text: //===- MCContext.h - Machine Code Context -----------------------*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_MC_MCCONTEXT_H
  #define LLVM_MC_MCCONTEXT_H
  
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/SetVector.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringMap.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/BinaryFormat/Dwarf.h"
  #include "llvm/MC/MCAsmMacro.h"
  #include "llvm/MC/MCDwarf.h"
  #include "llvm/MC/MCSubtargetInfo.h"
  #include "llvm/MC/SectionKind.h"
  #include "llvm/Support/Allocator.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/raw_ostream.h"
  #include <algorithm>
  #include <cassert>
  #include <cstddef>
  #include <cstdint>
  #include <map>
  #include <memory>
  #include <string>
  #include <utility>
  #include <vector>
  
  namespace llvm {
  
    class CodeViewContext;
    class MCAsmInfo;
    class MCLabel;
    class MCObjectFileInfo;
    class MCRegisterInfo;
    class MCSection;
    class MCSectionCOFF;
    class MCSectionELF;
    class MCSectionMachO;
    class MCSectionWasm;
    class MCStreamer;
    class MCSymbol;
    class MCSymbolELF;
    class MCSymbolWasm;
    class SMLoc;
    class SourceMgr;
  
    /// Context object for machine code objects.  This class owns all of the
    /// sections that it creates.
    ///
    class MCContext {
    public:
      using SymbolTable = StringMap<MCSymbol *, BumpPtrAllocator &>;
  
    private:
      /// The SourceMgr for this object, if any.
      const SourceMgr *SrcMgr;
  
      /// The SourceMgr for inline assembly, if any.
      SourceMgr *InlineSrcMgr;
  
      /// The MCAsmInfo for this target.
      const MCAsmInfo *MAI;
  
      /// The MCRegisterInfo for this target.
      const MCRegisterInfo *MRI;
  
      /// The MCObjectFileInfo for this target.
      const MCObjectFileInfo *MOFI;
  
      std::unique_ptr<CodeViewContext> CVContext;
  
      /// Allocator object used for creating machine code objects.
      ///
      /// We use a bump pointer allocator to avoid the need to track all allocated
      /// objects.
      BumpPtrAllocator Allocator;
  
      SpecificBumpPtrAllocator<MCSectionCOFF> COFFAllocator;
      SpecificBumpPtrAllocator<MCSectionELF> ELFAllocator;
      SpecificBumpPtrAllocator<MCSectionMachO> MachOAllocator;
      SpecificBumpPtrAllocator<MCSectionWasm> WasmAllocator;
  
      /// Bindings of names to symbols.
      SymbolTable Symbols;
  
      /// A mapping from a local label number and an instance count to a symbol.
      /// For example, in the assembly
      ///     1:
      ///     2:
      ///     1:
      /// We have three labels represented by the pairs (1, 0), (2, 0) and (1, 1)
      DenseMap<std::pair<unsigned, unsigned>, MCSymbol *> LocalSymbols;
  
      /// Keeps tracks of names that were used both for used declared and
      /// artificial symbols. The value is "true" if the name has been used for a
      /// non-section symbol (there can be at most one of those, plus an unlimited
      /// number of section symbols with the same name).
      StringMap<bool, BumpPtrAllocator &> UsedNames;
  
      /// The next ID to dole out to an unnamed assembler temporary symbol with
      /// a given prefix.
      StringMap<unsigned> NextID;
  
      /// Instances of directional local labels.
      DenseMap<unsigned, MCLabel *> Instances;
      /// NextInstance() creates the next instance of the directional local label
      /// for the LocalLabelVal and adds it to the map if needed.
      unsigned NextInstance(unsigned LocalLabelVal);
      /// GetInstance() gets the current instance of the directional local label
      /// for the LocalLabelVal and adds it to the map if needed.
      unsigned GetInstance(unsigned LocalLabelVal);
  
      /// The file name of the log file from the environment variable
      /// AS_SECURE_LOG_FILE.  Which must be set before the .secure_log_unique
      /// directive is used or it is an error.
      char *SecureLogFile;
      /// The stream that gets written to for the .secure_log_unique directive.
      std::unique_ptr<raw_fd_ostream> SecureLog;
      /// Boolean toggled when .secure_log_unique / .secure_log_reset is seen to
      /// catch errors if .secure_log_unique appears twice without
      /// .secure_log_reset appearing between them.
      bool SecureLogUsed = false;
  
      /// The compilation directory to use for DW_AT_comp_dir.
      SmallString<128> CompilationDir;
  
      /// The main file name if passed in explicitly.
      std::string MainFileName;
  
      /// The dwarf file and directory tables from the dwarf .file directive.
      /// We now emit a line table for each compile unit. To reduce the prologue
      /// size of each line table, the files and directories used by each compile
      /// unit are separated.
      std::map<unsigned, MCDwarfLineTable> MCDwarfLineTablesCUMap;
  
      /// The current dwarf line information from the last dwarf .loc directive.
      MCDwarfLoc CurrentDwarfLoc;
      bool DwarfLocSeen = false;
  
      /// Generate dwarf debugging info for assembly source files.
      bool GenDwarfForAssembly = false;
  
      /// The current dwarf file number when generate dwarf debugging info for
      /// assembly source files.
      unsigned GenDwarfFileNumber = 0;
  
      /// Sections for generating the .debug_ranges and .debug_aranges sections.
      SetVector<MCSection *> SectionsForRanges;
  
      /// The information gathered from labels that will have dwarf label
      /// entries when generating dwarf assembly source files.
      std::vector<MCGenDwarfLabelEntry> MCGenDwarfLabelEntries;
  
      /// The string to embed in the debug information for the compile unit, if
      /// non-empty.
      StringRef DwarfDebugFlags;
  
      /// The string to embed in as the dwarf AT_producer for the compile unit, if
      /// non-empty.
      StringRef DwarfDebugProducer;
  
      /// The maximum version of dwarf that we should emit.
      uint16_t DwarfVersion = 4;
  
      /// Honor temporary labels, this is useful for debugging semantic
      /// differences between temporary and non-temporary labels (primarily on
      /// Darwin).
      bool AllowTemporaryLabels = true;
      bool UseNamesOnTempLabels = true;
  
      /// The Compile Unit ID that we are currently processing.
      unsigned DwarfCompileUnitID = 0;
  
      struct ELFSectionKey {
        std::string SectionName;
        StringRef GroupName;
        unsigned UniqueID;
  
        ELFSectionKey(StringRef SectionName, StringRef GroupName,
                      unsigned UniqueID)
            : SectionName(SectionName), GroupName(GroupName), UniqueID(UniqueID) {
        }
  
        bool operator<(const ELFSectionKey &Other) const {
          if (SectionName != Other.SectionName)
            return SectionName < Other.SectionName;
          if (GroupName != Other.GroupName)
            return GroupName < Other.GroupName;
          return UniqueID < Other.UniqueID;
        }
      };
  
      struct COFFSectionKey {
        std::string SectionName;
        StringRef GroupName;
        int SelectionKey;
        unsigned UniqueID;
  
        COFFSectionKey(StringRef SectionName, StringRef GroupName,
                       int SelectionKey, unsigned UniqueID)
            : SectionName(SectionName), GroupName(GroupName),
              SelectionKey(SelectionKey), UniqueID(UniqueID) {}
  
        bool operator<(const COFFSectionKey &Other) const {
          if (SectionName != Other.SectionName)
            return SectionName < Other.SectionName;
          if (GroupName != Other.GroupName)
            return GroupName < Other.GroupName;
          if (SelectionKey != Other.SelectionKey)
            return SelectionKey < Other.SelectionKey;
          return UniqueID < Other.UniqueID;
        }
      };
  
      struct WasmSectionKey {
        std::string SectionName;
        StringRef GroupName;
        unsigned UniqueID;
  
        WasmSectionKey(StringRef SectionName, StringRef GroupName,
                       unsigned UniqueID)
            : SectionName(SectionName), GroupName(GroupName), UniqueID(UniqueID) {
        }
  
        bool operator<(const WasmSectionKey &Other) const {
          if (SectionName != Other.SectionName)
            return SectionName < Other.SectionName;
          if (GroupName != Other.GroupName)
            return GroupName < Other.GroupName;
          return UniqueID < Other.UniqueID;
        }
      };
  
      StringMap<MCSectionMachO *> MachOUniquingMap;
      std::map<ELFSectionKey, MCSectionELF *> ELFUniquingMap;
      std::map<COFFSectionKey, MCSectionCOFF *> COFFUniquingMap;
      std::map<WasmSectionKey, MCSectionWasm *> WasmUniquingMap;
      StringMap<bool> RelSecNames;
  
      SpecificBumpPtrAllocator<MCSubtargetInfo> MCSubtargetAllocator;
  
      /// Do automatic reset in destructor
      bool AutoReset;
  
      bool HadError = false;
  
      MCSymbol *createSymbolImpl(const StringMapEntry<bool> *Name,
                                 bool CanBeUnnamed);
      MCSymbol *createSymbol(StringRef Name, bool AlwaysAddSuffix,
                             bool IsTemporary);
  
      MCSymbol *getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
                                                  unsigned Instance);
  
      MCSectionELF *createELFSectionImpl(StringRef Section, unsigned Type,
                                         unsigned Flags, SectionKind K,
                                         unsigned EntrySize,
                                         const MCSymbolELF *Group,
                                         unsigned UniqueID,
                                         const MCSymbolELF *Associated);
  
      /// \brief Map of currently defined macros.
      StringMap<MCAsmMacro> MacroMap;
  
    public:
      explicit MCContext(const MCAsmInfo *MAI, const MCRegisterInfo *MRI,
                         const MCObjectFileInfo *MOFI,
                         const SourceMgr *Mgr = nullptr, bool DoAutoReset = true);
      MCContext(const MCContext &) = delete;
      MCContext &operator=(const MCContext &) = delete;
      ~MCContext();
  
      const SourceMgr *getSourceManager() const { return SrcMgr; }
  
      void setInlineSourceManager(SourceMgr *SM) { InlineSrcMgr = SM; }
  
      const MCAsmInfo *getAsmInfo() const { return MAI; }
  
      const MCRegisterInfo *getRegisterInfo() const { return MRI; }
  
      const MCObjectFileInfo *getObjectFileInfo() const { return MOFI; }
  
      CodeViewContext &getCVContext();
  
      void setAllowTemporaryLabels(bool Value) { AllowTemporaryLabels = Value; }
      void setUseNamesOnTempLabels(bool Value) { UseNamesOnTempLabels = Value; }
  
      /// \name Module Lifetime Management
      /// @{
  
      /// reset - return object to right after construction state to prepare
      /// to process a new module
      void reset();
  
      /// @}
  
      /// \name Symbol Management
      /// @{
  
      /// Create and return a new linker temporary symbol with a unique but
      /// unspecified name.
      MCSymbol *createLinkerPrivateTempSymbol();
  
      /// Create and return a new assembler temporary symbol with a unique but
      /// unspecified name.
      MCSymbol *createTempSymbol(bool CanBeUnnamed = true);
  
      MCSymbol *createTempSymbol(const Twine &Name, bool AlwaysAddSuffix,
                                 bool CanBeUnnamed = true);
  
      /// Create the definition of a directional local symbol for numbered label
      /// (used for "1:" definitions).
      MCSymbol *createDirectionalLocalSymbol(unsigned LocalLabelVal);
  
      /// Create and return a directional local symbol for numbered label (used
      /// for "1b" or 1f" references).
      MCSymbol *getDirectionalLocalSymbol(unsigned LocalLabelVal, bool Before);
  
      /// Lookup the symbol inside with the specified \p Name.  If it exists,
      /// return it.  If not, create a forward reference and return it.
      ///
      /// \param Name - The symbol name, which must be unique across all symbols.
      MCSymbol *getOrCreateSymbol(const Twine &Name);
  
      /// Gets a symbol that will be defined to the final stack offset of a local
      /// variable after codegen.
      ///
      /// \param Idx - The index of a local variable passed to @llvm.localescape.
      MCSymbol *getOrCreateFrameAllocSymbol(StringRef FuncName, unsigned Idx);
  
      MCSymbol *getOrCreateParentFrameOffsetSymbol(StringRef FuncName);
  
      MCSymbol *getOrCreateLSDASymbol(StringRef FuncName);
  
      /// Get the symbol for \p Name, or null.
      MCSymbol *lookupSymbol(const Twine &Name) const;
  
      /// Set value for a symbol.
      void setSymbolValue(MCStreamer &Streamer, StringRef Sym, uint64_t Val);
  
      /// getSymbols - Get a reference for the symbol table for clients that
      /// want to, for example, iterate over all symbols. 'const' because we
      /// still want any modifications to the table itself to use the MCContext
      /// APIs.
      const SymbolTable &getSymbols() const { return Symbols; }
  
      /// @}
  
      /// \name Section Management
      /// @{
  
      enum : unsigned {
        /// Pass this value as the UniqueID during section creation to get the
        /// generic section with the given name and characteristics. The usual
        /// sections such as .text use this ID.
        GenericSectionID = ~0U
      };
  
      /// Return the MCSection for the specified mach-o section.  This requires
      /// the operands to be valid.
      MCSectionMachO *getMachOSection(StringRef Segment, StringRef Section,
                                      unsigned TypeAndAttributes,
                                      unsigned Reserved2, SectionKind K,
                                      const char *BeginSymName = nullptr);
  
      MCSectionMachO *getMachOSection(StringRef Segment, StringRef Section,
                                      unsigned TypeAndAttributes, SectionKind K,
                                      const char *BeginSymName = nullptr) {
        return getMachOSection(Segment, Section, TypeAndAttributes, 0, K,
                               BeginSymName);
      }
  
      MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                  unsigned Flags) {
        return getELFSection(Section, Type, Flags, 0, "");
      }
  
      MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                  unsigned Flags, unsigned EntrySize,
                                  const Twine &Group) {
        return getELFSection(Section, Type, Flags, EntrySize, Group, ~0);
      }
  
      MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                  unsigned Flags, unsigned EntrySize,
                                  const Twine &Group, unsigned UniqueID) {
        return getELFSection(Section, Type, Flags, EntrySize, Group, UniqueID,
                             nullptr);
      }
  
      MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                  unsigned Flags, unsigned EntrySize,
                                  const Twine &Group, unsigned UniqueID,
                                  const MCSymbolELF *Associated);
  
      MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                                  unsigned Flags, unsigned EntrySize,
                                  const MCSymbolELF *Group, unsigned UniqueID,
                                  const MCSymbolELF *Associated);
  
      /// Get a section with the provided group identifier. This section is
      /// named by concatenating \p Prefix with '.' then \p Suffix. The \p Type
      /// describes the type of the section and \p Flags are used to further
      /// configure this named section.
      MCSectionELF *getELFNamedSection(const Twine &Prefix, const Twine &Suffix,
                                       unsigned Type, unsigned Flags,
                                       unsigned EntrySize = 0);
  
      MCSectionELF *createELFRelSection(const Twine &Name, unsigned Type,
                                        unsigned Flags, unsigned EntrySize,
                                        const MCSymbolELF *Group,
                                        const MCSectionELF *RelInfoSection);
  
      void renameELFSection(MCSectionELF *Section, StringRef Name);
  
      MCSectionELF *createELFGroupSection(const MCSymbolELF *Group);
  
      MCSectionCOFF *getCOFFSection(StringRef Section, unsigned Characteristics,
                                    SectionKind Kind, StringRef COMDATSymName,
                                    int Selection,
                                    unsigned UniqueID = GenericSectionID,
                                    const char *BeginSymName = nullptr);
  
      MCSectionCOFF *getCOFFSection(StringRef Section, unsigned Characteristics,
                                    SectionKind Kind,
                                    const char *BeginSymName = nullptr);
  
      MCSectionCOFF *getCOFFSection(StringRef Section);
  
      /// Gets or creates a section equivalent to Sec that is associated with the
      /// section containing KeySym. For example, to create a debug info section
      /// associated with an inline function, pass the normal debug info section
      /// as Sec and the function symbol as KeySym.
      MCSectionCOFF *
      getAssociativeCOFFSection(MCSectionCOFF *Sec, const MCSymbol *KeySym,
                                unsigned UniqueID = GenericSectionID);
  
      MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K) {
        return getWasmSection(Section, K, nullptr);
      }
  
      MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                    const char *BeginSymName) {
        return getWasmSection(Section, K, "", ~0, BeginSymName);
      }
  
      MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                    const Twine &Group, unsigned UniqueID) {
        return getWasmSection(Section, K, Group, UniqueID, nullptr);
      }
  
      MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                    const Twine &Group, unsigned UniqueID,
                                    const char *BeginSymName);
  
      MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                    const MCSymbolWasm *Group, unsigned UniqueID,
                                    const char *BeginSymName);
  
      // Create and save a copy of STI and return a reference to the copy.
      MCSubtargetInfo &getSubtargetCopy(const MCSubtargetInfo &STI);
  
      /// @}
  
      /// \name Dwarf Management
      /// @{
  
      /// \brief Get the compilation directory for DW_AT_comp_dir
      /// The compilation directory should be set with \c setCompilationDir before
      /// calling this function. If it is unset, an empty string will be returned.
      StringRef getCompilationDir() const { return CompilationDir; }
  
      /// \brief Set the compilation directory for DW_AT_comp_dir
      void setCompilationDir(StringRef S) { CompilationDir = S.str(); }
  
      /// \brief Get the main file name for use in error messages and debug
      /// info. This can be set to ensure we've got the correct file name
      /// after preprocessing or for -save-temps.
      const std::string &getMainFileName() const { return MainFileName; }
  
      /// \brief Set the main file name and override the default.
      void setMainFileName(StringRef S) { MainFileName = S; }
  
      /// Creates an entry in the dwarf file and directory tables.
      unsigned getDwarfFile(StringRef Directory, StringRef FileName,
                            unsigned FileNumber, unsigned CUID);
  
      bool isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID = 0);
  
      const std::map<unsigned, MCDwarfLineTable> &getMCDwarfLineTables() const {
        return MCDwarfLineTablesCUMap;
      }
  
      MCDwarfLineTable &getMCDwarfLineTable(unsigned CUID) {
        return MCDwarfLineTablesCUMap[CUID];
      }
  
      const MCDwarfLineTable &getMCDwarfLineTable(unsigned CUID) const {
        auto I = MCDwarfLineTablesCUMap.find(CUID);
        assert(I != MCDwarfLineTablesCUMap.end());
        return I->second;
      }
  
      const SmallVectorImpl<MCDwarfFile> &getMCDwarfFiles(unsigned CUID = 0) {
        return getMCDwarfLineTable(CUID).getMCDwarfFiles();
      }
  
      const SmallVectorImpl<std::string> &getMCDwarfDirs(unsigned CUID = 0) {
        return getMCDwarfLineTable(CUID).getMCDwarfDirs();
      }
  
      bool hasMCLineSections() const {
        for (const auto &Table : MCDwarfLineTablesCUMap)
          if (!Table.second.getMCDwarfFiles().empty() || Table.second.getLabel())
            return true;
        return false;
      }
  
      unsigned getDwarfCompileUnitID() { return DwarfCompileUnitID; }
  
      void setDwarfCompileUnitID(unsigned CUIndex) {
        DwarfCompileUnitID = CUIndex;
      }
  
      void setMCLineTableCompilationDir(unsigned CUID, StringRef CompilationDir) {
        getMCDwarfLineTable(CUID).setCompilationDir(CompilationDir);
      }
  
      /// Saves the information from the currently parsed dwarf .loc directive
      /// and sets DwarfLocSeen.  When the next instruction is assembled an entry
      /// in the line number table with this information and the address of the
      /// instruction will be created.
      void setCurrentDwarfLoc(unsigned FileNum, unsigned Line, unsigned Column,
                              unsigned Flags, unsigned Isa,
                              unsigned Discriminator) {
        CurrentDwarfLoc.setFileNum(FileNum);
        CurrentDwarfLoc.setLine(Line);
        CurrentDwarfLoc.setColumn(Column);
        CurrentDwarfLoc.setFlags(Flags);
        CurrentDwarfLoc.setIsa(Isa);
        CurrentDwarfLoc.setDiscriminator(Discriminator);
        DwarfLocSeen = true;
      }
  
      void clearDwarfLocSeen() { DwarfLocSeen = false; }
  
      bool getDwarfLocSeen() { return DwarfLocSeen; }
      const MCDwarfLoc &getCurrentDwarfLoc() { return CurrentDwarfLoc; }
  
      bool getGenDwarfForAssembly() { return GenDwarfForAssembly; }
      void setGenDwarfForAssembly(bool Value) { GenDwarfForAssembly = Value; }
      unsigned getGenDwarfFileNumber() { return GenDwarfFileNumber; }
  
      void setGenDwarfFileNumber(unsigned FileNumber) {
        GenDwarfFileNumber = FileNumber;
      }
  
      const SetVector<MCSection *> &getGenDwarfSectionSyms() {
        return SectionsForRanges;
      }
  
      bool addGenDwarfSection(MCSection *Sec) {
        return SectionsForRanges.insert(Sec);
      }
  
      void finalizeDwarfSections(MCStreamer &MCOS);
  
      const std::vector<MCGenDwarfLabelEntry> &getMCGenDwarfLabelEntries() const {
        return MCGenDwarfLabelEntries;
      }
  
      void addMCGenDwarfLabelEntry(const MCGenDwarfLabelEntry &E) {
        MCGenDwarfLabelEntries.push_back(E);
      }
  
      void setDwarfDebugFlags(StringRef S) { DwarfDebugFlags = S; }
      StringRef getDwarfDebugFlags() { return DwarfDebugFlags; }
  
      void setDwarfDebugProducer(StringRef S) { DwarfDebugProducer = S; }
      StringRef getDwarfDebugProducer() { return DwarfDebugProducer; }
  
      dwarf::DwarfFormat getDwarfFormat() const {
        // TODO: Support DWARF64
        return dwarf::DWARF32;
      }
  
      void setDwarfVersion(uint16_t v) { DwarfVersion = v; }
      uint16_t getDwarfVersion() const { return DwarfVersion; }
  
      /// @}
  
      char *getSecureLogFile() { return SecureLogFile; }
      raw_fd_ostream *getSecureLog() { return SecureLog.get(); }
  
      void setSecureLog(std::unique_ptr<raw_fd_ostream> Value) {
        SecureLog = std::move(Value);
      }
  
      bool getSecureLogUsed() { return SecureLogUsed; }
      void setSecureLogUsed(bool Value) { SecureLogUsed = Value; }
  
      void *allocate(unsigned Size, unsigned Align = 8) {
        return Allocator.Allocate(Size, Align);
      }
  
      void deallocate(void *Ptr) {}
  
      bool hadError() { return HadError; }
      void reportError(SMLoc L, const Twine &Msg);
      // Unrecoverable error has occurred. Display the best diagnostic we can
      // and bail via exit(1). For now, most MC backend errors are unrecoverable.
      // FIXME: We should really do something about that.
      LLVM_ATTRIBUTE_NORETURN void reportFatalError(SMLoc L,
                                                    const Twine &Msg);
  
      const MCAsmMacro *lookupMacro(StringRef Name) {
        StringMap<MCAsmMacro>::iterator I = MacroMap.find(Name);
        return (I == MacroMap.end()) ? nullptr : &I->getValue();
      }
  
      void defineMacro(StringRef Name, MCAsmMacro Macro) {
        MacroMap.insert(std::make_pair(Name, std::move(Macro)));
      }
  
      void undefineMacro(StringRef Name) { MacroMap.erase(Name); }
    };
  
  } // end namespace llvm
  
  // operator new and delete aren't allowed inside namespaces.
  // The throw specifications are mandated by the standard.
  /// \brief Placement new for using the MCContext's allocator.
  ///
  /// This placement form of operator new uses the MCContext's allocator for
  /// obtaining memory. It is a non-throwing new, which means that it returns
  /// null on error. (If that is what the allocator does. The current does, so if
  /// this ever changes, this operator will have to be changed, too.)
  /// Usage looks like this (assuming there's an MCContext 'Context' in scope):
  /// \code
  /// // Default alignment (8)
  /// IntegerLiteral *Ex = new (Context) IntegerLiteral(arguments);
  /// // Specific alignment
  /// IntegerLiteral *Ex2 = new (Context, 4) IntegerLiteral(arguments);
  /// \endcode
  /// Please note that you cannot use delete on the pointer; it must be
  /// deallocated using an explicit destructor call followed by
  /// \c Context.Deallocate(Ptr).
  ///
  /// \param Bytes The number of bytes to allocate. Calculated by the compiler.
  /// \param C The MCContext that provides the allocator.
  /// \param Alignment The alignment of the allocated memory (if the underlying
  ///                  allocator supports it).
  /// \return The allocated memory. Could be NULL.
  inline void *operator new(size_t Bytes, llvm::MCContext &C,
                            size_t Alignment = 8) noexcept {
    return C.allocate(Bytes, Alignment);
  }
  /// \brief Placement delete companion to the new above.
  ///
  /// This operator is just a companion to the new above. There is no way of
  /// invoking it directly; see the new operator for more details. This operator
  /// is called implicitly by the compiler if a placement new expression using
  /// the MCContext throws in the object constructor.
  inline void operator delete(void *Ptr, llvm::MCContext &C, size_t) noexcept {
    C.deallocate(Ptr);
  }
  
  /// This placement form of operator new[] uses the MCContext's allocator for
  /// obtaining memory. It is a non-throwing new[], which means that it returns
  /// null on error.
  /// Usage looks like this (assuming there's an MCContext 'Context' in scope):
  /// \code
  /// // Default alignment (8)
  /// char *data = new (Context) char[10];
  /// // Specific alignment
  /// char *data = new (Context, 4) char[10];
  /// \endcode
  /// Please note that you cannot use delete on the pointer; it must be
  /// deallocated using an explicit destructor call followed by
  /// \c Context.Deallocate(Ptr).
  ///
  /// \param Bytes The number of bytes to allocate. Calculated by the compiler.
  /// \param C The MCContext that provides the allocator.
  /// \param Alignment The alignment of the allocated memory (if the underlying
  ///                  allocator supports it).
  /// \return The allocated memory. Could be NULL.
  inline void *operator new[](size_t Bytes, llvm::MCContext &C,
                              size_t Alignment = 8) noexcept {
    return C.allocate(Bytes, Alignment);
  }
  
  /// \brief Placement delete[] companion to the new[] above.
  ///
  /// This operator is just a companion to the new[] above. There is no way of
  /// invoking it directly; see the new[] operator for more details. This operator
  /// is called implicitly by the compiler if a placement new[] expression using
  /// the MCContext throws in the object constructor.
  inline void operator delete[](void *Ptr, llvm::MCContext &C) noexcept {
    C.deallocate(Ptr);
  }
  
  #endif // LLVM_MC_MCCONTEXT_H
  