Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- MCDwarf.h - Machine Code Dwarf support -------------------*- C++ -*-===//

//

// 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

//

//===----------------------------------------------------------------------===//

//

// This file contains the declaration of the MCDwarfFile to support the dwarf

// .file directive and the .loc directive.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_MCDWARF_H

#define LLVM_MC_MCDWARF_H

#include "llvm/ADT/MapVector.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/StringMap.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/MC/StringTableBuilder.h"

#include "llvm/Support/Error.h"

#include "llvm/Support/MD5.h"

#include "llvm/Support/StringSaver.h"

#include <cassert>

#include <cstdint>

#include <optional>

#include <string>

#include <utility>

#include <vector>

namespace llvm {

template <typename T> class ArrayRef;

class MCAsmBackend;

class MCContext;

class MCObjectStreamer;

class MCSection;

class MCStreamer;

class MCSymbol;

class raw_ostream;

class SMLoc;

class SourceMgr;

namespace mcdwarf {

// Emit the common part of the DWARF 5 range/locations list tables header.

MCSymbol *emitListsTableHeaderStart(MCStreamer &S);

} // namespace mcdwarf

/// Manage the .debug_line_str section contents, if we use it.

class MCDwarfLineStr {

  BumpPtrAllocator Alloc;

  StringSaver Saver{Alloc};

  MCSymbol *LineStrLabel = nullptr;

  StringTableBuilder LineStrings{StringTableBuilder::DWARF};

  bool UseRelocs = false;

public:

  /// Construct an instance that can emit .debug_line_str (for use in a normal

  /// v5 line table).

  explicit MCDwarfLineStr(MCContext &Ctx);

  StringSaver &getSaver() { return Saver; }

  /// Emit a reference to the string.

  void emitRef(MCStreamer *MCOS, StringRef Path);

  /// Emit the .debug_line_str section if appropriate.

  void emitSection(MCStreamer *MCOS);

  /// Returns finalized section.

  SmallString<0> getFinalizedData();

};

/// Instances of this class represent the name of the dwarf .file directive and

/// its associated dwarf file number in the MC file. MCDwarfFile's are created

/// and uniqued by the MCContext class. In Dwarf 4 file numbers start from 1;

/// i.e. the entry with file number 1 is the first element in the vector of

/// DwarfFiles and there is no MCDwarfFile with file number 0. In Dwarf 5 file

/// numbers start from 0, with the MCDwarfFile with file number 0 being the

/// primary source file, and file numbers correspond to their index in the

/// vector.

struct MCDwarfFile {

  // The base name of the file without its directory path.

  std::string Name;

  // The index into the list of directory names for this file name.

  unsigned DirIndex = 0;

  /// The MD5 checksum, if there is one. Non-owning pointer to data allocated

  /// in MCContext.

  std::optional<MD5::MD5Result> Checksum;

  /// The source code of the file. Non-owning reference to data allocated in

  /// MCContext.

  std::optional<StringRef> Source;

};

/// Instances of this class represent the information from a

/// dwarf .loc directive.

class MCDwarfLoc {

  uint32_t FileNum;

  uint32_t Line;

  uint16_t Column;

  // Flags (see #define's below)

  uint8_t Flags;

  uint8_t Isa;

  uint32_t Discriminator;

// Flag that indicates the initial value of the is_stmt_start flag.

#define DWARF2_LINE_DEFAULT_IS_STMT 1

#define DWARF2_FLAG_IS_STMT (1 << 0)

#define DWARF2_FLAG_BASIC_BLOCK (1 << 1)

#define DWARF2_FLAG_PROLOGUE_END (1 << 2)

#define DWARF2_FLAG_EPILOGUE_BEGIN (1 << 3)

private: // MCContext manages these

  friend class MCContext;

  friend class MCDwarfLineEntry;

  MCDwarfLoc(unsigned fileNum, unsigned line, unsigned column, unsigned flags,

             unsigned isa, unsigned discriminator)

      : FileNum(fileNum), Line(line), Column(column), Flags(flags), Isa(isa),

        Discriminator(discriminator) {}

  // Allow the default copy constructor and assignment operator to be used

  // for an MCDwarfLoc object.

public:

  /// Get the FileNum of this MCDwarfLoc.

  unsigned getFileNum() const { return FileNum; }

  /// Get the Line of this MCDwarfLoc.

  unsigned getLine() const { return Line; }

  /// Get the Column of this MCDwarfLoc.

  unsigned getColumn() const { return Column; }

  /// Get the Flags of this MCDwarfLoc.

  unsigned getFlags() const { return Flags; }

  /// Get the Isa of this MCDwarfLoc.

  unsigned getIsa() const { return Isa; }

  /// Get the Discriminator of this MCDwarfLoc.

  unsigned getDiscriminator() const { return Discriminator; }

  /// Set the FileNum of this MCDwarfLoc.

  void setFileNum(unsigned fileNum) { FileNum = fileNum; }

  /// Set the Line of this MCDwarfLoc.

  void setLine(unsigned line) { Line = line; }

  /// Set the Column of this MCDwarfLoc.

  void setColumn(unsigned column) {

    assert(column <= UINT16_MAX);

    Column = column;

  }

  /// Set the Flags of this MCDwarfLoc.

  void setFlags(unsigned flags) {

    assert(flags <= UINT8_MAX);

    Flags = flags;

  }

  /// Set the Isa of this MCDwarfLoc.

  void setIsa(unsigned isa) {

    assert(isa <= UINT8_MAX);

    Isa = isa;

  }

  /// Set the Discriminator of this MCDwarfLoc.

  void setDiscriminator(unsigned discriminator) {

    Discriminator = discriminator;

  }

};

/// Instances of this class represent the line information for

/// the dwarf line table entries.  Which is created after a machine

/// instruction is assembled and uses an address from a temporary label

/// created at the current address in the current section and the info from

/// the last .loc directive seen as stored in the context.

class MCDwarfLineEntry : public MCDwarfLoc {

  MCSymbol *Label;

private:

  // Allow the default copy constructor and assignment operator to be used

  // for an MCDwarfLineEntry object.

public:

  // Constructor to create an MCDwarfLineEntry given a symbol and the dwarf loc.

  MCDwarfLineEntry(MCSymbol *label, const MCDwarfLoc loc)

      : MCDwarfLoc(loc), Label(label) {}

  MCSymbol *getLabel() const { return Label; }

  // This indicates the line entry is synthesized for an end entry.

  bool IsEndEntry = false;

  // Override the label with the given EndLabel.

  void setEndLabel(MCSymbol *EndLabel) {

    Label = EndLabel;

    IsEndEntry = true;

  }

  // This is called when an instruction is assembled into the specified

  // section and if there is information from the last .loc directive that

  // has yet to have a line entry made for it is made.

  static void make(MCStreamer *MCOS, MCSection *Section);

};

/// Instances of this class represent the line information for a compile

/// unit where machine instructions have been assembled after seeing .loc

/// directives.  This is the information used to build the dwarf line

/// table for a section.

class MCLineSection {

public:

  // Add an entry to this MCLineSection's line entries.

  void addLineEntry(const MCDwarfLineEntry &LineEntry, MCSection *Sec) {

    MCLineDivisions[Sec].push_back(LineEntry);

  }

  // Add an end entry by cloning the last entry, if exists, for the section

  // the given EndLabel belongs to. The label is replaced by the given EndLabel.

  void addEndEntry(MCSymbol *EndLabel);

  using MCDwarfLineEntryCollection = std::vector<MCDwarfLineEntry>;

  using iterator = MCDwarfLineEntryCollection::iterator;

  using const_iterator = MCDwarfLineEntryCollection::const_iterator;

  using MCLineDivisionMap = MapVector<MCSection *, MCDwarfLineEntryCollection>;

private:

  // A collection of MCDwarfLineEntry for each section.

  MCLineDivisionMap MCLineDivisions;

public:

  // Returns the collection of MCDwarfLineEntry for a given Compile Unit ID.

  const MCLineDivisionMap &getMCLineEntries() const {

    return MCLineDivisions;

  }

};

struct MCDwarfLineTableParams {

  /// First special line opcode - leave room for the standard opcodes.

  /// Note: If you want to change this, you'll have to update the

  /// "StandardOpcodeLengths" table that is emitted in

  /// \c Emit().

  uint8_t DWARF2LineOpcodeBase = 13;

  /// Minimum line offset in a special line info. opcode.  The value

  /// -5 was chosen to give a reasonable range of values.

  int8_t DWARF2LineBase = -5;

  /// Range of line offsets in a special line info. opcode.

  uint8_t DWARF2LineRange = 14;

};

struct MCDwarfLineTableHeader {

  MCSymbol *Label = nullptr;

  SmallVector<std::string, 3> MCDwarfDirs;

  SmallVector<MCDwarfFile, 3> MCDwarfFiles;

  StringMap<unsigned> SourceIdMap;

  std::string CompilationDir;

  MCDwarfFile RootFile;

  bool HasSource = false;

private:

  bool HasAllMD5 = true;

  bool HasAnyMD5 = false;

public:

  MCDwarfLineTableHeader() = default;

  Expected<unsigned> tryGetFile(StringRef &Directory, StringRef &FileName,

                                std::optional<MD5::MD5Result> Checksum,

                                std::optional<StringRef> Source,

                                uint16_t DwarfVersion, unsigned FileNumber = 0);

  std::pair<MCSymbol *, MCSymbol *>

  Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,

       std::optional<MCDwarfLineStr> &LineStr) const;

  std::pair<MCSymbol *, MCSymbol *>

  Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,

       ArrayRef<char> SpecialOpcodeLengths,

       std::optional<MCDwarfLineStr> &LineStr) const;

  void resetMD5Usage() {

    HasAllMD5 = true;

    HasAnyMD5 = false;

  }

  void trackMD5Usage(bool MD5Used) {

    HasAllMD5 &= MD5Used;

    HasAnyMD5 |= MD5Used;

  }

  bool isMD5UsageConsistent() const {

    return MCDwarfFiles.empty() || (HasAllMD5 == HasAnyMD5);

  }

  void setRootFile(StringRef Directory, StringRef FileName,

                   std::optional<MD5::MD5Result> Checksum,

                   std::optional<StringRef> Source) {

    CompilationDir = std::string(Directory);

    RootFile.Name = std::string(FileName);

    RootFile.DirIndex = 0;

    RootFile.Checksum = Checksum;

    RootFile.Source = Source;

    trackMD5Usage(Checksum.has_value());

    HasSource = Source.has_value();

  }

  void resetFileTable() {

    MCDwarfDirs.clear();

    MCDwarfFiles.clear();

    RootFile.Name.clear();

    resetMD5Usage();

    HasSource = false;

  }

private:

  void emitV2FileDirTables(MCStreamer *MCOS) const;

  void emitV5FileDirTables(MCStreamer *MCOS,

                           std::optional<MCDwarfLineStr> &LineStr) const;

};

class MCDwarfDwoLineTable {

  MCDwarfLineTableHeader Header;

  bool HasSplitLineTable = false;

public:

  void maybeSetRootFile(StringRef Directory, StringRef FileName,

                        std::optional<MD5::MD5Result> Checksum,

                        std::optional<StringRef> Source) {

    if (!Header.RootFile.Name.empty())

      return;

    Header.setRootFile(Directory, FileName, Checksum, Source);

  }

  unsigned getFile(StringRef Directory, StringRef FileName,

                   std::optional<MD5::MD5Result> Checksum,

                   uint16_t DwarfVersion, std::optional<StringRef> Source) {

    HasSplitLineTable = true;

    return cantFail(Header.tryGetFile(Directory, FileName, Checksum, Source,

                                      DwarfVersion));

  }

  void Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,

            MCSection *Section) const;

};

class MCDwarfLineTable {

  MCDwarfLineTableHeader Header;

  MCLineSection MCLineSections;

public:

  // This emits the Dwarf file and the line tables for all Compile Units.

  static void emit(MCStreamer *MCOS, MCDwarfLineTableParams Params);

  // This emits the Dwarf file and the line tables for a given Compile Unit.

  void emitCU(MCStreamer *MCOS, MCDwarfLineTableParams Params,

              std::optional<MCDwarfLineStr> &LineStr) const;

  // This emits a single line table associated with a given Section.

  static void

  emitOne(MCStreamer *MCOS, MCSection *Section,

          const MCLineSection::MCDwarfLineEntryCollection &LineEntries);

  Expected<unsigned> tryGetFile(StringRef &Directory, StringRef &FileName,

                                std::optional<MD5::MD5Result> Checksum,

                                std::optional<StringRef> Source,

                                uint16_t DwarfVersion, unsigned FileNumber = 0);

  unsigned getFile(StringRef &Directory, StringRef &FileName,

                   std::optional<MD5::MD5Result> Checksum,

                   std::optional<StringRef> Source, uint16_t DwarfVersion,

                   unsigned FileNumber = 0) {

    return cantFail(tryGetFile(Directory, FileName, Checksum, Source,

                               DwarfVersion, FileNumber));

  }

  void setRootFile(StringRef Directory, StringRef FileName,

                   std::optional<MD5::MD5Result> Checksum,

                   std::optional<StringRef> Source) {

    Header.CompilationDir = std::string(Directory);

    Header.RootFile.Name = std::string(FileName);

    Header.RootFile.DirIndex = 0;

    Header.RootFile.Checksum = Checksum;

    Header.RootFile.Source = Source;

    Header.trackMD5Usage(Checksum.has_value());

    Header.HasSource = Source.has_value();

  }

  void resetFileTable() { Header.resetFileTable(); }

  bool hasRootFile() const { return !Header.RootFile.Name.empty(); }

  MCDwarfFile &getRootFile() { return Header.RootFile; }

  const MCDwarfFile &getRootFile() const { return Header.RootFile; }

  // Report whether MD5 usage has been consistent (all-or-none).

  bool isMD5UsageConsistent() const { return Header.isMD5UsageConsistent(); }

  MCSymbol *getLabel() const {

    return Header.Label;

  }

  void setLabel(MCSymbol *Label) {

    Header.Label = Label;

  }

  const SmallVectorImpl<std::string> &getMCDwarfDirs() const {

    return Header.MCDwarfDirs;

  }

  SmallVectorImpl<std::string> &getMCDwarfDirs() {

    return Header.MCDwarfDirs;

  }

  const SmallVectorImpl<MCDwarfFile> &getMCDwarfFiles() const {

    return Header.MCDwarfFiles;

  }

  SmallVectorImpl<MCDwarfFile> &getMCDwarfFiles() {

    return Header.MCDwarfFiles;

  }

  const MCLineSection &getMCLineSections() const {

    return MCLineSections;

  }

  MCLineSection &getMCLineSections() {

    return MCLineSections;

  }

};

class MCDwarfLineAddr {

public:

  /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.

  static void Encode(MCContext &Context, MCDwarfLineTableParams Params,

                     int64_t LineDelta, uint64_t AddrDelta, raw_ostream &OS);

  /// Utility function to emit the encoding to a streamer.

  static void Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,

                   int64_t LineDelta, uint64_t AddrDelta);

};

class MCGenDwarfInfo {

public:

  //

  // When generating dwarf for assembly source files this emits the Dwarf

  // sections.

  //

  static void Emit(MCStreamer *MCOS);

};

// When generating dwarf for assembly source files this is the info that is

// needed to be gathered for each symbol that will have a dwarf label.

class MCGenDwarfLabelEntry {

private:

  // Name of the symbol without a leading underbar, if any.

  StringRef Name;

  // The dwarf file number this symbol is in.

  unsigned FileNumber;

  // The line number this symbol is at.

  unsigned LineNumber;

  // The low_pc for the dwarf label is taken from this symbol.

  MCSymbol *Label;

public:

  MCGenDwarfLabelEntry(StringRef name, unsigned fileNumber, unsigned lineNumber,

                       MCSymbol *label)

      : Name(name), FileNumber(fileNumber), LineNumber(lineNumber),

        Label(label) {}

  StringRef getName() const { return Name; }

  unsigned getFileNumber() const { return FileNumber; }

  unsigned getLineNumber() const { return LineNumber; }

  MCSymbol *getLabel() const { return Label; }

  // This is called when label is created when we are generating dwarf for

  // assembly source files.

  static void Make(MCSymbol *Symbol, MCStreamer *MCOS, SourceMgr &SrcMgr,

                   SMLoc &Loc);

};

class MCCFIInstruction {

public:

  enum OpType {

    OpSameValue,

    OpRememberState,

    OpRestoreState,

    OpOffset,

    OpLLVMDefAspaceCfa,

    OpDefCfaRegister,

    OpDefCfaOffset,

    OpDefCfa,

    OpRelOffset,

    OpAdjustCfaOffset,

    OpEscape,

    OpRestore,

    OpUndefined,

    OpRegister,

    OpWindowSave,

    OpNegateRAState,

    OpGnuArgsSize

  };

private:

  OpType Operation;

  MCSymbol *Label;

  unsigned Register;

  union {

    int Offset;

    unsigned Register2;

  };

  unsigned AddressSpace;

  std::vector<char> Values;

  std::string Comment;

  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, StringRef V,

                   StringRef Comment = "")

      : Operation(Op), Label(L), Register(R), Offset(O),

        Values(V.begin(), V.end()), Comment(Comment) {

    assert(Op != OpRegister && Op != OpLLVMDefAspaceCfa);

  }

  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R1, unsigned R2)

      : Operation(Op), Label(L), Register(R1), Register2(R2) {

    assert(Op == OpRegister);

  }

  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, unsigned AS)

      : Operation(Op), Label(L), Register(R), Offset(O), AddressSpace(AS) {

    assert(Op == OpLLVMDefAspaceCfa);

  }

public:

  /// .cfi_def_cfa defines a rule for computing CFA as: take address from

  /// Register and add Offset to it.

  static MCCFIInstruction cfiDefCfa(MCSymbol *L, unsigned Register,

                                    int Offset) {

    return MCCFIInstruction(OpDefCfa, L, Register, Offset, "");

  }

  /// .cfi_def_cfa_register modifies a rule for computing CFA. From now

  /// on Register will be used instead of the old one. Offset remains the same.

  static MCCFIInstruction createDefCfaRegister(MCSymbol *L, unsigned Register) {

    return MCCFIInstruction(OpDefCfaRegister, L, Register, 0, "");

  }

  /// .cfi_def_cfa_offset modifies a rule for computing CFA. Register

  /// remains the same, but offset is new. Note that it is the absolute offset

  /// that will be added to a defined register to the compute CFA address.

  static MCCFIInstruction cfiDefCfaOffset(MCSymbol *L, int Offset) {

    return MCCFIInstruction(OpDefCfaOffset, L, 0, Offset, "");

  }

  /// .cfi_adjust_cfa_offset Same as .cfi_def_cfa_offset, but

  /// Offset is a relative value that is added/subtracted from the previous

  /// offset.

  static MCCFIInstruction createAdjustCfaOffset(MCSymbol *L, int Adjustment) {

    return MCCFIInstruction(OpAdjustCfaOffset, L, 0, Adjustment, "");

  }

  // FIXME: Update the remaining docs to use the new proposal wording.

  /// .cfi_llvm_def_aspace_cfa defines the rule for computing the CFA to

  /// be the result of evaluating the DWARF operation expression

  /// `DW_OP_constu AS; DW_OP_aspace_bregx R, B` as a location description.

  static MCCFIInstruction createLLVMDefAspaceCfa(MCSymbol *L, unsigned Register,

                                                 int Offset,

                                                 unsigned AddressSpace) {

    return MCCFIInstruction(OpLLVMDefAspaceCfa, L, Register, Offset,

                            AddressSpace);

  }

  /// .cfi_offset Previous value of Register is saved at offset Offset

  /// from CFA.

  static MCCFIInstruction createOffset(MCSymbol *L, unsigned Register,

                                       int Offset) {

    return MCCFIInstruction(OpOffset, L, Register, Offset, "");

  }

  /// .cfi_rel_offset Previous value of Register is saved at offset

  /// Offset from the current CFA register. This is transformed to .cfi_offset

  /// using the known displacement of the CFA register from the CFA.

  static MCCFIInstruction createRelOffset(MCSymbol *L, unsigned Register,

                                          int Offset) {

    return MCCFIInstruction(OpRelOffset, L, Register, Offset, "");

  }

  /// .cfi_register Previous value of Register1 is saved in

  /// register Register2.

  static MCCFIInstruction createRegister(MCSymbol *L, unsigned Register1,

                                         unsigned Register2) {

    return MCCFIInstruction(OpRegister, L, Register1, Register2);

  }

  /// .cfi_window_save SPARC register window is saved.

  static MCCFIInstruction createWindowSave(MCSymbol *L) {

    return MCCFIInstruction(OpWindowSave, L, 0, 0, "");

  }

  /// .cfi_negate_ra_state AArch64 negate RA state.

  static MCCFIInstruction createNegateRAState(MCSymbol *L) {

    return MCCFIInstruction(OpNegateRAState, L, 0, 0, "");

  }

  /// .cfi_restore says that the rule for Register is now the same as it

  /// was at the beginning of the function, after all initial instructions added

  /// by .cfi_startproc were executed.

  static MCCFIInstruction createRestore(MCSymbol *L, unsigned Register) {

    return MCCFIInstruction(OpRestore, L, Register, 0, "");

  }

  /// .cfi_undefined From now on the previous value of Register can't be

  /// restored anymore.

  static MCCFIInstruction createUndefined(MCSymbol *L, unsigned Register) {

    return MCCFIInstruction(OpUndefined, L, Register, 0, "");

  }

  /// .cfi_same_value Current value of Register is the same as in the

  /// previous frame. I.e., no restoration is needed.

  static MCCFIInstruction createSameValue(MCSymbol *L, unsigned Register) {

    return MCCFIInstruction(OpSameValue, L, Register, 0, "");

  }

  /// .cfi_remember_state Save all current rules for all registers.

  static MCCFIInstruction createRememberState(MCSymbol *L) {

    return MCCFIInstruction(OpRememberState, L, 0, 0, "");

  }

  /// .cfi_restore_state Restore the previously saved state.

  static MCCFIInstruction createRestoreState(MCSymbol *L) {

    return MCCFIInstruction(OpRestoreState, L, 0, 0, "");

  }

  /// .cfi_escape Allows the user to add arbitrary bytes to the unwind

  /// info.

  static MCCFIInstruction createEscape(MCSymbol *L, StringRef Vals,

                                       StringRef Comment = "") {

    return MCCFIInstruction(OpEscape, L, 0, 0, Vals, Comment);

  }

  /// A special wrapper for .cfi_escape that indicates GNU_ARGS_SIZE

  static MCCFIInstruction createGnuArgsSize(MCSymbol *L, int Size) {

    return MCCFIInstruction(OpGnuArgsSize, L, 0, Size, "");

  }

  OpType getOperation() const { return Operation; }

  MCSymbol *getLabel() const { return Label; }

  unsigned getRegister() const {

    assert(Operation == OpDefCfa || Operation == OpOffset ||

           Operation == OpRestore || Operation == OpUndefined ||

           Operation == OpSameValue || Operation == OpDefCfaRegister ||

           Operation == OpRelOffset || Operation == OpRegister ||

           Operation == OpLLVMDefAspaceCfa);

    return Register;

  }

  unsigned getRegister2() const {

    assert(Operation == OpRegister);

    return Register2;

  }

  unsigned getAddressSpace() const {

    assert(Operation == OpLLVMDefAspaceCfa);

    return AddressSpace;

  }

  int getOffset() const {

    assert(Operation == OpDefCfa || Operation == OpOffset ||

           Operation == OpRelOffset || Operation == OpDefCfaOffset ||

           Operation == OpAdjustCfaOffset || Operation == OpGnuArgsSize ||

           Operation == OpLLVMDefAspaceCfa);

    return Offset;

  }

  StringRef getValues() const {

    assert(Operation == OpEscape);

    return StringRef(&Values[0], Values.size());

  }

  StringRef getComment() const {

    return Comment;

  }

};

struct MCDwarfFrameInfo {

  MCDwarfFrameInfo() = default;

  MCSymbol *Begin = nullptr;

  MCSymbol *End = nullptr;

  const MCSymbol *Personality = nullptr;

  const MCSymbol *Lsda = nullptr;

  std::vector<MCCFIInstruction> Instructions;

  unsigned CurrentCfaRegister = 0;

  unsigned PersonalityEncoding = 0;

  unsigned LsdaEncoding = 0;

  uint32_t CompactUnwindEncoding = 0;

  bool IsSignalFrame = false;

  bool IsSimple = false;

  unsigned RAReg = static_cast<unsigned>(INT_MAX);

  bool IsBKeyFrame = false;

  bool IsMTETaggedFrame = false;

};

class MCDwarfFrameEmitter {

public:

  //

  // This emits the frame info section.

  //

  static void Emit(MCObjectStreamer &streamer, MCAsmBackend *MAB, bool isEH);

  static void EmitAdvanceLoc(MCObjectStreamer &Streamer, uint64_t AddrDelta);

  static void EncodeAdvanceLoc(MCContext &Context, uint64_t AddrDelta,

                               raw_ostream &OS);

};

} // end namespace llvm

#endif // LLVM_MC_MCDWARF_H