register, unsigned> {
      Register NewReg, OldReg;
      unsigned SubReg;
      if (Cpy.isCopy()) {
        OldReg = Cpy.getOperand(0).getReg();
        NewReg = Cpy.getOperand(1).getReg();
        SubReg = Cpy.getOperand(1).getSubReg();
      } else if (Cpy.isSubregToReg()) {
        OldReg = Cpy.getOperand(0).getReg();
        NewReg = Cpy.getOperand(2).getReg();
        SubReg = Cpy.getOperand(3).getImm();
      } else {
        auto CopyDetails = *TII.isCopyInstr(Cpy);
        const MachineOperand &Src = *CopyDetails.Source;
        const MachineOperand &Dest = *CopyDetails.Destination;
        OldReg = Dest.getReg();
        NewReg = Src.getReg();
        SubReg = Src.getSubReg();
      }
  
      return {NewReg, SubReg};
    };
  
    // First seek either the defining instruction, or a copy from a physreg.
    // During search, the current state is the current copy instruction, and which
    // register we've read. Accumulate qualifying subregisters into SubregsSeen;
    // deal with those later.
    auto State = GetRegAndSubreg(MI);
    auto CurInst = MI.getIterator();
    SmallVector<unsigned, 4> SubregsSeen;
    while (true) {
      // If we've found a copy from a physreg, first portion of search is over.
      if (!State.first.isVirtual())
        break;
  
      // Record any subregister qualifier.
      if (State.second)
        SubregsSeen.push_back(State.second);
  
      assert(MRI.hasOneDef(State.first));
      MachineInstr &Inst = *MRI.def_begin(State.first)->getParent();
      CurInst = Inst.getIterator();
  
      // Any non-copy instruction is the defining instruction we're seeking.
      if (!Inst.isCopyLike() && !TII.isCopyInstr(Inst))
        break;
      State = GetRegAndSubreg(Inst);
    };
  
    // Helper lambda to apply additional subregister substitutions to a known
    // instruction/operand pair. Adds new (fake) substitutions so that we can
    // record the subregister. FIXME: this isn't very space efficient if multiple
    // values are tracked back through the same copies; cache something later.
    auto ApplySubregisters =
        [&](DebugInstrOperandPair P) -> DebugInstrOperandPair {
      for (unsigned Subreg : reverse(SubregsSeen)) {
        // Fetch a new instruction number, not attached to an actual instruction.
        unsigned NewInstrNumber = getNewDebugInstrNum();
        // Add a substitution from the "new" number to the known one, with a
        // qualifying subreg.
        makeDebugValueSubstitution({NewInstrNumber, 0}, P, Subreg);
        // Return the new number; to find the underlying value, consumers need to
        // deal with the qualifying subreg.
        P = {NewInstrNumber, 0};
      }
      return P;
    };
  
    // If we managed to find the defining instruction after COPYs, return an
    // instruction / operand pair after adding subregister qualifiers.
    if (State.first.isVirtual()) {
      // Virtual register def -- we can just look up where this happens.
      MachineInstr *Inst = MRI.def_begin(State.first)->getParent();
      for (auto &MO : Inst->operands()) {
        if (!MO.isReg() || !MO.isDef() || MO.getReg() != State.first)
          continue;
        return ApplySubregisters(
            {Inst->getDebugInstrNum(), Inst->getOperandNo(&MO)});
      }
  
      llvm_unreachable("Vreg def with no corresponding operand?");
    }
  
    // Our search ended in a copy from a physreg: walk back up the function
    // looking for whatever defines the physreg.
    assert(CurInst->isCopyLike() || TII.isCopyInstr(*CurInst));
    State = GetRegAndSubreg(*CurInst);
    Register RegToSeek = State.first;
  
    auto RMII = CurInst->getReverseIterator();
    auto PrevInstrs = make_range(RMII, CurInst->getParent()->instr_rend());
    for (auto &ToExamine : PrevInstrs) {
      for (auto &MO : ToExamine.operands()) {
        // Test for operand that defines something aliasing RegToSeek.
        if (!MO.isReg() || !MO.isDef() ||
            !TRI.regsOverlap(RegToSeek, MO.getReg()))
          continue;
  
        return ApplySubregisters(
            {ToExamine.getDebugInstrNum(), ToExamine.getOperandNo(&MO)});
      }
    }
  
    // We reached the start of the block before finding a defining instruction.
    // It must be an argument: assert that this is the entry block, and produce
    // a DBG_PHI.
    assert(!State.first.isVirtual());
    MachineBasicBlock &TargetBB = *CurInst->getParent();
    assert(&*TargetBB.getParent()->begin() == &TargetBB);
  
    // Create DBG_PHI for specified physreg.
    auto Builder = BuildMI(TargetBB, TargetBB.getFirstNonPHI(), DebugLoc(),
                           TII.get(TargetOpcode::DBG_PHI));
    Builder.addReg(State.first, RegState::Debug);
    unsigned NewNum = getNewDebugInstrNum();
    Builder.addImm(NewNum);
    return ApplySubregisters({NewNum, 0u});
  }
  
  void MachineFunction::finalizeDebugInstrRefs() {
    auto *TII = getSubtarget().getInstrInfo();
  
    auto MakeDbgValue = [&](MachineInstr &MI) {
      const MCInstrDesc &RefII = TII->get(TargetOpcode::DBG_VALUE);
      MI.setDesc(RefII);
      MI.getOperand(1).ChangeToRegister(0, false);
      MI.getOperand(0).setIsDebug();
    };
  
    if (!getTarget().Options.ValueTrackingVariableLocations)
      return;
  
    for (auto &MBB : *this) {
      for (auto &MI : MBB) {
        if (!MI.isDebugRef() || !MI.getOperand(0).isReg())
          continue;
  
        Register Reg = MI.getOperand(0).getReg();
  
        // Some vregs can be deleted as redundant in the meantime. Mark those
        // as DBG_VALUE $noreg.
        if (Reg == 0) {
          MakeDbgValue(MI);
          continue;
        }
  
        assert(Reg.isVirtual());
        MachineInstr &DefMI = *RegInfo->def_instr_begin(Reg);
        assert(RegInfo->hasOneDef(Reg));
  
        // If we've found a copy-like instruction, follow it back to the
        // instruction that defines the source value, see salvageCopySSA docs
        // for why this is important.
        if (DefMI.isCopyLike() || TII->isCopyInstr(DefMI)) {
          auto Result = salvageCopySSA(DefMI);
          MI.getOperand(0).ChangeToImmediate(Result.first);
          MI.getOperand(1).setImm(Result.second);
        } else {
          // Otherwise, identify the operand number that the VReg refers to.
          unsigned OperandIdx = 0;
          for (const auto &MO : DefMI.operands()) {
            if (MO.isReg() && MO.isDef() && MO.getReg() == Reg)
              break;
            ++OperandIdx;
          }
          assert(OperandIdx < DefMI.getNumOperands());
  
          // Morph this instr ref to point at the given instruction and operand.
          unsigned ID = DefMI.getDebugInstrNum();
          MI.getOperand(0).ChangeToImmediate(ID);
          MI.getOperand(1).setImm(OperandIdx);
        }
      }
    }
  }
  
  /// \}
  
  //===----------------------------------------------------------------------===//
  //  MachineJumpTableInfo implementation
  //===----------------------------------------------------------------------===//
  
  /// Return the size of each entry in the jump table.
  unsigned MachineJumpTableInfo::getEntrySize(const DataLayout &TD) const {
    // The size of a jump table entry is 4 bytes unless the entry is just the
    // address of a block, in which case it is the pointer size.
    switch (getEntryKind()) {
    case MachineJumpTableInfo::EK_BlockAddress:
      return TD.getPointerSize();
    case MachineJumpTableInfo::EK_GPRel64BlockAddress:
      return 8;
    case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    case MachineJumpTableInfo::EK_LabelDifference32:
    case MachineJumpTableInfo::EK_Custom32:
      return 4;
    case MachineJumpTableInfo::EK_Inline:
      return 0;
    }
    llvm_unreachable("Unknown jump table encoding!");
  }
  
  /// Return the alignment of each entry in the jump table.
  unsigned MachineJumpTableInfo::getEntryAlignment(const DataLayout &TD) const {
    // The alignment of a jump table entry is the alignment of int32 unless the
    // entry is just the address of a block, in which case it is the pointer
    // alignment.
    switch (getEntryKind()) {
    case MachineJumpTableInfo::EK_BlockAddress:
      return TD.getPointerABIAlignment(0).value();
    case MachineJumpTableInfo::EK_GPRel64BlockAddress:
      return TD.getABIIntegerTypeAlignment(64).value();
    case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    case MachineJumpTableInfo::EK_LabelDifference32:
    case MachineJumpTableInfo::EK_Custom32:
      return TD.getABIIntegerTypeAlignment(32).value();
    case MachineJumpTableInfo::EK_Inline:
      return 1;
    }
    llvm_unreachable("Unknown jump table encoding!");
  }
  
  /// Create a new jump table entry in the jump table info.
  unsigned MachineJumpTableInfo::createJumpTableIndex(
                                 const std::vector<MachineBasicBlock*> &DestBBs) {
    assert(!DestBBs.empty() && "Cannot create an empty jump table!");
    JumpTables.push_back(MachineJumpTableEntry(DestBBs));
    return JumpTables.size()-1;
  }
  
  /// If Old is the target of any jump tables, update the jump tables to branch
  /// to New instead.
  bool MachineJumpTableInfo::ReplaceMBBInJumpTables(MachineBasicBlock *Old,
                                                    MachineBasicBlock *New) {
    assert(Old != New && "Not making a change?");
    bool MadeChange = false;
    for (size_t i = 0, e = JumpTables.size(); i != e; ++i)
      ReplaceMBBInJumpTable(i, Old, New);
    return MadeChange;
  }
  
  /// If MBB is present in any jump tables, remove it.
  bool MachineJumpTableInfo::RemoveMBBFromJumpTables(MachineBasicBlock *MBB) {
    bool MadeChange = false;
    for (MachineJumpTableEntry &JTE : JumpTables) {
      auto removeBeginItr = std::remove(JTE.MBBs.begin(), JTE.MBBs.end(), MBB);
      MadeChange |= (removeBeginItr != JTE.MBBs.end());
      JTE.MBBs.erase(removeBeginItr, JTE.MBBs.end());
    }
    return MadeChange;
  }
  
  /// If Old is a target of the jump tables, update the jump table to branch to
  /// New instead.
  bool MachineJumpTableInfo::ReplaceMBBInJumpTable(unsigned Idx,
                                                   MachineBasicBlock *Old,
                                                   MachineBasicBlock *New) {
    assert(Old != New && "Not making a change?");
    bool MadeChange = false;
    MachineJumpTableEntry &JTE = JumpTables[Idx];
    for (size_t j = 0, e = JTE.MBBs.size(); j != e; ++j)
      if (JTE.MBBs[j] == Old) {
        JTE.MBBs[j] = New;
        MadeChange = true;
      }
    return MadeChange;
  }
  
  void MachineJumpTableInfo::print(raw_ostream &OS) const {
    if (JumpTables.empty()) return;
  
    OS << "Jump Tables:\n";
  
    for (unsigned i = 0, e = JumpTables.size(); i != e; ++i) {
      OS << printJumpTableEntryReference(i) << ':';
      for (unsigned j = 0, f = JumpTables[i].MBBs.size(); j != f; ++j)
        OS << ' ' << printMBBReference(*JumpTables[i].MBBs[j]);
      if (i != e)
        OS << '\n';
    }
  
    OS << '\n';
  }
  
  #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void MachineJumpTableInfo::dump() const { print(dbgs()); }
  #endif
  
  Printable llvm::printJumpTableEntryReference(unsigned Idx) {
    return Printable([Idx](raw_ostream &OS) { OS << "%jump-table." << Idx; });
  }
  
  //===----------------------------------------------------------------------===//
  //  MachineConstantPool implementation
  //===----------------------------------------------------------------------===//
  
  void MachineConstantPoolValue::anchor() {}
  
  unsigned MachineConstantPoolValue::getSizeInBytes(const DataLayout &DL) const {
    return DL.getTypeAllocSize(Ty);
  }
  
  unsigned MachineConstantPoolEntry::getSizeInBytes(const DataLayout &DL) const {
    if (isMachineConstantPoolEntry())
      return Val.MachineCPVal->getSizeInBytes(DL);
    return DL.getTypeAllocSize(Val.ConstVal->getType());
  }
  
  bool MachineConstantPoolEntry::needsRelocation() const {
    if (isMachineConstantPoolEntry())
      return true;
    return Val.ConstVal->needsDynamicRelocation();
  }
  
  SectionKind
  MachineConstantPoolEntry::getSectionKind(const DataLayout *DL) const {
    if (needsRelocation())
      return SectionKind::getReadOnlyWithRel();
    switch (getSizeInBytes(*DL)) {
    case 4:
      return SectionKind::getMergeableConst4();
    case 8:
      return SectionKind::getMergeableConst8();
    case 16:
      return SectionKind::getMergeableConst16();
    case 32:
      return SectionKind::getMergeableConst32();
    default:
      return SectionKind::getReadOnly();
    }
  }
  
  MachineConstantPool::~MachineConstantPool() {
    // A constant may be a member of both Constants and MachineCPVsSharingEntries,
    // so keep track of which we've deleted to avoid double deletions.
    DenseSet<MachineConstantPoolValue*> Deleted;
    for (unsigned i = 0, e = Constants.size(); i != e; ++i)
      if (Constants[i].isMachineConstantPoolEntry()) {
        Deleted.insert(Constants[i].Val.MachineCPVal);
        delete Constants[i].Val.MachineCPVal;
      }
    for (MachineConstantPoolValue *CPV : MachineCPVsSharingEntries) {
      if (Deleted.count(CPV) == 0)
        delete CPV;
    }
  }
  
  /// Test whether the given two constants can be allocated the same constant pool
  /// entry.
  static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
                                        const DataLayout &DL) {
    // Handle the trivial case quickly.
    if (A == B) return true;
  
    // If they have the same type but weren't the same constant, quickly
    // reject them.
    if (A->getType() == B->getType()) return false;
  
    // We can't handle structs or arrays.
    if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
        isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
      return false;
  
    // For now, only support constants with the same size.
    uint64_t StoreSize = DL.getTypeStoreSize(A->getType());
    if (StoreSize != DL.getTypeStoreSize(B->getType()) || StoreSize > 128)
      return false;
  
    Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
  
    // Try constant folding a bitcast of both instructions to an integer.  If we
    // get two identical ConstantInt's, then we are good to share them.  We use
    // the constant folding APIs to do this so that we get the benefit of
    // DataLayout.
    if (isa<PointerType>(A->getType()))
      A = ConstantFoldCastOperand(Instruction::PtrToInt,
                                  const_cast<Constant *>(A), IntTy, DL);
    else if (A->getType() != IntTy)
      A = ConstantFoldCastOperand(Instruction::BitCast, const_cast<Constant *>(A),
                                  IntTy, DL);
    if (isa<PointerType>(B->getType()))
      B = ConstantFoldCastOperand(Instruction::PtrToInt,
                                  const_cast<Constant *>(B), IntTy, DL);
    else if (B->getType() != IntTy)
      B = ConstantFoldCastOperand(Instruction::BitCast, const_cast<Constant *>(B),
                                  IntTy, DL);
  
    return A == B;
  }
  
  /// Create a new entry in the constant pool or return an existing one.
  /// User must specify the log2 of the minimum required alignment for the object.
  unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
                                                     Align Alignment) {
    if (Alignment > PoolAlignment) PoolAlignment = Alignment;
  
    // Check to see if we already have this constant.
    //
    // FIXME, this could be made much more efficient for large constant pools.
    for (unsigned i = 0, e = Constants.size(); i != e; ++i)
      if (!Constants[i].isMachineConstantPoolEntry() &&
          CanShareConstantPoolEntry(Constants[i].Val.ConstVal, C, DL)) {
        if (Constants[i].getAlign() < Alignment)
          Constants[i].Alignment = Alignment;
        return i;
      }
  
    Constants.push_back(MachineConstantPoolEntry(C, Alignment));
    return Constants.size()-1;
  }
  
  unsigned MachineConstantPool::getConstantPoolIndex(MachineConstantPoolValue *V,
                                                     Align Alignment) {
    if (Alignment > PoolAlignment) PoolAlignment = Alignment;
  
    // Check to see if we already have this constant.
    //
    // FIXME, this could be made much more efficient for large constant pools.
    int Idx = V->getExistingMachineCPValue(this, Alignment);
    if (Idx != -1) {
      MachineCPVsSharingEntries.insert(V);
      return (unsigned)Idx;
    }
  
    Constants.push_back(MachineConstantPoolEntry(V, Alignment));
    return Constants.size()-1;
  }
  
  void MachineConstantPool::print(raw_ostream &OS) const {
    if (Constants.empty()) return;
  
    OS << "Constant Pool:\n";
    for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
      OS << "  cp#" << i << ": ";
      if (Constants[i].isMachineConstantPoolEntry())
        Constants[i].Val.MachineCPVal->print(OS);
      else
        Constants[i].Val.ConstVal->printAsOperand(OS, /*PrintType=*/false);
      OS << ", align=" << Constants[i].getAlign().value();
      OS << "\n";
    }
  }
  
  #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void MachineConstantPool::dump() const { print(dbgs()); }
  #endif
  