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 //===- 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/SMLoc.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 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();
 
   /// Adds path \p Path to the line string. Returns offset in the
   /// .debug_line_str section.
   size_t addString(StringRef Path);
 };
 
 /// 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,
                    MCSymbol *lineStreamLabel = nullptr,
                    SMLoc streamLabelDefLoc = {})
       : MCDwarfLoc(loc), Label(label), LineStreamLabel(lineStreamLabel),
         StreamLabelDefLoc(streamLabelDefLoc) {}
 
   MCSymbol *getLabel() const { return Label; }
 
   // This is the label that is to be emitted into the line stream. If this is
   // non-null and we need to emit a label, also make sure to restart the current
   // line sequence.
   MCSymbol *LineStreamLabel;
 
   // Location where LineStreamLabel was defined. If there is an error emitting
   // LineStreamLabel, we can use the SMLoc to report an error.
   SMLoc StreamLabelDefLoc;
 
   // 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 HasAnySource = 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());
     HasAnySource |= Source.has_value();
   }
 
   void resetFileTable() {
     MCDwarfDirs.clear();
     MCDwarfFiles.clear();
     RootFile.Name.clear();
     resetMD5Usage();
     HasAnySource = 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);
 
   void endCurrentSeqAndEmitLineStreamLabel(MCStreamer *MCOS, SMLoc DefLoc,
                                            StringRef Name);
 
   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.HasAnySource |= 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, SmallVectorImpl<char> &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 : uint8_t {
     OpSameValue,
     OpRememberState,
     OpRestoreState,
     OpOffset,
     OpLLVMDefAspaceCfa,
     OpDefCfaRegister,
     OpDefCfaOffset,
     OpDefCfa,
     OpRelOffset,
     OpAdjustCfaOffset,
     OpEscape,
     OpRestore,
     OpUndefined,
     OpRegister,
     OpWindowSave,
     OpNegateRAState,
     OpNegateRAStateWithPC,
     OpGnuArgsSize,
     OpLabel,
     OpValOffset,
   };
 
 private:
   MCSymbol *Label;
   union {
     struct {
       unsigned Register;
       int64_t Offset;
     } RI;
     struct {
       unsigned Register;
       int64_t Offset;
       unsigned AddressSpace;
     } RIA;
     struct {
       unsigned Register;
       unsigned Register2;
     } RR;
     MCSymbol *CfiLabel;
   } U;
   OpType Operation;
   SMLoc Loc;
   std::vector<char> Values;
   std::string Comment;
 
   MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int64_t O, SMLoc Loc,
                    StringRef V = "", StringRef Comment = "")
       : Label(L), Operation(Op), Loc(Loc), Values(V.begin(), V.end()),
         Comment(Comment) {
     assert(Op != OpRegister && Op != OpLLVMDefAspaceCfa);
     U.RI = {R, O};
   }
   MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R1, unsigned R2, SMLoc Loc)
       : Label(L), Operation(Op), Loc(Loc) {
     assert(Op == OpRegister);
     U.RR = {R1, R2};
   }
   MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int64_t O, unsigned AS,
                    SMLoc Loc)
       : Label(L), Operation(Op), Loc(Loc) {
     assert(Op == OpLLVMDefAspaceCfa);
     U.RIA = {R, O, AS};
   }
 
   MCCFIInstruction(OpType Op, MCSymbol *L, MCSymbol *CfiLabel, SMLoc Loc)
       : Label(L), Operation(Op), Loc(Loc) {
     assert(Op == OpLabel);
     U.CfiLabel = CfiLabel;
   }
 
 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,
                                     int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpDefCfa, L, Register, Offset, Loc);
   }
 
   /// .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,
                                                SMLoc Loc = {}) {
     return MCCFIInstruction(OpDefCfaRegister, L, Register, INT64_C(0), Loc);
   }
 
   /// .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, int64_t Offset,
                                           SMLoc Loc = {}) {
     return MCCFIInstruction(OpDefCfaOffset, L, 0, Offset, Loc);
   }
 
   /// .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, int64_t Adjustment,
                                                 SMLoc Loc = {}) {
     return MCCFIInstruction(OpAdjustCfaOffset, L, 0, Adjustment, Loc);
   }
 
   // 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,
                                                  int64_t Offset,
                                                  unsigned AddressSpace,
                                                  SMLoc Loc) {
     return MCCFIInstruction(OpLLVMDefAspaceCfa, L, Register, Offset,
                             AddressSpace, Loc);
   }
 
   /// .cfi_offset Previous value of Register is saved at offset Offset
   /// from CFA.
   static MCCFIInstruction createOffset(MCSymbol *L, unsigned Register,
                                        int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpOffset, L, Register, Offset, Loc);
   }
 
   /// .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,
                                           int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpRelOffset, L, Register, Offset, Loc);
   }
 
   /// .cfi_register Previous value of Register1 is saved in
   /// register Register2.
   static MCCFIInstruction createRegister(MCSymbol *L, unsigned Register1,
                                          unsigned Register2, SMLoc Loc = {}) {
     return MCCFIInstruction(OpRegister, L, Register1, Register2, Loc);
   }
 
   /// .cfi_window_save SPARC register window is saved.
   static MCCFIInstruction createWindowSave(MCSymbol *L, SMLoc Loc = {}) {
     return MCCFIInstruction(OpWindowSave, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_negate_ra_state AArch64 negate RA state.
   static MCCFIInstruction createNegateRAState(MCSymbol *L, SMLoc Loc = {}) {
     return MCCFIInstruction(OpNegateRAState, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_negate_ra_state_with_pc AArch64 negate RA state with PC.
   static MCCFIInstruction createNegateRAStateWithPC(MCSymbol *L,
                                                     SMLoc Loc = {}) {
     return MCCFIInstruction(OpNegateRAStateWithPC, L, 0, INT64_C(0), Loc);
   }
 
   /// .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,
                                         SMLoc Loc = {}) {
     return MCCFIInstruction(OpRestore, L, Register, INT64_C(0), Loc);
   }
 
   /// .cfi_undefined From now on the previous value of Register can't be
   /// restored anymore.
   static MCCFIInstruction createUndefined(MCSymbol *L, unsigned Register,
                                           SMLoc Loc = {}) {
     return MCCFIInstruction(OpUndefined, L, Register, INT64_C(0), Loc);
   }
 
   /// .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,
                                           SMLoc Loc = {}) {
     return MCCFIInstruction(OpSameValue, L, Register, INT64_C(0), Loc);
   }
 
   /// .cfi_remember_state Save all current rules for all registers.
   static MCCFIInstruction createRememberState(MCSymbol *L, SMLoc Loc = {}) {
     return MCCFIInstruction(OpRememberState, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_restore_state Restore the previously saved state.
   static MCCFIInstruction createRestoreState(MCSymbol *L, SMLoc Loc = {}) {
     return MCCFIInstruction(OpRestoreState, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_escape Allows the user to add arbitrary bytes to the unwind
   /// info.
   static MCCFIInstruction createEscape(MCSymbol *L, StringRef Vals,
                                        SMLoc Loc = {}, StringRef Comment = "") {
     return MCCFIInstruction(OpEscape, L, 0, 0, Loc, Vals, Comment);
   }
 
   /// A special wrapper for .cfi_escape that indicates GNU_ARGS_SIZE
   static MCCFIInstruction createGnuArgsSize(MCSymbol *L, int64_t Size,
                                             SMLoc Loc = {}) {
     return MCCFIInstruction(OpGnuArgsSize, L, 0, Size, Loc);
   }
 
   static MCCFIInstruction createLabel(MCSymbol *L, MCSymbol *CfiLabel,
                                       SMLoc Loc) {
     return MCCFIInstruction(OpLabel, L, CfiLabel, Loc);
   }
 
   /// .cfi_val_offset Previous value of Register is offset Offset from the
   /// current CFA register.
   static MCCFIInstruction createValOffset(MCSymbol *L, unsigned Register,
                                           int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpValOffset, L, Register, Offset, Loc);
   }
 
   OpType getOperation() const { return Operation; }
   MCSymbol *getLabel() const { return Label; }
 
   unsigned getRegister() const {
     if (Operation == OpRegister)
       return U.RR.Register;
     if (Operation == OpLLVMDefAspaceCfa)
       return U.RIA.Register;
     assert(Operation == OpDefCfa || Operation == OpOffset ||
            Operation == OpRestore || Operation == OpUndefined ||
            Operation == OpSameValue || Operation == OpDefCfaRegister ||
            Operation == OpRelOffset || Operation == OpValOffset);
     return U.RI.Register;
   }
 
   unsigned getRegister2() const {
     assert(Operation == OpRegister);
     return U.RR.Register2;
   }
 
   unsigned getAddressSpace() const {
     assert(Operation == OpLLVMDefAspaceCfa);
     return U.RIA.AddressSpace;
   }
 
   int64_t getOffset() const {
     if (Operation == OpLLVMDefAspaceCfa)
       return U.RIA.Offset;
     assert(Operation == OpDefCfa || Operation == OpOffset ||
            Operation == OpRelOffset || Operation == OpDefCfaOffset ||
            Operation == OpAdjustCfaOffset || Operation == OpGnuArgsSize ||
            Operation == OpValOffset);
     return U.RI.Offset;
   }
 
   MCSymbol *getCfiLabel() const {
     assert(Operation == OpLabel);
     return U.CfiLabel;
   }
 
   StringRef getValues() const {
     assert(Operation == OpEscape);
     return StringRef(&Values[0], Values.size());
   }
 
   StringRef getComment() const { return Comment; }
   SMLoc getLoc() const { return Loc; }
 };
 
 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;
   uint64_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 encodeAdvanceLoc(MCContext &Context, uint64_t AddrDelta,
                                SmallVectorImpl<char> &OS);
 };
 
 } // end namespace llvm
 
 #endif // LLVM_MC_MCDWARF_H

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