Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/IR/DebugInfoMetadata.h b/linux-x64/clang/include/llvm/IR/DebugInfoMetadata.h
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+++ b/linux-x64/clang/include/llvm/IR/DebugInfoMetadata.h
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+//===- 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/ADT/ArrayRef.h"
+#include "llvm/ADT/BitmaskEnum.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/Support/Casting.h"
+#include <cassert>
+#include <climits>
+#include <cstddef>
+#include <cstdint>
+#include <iterator>
+#include <type_traits>
+#include <vector>
+
+// 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_DISTINCT_TEMPORARY(CLASS, FORMAL, ARGS)              \
+  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));          \
+  }
+#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);                                  \
+  }                                                                            \
+  DEFINE_MDNODE_GET_DISTINCT_TEMPORARY(CLASS, FORMAL, ARGS)
+
+namespace llvm {
+
+/// Holds a subclass of DINode.
+///
+/// FIXME: This class doesn't currently make much sense.  Previously it was a
+/// union beteen MDString (for ODR-uniqued types) and things like DIType.  To
+/// support CodeView work, it wasn't deleted outright when MDString-based type
+/// references were deleted; we'll soon need a similar concept for CodeView
+/// DITypeIndex.
+template <class T> class TypedDINodeRef {
+  const Metadata *MD = nullptr;
+
+public:
+  TypedDINodeRef() = default;
+  TypedDINodeRef(std::nullptr_t) {}
+  TypedDINodeRef(const T *MD) : MD(MD) {}
+
+  explicit TypedDINodeRef(const Metadata *MD) : MD(MD) {
+    assert((!MD || isa<T>(MD)) && "Expected valid type ref");
+  }
+
+  template <class U>
+  TypedDINodeRef(
+      const TypedDINodeRef<U> &X,
+      typename std::enable_if<std::is_convertible<U *, T *>::value>::type * =
+          nullptr)
+      : MD(X) {}
+
+  operator Metadata *() const { return const_cast<Metadata *>(MD); }
+
+  T *resolve() const { return const_cast<T *>(cast_or_null<T>(MD)); }
+
+  bool operator==(const TypedDINodeRef<T> &X) const { return MD == X.MD; }
+  bool operator!=(const TypedDINodeRef<T> &X) const { return MD != X.MD; }
+};
+
+using DINodeRef = TypedDINodeRef<DINode>;
+using DIScopeRef = TypedDINodeRef<DIScope>;
+using DITypeRef = TypedDINodeRef<DIType>;
+
+class DITypeRefArray {
+  const MDTuple *N = nullptr;
+
+public:
+  DITypeRefArray() = default;
+  DITypeRefArray(const MDTuple *N) : N(N) {}
+
+  explicit operator bool() const { return get(); }
+  explicit operator MDTuple *() const { return get(); }
+
+  MDTuple *get() const { return const_cast<MDTuple *>(N); }
+  MDTuple *operator->() const { return get(); }
+  MDTuple &operator*() const { return *get(); }
+
+  // FIXME: Fix callers and remove condition on N.
+  unsigned size() const { return N ? N->getNumOperands() : 0u; }
+  DITypeRef operator[](unsigned I) const { return DITypeRef(N->getOperand(I)); }
+
+  class iterator : std::iterator<std::input_iterator_tag, DITypeRef,
+                                 std::ptrdiff_t, void, DITypeRef> {
+    MDNode::op_iterator I = nullptr;
+
+  public:
+    iterator() = default;
+    explicit iterator(MDNode::op_iterator I) : I(I) {}
+
+    DITypeRef operator*() const { return DITypeRef(*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; }
+  };
+
+  // FIXME: Fix callers and remove condition on N.
+  iterator begin() const { return N ? iterator(N->op_begin()) : iterator(); }
+  iterator end() const { return N ? iterator(N->op_end()) : iterator(); }
+};
+
+/// Tagged DWARF-like metadata node.
+///
+/// A metadata node with a DWARF tag (i.e., a constant named \c DW_TAG_*,
+/// defined in llvm/BinaryFormat/Dwarf.h).  Called \a DINode because it's
+/// potentially used for non-DWARF output.
+class DINode : public MDNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+protected:
+  DINode(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;
+  }
+  ~DINode() = default;
+
+  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);
+  }
+
+  /// Allow subclasses to mutate the tag.
+  void setTag(unsigned Tag) { SubclassData16 = Tag; }
+
+public:
+  unsigned getTag() const { return SubclassData16; }
+
+  /// Debug info flags.
+  ///
+  /// The three accessibility flags are mutually exclusive and rolled together
+  /// in the first two bits.
+  enum DIFlags : uint32_t {
+#define HANDLE_DI_FLAG(ID, NAME) Flag##NAME = ID,
+#define DI_FLAG_LARGEST_NEEDED
+#include "llvm/IR/DebugInfoFlags.def"
+    FlagAccessibility = FlagPrivate | FlagProtected | FlagPublic,
+    FlagPtrToMemberRep = FlagSingleInheritance | FlagMultipleInheritance |
+                         FlagVirtualInheritance,
+    LLVM_MARK_AS_BITMASK_ENUM(FlagLargest)
+  };
+
+  static DIFlags getFlag(StringRef Flag);
+  static StringRef getFlagString(DIFlags Flag);
+
+  /// Split up a flags bitfield.
+  ///
+  /// Split \c Flags into \c SplitFlags, a vector of its components.  Returns
+  /// any remaining (unrecognized) bits.
+  static DIFlags splitFlags(DIFlags Flags,
+                            SmallVectorImpl<DIFlags> &SplitFlags);
+
+  static bool classof(const Metadata *MD) {
+    switch (MD->getMetadataID()) {
+    default:
+      return false;
+    case GenericDINodeKind:
+    case DISubrangeKind:
+    case DIEnumeratorKind:
+    case DIBasicTypeKind:
+    case DIDerivedTypeKind:
+    case DICompositeTypeKind:
+    case DISubroutineTypeKind:
+    case DIFileKind:
+    case DICompileUnitKind:
+    case DISubprogramKind:
+    case DILexicalBlockKind:
+    case DILexicalBlockFileKind:
+    case DINamespaceKind:
+    case DITemplateTypeParameterKind:
+    case DITemplateValueParameterKind:
+    case DIGlobalVariableKind:
+    case DILocalVariableKind:
+    case DIObjCPropertyKind:
+    case DIImportedEntityKind:
+    case DIModuleKind:
+      return true;
+    }
+  }
+};
+
+template <class T> struct simplify_type<const TypedDINodeRef<T>> {
+  using SimpleType = Metadata *;
+
+  static SimpleType getSimplifiedValue(const TypedDINodeRef<T> &MD) {
+    return MD;
+  }
+};
+
+template <class T>
+struct simplify_type<TypedDINodeRef<T>>
+    : simplify_type<const TypedDINodeRef<T>> {};
+
+/// 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 GenericDINode : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  GenericDINode(LLVMContext &C, StorageType Storage, unsigned Hash,
+                unsigned Tag, ArrayRef<Metadata *> Ops1,
+                ArrayRef<Metadata *> Ops2)
+      : DINode(C, GenericDINodeKind, Storage, Tag, Ops1, Ops2) {
+    setHash(Hash);
+  }
+  ~GenericDINode() { dropAllReferences(); }
+
+  void setHash(unsigned Hash) { SubclassData32 = Hash; }
+  void recalculateHash();
+
+  static GenericDINode *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 GenericDINode *getImpl(LLVMContext &Context, unsigned Tag,
+                                MDString *Header, ArrayRef<Metadata *> DwarfOps,
+                                StorageType Storage, bool ShouldCreate = true);
+
+  TempGenericDINode 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(GenericDINode, (unsigned Tag, StringRef Header,
+                                    ArrayRef<Metadata *> DwarfOps),
+                    (Tag, Header, DwarfOps))
+  DEFINE_MDNODE_GET(GenericDINode, (unsigned Tag, MDString *Header,
+                                    ArrayRef<Metadata *> DwarfOps),
+                    (Tag, Header, DwarfOps))
+
+  /// Return a (temporary) clone of this.
+  TempGenericDINode clone() const { return cloneImpl(); }
+
+  unsigned getTag() const { return SubclassData16; }
+  StringRef getHeader() const { return getStringOperand(0); }
+  MDString *getRawHeader() const { return getOperandAs<MDString>(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() == GenericDINodeKind;
+  }
+};
+
+/// Array subrange.
+///
+/// TODO: Merge into node for DW_TAG_array_type, which should have a custom
+/// type.
+class DISubrange : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  int64_t LowerBound;
+
+  DISubrange(LLVMContext &C, StorageType Storage, Metadata *Node,
+             int64_t LowerBound, ArrayRef<Metadata *> Ops)
+      : DINode(C, DISubrangeKind, Storage, dwarf::DW_TAG_subrange_type, Ops),
+        LowerBound(LowerBound) {}
+
+  ~DISubrange() = default;
+
+  static DISubrange *getImpl(LLVMContext &Context, int64_t Count,
+                             int64_t LowerBound, StorageType Storage,
+                             bool ShouldCreate = true);
+
+  static DISubrange *getImpl(LLVMContext &Context, Metadata *CountNode,
+                             int64_t LowerBound, StorageType Storage,
+                             bool ShouldCreate = true);
+
+  TempDISubrange cloneImpl() const {
+    return getTemporary(getContext(), getRawCountNode(), getLowerBound());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DISubrange, (int64_t Count, int64_t LowerBound = 0),
+                    (Count, LowerBound))
+
+  DEFINE_MDNODE_GET(DISubrange, (Metadata *CountNode, int64_t LowerBound = 0),
+                    (CountNode, LowerBound))
+
+  TempDISubrange clone() const { return cloneImpl(); }
+
+  int64_t getLowerBound() const { return LowerBound; }
+
+  Metadata *getRawCountNode() const {
+    return getOperand(0).get();
+  }
+
+  typedef PointerUnion<ConstantInt*, DIVariable*> CountType;
+
+  CountType getCount() const {
+    if (auto *MD = dyn_cast<ConstantAsMetadata>(getRawCountNode()))
+      return CountType(cast<ConstantInt>(MD->getValue()));
+
+    if (auto *DV = dyn_cast<DIVariable>(getRawCountNode()))
+      return CountType(DV);
+
+    return CountType();
+  }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DISubrangeKind;
+  }
+};
+
+/// Enumeration value.
+///
+/// TODO: Add a pointer to the context (DW_TAG_enumeration_type) once that no
+/// longer creates a type cycle.
+class DIEnumerator : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  int64_t Value;
+  DIEnumerator(LLVMContext &C, StorageType Storage, int64_t Value,
+               bool IsUnsigned, ArrayRef<Metadata *> Ops)
+      : DINode(C, DIEnumeratorKind, Storage, dwarf::DW_TAG_enumerator, Ops),
+        Value(Value) {
+    SubclassData32 = IsUnsigned;
+  }
+  ~DIEnumerator() = default;
+
+  static DIEnumerator *getImpl(LLVMContext &Context, int64_t Value,
+                               bool IsUnsigned, StringRef Name,
+                               StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(Context, Value, IsUnsigned,
+                   getCanonicalMDString(Context, Name), Storage, ShouldCreate);
+  }
+  static DIEnumerator *getImpl(LLVMContext &Context, int64_t Value,
+                               bool IsUnsigned, MDString *Name,
+                               StorageType Storage, bool ShouldCreate = true);
+
+  TempDIEnumerator cloneImpl() const {
+    return getTemporary(getContext(), getValue(), isUnsigned(), getName());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIEnumerator, (int64_t Value, bool IsUnsigned, StringRef Name),
+                    (Value, IsUnsigned, Name))
+  DEFINE_MDNODE_GET(DIEnumerator, (int64_t Value, bool IsUnsigned, MDString *Name),
+                    (Value, IsUnsigned, Name))
+
+  TempDIEnumerator clone() const { return cloneImpl(); }
+
+  int64_t getValue() const { return Value; }
+  bool isUnsigned() const { return SubclassData32; }
+  StringRef getName() const { return getStringOperand(0); }
+
+  MDString *getRawName() const { return getOperandAs<MDString>(0); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIEnumeratorKind;
+  }
+};
+
+/// 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 DIScope : public DINode {
+protected:
+  DIScope(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
+          ArrayRef<Metadata *> Ops)
+      : DINode(C, ID, Storage, Tag, Ops) {}
+  ~DIScope() = default;
+
+public:
+  DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
+
+  inline StringRef getFilename() const;
+  inline StringRef getDirectory() const;
+  inline Optional<StringRef> getSource() const;
+
+  StringRef getName() const;
+  DIScopeRef getScope() const;
+
+  /// Return the raw underlying file.
+  ///
+  /// A \a DIFile is a \a DIScope, but it doesn't point at a separate file (it
+  /// \em is the file).  If \c this is an \a DIFile, 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<DIFile>(this) ? const_cast<DIScope *>(this)
+                             : static_cast<Metadata *>(getOperand(0));
+  }
+
+  static bool classof(const Metadata *MD) {
+    switch (MD->getMetadataID()) {
+    default:
+      return false;
+    case DIBasicTypeKind:
+    case DIDerivedTypeKind:
+    case DICompositeTypeKind:
+    case DISubroutineTypeKind:
+    case DIFileKind:
+    case DICompileUnitKind:
+    case DISubprogramKind:
+    case DILexicalBlockKind:
+    case DILexicalBlockFileKind:
+    case DINamespaceKind:
+    case DIModuleKind:
+      return true;
+    }
+  }
+};
+
+/// File.
+///
+/// TODO: Merge with directory/file node (including users).
+/// TODO: Canonicalize paths on creation.
+class DIFile : public DIScope {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+public:
+  /// Which algorithm (e.g. MD5) a checksum was generated with.
+  ///
+  /// The encoding is explicit because it is used directly in Bitcode. The
+  /// value 0 is reserved to indicate the absence of a checksum in Bitcode.
+  enum ChecksumKind {
+    // The first variant was originally CSK_None, encoded as 0. The new
+    // internal representation removes the need for this by wrapping the
+    // ChecksumInfo in an Optional, but to preserve Bitcode compatibility the 0
+    // encoding is reserved.
+    CSK_MD5 = 1,
+    CSK_SHA1 = 2,
+    CSK_Last = CSK_SHA1 // Should be last enumeration.
+  };
+
+  /// A single checksum, represented by a \a Kind and a \a Value (a string).
+  template <typename T>
+  struct ChecksumInfo {
+    /// The kind of checksum which \a Value encodes.
+    ChecksumKind Kind;
+    /// The string value of the checksum.
+    T Value;
+
+    ChecksumInfo(ChecksumKind Kind, T Value) : Kind(Kind), Value(Value) { }
+    ~ChecksumInfo() = default;
+    bool operator==(const ChecksumInfo<T> &X) const {
+      return Kind == X.Kind && Value == X.Value;
+    }
+    bool operator!=(const ChecksumInfo<T> &X) const { return !(*this == X); }
+    StringRef getKindAsString() const { return getChecksumKindAsString(Kind); }
+  };
+
+private:
+  Optional<ChecksumInfo<MDString *>> Checksum;
+  Optional<MDString *> Source;
+
+  DIFile(LLVMContext &C, StorageType Storage,
+         Optional<ChecksumInfo<MDString *>> CS, Optional<MDString *> Src,
+         ArrayRef<Metadata *> Ops)
+      : DIScope(C, DIFileKind, Storage, dwarf::DW_TAG_file_type, Ops),
+        Checksum(CS), Source(Src) {}
+  ~DIFile() = default;
+
+  static DIFile *getImpl(LLVMContext &Context, StringRef Filename,
+                         StringRef Directory,
+                         Optional<ChecksumInfo<StringRef>> CS,
+                         Optional<StringRef> Source,
+                         StorageType Storage, bool ShouldCreate = true) {
+    Optional<ChecksumInfo<MDString *>> MDChecksum;
+    if (CS)
+      MDChecksum.emplace(CS->Kind, getCanonicalMDString(Context, CS->Value));
+    return getImpl(Context, getCanonicalMDString(Context, Filename),
+                   getCanonicalMDString(Context, Directory), MDChecksum,
+                   Source ? Optional<MDString *>(getCanonicalMDString(Context, *Source)) : None,
+                   Storage, ShouldCreate);
+  }
+  static DIFile *getImpl(LLVMContext &Context, MDString *Filename,
+                         MDString *Directory,
+                         Optional<ChecksumInfo<MDString *>> CS,
+                         Optional<MDString *> Source, StorageType Storage,
+                         bool ShouldCreate = true);
+
+  TempDIFile cloneImpl() const {
+    return getTemporary(getContext(), getFilename(), getDirectory(),
+                        getChecksum(), getSource());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIFile, (StringRef Filename, StringRef Directory,
+                             Optional<ChecksumInfo<StringRef>> CS = None,
+                             Optional<StringRef> Source = None),
+                    (Filename, Directory, CS, Source))
+  DEFINE_MDNODE_GET(DIFile, (MDString * Filename, MDString *Directory,
+                             Optional<ChecksumInfo<MDString *>> CS = None,
+                             Optional<MDString *> Source = None),
+                    (Filename, Directory, CS, Source))
+
+  TempDIFile clone() const { return cloneImpl(); }
+
+  StringRef getFilename() const { return getStringOperand(0); }
+  StringRef getDirectory() const { return getStringOperand(1); }
+  Optional<ChecksumInfo<StringRef>> getChecksum() const {
+    Optional<ChecksumInfo<StringRef>> StringRefChecksum;
+    if (Checksum)
+      StringRefChecksum.emplace(Checksum->Kind, Checksum->Value->getString());
+    return StringRefChecksum;
+  }
+  Optional<StringRef> getSource() const {
+    return Source ? Optional<StringRef>((*Source)->getString()) : None;
+  }
+
+  MDString *getRawFilename() const { return getOperandAs<MDString>(0); }
+  MDString *getRawDirectory() const { return getOperandAs<MDString>(1); }
+  Optional<ChecksumInfo<MDString *>> getRawChecksum() const { return Checksum; }
+  Optional<MDString *> getRawSource() const { return Source; }
+
+  static StringRef getChecksumKindAsString(ChecksumKind CSKind);
+  static Optional<ChecksumKind> getChecksumKind(StringRef CSKindStr);
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIFileKind;
+  }
+};
+
+StringRef DIScope::getFilename() const {
+  if (auto *F = getFile())
+    return F->getFilename();
+  return "";
+}
+
+StringRef DIScope::getDirectory() const {
+  if (auto *F = getFile())
+    return F->getDirectory();
+  return "";
+}
+
+Optional<StringRef> DIScope::getSource() const {
+  if (auto *F = getFile())
+    return F->getSource();
+  return None;
+}
+
+/// Base class for types.
+///
+/// TODO: Remove the hardcoded name and context, since many types don't use
+/// them.
+/// TODO: Split up flags.
+class DIType : public DIScope {
+  unsigned Line;
+  DIFlags Flags;
+  uint64_t SizeInBits;
+  uint64_t OffsetInBits;
+  uint32_t AlignInBits;
+
+protected:
+  DIType(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
+         unsigned Line, uint64_t SizeInBits, uint32_t AlignInBits,
+         uint64_t OffsetInBits, DIFlags Flags, ArrayRef<Metadata *> Ops)
+      : DIScope(C, ID, Storage, Tag, Ops) {
+    init(Line, SizeInBits, AlignInBits, OffsetInBits, Flags);
+  }
+  ~DIType() = default;
+
+  void init(unsigned Line, uint64_t SizeInBits, uint32_t AlignInBits,
+            uint64_t OffsetInBits, DIFlags Flags) {
+    this->Line = Line;
+    this->Flags = Flags;
+    this->SizeInBits = SizeInBits;
+    this->AlignInBits = AlignInBits;
+    this->OffsetInBits = OffsetInBits;
+  }
+
+  /// Change fields in place.
+  void mutate(unsigned Tag, unsigned Line, uint64_t SizeInBits,
+              uint32_t AlignInBits, uint64_t OffsetInBits, DIFlags Flags) {
+    assert(isDistinct() && "Only distinct nodes can mutate");
+    setTag(Tag);
+    init(Line, SizeInBits, AlignInBits, OffsetInBits, Flags);
+  }
+
+public:
+  TempDIType clone() const {
+    return TempDIType(cast<DIType>(MDNode::clone().release()));
+  }
+
+  unsigned getLine() const { return Line; }
+  uint64_t getSizeInBits() const { return SizeInBits; }
+  uint32_t getAlignInBits() const { return AlignInBits; }
+  uint32_t getAlignInBytes() const { return getAlignInBits() / CHAR_BIT; }
+  uint64_t getOffsetInBits() const { return OffsetInBits; }
+  DIFlags getFlags() const { return Flags; }
+
+  DIScopeRef getScope() const { return DIScopeRef(getRawScope()); }
+  StringRef getName() const { return getStringOperand(2); }
+
+
+  Metadata *getRawScope() const { return getOperand(1); }
+  MDString *getRawName() const { return getOperandAs<MDString>(2); }
+
+  void setFlags(DIFlags NewFlags) {
+    assert(!isUniqued() && "Cannot set flags on uniqued nodes");
+    Flags = NewFlags;
+  }
+
+  bool isPrivate() const {
+    return (getFlags() & FlagAccessibility) == FlagPrivate;
+  }
+  bool isProtected() const {
+    return (getFlags() & FlagAccessibility) == FlagProtected;
+  }
+  bool isPublic() const {
+    return (getFlags() & FlagAccessibility) == FlagPublic;
+  }
+  bool isForwardDecl() const { return getFlags() & FlagFwdDecl; }
+  bool isAppleBlockExtension() const { return getFlags() & FlagAppleBlock; }
+  bool isBlockByrefStruct() const { return getFlags() & FlagBlockByrefStruct; }
+  bool isVirtual() const { return getFlags() & FlagVirtual; }
+  bool isArtificial() const { return getFlags() & FlagArtificial; }
+  bool isObjectPointer() const { return getFlags() & FlagObjectPointer; }
+  bool isObjcClassComplete() const {
+    return getFlags() & FlagObjcClassComplete;
+  }
+  bool isVector() const { return getFlags() & FlagVector; }
+  bool isBitField() const { return getFlags() & FlagBitField; }
+  bool isStaticMember() const { return getFlags() & FlagStaticMember; }
+  bool isLValueReference() const { return getFlags() & FlagLValueReference; }
+  bool isRValueReference() const { return getFlags() & FlagRValueReference; }
+  bool isTypePassByValue() const { return getFlags() & FlagTypePassByValue; }
+  bool isTypePassByReference() const {
+    return getFlags() & FlagTypePassByReference;
+  }
+
+  static bool classof(const Metadata *MD) {
+    switch (MD->getMetadataID()) {
+    default:
+      return false;
+    case DIBasicTypeKind:
+    case DIDerivedTypeKind:
+    case DICompositeTypeKind:
+    case DISubroutineTypeKind:
+      return true;
+    }
+  }
+};
+
+/// Basic type, like 'int' or 'float'.
+///
+/// TODO: Split out DW_TAG_unspecified_type.
+/// TODO: Drop unused accessors.
+class DIBasicType : public DIType {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Encoding;
+
+  DIBasicType(LLVMContext &C, StorageType Storage, unsigned Tag,
+              uint64_t SizeInBits, uint32_t AlignInBits, unsigned Encoding,
+              ArrayRef<Metadata *> Ops)
+      : DIType(C, DIBasicTypeKind, Storage, Tag, 0, SizeInBits, AlignInBits, 0,
+               FlagZero, Ops),
+        Encoding(Encoding) {}
+  ~DIBasicType() = default;
+
+  static DIBasicType *getImpl(LLVMContext &Context, unsigned Tag,
+                              StringRef Name, uint64_t SizeInBits,
+                              uint32_t AlignInBits, unsigned Encoding,
+                              StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(Context, Tag, getCanonicalMDString(Context, Name),
+                   SizeInBits, AlignInBits, Encoding, Storage, ShouldCreate);
+  }
+  static DIBasicType *getImpl(LLVMContext &Context, unsigned Tag,
+                              MDString *Name, uint64_t SizeInBits,
+                              uint32_t AlignInBits, unsigned Encoding,
+                              StorageType Storage, bool ShouldCreate = true);
+
+  TempDIBasicType cloneImpl() const {
+    return getTemporary(getContext(), getTag(), getName(), getSizeInBits(),
+                        getAlignInBits(), getEncoding());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIBasicType, (unsigned Tag, StringRef Name),
+                    (Tag, Name, 0, 0, 0))
+  DEFINE_MDNODE_GET(DIBasicType,
+                    (unsigned Tag, StringRef Name, uint64_t SizeInBits,
+                     uint32_t AlignInBits, unsigned Encoding),
+                    (Tag, Name, SizeInBits, AlignInBits, Encoding))
+  DEFINE_MDNODE_GET(DIBasicType,
+                    (unsigned Tag, MDString *Name, uint64_t SizeInBits,
+                     uint32_t AlignInBits, unsigned Encoding),
+                    (Tag, Name, SizeInBits, AlignInBits, Encoding))
+
+  TempDIBasicType clone() const { return cloneImpl(); }
+
+  unsigned getEncoding() const { return Encoding; }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIBasicTypeKind;
+  }
+};
+
+/// Derived types.
+///
+/// This includes qualified types, pointers, references, friends, typedefs, and
+/// class members.
+///
+/// TODO: Split out members (inheritance, fields, methods, etc.).
+class DIDerivedType : public DIType {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  /// \brief The DWARF address space of the memory pointed to or referenced by a
+  /// pointer or reference type respectively.
+  Optional<unsigned> DWARFAddressSpace;
+
+  DIDerivedType(LLVMContext &C, StorageType Storage, unsigned Tag,
+                unsigned Line, uint64_t SizeInBits, uint32_t AlignInBits,
+                uint64_t OffsetInBits, Optional<unsigned> DWARFAddressSpace,
+                DIFlags Flags, ArrayRef<Metadata *> Ops)
+      : DIType(C, DIDerivedTypeKind, Storage, Tag, Line, SizeInBits,
+               AlignInBits, OffsetInBits, Flags, Ops),
+        DWARFAddressSpace(DWARFAddressSpace) {}
+  ~DIDerivedType() = default;
+
+  static DIDerivedType *getImpl(LLVMContext &Context, unsigned Tag,
+                                StringRef Name, DIFile *File, unsigned Line,
+                                DIScopeRef Scope, DITypeRef BaseType,
+                                uint64_t SizeInBits, uint32_t AlignInBits,
+                                uint64_t OffsetInBits,
+                                Optional<unsigned> DWARFAddressSpace,
+                                DIFlags Flags, Metadata *ExtraData,
+                                StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(Context, Tag, getCanonicalMDString(Context, Name), File,
+                   Line, Scope, BaseType, SizeInBits, AlignInBits, OffsetInBits,
+                   DWARFAddressSpace, Flags, ExtraData, Storage, ShouldCreate);
+  }
+  static DIDerivedType *getImpl(LLVMContext &Context, unsigned Tag,
+                                MDString *Name, Metadata *File, unsigned Line,
+                                Metadata *Scope, Metadata *BaseType,
+                                uint64_t SizeInBits, uint32_t AlignInBits,
+                                uint64_t OffsetInBits,
+                                Optional<unsigned> DWARFAddressSpace,
+                                DIFlags Flags, Metadata *ExtraData,
+                                StorageType Storage, bool ShouldCreate = true);
+
+  TempDIDerivedType cloneImpl() const {
+    return getTemporary(getContext(), getTag(), getName(), getFile(), getLine(),
+                        getScope(), getBaseType(), getSizeInBits(),
+                        getAlignInBits(), getOffsetInBits(),
+                        getDWARFAddressSpace(), getFlags(), getExtraData());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIDerivedType,
+                    (unsigned Tag, MDString *Name, Metadata *File,
+                     unsigned Line, Metadata *Scope, Metadata *BaseType,
+                     uint64_t SizeInBits, uint32_t AlignInBits,
+                     uint64_t OffsetInBits,
+                     Optional<unsigned> DWARFAddressSpace, DIFlags Flags,
+                     Metadata *ExtraData = nullptr),
+                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
+                     AlignInBits, OffsetInBits, DWARFAddressSpace, Flags,
+                     ExtraData))
+  DEFINE_MDNODE_GET(DIDerivedType,
+                    (unsigned Tag, StringRef Name, DIFile *File, unsigned Line,
+                     DIScopeRef Scope, DITypeRef BaseType, uint64_t SizeInBits,
+                     uint32_t AlignInBits, uint64_t OffsetInBits,
+                     Optional<unsigned> DWARFAddressSpace, DIFlags Flags,
+                     Metadata *ExtraData = nullptr),
+                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
+                     AlignInBits, OffsetInBits, DWARFAddressSpace, Flags,
+                     ExtraData))
+
+  TempDIDerivedType clone() const { return cloneImpl(); }
+
+  /// Get the base type this is derived from.
+  DITypeRef getBaseType() const { return DITypeRef(getRawBaseType()); }
+  Metadata *getRawBaseType() const { return getOperand(3); }
+
+  /// \returns The DWARF address space of the memory pointed to or referenced by
+  /// a pointer or reference type respectively.
+  Optional<unsigned> getDWARFAddressSpace() const { return DWARFAddressSpace; }
+
+  /// 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); }
+
+  /// Get casted version of extra data.
+  /// @{
+  DITypeRef getClassType() const {
+    assert(getTag() == dwarf::DW_TAG_ptr_to_member_type);
+    return DITypeRef(getExtraData());
+  }
+
+  DIObjCProperty *getObjCProperty() const {
+    return dyn_cast_or_null<DIObjCProperty>(getExtraData());
+  }
+
+  Constant *getStorageOffsetInBits() const {
+    assert(getTag() == dwarf::DW_TAG_member && isBitField());
+    if (auto *C = cast_or_null<ConstantAsMetadata>(getExtraData()))
+      return C->getValue();
+    return nullptr;
+  }
+
+  Constant *getConstant() const {
+    assert(getTag() == dwarf::DW_TAG_member && isStaticMember());
+    if (auto *C = cast_or_null<ConstantAsMetadata>(getExtraData()))
+      return C->getValue();
+    return nullptr;
+  }
+  Constant *getDiscriminantValue() const {
+    assert(getTag() == dwarf::DW_TAG_member && !isStaticMember());
+    if (auto *C = cast_or_null<ConstantAsMetadata>(getExtraData()))
+      return C->getValue();
+    return nullptr;
+  }
+  /// @}
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIDerivedTypeKind;
+  }
+};
+
+/// Composite types.
+///
+/// TODO: Detach from DerivedTypeBase (split out MDEnumType?).
+/// TODO: Create a custom, unrelated node for DW_TAG_array_type.
+class DICompositeType : public DIType {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned RuntimeLang;
+
+  DICompositeType(LLVMContext &C, StorageType Storage, unsigned Tag,
+                  unsigned Line, unsigned RuntimeLang, uint64_t SizeInBits,
+                  uint32_t AlignInBits, uint64_t OffsetInBits, DIFlags Flags,
+                  ArrayRef<Metadata *> Ops)
+      : DIType(C, DICompositeTypeKind, Storage, Tag, Line, SizeInBits,
+               AlignInBits, OffsetInBits, Flags, Ops),
+        RuntimeLang(RuntimeLang) {}
+  ~DICompositeType() = default;
+
+  /// Change fields in place.
+  void mutate(unsigned Tag, unsigned Line, unsigned RuntimeLang,
+              uint64_t SizeInBits, uint32_t AlignInBits,
+              uint64_t OffsetInBits, DIFlags Flags) {
+    assert(isDistinct() && "Only distinct nodes can mutate");
+    assert(getRawIdentifier() && "Only ODR-uniqued nodes should mutate");
+    this->RuntimeLang = RuntimeLang;
+    DIType::mutate(Tag, Line, SizeInBits, AlignInBits, OffsetInBits, Flags);
+  }
+
+  static DICompositeType *
+  getImpl(LLVMContext &Context, unsigned Tag, StringRef Name, Metadata *File,
+          unsigned Line, DIScopeRef Scope, DITypeRef BaseType,
+          uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
+          DIFlags Flags, DINodeArray Elements, unsigned RuntimeLang,
+          DITypeRef VTableHolder, DITemplateParameterArray TemplateParams,
+          StringRef Identifier, DIDerivedType *Discriminator,
+          StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(
+        Context, Tag, getCanonicalMDString(Context, Name), File, Line, Scope,
+        BaseType, SizeInBits, AlignInBits, OffsetInBits, Flags, Elements.get(),
+        RuntimeLang, VTableHolder, TemplateParams.get(),
+        getCanonicalMDString(Context, Identifier), Discriminator, Storage, ShouldCreate);
+  }
+  static DICompositeType *
+  getImpl(LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
+          unsigned Line, Metadata *Scope, Metadata *BaseType,
+          uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
+          DIFlags Flags, Metadata *Elements, unsigned RuntimeLang,
+          Metadata *VTableHolder, Metadata *TemplateParams,
+          MDString *Identifier, Metadata *Discriminator,
+          StorageType Storage, bool ShouldCreate = true);
+
+  TempDICompositeType cloneImpl() const {
+    return getTemporary(getContext(), getTag(), getName(), getFile(), getLine(),
+                        getScope(), getBaseType(), getSizeInBits(),
+                        getAlignInBits(), getOffsetInBits(), getFlags(),
+                        getElements(), getRuntimeLang(), getVTableHolder(),
+                        getTemplateParams(), getIdentifier(), getDiscriminator());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DICompositeType,
+                    (unsigned Tag, StringRef Name, DIFile *File, unsigned Line,
+                     DIScopeRef Scope, DITypeRef BaseType, uint64_t SizeInBits,
+                     uint32_t AlignInBits, uint64_t OffsetInBits,
+                     DIFlags Flags, DINodeArray Elements, unsigned RuntimeLang,
+                     DITypeRef VTableHolder,
+                     DITemplateParameterArray TemplateParams = nullptr,
+                     StringRef Identifier = "", DIDerivedType *Discriminator = nullptr),
+                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
+                     AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
+                     VTableHolder, TemplateParams, Identifier, Discriminator))
+  DEFINE_MDNODE_GET(DICompositeType,
+                    (unsigned Tag, MDString *Name, Metadata *File,
+                     unsigned Line, Metadata *Scope, Metadata *BaseType,
+                     uint64_t SizeInBits, uint32_t AlignInBits,
+                     uint64_t OffsetInBits, DIFlags Flags, Metadata *Elements,
+                     unsigned RuntimeLang, Metadata *VTableHolder,
+                     Metadata *TemplateParams = nullptr,
+                     MDString *Identifier = nullptr,
+                     Metadata *Discriminator = nullptr),
+                    (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
+                     AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
+                     VTableHolder, TemplateParams, Identifier, Discriminator))
+
+  TempDICompositeType clone() const { return cloneImpl(); }
+
+  /// Get a DICompositeType with the given ODR identifier.
+  ///
+  /// If \a LLVMContext::isODRUniquingDebugTypes(), gets the mapped
+  /// DICompositeType for the given ODR \c Identifier.  If none exists, creates
+  /// a new node.
+  ///
+  /// Else, returns \c nullptr.
+  static DICompositeType *
+  getODRType(LLVMContext &Context, MDString &Identifier, unsigned Tag,
+             MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
+             Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
+             uint64_t OffsetInBits, DIFlags Flags, Metadata *Elements,
+             unsigned RuntimeLang, Metadata *VTableHolder,
+             Metadata *TemplateParams, Metadata *Discriminator);
+  static DICompositeType *getODRTypeIfExists(LLVMContext &Context,
+                                             MDString &Identifier);
+
+  /// Build a DICompositeType with the given ODR identifier.
+  ///
+  /// Looks up the mapped DICompositeType for the given ODR \c Identifier.  If
+  /// it doesn't exist, creates a new one.  If it does exist and \a
+  /// isForwardDecl(), and the new arguments would be a definition, mutates the
+  /// the type in place.  In either case, returns the type.
+  ///
+  /// If not \a LLVMContext::isODRUniquingDebugTypes(), this function returns
+  /// nullptr.
+  static DICompositeType *
+  buildODRType(LLVMContext &Context, MDString &Identifier, unsigned Tag,
+               MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
+               Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
+               uint64_t OffsetInBits, DIFlags Flags, Metadata *Elements,
+               unsigned RuntimeLang, Metadata *VTableHolder,
+               Metadata *TemplateParams, Metadata *Discriminator);
+
+  DITypeRef getBaseType() const { return DITypeRef(getRawBaseType()); }
+  DINodeArray getElements() const {
+    return cast_or_null<MDTuple>(getRawElements());
+  }
+  DITypeRef getVTableHolder() const { return DITypeRef(getRawVTableHolder()); }
+  DITemplateParameterArray getTemplateParams() const {
+    return cast_or_null<MDTuple>(getRawTemplateParams());
+  }
+  StringRef getIdentifier() const { return getStringOperand(7); }
+  unsigned getRuntimeLang() const { return RuntimeLang; }
+
+  Metadata *getRawBaseType() const { return getOperand(3); }
+  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); }
+  Metadata *getRawDiscriminator() const { return getOperand(8); }
+  DIDerivedType *getDiscriminator() const { return getOperandAs<DIDerivedType>(8); }
+
+  /// 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(DINodeArray Elements) {
+#ifndef NDEBUG
+    for (DINode *Op : getElements())
+      assert(is_contained(Elements->operands(), Op) &&
+             "Lost a member during member list replacement");
+#endif
+    replaceOperandWith(4, Elements.get());
+  }
+
+  void replaceVTableHolder(DITypeRef VTableHolder) {
+    replaceOperandWith(5, VTableHolder);
+  }
+
+  void replaceTemplateParams(DITemplateParameterArray TemplateParams) {
+    replaceOperandWith(6, TemplateParams.get());
+  }
+  /// @}
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DICompositeTypeKind;
+  }
+};
+
+/// Type array for a subprogram.
+///
+/// TODO: Fold the array of types in directly as operands.
+class DISubroutineType : public DIType {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  /// The calling convention used with DW_AT_calling_convention. Actually of
+  /// type dwarf::CallingConvention.
+  uint8_t CC;
+
+  DISubroutineType(LLVMContext &C, StorageType Storage, DIFlags Flags,
+                   uint8_t CC, ArrayRef<Metadata *> Ops)
+      : DIType(C, DISubroutineTypeKind, Storage, dwarf::DW_TAG_subroutine_type,
+               0, 0, 0, 0, Flags, Ops),
+        CC(CC) {}
+  ~DISubroutineType() = default;
+
+  static DISubroutineType *getImpl(LLVMContext &Context, DIFlags Flags,
+                                   uint8_t CC, DITypeRefArray TypeArray,
+                                   StorageType Storage,
+                                   bool ShouldCreate = true) {
+    return getImpl(Context, Flags, CC, TypeArray.get(), Storage, ShouldCreate);
+  }
+  static DISubroutineType *getImpl(LLVMContext &Context, DIFlags Flags,
+                                   uint8_t CC, Metadata *TypeArray,
+                                   StorageType Storage,
+                                   bool ShouldCreate = true);
+
+  TempDISubroutineType cloneImpl() const {
+    return getTemporary(getContext(), getFlags(), getCC(), getTypeArray());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DISubroutineType,
+                    (DIFlags Flags, uint8_t CC, DITypeRefArray TypeArray),
+                    (Flags, CC, TypeArray))
+  DEFINE_MDNODE_GET(DISubroutineType,
+                    (DIFlags Flags, uint8_t CC, Metadata *TypeArray),
+                    (Flags, CC, TypeArray))
+
+  TempDISubroutineType clone() const { return cloneImpl(); }
+
+  uint8_t getCC() const { return CC; }
+
+  DITypeRefArray getTypeArray() const {
+    return cast_or_null<MDTuple>(getRawTypeArray());
+  }
+
+  Metadata *getRawTypeArray() const { return getOperand(3); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DISubroutineTypeKind;
+  }
+};
+
+/// Compile unit.
+class DICompileUnit : public DIScope {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+public:
+  enum DebugEmissionKind : unsigned {
+    NoDebug = 0,
+    FullDebug,
+    LineTablesOnly,
+    LastEmissionKind = LineTablesOnly
+  };
+
+  static Optional<DebugEmissionKind> getEmissionKind(StringRef Str);
+  static const char *EmissionKindString(DebugEmissionKind EK);
+
+private:
+  unsigned SourceLanguage;
+  bool IsOptimized;
+  unsigned RuntimeVersion;
+  unsigned EmissionKind;
+  uint64_t DWOId;
+  bool SplitDebugInlining;
+  bool DebugInfoForProfiling;
+  bool GnuPubnames;
+
+  DICompileUnit(LLVMContext &C, StorageType Storage, unsigned SourceLanguage,
+                bool IsOptimized, unsigned RuntimeVersion,
+                unsigned EmissionKind, uint64_t DWOId, bool SplitDebugInlining,
+                bool DebugInfoForProfiling, bool GnuPubnames, ArrayRef<Metadata *> Ops)
+      : DIScope(C, DICompileUnitKind, Storage, dwarf::DW_TAG_compile_unit, Ops),
+        SourceLanguage(SourceLanguage), IsOptimized(IsOptimized),
+        RuntimeVersion(RuntimeVersion), EmissionKind(EmissionKind),
+        DWOId(DWOId), SplitDebugInlining(SplitDebugInlining),
+        DebugInfoForProfiling(DebugInfoForProfiling), GnuPubnames(GnuPubnames) {
+    assert(Storage != Uniqued);
+  }
+  ~DICompileUnit() = default;
+
+  static DICompileUnit *
+  getImpl(LLVMContext &Context, unsigned SourceLanguage, DIFile *File,
+          StringRef Producer, bool IsOptimized, StringRef Flags,
+          unsigned RuntimeVersion, StringRef SplitDebugFilename,
+          unsigned EmissionKind, DICompositeTypeArray EnumTypes,
+          DIScopeArray RetainedTypes,
+          DIGlobalVariableExpressionArray GlobalVariables,
+          DIImportedEntityArray ImportedEntities, DIMacroNodeArray Macros,
+          uint64_t DWOId, bool SplitDebugInlining, bool DebugInfoForProfiling,
+          bool GnuPubnames, StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(
+        Context, SourceLanguage, File, getCanonicalMDString(Context, Producer),
+        IsOptimized, getCanonicalMDString(Context, Flags), RuntimeVersion,
+        getCanonicalMDString(Context, SplitDebugFilename), EmissionKind,
+        EnumTypes.get(), RetainedTypes.get(), GlobalVariables.get(),
+        ImportedEntities.get(), Macros.get(), DWOId, SplitDebugInlining,
+        DebugInfoForProfiling, GnuPubnames, Storage, ShouldCreate);
+  }
+  static DICompileUnit *
+  getImpl(LLVMContext &Context, unsigned SourceLanguage, Metadata *File,
+          MDString *Producer, bool IsOptimized, MDString *Flags,
+          unsigned RuntimeVersion, MDString *SplitDebugFilename,
+          unsigned EmissionKind, Metadata *EnumTypes, Metadata *RetainedTypes,
+          Metadata *GlobalVariables, Metadata *ImportedEntities,
+          Metadata *Macros, uint64_t DWOId, bool SplitDebugInlining,
+          bool DebugInfoForProfiling, bool GnuPubnames, StorageType Storage,
+          bool ShouldCreate = true);
+
+  TempDICompileUnit cloneImpl() const {
+    return getTemporary(getContext(), getSourceLanguage(), getFile(),
+                        getProducer(), isOptimized(), getFlags(),
+                        getRuntimeVersion(), getSplitDebugFilename(),
+                        getEmissionKind(), getEnumTypes(), getRetainedTypes(),
+                        getGlobalVariables(), getImportedEntities(),
+                        getMacros(), DWOId, getSplitDebugInlining(),
+                        getDebugInfoForProfiling(), getGnuPubnames());
+  }
+
+public:
+  static void get() = delete;
+  static void getIfExists() = delete;
+
+  DEFINE_MDNODE_GET_DISTINCT_TEMPORARY(
+      DICompileUnit,
+      (unsigned SourceLanguage, DIFile *File, StringRef Producer,
+       bool IsOptimized, StringRef Flags, unsigned RuntimeVersion,
+       StringRef SplitDebugFilename, DebugEmissionKind EmissionKind,
+       DICompositeTypeArray EnumTypes, DIScopeArray RetainedTypes,
+       DIGlobalVariableExpressionArray GlobalVariables,
+       DIImportedEntityArray ImportedEntities, DIMacroNodeArray Macros,
+       uint64_t DWOId, bool SplitDebugInlining, bool DebugInfoForProfiling,
+       bool GnuPubnames),
+      (SourceLanguage, File, Producer, IsOptimized, Flags, RuntimeVersion,
+       SplitDebugFilename, EmissionKind, EnumTypes, RetainedTypes,
+       GlobalVariables, ImportedEntities, Macros, DWOId, SplitDebugInlining,
+       DebugInfoForProfiling, GnuPubnames))
+  DEFINE_MDNODE_GET_DISTINCT_TEMPORARY(
+      DICompileUnit,
+      (unsigned SourceLanguage, Metadata *File, MDString *Producer,
+       bool IsOptimized, MDString *Flags, unsigned RuntimeVersion,
+       MDString *SplitDebugFilename, unsigned EmissionKind, Metadata *EnumTypes,
+       Metadata *RetainedTypes, Metadata *GlobalVariables,
+       Metadata *ImportedEntities, Metadata *Macros, uint64_t DWOId,
+       bool SplitDebugInlining, bool DebugInfoForProfiling, bool GnuPubnames),
+      (SourceLanguage, File, Producer, IsOptimized, Flags, RuntimeVersion,
+       SplitDebugFilename, EmissionKind, EnumTypes, RetainedTypes,
+       GlobalVariables, ImportedEntities, Macros, DWOId, SplitDebugInlining,
+       DebugInfoForProfiling, GnuPubnames))
+
+  TempDICompileUnit clone() const { return cloneImpl(); }
+
+  unsigned getSourceLanguage() const { return SourceLanguage; }
+  bool isOptimized() const { return IsOptimized; }
+  unsigned getRuntimeVersion() const { return RuntimeVersion; }
+  DebugEmissionKind getEmissionKind() const {
+    return (DebugEmissionKind)EmissionKind;
+  }
+  bool getDebugInfoForProfiling() const { return DebugInfoForProfiling; }
+  bool getGnuPubnames() const { return GnuPubnames; }
+  StringRef getProducer() const { return getStringOperand(1); }
+  StringRef getFlags() const { return getStringOperand(2); }
+  StringRef getSplitDebugFilename() const { return getStringOperand(3); }
+  DICompositeTypeArray getEnumTypes() const {
+    return cast_or_null<MDTuple>(getRawEnumTypes());
+  }
+  DIScopeArray getRetainedTypes() const {
+    return cast_or_null<MDTuple>(getRawRetainedTypes());
+  }
+  DIGlobalVariableExpressionArray getGlobalVariables() const {
+    return cast_or_null<MDTuple>(getRawGlobalVariables());
+  }
+  DIImportedEntityArray getImportedEntities() const {
+    return cast_or_null<MDTuple>(getRawImportedEntities());
+  }
+  DIMacroNodeArray getMacros() const {
+    return cast_or_null<MDTuple>(getRawMacros());
+  }
+  uint64_t getDWOId() const { return DWOId; }
+  void setDWOId(uint64_t DwoId) { DWOId = DwoId; }
+  bool getSplitDebugInlining() const { return SplitDebugInlining; }
+  void setSplitDebugInlining(bool SplitDebugInlining) {
+    this->SplitDebugInlining = SplitDebugInlining;
+  }
+
+  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 *getRawGlobalVariables() const { return getOperand(6); }
+  Metadata *getRawImportedEntities() const { return getOperand(7); }
+  Metadata *getRawMacros() const { return getOperand(8); }
+
+  /// 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
+  /// DICompileUnit should be fairly rare.
+  /// @{
+  void replaceEnumTypes(DICompositeTypeArray N) {
+    replaceOperandWith(4, N.get());
+  }
+  void replaceRetainedTypes(DITypeArray N) {
+    replaceOperandWith(5, N.get());
+  }
+  void replaceGlobalVariables(DIGlobalVariableExpressionArray N) {
+    replaceOperandWith(6, N.get());
+  }
+  void replaceImportedEntities(DIImportedEntityArray N) {
+    replaceOperandWith(7, N.get());
+  }
+  void replaceMacros(DIMacroNodeArray N) { replaceOperandWith(8, N.get()); }
+  /// @}
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DICompileUnitKind;
+  }
+};
+
+/// A scope for locals.
+///
+/// A legal scope for lexical blocks, local variables, and debug info
+/// locations.  Subclasses are \a DISubprogram, \a DILexicalBlock, and \a
+/// DILexicalBlockFile.
+class DILocalScope : public DIScope {
+protected:
+  DILocalScope(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Tag,
+               ArrayRef<Metadata *> Ops)
+      : DIScope(C, ID, Storage, Tag, Ops) {}
+  ~DILocalScope() = default;
+
+public:
+  /// Get the subprogram for this scope.
+  ///
+  /// Return this if it's an \a DISubprogram; otherwise, look up the scope
+  /// chain.
+  DISubprogram *getSubprogram() const;
+
+  /// Get the first non DILexicalBlockFile scope of this scope.
+  ///
+  /// Return this if it's not a \a DILexicalBlockFIle; otherwise, look up the
+  /// scope chain.
+  DILocalScope *getNonLexicalBlockFileScope() const;
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DISubprogramKind ||
+           MD->getMetadataID() == DILexicalBlockKind ||
+           MD->getMetadataID() == DILexicalBlockFileKind;
+  }
+};
+
+/// Debug location.
+///
+/// A debug location in source code, used for debug info and otherwise.
+class DILocation : public MDNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  DILocation(LLVMContext &C, StorageType Storage, unsigned Line,
+             unsigned Column, ArrayRef<Metadata *> MDs);
+  ~DILocation() { dropAllReferences(); }
+
+  static DILocation *getImpl(LLVMContext &Context, unsigned Line,
+                             unsigned Column, Metadata *Scope,
+                             Metadata *InlinedAt, StorageType Storage,
+                             bool ShouldCreate = true);
+  static DILocation *getImpl(LLVMContext &Context, unsigned Line,
+                             unsigned Column, DILocalScope *Scope,
+                             DILocation *InlinedAt, StorageType Storage,
+                             bool ShouldCreate = true) {
+    return getImpl(Context, Line, Column, static_cast<Metadata *>(Scope),
+                   static_cast<Metadata *>(InlinedAt), Storage, ShouldCreate);
+  }
+
+  /// With a given unsigned int \p U, use up to 13 bits to represent it.
+  /// old_bit 1~5  --> new_bit 1~5
+  /// old_bit 6~12 --> new_bit 7~13
+  /// new_bit_6 is 0 if higher bits (7~13) are all 0
+  static unsigned getPrefixEncodingFromUnsigned(unsigned U) {
+    U &= 0xfff;
+    return U > 0x1f ? (((U & 0xfe0) << 1) | (U & 0x1f) | 0x20) : U;
+  }
+
+  /// Reverse transformation as getPrefixEncodingFromUnsigned.
+  static unsigned getUnsignedFromPrefixEncoding(unsigned U) {
+    return (U & 0x20) ? (((U >> 1) & 0xfe0) | (U & 0x1f)) : (U & 0x1f);
+  }
+
+  /// Returns the next component stored in discriminator.
+  static unsigned getNextComponentInDiscriminator(unsigned D) {
+    if ((D & 1) == 0)
+      return D >> ((D & 0x40) ? 14 : 7);
+    else
+      return D >> 1;
+  }
+
+  TempDILocation cloneImpl() const {
+    // Get the raw scope/inlinedAt since it is possible to invoke this on
+    // a DILocation containing temporary metadata.
+    return getTemporary(getContext(), getLine(), getColumn(), getRawScope(),
+                        getRawInlinedAt());
+  }
+
+public:
+  // Disallow replacing operands.
+  void replaceOperandWith(unsigned I, Metadata *New) = delete;
+
+  DEFINE_MDNODE_GET(DILocation,
+                    (unsigned Line, unsigned Column, Metadata *Scope,
+                     Metadata *InlinedAt = nullptr),
+                    (Line, Column, Scope, InlinedAt))
+  DEFINE_MDNODE_GET(DILocation,
+                    (unsigned Line, unsigned Column, DILocalScope *Scope,
+                     DILocation *InlinedAt = nullptr),
+                    (Line, Column, Scope, InlinedAt))
+
+  /// Return a (temporary) clone of this.
+  TempDILocation clone() const { return cloneImpl(); }
+
+  unsigned getLine() const { return SubclassData32; }
+  unsigned getColumn() const { return SubclassData16; }
+  DILocalScope *getScope() const { return cast<DILocalScope>(getRawScope()); }
+
+  DILocation *getInlinedAt() const {
+    return cast_or_null<DILocation>(getRawInlinedAt());
+  }
+
+  DIFile *getFile() const { return getScope()->getFile(); }
+  StringRef getFilename() const { return getScope()->getFilename(); }
+  StringRef getDirectory() const { return getScope()->getDirectory(); }
+  Optional<StringRef> getSource() const { return getScope()->getSource(); }
+
+  /// Get the scope where this is inlined.
+  ///
+  /// Walk through \a getInlinedAt() and return \a getScope() from the deepest
+  /// location.
+  DILocalScope *getInlinedAtScope() const {
+    if (auto *IA = getInlinedAt())
+      return IA->getInlinedAtScope();
+    return getScope();
+  }
+
+  /// Check whether this can be discriminated from another location.
+  ///
+  /// Check \c this can be discriminated from \c RHS in a linetable entry.
+  /// Scope and inlined-at chains are not recorded in the linetable, so they
+  /// cannot be used to distinguish basic blocks.
+  bool canDiscriminate(const DILocation &RHS) const {
+    return getLine() != RHS.getLine() ||
+           getColumn() != RHS.getColumn() ||
+           getDiscriminator() != RHS.getDiscriminator() ||
+           getFilename() != RHS.getFilename() ||
+           getDirectory() != RHS.getDirectory();
+  }
+
+  /// Get the DWARF discriminator.
+  ///
+  /// DWARF discriminators distinguish identical file locations between
+  /// instructions that are on different basic blocks.
+  ///
+  /// There are 3 components stored in discriminator, from lower bits:
+  ///
+  /// Base discriminator: assigned by AddDiscriminators pass to identify IRs
+  ///                     that are defined by the same source line, but
+  ///                     different basic blocks.
+  /// Duplication factor: assigned by optimizations that will scale down
+  ///                     the execution frequency of the original IR.
+  /// Copy Identifier: assigned by optimizations that clones the IR.
+  ///                  Each copy of the IR will be assigned an identifier.
+  ///
+  /// Encoding:
+  ///
+  /// The above 3 components are encoded into a 32bit unsigned integer in
+  /// order. If the lowest bit is 1, the current component is empty, and the
+  /// next component will start in the next bit. Otherwise, the current
+  /// component is non-empty, and its content starts in the next bit. The
+  /// length of each components is either 5 bit or 12 bit: if the 7th bit
+  /// is 0, the bit 2~6 (5 bits) are used to represent the component; if the
+  /// 7th bit is 1, the bit 2~6 (5 bits) and 8~14 (7 bits) are combined to
+  /// represent the component.
+
+  inline unsigned getDiscriminator() const;
+
+  /// Returns a new DILocation with updated \p Discriminator.
+  inline const DILocation *cloneWithDiscriminator(unsigned Discriminator) const;
+
+  /// Returns a new DILocation with updated base discriminator \p BD.
+  inline const DILocation *setBaseDiscriminator(unsigned BD) const;
+
+  /// Returns the duplication factor stored in the discriminator.
+  inline unsigned getDuplicationFactor() const;
+
+  /// Returns the copy identifier stored in the discriminator.
+  inline unsigned getCopyIdentifier() const;
+
+  /// Returns the base discriminator stored in the discriminator.
+  inline unsigned getBaseDiscriminator() const;
+
+  /// Returns a new DILocation with duplication factor \p DF encoded in the
+  /// discriminator.
+  inline const DILocation *cloneWithDuplicationFactor(unsigned DF) const;
+
+  /// When two instructions are combined into a single instruction we also
+  /// need to combine the original locations into a single location.
+  ///
+  /// When the locations are the same we can use either location. When they
+  /// differ, we need a third location which is distinct from either. If
+  /// they have the same file/line but have a different discriminator we
+  /// could create a location with a new discriminator. If they are from
+  /// different files/lines the location is ambiguous and can't be
+  /// represented in a single line entry.  In this case, no location
+  /// should be set, unless the merged instruction is a call, which we will
+  /// set the merged debug location as line 0 of the nearest common scope
+  /// where 2 locations are inlined from. This only applies to Instruction;
+  /// for MachineInstruction, as it is post-inline, we will treat the call
+  /// instruction the same way as other instructions.
+  ///
+  /// \p ForInst: The Instruction the merged DILocation is for. If the
+  /// Instruction is unavailable or non-existent, use nullptr.
+  static const DILocation *
+  getMergedLocation(const DILocation *LocA, const DILocation *LocB,
+                    const Instruction *ForInst = nullptr);
+
+  /// Returns the base discriminator for a given encoded discriminator \p D.
+  static unsigned getBaseDiscriminatorFromDiscriminator(unsigned D) {
+    if ((D & 1) == 0)
+      return getUnsignedFromPrefixEncoding(D >> 1);
+    else
+      return 0;
+  }
+
+  /// Returns the duplication factor for a given encoded discriminator \p D.
+  static unsigned getDuplicationFactorFromDiscriminator(unsigned D) {
+    D = getNextComponentInDiscriminator(D);
+    if (D == 0 || (D & 1))
+      return 1;
+    else
+      return getUnsignedFromPrefixEncoding(D >> 1);
+  }
+
+  /// Returns the copy identifier for a given encoded discriminator \p D.
+  static unsigned getCopyIdentifierFromDiscriminator(unsigned D) {
+    return getUnsignedFromPrefixEncoding(getNextComponentInDiscriminator(
+        getNextComponentInDiscriminator(D)));
+  }
+
+
+  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() == DILocationKind;
+  }
+};
+
+/// Subprogram description.
+///
+/// TODO: Remove DisplayName.  It's always equal to Name.
+/// TODO: Split up flags.
+class DISubprogram : public DILocalScope {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+  unsigned ScopeLine;
+  unsigned VirtualIndex;
+
+  /// In the MS ABI, the implicit 'this' parameter is adjusted in the prologue
+  /// of method overrides from secondary bases by this amount. It may be
+  /// negative.
+  int ThisAdjustment;
+
+  // Virtuality can only assume three values, so we can pack
+  // in 2 bits (none/pure/pure_virtual).
+  unsigned Virtuality : 2;
+
+  // These are boolean flags so one bit is enough.
+  // MSVC starts a new container field every time the base
+  // type changes so we can't use 'bool' to ensure these bits
+  // are packed.
+  unsigned IsLocalToUnit : 1;
+  unsigned IsDefinition : 1;
+  unsigned IsOptimized : 1;
+
+  unsigned Padding : 3;
+
+  DIFlags Flags;
+
+  DISubprogram(LLVMContext &C, StorageType Storage, unsigned Line,
+               unsigned ScopeLine, unsigned Virtuality, unsigned VirtualIndex,
+               int ThisAdjustment, DIFlags Flags, bool IsLocalToUnit,
+               bool IsDefinition, bool IsOptimized, ArrayRef<Metadata *> Ops)
+      : DILocalScope(C, DISubprogramKind, Storage, dwarf::DW_TAG_subprogram,
+                     Ops),
+        Line(Line), ScopeLine(ScopeLine), VirtualIndex(VirtualIndex),
+        ThisAdjustment(ThisAdjustment), Virtuality(Virtuality),
+        IsLocalToUnit(IsLocalToUnit), IsDefinition(IsDefinition),
+        IsOptimized(IsOptimized), Flags(Flags) {
+    static_assert(dwarf::DW_VIRTUALITY_max < 4, "Virtuality out of range");
+    assert(Virtuality < 4 && "Virtuality out of range");
+  }
+  ~DISubprogram() = default;
+
+  static DISubprogram *
+  getImpl(LLVMContext &Context, DIScopeRef Scope, StringRef Name,
+          StringRef LinkageName, DIFile *File, unsigned Line,
+          DISubroutineType *Type, bool IsLocalToUnit, bool IsDefinition,
+          unsigned ScopeLine, DITypeRef ContainingType, unsigned Virtuality,
+          unsigned VirtualIndex, int ThisAdjustment, DIFlags Flags,
+          bool IsOptimized, DICompileUnit *Unit,
+          DITemplateParameterArray TemplateParams, DISubprogram *Declaration,
+          DILocalVariableArray Variables, DITypeArray ThrownTypes,
+          StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
+                   getCanonicalMDString(Context, LinkageName), File, Line, Type,
+                   IsLocalToUnit, IsDefinition, ScopeLine, ContainingType,
+                   Virtuality, VirtualIndex, ThisAdjustment, Flags, IsOptimized,
+                   Unit, TemplateParams.get(), Declaration, Variables.get(),
+                   ThrownTypes.get(), Storage, ShouldCreate);
+  }
+  static DISubprogram *
+  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,
+          int ThisAdjustment, DIFlags Flags, bool IsOptimized, Metadata *Unit,
+          Metadata *TemplateParams, Metadata *Declaration, Metadata *Variables,
+          Metadata *ThrownTypes, StorageType Storage, bool ShouldCreate = true);
+
+  TempDISubprogram cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getName(), getLinkageName(),
+                        getFile(), getLine(), getType(), isLocalToUnit(),
+                        isDefinition(), getScopeLine(), getContainingType(),
+                        getVirtuality(), getVirtualIndex(), getThisAdjustment(),
+                        getFlags(), isOptimized(), getUnit(),
+                        getTemplateParams(), getDeclaration(), getVariables(),
+                        getThrownTypes());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DISubprogram,
+                    (DIScopeRef Scope, StringRef Name, StringRef LinkageName,
+                     DIFile *File, unsigned Line, DISubroutineType *Type,
+                     bool IsLocalToUnit, bool IsDefinition, unsigned ScopeLine,
+                     DITypeRef ContainingType, unsigned Virtuality,
+                     unsigned VirtualIndex, int ThisAdjustment, DIFlags Flags,
+                     bool IsOptimized, DICompileUnit *Unit,
+                     DITemplateParameterArray TemplateParams = nullptr,
+                     DISubprogram *Declaration = nullptr,
+                     DILocalVariableArray Variables = nullptr,
+                     DITypeArray ThrownTypes = nullptr),
+                    (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
+                     IsDefinition, ScopeLine, ContainingType, Virtuality,
+                     VirtualIndex, ThisAdjustment, Flags, IsOptimized, Unit,
+                     TemplateParams, Declaration, Variables, ThrownTypes))
+  DEFINE_MDNODE_GET(
+      DISubprogram,
+      (Metadata * Scope, MDString *Name, MDString *LinkageName, Metadata *File,
+       unsigned Line, Metadata *Type, bool IsLocalToUnit, bool IsDefinition,
+       unsigned ScopeLine, Metadata *ContainingType, unsigned Virtuality,
+       unsigned VirtualIndex, int ThisAdjustment, DIFlags Flags,
+       bool IsOptimized, Metadata *Unit, Metadata *TemplateParams = nullptr,
+       Metadata *Declaration = nullptr, Metadata *Variables = nullptr,
+       Metadata *ThrownTypes = nullptr),
+      (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit, IsDefinition,
+       ScopeLine, ContainingType, Virtuality, VirtualIndex, ThisAdjustment,
+       Flags, IsOptimized, Unit, TemplateParams, Declaration, Variables,
+       ThrownTypes))
+
+  TempDISubprogram clone() const { return cloneImpl(); }
+
+public:
+  unsigned getLine() const { return Line; }
+  unsigned getVirtuality() const { return Virtuality; }
+  unsigned getVirtualIndex() const { return VirtualIndex; }
+  int getThisAdjustment() const { return ThisAdjustment; }
+  unsigned getScopeLine() const { return ScopeLine; }
+  DIFlags getFlags() const { return Flags; }
+  bool isLocalToUnit() const { return IsLocalToUnit; }
+  bool isDefinition() const { return IsDefinition; }
+  bool isOptimized() const { return IsOptimized; }
+
+  bool isArtificial() const { return getFlags() & FlagArtificial; }
+  bool isPrivate() const {
+    return (getFlags() & FlagAccessibility) == FlagPrivate;
+  }
+  bool isProtected() const {
+    return (getFlags() & FlagAccessibility) == FlagProtected;
+  }
+  bool isPublic() const {
+    return (getFlags() & FlagAccessibility) == FlagPublic;
+  }
+  bool isExplicit() const { return getFlags() & FlagExplicit; }
+  bool isPrototyped() const { return getFlags() & FlagPrototyped; }
+  bool isMainSubprogram() const { return getFlags() & FlagMainSubprogram; }
+
+  /// Check if this is reference-qualified.
+  ///
+  /// Return true if this subprogram is a C++11 reference-qualified non-static
+  /// member function (void foo() &).
+  bool isLValueReference() const { return getFlags() & FlagLValueReference; }
+
+  /// Check if this is rvalue-reference-qualified.
+  ///
+  /// Return true if this subprogram is a C++11 rvalue-reference-qualified
+  /// non-static member function (void foo() &&).
+  bool isRValueReference() const { return getFlags() & FlagRValueReference; }
+
+  /// Check if this is marked as noreturn.
+  ///
+  /// Return true if this subprogram is C++11 noreturn or C11 _Noreturn
+  bool isNoReturn() const { return getFlags() & FlagNoReturn; }
+
+  DIScopeRef getScope() const { return DIScopeRef(getRawScope()); }
+
+  StringRef getName() const { return getStringOperand(2); }
+  StringRef getLinkageName() const { return getStringOperand(3); }
+
+  DISubroutineType *getType() const {
+    return cast_or_null<DISubroutineType>(getRawType());
+  }
+  DITypeRef getContainingType() const {
+    return DITypeRef(getRawContainingType());
+  }
+
+  DICompileUnit *getUnit() const {
+    return cast_or_null<DICompileUnit>(getRawUnit());
+  }
+  void replaceUnit(DICompileUnit *CU) { replaceOperandWith(5, CU); }
+  DITemplateParameterArray getTemplateParams() const {
+    return cast_or_null<MDTuple>(getRawTemplateParams());
+  }
+  DISubprogram *getDeclaration() const {
+    return cast_or_null<DISubprogram>(getRawDeclaration());
+  }
+  DILocalVariableArray getVariables() const {
+    return cast_or_null<MDTuple>(getRawVariables());
+  }
+  DITypeArray getThrownTypes() const {
+    return cast_or_null<MDTuple>(getRawThrownTypes());
+  }
+
+  Metadata *getRawScope() const { return getOperand(1); }
+  MDString *getRawName() const { return getOperandAs<MDString>(2); }
+  MDString *getRawLinkageName() const { return getOperandAs<MDString>(3); }
+  Metadata *getRawType() const { return getOperand(4); }
+  Metadata *getRawUnit() const { return getOperand(5); }
+  Metadata *getRawDeclaration() const { return getOperand(6); }
+  Metadata *getRawVariables() const { return getOperand(7); }
+  Metadata *getRawContainingType() const {
+    return getNumOperands() > 8 ? getOperandAs<Metadata>(8) : nullptr;
+  }
+  Metadata *getRawTemplateParams() const {
+    return getNumOperands() > 9 ? getOperandAs<Metadata>(9) : nullptr;
+  }
+  Metadata *getRawThrownTypes() const {
+    return getNumOperands() > 10 ? getOperandAs<Metadata>(10) : nullptr;
+  }
+
+  /// Check if this subprogram describes the given function.
+  ///
+  /// FIXME: Should this be looking through bitcasts?
+  bool describes(const Function *F) const;
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DISubprogramKind;
+  }
+};
+
+class DILexicalBlockBase : public DILocalScope {
+protected:
+  DILexicalBlockBase(LLVMContext &C, unsigned ID, StorageType Storage,
+                     ArrayRef<Metadata *> Ops)
+      : DILocalScope(C, ID, Storage, dwarf::DW_TAG_lexical_block, Ops) {}
+  ~DILexicalBlockBase() = default;
+
+public:
+  DILocalScope *getScope() const { return cast<DILocalScope>(getRawScope()); }
+
+  Metadata *getRawScope() const { return getOperand(1); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DILexicalBlockKind ||
+           MD->getMetadataID() == DILexicalBlockFileKind;
+  }
+};
+
+class DILexicalBlock : public DILexicalBlockBase {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+  uint16_t Column;
+
+  DILexicalBlock(LLVMContext &C, StorageType Storage, unsigned Line,
+                 unsigned Column, ArrayRef<Metadata *> Ops)
+      : DILexicalBlockBase(C, DILexicalBlockKind, Storage, Ops), Line(Line),
+        Column(Column) {
+    assert(Column < (1u << 16) && "Expected 16-bit column");
+  }
+  ~DILexicalBlock() = default;
+
+  static DILexicalBlock *getImpl(LLVMContext &Context, DILocalScope *Scope,
+                                 DIFile *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 DILexicalBlock *getImpl(LLVMContext &Context, Metadata *Scope,
+                                 Metadata *File, unsigned Line, unsigned Column,
+                                 StorageType Storage, bool ShouldCreate = true);
+
+  TempDILexicalBlock cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getFile(), getLine(),
+                        getColumn());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DILexicalBlock, (DILocalScope * Scope, DIFile *File,
+                                     unsigned Line, unsigned Column),
+                    (Scope, File, Line, Column))
+  DEFINE_MDNODE_GET(DILexicalBlock, (Metadata * Scope, Metadata *File,
+                                     unsigned Line, unsigned Column),
+                    (Scope, File, Line, Column))
+
+  TempDILexicalBlock clone() const { return cloneImpl(); }
+
+  unsigned getLine() const { return Line; }
+  unsigned getColumn() const { return Column; }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DILexicalBlockKind;
+  }
+};
+
+class DILexicalBlockFile : public DILexicalBlockBase {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Discriminator;
+
+  DILexicalBlockFile(LLVMContext &C, StorageType Storage,
+                     unsigned Discriminator, ArrayRef<Metadata *> Ops)
+      : DILexicalBlockBase(C, DILexicalBlockFileKind, Storage, Ops),
+        Discriminator(Discriminator) {}
+  ~DILexicalBlockFile() = default;
+
+  static DILexicalBlockFile *getImpl(LLVMContext &Context, DILocalScope *Scope,
+                                     DIFile *File, unsigned Discriminator,
+                                     StorageType Storage,
+                                     bool ShouldCreate = true) {
+    return getImpl(Context, static_cast<Metadata *>(Scope),
+                   static_cast<Metadata *>(File), Discriminator, Storage,
+                   ShouldCreate);
+  }
+
+  static DILexicalBlockFile *getImpl(LLVMContext &Context, Metadata *Scope,
+                                     Metadata *File, unsigned Discriminator,
+                                     StorageType Storage,
+                                     bool ShouldCreate = true);
+
+  TempDILexicalBlockFile cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getFile(),
+                        getDiscriminator());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DILexicalBlockFile, (DILocalScope * Scope, DIFile *File,
+                                         unsigned Discriminator),
+                    (Scope, File, Discriminator))
+  DEFINE_MDNODE_GET(DILexicalBlockFile,
+                    (Metadata * Scope, Metadata *File, unsigned Discriminator),
+                    (Scope, File, Discriminator))
+
+  TempDILexicalBlockFile clone() const { return cloneImpl(); }
+
+  // TODO: Remove these once they're gone from DILexicalBlockBase.
+  unsigned getLine() const = delete;
+  unsigned getColumn() const = delete;
+
+  unsigned getDiscriminator() const { return Discriminator; }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DILexicalBlockFileKind;
+  }
+};
+
+unsigned DILocation::getDiscriminator() const {
+  if (auto *F = dyn_cast<DILexicalBlockFile>(getScope()))
+    return F->getDiscriminator();
+  return 0;
+}
+
+const DILocation *
+DILocation::cloneWithDiscriminator(unsigned Discriminator) const {
+  DIScope *Scope = getScope();
+  // Skip all parent DILexicalBlockFile that already have a discriminator
+  // assigned. We do not want to have nested DILexicalBlockFiles that have
+  // mutliple discriminators because only the leaf DILexicalBlockFile's
+  // dominator will be used.
+  for (auto *LBF = dyn_cast<DILexicalBlockFile>(Scope);
+       LBF && LBF->getDiscriminator() != 0;
+       LBF = dyn_cast<DILexicalBlockFile>(Scope))
+    Scope = LBF->getScope();
+  DILexicalBlockFile *NewScope =
+      DILexicalBlockFile::get(getContext(), Scope, getFile(), Discriminator);
+  return DILocation::get(getContext(), getLine(), getColumn(), NewScope,
+                         getInlinedAt());
+}
+
+unsigned DILocation::getBaseDiscriminator() const {
+  return getBaseDiscriminatorFromDiscriminator(getDiscriminator());
+}
+
+unsigned DILocation::getDuplicationFactor() const {
+  return getDuplicationFactorFromDiscriminator(getDiscriminator());
+}
+
+unsigned DILocation::getCopyIdentifier() const {
+  return getCopyIdentifierFromDiscriminator(getDiscriminator());
+}
+
+const DILocation *DILocation::setBaseDiscriminator(unsigned D) const {
+  if (D == 0)
+    return this;
+  else
+    return cloneWithDiscriminator(getPrefixEncodingFromUnsigned(D) << 1);
+}
+
+const DILocation *DILocation::cloneWithDuplicationFactor(unsigned DF) const {
+  DF *= getDuplicationFactor();
+  if (DF <= 1)
+    return this;
+
+  unsigned BD = getBaseDiscriminator();
+  unsigned CI = getCopyIdentifier() << (DF > 0x1f ? 14 : 7);
+  unsigned D = CI | (getPrefixEncodingFromUnsigned(DF) << 1);
+
+  if (BD == 0)
+    D = (D << 1) | 1;
+  else
+    D = (D << (BD > 0x1f ? 14 : 7)) | (getPrefixEncodingFromUnsigned(BD) << 1);
+
+  return cloneWithDiscriminator(D);
+}
+
+class DINamespace : public DIScope {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned ExportSymbols : 1;
+
+  DINamespace(LLVMContext &Context, StorageType Storage, bool ExportSymbols,
+              ArrayRef<Metadata *> Ops)
+      : DIScope(Context, DINamespaceKind, Storage, dwarf::DW_TAG_namespace,
+                Ops),
+        ExportSymbols(ExportSymbols) {}
+  ~DINamespace() = default;
+
+  static DINamespace *getImpl(LLVMContext &Context, DIScope *Scope,
+                              StringRef Name, bool ExportSymbols,
+                              StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
+                   ExportSymbols, Storage, ShouldCreate);
+  }
+  static DINamespace *getImpl(LLVMContext &Context, Metadata *Scope,
+                              MDString *Name, bool ExportSymbols,
+                              StorageType Storage, bool ShouldCreate = true);
+
+  TempDINamespace cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getName(),
+                        getExportSymbols());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DINamespace,
+                    (DIScope *Scope, StringRef Name, bool ExportSymbols),
+                    (Scope, Name, ExportSymbols))
+  DEFINE_MDNODE_GET(DINamespace,
+                    (Metadata *Scope, MDString *Name, bool ExportSymbols),
+                    (Scope, Name, ExportSymbols))
+
+  TempDINamespace clone() const { return cloneImpl(); }
+
+  bool getExportSymbols() const { return ExportSymbols; }
+  DIScope *getScope() const { return cast_or_null<DIScope>(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() == DINamespaceKind;
+  }
+};
+
+/// A (clang) module that has been imported by the compile unit.
+///
+class DIModule : public DIScope {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  DIModule(LLVMContext &Context, StorageType Storage, ArrayRef<Metadata *> Ops)
+      : DIScope(Context, DIModuleKind, Storage, dwarf::DW_TAG_module, Ops) {}
+  ~DIModule() = default;
+
+  static DIModule *getImpl(LLVMContext &Context, DIScope *Scope,
+                           StringRef Name, StringRef ConfigurationMacros,
+                           StringRef IncludePath, StringRef ISysRoot,
+                           StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
+                   getCanonicalMDString(Context, ConfigurationMacros),
+                   getCanonicalMDString(Context, IncludePath),
+                   getCanonicalMDString(Context, ISysRoot),
+                   Storage, ShouldCreate);
+  }
+  static DIModule *getImpl(LLVMContext &Context, Metadata *Scope,
+                           MDString *Name, MDString *ConfigurationMacros,
+                           MDString *IncludePath, MDString *ISysRoot,
+                           StorageType Storage, bool ShouldCreate = true);
+
+  TempDIModule cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getName(),
+                        getConfigurationMacros(), getIncludePath(),
+                        getISysRoot());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIModule, (DIScope *Scope, StringRef Name,
+                               StringRef ConfigurationMacros, StringRef IncludePath,
+                               StringRef ISysRoot),
+                    (Scope, Name, ConfigurationMacros, IncludePath, ISysRoot))
+  DEFINE_MDNODE_GET(DIModule,
+                    (Metadata *Scope, MDString *Name, MDString *ConfigurationMacros,
+                     MDString *IncludePath, MDString *ISysRoot),
+                    (Scope, Name, ConfigurationMacros, IncludePath, ISysRoot))
+
+  TempDIModule clone() const { return cloneImpl(); }
+
+  DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
+  StringRef getName() const { return getStringOperand(1); }
+  StringRef getConfigurationMacros() const { return getStringOperand(2); }
+  StringRef getIncludePath() const { return getStringOperand(3); }
+  StringRef getISysRoot() const { return getStringOperand(4); }
+
+  Metadata *getRawScope() const { return getOperand(0); }
+  MDString *getRawName() const { return getOperandAs<MDString>(1); }
+  MDString *getRawConfigurationMacros() const { return getOperandAs<MDString>(2); }
+  MDString *getRawIncludePath() const { return getOperandAs<MDString>(3); }
+  MDString *getRawISysRoot() const { return getOperandAs<MDString>(4); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIModuleKind;
+  }
+};
+
+/// Base class for template parameters.
+class DITemplateParameter : public DINode {
+protected:
+  DITemplateParameter(LLVMContext &Context, unsigned ID, StorageType Storage,
+                      unsigned Tag, ArrayRef<Metadata *> Ops)
+      : DINode(Context, ID, Storage, Tag, Ops) {}
+  ~DITemplateParameter() = default;
+
+public:
+  StringRef getName() const { return getStringOperand(0); }
+  DITypeRef getType() const { return DITypeRef(getRawType()); }
+
+  MDString *getRawName() const { return getOperandAs<MDString>(0); }
+  Metadata *getRawType() const { return getOperand(1); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DITemplateTypeParameterKind ||
+           MD->getMetadataID() == DITemplateValueParameterKind;
+  }
+};
+
+class DITemplateTypeParameter : public DITemplateParameter {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  DITemplateTypeParameter(LLVMContext &Context, StorageType Storage,
+                          ArrayRef<Metadata *> Ops)
+      : DITemplateParameter(Context, DITemplateTypeParameterKind, Storage,
+                            dwarf::DW_TAG_template_type_parameter, Ops) {}
+  ~DITemplateTypeParameter() = default;
+
+  static DITemplateTypeParameter *getImpl(LLVMContext &Context, StringRef Name,
+                                          DITypeRef Type, StorageType Storage,
+                                          bool ShouldCreate = true) {
+    return getImpl(Context, getCanonicalMDString(Context, Name), Type, Storage,
+                   ShouldCreate);
+  }
+  static DITemplateTypeParameter *getImpl(LLVMContext &Context, MDString *Name,
+                                          Metadata *Type, StorageType Storage,
+                                          bool ShouldCreate = true);
+
+  TempDITemplateTypeParameter cloneImpl() const {
+    return getTemporary(getContext(), getName(), getType());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DITemplateTypeParameter, (StringRef Name, DITypeRef Type),
+                    (Name, Type))
+  DEFINE_MDNODE_GET(DITemplateTypeParameter, (MDString * Name, Metadata *Type),
+                    (Name, Type))
+
+  TempDITemplateTypeParameter clone() const { return cloneImpl(); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DITemplateTypeParameterKind;
+  }
+};
+
+class DITemplateValueParameter : public DITemplateParameter {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  DITemplateValueParameter(LLVMContext &Context, StorageType Storage,
+                           unsigned Tag, ArrayRef<Metadata *> Ops)
+      : DITemplateParameter(Context, DITemplateValueParameterKind, Storage, Tag,
+                            Ops) {}
+  ~DITemplateValueParameter() = default;
+
+  static DITemplateValueParameter *getImpl(LLVMContext &Context, unsigned Tag,
+                                           StringRef Name, DITypeRef Type,
+                                           Metadata *Value, StorageType Storage,
+                                           bool ShouldCreate = true) {
+    return getImpl(Context, Tag, getCanonicalMDString(Context, Name), Type,
+                   Value, Storage, ShouldCreate);
+  }
+  static DITemplateValueParameter *getImpl(LLVMContext &Context, unsigned Tag,
+                                           MDString *Name, Metadata *Type,
+                                           Metadata *Value, StorageType Storage,
+                                           bool ShouldCreate = true);
+
+  TempDITemplateValueParameter cloneImpl() const {
+    return getTemporary(getContext(), getTag(), getName(), getType(),
+                        getValue());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DITemplateValueParameter, (unsigned Tag, StringRef Name,
+                                               DITypeRef Type, Metadata *Value),
+                    (Tag, Name, Type, Value))
+  DEFINE_MDNODE_GET(DITemplateValueParameter, (unsigned Tag, MDString *Name,
+                                               Metadata *Type, Metadata *Value),
+                    (Tag, Name, Type, Value))
+
+  TempDITemplateValueParameter clone() const { return cloneImpl(); }
+
+  Metadata *getValue() const { return getOperand(2); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DITemplateValueParameterKind;
+  }
+};
+
+/// Base class for variables.
+class DIVariable : public DINode {
+  unsigned Line;
+  uint32_t AlignInBits;
+
+protected:
+  DIVariable(LLVMContext &C, unsigned ID, StorageType Storage, unsigned Line,
+             ArrayRef<Metadata *> Ops, uint32_t AlignInBits = 0)
+      : DINode(C, ID, Storage, dwarf::DW_TAG_variable, Ops), Line(Line),
+        AlignInBits(AlignInBits) {}
+  ~DIVariable() = default;
+
+public:
+  unsigned getLine() const { return Line; }
+  DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
+  StringRef getName() const { return getStringOperand(1); }
+  DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
+  DITypeRef getType() const { return DITypeRef(getRawType()); }
+  uint32_t getAlignInBits() const { return AlignInBits; }
+  uint32_t getAlignInBytes() const { return getAlignInBits() / CHAR_BIT; }
+  /// Determines the size of the variable's type.
+  Optional<uint64_t> getSizeInBits() const;
+
+  StringRef getFilename() const {
+    if (auto *F = getFile())
+      return F->getFilename();
+    return "";
+  }
+
+  StringRef getDirectory() const {
+    if (auto *F = getFile())
+      return F->getDirectory();
+    return "";
+  }
+
+  Optional<StringRef> getSource() const {
+    if (auto *F = getFile())
+      return F->getSource();
+    return None;
+  }
+
+  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() == DILocalVariableKind ||
+           MD->getMetadataID() == DIGlobalVariableKind;
+  }
+};
+
+/// DWARF expression.
+///
+/// This is (almost) a DWARF expression that modifies the location of a
+/// variable, or the location of a single piece of a variable, or (when using
+/// DW_OP_stack_value) is the constant variable value.
+///
+/// TODO: Co-allocate the expression elements.
+/// TODO: Separate from MDNode, or otherwise drop Distinct and Temporary
+/// storage types.
+class DIExpression : public MDNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  std::vector<uint64_t> Elements;
+
+  DIExpression(LLVMContext &C, StorageType Storage, ArrayRef<uint64_t> Elements)
+      : MDNode(C, DIExpressionKind, Storage, None),
+        Elements(Elements.begin(), Elements.end()) {}
+  ~DIExpression() = default;
+
+  static DIExpression *getImpl(LLVMContext &Context,
+                               ArrayRef<uint64_t> Elements, StorageType Storage,
+                               bool ShouldCreate = true);
+
+  TempDIExpression cloneImpl() const {
+    return getTemporary(getContext(), getElements());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIExpression, (ArrayRef<uint64_t> Elements), (Elements))
+
+  TempDIExpression 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];
+  }
+
+  /// Determine whether this represents a standalone constant value.
+  bool isConstant() const;
+
+  using element_iterator = ArrayRef<uint64_t>::iterator;
+
+  element_iterator elements_begin() const { return getElements().begin(); }
+  element_iterator elements_end() const { return getElements().end(); }
+
+  /// A lightweight wrapper around an expression operand.
+  ///
+  /// TODO: Store arguments directly and change \a DIExpression to store a
+  /// range of these.
+  class ExprOperand {
+    const uint64_t *Op = nullptr;
+
+  public:
+    ExprOperand() = default;
+    explicit ExprOperand(const uint64_t *Op) : Op(Op) {}
+
+    const uint64_t *get() const { return Op; }
+
+    /// Get the operand code.
+    uint64_t getOp() const { return *Op; }
+
+    /// 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; }
+
+    /// Return the size of the operand.
+    ///
+    /// Return the number of elements in the operand (1 + args).
+    unsigned getSize() const;
+  };
+
+  /// An iterator for expression operands.
+  class expr_op_iterator
+      : public std::iterator<std::input_iterator_tag, ExprOperand> {
+    ExprOperand Op;
+
+  public:
+    expr_op_iterator() = default;
+    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;
+    }
+
+    /// Get the next iterator.
+    ///
+    /// \a std::next() doesn't work because this is technically an
+    /// input_iterator, but it's a perfectly valid operation.  This is an
+    /// accessor to provide the same functionality.
+    expr_op_iterator getNext() const { return ++expr_op_iterator(*this); }
+
+    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()); }
+  };
+
+  /// 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());
+  }
+  iterator_range<expr_op_iterator> expr_ops() const {
+    return {expr_op_begin(), expr_op_end()};
+  }
+  /// @}
+
+  bool isValid() const;
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIExpressionKind;
+  }
+
+  /// Return whether the first element a DW_OP_deref.
+  bool startsWithDeref() const {
+    return getNumElements() > 0 && getElement(0) == dwarf::DW_OP_deref;
+  }
+
+  /// Holds the characteristics of one fragment of a larger variable.
+  struct FragmentInfo {
+    uint64_t SizeInBits;
+    uint64_t OffsetInBits;
+  };
+
+  /// Retrieve the details of this fragment expression.
+  static Optional<FragmentInfo> getFragmentInfo(expr_op_iterator Start,
+                                                expr_op_iterator End);
+
+  /// Retrieve the details of this fragment expression.
+  Optional<FragmentInfo> getFragmentInfo() const {
+    return getFragmentInfo(expr_op_begin(), expr_op_end());
+  }
+
+  /// Return whether this is a piece of an aggregate variable.
+  bool isFragment() const { return getFragmentInfo().hasValue(); }
+
+  /// Append \p Ops with operations to apply the \p Offset.
+  static void appendOffset(SmallVectorImpl<uint64_t> &Ops, int64_t Offset);
+
+  /// If this is a constant offset, extract it. If there is no expression,
+  /// return true with an offset of zero.
+  bool extractIfOffset(int64_t &Offset) const;
+
+  /// Constants for DIExpression::prepend.
+  enum { NoDeref = false, WithDeref = true, WithStackValue = true };
+
+  /// Prepend \p DIExpr with a deref and offset operation and optionally turn it
+  /// into a stack value.
+  static DIExpression *prepend(const DIExpression *DIExpr, bool DerefBefore,
+                               int64_t Offset = 0, bool DerefAfter = false,
+                               bool StackValue = false);
+
+  /// Prepend \p DIExpr with the given opcodes and optionally turn it into a
+  /// stack value.
+  static DIExpression *doPrepend(const DIExpression *DIExpr,
+                                 SmallVectorImpl<uint64_t> &Ops,
+                                 bool StackValue = false);
+
+  /// Create a DIExpression to describe one part of an aggregate variable that
+  /// is fragmented across multiple Values. The DW_OP_LLVM_fragment operation
+  /// will be appended to the elements of \c Expr. If \c Expr already contains
+  /// a \c DW_OP_LLVM_fragment \c OffsetInBits is interpreted as an offset
+  /// into the existing fragment.
+  ///
+  /// \param OffsetInBits Offset of the piece in bits.
+  /// \param SizeInBits   Size of the piece in bits.
+  /// \return             Creating a fragment expression may fail if \c Expr
+  ///                     contains arithmetic operations that would be truncated.
+  static Optional<DIExpression *>
+  createFragmentExpression(const DIExpression *Expr, unsigned OffsetInBits,
+                           unsigned SizeInBits);
+
+  /// Determine the relative position of the fragments described by this
+  /// DIExpression and \p Other.
+  /// Returns -1 if this is entirely before Other, 0 if this and Other overlap,
+  /// 1 if this is entirely after Other.
+  int fragmentCmp(const DIExpression *Other) const {
+    auto Fragment1 = *getFragmentInfo();
+    auto Fragment2 = *Other->getFragmentInfo();
+    unsigned l1 = Fragment1.OffsetInBits;
+    unsigned l2 = Fragment2.OffsetInBits;
+    unsigned r1 = l1 + Fragment1.SizeInBits;
+    unsigned r2 = l2 + Fragment2.SizeInBits;
+    if (r1 <= l2)
+      return -1;
+    else if (r2 <= l1)
+      return 1;
+    else
+      return 0;
+  }
+
+  /// Check if fragments overlap between this DIExpression and \p Other.
+  bool fragmentsOverlap(const DIExpression *Other) const {
+    if (!isFragment() || !Other->isFragment())
+      return true;
+    return fragmentCmp(Other) == 0;
+  }
+};
+
+/// Global variables.
+///
+/// TODO: Remove DisplayName.  It's always equal to Name.
+class DIGlobalVariable : public DIVariable {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  bool IsLocalToUnit;
+  bool IsDefinition;
+
+  DIGlobalVariable(LLVMContext &C, StorageType Storage, unsigned Line,
+                   bool IsLocalToUnit, bool IsDefinition, uint32_t AlignInBits,
+                   ArrayRef<Metadata *> Ops)
+      : DIVariable(C, DIGlobalVariableKind, Storage, Line, Ops, AlignInBits),
+        IsLocalToUnit(IsLocalToUnit), IsDefinition(IsDefinition) {}
+  ~DIGlobalVariable() = default;
+
+  static DIGlobalVariable *getImpl(LLVMContext &Context, DIScope *Scope,
+                                   StringRef Name, StringRef LinkageName,
+                                   DIFile *File, unsigned Line, DITypeRef Type,
+                                   bool IsLocalToUnit, bool IsDefinition,
+                                   DIDerivedType *StaticDataMemberDeclaration,
+                                   uint32_t AlignInBits, StorageType Storage,
+                                   bool ShouldCreate = true) {
+    return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
+                   getCanonicalMDString(Context, LinkageName), File, Line, Type,
+                   IsLocalToUnit, IsDefinition, StaticDataMemberDeclaration,
+                   AlignInBits, Storage, ShouldCreate);
+  }
+  static DIGlobalVariable *
+  getImpl(LLVMContext &Context, Metadata *Scope, MDString *Name,
+          MDString *LinkageName, Metadata *File, unsigned Line, Metadata *Type,
+          bool IsLocalToUnit, bool IsDefinition,
+          Metadata *StaticDataMemberDeclaration, uint32_t AlignInBits,
+          StorageType Storage, bool ShouldCreate = true);
+
+  TempDIGlobalVariable cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getName(), getLinkageName(),
+                        getFile(), getLine(), getType(), isLocalToUnit(),
+                        isDefinition(), getStaticDataMemberDeclaration(),
+                        getAlignInBits());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIGlobalVariable,
+                    (DIScope * Scope, StringRef Name, StringRef LinkageName,
+                     DIFile *File, unsigned Line, DITypeRef Type,
+                     bool IsLocalToUnit, bool IsDefinition,
+                     DIDerivedType *StaticDataMemberDeclaration,
+                     uint32_t AlignInBits),
+                    (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
+                     IsDefinition, StaticDataMemberDeclaration, AlignInBits))
+  DEFINE_MDNODE_GET(DIGlobalVariable,
+                    (Metadata * Scope, MDString *Name, MDString *LinkageName,
+                     Metadata *File, unsigned Line, Metadata *Type,
+                     bool IsLocalToUnit, bool IsDefinition,
+                     Metadata *StaticDataMemberDeclaration,
+                     uint32_t AlignInBits),
+                    (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
+                     IsDefinition, StaticDataMemberDeclaration, AlignInBits))
+
+  TempDIGlobalVariable 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); }
+  DIDerivedType *getStaticDataMemberDeclaration() const {
+    return cast_or_null<DIDerivedType>(getRawStaticDataMemberDeclaration());
+  }
+
+  MDString *getRawLinkageName() const { return getOperandAs<MDString>(5); }
+  Metadata *getRawStaticDataMemberDeclaration() const { return getOperand(6); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIGlobalVariableKind;
+  }
+};
+
+/// Local variable.
+///
+/// TODO: Split up flags.
+class DILocalVariable : public DIVariable {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Arg : 16;
+  DIFlags Flags;
+
+  DILocalVariable(LLVMContext &C, StorageType Storage, unsigned Line,
+                  unsigned Arg, DIFlags Flags, uint32_t AlignInBits,
+                  ArrayRef<Metadata *> Ops)
+      : DIVariable(C, DILocalVariableKind, Storage, Line, Ops, AlignInBits),
+        Arg(Arg), Flags(Flags) {
+    assert(Arg < (1 << 16) && "DILocalVariable: Arg out of range");
+  }
+  ~DILocalVariable() = default;
+
+  static DILocalVariable *getImpl(LLVMContext &Context, DIScope *Scope,
+                                  StringRef Name, DIFile *File, unsigned Line,
+                                  DITypeRef Type, unsigned Arg, DIFlags Flags,
+                                  uint32_t AlignInBits, StorageType Storage,
+                                  bool ShouldCreate = true) {
+    return getImpl(Context, Scope, getCanonicalMDString(Context, Name), File,
+                   Line, Type, Arg, Flags, AlignInBits, Storage, ShouldCreate);
+  }
+  static DILocalVariable *getImpl(LLVMContext &Context, Metadata *Scope,
+                                  MDString *Name, Metadata *File, unsigned Line,
+                                  Metadata *Type, unsigned Arg, DIFlags Flags,
+                                  uint32_t AlignInBits, StorageType Storage,
+                                  bool ShouldCreate = true);
+
+  TempDILocalVariable cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getName(), getFile(),
+                        getLine(), getType(), getArg(), getFlags(),
+                        getAlignInBits());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DILocalVariable,
+                    (DILocalScope * Scope, StringRef Name, DIFile *File,
+                     unsigned Line, DITypeRef Type, unsigned Arg,
+                     DIFlags Flags, uint32_t AlignInBits),
+                    (Scope, Name, File, Line, Type, Arg, Flags, AlignInBits))
+  DEFINE_MDNODE_GET(DILocalVariable,
+                    (Metadata * Scope, MDString *Name, Metadata *File,
+                     unsigned Line, Metadata *Type, unsigned Arg,
+                     DIFlags Flags, uint32_t AlignInBits),
+                    (Scope, Name, File, Line, Type, Arg, Flags, AlignInBits))
+
+  TempDILocalVariable clone() const { return cloneImpl(); }
+
+  /// Get the local scope for this variable.
+  ///
+  /// Variables must be defined in a local scope.
+  DILocalScope *getScope() const {
+    return cast<DILocalScope>(DIVariable::getScope());
+  }
+
+  bool isParameter() const { return Arg; }
+  unsigned getArg() const { return Arg; }
+  DIFlags getFlags() const { return Flags; }
+
+  bool isArtificial() const { return getFlags() & FlagArtificial; }
+  bool isObjectPointer() const { return getFlags() & FlagObjectPointer; }
+
+  /// Check that a location is valid for this variable.
+  ///
+  /// Check that \c DL exists, is in the same subprogram, and has the same
+  /// inlined-at location as \c this.  (Otherwise, it's not a valid attachment
+  /// to a \a DbgInfoIntrinsic.)
+  bool isValidLocationForIntrinsic(const DILocation *DL) const {
+    return DL && getScope()->getSubprogram() == DL->getScope()->getSubprogram();
+  }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DILocalVariableKind;
+  }
+};
+
+class DIObjCProperty : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+  unsigned Attributes;
+
+  DIObjCProperty(LLVMContext &C, StorageType Storage, unsigned Line,
+                 unsigned Attributes, ArrayRef<Metadata *> Ops)
+      : DINode(C, DIObjCPropertyKind, Storage, dwarf::DW_TAG_APPLE_property,
+               Ops),
+        Line(Line), Attributes(Attributes) {}
+  ~DIObjCProperty() = default;
+
+  static DIObjCProperty *
+  getImpl(LLVMContext &Context, StringRef Name, DIFile *File, unsigned Line,
+          StringRef GetterName, StringRef SetterName, unsigned Attributes,
+          DITypeRef 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 DIObjCProperty *getImpl(LLVMContext &Context, MDString *Name,
+                                 Metadata *File, unsigned Line,
+                                 MDString *GetterName, MDString *SetterName,
+                                 unsigned Attributes, Metadata *Type,
+                                 StorageType Storage, bool ShouldCreate = true);
+
+  TempDIObjCProperty cloneImpl() const {
+    return getTemporary(getContext(), getName(), getFile(), getLine(),
+                        getGetterName(), getSetterName(), getAttributes(),
+                        getType());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIObjCProperty,
+                    (StringRef Name, DIFile *File, unsigned Line,
+                     StringRef GetterName, StringRef SetterName,
+                     unsigned Attributes, DITypeRef Type),
+                    (Name, File, Line, GetterName, SetterName, Attributes,
+                     Type))
+  DEFINE_MDNODE_GET(DIObjCProperty,
+                    (MDString * Name, Metadata *File, unsigned Line,
+                     MDString *GetterName, MDString *SetterName,
+                     unsigned Attributes, Metadata *Type),
+                    (Name, File, Line, GetterName, SetterName, Attributes,
+                     Type))
+
+  TempDIObjCProperty clone() const { return cloneImpl(); }
+
+  unsigned getLine() const { return Line; }
+  unsigned getAttributes() const { return Attributes; }
+  StringRef getName() const { return getStringOperand(0); }
+  DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
+  StringRef getGetterName() const { return getStringOperand(2); }
+  StringRef getSetterName() const { return getStringOperand(3); }
+  DITypeRef getType() const { return DITypeRef(getRawType()); }
+
+  StringRef getFilename() const {
+    if (auto *F = getFile())
+      return F->getFilename();
+    return "";
+  }
+
+  StringRef getDirectory() const {
+    if (auto *F = getFile())
+      return F->getDirectory();
+    return "";
+  }
+
+  Optional<StringRef> getSource() const {
+    if (auto *F = getFile())
+      return F->getSource();
+    return None;
+  }
+
+  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() == DIObjCPropertyKind;
+  }
+};
+
+/// An imported module (C++ using directive or similar).
+class DIImportedEntity : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+
+  DIImportedEntity(LLVMContext &C, StorageType Storage, unsigned Tag,
+                   unsigned Line, ArrayRef<Metadata *> Ops)
+      : DINode(C, DIImportedEntityKind, Storage, Tag, Ops), Line(Line) {}
+  ~DIImportedEntity() = default;
+
+  static DIImportedEntity *getImpl(LLVMContext &Context, unsigned Tag,
+                                   DIScope *Scope, DINodeRef Entity,
+                                   DIFile *File, unsigned Line, StringRef Name,
+                                   StorageType Storage,
+                                   bool ShouldCreate = true) {
+    return getImpl(Context, Tag, Scope, Entity, File, Line,
+                   getCanonicalMDString(Context, Name), Storage, ShouldCreate);
+  }
+  static DIImportedEntity *getImpl(LLVMContext &Context, unsigned Tag,
+                                   Metadata *Scope, Metadata *Entity,
+                                   Metadata *File, unsigned Line,
+                                   MDString *Name, StorageType Storage,
+                                   bool ShouldCreate = true);
+
+  TempDIImportedEntity cloneImpl() const {
+    return getTemporary(getContext(), getTag(), getScope(), getEntity(),
+                        getFile(), getLine(), getName());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIImportedEntity,
+                    (unsigned Tag, DIScope *Scope, DINodeRef Entity,
+                     DIFile *File, unsigned Line, StringRef Name = ""),
+                    (Tag, Scope, Entity, File, Line, Name))
+  DEFINE_MDNODE_GET(DIImportedEntity,
+                    (unsigned Tag, Metadata *Scope, Metadata *Entity,
+                     Metadata *File, unsigned Line, MDString *Name),
+                    (Tag, Scope, Entity, File, Line, Name))
+
+  TempDIImportedEntity clone() const { return cloneImpl(); }
+
+  unsigned getLine() const { return Line; }
+  DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
+  DINodeRef getEntity() const { return DINodeRef(getRawEntity()); }
+  StringRef getName() const { return getStringOperand(2); }
+  DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
+
+  Metadata *getRawScope() const { return getOperand(0); }
+  Metadata *getRawEntity() const { return getOperand(1); }
+  MDString *getRawName() const { return getOperandAs<MDString>(2); }
+  Metadata *getRawFile() const { return getOperand(3); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIImportedEntityKind;
+  }
+};
+
+/// A pair of DIGlobalVariable and DIExpression.
+class DIGlobalVariableExpression : public MDNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  DIGlobalVariableExpression(LLVMContext &C, StorageType Storage,
+                             ArrayRef<Metadata *> Ops)
+      : MDNode(C, DIGlobalVariableExpressionKind, Storage, Ops) {}
+  ~DIGlobalVariableExpression() = default;
+
+  static DIGlobalVariableExpression *
+  getImpl(LLVMContext &Context, Metadata *Variable, Metadata *Expression,
+          StorageType Storage, bool ShouldCreate = true);
+
+  TempDIGlobalVariableExpression cloneImpl() const {
+    return getTemporary(getContext(), getVariable(), getExpression());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIGlobalVariableExpression,
+                    (Metadata * Variable, Metadata *Expression),
+                    (Variable, Expression))
+
+  TempDIGlobalVariableExpression clone() const { return cloneImpl(); }
+
+  Metadata *getRawVariable() const { return getOperand(0); }
+
+  DIGlobalVariable *getVariable() const {
+    return cast_or_null<DIGlobalVariable>(getRawVariable());
+  }
+
+  Metadata *getRawExpression() const { return getOperand(1); }
+
+  DIExpression *getExpression() const {
+    return cast<DIExpression>(getRawExpression());
+  }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIGlobalVariableExpressionKind;
+  }
+};
+
+/// Macro Info DWARF-like metadata node.
+///
+/// A metadata node with a DWARF macro info (i.e., a constant named
+/// \c DW_MACINFO_*, defined in llvm/BinaryFormat/Dwarf.h).  Called \a
+/// DIMacroNode
+/// because it's potentially used for non-DWARF output.
+class DIMacroNode : public MDNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+protected:
+  DIMacroNode(LLVMContext &C, unsigned ID, StorageType Storage, unsigned MIType,
+              ArrayRef<Metadata *> Ops1, ArrayRef<Metadata *> Ops2 = None)
+      : MDNode(C, ID, Storage, Ops1, Ops2) {
+    assert(MIType < 1u << 16);
+    SubclassData16 = MIType;
+  }
+  ~DIMacroNode() = default;
+
+  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 getMacinfoType() const { return SubclassData16; }
+
+  static bool classof(const Metadata *MD) {
+    switch (MD->getMetadataID()) {
+    default:
+      return false;
+    case DIMacroKind:
+    case DIMacroFileKind:
+      return true;
+    }
+  }
+};
+
+class DIMacro : public DIMacroNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+
+  DIMacro(LLVMContext &C, StorageType Storage, unsigned MIType, unsigned Line,
+          ArrayRef<Metadata *> Ops)
+      : DIMacroNode(C, DIMacroKind, Storage, MIType, Ops), Line(Line) {}
+  ~DIMacro() = default;
+
+  static DIMacro *getImpl(LLVMContext &Context, unsigned MIType, unsigned Line,
+                          StringRef Name, StringRef Value, StorageType Storage,
+                          bool ShouldCreate = true) {
+    return getImpl(Context, MIType, Line, getCanonicalMDString(Context, Name),
+                   getCanonicalMDString(Context, Value), Storage, ShouldCreate);
+  }
+  static DIMacro *getImpl(LLVMContext &Context, unsigned MIType, unsigned Line,
+                          MDString *Name, MDString *Value, StorageType Storage,
+                          bool ShouldCreate = true);
+
+  TempDIMacro cloneImpl() const {
+    return getTemporary(getContext(), getMacinfoType(), getLine(), getName(),
+                        getValue());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIMacro, (unsigned MIType, unsigned Line, StringRef Name,
+                              StringRef Value = ""),
+                    (MIType, Line, Name, Value))
+  DEFINE_MDNODE_GET(DIMacro, (unsigned MIType, unsigned Line, MDString *Name,
+                              MDString *Value),
+                    (MIType, Line, Name, Value))
+
+  TempDIMacro clone() const { return cloneImpl(); }
+
+  unsigned getLine() const { return Line; }
+
+  StringRef getName() const { return getStringOperand(0); }
+  StringRef getValue() const { return getStringOperand(1); }
+
+  MDString *getRawName() const { return getOperandAs<MDString>(0); }
+  MDString *getRawValue() const { return getOperandAs<MDString>(1); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIMacroKind;
+  }
+};
+
+class DIMacroFile : public DIMacroNode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+
+  DIMacroFile(LLVMContext &C, StorageType Storage, unsigned MIType,
+              unsigned Line, ArrayRef<Metadata *> Ops)
+      : DIMacroNode(C, DIMacroFileKind, Storage, MIType, Ops), Line(Line) {}
+  ~DIMacroFile() = default;
+
+  static DIMacroFile *getImpl(LLVMContext &Context, unsigned MIType,
+                              unsigned Line, DIFile *File,
+                              DIMacroNodeArray Elements, StorageType Storage,
+                              bool ShouldCreate = true) {
+    return getImpl(Context, MIType, Line, static_cast<Metadata *>(File),
+                   Elements.get(), Storage, ShouldCreate);
+  }
+
+  static DIMacroFile *getImpl(LLVMContext &Context, unsigned MIType,
+                              unsigned Line, Metadata *File, Metadata *Elements,
+                              StorageType Storage, bool ShouldCreate = true);
+
+  TempDIMacroFile cloneImpl() const {
+    return getTemporary(getContext(), getMacinfoType(), getLine(), getFile(),
+                        getElements());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIMacroFile, (unsigned MIType, unsigned Line, DIFile *File,
+                                  DIMacroNodeArray Elements),
+                    (MIType, Line, File, Elements))
+  DEFINE_MDNODE_GET(DIMacroFile, (unsigned MIType, unsigned Line,
+                                  Metadata *File, Metadata *Elements),
+                    (MIType, Line, File, Elements))
+
+  TempDIMacroFile clone() const { return cloneImpl(); }
+
+  void replaceElements(DIMacroNodeArray Elements) {
+#ifndef NDEBUG
+    for (DIMacroNode *Op : getElements())
+      assert(is_contained(Elements->operands(), Op) &&
+             "Lost a macro node during macro node list replacement");
+#endif
+    replaceOperandWith(1, Elements.get());
+  }
+
+  unsigned getLine() const { return Line; }
+  DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
+
+  DIMacroNodeArray getElements() const {
+    return cast_or_null<MDTuple>(getRawElements());
+  }
+
+  Metadata *getRawFile() const { return getOperand(0); }
+  Metadata *getRawElements() const { return getOperand(1); }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIMacroFileKind;
+  }
+};
+
+} // end namespace llvm
+
+#undef DEFINE_MDNODE_GET_UNPACK_IMPL
+#undef DEFINE_MDNODE_GET_UNPACK
+#undef DEFINE_MDNODE_GET
+
+#endif // LLVM_IR_DEBUGINFOMETADATA_H