MCContext.h

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//===- MCContext.h - Machine Code Context -----------------------*- 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
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_MC_MCCONTEXT_H
#define LLVM_MC_MCCONTEXT_H
 
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/BinaryFormat/XCOFF.h"
#include "llvm/MC/MCAsmMacro.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCPseudoProbe.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>
 
namespace llvm {
 
class CodeViewContext;
class MCAsmInfo;
class MCInst;
class MCLabel;
class MCObjectFileInfo;
class MCRegisterInfo;
class MCSection;
class MCSectionCOFF;
class MCSectionDXContainer;
class MCSectionELF;
class MCSectionGOFF;
class MCSectionMachO;
class MCSectionSPIRV;
class MCSectionWasm;
class MCSectionXCOFF;
class MCStreamer;
class MCSubtargetInfo;
class MCSymbol;
class MCSymbolELF;
class MCSymbolWasm;
class MCSymbolXCOFF;
class MCTargetOptions;
class MDNode;
template <typename T> class SmallVectorImpl;
class SMDiagnostic;
class SMLoc;
class SourceMgr;
enum class EmitDwarfUnwindType;
 
/// Context object for machine code objects.  This class owns all of the
/// sections that it creates.
///
class MCContext {
public:
  using SymbolTable = StringMap<MCSymbol *, BumpPtrAllocator &>;
  using DiagHandlerTy =
      std::function<void(const SMDiagnostic &, bool, const SourceMgr &,
                         std::vector<const MDNode *> &)>;
  enum Environment {
    IsMachO,
    IsELF,
    IsGOFF,
    IsCOFF,
    IsSPIRV,
    IsWasm,
    IsXCOFF,
    IsDXContainer
  };
 
private:
  Environment Env;
 
  /// The name of the Segment where Swift5 Reflection Section data will be
  /// outputted
  StringRef Swift5ReflectionSegmentName;
 
  /// The triple for this object.
  Triple TT;
 
  /// The SourceMgr for this object, if any.
  const SourceMgr *SrcMgr;
 
  /// The SourceMgr for inline assembly, if any.
  std::unique_ptr<SourceMgr> InlineSrcMgr;
  std::vector<const MDNode *> LocInfos;
 
  DiagHandlerTy DiagHandler;
 
  /// The MCAsmInfo for this target.
  const MCAsmInfo *MAI;
 
  /// The MCRegisterInfo for this target.
  const MCRegisterInfo *MRI;
 
  /// The MCObjectFileInfo for this target.
  const MCObjectFileInfo *MOFI;
 
  /// The MCSubtargetInfo for this target.
  const MCSubtargetInfo *MSTI;
 
  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<MCSectionDXContainer> DXCAllocator;
  SpecificBumpPtrAllocator<MCSectionELF> ELFAllocator;
  SpecificBumpPtrAllocator<MCSectionMachO> MachOAllocator;
  SpecificBumpPtrAllocator<MCSectionGOFF> GOFFAllocator;
  SpecificBumpPtrAllocator<MCSectionSPIRV> SPIRVAllocator;
  SpecificBumpPtrAllocator<MCSectionWasm> WasmAllocator;
  SpecificBumpPtrAllocator<MCSectionXCOFF> XCOFFAllocator;
  SpecificBumpPtrAllocator<MCInst> MCInstAllocator;
 
  /// 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;
 
  /// Keeps track of labels that are used in inline assembly.
  SymbolTable InlineAsmUsedLabelNames;
 
  /// 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);
 
  /// LLVM_BB_ADDR_MAP version to emit.
  uint8_t BBAddrMapVersion = 1;
 
  /// 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;
 
  /// Prefix replacement map for source file information.
  std::map<std::string, const std::string, std::greater<std::string>>
      DebugPrefixMap;
 
  /// 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;
 
  /// The format of dwarf that we emit.
  dwarf::DwarfFormat DwarfFormat = dwarf::DWARF32;
 
  /// Honor temporary labels, this is useful for debugging semantic
  /// differences between temporary and non-temporary labels (primarily on
  /// Darwin).
  bool AllowTemporaryLabels = true;
  bool UseNamesOnTempLabels = false;
 
  /// The Compile Unit ID that we are currently processing.
  unsigned DwarfCompileUnitID = 0;
 
  /// A collection of MCPseudoProbe in the current module
  MCPseudoProbeTable PseudoProbeTable;
 
  // Sections are differentiated by the quadruple (section_name, group_name,
  // unique_id, link_to_symbol_name). Sections sharing the same quadruple are
  // combined into one section.
  struct ELFSectionKey {
    std::string SectionName;
    StringRef GroupName;
    StringRef LinkedToName;
    unsigned UniqueID;
 
    ELFSectionKey(StringRef SectionName, StringRef GroupName,
                  StringRef LinkedToName, unsigned UniqueID)
        : SectionName(SectionName), GroupName(GroupName),
          LinkedToName(LinkedToName), UniqueID(UniqueID) {}
 
    bool operator<(const ELFSectionKey &Other) const {
      if (SectionName != Other.SectionName)
        return SectionName < Other.SectionName;
      if (GroupName != Other.GroupName)
        return GroupName < Other.GroupName;
      if (int O = LinkedToName.compare(Other.LinkedToName))
        return O < 0;
      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;
    }
  };
 
  struct XCOFFSectionKey {
    // Section name.
    std::string SectionName;
    // Section property.
    // For csect section, it is storage mapping class.
    // For debug section, it is section type flags.
    union {
      XCOFF::StorageMappingClass MappingClass;
      XCOFF::DwarfSectionSubtypeFlags DwarfSubtypeFlags;
    };
    bool IsCsect;
 
    XCOFFSectionKey(StringRef SectionName,
                    XCOFF::StorageMappingClass MappingClass)
        : SectionName(SectionName), MappingClass(MappingClass), IsCsect(true) {}
 
    XCOFFSectionKey(StringRef SectionName,
                    XCOFF::DwarfSectionSubtypeFlags DwarfSubtypeFlags)
        : SectionName(SectionName), DwarfSubtypeFlags(DwarfSubtypeFlags),
          IsCsect(false) {}
 
    bool operator<(const XCOFFSectionKey &Other) const {
      if (IsCsect && Other.IsCsect)
        return std::tie(SectionName, MappingClass) <
               std::tie(Other.SectionName, Other.MappingClass);
      if (IsCsect != Other.IsCsect)
        return IsCsect;
      return std::tie(SectionName, DwarfSubtypeFlags) <
             std::tie(Other.SectionName, Other.DwarfSubtypeFlags);
    }
  };
 
  StringMap<MCSectionMachO *> MachOUniquingMap;
  std::map<ELFSectionKey, MCSectionELF *> ELFUniquingMap;
  std::map<COFFSectionKey, MCSectionCOFF *> COFFUniquingMap;
  std::map<std::string, MCSectionGOFF *> GOFFUniquingMap;
  std::map<WasmSectionKey, MCSectionWasm *> WasmUniquingMap;
  std::map<XCOFFSectionKey, MCSectionXCOFF *> XCOFFUniquingMap;
  StringMap<MCSectionDXContainer *> DXCUniquingMap;
  StringMap<bool> RelSecNames;
 
  SpecificBumpPtrAllocator<MCSubtargetInfo> MCSubtargetAllocator;
 
  /// Do automatic reset in destructor
  bool AutoReset;
 
  MCTargetOptions const *TargetOptions;
 
  bool HadError = false;
 
  void reportCommon(SMLoc Loc,
                    std::function<void(SMDiagnostic &, const SourceMgr *)>);
 
  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, bool IsComdat,
                                     unsigned UniqueID,
                                     const MCSymbolELF *LinkedToSym);
 
  MCSymbolXCOFF *createXCOFFSymbolImpl(const StringMapEntry<bool> *Name,
                                       bool IsTemporary);
 
  /// Map of currently defined macros.
  StringMap<MCAsmMacro> MacroMap;
 
  struct ELFEntrySizeKey {
    std::string SectionName;
    unsigned Flags;
    unsigned EntrySize;
 
    ELFEntrySizeKey(StringRef SectionName, unsigned Flags, unsigned EntrySize)
        : SectionName(SectionName), Flags(Flags), EntrySize(EntrySize) {}
 
    bool operator<(const ELFEntrySizeKey &Other) const {
      if (SectionName != Other.SectionName)
        return SectionName < Other.SectionName;
      if (Flags != Other.Flags)
        return Flags < Other.Flags;
      return EntrySize < Other.EntrySize;
    }
  };
 
  // Symbols must be assigned to a section with a compatible entry size and
  // flags. This map is used to assign unique IDs to sections to distinguish
  // between sections with identical names but incompatible entry sizes and/or
  // flags. This can occur when a symbol is explicitly assigned to a section,
  // e.g. via __attribute__((section("myname"))).
  std::map<ELFEntrySizeKey, unsigned> ELFEntrySizeMap;
 
  // This set is used to record the generic mergeable section names seen.
  // These are sections that are created as mergeable e.g. .debug_str. We need
  // to avoid assigning non-mergeable symbols to these sections. It is used
  // to prevent non-mergeable symbols being explicitly assigned  to mergeable
  // sections (e.g. via _attribute_((section("myname")))).
  DenseSet<StringRef> ELFSeenGenericMergeableSections;
 
public:
  explicit MCContext(const Triple &TheTriple, const MCAsmInfo *MAI,
                     const MCRegisterInfo *MRI, const MCSubtargetInfo *MSTI,
                     const SourceMgr *Mgr = nullptr,
                     MCTargetOptions const *TargetOpts = nullptr,
                     bool DoAutoReset = true,
                     StringRef Swift5ReflSegmentName = {});
  MCContext(const MCContext &) = delete;
  MCContext &operator=(const MCContext &) = delete;
  ~MCContext();
 
  Environment getObjectFileType() const { return Env; }
 
  const StringRef &getSwift5ReflectionSegmentName() const {
    return Swift5ReflectionSegmentName;
  }
  const Triple &getTargetTriple() const { return TT; }
  const SourceMgr *getSourceManager() const { return SrcMgr; }
 
  void initInlineSourceManager();
  SourceMgr *getInlineSourceManager() { return InlineSrcMgr.get(); }
  std::vector<const MDNode *> &getLocInfos() { return LocInfos; }
  void setDiagnosticHandler(DiagHandlerTy DiagHandler) {
    this->DiagHandler = DiagHandler;
  }
 
  void setObjectFileInfo(const MCObjectFileInfo *Mofi) { MOFI = Mofi; }
 
  const MCAsmInfo *getAsmInfo() const { return MAI; }
 
  const MCRegisterInfo *getRegisterInfo() const { return MRI; }
 
  const MCObjectFileInfo *getObjectFileInfo() const { return MOFI; }
 
  const MCSubtargetInfo *getSubtargetInfo() const { return MSTI; }
 
  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 McInst Management
 
  /// Create and return a new MC instruction.
  MCInst *createMCInst();
 
  /// \name Symbol Management
  /// @{
 
  /// Create and return a new linker temporary symbol with a unique but
  /// unspecified name.
  MCSymbol *createLinkerPrivateTempSymbol();
 
  /// Create a temporary symbol with a unique name. The name will be omitted
  /// in the symbol table if UseNamesOnTempLabels is false (default except
  /// MCAsmStreamer). The overload without Name uses an unspecified name.
  MCSymbol *createTempSymbol();
  MCSymbol *createTempSymbol(const Twine &Name, bool AlwaysAddSuffix = true);
 
  /// Create a temporary symbol with a unique name whose name cannot be
  /// omitted in the symbol table. This is rarely used.
  MCSymbol *createNamedTempSymbol();
  MCSymbol *createNamedTempSymbol(const Twine &Name);
 
  /// 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; }
 
  /// isInlineAsmLabel - Return true if the name is a label referenced in
  /// inline assembly.
  MCSymbol *getInlineAsmLabel(StringRef Name) const {
    return InlineAsmUsedLabelNames.lookup(Name);
  }
 
  /// registerInlineAsmLabel - Records that the name is a label referenced in
  /// inline assembly.
  void registerInlineAsmLabel(MCSymbol *Sym);
 
  /// @}
 
  /// \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, "", false);
  }
 
  MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                              unsigned Flags, unsigned EntrySize) {
    return getELFSection(Section, Type, Flags, EntrySize, "", false,
                         MCSection::NonUniqueID, nullptr);
  }
 
  MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                              unsigned Flags, unsigned EntrySize,
                              const Twine &Group, bool IsComdat) {
    return getELFSection(Section, Type, Flags, EntrySize, Group, IsComdat,
                         MCSection::NonUniqueID, nullptr);
  }
 
  MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                              unsigned Flags, unsigned EntrySize,
                              const Twine &Group, bool IsComdat,
                              unsigned UniqueID,
                              const MCSymbolELF *LinkedToSym);
 
  MCSectionELF *getELFSection(const Twine &Section, unsigned Type,
                              unsigned Flags, unsigned EntrySize,
                              const MCSymbolELF *Group, bool IsComdat,
                              unsigned UniqueID,
                              const MCSymbolELF *LinkedToSym);
 
  /// 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);
 
  MCSectionELF *createELFGroupSection(const MCSymbolELF *Group, bool IsComdat);
 
  void recordELFMergeableSectionInfo(StringRef SectionName, unsigned Flags,
                                     unsigned UniqueID, unsigned EntrySize);
 
  bool isELFImplicitMergeableSectionNamePrefix(StringRef Name);
 
  bool isELFGenericMergeableSection(StringRef Name);
 
  /// Return the unique ID of the section with the given name, flags and entry
  /// size, if it exists.
  Optional<unsigned> getELFUniqueIDForEntsize(StringRef SectionName,
                                              unsigned Flags,
                                              unsigned EntrySize);
 
  MCSectionGOFF *getGOFFSection(StringRef Section, SectionKind Kind,
                                MCSection *Parent, const MCExpr *SubsectionId);
 
  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);
 
  /// 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);
 
  MCSectionSPIRV *getSPIRVSection();
 
  MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                unsigned Flags = 0) {
    return getWasmSection(Section, K, Flags, nullptr);
  }
 
  MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                unsigned Flags, const char *BeginSymName) {
    return getWasmSection(Section, K, Flags, "", ~0, BeginSymName);
  }
 
  MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                unsigned Flags, const Twine &Group,
                                unsigned UniqueID) {
    return getWasmSection(Section, K, Flags, Group, UniqueID, nullptr);
  }
 
  MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                unsigned Flags, const Twine &Group,
                                unsigned UniqueID, const char *BeginSymName);
 
  MCSectionWasm *getWasmSection(const Twine &Section, SectionKind K,
                                unsigned Flags, const MCSymbolWasm *Group,
                                unsigned UniqueID, const char *BeginSymName);
  
  /// Get the section for the provided Section name
  MCSectionDXContainer *getDXContainerSection(StringRef Section, SectionKind K);
 
  bool hasXCOFFSection(StringRef Section,
                       XCOFF::CsectProperties CsectProp) const;
 
  MCSectionXCOFF *getXCOFFSection(
      StringRef Section, SectionKind K,
      Optional<XCOFF::CsectProperties> CsectProp = None,
      bool MultiSymbolsAllowed = false, const char *BeginSymName = nullptr,
      Optional<XCOFF::DwarfSectionSubtypeFlags> DwarfSubtypeFlags = None);
 
  // Create and save a copy of STI and return a reference to the copy.
  MCSubtargetInfo &getSubtargetCopy(const MCSubtargetInfo &STI);
 
  uint8_t getBBAddrMapVersion() const { return BBAddrMapVersion; }
 
  /// @}
 
  /// \name Dwarf Management
  /// @{
 
  /// 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; }
 
  /// Set the compilation directory for DW_AT_comp_dir
  void setCompilationDir(StringRef S) { CompilationDir = S.str(); }
 
  /// Add an entry to the debug prefix map.
  void addDebugPrefixMapEntry(const std::string &From, const std::string &To);
 
  /// Remap one path in-place as per the debug prefix map.
  void remapDebugPath(SmallVectorImpl<char> &Path);
 
  // Remaps all debug directory paths in-place as per the debug prefix map.
  void RemapDebugPaths();
 
  /// 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; }
 
  /// Set the main file name and override the default.
  void setMainFileName(StringRef S) { MainFileName = std::string(S); }
 
  /// Creates an entry in the dwarf file and directory tables.
  Expected<unsigned> getDwarfFile(StringRef Directory, StringRef FileName,
                                  unsigned FileNumber,
                                  Optional<MD5::MD5Result> Checksum,
                                  Optional<StringRef> Source, 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();
  }
 
  unsigned getDwarfCompileUnitID() { return DwarfCompileUnitID; }
 
  void setDwarfCompileUnitID(unsigned CUIndex) { DwarfCompileUnitID = CUIndex; }
 
  /// Specifies the "root" file and directory of the compilation unit.
  /// These are "file 0" and "directory 0" in DWARF v5.
  void setMCLineTableRootFile(unsigned CUID, StringRef CompilationDir,
                              StringRef Filename,
                              Optional<MD5::MD5Result> Checksum,
                              Optional<StringRef> Source) {
    getMCDwarfLineTable(CUID).setRootFile(CompilationDir, Filename, Checksum,
                                          Source);
  }
 
  /// Reports whether MD5 checksum usage is consistent (all-or-none).
  bool isDwarfMD5UsageConsistent(unsigned CUID) const {
    return getMCDwarfLineTable(CUID).isMD5UsageConsistent();
  }
 
  /// 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; }
  EmitDwarfUnwindType emitDwarfUnwindInfo() const;
 
  void setGenDwarfFileNumber(unsigned FileNumber) {
    GenDwarfFileNumber = FileNumber;
  }
 
  /// Specifies information about the "root file" for assembler clients
  /// (e.g., llvm-mc). Assumes compilation dir etc. have been set up.
  void setGenDwarfRootFile(StringRef FileName, StringRef Buffer);
 
  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; }
 
  void setDwarfFormat(dwarf::DwarfFormat f) { DwarfFormat = f; }
  dwarf::DwarfFormat getDwarfFormat() const { return DwarfFormat; }
 
  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 diagnose(const SMDiagnostic &SMD);
  void reportError(SMLoc L, const Twine &Msg);
  void reportWarning(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); }
 
  MCPseudoProbeTable &getMCPseudoProbeTable() { return PseudoProbeTable; }
};
 
} // end namespace llvm
 
// operator new and delete aren't allowed inside namespaces.
// The throw specifications are mandated by the standard.
/// 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);
}
/// 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);
}
 
/// 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