text: //===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file assembles .s files and emits ARM ELF .o object files. Different
  // from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
  // delimit regions of data and code.
  //
  //===----------------------------------------------------------------------===//
  
  #include "ARMRegisterInfo.h"
  #include "ARMUnwindOpAsm.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Triple.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/BinaryFormat/ELF.h"
  #include "llvm/MC/MCAsmBackend.h"
  #include "llvm/MC/MCAsmInfo.h"
  #include "llvm/MC/MCAssembler.h"
  #include "llvm/MC/MCCodeEmitter.h"
  #include "llvm/MC/MCContext.h"
  #include "llvm/MC/MCELFStreamer.h"
  #include "llvm/MC/MCExpr.h"
  #include "llvm/MC/MCFixup.h"
  #include "llvm/MC/MCFragment.h"
  #include "llvm/MC/MCInst.h"
  #include "llvm/MC/MCInstPrinter.h"
  #include "llvm/MC/MCRegisterInfo.h"
  #include "llvm/MC/MCSection.h"
  #include "llvm/MC/MCSectionELF.h"
  #include "llvm/MC/MCStreamer.h"
  #include "llvm/MC/MCSubtargetInfo.h"
  #include "llvm/MC/MCSymbol.h"
  #include "llvm/MC/MCSymbolELF.h"
  #include "llvm/MC/SectionKind.h"
  #include "llvm/Support/ARMBuildAttributes.h"
  #include "llvm/Support/ARMEHABI.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/FormattedStream.h"
  #include "llvm/Support/LEB128.h"
  #include "llvm/Support/TargetParser.h"
  #include "llvm/Support/raw_ostream.h"
  #include <algorithm>
  #include <cassert>
  #include <climits>
  #include <cstddef>
  #include <cstdint>
  #include <string>
  
  using namespace llvm;
  
  static std::string GetAEABIUnwindPersonalityName(unsigned Index) {
    assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX &&
           "Invalid personality index");
    return (Twine("__aeabi_unwind_cpp_pr") + Twine(Index)).str();
  }
  
  namespace {
  
  class ARMELFStreamer;
  
  class ARMTargetAsmStreamer : public ARMTargetStreamer {
    formatted_raw_ostream &OS;
    MCInstPrinter &InstPrinter;
    bool IsVerboseAsm;
  
    void emitFnStart() override;
    void emitFnEnd() override;
    void emitCantUnwind() override;
    void emitPersonality(const MCSymbol *Personality) override;
    void emitPersonalityIndex(unsigned Index) override;
    void emitHandlerData() override;
    void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
    void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
    void emitPad(int64_t Offset) override;
    void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
                     bool isVector) override;
    void emitUnwindRaw(int64_t Offset,
                       const SmallVectorImpl<uint8_t> &Opcodes) override;
  
    void switchVendor(StringRef Vendor) override;
    void emitAttribute(unsigned Attribute, unsigned Value) override;
    void emitTextAttribute(unsigned Attribute, StringRef String) override;
    void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
                              StringRef StringValue) override;
    void emitArch(ARM::ArchKind Arch) override;
    void emitArchExtension(unsigned ArchExt) override;
    void emitObjectArch(ARM::ArchKind Arch) override;
    void emitFPU(unsigned FPU) override;
    void emitInst(uint32_t Inst, char Suffix = '\0') override;
    void finishAttributeSection() override;
  
    void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
    void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
  
  public:
    ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
                         MCInstPrinter &InstPrinter, bool VerboseAsm);
  };
  
  ARMTargetAsmStreamer::ARMTargetAsmStreamer(MCStreamer &S,
                                             formatted_raw_ostream &OS,
                                             MCInstPrinter &InstPrinter,
                                             bool VerboseAsm)
      : ARMTargetStreamer(S), OS(OS), InstPrinter(InstPrinter),
        IsVerboseAsm(VerboseAsm) {}
  
  void ARMTargetAsmStreamer::emitFnStart() { OS << "\t.fnstart\n"; }
  void ARMTargetAsmStreamer::emitFnEnd() { OS << "\t.fnend\n"; }
  void ARMTargetAsmStreamer::emitCantUnwind() { OS << "\t.cantunwind\n"; }
  
  void ARMTargetAsmStreamer::emitPersonality(const MCSymbol *Personality) {
    OS << "\t.personality " << Personality->getName() << '\n';
  }
  
  void ARMTargetAsmStreamer::emitPersonalityIndex(unsigned Index) {
    OS << "\t.personalityindex " << Index << '\n';
  }
  
  void ARMTargetAsmStreamer::emitHandlerData() { OS << "\t.handlerdata\n"; }
  
  void ARMTargetAsmStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
                                       int64_t Offset) {
    OS << "\t.setfp\t";
    InstPrinter.printRegName(OS, FpReg);
    OS << ", ";
    InstPrinter.printRegName(OS, SpReg);
    if (Offset)
      OS << ", #" << Offset;
    OS << '\n';
  }
  
  void ARMTargetAsmStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
    assert((Reg != ARM::SP && Reg != ARM::PC) &&
           "the operand of .movsp cannot be either sp or pc");
  
    OS << "\t.movsp\t";
    InstPrinter.printRegName(OS, Reg);
    if (Offset)
      OS << ", #" << Offset;
    OS << '\n';
  }
  
  void ARMTargetAsmStreamer::emitPad(int64_t Offset) {
    OS << "\t.pad\t#" << Offset << '\n';
  }
  
  void ARMTargetAsmStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
                                         bool isVector) {
    assert(RegList.size() && "RegList should not be empty");
    if (isVector)
      OS << "\t.vsave\t{";
    else
      OS << "\t.save\t{";
  
    InstPrinter.printRegName(OS, RegList[0]);
  
    for (unsigned i = 1, e = RegList.size(); i != e; ++i) {
      OS << ", ";
      InstPrinter.printRegName(OS, RegList[i]);
    }
  
    OS << "}\n";
  }
  
  void ARMTargetAsmStreamer::switchVendor(StringRef Vendor) {}
  
  void ARMTargetAsmStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
    OS << "\t.eabi_attribute\t" << Attribute << ", " << Twine(Value);
    if (IsVerboseAsm) {
      StringRef Name = ARMBuildAttrs::AttrTypeAsString(Attribute);
      if (!Name.empty())
        OS << "\t@ " << Name;
    }
    OS << "\n";
  }
  
  void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
                                               StringRef String) {
    switch (Attribute) {
    case ARMBuildAttrs::CPU_name:
      OS << "\t.cpu\t" << String.lower();
      break;
    default:
      OS << "\t.eabi_attribute\t" << Attribute << ", \"" << String << "\"";
      if (IsVerboseAsm) {
        StringRef Name = ARMBuildAttrs::AttrTypeAsString(Attribute);
        if (!Name.empty())
          OS << "\t@ " << Name;
      }
      break;
    }
    OS << "\n";
  }
  
  void ARMTargetAsmStreamer::emitIntTextAttribute(unsigned Attribute,
                                                  unsigned IntValue,
                                                  StringRef StringValue) {
    switch (Attribute) {
    default: llvm_unreachable("unsupported multi-value attribute in asm mode");
    case ARMBuildAttrs::compatibility:
      OS << "\t.eabi_attribute\t" << Attribute << ", " << IntValue;
      if (!StringValue.empty())
        OS << ", \"" << StringValue << "\"";
      if (IsVerboseAsm)
        OS << "\t@ " << ARMBuildAttrs::AttrTypeAsString(Attribute);
      break;
    }
    OS << "\n";
  }
  
  void ARMTargetAsmStreamer::emitArch(ARM::ArchKind Arch) {
    OS << "\t.arch\t" << ARM::getArchName(Arch) << "\n";
  }
  
  void ARMTargetAsmStreamer::emitArchExtension(unsigned ArchExt) {
    OS << "\t.arch_extension\t" << ARM::getArchExtName(ArchExt) << "\n";
  }
  
  void ARMTargetAsmStreamer::emitObjectArch(ARM::ArchKind Arch) {
    OS << "\t.object_arch\t" << ARM::getArchName(Arch) << '\n';
  }
  
  void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
    OS << "\t.fpu\t" << ARM::getFPUName(FPU) << "\n";
  }
  
  void ARMTargetAsmStreamer::finishAttributeSection() {}
  
  void
  ARMTargetAsmStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
    OS << "\t.tlsdescseq\t" << S->getSymbol().getName();
  }
  
  void ARMTargetAsmStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
    const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
  
    OS << "\t.thumb_set\t";
    Symbol->print(OS, MAI);
    OS << ", ";
    Value->print(OS, MAI);
    OS << '\n';
  }
  
  void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
    OS << "\t.inst";
    if (Suffix)
      OS << "." << Suffix;
    OS << "\t0x" << Twine::utohexstr(Inst) << "\n";
  }
  
  void ARMTargetAsmStreamer::emitUnwindRaw(int64_t Offset,
                                        const SmallVectorImpl<uint8_t> &Opcodes) {
    OS << "\t.unwind_raw " << Offset;
    for (SmallVectorImpl<uint8_t>::const_iterator OCI = Opcodes.begin(),
                                                  OCE = Opcodes.end();
         OCI != OCE; ++OCI)
      OS << ", 0x" << Twine::utohexstr(*OCI);
    OS << '\n';
  }
  
  class ARMTargetELFStreamer : public ARMTargetStreamer {
  private:
    // This structure holds all attributes, accounting for
    // their string/numeric value, so we can later emit them
    // in declaration order, keeping all in the same vector
    struct AttributeItem {
      enum {
        HiddenAttribute = 0,
        NumericAttribute,
        TextAttribute,
        NumericAndTextAttributes
      } Type;
      unsigned Tag;
      unsigned IntValue;
      std::string StringValue;
  
      static bool LessTag(const AttributeItem &LHS, const AttributeItem &RHS) {
        // The conformance tag must be emitted first when serialised
        // into an object file. Specifically, the addenda to the ARM ABI
        // states that (2.3.7.4):
        //
        // "To simplify recognition by consumers in the common case of
        // claiming conformity for the whole file, this tag should be
        // emitted first in a file-scope sub-subsection of the first
        // public subsection of the attributes section."
        //
        // So it is special-cased in this comparison predicate when the
        // attributes are sorted in finishAttributeSection().
        return (RHS.Tag != ARMBuildAttrs::conformance) &&
               ((LHS.Tag == ARMBuildAttrs::conformance) || (LHS.Tag < RHS.Tag));
      }
    };
  
    StringRef CurrentVendor;
    unsigned FPU = ARM::FK_INVALID;
    ARM::ArchKind Arch = ARM::ArchKind::INVALID;
    ARM::ArchKind EmittedArch = ARM::ArchKind::INVALID;
    SmallVector<AttributeItem, 64> Contents;
  
    MCSection *AttributeSection = nullptr;
  
    AttributeItem *getAttributeItem(unsigned Attribute) {
      for (size_t i = 0; i < Contents.size(); ++i)
        if (Contents[i].Tag == Attribute)
          return &Contents[i];
      return nullptr;
    }
  
    void setAttributeItem(unsigned Attribute, unsigned Value,
                          bool OverwriteExisting) {
      // Look for existing attribute item
      if (AttributeItem *Item = getAttributeItem(Attribute)) {
        if (!OverwriteExisting)
          return;
        Item->Type = AttributeItem::NumericAttribute;
        Item->IntValue = Value;
        return;
      }
  
      // Create new attribute item
      AttributeItem Item = {
        AttributeItem::NumericAttribute,
        Attribute,
        Value,
        StringRef("")
      };
      Contents.push_back(Item);
    }
  
    void setAttributeItem(unsigned Attribute, StringRef Value,
                          bool OverwriteExisting) {
      // Look for existing attribute item
      if (AttributeItem *Item = getAttributeItem(Attribute)) {
        if (!OverwriteExisting)
          return;
        Item->Type = AttributeItem::TextAttribute;
        Item->StringValue = Value;
        return;
      }
  
      // Create new attribute item
      AttributeItem Item = {
        AttributeItem::TextAttribute,
        Attribute,
        0,
        Value
      };
      Contents.push_back(Item);
    }
  
    void setAttributeItems(unsigned Attribute, unsigned IntValue,
                           StringRef StringValue, bool OverwriteExisting) {
      // Look for existing attribute item
      if (AttributeItem *Item = getAttributeItem(Attribute)) {
        if (!OverwriteExisting)
          return;
        Item->Type = AttributeItem::NumericAndTextAttributes;
        Item->IntValue = IntValue;
        Item->StringValue = StringValue;
        return;
      }
  
      // Create new attribute item
      AttributeItem Item = {
        AttributeItem::NumericAndTextAttributes,
        Attribute,
        IntValue,
        StringValue
      };
      Contents.push_back(Item);
    }
  
    void emitArchDefaultAttributes();
    void emitFPUDefaultAttributes();
  
    ARMELFStreamer &getStreamer();
  
    void emitFnStart() override;
    void emitFnEnd() override;
    void emitCantUnwind() override;
    void emitPersonality(const MCSymbol *Personality) override;
    void emitPersonalityIndex(unsigned Index) override;
    void emitHandlerData() override;
    void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
    void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
    void emitPad(int64_t Offset) override;
    void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
                     bool isVector) override;
    void emitUnwindRaw(int64_t Offset,
                       const SmallVectorImpl<uint8_t> &Opcodes) override;
  
    void switchVendor(StringRef Vendor) override;
    void emitAttribute(unsigned Attribute, unsigned Value) override;
    void emitTextAttribute(unsigned Attribute, StringRef String) override;
    void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
                              StringRef StringValue) override;
    void emitArch(ARM::ArchKind Arch) override;
    void emitObjectArch(ARM::ArchKind Arch) override;
    void emitFPU(unsigned FPU) override;
    void emitInst(uint32_t Inst, char Suffix = '\0') override;
    void finishAttributeSection() override;
    void emitLabel(MCSymbol *Symbol) override;
  
    void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
    void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
  
    size_t calculateContentSize() const;
  
    // Reset state between object emissions
    void reset() override;
  
  public:
    ARMTargetELFStreamer(MCStreamer &S)
      : ARMTargetStreamer(S), CurrentVendor("aeabi") {}
  };
  
  /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
  /// the appropriate points in the object files. These symbols are defined in the
  /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
  ///
  /// In brief: $a, $t or $d should be emitted at the start of each contiguous
  /// region of ARM code, Thumb code or data in a section. In practice, this
  /// emission does not rely on explicit assembler directives but on inherent
  /// properties of the directives doing the emission (e.g. ".byte" is data, "add
  /// r0, r0, r0" an instruction).
  ///
  /// As a result this system is orthogonal to the DataRegion infrastructure used
  /// by MachO. Beware!
  class ARMELFStreamer : public MCELFStreamer {
  public:
    friend class ARMTargetELFStreamer;
  
    ARMELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
                   raw_pwrite_stream &OS, std::unique_ptr<MCCodeEmitter> Emitter,
                   bool IsThumb)
        : MCELFStreamer(Context, std::move(TAB), OS, std::move(Emitter)),
          IsThumb(IsThumb) {
      EHReset();
    }
  
    ~ARMELFStreamer() override = default;
  
    void FinishImpl() override;
  
    // ARM exception handling directives
    void emitFnStart();
    void emitFnEnd();
    void emitCantUnwind();
    void emitPersonality(const MCSymbol *Per);
    void emitPersonalityIndex(unsigned index);
    void emitHandlerData();
    void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
    void emitMovSP(unsigned Reg, int64_t Offset = 0);
    void emitPad(int64_t Offset);
    void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
    void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
  
    void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
      LastMappingSymbols[getCurrentSection().first] = std::move(LastEMSInfo);
      MCELFStreamer::ChangeSection(Section, Subsection);
      auto LastMappingSymbol = LastMappingSymbols.find(Section);
      if (LastMappingSymbol != LastMappingSymbols.end()) {
        LastEMSInfo = std::move(LastMappingSymbol->second);
        return;
      }
      LastEMSInfo.reset(new ElfMappingSymbolInfo(SMLoc(), nullptr, 0));
    }
  
    /// This function is the one used to emit instruction data into the ELF
    /// streamer. We override it to add the appropriate mapping symbol if
    /// necessary.
    void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
                         bool) override {
      if (IsThumb)
        EmitThumbMappingSymbol();
      else
        EmitARMMappingSymbol();
  
      MCELFStreamer::EmitInstruction(Inst, STI);
    }
  
    void emitInst(uint32_t Inst, char Suffix) {
      unsigned Size;
      char Buffer[4];
      const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
  
      switch (Suffix) {
      case '\0':
        Size = 4;
  
        assert(!IsThumb);
        EmitARMMappingSymbol();
        for (unsigned II = 0, IE = Size; II != IE; II++) {
          const unsigned I = LittleEndian ? (Size - II - 1) : II;
          Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
        }
  
        break;
      case 'n':
      case 'w':
        Size = (Suffix == 'n' ? 2 : 4);
  
        assert(IsThumb);
        EmitThumbMappingSymbol();
        for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
          const unsigned I0 = LittleEndian ? II + 0 : (Size - II - 1);
          const unsigned I1 = LittleEndian ? II + 1 : (Size - II - 2);
          Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
          Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
        }
  
        break;
      default:
        llvm_unreachable("Invalid Suffix");
      }
  
      MCELFStreamer::EmitBytes(StringRef(Buffer, Size));
    }
  
    /// This is one of the functions used to emit data into an ELF section, so the
    /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
    /// necessary.
    void EmitBytes(StringRef Data) override {
      EmitDataMappingSymbol();
      MCELFStreamer::EmitBytes(Data);
    }
  
    void FlushPendingMappingSymbol() {
      if (!LastEMSInfo->hasInfo())
        return;
      ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
      EmitMappingSymbol("$d", EMS->Loc, EMS->F, EMS->Offset);
      EMS->resetInfo();
    }
  
    /// This is one of the functions used to emit data into an ELF section, so the
    /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
    /// necessary.
    void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
      if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
        if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
          getContext().reportError(Loc, "relocated expression must be 32-bit");
          return;
        }
        getOrCreateDataFragment();
      }
  
      EmitDataMappingSymbol();
      MCELFStreamer::EmitValueImpl(Value, Size, Loc);
    }
  
    void EmitAssemblerFlag(MCAssemblerFlag Flag) override {
      MCELFStreamer::EmitAssemblerFlag(Flag);
  
      switch (Flag) {
      case MCAF_SyntaxUnified:
        return; // no-op here.
      case MCAF_Code16:
        IsThumb = true;
        return; // Change to Thumb mode
      case MCAF_Code32:
        IsThumb = false;
        return; // Change to ARM mode
      case MCAF_Code64:
        return;
      case MCAF_SubsectionsViaSymbols:
        return;
      }
    }
  
  private:
    enum ElfMappingSymbol {
      EMS_None,
      EMS_ARM,
      EMS_Thumb,
      EMS_Data
    };
  
    struct ElfMappingSymbolInfo {
      explicit ElfMappingSymbolInfo(SMLoc Loc, MCFragment *F, uint64_t O)
          : Loc(Loc), F(F), Offset(O), State(EMS_None) {}
      void resetInfo() {
        F = nullptr;
        Offset = 0;
      }
      bool hasInfo() { return F != nullptr; }
      SMLoc Loc;
      MCFragment *F;
      uint64_t Offset;
      ElfMappingSymbol State;
    };
  
    void EmitDataMappingSymbol() {
      if (LastEMSInfo->State == EMS_Data)
        return;
      else if (LastEMSInfo->State == EMS_None) {
        // This is a tentative symbol, it won't really be emitted until it's
        // actually needed.
        ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
        auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
        if (!DF)
          return;
        EMS->Loc = SMLoc();
        EMS->F = getCurrentFragment();
        EMS->Offset = DF->getContents().size();
        LastEMSInfo->State = EMS_Data;
        return;
      }
      EmitMappingSymbol("$d");
      LastEMSInfo->State = EMS_Data;
    }
  
    void EmitThumbMappingSymbol() {
      if (LastEMSInfo->State == EMS_Thumb)
        return;
      FlushPendingMappingSymbol();
      EmitMappingSymbol("$t");
      LastEMSInfo->State = EMS_Thumb;
    }
  
    void EmitARMMappingSymbol() {
      if (LastEMSInfo->State == EMS_ARM)
        return;
      FlushPendingMappingSymbol();
      EmitMappingSymbol("$a");
      LastEMSInfo->State = EMS_ARM;
    }
  
    void EmitMappingSymbol(StringRef Name) {
      auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
          Name + "." + Twine(MappingSymbolCounter++)));
      EmitLabel(Symbol);
  
      Symbol->setType(ELF::STT_NOTYPE);
      Symbol->setBinding(ELF::STB_LOCAL);
      Symbol->setExternal(false);
    }
  
    void EmitMappingSymbol(StringRef Name, SMLoc Loc, MCFragment *F,
                           uint64_t Offset) {
      auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
          Name + "." + Twine(MappingSymbolCounter++)));
      EmitLabel(Symbol, Loc, F);
      Symbol->setType(ELF::STT_NOTYPE);
      Symbol->setBinding(ELF::STB_LOCAL);
      Symbol->setExternal(false);
      Symbol->setOffset(Offset);
    }
  
    void EmitThumbFunc(MCSymbol *Func) override {
      getAssembler().setIsThumbFunc(Func);
      EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
    }
  
    // Helper functions for ARM exception handling directives
    void EHReset();
  
    // Reset state between object emissions
    void reset() override;
  
    void EmitPersonalityFixup(StringRef Name);
    void FlushPendingOffset();
    void FlushUnwindOpcodes(bool NoHandlerData);
  
    void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
                           SectionKind Kind, const MCSymbol &Fn);
    void SwitchToExTabSection(const MCSymbol &FnStart);
    void SwitchToExIdxSection(const MCSymbol &FnStart);
  
    void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
  
    bool IsThumb;
    int64_t MappingSymbolCounter = 0;
  
    DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
        LastMappingSymbols;
  
    std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
  
    // ARM Exception Handling Frame Information
    MCSymbol *ExTab;
    MCSymbol *FnStart;
    const MCSymbol *Personality;
    unsigned PersonalityIndex;
    unsigned FPReg; // Frame pointer register
    int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
    int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
    int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
    bool UsedFP;
    bool CantUnwind;
    SmallVector<uint8_t, 64> Opcodes;
    UnwindOpcodeAssembler UnwindOpAsm;
  };
  
  } // end anonymous namespace
  
  ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
    return static_cast<ARMELFStreamer &>(Streamer);
  }
  
  void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
  void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
  void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
  
  void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
    getStreamer().emitPersonality(Personality);
  }
  
  void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
    getStreamer().emitPersonalityIndex(Index);
  }
  
  void ARMTargetELFStreamer::emitHandlerData() {
    getStreamer().emitHandlerData();
  }
  
  void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
                                       int64_t Offset) {
    getStreamer().emitSetFP(FpReg, SpReg, Offset);
  }
  
  void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
    getStreamer().emitMovSP(Reg, Offset);
  }
  
  void ARMTargetELFStreamer::emitPad(int64_t Offset) {
    getStreamer().emitPad(Offset);
  }
  
  void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
                                         bool isVector) {
    getStreamer().emitRegSave(RegList, isVector);
  }
  
  void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
                                        const SmallVectorImpl<uint8_t> &Opcodes) {
    getStreamer().emitUnwindRaw(Offset, Opcodes);
  }
  
  void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
    assert(!Vendor.empty() && "Vendor cannot be empty.");
  
    if (CurrentVendor == Vendor)
      return;
  
    if (!CurrentVendor.empty())
      finishAttributeSection();
  
    assert(Contents.empty() &&
           ".ARM.attributes should be flushed before changing vendor");
    CurrentVendor = Vendor;
  
  }
  
  void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
    setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
  }
  
  void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
                                               StringRef Value) {
    setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
  }
  
  void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
                                                  unsigned IntValue,
                                                  StringRef StringValue) {
    setAttributeItems(Attribute, IntValue, StringValue,
                      /* OverwriteExisting= */ true);
  }
  
  void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
    Arch = Value;
  }
  
  void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
    EmittedArch = Value;
  }
  
  void ARMTargetELFStreamer::emitArchDefaultAttributes() {
    using namespace ARMBuildAttrs;
  
    setAttributeItem(CPU_name,
                     ARM::getCPUAttr(Arch),
                     false);
  
    if (EmittedArch == ARM::ArchKind::INVALID)
      setAttributeItem(CPU_arch,
                       ARM::getArchAttr(Arch),
                       false);
    else
      setAttributeItem(CPU_arch,
                       ARM::getArchAttr(EmittedArch),
                       false);
  
    switch (Arch) {
    case ARM::ArchKind::ARMV2:
    case ARM::ArchKind::ARMV2A:
    case ARM::ArchKind::ARMV3:
    case ARM::ArchKind::ARMV3M:
    case ARM::ArchKind::ARMV4:
      setAttributeItem(ARM_ISA_use, Allowed, false);
      break;
  
    case ARM::ArchKind::ARMV4T:
    case ARM::ArchKind::ARMV5T:
    case ARM::ArchKind::ARMV5TE:
    case ARM::ArchKind::ARMV6:
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, Allowed, false);
      break;
  
    case ARM::ArchKind::ARMV6T2:
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
      break;
  
    case ARM::ArchKind::ARMV6K:
    case ARM::ArchKind::ARMV6KZ:
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, Allowed, false);
      setAttributeItem(Virtualization_use, AllowTZ, false);
      break;
  
    case ARM::ArchKind::ARMV6M:
      setAttributeItem(THUMB_ISA_use, Allowed, false);
      break;
  
    case ARM::ArchKind::ARMV7A:
      setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
      break;
  
    case ARM::ArchKind::ARMV7R:
      setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
      break;
  
    case ARM::ArchKind::ARMV7EM:
    case ARM::ArchKind::ARMV7M:
      setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
      setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
      break;
  
    case ARM::ArchKind::ARMV8A:
    case ARM::ArchKind::ARMV8_1A:
    case ARM::ArchKind::ARMV8_2A:
      setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
      setAttributeItem(MPextension_use, Allowed, false);
      setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
      break;
  
    case ARM::ArchKind::ARMV8MBaseline:
    case ARM::ArchKind::ARMV8MMainline:
      setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
      setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
      break;
  
    case ARM::ArchKind::IWMMXT:
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, Allowed, false);
      setAttributeItem(WMMX_arch, AllowWMMXv1, false);
      break;
  
    case ARM::ArchKind::IWMMXT2:
      setAttributeItem(ARM_ISA_use, Allowed, false);
      setAttributeItem(THUMB_ISA_use, Allowed, false);
      setAttributeItem(WMMX_arch, AllowWMMXv2, false);
      break;
  
    default:
      report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
      break;
    }
  }
  
  void ARMTargetELFStreamer::emitFPU(unsigned Value) {
    FPU = Value;
  }
  
  void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
    switch (FPU) {
    case ARM::FK_VFP:
    case ARM::FK_VFPV2:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv2,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_VFPV3:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3A,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_VFPV3_FP16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3A,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::FP_HP_extension,
                       ARMBuildAttrs::AllowHPFP,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_VFPV3_D16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3B,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_VFPV3_D16_FP16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3B,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::FP_HP_extension,
                       ARMBuildAttrs::AllowHPFP,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_VFPV3XD:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3B,
                       /* OverwriteExisting= */ false);
      break;
    case ARM::FK_VFPV3XD_FP16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3B,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::FP_HP_extension,
                       ARMBuildAttrs::AllowHPFP,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_VFPV4:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv4A,
                       /* OverwriteExisting= */ false);
      break;
  
    // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
    // as _D16 here.
    case ARM::FK_FPV4_SP_D16:
    case ARM::FK_VFPV4_D16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv4B,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_FP_ARMV8:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPARMv8A,
                       /* OverwriteExisting= */ false);
      break;
  
    // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
    // uses the FP_ARMV8_D16 build attribute.
    case ARM::FK_FPV5_SP_D16:
    case ARM::FK_FPV5_D16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPARMv8B,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_NEON:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3A,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
                       ARMBuildAttrs::AllowNeon,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_NEON_FP16:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv3A,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
                       ARMBuildAttrs::AllowNeon,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::FP_HP_extension,
                       ARMBuildAttrs::AllowHPFP,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_NEON_VFPV4:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPv4A,
                       /* OverwriteExisting= */ false);
      setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
                       ARMBuildAttrs::AllowNeon2,
                       /* OverwriteExisting= */ false);
      break;
  
    case ARM::FK_NEON_FP_ARMV8:
    case ARM::FK_CRYPTO_NEON_FP_ARMV8:
      setAttributeItem(ARMBuildAttrs::FP_arch,
                       ARMBuildAttrs::AllowFPARMv8A,
                       /* OverwriteExisting= */ false);
      // 'Advanced_SIMD_arch' must be emitted not here, but within
      // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
      break;
  
    case ARM::FK_SOFTVFP:
    case ARM::FK_NONE:
      break;
  
    default:
      report_fatal_error("Unknown FPU: " + Twine(FPU));
      break;
    }
  }
  
  size_t ARMTargetELFStreamer::calculateContentSize() const {
    size_t Result = 0;
    for (size_t i = 0; i < Contents.size(); ++i) {
      AttributeItem item = Contents[i];
      switch (item.Type) {
      case AttributeItem::HiddenAttribute:
        break;
      case AttributeItem::NumericAttribute:
        Result += getULEB128Size(item.Tag);
        Result += getULEB128Size(item.IntValue);
        break;
      case AttributeItem::TextAttribute:
        Result += getULEB128Size(item.Tag);
        Result += item.StringValue.size() + 1; // string + '\0'
        break;
      case AttributeItem::NumericAndTextAttributes:
        Result += getULEB128Size(item.Tag);
        Result += getULEB128Size(item.IntValue);
        Result += item.StringValue.size() + 1; // string + '\0';
        break;
      }
    }
    return Result;
  }
  
  void ARMTargetELFStreamer::finishAttributeSection() {
    // <format-version>
    // [ <section-length> "vendor-name"
    // [ <file-tag> <size> <attribute>*
    //   | <section-tag> <size> <section-number>* 0 <attribute>*
    //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
    //   ]+
    // ]*
  
    if (FPU != ARM::FK_INVALID)
      emitFPUDefaultAttributes();
  
    if (Arch != ARM::ArchKind::INVALID)
      emitArchDefaultAttributes();
  
    if (Contents.empty())
      return;
  
    std::sort(Contents.begin(), Contents.end(), AttributeItem::LessTag);
  
    ARMELFStreamer &Streamer = getStreamer();
  
    // Switch to .ARM.attributes section
    if (AttributeSection) {
      Streamer.SwitchSection(AttributeSection);
    } else {
      AttributeSection = Streamer.getContext().getELFSection(
          ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
      Streamer.SwitchSection(AttributeSection);
  
      // Format version
      Streamer.EmitIntValue(0x41, 1);
    }
  
    // Vendor size + Vendor name + '\0'
    const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
  
    // Tag + Tag Size
    const size_t TagHeaderSize = 1 + 4;
  
    const size_t ContentsSize = calculateContentSize();
  
    Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
    Streamer.EmitBytes(CurrentVendor);
    Streamer.EmitIntValue(0, 1); // '\0'
  
    Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
    Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
  
    // Size should have been accounted for already, now
    // emit each field as its type (ULEB or String)
    for (size_t i = 0; i < Contents.size(); ++i) {
      AttributeItem item = Contents[i];
      Streamer.EmitULEB128IntValue(item.Tag);
      switch (item.Type) {
      default: llvm_unreachable("Invalid attribute type");
      case AttributeItem::NumericAttribute:
        Streamer.EmitULEB128IntValue(item.IntValue);
        break;
      case AttributeItem::TextAttribute:
        Streamer.EmitBytes(item.StringValue);
        Streamer.EmitIntValue(0, 1); // '\0'
        break;
      case AttributeItem::NumericAndTextAttributes:
        Streamer.EmitULEB128IntValue(item.IntValue);
        Streamer.EmitBytes(item.StringValue);
        Streamer.EmitIntValue(0, 1); // '\0'
        break;
      }
    }
  
    Contents.clear();
    FPU = ARM::FK_INVALID;
  }
  
  void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
    ARMELFStreamer &Streamer = getStreamer();
    if (!Streamer.IsThumb)
      return;
  
    Streamer.getAssembler().registerSymbol(*Symbol);
    unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
    if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
      Streamer.EmitThumbFunc(Symbol);
  }
  
  void
  ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
    getStreamer().EmitFixup(S, FK_Data_4);
  }
  
  void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
    if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
      const MCSymbol &Sym = SRE->getSymbol();
      if (!Sym.isDefined()) {
        getStreamer().EmitAssignment(Symbol, Value);
        return;
      }
    }
  
    getStreamer().EmitThumbFunc(Symbol);
    getStreamer().EmitAssignment(Symbol, Value);
  }
  
  void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
    getStreamer().emitInst(Inst, Suffix);
  }
  
  void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
  
  void ARMELFStreamer::FinishImpl() {
    MCTargetStreamer &TS = *getTargetStreamer();
    ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
    ATS.finishAttributeSection();
  
    MCELFStreamer::FinishImpl();
  }
  
  void ARMELFStreamer::reset() {
    MCTargetStreamer &TS = *getTargetStreamer();
    ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
    ATS.reset();
    MappingSymbolCounter = 0;
    MCELFStreamer::reset();
    LastMappingSymbols.clear();
    LastEMSInfo.reset();
    // MCELFStreamer clear's the assembler's e_flags. However, for
    // arm we manually set the ABI version on streamer creation, so
    // do the same here
    getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
  }
  
  inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
                                                unsigned Type,
                                                unsigned Flags,
                                                SectionKind Kind,
                                                const MCSymbol &Fn) {
    const MCSectionELF &FnSection =
      static_cast<const MCSectionELF &>(Fn.getSection());
  
    // Create the name for new section
    StringRef FnSecName(FnSection.getSectionName());
    SmallString<128> EHSecName(Prefix);
    if (FnSecName != ".text") {
      EHSecName += FnSecName;
    }
  
    // Get .ARM.extab or .ARM.exidx section
    const MCSymbolELF *Group = FnSection.getGroup();
    if (Group)
      Flags |= ELF::SHF_GROUP;
    MCSectionELF *EHSection = getContext().getELFSection(
        EHSecName, Type, Flags, 0, Group, FnSection.getUniqueID(),
        static_cast<const MCSymbolELF *>(&Fn));
  
    assert(EHSection && "Failed to get the required EH section");
  
    // Switch to .ARM.extab or .ARM.exidx section
    SwitchSection(EHSection);
    EmitCodeAlignment(4);
  }
  
  inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
    SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
                      SectionKind::getData(), FnStart);
  }
  
  inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
    SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
                      ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
                      SectionKind::getData(), FnStart);
  }
  
  void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
    MCDataFragment *Frag = getOrCreateDataFragment();
    Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
                                                Kind));
  }
  
  void ARMELFStreamer::EHReset() {
    ExTab = nullptr;
    FnStart = nullptr;
    Personality = nullptr;
    PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
    FPReg = ARM::SP;
    FPOffset = 0;
    SPOffset = 0;
    PendingOffset = 0;
    UsedFP = false;
    CantUnwind = false;
  
    Opcodes.clear();
    UnwindOpAsm.Reset();
  }
  
  void ARMELFStreamer::emitFnStart() {
    assert(FnStart == nullptr);
    FnStart = getContext().createTempSymbol();
    EmitLabel(FnStart);
  }
  
  void ARMELFStreamer::emitFnEnd() {
    assert(FnStart && ".fnstart must precedes .fnend");
  
    // Emit unwind opcodes if there is no .handlerdata directive
    if (!ExTab && !CantUnwind)
      FlushUnwindOpcodes(true);
  
    // Emit the exception index table entry
    SwitchToExIdxSection(*FnStart);
  
    if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX)
      EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
  
    const MCSymbolRefExpr *FnStartRef =
      MCSymbolRefExpr::create(FnStart,
                              MCSymbolRefExpr::VK_ARM_PREL31,
                              getContext());
  
    EmitValue(FnStartRef, 4);
  
    if (CantUnwind) {
      EmitIntValue(ARM::EHABI::EXIDX_CANTUNWIND, 4);
    } else if (ExTab) {
      // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
      const MCSymbolRefExpr *ExTabEntryRef =
        MCSymbolRefExpr::create(ExTab,
                                MCSymbolRefExpr::VK_ARM_PREL31,
                                getContext());
      EmitValue(ExTabEntryRef, 4);
    } else {
      // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
      // the second word of exception index table entry.  The size of the unwind
      // opcodes should always be 4 bytes.
      assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
             "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
      assert(Opcodes.size() == 4u &&
             "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
      uint64_t Intval = Opcodes[0] |
                        Opcodes[1] << 8 |
                        Opcodes[2] << 16 |
                        Opcodes[3] << 24;
      EmitIntValue(Intval, Opcodes.size());
    }
  
    // Switch to the section containing FnStart
    SwitchSection(&FnStart->getSection());
  
    // Clean exception handling frame information
    EHReset();
  }
  
  void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
  
  // Add the R_ARM_NONE fixup at the same position
  void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
    const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
  
    const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
        PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
  
    visitUsedExpr(*PersonalityRef);
    MCDataFragment *DF = getOrCreateDataFragment();
    DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
                                              PersonalityRef,
                                              MCFixup::getKindForSize(4, false)));
  }
  
  void ARMELFStreamer::FlushPendingOffset() {
    if (PendingOffset != 0) {
      UnwindOpAsm.EmitSPOffset(-PendingOffset);
      PendingOffset = 0;
    }
  }
  
  void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
    // Emit the unwind opcode to restore $sp.
    if (UsedFP) {
      const MCRegisterInfo *MRI = getContext().getRegisterInfo();
      int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
      UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
      UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
    } else {
      FlushPendingOffset();
    }
  
    // Finalize the unwind opcode sequence
    UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
  
    // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
    // section.  Thus, we don't have to create an entry in the .ARM.extab
    // section.
    if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
      return;
  
    // Switch to .ARM.extab section.
    SwitchToExTabSection(*FnStart);
  
    // Create .ARM.extab label for offset in .ARM.exidx
    assert(!ExTab);
    ExTab = getContext().createTempSymbol();
    EmitLabel(ExTab);
  
    // Emit personality
    if (Personality) {
      const MCSymbolRefExpr *PersonalityRef =
        MCSymbolRefExpr::create(Personality,
                                MCSymbolRefExpr::VK_ARM_PREL31,
                                getContext());
  
      EmitValue(PersonalityRef, 4);
    }
  
    // Emit unwind opcodes
    assert((Opcodes.size() % 4) == 0 &&
           "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
    for (unsigned I = 0; I != Opcodes.size(); I += 4) {
      uint64_t Intval = Opcodes[I] |
                        Opcodes[I + 1] << 8 |
                        Opcodes[I + 2] << 16 |
                        Opcodes[I + 3] << 24;
      EmitIntValue(Intval, 4);
    }
  
    // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
    // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
    // after the unwind opcodes.  The handler data consists of several 32-bit
    // words, and should be terminated by zero.
    //
    // In case that the .handlerdata directive is not specified by the
    // programmer, we should emit zero to terminate the handler data.
    if (NoHandlerData && !Personality)
      EmitIntValue(0, 4);
  }
  
  void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
  
  void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
    Personality = Per;
    UnwindOpAsm.setPersonality(Per);
  }
  
  void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
    assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
    PersonalityIndex = Index;
  }
  
  void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
                                 int64_t Offset) {
    assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
           "the operand of .setfp directive should be either $sp or $fp");
  
    UsedFP = true;
    FPReg = NewFPReg;
  
    if (NewSPReg == ARM::SP)
      FPOffset = SPOffset + Offset;
    else
      FPOffset += Offset;
  }
  
  void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
    assert((Reg != ARM::SP && Reg != ARM::PC) &&
           "the operand of .movsp cannot be either sp or pc");
    assert(FPReg == ARM::SP && "current FP must be SP");
  
    FlushPendingOffset();
  
    FPReg = Reg;
    FPOffset = SPOffset + Offset;
  
    const MCRegisterInfo *MRI = getContext().getRegisterInfo();
    UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
  }
  
  void ARMELFStreamer::emitPad(int64_t Offset) {
    // Track the change of the $sp offset
    SPOffset -= Offset;
  
    // To squash multiple .pad directives, we should delay the unwind opcode
    // until the .save, .vsave, .handlerdata, or .fnend directives.
    PendingOffset -= Offset;
  }
  
  void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
                                   bool IsVector) {
    // Collect the registers in the register list
    unsigned Count = 0;
    uint32_t Mask = 0;
    const MCRegisterInfo *MRI = getContext().getRegisterInfo();
    for (size_t i = 0; i < RegList.size(); ++i) {
      unsigned Reg = MRI->getEncodingValue(RegList[i]);
      assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
      unsigned Bit = (1u << Reg);
      if ((Mask & Bit) == 0) {
        Mask |= Bit;
        ++Count;
      }
    }
  
    // Track the change the $sp offset: For the .save directive, the
    // corresponding push instruction will decrease the $sp by (4 * Count).
    // For the .vsave directive, the corresponding vpush instruction will
    // decrease $sp by (8 * Count).
    SPOffset -= Count * (IsVector ? 8 : 4);
  
    // Emit the opcode
    FlushPendingOffset();
    if (IsVector)
      UnwindOpAsm.EmitVFPRegSave(Mask);
    else
      UnwindOpAsm.EmitRegSave(Mask);
  }
  
  void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
                                     const SmallVectorImpl<uint8_t> &Opcodes) {
    FlushPendingOffset();
    SPOffset = SPOffset - Offset;
    UnwindOpAsm.EmitRaw(Opcodes);
  }
  
  namespace llvm {
  
  MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
                                               formatted_raw_ostream &OS,
                                               MCInstPrinter *InstPrint,
                                               bool isVerboseAsm) {
    return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
  }
  
  MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
    return new ARMTargetStreamer(S);
  }
  
  MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
                                                  const MCSubtargetInfo &STI) {
    const Triple &TT = STI.getTargetTriple();
    if (TT.isOSBinFormatELF())
      return new ARMTargetELFStreamer(S);
    return new ARMTargetStreamer(S);
  }
  
  MCELFStreamer *createARMELFStreamer(MCContext &Context,
                                      std::unique_ptr<MCAsmBackend> TAB,
                                      raw_pwrite_stream &OS,
                                      std::unique_ptr<MCCodeEmitter> Emitter,
                                      bool RelaxAll, bool IsThumb) {
    ARMELFStreamer *S = new ARMELFStreamer(Context, std::move(TAB), OS,
                                           std::move(Emitter), IsThumb);
    // FIXME: This should eventually end up somewhere else where more
    // intelligent flag decisions can be made. For now we are just maintaining
    // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
    S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
  
    if (RelaxAll)
      S->getAssembler().setRelaxAll(true);
    return S;
  }
  
  } // end namespace llvm
  