llvm-6502/include/llvm/IR/DebugInfoMetadata.h

//===- llvm/IR/DebugInfoMetadata.h - Debug info metadata --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Declarations for metadata specific to debug info.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_IR_DEBUGINFOMETADATA_H
#define LLVM_IR_DEBUGINFOMETADATA_H

#include "llvm/IR/Metadata.h"
#include "llvm/Support/Dwarf.h"

// Helper macros for defining get() overrides.
#define DEFINE_MDNODE_GET_UNPACK_IMPL(...) __VA_ARGS__
#define DEFINE_MDNODE_GET_UNPACK(ARGS) DEFINE_MDNODE_GET_UNPACK_IMPL ARGS
#define DEFINE_MDNODE_GET(CLASS, FORMAL, ARGS)                                 \
  static CLASS *get(LLVMContext &Context, DEFINE_MDNODE_GET_UNPACK(FORMAL)) {  \
    return getImpl(Context, DEFINE_MDNODE_GET_UNPACK(ARGS), Uniqued);          \
  }                                                                            \
  static CLASS *getIfExists(LLVMContext &Context,                              \
                            DEFINE_MDNODE_GET_UNPACK(FORMAL)) {                \
    return getImpl(Context, DEFINE_MDNODE_GET_UNPACK(ARGS), Uniqued,           \
                   /* ShouldCreate */ false);                                  \
  }                                                                            \
  static CLASS *getDistinct(LLVMContext &Context,                              \
                            DEFINE_MDNODE_GET_UNPACK(FORMAL)) {                \
    return getImpl(Context, DEFINE_MDNODE_GET_UNPACK(ARGS), Distinct);         \
  }                                                                            \
  static Temp##CLASS getTemporary(LLVMContext &Context,                        \
                                  DEFINE_MDNODE_GET_UNPACK(FORMAL)) {          \
    return Temp##CLASS(                                                        \
        getImpl(Context, DEFINE_MDNODE_GET_UNPACK(ARGS), Temporary));          \
  }

namespace llvm {

/// \brief Pointer union between a subclass of DebugNode and MDString.
///
/// \a MDCompositeType can be referenced via an \a MDString unique identifier.
/// This class allows some type safety in the face of that, requiring either a
/// node of a particular type or an \a MDString.
template <class T> class TypedDebugNodeRef {
  const Metadata *MD = nullptr;

public:
  TypedDebugNodeRef(std::nullptr_t) {}

  /// \brief Construct from a raw pointer.
  explicit TypedDebugNodeRef(const Metadata *MD) : MD(MD) {
    assert((!MD || isa<MDString>(MD) || isa<T>(MD)) && "Expected valid ref");
  }

  template <class U>
  TypedDebugNodeRef(
      const TypedDebugNodeRef<U> &X,
      typename std::enable_if<std::is_convertible<U *, T *>::value>::type * =
          nullptr)
      : MD(X) {}

  operator Metadata *() const { return const_cast<Metadata *>(MD); }

  bool operator==(const TypedDebugNodeRef<T> &X) const { return MD == X.MD; };
  bool operator!=(const TypedDebugNodeRef<T> &X) const { return MD != X.MD; };

  /// \brief Create a reference.
  ///
  /// Get a reference to \c N, using an \a MDString reference if available.
  static TypedDebugNodeRef get(const T *N);

  template <class MapTy> T *resolve(const MapTy &Map) const {
    if (auto *Typed = dyn_cast<T>(MD))
      return const_cast<T *>(Typed);

    auto *S = cast<MDString>(MD);
    auto I = Map.find(S);
    assert(I != Map.end() && "Missing identifier in type map");
    return cast<T>(I->second);
  }
};

typedef TypedDebugNodeRef<DebugNode> DebugNodeRef;
typedef TypedDebugNodeRef<MDScope> MDScopeRef;
typedef TypedDebugNodeRef<MDType> MDTypeRef;

class MDTypeRefArray {
  const MDTuple *N = nullptr;

public:
  MDTypeRefArray(const MDTuple *N) : N(N) {}
  operator MDTuple *() const { return const_cast<MDTuple *>(N); }
  MDTuple *operator->() const { return const_cast<MDTuple *>(N); }
  MDTuple &operator*() const { return *const_cast<MDTuple *>(N); }

  unsigned size() const { return N->getNumOperands(); }
  MDTypeRef operator[](unsigned I) const { return MDTypeRef(N->getOperand(I)); }

  class iterator : std::iterator<std::input_iterator_tag, MDTypeRef,
                                 std::ptrdiff_t, void, MDTypeRef> {
    MDNode::op_iterator I;

  public:
    explicit iterator(MDNode::op_iterator I) : I(I) {}
    MDTypeRef operator*() const { return MDTypeRef(*I); }
    iterator &operator++() {
      ++I;
      return *this;
    }
    iterator operator++(int) {
      iterator Temp(*this);
      ++I;
      return Temp;
    }
    bool operator==(const iterator &X) const { return I == X.I; }
    bool operator!=(const iterator &X) const { return I != X.I; }
  };

  iterator begin() const { return iterator(N->op_begin()); }
  iterator end() const { return iterator(N->op_end()); }
};

/// \brief Tagged DWARF-like metadata node.
///
/// A metadata node with a DWARF tag (i.e., a constant named \c DW_TAG_*,
/// defined in llvm/Support/Dwarf.h).  Called \a DebugNode because it's
/// potentially used for non-DWARF output.
class DebugNode : public MDNode {
  friend class LLVMContextImpl;
  friend class MDNode;

protected:
  DebugNode(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
            ArrayRef<Metadata *> Ops1, ArrayRef<Metadata *> Ops2 = None)
      : MDNode(C, ID, Storage, Ops1, Ops2) {
    assert(Tag < 1u << 16);
    SubclassData16 = Tag;
  }
  ~DebugNode() {}

  template <class Ty> Ty *getOperandAs(unsigned I) const {
    return cast_or_null<Ty>(getOperand(I));
  }

  StringRef getStringOperand(unsigned I) const {
    if (auto *S = getOperandAs<MDString>(I))
      return S->getString();
    return StringRef();
  }

  static MDString *getCanonicalMDString(LLVMContext &Context, StringRef S) {
    if (S.empty())
      return nullptr;
    return MDString::get(Context, S);
  }

public:
  unsigned getTag() const { return SubclassData16; }

  /// \brief Debug info flags.
  ///
  /// The three accessibility flags are mutually exclusive and rolled together
  /// in the first two bits.
  enum DIFlags {
#define HANDLE_DI_FLAG(ID, NAME) Flag##NAME = ID,
#include "llvm/IR/DebugInfoFlags.def"
    FlagAccessibility = FlagPrivate | FlagProtected | FlagPublic
  };

  DebugNodeRef getRef() const { return DebugNodeRef::get(this); }

  static bool classof(const Metadata *MD) {
    switch (MD->getMetadataID()) {
    default:
      return false;
    case GenericDebugNodeKind:
    case MDSubrangeKind:
    case MDEnumeratorKind:
    case MDBasicTypeKind:
    case MDDerivedTypeKind:
    case MDCompositeTypeKind:
    case MDSubroutineTypeKind:
    case MDFileKind:
    case MDCompileUnitKind:
    case MDSubprogramKind:
    case MDLexicalBlockKind:
    case MDLexicalBlockFileKind:
    case MDNamespaceKind:
    case MDTemplateTypeParameterKind:
    case MDTemplateValueParameterKind:
    case MDGlobalVariableKind:
    case MDLocalVariableKind:
    case MDObjCPropertyKind:
    case MDImportedEntityKind:
      return true;
    }
  }
};

template <class T>
struct simplify_type<const TypedDebugNodeRef<T>> {
  typedef Metadata *SimpleType;
  static SimpleType getSimplifiedValue(const TypedDebugNodeRef<T> &MD) {
    return MD;
  }
};

template <class T>
struct simplify_type<TypedDebugNodeRef<T>>
    : simplify_type<const TypedDebugNodeRef<T>> {};

/// \brief Generic tagged DWARF-like metadata node.
///
/// An un-specialized DWARF-like metadata node.  The first operand is a
/// (possibly empty) null-separated \a MDString header that contains arbitrary
/// fields.  The remaining operands are \a dwarf_operands(), and are pointers
/// to other metadata.
class GenericDebugNode : public DebugNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  GenericDebugNode(LLVMContext &C, StorageType Storage, unsigned Hash,
                   unsigned Tag, ArrayRef<Metadata *> Ops1,
                   ArrayRef<Metadata *> Ops2)
      : DebugNode(C, GenericDebugNodeKind, Storage, Tag, Ops1, Ops2) {
    setHash(Hash);
  }
  ~GenericDebugNode() { dropAllReferences(); }

  void setHash(unsigned Hash) { SubclassData32 = Hash; }
  void recalculateHash();

  static GenericDebugNode *getImpl(LLVMContext &Context, unsigned Tag,
                                   StringRef Header,
                                   ArrayRef<Metadata *> DwarfOps,
                                   StorageType Storage,
                                   bool ShouldCreate = true) {
    return getImpl(Context, Tag, getCanonicalMDString(Context, Header),
                   DwarfOps, Storage, ShouldCreate);
  }

  static GenericDebugNode *getImpl(LLVMContext &Context, unsigned Tag,
                                   MDString *Header,
                                   ArrayRef<Metadata *> DwarfOps,
                                   StorageType Storage,
                                   bool ShouldCreate = true);

  TempGenericDebugNode cloneImpl() const {
    return getTemporary(
        getContext(), getTag(), getHeader(),
        SmallVector<Metadata *, 4>(dwarf_op_begin(), dwarf_op_end()));
  }

public:
  unsigned getHash() const { return SubclassData32; }

  DEFINE_MDNODE_GET(GenericDebugNode, (unsigned Tag, StringRef Header,
                                       ArrayRef<Metadata *> DwarfOps),
                    (Tag, Header, DwarfOps))
  DEFINE_MDNODE_GET(GenericDebugNode, (unsigned Tag, MDString *Header,
                                       ArrayRef<Metadata *> DwarfOps),
                    (Tag, Header, DwarfOps))

  /// \brief Return a (temporary) clone of this.
  TempGenericDebugNode clone() const { return cloneImpl(); }

  unsigned getTag() const { return SubclassData16; }
  StringRef getHeader() const { return getStringOperand(0); }

  op_iterator dwarf_op_begin() const { return op_begin() + 1; }
  op_iterator dwarf_op_end() const { return op_end(); }
  op_range dwarf_operands() const {
    return op_range(dwarf_op_begin(), dwarf_op_end());
  }

  unsigned getNumDwarfOperands() const { return getNumOperands() - 1; }
  const MDOperand &getDwarfOperand(unsigned I) const {
    return getOperand(I + 1);
  }
  void replaceDwarfOperandWith(unsigned I, Metadata *New) {
    replaceOperandWith(I + 1, New);
  }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == GenericDebugNodeKind;
  }
};

/// \brief Array subrange.
///
/// TODO: Merge into node for DW_TAG_array_type, which should have a custom
/// type.
class MDSubrange : public DebugNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  int64_t Count;
  int64_t Lo;

  MDSubrange(LLVMContext &C, StorageType Storage, int64_t Count, int64_t Lo)
      : DebugNode(C, MDSubrangeKind, Storage, dwarf::DW_TAG_subrange_type,
                  None),
        Count(Count), Lo(Lo) {}
  ~MDSubrange() {}

  static MDSubrange *getImpl(LLVMContext &Context, int64_t Count, int64_t Lo,
                             StorageType Storage, bool ShouldCreate = true);

  TempMDSubrange cloneImpl() const {
    return getTemporary(getContext(), getCount(), getLo());
  }

public:
  DEFINE_MDNODE_GET(MDSubrange, (int64_t Count, int64_t Lo = 0), (Count, Lo))

  TempMDSubrange clone() const { return cloneImpl(); }

  int64_t getLo() const { return Lo; }
  int64_t getCount() const { return Count; }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDSubrangeKind;
  }
};

/// \brief Enumeration value.
///
/// TODO: Add a pointer to the context (DW_TAG_enumeration_type) once that no
/// longer creates a type cycle.
class MDEnumerator : public DebugNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  int64_t Value;

  MDEnumerator(LLVMContext &C, StorageType Storage, int64_t Value,
               ArrayRef<Metadata *> Ops)
      : DebugNode(C, MDEnumeratorKind, Storage, dwarf::DW_TAG_enumerator, Ops),
        Value(Value) {}
  ~MDEnumerator() {}

  static MDEnumerator *getImpl(LLVMContext &Context, int64_t Value,
                               StringRef Name, StorageType Storage,
                               bool ShouldCreate = true) {
    return getImpl(Context, Value, getCanonicalMDString(Context, Name), Storage,
                   ShouldCreate);
  }
  static MDEnumerator *getImpl(LLVMContext &Context, int64_t Value,
                               MDString *Name, StorageType Storage,
                               bool ShouldCreate = true);

  TempMDEnumerator cloneImpl() const {
    return getTemporary(getContext(), getValue(), getName());
  }

public:
  DEFINE_MDNODE_GET(MDEnumerator, (int64_t Value, StringRef Name),
                    (Value, Name))
  DEFINE_MDNODE_GET(MDEnumerator, (int64_t Value, MDString *Name),
                    (Value, Name))

  TempMDEnumerator clone() const { return cloneImpl(); }

  int64_t getValue() const { return Value; }
  StringRef getName() const { return getStringOperand(0); }

  MDString *getRawName() const { return getOperandAs<MDString>(0); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDEnumeratorKind;
  }
};

/// \brief Base class for scope-like contexts.
///
/// Base class for lexical scopes and types (which are also declaration
/// contexts).
///
/// TODO: Separate the concepts of declaration contexts and lexical scopes.
class MDScope : public DebugNode {
protected:
  MDScope(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
          ArrayRef<Metadata *> Ops)
      : DebugNode(C, ID, Storage, Tag, Ops) {}
  ~MDScope() {}

public:
  MDFile *getFile() const { return cast_or_null<MDFile>(getRawFile()); }

  /// \brief Return the raw underlying file.
  ///
  /// An \a MDFile is an \a MDScope, but it doesn't point at a separate file
  /// (it\em is the file).  If \c this is an \a MDFile, we need to return \c
  /// this.  Otherwise, return the first operand, which is where all other
  /// subclasses store their file pointer.
  Metadata *getRawFile() const {
    return isa<MDFile>(this) ? const_cast<MDScope *>(this)
                             : static_cast<Metadata *>(getOperand(0));
  }

  MDScopeRef getRef() const { return MDScopeRef::get(this); }

  static bool classof(const Metadata *MD) {
    switch (MD->getMetadataID()) {
    default:
      return false;
    case MDBasicTypeKind:
    case MDDerivedTypeKind:
    case MDCompositeTypeKind:
    case MDSubroutineTypeKind:
    case MDFileKind:
    case MDCompileUnitKind:
    case MDSubprogramKind:
    case MDLexicalBlockKind:
    case MDLexicalBlockFileKind:
    case MDNamespaceKind:
      return true;
    }
  }
};

/// \brief File.
///
/// TODO: Merge with directory/file node (including users).
/// TODO: Canonicalize paths on creation.
class MDFile : public MDScope {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDFile(LLVMContext &C, StorageType Storage, ArrayRef<Metadata *> Ops)
      : MDScope(C, MDFileKind, Storage, dwarf::DW_TAG_file_type, Ops) {}
  ~MDFile() {}

  static MDFile *getImpl(LLVMContext &Context, StringRef Filename,
                         StringRef Directory, StorageType Storage,
                         bool ShouldCreate = true) {
    return getImpl(Context, getCanonicalMDString(Context, Filename),
                   getCanonicalMDString(Context, Directory), Storage,
                   ShouldCreate);
  }
  static MDFile *getImpl(LLVMContext &Context, MDString *Filename,
                         MDString *Directory, StorageType Storage,
                         bool ShouldCreate = true);

  TempMDFile cloneImpl() const {
    return getTemporary(getContext(), getFilename(), getDirectory());
  }

public:
  DEFINE_MDNODE_GET(MDFile, (StringRef Filename, StringRef Directory),
                    (Filename, Directory))
  DEFINE_MDNODE_GET(MDFile, (MDString * Filename, MDString *Directory),
                    (Filename, Directory))

  TempMDFile clone() const { return cloneImpl(); }

  StringRef getFilename() const { return getStringOperand(0); }
  StringRef getDirectory() const { return getStringOperand(1); }

  MDString *getRawFilename() const { return getOperandAs<MDString>(0); }
  MDString *getRawDirectory() const { return getOperandAs<MDString>(1); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDFileKind;
  }
};

/// \brief Base class for types.
///
/// TODO: Remove the hardcoded name and context, since many types don't use
/// them.
/// TODO: Split up flags.
class MDType : public MDScope {
  unsigned Line;
  unsigned Flags;
  uint64_t SizeInBits;
  uint64_t AlignInBits;
  uint64_t OffsetInBits;

protected:
  MDType(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
         unsigned Line, uint64_t SizeInBits, uint64_t AlignInBits,
         uint64_t OffsetInBits, unsigned Flags, ArrayRef<Metadata *> Ops)
      : MDScope(C, ID, Storage, Tag, Ops), Line(Line), Flags(Flags),
        SizeInBits(SizeInBits), AlignInBits(AlignInBits),
        OffsetInBits(OffsetInBits) {}
  ~MDType() {}

public:
  TempMDType clone() const {
    return TempMDType(cast<MDType>(MDNode::clone().release()));
  }

  unsigned getLine() const { return Line; }
  uint64_t getSizeInBits() const { return SizeInBits; }
  uint64_t getAlignInBits() const { return AlignInBits; }
  uint64_t getOffsetInBits() const { return OffsetInBits; }
  unsigned getFlags() const { return Flags; }

  MDScopeRef getScope() const { return MDScopeRef(getRawScope()); }
  StringRef getName() const { return getStringOperand(2); }


  Metadata *getRawScope() const { return getOperand(1); }
  MDString *getRawName() const { return getOperandAs<MDString>(2); }

  void setFlags(unsigned NewFlags) {
    assert(!isUniqued() && "Cannot set flags on uniqued nodes");
    Flags = NewFlags;
  }

  MDTypeRef getRef() const { return MDTypeRef::get(this); }

  static bool classof(const Metadata *MD) {
    switch (MD->getMetadataID()) {
    default:
      return false;
    case MDBasicTypeKind:
    case MDDerivedTypeKind:
    case MDCompositeTypeKind:
    case MDSubroutineTypeKind:
      return true;
    }
  }
};

/// \brief Basic type.
///
/// TODO: Split out DW_TAG_unspecified_type.
/// TODO: Drop unused accessors.
class MDBasicType : public MDType {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Encoding;

  MDBasicType(LLVMContext &C, StorageType Storage, unsigned Tag,
              uint64_t SizeInBits, uint64_t AlignInBits, unsigned Encoding,
              ArrayRef<Metadata *> Ops)
      : MDType(C, MDBasicTypeKind, Storage, Tag, 0, SizeInBits, AlignInBits, 0,
               0, Ops),
        Encoding(Encoding) {}
  ~MDBasicType() {}

  static MDBasicType *getImpl(LLVMContext &Context, unsigned Tag,
                              StringRef Name, uint64_t SizeInBits,
                              uint64_t AlignInBits, unsigned Encoding,
                              StorageType Storage, bool ShouldCreate = true) {
    return getImpl(Context, Tag, getCanonicalMDString(Context, Name),
                   SizeInBits, AlignInBits, Encoding, Storage, ShouldCreate);
  }
  static MDBasicType *getImpl(LLVMContext &Context, unsigned Tag,
                              MDString *Name, uint64_t SizeInBits,
                              uint64_t AlignInBits, unsigned Encoding,
                              StorageType Storage, bool ShouldCreate = true);

  TempMDBasicType cloneImpl() const {
    return getTemporary(getContext(), getTag(), getName(), getSizeInBits(),
                        getAlignInBits(), getEncoding());
  }

public:
  DEFINE_MDNODE_GET(MDBasicType, (unsigned Tag, StringRef Name),
                    (Tag, Name, 0, 0, 0))
  DEFINE_MDNODE_GET(MDBasicType,
                    (unsigned Tag, StringRef Name, uint64_t SizeInBits,
                     uint64_t AlignInBits, unsigned Encoding),
                    (Tag, Name, SizeInBits, AlignInBits, Encoding))
  DEFINE_MDNODE_GET(MDBasicType,
                    (unsigned Tag, MDString *Name, uint64_t SizeInBits,
                     uint64_t AlignInBits, unsigned Encoding),
                    (Tag, Name, SizeInBits, AlignInBits, Encoding))

  TempMDBasicType clone() const { return cloneImpl(); }

  unsigned getEncoding() const { return Encoding; }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDBasicTypeKind;
  }
};

/// \brief Base class for MDDerivedType and MDCompositeType.
///
/// TODO: Delete; they're not really related.
class MDDerivedTypeBase : public MDType {
protected:
  MDDerivedTypeBase(LLVMContext &C, unsigned ID, StorageType Storage,
                    unsigned Tag, unsigned Line, uint64_t SizeInBits,
                    uint64_t AlignInBits, uint64_t OffsetInBits, unsigned Flags,
                    ArrayRef<Metadata *> Ops)
      : MDType(C, ID, Storage, Tag, Line, SizeInBits, AlignInBits, OffsetInBits,
               Flags, Ops) {}
  ~MDDerivedTypeBase() {}

public:
  MDTypeRef getBaseType() const { return MDTypeRef(getRawBaseType()); }
  Metadata *getRawBaseType() const { return getOperand(3); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDDerivedTypeKind ||
           MD->getMetadataID() == MDCompositeTypeKind ||
           MD->getMetadataID() == MDSubroutineTypeKind;
  }
};

/// \brief Derived types.
///
/// This includes qualified types, pointers, references, friends, typedefs, and
/// class members.
///
/// TODO: Split out members (inheritance, fields, methods, etc.).
class MDDerivedType : public MDDerivedTypeBase {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDDerivedType(LLVMContext &C, StorageType Storage, unsigned Tag,
                unsigned Line, uint64_t SizeInBits, uint64_t AlignInBits,
                uint64_t OffsetInBits, unsigned Flags, ArrayRef<Metadata *> Ops)
      : MDDerivedTypeBase(C, MDDerivedTypeKind, Storage, Tag, Line, SizeInBits,
                          AlignInBits, OffsetInBits, Flags, Ops) {}
  ~MDDerivedType() {}

  static MDDerivedType *getImpl(LLVMContext &Context, unsigned Tag,
                                StringRef Name, MDFile *File, unsigned Line,
                                MDScopeRef Scope, MDTypeRef BaseType,
                                uint64_t SizeInBits, uint64_t AlignInBits,
                                uint64_t OffsetInBits, unsigned Flags,
                                Metadata *ExtraData, StorageType Storage,
                                bool ShouldCreate = true) {
    return getImpl(Context, Tag, getCanonicalMDString(Context, Name), File,
                   Line, Scope, BaseType, SizeInBits, AlignInBits, OffsetInBits,
                   Flags, ExtraData, Storage, ShouldCreate);
  }
  static MDDerivedType *getImpl(LLVMContext &Context, unsigned Tag,
                                MDString *Name, Metadata *File, unsigned Line,
                                Metadata *Scope, Metadata *BaseType,
                                uint64_t SizeInBits, uint64_t AlignInBits,
                                uint64_t OffsetInBits, unsigned Flags,
                                Metadata *ExtraData, StorageType Storage,
                                bool ShouldCreate = true);

  TempMDDerivedType cloneImpl() const {
    return getTemporary(getContext(), getTag(), getName(), getFile(), getLine(),
                        getScope(), getBaseType(), getSizeInBits(),
                        getAlignInBits(), getOffsetInBits(), getFlags(),
                        getExtraData());
  }

public:
  DEFINE_MDNODE_GET(MDDerivedType,
                    (unsigned Tag, MDString *Name, Metadata *File,
                     unsigned Line, Metadata *Scope, Metadata *BaseType,
                     uint64_t SizeInBits, uint64_t AlignInBits,
                     uint64_t OffsetInBits, unsigned Flags,
                     Metadata *ExtraData = nullptr),
                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
                     AlignInBits, OffsetInBits, Flags, ExtraData))
  DEFINE_MDNODE_GET(MDDerivedType,
                    (unsigned Tag, StringRef Name, MDFile *File, unsigned Line,
                     MDScopeRef Scope, MDTypeRef BaseType, uint64_t SizeInBits,
                     uint64_t AlignInBits, uint64_t OffsetInBits,
                     unsigned Flags, Metadata *ExtraData = nullptr),
                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
                     AlignInBits, OffsetInBits, Flags, ExtraData))

  TempMDDerivedType clone() const { return cloneImpl(); }

  /// \brief Get extra data associated with this derived type.
  ///
  /// Class type for pointer-to-members, objective-c property node for ivars,
  /// or global constant wrapper for static members.
  ///
  /// TODO: Separate out types that need this extra operand: pointer-to-member
  /// types and member fields (static members and ivars).
  Metadata *getExtraData() const { return getRawExtraData(); }
  Metadata *getRawExtraData() const { return getOperand(4); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDDerivedTypeKind;
  }
};

/// \brief Base class for MDCompositeType and MDSubroutineType.
///
/// TODO: Delete; they're not really related.
class MDCompositeTypeBase : public MDDerivedTypeBase {
  unsigned RuntimeLang;

protected:
  MDCompositeTypeBase(LLVMContext &C, unsigned ID, StorageType Storage,
                      unsigned Tag, unsigned Line, unsigned RuntimeLang,
                      uint64_t SizeInBits, uint64_t AlignInBits,
                      uint64_t OffsetInBits, unsigned Flags,
                      ArrayRef<Metadata *> Ops)
      : MDDerivedTypeBase(C, ID, Storage, Tag, Line, SizeInBits, AlignInBits,
                          OffsetInBits, Flags, Ops),
        RuntimeLang(RuntimeLang) {}
  ~MDCompositeTypeBase() {}

public:
  MDTuple *getElements() const {
    return cast_or_null<MDTuple>(getRawElements());
  }
  MDTypeRef getVTableHolder() const { return MDTypeRef(getRawVTableHolder()); }
  MDTemplateParameterArray getTemplateParams() const {
    return cast_or_null<MDTuple>(getRawTemplateParams());
  }
  StringRef getIdentifier() const { return getStringOperand(7); }
  unsigned getRuntimeLang() const { return RuntimeLang; }

  Metadata *getRawElements() const { return getOperand(4); }
  Metadata *getRawVTableHolder() const { return getOperand(5); }
  Metadata *getRawTemplateParams() const { return getOperand(6); }
  MDString *getRawIdentifier() const { return getOperandAs<MDString>(7); }

  /// \brief Replace operands.
  ///
  /// If this \a isUniqued() and not \a isResolved(), on a uniquing collision
  /// this will be RAUW'ed and deleted.  Use a \a TrackingMDRef to keep track
  /// of its movement if necessary.
  /// @{
  void replaceElements(MDTuple *Elements) {
#ifndef NDEBUG
    if (auto *Old = cast_or_null<MDTuple>(getElements()))
      for (const auto &Op : Old->operands())
        assert(std::find(Elements->op_begin(), Elements->op_end(), Op) &&
               "Lost a member during member list replacement");
#endif
    replaceOperandWith(4, Elements);
  }
  void replaceVTableHolder(MDTypeRef VTableHolder) {
    replaceOperandWith(5, VTableHolder);
  }
  void replaceTemplateParams(MDTemplateParameterArray TemplateParams) {
    replaceOperandWith(6, TemplateParams);
  }
  /// @}

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDCompositeTypeKind ||
           MD->getMetadataID() == MDSubroutineTypeKind;
  }
};

/// \brief Composite types.
///
/// TODO: Detach from DerivedTypeBase (split out MDEnumType?).
/// TODO: Create a custom, unrelated node for DW_TAG_array_type.
class MDCompositeType : public MDCompositeTypeBase {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDCompositeType(LLVMContext &C, StorageType Storage, unsigned Tag,
                  unsigned Line, unsigned RuntimeLang, uint64_t SizeInBits,
                  uint64_t AlignInBits, uint64_t OffsetInBits, unsigned Flags,
                  ArrayRef<Metadata *> Ops)
      : MDCompositeTypeBase(C, MDCompositeTypeKind, Storage, Tag, Line,
                            RuntimeLang, SizeInBits, AlignInBits, OffsetInBits,
                            Flags, Ops) {}
  ~MDCompositeType() {}

  static MDCompositeType *
  getImpl(LLVMContext &Context, unsigned Tag, StringRef Name, Metadata *File,
          unsigned Line, MDScopeRef Scope, MDTypeRef BaseType,
          uint64_t SizeInBits, uint64_t AlignInBits, uint64_t OffsetInBits,
          uint64_t Flags, MDTuple *Elements, unsigned RuntimeLang,
          MDTypeRef VTableHolder, MDTemplateParameterArray TemplateParams,
          StringRef Identifier, StorageType Storage, bool ShouldCreate = true) {
    return getImpl(Context, Tag, getCanonicalMDString(Context, Name), File,
                   Line, Scope, BaseType, SizeInBits, AlignInBits, OffsetInBits,
                   Flags, Elements, RuntimeLang, VTableHolder, TemplateParams,
                   getCanonicalMDString(Context, Identifier), Storage,
                   ShouldCreate);
  }
  static MDCompositeType *
  getImpl(LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
          unsigned Line, Metadata *Scope, Metadata *BaseType,
          uint64_t SizeInBits, uint64_t AlignInBits, uint64_t OffsetInBits,
          unsigned Flags, Metadata *Elements, unsigned RuntimeLang,
          Metadata *VTableHolder, Metadata *TemplateParams,
          MDString *Identifier, StorageType Storage, bool ShouldCreate = true);

  TempMDCompositeType cloneImpl() const {
    return getTemporary(getContext(), getTag(), getName(), getFile(), getLine(),
                        getScope(), getBaseType(), getSizeInBits(),
                        getAlignInBits(), getOffsetInBits(), getFlags(),
                        getElements(), getRuntimeLang(), getVTableHolder(),
                        getTemplateParams(), getIdentifier());
  }

public:
  DEFINE_MDNODE_GET(MDCompositeType,
                    (unsigned Tag, StringRef Name, MDFile *File, unsigned Line,
                     MDScopeRef Scope, MDTypeRef BaseType, uint64_t SizeInBits,
                     uint64_t AlignInBits, uint64_t OffsetInBits,
                     unsigned Flags, MDTuple *Elements, unsigned RuntimeLang,
                     MDTypeRef VTableHolder,
                     MDTemplateParameterArray TemplateParams = nullptr,
                     StringRef Identifier = ""),
                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
                     AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
                     VTableHolder, TemplateParams, Identifier))
  DEFINE_MDNODE_GET(MDCompositeType,
                    (unsigned Tag, MDString *Name, Metadata *File,
                     unsigned Line, Metadata *Scope, Metadata *BaseType,
                     uint64_t SizeInBits, uint64_t AlignInBits,
                     uint64_t OffsetInBits, unsigned Flags, Metadata *Elements,
                     unsigned RuntimeLang, Metadata *VTableHolder,
                     Metadata *TemplateParams = nullptr,
                     MDString *Identifier = nullptr),
                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
                     AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
                     VTableHolder, TemplateParams, Identifier))

  TempMDCompositeType clone() const { return cloneImpl(); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDCompositeTypeKind;
  }
};

template <class T> TypedDebugNodeRef<T> TypedDebugNodeRef<T>::get(const T *N) {
  if (N)
    if (auto *Composite = dyn_cast<MDCompositeType>(N))
      if (auto *S = Composite->getRawIdentifier())
        return TypedDebugNodeRef<T>(S);
  return TypedDebugNodeRef<T>(N);
}

/// \brief Type array for a subprogram.
///
/// TODO: Detach from CompositeType, and fold the array of types in directly
/// as operands.
class MDSubroutineType : public MDCompositeTypeBase {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDSubroutineType(LLVMContext &C, StorageType Storage, unsigned Flags,
                   ArrayRef<Metadata *> Ops)
      : MDCompositeTypeBase(C, MDSubroutineTypeKind, Storage,
                            dwarf::DW_TAG_subroutine_type, 0, 0, 0, 0, 0, Flags,
                            Ops) {}
  ~MDSubroutineType() {}

  static MDSubroutineType *getImpl(LLVMContext &Context, unsigned Flags,
                                   Metadata *TypeArray, StorageType Storage,
                                   bool ShouldCreate = true);

  TempMDSubroutineType cloneImpl() const {
    return getTemporary(getContext(), getFlags(), getTypeArray());
  }

public:
  DEFINE_MDNODE_GET(MDSubroutineType, (unsigned Flags, Metadata *TypeArray),
                    (Flags, TypeArray))

  TempMDSubroutineType clone() const { return cloneImpl(); }

  MDTypeRefArray getTypeArray() const { return getElements(); }
  Metadata *getRawTypeArray() const { return getRawElements(); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDSubroutineTypeKind;
  }
};

/// \brief Compile unit.
class MDCompileUnit : public MDScope {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned SourceLanguage;
  bool IsOptimized;
  unsigned RuntimeVersion;
  unsigned EmissionKind;

  MDCompileUnit(LLVMContext &C, StorageType Storage, unsigned SourceLanguage,
                bool IsOptimized, unsigned RuntimeVersion,
                unsigned EmissionKind, ArrayRef<Metadata *> Ops)
      : MDScope(C, MDCompileUnitKind, Storage, dwarf::DW_TAG_compile_unit, Ops),
        SourceLanguage(SourceLanguage), IsOptimized(IsOptimized),
        RuntimeVersion(RuntimeVersion), EmissionKind(EmissionKind) {}
  ~MDCompileUnit() {}

  static MDCompileUnit *
  getImpl(LLVMContext &Context, unsigned SourceLanguage, MDFile *File,
          StringRef Producer, bool IsOptimized, StringRef Flags,
          unsigned RuntimeVersion, StringRef SplitDebugFilename,
          unsigned EmissionKind, MDTuple *EnumTypes, MDTuple *RetainedTypes,
          MDTuple *Subprograms, MDTuple *GlobalVariables,
          MDTuple *ImportedEntities, StorageType Storage,
          bool ShouldCreate = true) {
    return getImpl(Context, SourceLanguage, File,
                   getCanonicalMDString(Context, Producer), IsOptimized,
                   getCanonicalMDString(Context, Flags), RuntimeVersion,
                   getCanonicalMDString(Context, SplitDebugFilename),
                   EmissionKind, EnumTypes, RetainedTypes, Subprograms,
                   GlobalVariables, ImportedEntities, Storage, ShouldCreate);
  }
  static MDCompileUnit *
  getImpl(LLVMContext &Context, unsigned SourceLanguage, Metadata *File,
          MDString *Producer, bool IsOptimized, MDString *Flags,
          unsigned RuntimeVersion, MDString *SplitDebugFilename,
          unsigned EmissionKind, Metadata *EnumTypes, Metadata *RetainedTypes,
          Metadata *Subprograms, Metadata *GlobalVariables,
          Metadata *ImportedEntities, StorageType Storage,
          bool ShouldCreate = true);

  TempMDCompileUnit cloneImpl() const {
    return getTemporary(
        getContext(), getSourceLanguage(), getFile(), getProducer(),
        isOptimized(), getFlags(), getRuntimeVersion(), getSplitDebugFilename(),
        getEmissionKind(), getEnumTypes(), getRetainedTypes(), getSubprograms(),
        getGlobalVariables(), getImportedEntities());
  }

public:
  DEFINE_MDNODE_GET(MDCompileUnit,
                    (unsigned SourceLanguage, MDFile *File, StringRef Producer,
                     bool IsOptimized, StringRef Flags, unsigned RuntimeVersion,
                     StringRef SplitDebugFilename, unsigned EmissionKind,
                     MDTuple *EnumTypes, MDTuple *RetainedTypes,
                     MDTuple *Subprograms, MDTuple *GlobalVariables,
                     MDTuple *ImportedEntities),
                    (SourceLanguage, File, Producer, IsOptimized, Flags,
                     RuntimeVersion, SplitDebugFilename, EmissionKind,
                     EnumTypes, RetainedTypes, Subprograms, GlobalVariables,
                     ImportedEntities))
  DEFINE_MDNODE_GET(MDCompileUnit,
                    (unsigned SourceLanguage, Metadata *File,
                     MDString *Producer, bool IsOptimized, MDString *Flags,
                     unsigned RuntimeVersion, MDString *SplitDebugFilename,
                     unsigned EmissionKind, Metadata *EnumTypes,
                     Metadata *RetainedTypes, Metadata *Subprograms,
                     Metadata *GlobalVariables, Metadata *ImportedEntities),
                    (SourceLanguage, File, Producer, IsOptimized, Flags,
                     RuntimeVersion, SplitDebugFilename, EmissionKind,
                     EnumTypes, RetainedTypes, Subprograms, GlobalVariables,
                     ImportedEntities))

  TempMDCompileUnit clone() const { return cloneImpl(); }

  unsigned getSourceLanguage() const { return SourceLanguage; }
  bool isOptimized() const { return IsOptimized; }
  unsigned getRuntimeVersion() const { return RuntimeVersion; }
  unsigned getEmissionKind() const { return EmissionKind; }
  StringRef getProducer() const { return getStringOperand(1); }
  StringRef getFlags() const { return getStringOperand(2); }
  StringRef getSplitDebugFilename() const { return getStringOperand(3); }
  MDCompositeTypeArray getEnumTypes() const {
    return cast_or_null<MDTuple>(getRawEnumTypes());
  }
  MDTypeArray getRetainedTypes() const {
    return cast_or_null<MDTuple>(getRawRetainedTypes());
  }
  MDSubprogramArray getSubprograms() const {
    return cast_or_null<MDTuple>(getRawSubprograms());
  }
  MDGlobalVariableArray getGlobalVariables() const {
    return cast_or_null<MDTuple>(getRawGlobalVariables());
  }
  MDImportedEntityArray getImportedEntities() const {
    return cast_or_null<MDTuple>(getRawImportedEntities());
  }

  MDString *getRawProducer() const { return getOperandAs<MDString>(1); }
  MDString *getRawFlags() const { return getOperandAs<MDString>(2); }
  MDString *getRawSplitDebugFilename() const {
    return getOperandAs<MDString>(3);
  }
  Metadata *getRawEnumTypes() const { return getOperand(4); }
  Metadata *getRawRetainedTypes() const { return getOperand(5); }
  Metadata *getRawSubprograms() const { return getOperand(6); }
  Metadata *getRawGlobalVariables() const { return getOperand(7); }
  Metadata *getRawImportedEntities() const { return getOperand(8); }

  /// \brief Replace arrays.
  ///
  /// If this \a isUniqued() and not \a isResolved(), it will be RAUW'ed and
  /// deleted on a uniquing collision.  In practice, uniquing collisions on \a
  /// MDCompileUnit should be fairly rare.
  /// @{
  void replaceSubprograms(MDTuple *N) { replaceOperandWith(6, N); }
  void replaceGlobalVariables(MDTuple *N) { replaceOperandWith(7, N); }
  /// @}

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDCompileUnitKind;
  }
};

/// \brief A scope for locals.
///
/// A legal scope for lexical blocks, local variables, and debug info
/// locations.  Subclasses are \a MDSubprogram, \a MDLexicalBlock, and \a
/// MDLexicalBlockFile.
class MDLocalScope : public MDScope {
protected:
  MDLocalScope(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
               ArrayRef<Metadata *> Ops)
      : MDScope(C, ID, Storage, Tag, Ops) {}
  ~MDLocalScope() {}

public:
  /// \brief Get the subprogram for this scope.
  ///
  /// Return this if it's an \a MDSubprogram; otherwise, look up the scope
  /// chain.
  MDSubprogram *getSubprogram() const;

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDSubprogramKind ||
           MD->getMetadataID() == MDLexicalBlockKind ||
           MD->getMetadataID() == MDLexicalBlockFileKind;
  }
};

/// \brief Debug location.
///
/// A debug location in source code, used for debug info and otherwise.
class MDLocation : public MDNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDLocation(LLVMContext &C, StorageType Storage, unsigned Line,
             unsigned Column, ArrayRef<Metadata *> MDs);
  ~MDLocation() { dropAllReferences(); }

  static MDLocation *getImpl(LLVMContext &Context, unsigned Line,
                             unsigned Column, Metadata *Scope,
                             Metadata *InlinedAt, StorageType Storage,
                             bool ShouldCreate = true);
  static MDLocation *getImpl(LLVMContext &Context, unsigned Line,
                             unsigned Column, MDLocalScope *Scope,
                             MDLocation *InlinedAt, StorageType Storage,
                             bool ShouldCreate = true) {
    return getImpl(Context, Line, Column, static_cast<Metadata *>(Scope),
                   static_cast<Metadata *>(InlinedAt), Storage, ShouldCreate);
  }

  TempMDLocation cloneImpl() const {
    return getTemporary(getContext(), getLine(), getColumn(), getScope(),
                        getInlinedAt());
  }

  // Disallow replacing operands.
  void replaceOperandWith(unsigned I, Metadata *New) = delete;

public:
  DEFINE_MDNODE_GET(MDLocation,
                    (unsigned Line, unsigned Column, Metadata *Scope,
                     Metadata *InlinedAt = nullptr),
                    (Line, Column, Scope, InlinedAt))
  DEFINE_MDNODE_GET(MDLocation,
                    (unsigned Line, unsigned Column, MDLocalScope *Scope,
                     MDLocation *InlinedAt = nullptr),
                    (Line, Column, Scope, InlinedAt))

  /// \brief Return a (temporary) clone of this.
  TempMDLocation clone() const { return cloneImpl(); }

  unsigned getLine() const { return SubclassData32; }
  unsigned getColumn() const { return SubclassData16; }
  MDLocalScope *getScope() const {
    return cast<MDLocalScope>(getRawScope());
  }
  MDLocation *getInlinedAt() const {
    return cast_or_null<MDLocation>(getRawInlinedAt());
  }

  /// \brief Get the scope where this is inlined.
  ///
  /// Walk through \a getInlinedAt() and return \a getScope() from the deepest
  /// location.
  MDLocalScope *getInlinedAtScope() const {
    if (auto *IA = getInlinedAt())
      return IA->getInlinedAtScope();
    return getScope();
  }

  Metadata *getRawScope() const { return getOperand(0); }
  Metadata *getRawInlinedAt() const {
    if (getNumOperands() == 2)
      return getOperand(1);
    return nullptr;
  }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDLocationKind;
  }
};

/// \brief Subprogram description.
///
/// TODO: Remove DisplayName.  It's always equal to Name.
/// TODO: Split up flags.
class MDSubprogram : public MDLocalScope {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Line;
  unsigned ScopeLine;
  unsigned Virtuality;
  unsigned VirtualIndex;
  unsigned Flags;
  bool IsLocalToUnit;
  bool IsDefinition;
  bool IsOptimized;

  MDSubprogram(LLVMContext &C, StorageType Storage, unsigned Line,
               unsigned ScopeLine, unsigned Virtuality, unsigned VirtualIndex,
               unsigned Flags, bool IsLocalToUnit, bool IsDefinition,
               bool IsOptimized, ArrayRef<Metadata *> Ops)
      : MDLocalScope(C, MDSubprogramKind, Storage, dwarf::DW_TAG_subprogram,
                     Ops),
        Line(Line), ScopeLine(ScopeLine), Virtuality(Virtuality),
        VirtualIndex(VirtualIndex), Flags(Flags), IsLocalToUnit(IsLocalToUnit),
        IsDefinition(IsDefinition), IsOptimized(IsOptimized) {}
  ~MDSubprogram() {}

  static MDSubprogram *
  getImpl(LLVMContext &Context, MDScopeRef Scope, StringRef Name,
          StringRef LinkageName, MDFile *File, unsigned Line,
          MDSubroutineType *Type, bool IsLocalToUnit, bool IsDefinition,
          unsigned ScopeLine, MDTypeRef ContainingType, unsigned Virtuality,
          unsigned VirtualIndex, unsigned Flags, bool IsOptimized,
          ConstantAsMetadata *Function, MDTemplateParameterArray TemplateParams,
          MDSubprogram *Declaration, MDLocalVariableArray Variables,
          StorageType Storage, bool ShouldCreate = true) {
    return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
                   getCanonicalMDString(Context, LinkageName), File, Line, Type,
                   IsLocalToUnit, IsDefinition, ScopeLine, ContainingType,
                   Virtuality, VirtualIndex, Flags, IsOptimized, Function,
                   TemplateParams, Declaration, Variables, Storage,
                   ShouldCreate);
  }
  static MDSubprogram *
  getImpl(LLVMContext &Context, Metadata *Scope, MDString *Name,
          MDString *LinkageName, Metadata *File, unsigned Line, Metadata *Type,
          bool IsLocalToUnit, bool IsDefinition, unsigned ScopeLine,
          Metadata *ContainingType, unsigned Virtuality, unsigned VirtualIndex,
          unsigned Flags, bool IsOptimized, Metadata *Function,
          Metadata *TemplateParams, Metadata *Declaration, Metadata *Variables,
          StorageType Storage, bool ShouldCreate = true);

  TempMDSubprogram cloneImpl() const {
    return getTemporary(getContext(), getScope(), getName(), getLinkageName(),
                        getFile(), getLine(), getType(), isLocalToUnit(),
                        isDefinition(), getScopeLine(), getContainingType(),
                        getVirtuality(), getVirtualIndex(), getFlags(),
                        isOptimized(), getFunction(), getTemplateParams(),
                        getDeclaration(), getVariables());
  }

public:
  DEFINE_MDNODE_GET(MDSubprogram,
                    (MDScopeRef Scope, StringRef Name, StringRef LinkageName,
                     MDFile *File, unsigned Line, MDSubroutineType *Type,
                     bool IsLocalToUnit, bool IsDefinition, unsigned ScopeLine,
                     MDTypeRef ContainingType, unsigned Virtuality,
                     unsigned VirtualIndex, unsigned Flags, bool IsOptimized,
                     ConstantAsMetadata *Function = nullptr,
                     MDTemplateParameterArray TemplateParams = nullptr,
                     MDSubprogram *Declaration = nullptr,
                     MDLocalVariableArray Variables = nullptr),
                    (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
                     IsDefinition, ScopeLine, ContainingType, Virtuality,
                     VirtualIndex, Flags, IsOptimized, Function, TemplateParams,
                     Declaration, Variables))
  DEFINE_MDNODE_GET(
      MDSubprogram,
      (Metadata * Scope, MDString *Name, MDString *LinkageName, Metadata *File,
       unsigned Line, Metadata *Type, bool IsLocalToUnit, bool IsDefinition,
       unsigned ScopeLine, Metadata *ContainingType, unsigned Virtuality,
       unsigned VirtualIndex, unsigned Flags, bool IsOptimized,
       Metadata *Function = nullptr, Metadata *TemplateParams = nullptr,
       Metadata *Declaration = nullptr, Metadata *Variables = nullptr),
      (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit, IsDefinition,
       ScopeLine, ContainingType, Virtuality, VirtualIndex, Flags, IsOptimized,
       Function, TemplateParams, Declaration, Variables))

  TempMDSubprogram clone() const { return cloneImpl(); }

public:
  unsigned getLine() const { return Line; }
  unsigned getVirtuality() const { return Virtuality; }
  unsigned getVirtualIndex() const { return VirtualIndex; }
  unsigned getScopeLine() const { return ScopeLine; }
  unsigned getFlags() const { return Flags; }
  bool isLocalToUnit() const { return IsLocalToUnit; }
  bool isDefinition() const { return IsDefinition; }
  bool isOptimized() const { return IsOptimized; }

  MDScopeRef getScope() const { return MDScopeRef(getRawScope()); }

  StringRef getName() const { return getStringOperand(2); }
  StringRef getDisplayName() const { return getStringOperand(3); }
  StringRef getLinkageName() const { return getStringOperand(4); }

  MDString *getRawName() const { return getOperandAs<MDString>(2); }
  MDString *getRawLinkageName() const { return getOperandAs<MDString>(4); }

  MDSubroutineType *getType() const {
    return cast_or_null<MDSubroutineType>(getRawType());
  }
  MDTypeRef getContainingType() const {
    return MDTypeRef(getRawContainingType());
  }

  ConstantAsMetadata *getFunction() const {
    return cast_or_null<ConstantAsMetadata>(getRawFunction());
  }
  MDTemplateParameterArray getTemplateParams() const {
    return cast_or_null<MDTuple>(getRawTemplateParams());
  }
  MDSubprogram *getDeclaration() const {
    return cast_or_null<MDSubprogram>(getRawDeclaration());
  }
  MDLocalVariableArray getVariables() const {
    return cast_or_null<MDTuple>(getRawVariables());
  }

  Metadata *getRawScope() const { return getOperand(1); }
  Metadata *getRawType() const { return getOperand(5); }
  Metadata *getRawContainingType() const { return getOperand(6); }
  Metadata *getRawFunction() const { return getOperand(7); }
  Metadata *getRawTemplateParams() const { return getOperand(8); }
  Metadata *getRawDeclaration() const { return getOperand(9); }
  Metadata *getRawVariables() const { return getOperand(10); }

  /// \brief Replace the function.
  ///
  /// If \a isUniqued() and not \a isResolved(), this could node will be
  /// RAUW'ed and deleted out from under the caller.  Use a \a TrackingMDRef if
  /// that's a problem.
  /// @{
  void replaceFunction(Function *F);
  void replaceFunction(ConstantAsMetadata *MD) { replaceOperandWith(7, MD); }
  void replaceFunction(std::nullptr_t) { replaceOperandWith(7, nullptr); }
  /// @}

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDSubprogramKind;
  }
};

class MDLexicalBlockBase : public MDLocalScope {
protected:
  MDLexicalBlockBase(LLVMContext &C, unsigned ID, StorageType Storage,
                     ArrayRef<Metadata *> Ops)
      : MDLocalScope(C, ID, Storage, dwarf::DW_TAG_lexical_block, Ops) {}
  ~MDLexicalBlockBase() {}

public:
  MDLocalScope *getScope() const { return cast<MDLocalScope>(getRawScope()); }

  Metadata *getRawScope() const { return getOperand(1); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDLexicalBlockKind ||
           MD->getMetadataID() == MDLexicalBlockFileKind;
  }
};

class MDLexicalBlock : public MDLexicalBlockBase {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Line;
  unsigned Column;

  MDLexicalBlock(LLVMContext &C, StorageType Storage, unsigned Line,
                 unsigned Column, ArrayRef<Metadata *> Ops)
      : MDLexicalBlockBase(C, MDLexicalBlockKind, Storage, Ops), Line(Line),
        Column(Column) {}
  ~MDLexicalBlock() {}

  static MDLexicalBlock *getImpl(LLVMContext &Context, MDLocalScope *Scope,
                                 MDFile *File, unsigned Line, unsigned Column,
                                 StorageType Storage,
                                 bool ShouldCreate = true) {
    return getImpl(Context, static_cast<Metadata *>(Scope),
                   static_cast<Metadata *>(File), Line, Column, Storage,
                   ShouldCreate);
  }

  static MDLexicalBlock *getImpl(LLVMContext &Context, Metadata *Scope,
                                 Metadata *File, unsigned Line, unsigned Column,
                                 StorageType Storage, bool ShouldCreate = true);

  TempMDLexicalBlock cloneImpl() const {
    return getTemporary(getContext(), getScope(), getFile(), getLine(),
                        getColumn());
  }

public:
  DEFINE_MDNODE_GET(MDLexicalBlock, (MDLocalScope * Scope, MDFile *File,
                                     unsigned Line, unsigned Column),
                    (Scope, File, Line, Column))
  DEFINE_MDNODE_GET(MDLexicalBlock, (Metadata * Scope, Metadata *File,
                                     unsigned Line, unsigned Column),
                    (Scope, File, Line, Column))

  TempMDLexicalBlock clone() const { return cloneImpl(); }

  unsigned getLine() const { return Line; }
  unsigned getColumn() const { return Column; }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDLexicalBlockKind;
  }
};

class MDLexicalBlockFile : public MDLexicalBlockBase {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Discriminator;

  MDLexicalBlockFile(LLVMContext &C, StorageType Storage,
                     unsigned Discriminator, ArrayRef<Metadata *> Ops)
      : MDLexicalBlockBase(C, MDLexicalBlockFileKind, Storage, Ops),
        Discriminator(Discriminator) {}
  ~MDLexicalBlockFile() {}

  static MDLexicalBlockFile *getImpl(LLVMContext &Context, MDLocalScope *Scope,
                                     MDFile *File, unsigned Discriminator,
                                     StorageType Storage,
                                     bool ShouldCreate = true) {
    return getImpl(Context, static_cast<Metadata *>(Scope),
                   static_cast<Metadata *>(File), Discriminator, Storage,
                   ShouldCreate);
  }

  static MDLexicalBlockFile *getImpl(LLVMContext &Context, Metadata *Scope,
                                     Metadata *File, unsigned Discriminator,
                                     StorageType Storage,
                                     bool ShouldCreate = true);

  TempMDLexicalBlockFile cloneImpl() const {
    return getTemporary(getContext(), getScope(), getFile(),
                        getDiscriminator());
  }

public:
  DEFINE_MDNODE_GET(MDLexicalBlockFile, (MDLocalScope * Scope, MDFile *File,
                                         unsigned Discriminator),
                    (Scope, File, Discriminator))
  DEFINE_MDNODE_GET(MDLexicalBlockFile,
                    (Metadata * Scope, Metadata *File, unsigned Discriminator),
                    (Scope, File, Discriminator))

  TempMDLexicalBlockFile clone() const { return cloneImpl(); }

  unsigned getDiscriminator() const { return Discriminator; }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDLexicalBlockFileKind;
  }
};

class MDNamespace : public MDScope {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Line;

  MDNamespace(LLVMContext &Context, StorageType Storage, unsigned Line,
              ArrayRef<Metadata *> Ops)
      : MDScope(Context, MDNamespaceKind, Storage, dwarf::DW_TAG_namespace,
                Ops),
        Line(Line) {}
  ~MDNamespace() {}

  static MDNamespace *getImpl(LLVMContext &Context, MDScope *Scope,
                              MDFile *File, StringRef Name, unsigned Line,
                              StorageType Storage, bool ShouldCreate = true) {
    return getImpl(Context, Scope, File, getCanonicalMDString(Context, Name),
                   Line, Storage, ShouldCreate);
  }
  static MDNamespace *getImpl(LLVMContext &Context, Metadata *Scope,
                              Metadata *File, MDString *Name, unsigned Line,
                              StorageType Storage, bool ShouldCreate = true);

  TempMDNamespace cloneImpl() const {
    return getTemporary(getContext(), getScope(), getFile(), getName(),
                        getLine());
  }

public:
  DEFINE_MDNODE_GET(MDNamespace, (MDScope * Scope, MDFile *File, StringRef Name,
                                  unsigned Line),
                    (Scope, File, Name, Line))
  DEFINE_MDNODE_GET(MDNamespace, (Metadata * Scope, Metadata *File,
                                  MDString *Name, unsigned Line),
                    (Scope, File, Name, Line))

  TempMDNamespace clone() const { return cloneImpl(); }

  unsigned getLine() const { return Line; }
  MDScope *getScope() const { return cast_or_null<MDScope>(getRawScope()); }
  StringRef getName() const { return getStringOperand(2); }

  Metadata *getRawScope() const { return getOperand(1); }
  MDString *getRawName() const { return getOperandAs<MDString>(2); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDNamespaceKind;
  }
};

/// \brief Base class for template parameters.
class MDTemplateParameter : public DebugNode {
protected:
  MDTemplateParameter(LLVMContext &Context, unsigned ID, StorageType Storage,
                      unsigned Tag, ArrayRef<Metadata *> Ops)
      : DebugNode(Context, ID, Storage, Tag, Ops) {}
  ~MDTemplateParameter() {}

public:
  StringRef getName() const { return getStringOperand(0); }
  MDTypeRef getType() const { return MDTypeRef(getRawType()); }

  MDString *getRawName() const { return getOperandAs<MDString>(0); }
  Metadata *getRawType() const { return getOperand(1); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDTemplateTypeParameterKind ||
           MD->getMetadataID() == MDTemplateValueParameterKind;
  }
};

class MDTemplateTypeParameter : public MDTemplateParameter {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDTemplateTypeParameter(LLVMContext &Context, StorageType Storage,
                          ArrayRef<Metadata *> Ops)
      : MDTemplateParameter(Context, MDTemplateTypeParameterKind, Storage,
                            dwarf::DW_TAG_template_type_parameter, Ops) {}
  ~MDTemplateTypeParameter() {}

  static MDTemplateTypeParameter *getImpl(LLVMContext &Context, StringRef Name,
                                          MDTypeRef Type, StorageType Storage,
                                          bool ShouldCreate = true) {
    return getImpl(Context, getCanonicalMDString(Context, Name), Type, Storage,
                   ShouldCreate);
  }
  static MDTemplateTypeParameter *getImpl(LLVMContext &Context, MDString *Name,
                                          Metadata *Type, StorageType Storage,
                                          bool ShouldCreate = true);

  TempMDTemplateTypeParameter cloneImpl() const {
    return getTemporary(getContext(), getName(), getType());
  }

public:
  DEFINE_MDNODE_GET(MDTemplateTypeParameter, (StringRef Name, MDTypeRef Type),
                    (Name, Type))
  DEFINE_MDNODE_GET(MDTemplateTypeParameter, (MDString * Name, Metadata *Type),
                    (Name, Type))

  TempMDTemplateTypeParameter clone() const { return cloneImpl(); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDTemplateTypeParameterKind;
  }
};

class MDTemplateValueParameter : public MDTemplateParameter {
  friend class LLVMContextImpl;
  friend class MDNode;

  MDTemplateValueParameter(LLVMContext &Context, StorageType Storage,
                           unsigned Tag, ArrayRef<Metadata *> Ops)
      : MDTemplateParameter(Context, MDTemplateValueParameterKind, Storage, Tag,
                            Ops) {}
  ~MDTemplateValueParameter() {}

  static MDTemplateValueParameter *getImpl(LLVMContext &Context, unsigned Tag,
                                           StringRef Name, MDTypeRef Type,
                                           Metadata *Value, StorageType Storage,
                                           bool ShouldCreate = true) {
    return getImpl(Context, Tag, getCanonicalMDString(Context, Name), Type,
                   Value, Storage, ShouldCreate);
  }
  static MDTemplateValueParameter *getImpl(LLVMContext &Context, unsigned Tag,
                                           MDString *Name, Metadata *Type,
                                           Metadata *Value, StorageType Storage,
                                           bool ShouldCreate = true);

  TempMDTemplateValueParameter cloneImpl() const {
    return getTemporary(getContext(), getTag(), getName(), getType(),
                        getValue());
  }

public:
  DEFINE_MDNODE_GET(MDTemplateValueParameter, (unsigned Tag, StringRef Name,
                                               MDTypeRef Type, Metadata *Value),
                    (Tag, Name, Type, Value))
  DEFINE_MDNODE_GET(MDTemplateValueParameter, (unsigned Tag, MDString *Name,
                                               Metadata *Type, Metadata *Value),
                    (Tag, Name, Type, Value))

  TempMDTemplateValueParameter clone() const { return cloneImpl(); }

  Metadata *getValue() const { return getOperand(2); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDTemplateValueParameterKind;
  }
};

/// \brief Base class for variables.
///
/// TODO: Hardcode to DW_TAG_variable.
class MDVariable : public DebugNode {
  unsigned Line;

protected:
  MDVariable(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
             unsigned Line, ArrayRef<Metadata *> Ops)
      : DebugNode(C, ID, Storage, Tag, Ops), Line(Line) {}
  ~MDVariable() {}

public:
  unsigned getLine() const { return Line; }
  MDScope *getScope() const { return cast_or_null<MDScope>(getRawScope()); }
  StringRef getName() const { return getStringOperand(1); }
  MDFile *getFile() const { return cast_or_null<MDFile>(getRawFile()); }
  MDTypeRef getType() const { return MDTypeRef(getRawType()); }

  Metadata *getRawScope() const { return getOperand(0); }
  MDString *getRawName() const { return getOperandAs<MDString>(1); }
  Metadata *getRawFile() const { return getOperand(2); }
  Metadata *getRawType() const { return getOperand(3); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDLocalVariableKind ||
           MD->getMetadataID() == MDGlobalVariableKind;
  }
};

/// \brief Global variables.
///
/// TODO: Remove DisplayName.  It's always equal to Name.
class MDGlobalVariable : public MDVariable {
  friend class LLVMContextImpl;
  friend class MDNode;

  bool IsLocalToUnit;
  bool IsDefinition;

  MDGlobalVariable(LLVMContext &C, StorageType Storage, unsigned Line,
                   bool IsLocalToUnit, bool IsDefinition,
                   ArrayRef<Metadata *> Ops)
      : MDVariable(C, MDGlobalVariableKind, Storage, dwarf::DW_TAG_variable,
                   Line, Ops),
        IsLocalToUnit(IsLocalToUnit), IsDefinition(IsDefinition) {}
  ~MDGlobalVariable() {}

  static MDGlobalVariable *
  getImpl(LLVMContext &Context, MDScope *Scope, StringRef Name,
          StringRef LinkageName, MDFile *File, unsigned Line, MDTypeRef Type,
          bool IsLocalToUnit, bool IsDefinition, ConstantAsMetadata *Variable,
          MDDerivedType *StaticDataMemberDeclaration, StorageType Storage,
          bool ShouldCreate = true) {
    return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
                   getCanonicalMDString(Context, LinkageName), File, Line, Type,
                   IsLocalToUnit, IsDefinition, Variable,
                   StaticDataMemberDeclaration, Storage, ShouldCreate);
  }
  static MDGlobalVariable *
  getImpl(LLVMContext &Context, Metadata *Scope, MDString *Name,
          MDString *LinkageName, Metadata *File, unsigned Line, Metadata *Type,
          bool IsLocalToUnit, bool IsDefinition, Metadata *Variable,
          Metadata *StaticDataMemberDeclaration, StorageType Storage,
          bool ShouldCreate = true);

  TempMDGlobalVariable cloneImpl() const {
    return getTemporary(getContext(), getScope(), getName(), getLinkageName(),
                        getFile(), getLine(), getType(), isLocalToUnit(),
                        isDefinition(), getVariable(),
                        getStaticDataMemberDeclaration());
  }

public:
  DEFINE_MDNODE_GET(MDGlobalVariable,
                    (MDScope * Scope, StringRef Name, StringRef LinkageName,
                     MDFile *File, unsigned Line, MDTypeRef Type,
                     bool IsLocalToUnit, bool IsDefinition,
                     ConstantAsMetadata *Variable,
                     MDDerivedType *StaticDataMemberDeclaration),
                    (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
                     IsDefinition, Variable, StaticDataMemberDeclaration))
  DEFINE_MDNODE_GET(MDGlobalVariable,
                    (Metadata * Scope, MDString *Name, MDString *LinkageName,
                     Metadata *File, unsigned Line, Metadata *Type,
                     bool IsLocalToUnit, bool IsDefinition, Metadata *Variable,
                     Metadata *StaticDataMemberDeclaration),
                    (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
                     IsDefinition, Variable, StaticDataMemberDeclaration))

  TempMDGlobalVariable clone() const { return cloneImpl(); }

  bool isLocalToUnit() const { return IsLocalToUnit; }
  bool isDefinition() const { return IsDefinition; }
  StringRef getDisplayName() const { return getStringOperand(4); }
  StringRef getLinkageName() const { return getStringOperand(5); }
  ConstantAsMetadata *getVariable() const {
    return cast_or_null<ConstantAsMetadata>(getRawVariable());
  }
  MDDerivedType *getStaticDataMemberDeclaration() const {
    return cast_or_null<MDDerivedType>(getRawStaticDataMemberDeclaration());
  }

  MDString *getRawLinkageName() const { return getOperandAs<MDString>(5); }
  Metadata *getRawVariable() const { return getOperand(6); }
  Metadata *getRawStaticDataMemberDeclaration() const { return getOperand(7); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDGlobalVariableKind;
  }
};

/// \brief Local variable.
///
/// TODO: Split between arguments and otherwise.
/// TODO: Use \c DW_TAG_variable instead of fake tags.
/// TODO: Split up flags.
class MDLocalVariable : public MDVariable {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Arg;
  unsigned Flags;

  MDLocalVariable(LLVMContext &C, StorageType Storage, unsigned Tag,
                  unsigned Line, unsigned Arg, unsigned Flags,
                  ArrayRef<Metadata *> Ops)
      : MDVariable(C, MDLocalVariableKind, Storage, Tag, Line, Ops), Arg(Arg),
        Flags(Flags) {}
  ~MDLocalVariable() {}

  static MDLocalVariable *getImpl(LLVMContext &Context, unsigned Tag,
                                  MDScope *Scope, StringRef Name, MDFile *File,
                                  unsigned Line, MDTypeRef Type, unsigned Arg,
                                  unsigned Flags, MDLocation *InlinedAt,
                                  StorageType Storage,
                                  bool ShouldCreate = true) {
    return getImpl(Context, Tag, Scope, getCanonicalMDString(Context, Name),
                   File, Line, Type, Arg, Flags, InlinedAt, Storage,
                   ShouldCreate);
  }
  static MDLocalVariable *getImpl(LLVMContext &Context, unsigned Tag,
                                  Metadata *Scope, MDString *Name,
                                  Metadata *File, unsigned Line, Metadata *Type,
                                  unsigned Arg, unsigned Flags,
                                  Metadata *InlinedAt, StorageType Storage,
                                  bool ShouldCreate = true);

  TempMDLocalVariable cloneImpl() const {
    return getTemporary(getContext(), getTag(), getScope(), getName(),
                        getFile(), getLine(), getType(), getArg(), getFlags(),
                        getInlinedAt());
  }

public:
  DEFINE_MDNODE_GET(MDLocalVariable,
                    (unsigned Tag, MDLocalScope *Scope, StringRef Name,
                     MDFile *File, unsigned Line, MDTypeRef Type, unsigned Arg,
                     unsigned Flags, MDLocation *InlinedAt = nullptr),
                    (Tag, Scope, Name, File, Line, Type, Arg, Flags, InlinedAt))
  DEFINE_MDNODE_GET(MDLocalVariable,
                    (unsigned Tag, Metadata *Scope, MDString *Name,
                     Metadata *File, unsigned Line, Metadata *Type,
                     unsigned Arg, unsigned Flags,
                     Metadata *InlinedAt = nullptr),
                    (Tag, Scope, Name, File, Line, Type, Arg, Flags, InlinedAt))

  TempMDLocalVariable clone() const { return cloneImpl(); }

  /// \brief Get the local scope for this variable.
  ///
  /// Variables must be defined in a local scope.
  MDLocalScope *getScope() const {
    return cast<MDLocalScope>(MDVariable::getScope());
  }

  unsigned getArg() const { return Arg; }
  unsigned getFlags() const { return Flags; }
  MDLocation *getInlinedAt() const {
    return cast_or_null<MDLocation>(getRawInlinedAt());
  }

  Metadata *getRawInlinedAt() const { return getOperand(4); }

  /// \brief Check that a location is valid for this variable.
  ///
  /// Check that \c DL has the same inlined-at location as this variable,
  /// making them valid for the same \a DbgInfoIntrinsic.
  bool isValidLocationForIntrinsic(const MDLocation *DL) const {
    return getInlinedAt() == (DL ? DL->getInlinedAt() : nullptr);
  }

  /// \brief Get an inlined version of this variable.
  ///
  /// Returns a version of this with \a getAlinedAt() set to \c InlinedAt.
  MDLocalVariable *withInline(MDLocation *InlinedAt) const {
    if (InlinedAt == getInlinedAt())
      return const_cast<MDLocalVariable *>(this);
    auto Temp = clone();
    Temp->replaceOperandWith(4, InlinedAt);
    return replaceWithUniqued(std::move(Temp));
  }
  MDLocalVariable *withoutInline() const { return withInline(nullptr); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDLocalVariableKind;
  }
};

/// \brief DWARF expression.
///
/// TODO: Co-allocate the expression elements.
/// TODO: Separate from MDNode, or otherwise drop Distinct and Temporary
/// storage types.
class MDExpression : public MDNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  std::vector<uint64_t> Elements;

  MDExpression(LLVMContext &C, StorageType Storage, ArrayRef<uint64_t> Elements)
      : MDNode(C, MDExpressionKind, Storage, None),
        Elements(Elements.begin(), Elements.end()) {}
  ~MDExpression() {}

  static MDExpression *getImpl(LLVMContext &Context,
                               ArrayRef<uint64_t> Elements, StorageType Storage,
                               bool ShouldCreate = true);

  TempMDExpression cloneImpl() const {
    return getTemporary(getContext(), getElements());
  }

public:
  DEFINE_MDNODE_GET(MDExpression, (ArrayRef<uint64_t> Elements), (Elements))

  TempMDExpression clone() const { return cloneImpl(); }

  ArrayRef<uint64_t> getElements() const { return Elements; }

  unsigned getNumElements() const { return Elements.size(); }
  uint64_t getElement(unsigned I) const {
    assert(I < Elements.size() && "Index out of range");
    return Elements[I];
  }

  typedef ArrayRef<uint64_t>::iterator element_iterator;
  element_iterator elements_begin() const { return getElements().begin(); }
  element_iterator elements_end() const { return getElements().end(); }

  /// \brief A lightweight wrapper around an expression operand.
  ///
  /// TODO: Store arguments directly and change \a MDExpression to store a
  /// range of these.
  class ExprOperand {
    const uint64_t *Op;

  public:
    explicit ExprOperand(const uint64_t *Op) : Op(Op) {}

    const uint64_t *get() const { return Op; }

    /// \brief Get the operand code.
    uint64_t getOp() const { return *Op; }

    /// \brief Get an argument to the operand.
    ///
    /// Never returns the operand itself.
    uint64_t getArg(unsigned I) const { return Op[I + 1]; }

    unsigned getNumArgs() const { return getSize() - 1; }

    /// \brief Return the size of the operand.
    ///
    /// Return the number of elements in the operand (1 + args).
    unsigned getSize() const;
  };

  /// \brief An iterator for expression operands.
  class expr_op_iterator
      : public std::iterator<std::input_iterator_tag, ExprOperand> {
    ExprOperand Op;

  public:
    explicit expr_op_iterator(element_iterator I) : Op(I) {}

    element_iterator getBase() const { return Op.get(); }
    const ExprOperand &operator*() const { return Op; }
    const ExprOperand *operator->() const { return &Op; }

    expr_op_iterator &operator++() {
      increment();
      return *this;
    }
    expr_op_iterator operator++(int) {
      expr_op_iterator T(*this);
      increment();
      return T;
    }

    bool operator==(const expr_op_iterator &X) const {
      return getBase() == X.getBase();
    }
    bool operator!=(const expr_op_iterator &X) const {
      return getBase() != X.getBase();
    }

  private:
    void increment() { Op = ExprOperand(getBase() + Op.getSize()); }
  };

  /// \brief Visit the elements via ExprOperand wrappers.
  ///
  /// These range iterators visit elements through \a ExprOperand wrappers.
  /// This is not guaranteed to be a valid range unless \a isValid() gives \c
  /// true.
  ///
  /// \pre \a isValid() gives \c true.
  /// @{
  expr_op_iterator expr_op_begin() const {
    return expr_op_iterator(elements_begin());
  }
  expr_op_iterator expr_op_end() const {
    return expr_op_iterator(elements_end());
  }
  /// @}

  bool isValid() const;

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDExpressionKind;
  }
};

class MDObjCProperty : public DebugNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Line;
  unsigned Attributes;

  MDObjCProperty(LLVMContext &C, StorageType Storage, unsigned Line,
                 unsigned Attributes, ArrayRef<Metadata *> Ops)
      : DebugNode(C, MDObjCPropertyKind, Storage, dwarf::DW_TAG_APPLE_property,
                  Ops),
        Line(Line), Attributes(Attributes) {}
  ~MDObjCProperty() {}

  static MDObjCProperty *
  getImpl(LLVMContext &Context, StringRef Name, MDFile *File, unsigned Line,
          StringRef GetterName, StringRef SetterName, unsigned Attributes,
          MDType *Type, StorageType Storage, bool ShouldCreate = true) {
    return getImpl(Context, getCanonicalMDString(Context, Name), File, Line,
                   getCanonicalMDString(Context, GetterName),
                   getCanonicalMDString(Context, SetterName), Attributes, Type,
                   Storage, ShouldCreate);
  }
  static MDObjCProperty *getImpl(LLVMContext &Context, MDString *Name,
                                 Metadata *File, unsigned Line,
                                 MDString *GetterName, MDString *SetterName,
                                 unsigned Attributes, Metadata *Type,
                                 StorageType Storage, bool ShouldCreate = true);

  TempMDObjCProperty cloneImpl() const {
    return getTemporary(getContext(), getName(), getFile(), getLine(),
                        getGetterName(), getSetterName(), getAttributes(),
                        getType());
  }

public:
  DEFINE_MDNODE_GET(MDObjCProperty,
                    (StringRef Name, MDFile *File, unsigned Line,
                     StringRef GetterName, StringRef SetterName,
                     unsigned Attributes, MDType *Type),
                    (Name, File, Line, GetterName, SetterName, Attributes,
                     Type))
  DEFINE_MDNODE_GET(MDObjCProperty,
                    (MDString * Name, Metadata *File, unsigned Line,
                     MDString *GetterName, MDString *SetterName,
                     unsigned Attributes, Metadata *Type),
                    (Name, File, Line, GetterName, SetterName, Attributes,
                     Type))

  TempMDObjCProperty clone() const { return cloneImpl(); }

  unsigned getLine() const { return Line; }
  unsigned getAttributes() const { return Attributes; }
  StringRef getName() const { return getStringOperand(0); }
  MDFile *getFile() const { return cast_or_null<MDFile>(getRawFile()); }
  StringRef getGetterName() const { return getStringOperand(2); }
  StringRef getSetterName() const { return getStringOperand(3); }
  MDType *getType() const { return cast_or_null<MDType>(getRawType()); }

  MDString *getRawName() const { return getOperandAs<MDString>(0); }
  Metadata *getRawFile() const { return getOperand(1); }
  MDString *getRawGetterName() const { return getOperandAs<MDString>(2); }
  MDString *getRawSetterName() const { return getOperandAs<MDString>(3); }
  Metadata *getRawType() const { return getOperand(4); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDObjCPropertyKind;
  }
};

class MDImportedEntity : public DebugNode {
  friend class LLVMContextImpl;
  friend class MDNode;

  unsigned Line;

  MDImportedEntity(LLVMContext &C, StorageType Storage, unsigned Tag,
                   unsigned Line, ArrayRef<Metadata *> Ops)
      : DebugNode(C, MDImportedEntityKind, Storage, Tag, Ops), Line(Line) {}
  ~MDImportedEntity() {}

  static MDImportedEntity *getImpl(LLVMContext &Context, unsigned Tag,
                                   MDScope *Scope, Metadata *Entity,
                                   unsigned Line, StringRef Name,
                                   StorageType Storage,
                                   bool ShouldCreate = true) {
    return getImpl(Context, Tag, Scope, Entity, Line,
                   getCanonicalMDString(Context, Name), Storage, ShouldCreate);
  }
  static MDImportedEntity *getImpl(LLVMContext &Context, unsigned Tag,
                                   Metadata *Scope, Metadata *Entity,
                                   unsigned Line, MDString *Name,
                                   StorageType Storage,
                                   bool ShouldCreate = true);

  TempMDImportedEntity cloneImpl() const {
    return getTemporary(getContext(), getTag(), getScope(), getEntity(),
                        getLine(), getName());
  }

public:
  DEFINE_MDNODE_GET(MDImportedEntity,
                    (unsigned Tag, MDScope *Scope, Metadata *Entity,
                     unsigned Line, StringRef Name = ""),
                    (Tag, Scope, Entity, Line, Name))
  DEFINE_MDNODE_GET(MDImportedEntity,
                    (unsigned Tag, Metadata *Scope, Metadata *Entity,
                     unsigned Line, MDString *Name),
                    (Tag, Scope, Entity, Line, Name))

  TempMDImportedEntity clone() const { return cloneImpl(); }

  unsigned getLine() const { return Line; }
  MDScope *getScope() const { return cast_or_null<MDScope>(getRawScope()); }
  Metadata *getEntity() const { return getRawEntity(); }
  StringRef getName() const { return getStringOperand(2); }

  Metadata *getRawScope() const { return getOperand(0); }
  Metadata *getRawEntity() const { return getOperand(1); }
  MDString *getRawName() const { return getOperandAs<MDString>(2); }

  static bool classof(const Metadata *MD) {
    return MD->getMetadataID() == MDImportedEntityKind;
  }
};

} // end namespace llvm

#undef DEFINE_MDNODE_GET_UNPACK_IMPL
#undef DEFINE_MDNODE_GET_UNPACK
#undef DEFINE_MDNODE_GET

#endif