DebugInfo: Remove DIArray and DITypeArray typedefs
[oota-llvm.git] / lib / IR / DIBuilder.cpp
index 2903b9d34531f9c02f54459e75bb281f70f88a63..c849f1030bc2d99f52dd8dd844aa83e4139185b9 100644 (file)
 using namespace llvm;
 using namespace llvm::dwarf;
 
-static Constant *GetTagConstant(LLVMContext &VMContext, unsigned Tag) {
-  assert((Tag & LLVMDebugVersionMask) == 0 &&
-         "Tag too large for debug encoding!");
-  return ConstantInt::get(Type::getInt32Ty(VMContext), Tag | LLVMDebugVersion);
+namespace {
+class HeaderBuilder {
+  /// \brief Whether there are any fields yet.
+  ///
+  /// Note that this is not equivalent to \c Chars.empty(), since \a concat()
+  /// may have been called already with an empty string.
+  bool IsEmpty;
+  SmallVector<char, 256> Chars;
+
+public:
+  HeaderBuilder() : IsEmpty(true) {}
+  HeaderBuilder(const HeaderBuilder &X) : IsEmpty(X.IsEmpty), Chars(X.Chars) {}
+  HeaderBuilder(HeaderBuilder &&X)
+      : IsEmpty(X.IsEmpty), Chars(std::move(X.Chars)) {}
+
+  template <class Twineable> HeaderBuilder &concat(Twineable &&X) {
+    if (IsEmpty)
+      IsEmpty = false;
+    else
+      Chars.push_back(0);
+    Twine(X).toVector(Chars);
+    return *this;
+  }
+
+  MDString *get(LLVMContext &Context) const {
+    return MDString::get(Context, StringRef(Chars.begin(), Chars.size()));
+  }
+
+  static HeaderBuilder get(unsigned Tag) {
+    return HeaderBuilder().concat("0x" + Twine::utohexstr(Tag));
+  }
+};
 }
 
-DIBuilder::DIBuilder(Module &m)
+DIBuilder::DIBuilder(Module &m, bool AllowUnresolvedNodes)
     : M(m), VMContext(M.getContext()), TempEnumTypes(nullptr),
       TempRetainTypes(nullptr), TempSubprograms(nullptr), TempGVs(nullptr),
-      DeclareFn(nullptr), ValueFn(nullptr) {}
+      DeclareFn(nullptr), ValueFn(nullptr),
+      AllowUnresolvedNodes(AllowUnresolvedNodes) {}
+
+void DIBuilder::trackIfUnresolved(MDNode *N) {
+  if (!N)
+    return;
+  if (N->isResolved())
+    return;
+
+  assert(AllowUnresolvedNodes && "Cannot handle unresolved nodes");
+  UnresolvedNodes.emplace_back(N);
+}
 
-/// finalize - Construct any deferred debug info descriptors.
 void DIBuilder::finalize() {
-  DIArray Enums = getOrCreateArray(AllEnumTypes);
-  DIType(TempEnumTypes).replaceAllUsesWith(Enums);
+  TempEnumTypes->replaceAllUsesWith(MDTuple::get(VMContext, AllEnumTypes));
 
-  SmallVector<Value *, 16> RetainValues;
+  SmallVector<Metadata *, 16> RetainValues;
   // Declarations and definitions of the same type may be retained. Some
   // clients RAUW these pairs, leaving duplicates in the retained types
   // list. Use a set to remove the duplicates while we transform the
   // TrackingVHs back into Values.
-  SmallPtrSet<Value *, 16> RetainSet;
+  SmallPtrSet<Metadata *, 16> RetainSet;
   for (unsigned I = 0, E = AllRetainTypes.size(); I < E; I++)
-    if (RetainSet.insert(AllRetainTypes[I]))
+    if (RetainSet.insert(AllRetainTypes[I]).second)
       RetainValues.push_back(AllRetainTypes[I]);
-  DIArray RetainTypes = getOrCreateArray(RetainValues);
-  DIType(TempRetainTypes).replaceAllUsesWith(RetainTypes);
-
-  DIArray SPs = getOrCreateArray(AllSubprograms);
-  DIType(TempSubprograms).replaceAllUsesWith(SPs);
-  for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
-    DISubprogram SP(SPs.getElement(i));
-    SmallVector<Value *, 4> Variables;
-    if (NamedMDNode *NMD = getFnSpecificMDNode(M, SP)) {
-      for (unsigned ii = 0, ee = NMD->getNumOperands(); ii != ee; ++ii)
-        Variables.push_back(NMD->getOperand(ii));
-      NMD->eraseFromParent();
-    }
-    if (MDNode *Temp = SP.getVariablesNodes()) {
-      DIArray AV = getOrCreateArray(Variables);
-      DIType(Temp).replaceAllUsesWith(AV);
+  TempRetainTypes->replaceAllUsesWith(MDTuple::get(VMContext, RetainValues));
+
+  MDSubprogramArray SPs = MDTuple::get(VMContext, AllSubprograms);
+  TempSubprograms->replaceAllUsesWith(SPs.get());
+  for (auto *SP : SPs) {
+    if (MDTuple *Temp = SP->getVariables().get()) {
+      const auto &PV = PreservedVariables.lookup(SP);
+      SmallVector<Metadata *, 4> Variables(PV.begin(), PV.end());
+      DebugNodeArray AV = getOrCreateArray(Variables);
+      TempMDTuple(Temp)->replaceAllUsesWith(AV.get());
     }
   }
 
-  DIArray GVs = getOrCreateArray(AllGVs);
-  DIType(TempGVs).replaceAllUsesWith(GVs);
+  TempGVs->replaceAllUsesWith(MDTuple::get(VMContext, AllGVs));
 
-  SmallVector<Value *, 16> RetainValuesI;
-  for (unsigned I = 0, E = AllImportedModules.size(); I < E; I++)
-    RetainValuesI.push_back(AllImportedModules[I]);
-  DIArray IMs = getOrCreateArray(RetainValuesI);
-  DIType(TempImportedModules).replaceAllUsesWith(IMs);
-}
+  TempImportedModules->replaceAllUsesWith(MDTuple::get(
+      VMContext, SmallVector<Metadata *, 16>(AllImportedModules.begin(),
+                                             AllImportedModules.end())));
 
-/// getNonCompileUnitScope - If N is compile unit return NULL otherwise return
-/// N.
-static MDNode *getNonCompileUnitScope(MDNode *N) {
-  if (DIDescriptor(N).isCompileUnit())
-    return nullptr;
-  return N;
+  // Now that all temp nodes have been replaced or deleted, resolve remaining
+  // cycles.
+  for (const auto &N : UnresolvedNodes)
+    if (N && !N->isResolved())
+      N->resolveCycles();
+  UnresolvedNodes.clear();
+
+  // Can't handle unresolved nodes anymore.
+  AllowUnresolvedNodes = false;
 }
 
-static MDNode *createFilePathPair(LLVMContext &VMContext, StringRef Filename,
-                                  StringRef Directory) {
-  assert(!Filename.empty() && "Unable to create file without name");
-  Value *Pair[] = {
-    MDString::get(VMContext, Filename),
-    MDString::get(VMContext, Directory)
-  };
-  return MDNode::get(VMContext, Pair);
+/// If N is compile unit return NULL otherwise return N.
+static MDScope *getNonCompileUnitScope(MDScope *N) {
+  if (!N || isa<MDCompileUnit>(N))
+    return nullptr;
+  return cast<MDScope>(N);
 }
 
-/// createCompileUnit - A CompileUnit provides an anchor for all debugging
-/// information generated during this instance of compilation.
-DICompileUnit DIBuilder::createCompileUnit(unsigned Lang, StringRef Filename,
-                                           StringRef Directory,
-                                           StringRef Producer, bool isOptimized,
-                                           StringRef Flags, unsigned RunTimeVer,
-                                           StringRef SplitName,
-                                           DebugEmissionKind Kind,
-                                           bool EmitDebugInfo) {
+MDCompileUnit *DIBuilder::createCompileUnit(
+    unsigned Lang, StringRef Filename, StringRef Directory, StringRef Producer,
+    bool isOptimized, StringRef Flags, unsigned RunTimeVer, StringRef SplitName,
+    DebugEmissionKind Kind, bool EmitDebugInfo) {
 
-  assert(((Lang <= dwarf::DW_LANG_OCaml && Lang >= dwarf::DW_LANG_C89) ||
+  assert(((Lang <= dwarf::DW_LANG_Fortran08 && Lang >= dwarf::DW_LANG_C89) ||
           (Lang <= dwarf::DW_LANG_hi_user && Lang >= dwarf::DW_LANG_lo_user)) &&
          "Invalid Language tag");
   assert(!Filename.empty() &&
          "Unable to create compile unit without filename");
-  Value *TElts[] = { GetTagConstant(VMContext, DW_TAG_base_type) };
-  TempEnumTypes = MDNode::getTemporary(VMContext, TElts);
-
-  TempRetainTypes = MDNode::getTemporary(VMContext, TElts);
-
-  TempSubprograms = MDNode::getTemporary(VMContext, TElts);
 
-  TempGVs = MDNode::getTemporary(VMContext, TElts);
-
-  TempImportedModules = MDNode::getTemporary(VMContext, TElts);
-
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_compile_unit),
-    createFilePathPair(VMContext, Filename, Directory),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Lang),
-    MDString::get(VMContext, Producer),
-    ConstantInt::get(Type::getInt1Ty(VMContext), isOptimized),
-    MDString::get(VMContext, Flags),
-    ConstantInt::get(Type::getInt32Ty(VMContext), RunTimeVer),
-    TempEnumTypes,
-    TempRetainTypes,
-    TempSubprograms,
-    TempGVs,
-    TempImportedModules,
-    MDString::get(VMContext, SplitName),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Kind)
-  };
-
-  MDNode *CUNode = MDNode::get(VMContext, Elts);
+  // TODO: Once we make MDCompileUnit distinct, stop using temporaries here
+  // (just start with operands assigned to nullptr).
+  TempEnumTypes = MDTuple::getTemporary(VMContext, None);
+  TempRetainTypes = MDTuple::getTemporary(VMContext, None);
+  TempSubprograms = MDTuple::getTemporary(VMContext, None);
+  TempGVs = MDTuple::getTemporary(VMContext, None);
+  TempImportedModules = MDTuple::getTemporary(VMContext, None);
+
+  // TODO: Switch to getDistinct().  We never want to merge compile units based
+  // on contents.
+  MDCompileUnit *CUNode = MDCompileUnit::get(
+      VMContext, Lang, MDFile::get(VMContext, Filename, Directory), Producer,
+      isOptimized, Flags, RunTimeVer, SplitName, Kind, TempEnumTypes.get(),
+      TempRetainTypes.get(), TempSubprograms.get(), TempGVs.get(),
+      TempImportedModules.get());
 
   // Create a named metadata so that it is easier to find cu in a module.
   // Note that we only generate this when the caller wants to actually
@@ -150,966 +159,474 @@ DICompileUnit DIBuilder::createCompileUnit(unsigned Lang, StringRef Filename,
     NMD->addOperand(CUNode);
   }
 
-  return DICompileUnit(CUNode);
-}
-
-static DIImportedEntity
-createImportedModule(LLVMContext &C, dwarf::Tag Tag, DIScope Context,
-                     Value *NS, unsigned Line, StringRef Name,
-                     SmallVectorImpl<TrackingVH<MDNode>> &AllImportedModules) {
-  const MDNode *R;
-  if (Name.empty()) {
-    Value *Elts[] = {
-      GetTagConstant(C, Tag),
-      Context,
-      NS,
-      ConstantInt::get(Type::getInt32Ty(C), Line),
-    };
-    R = MDNode::get(C, Elts);
-  } else {
-    Value *Elts[] = {
-      GetTagConstant(C, Tag),
-      Context,
-      NS,
-      ConstantInt::get(Type::getInt32Ty(C), Line),
-      MDString::get(C, Name)
-    };
-    R = MDNode::get(C, Elts);
-  }
-  DIImportedEntity M(R);
-  assert(M.Verify() && "Imported module should be valid");
-  AllImportedModules.push_back(TrackingVH<MDNode>(M));
+  trackIfUnresolved(CUNode);
+  return CUNode;
+}
+
+static MDImportedEntity*
+createImportedModule(LLVMContext &C, dwarf::Tag Tag, MDScope* Context,
+                     Metadata *NS, unsigned Line, StringRef Name,
+                     SmallVectorImpl<TrackingMDNodeRef> &AllImportedModules) {
+  auto *M =
+      MDImportedEntity::get(C, Tag, Context, DebugNodeRef(NS), Line, Name);
+  AllImportedModules.emplace_back(M);
   return M;
 }
 
-DIImportedEntity DIBuilder::createImportedModule(DIScope Context,
-                                                 DINameSpace NS,
+MDImportedEntity* DIBuilder::createImportedModule(MDScope* Context,
+                                                 MDNamespace* NS,
                                                  unsigned Line) {
   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
                                 Context, NS, Line, StringRef(), AllImportedModules);
 }
 
-DIImportedEntity DIBuilder::createImportedModule(DIScope Context,
-                                                 DIImportedEntity NS,
+MDImportedEntity* DIBuilder::createImportedModule(MDScope* Context,
+                                                 MDImportedEntity* NS,
                                                  unsigned Line) {
   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
                                 Context, NS, Line, StringRef(), AllImportedModules);
 }
 
-DIImportedEntity DIBuilder::createImportedDeclaration(DIScope Context,
-                                                      DIScope Decl,
-                                                      unsigned Line, StringRef Name) {
+MDImportedEntity *DIBuilder::createImportedDeclaration(MDScope *Context,
+                                                       DebugNode *Decl,
+                                                       unsigned Line,
+                                                       StringRef Name) {
+  // Make sure to use the unique identifier based metadata reference for
+  // types that have one.
   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_declaration,
-                                Context, Decl.getRef(), Line, Name,
+                                Context, DebugNodeRef::get(Decl), Line, Name,
                                 AllImportedModules);
 }
 
-DIImportedEntity DIBuilder::createImportedDeclaration(DIScope Context,
-                                                      DIImportedEntity Imp,
-                                                      unsigned Line, StringRef Name) {
-  return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_declaration,
-                                Context, Imp, Line, Name, AllImportedModules);
-}
-
-/// createFile - Create a file descriptor to hold debugging information
-/// for a file.
-DIFile DIBuilder::createFile(StringRef Filename, StringRef Directory) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_file_type),
-    createFilePathPair(VMContext, Filename, Directory)
-  };
-  return DIFile(MDNode::get(VMContext, Elts));
+MDFile* DIBuilder::createFile(StringRef Filename, StringRef Directory) {
+  return MDFile::get(VMContext, Filename, Directory);
 }
 
-/// createEnumerator - Create a single enumerator value.
-DIEnumerator DIBuilder::createEnumerator(StringRef Name, int64_t Val) {
+MDEnumerator *DIBuilder::createEnumerator(StringRef Name, int64_t Val) {
   assert(!Name.empty() && "Unable to create enumerator without name");
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_enumerator),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt64Ty(VMContext), Val)
-  };
-  return DIEnumerator(MDNode::get(VMContext, Elts));
+  return MDEnumerator::get(VMContext, Val, Name);
 }
 
-/// \brief Create a DWARF unspecified type.
-DIBasicType DIBuilder::createUnspecifiedType(StringRef Name) {
+MDBasicType *DIBuilder::createUnspecifiedType(StringRef Name) {
   assert(!Name.empty() && "Unable to create type without name");
-  // Unspecified types are encoded in DIBasicType format. Line number, filename,
-  // size, alignment, offset and flags are always empty here.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_unspecified_type),
-    nullptr, // Filename
-    nullptr, // Unused
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags;
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0)  // Encoding
-  };
-  return DIBasicType(MDNode::get(VMContext, Elts));
-}
-
-/// \brief Create C++11 nullptr type.
-DIBasicType DIBuilder::createNullPtrType() {
+  return MDBasicType::get(VMContext, dwarf::DW_TAG_unspecified_type, Name);
+}
+
+MDBasicType *DIBuilder::createNullPtrType() {
   return createUnspecifiedType("decltype(nullptr)");
 }
 
-/// createBasicType - Create debugging information entry for a basic
-/// type, e.g 'char'.
-DIBasicType
-DIBuilder::createBasicType(StringRef Name, uint64_t SizeInBits,
-                           uint64_t AlignInBits, unsigned Encoding) {
-  assert(!Name.empty() && "Unable to create type without name");
-  // Basic types are encoded in DIBasicType format. Line number, filename,
-  // offset and flags are always empty here.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_base_type),
-    nullptr, // File/directory name
-    nullptr, // Unused
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags;
-    ConstantInt::get(Type::getInt32Ty(VMContext), Encoding)
-  };
-  return DIBasicType(MDNode::get(VMContext, Elts));
-}
-
-/// createQualifiedType - Create debugging information entry for a qualified
-/// type, e.g. 'const int'.
-DIDerivedType DIBuilder::createQualifiedType(unsigned Tag, DIType FromTy) {
-  // Qualified types are encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    nullptr, // Filename
-    nullptr, // Unused
-    MDString::get(VMContext, StringRef()), // Empty name.
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    FromTy.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createPointerType - Create debugging information entry for a pointer.
-DIDerivedType
-DIBuilder::createPointerType(DIType PointeeTy, uint64_t SizeInBits,
-                             uint64_t AlignInBits, StringRef Name) {
-  // Pointer types are encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_pointer_type),
-    nullptr, // Filename
-    nullptr, // Unused
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    PointeeTy.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-DIDerivedType DIBuilder::createMemberPointerType(DIType PointeeTy,
-                                                 DIType Base) {
-  // Pointer types are encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_ptr_to_member_type),
-    nullptr, // Filename
-    nullptr, // Unused
-    nullptr,
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    PointeeTy.getRef(),
-    Base.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createReferenceType - Create debugging information entry for a reference
-/// type.
-DIDerivedType DIBuilder::createReferenceType(unsigned Tag, DIType RTy) {
-  assert(RTy.isType() && "Unable to create reference type");
-  // References are encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    nullptr, // Filename
-    nullptr, // TheCU,
-    nullptr, // Name
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    RTy.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createTypedef - Create debugging information entry for a typedef.
-DIDerivedType DIBuilder::createTypedef(DIType Ty, StringRef Name, DIFile File,
-                                       unsigned LineNo, DIDescriptor Context) {
-  // typedefs are encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_typedef),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Context)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    Ty.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createFriend - Create debugging information entry for a 'friend'.
-DIDerivedType DIBuilder::createFriend(DIType Ty, DIType FriendTy) {
-  // typedefs are encoded in DIDerivedType format.
-  assert(Ty.isType() && "Invalid type!");
-  assert(FriendTy.isType() && "Invalid friend type!");
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_friend),
-    nullptr,
-    Ty.getRef(),
-    nullptr, // Name
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    FriendTy.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createInheritance - Create debugging information entry to establish
-/// inheritance relationship between two types.
-DIDerivedType DIBuilder::createInheritance(DIType Ty, DIType BaseTy,
-                                           uint64_t BaseOffset,
-                                           unsigned Flags) {
-  assert(Ty.isType() && "Unable to create inheritance");
-  // TAG_inheritance is encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_inheritance),
-    nullptr,
-    Ty.getRef(),
-    nullptr, // Name
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), BaseOffset),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    BaseTy.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createMemberType - Create debugging information entry for a member.
-DIDerivedType DIBuilder::createMemberType(DIDescriptor Scope, StringRef Name,
-                                          DIFile File, unsigned LineNumber,
-                                          uint64_t SizeInBits,
-                                          uint64_t AlignInBits,
-                                          uint64_t OffsetInBits, unsigned Flags,
-                                          DIType Ty) {
-  // TAG_member is encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_member),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Scope)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), OffsetInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    Ty.getRef()
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createStaticMemberType - Create debugging information entry for a
-/// C++ static data member.
-DIDerivedType
-DIBuilder::createStaticMemberType(DIDescriptor Scope, StringRef Name,
-                                  DIFile File, unsigned LineNumber,
-                                  DIType Ty, unsigned Flags,
-                                  llvm::Value *Val) {
-  // TAG_member is encoded in DIDerivedType format.
-  Flags |= DIDescriptor::FlagStaticMember;
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_member),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Scope)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    Ty.getRef(),
-    Val
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createObjCIVar - Create debugging information entry for Objective-C
-/// instance variable.
-DIDerivedType
-DIBuilder::createObjCIVar(StringRef Name, DIFile File, unsigned LineNumber,
-                          uint64_t SizeInBits, uint64_t AlignInBits,
-                          uint64_t OffsetInBits, unsigned Flags, DIType Ty,
-                          StringRef PropertyName, StringRef GetterName,
-                          StringRef SetterName, unsigned PropertyAttributes) {
-  // TAG_member is encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_member),
-    File.getFileNode(),
-    getNonCompileUnitScope(File),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), OffsetInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    Ty,
-    MDString::get(VMContext, PropertyName),
-    MDString::get(VMContext, GetterName),
-    MDString::get(VMContext, SetterName),
-    ConstantInt::get(Type::getInt32Ty(VMContext), PropertyAttributes)
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createObjCIVar - Create debugging information entry for Objective-C
-/// instance variable.
-DIDerivedType DIBuilder::createObjCIVar(StringRef Name, DIFile File,
-                                        unsigned LineNumber,
-                                        uint64_t SizeInBits,
+MDBasicType *DIBuilder::createBasicType(StringRef Name, uint64_t SizeInBits,
                                         uint64_t AlignInBits,
-                                        uint64_t OffsetInBits, unsigned Flags,
-                                        DIType Ty, MDNode *PropertyNode) {
-  // TAG_member is encoded in DIDerivedType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_member),
-    File.getFileNode(),
-    getNonCompileUnitScope(File),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), OffsetInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    Ty,
-    PropertyNode
-  };
-  return DIDerivedType(MDNode::get(VMContext, Elts));
-}
-
-/// createObjCProperty - Create debugging information entry for Objective-C
-/// property.
-DIObjCProperty
-DIBuilder::createObjCProperty(StringRef Name, DIFile File, unsigned LineNumber,
-                              StringRef GetterName, StringRef SetterName,
-                              unsigned PropertyAttributes, DIType Ty) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_APPLE_property),
-    MDString::get(VMContext, Name),
-    File,
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    MDString::get(VMContext, GetterName),
-    MDString::get(VMContext, SetterName),
-    ConstantInt::get(Type::getInt32Ty(VMContext), PropertyAttributes),
-    Ty
-  };
-  return DIObjCProperty(MDNode::get(VMContext, Elts));
-}
-
-/// createTemplateTypeParameter - Create debugging information for template
-/// type parameter.
-DITemplateTypeParameter
-DIBuilder::createTemplateTypeParameter(DIDescriptor Context, StringRef Name,
-                                       DIType Ty, MDNode *File, unsigned LineNo,
-                                       unsigned ColumnNo) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_template_type_parameter),
-    DIScope(getNonCompileUnitScope(Context)).getRef(),
-    MDString::get(VMContext, Name),
-    Ty.getRef(),
-    File,
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
-    ConstantInt::get(Type::getInt32Ty(VMContext), ColumnNo)
-  };
-  return DITemplateTypeParameter(MDNode::get(VMContext, Elts));
-}
-
-DITemplateValueParameter
-DIBuilder::createTemplateValueParameter(unsigned Tag, DIDescriptor Context,
-                                        StringRef Name, DIType Ty,
-                                        Value *Val, MDNode *File,
-                                        unsigned LineNo,
-                                        unsigned ColumnNo) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    DIScope(getNonCompileUnitScope(Context)).getRef(),
-    MDString::get(VMContext, Name),
-    Ty.getRef(),
-    Val,
-    File,
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
-    ConstantInt::get(Type::getInt32Ty(VMContext), ColumnNo)
-  };
-  return DITemplateValueParameter(MDNode::get(VMContext, Elts));
-}
-
-/// createTemplateValueParameter - Create debugging information for template
-/// value parameter.
-DITemplateValueParameter
-DIBuilder::createTemplateValueParameter(DIDescriptor Context, StringRef Name,
-                                        DIType Ty, Value *Val,
-                                        MDNode *File, unsigned LineNo,
-                                        unsigned ColumnNo) {
-  return createTemplateValueParameter(dwarf::DW_TAG_template_value_parameter,
-                                      Context, Name, Ty, Val, File, LineNo,
-                                      ColumnNo);
-}
-
-DITemplateValueParameter
-DIBuilder::createTemplateTemplateParameter(DIDescriptor Context, StringRef Name,
-                                           DIType Ty, StringRef Val,
-                                           MDNode *File, unsigned LineNo,
-                                           unsigned ColumnNo) {
-  return createTemplateValueParameter(
-      dwarf::DW_TAG_GNU_template_template_param, Context, Name, Ty,
-      MDString::get(VMContext, Val), File, LineNo, ColumnNo);
-}
-
-DITemplateValueParameter
-DIBuilder::createTemplateParameterPack(DIDescriptor Context, StringRef Name,
-                                       DIType Ty, DIArray Val,
-                                       MDNode *File, unsigned LineNo,
-                                       unsigned ColumnNo) {
-  return createTemplateValueParameter(dwarf::DW_TAG_GNU_template_parameter_pack,
-                                      Context, Name, Ty, Val, File, LineNo,
-                                      ColumnNo);
-}
-
-/// createClassType - Create debugging information entry for a class.
-DICompositeType DIBuilder::createClassType(DIDescriptor Context, StringRef Name,
-                                           DIFile File, unsigned LineNumber,
+                                        unsigned Encoding) {
+  assert(!Name.empty() && "Unable to create type without name");
+  return MDBasicType::get(VMContext, dwarf::DW_TAG_base_type, Name, SizeInBits,
+                          AlignInBits, Encoding);
+}
+
+MDDerivedType *DIBuilder::createQualifiedType(unsigned Tag, MDType *FromTy) {
+  return MDDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr,
+                            MDTypeRef::get(FromTy), 0, 0, 0, 0);
+}
+
+MDDerivedType *DIBuilder::createPointerType(MDType *PointeeTy,
+                                            uint64_t SizeInBits,
+                                            uint64_t AlignInBits,
+                                            StringRef Name) {
+  // FIXME: Why is there a name here?
+  return MDDerivedType::get(VMContext, dwarf::DW_TAG_pointer_type, Name,
+                            nullptr, 0, nullptr, MDTypeRef::get(PointeeTy),
+                            SizeInBits, AlignInBits, 0, 0);
+}
+
+MDDerivedType *DIBuilder::createMemberPointerType(MDType *PointeeTy,
+                                                  MDType *Base,
+                                                  uint64_t SizeInBits,
+                                                  uint64_t AlignInBits) {
+  return MDDerivedType::get(VMContext, dwarf::DW_TAG_ptr_to_member_type, "",
+                            nullptr, 0, nullptr, MDTypeRef::get(PointeeTy),
+                            SizeInBits, AlignInBits, 0, 0, MDTypeRef::get(Base));
+}
+
+MDDerivedType *DIBuilder::createReferenceType(unsigned Tag, MDType *RTy) {
+  assert(RTy && "Unable to create reference type");
+  return MDDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr,
+                            MDTypeRef::get(RTy), 0, 0, 0, 0);
+}
+
+MDDerivedType *DIBuilder::createTypedef(MDType *Ty, StringRef Name,
+                                        MDFile *File, unsigned LineNo,
+                                        MDScope *Context) {
+  return MDDerivedType::get(VMContext, dwarf::DW_TAG_typedef, Name, File,
+                            LineNo,
+                            MDScopeRef::get(getNonCompileUnitScope(Context)),
+                            MDTypeRef::get(Ty), 0, 0, 0, 0);
+}
+
+MDDerivedType *DIBuilder::createFriend(MDType *Ty, MDType *FriendTy) {
+  assert(Ty && "Invalid type!");
+  assert(FriendTy && "Invalid friend type!");
+  return MDDerivedType::get(VMContext, dwarf::DW_TAG_friend, "", nullptr, 0,
+                            MDTypeRef::get(Ty), MDTypeRef::get(FriendTy), 0, 0,
+                            0, 0);
+}
+
+MDDerivedType *DIBuilder::createInheritance(MDType *Ty, MDType *BaseTy,
+                                            uint64_t BaseOffset,
+                                            unsigned Flags) {
+  assert(Ty && "Unable to create inheritance");
+  return MDDerivedType::get(VMContext, dwarf::DW_TAG_inheritance, "", nullptr,
+                            0, MDTypeRef::get(Ty), MDTypeRef::get(BaseTy), 0, 0,
+                            BaseOffset, Flags);
+}
+
+MDDerivedType *DIBuilder::createMemberType(MDScope *Scope, StringRef Name,
+                                           MDFile *File, unsigned LineNumber,
                                            uint64_t SizeInBits,
                                            uint64_t AlignInBits,
                                            uint64_t OffsetInBits,
-                                           unsigned Flags, DIType DerivedFrom,
-                                           DIArray Elements,
-                                           DIType VTableHolder,
-                                           MDNode *TemplateParams,
-                                           StringRef UniqueIdentifier) {
-  assert((!Context || Context.isScope() || Context.isType()) &&
+                                           unsigned Flags, MDType *Ty) {
+  return MDDerivedType::get(
+      VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(Scope)), MDTypeRef::get(Ty),
+      SizeInBits, AlignInBits, OffsetInBits, Flags);
+}
+
+static ConstantAsMetadata *getConstantOrNull(Constant *C) {
+  if (C)
+    return ConstantAsMetadata::get(C);
+  return nullptr;
+}
+
+MDDerivedType *DIBuilder::createStaticMemberType(MDScope *Scope, StringRef Name,
+                                                 MDFile *File,
+                                                 unsigned LineNumber,
+                                                 MDType *Ty, unsigned Flags,
+                                                 llvm::Constant *Val) {
+  Flags |= DebugNode::FlagStaticMember;
+  return MDDerivedType::get(
+      VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(Scope)), MDTypeRef::get(Ty), 0, 0,
+      0, Flags, getConstantOrNull(Val));
+}
+
+MDDerivedType *DIBuilder::createObjCIVar(StringRef Name, MDFile *File,
+                                         unsigned LineNumber,
+                                         uint64_t SizeInBits,
+                                         uint64_t AlignInBits,
+                                         uint64_t OffsetInBits, unsigned Flags,
+                                         MDType *Ty, MDNode *PropertyNode) {
+  return MDDerivedType::get(
+      VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(File)), MDTypeRef::get(Ty),
+      SizeInBits, AlignInBits, OffsetInBits, Flags, PropertyNode);
+}
+
+MDObjCProperty *
+DIBuilder::createObjCProperty(StringRef Name, MDFile *File, unsigned LineNumber,
+                              StringRef GetterName, StringRef SetterName,
+                              unsigned PropertyAttributes, MDType *Ty) {
+  return MDObjCProperty::get(VMContext, Name, File, LineNumber, GetterName,
+                             SetterName, PropertyAttributes, Ty);
+}
+
+MDTemplateTypeParameter *
+DIBuilder::createTemplateTypeParameter(MDScope *Context, StringRef Name,
+                                       MDType *Ty) {
+  assert((!Context || isa<MDCompileUnit>(Context)) && "Expected compile unit");
+  return MDTemplateTypeParameter::get(VMContext, Name, MDTypeRef::get(Ty));
+}
+
+static MDTemplateValueParameter *
+createTemplateValueParameterHelper(LLVMContext &VMContext, unsigned Tag,
+                                   MDScope *Context, StringRef Name, MDType *Ty,
+                                   Metadata *MD) {
+  assert((!Context || isa<MDCompileUnit>(Context)) && "Expected compile unit");
+  return MDTemplateValueParameter::get(VMContext, Tag, Name, MDTypeRef::get(Ty),
+                                       MD);
+}
+
+MDTemplateValueParameter *
+DIBuilder::createTemplateValueParameter(MDScope *Context, StringRef Name,
+                                        MDType *Ty, Constant *Val) {
+  return createTemplateValueParameterHelper(
+      VMContext, dwarf::DW_TAG_template_value_parameter, Context, Name, Ty,
+      getConstantOrNull(Val));
+}
+
+MDTemplateValueParameter *
+DIBuilder::createTemplateTemplateParameter(MDScope *Context, StringRef Name,
+                                           MDType *Ty, StringRef Val) {
+  return createTemplateValueParameterHelper(
+      VMContext, dwarf::DW_TAG_GNU_template_template_param, Context, Name, Ty,
+      MDString::get(VMContext, Val));
+}
+
+MDTemplateValueParameter *
+DIBuilder::createTemplateParameterPack(MDScope *Context, StringRef Name,
+                                       MDType *Ty, DebugNodeArray Val) {
+  return createTemplateValueParameterHelper(
+      VMContext, dwarf::DW_TAG_GNU_template_parameter_pack, Context, Name, Ty,
+      Val.get());
+}
+
+MDCompositeType *DIBuilder::createClassType(
+    MDScope *Context, StringRef Name, MDFile *File, unsigned LineNumber,
+    uint64_t SizeInBits, uint64_t AlignInBits, uint64_t OffsetInBits,
+    unsigned Flags, MDType *DerivedFrom, DebugNodeArray Elements,
+    MDType *VTableHolder, MDNode *TemplateParams, StringRef UniqueIdentifier) {
+  assert((!Context || isa<MDScope>(Context)) &&
          "createClassType should be called with a valid Context");
-  // TAG_class_type is encoded in DICompositeType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_class_type),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Context)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), OffsetInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    DerivedFrom.getRef(),
-    Elements,
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    VTableHolder.getRef(),
-    TemplateParams,
-    UniqueIdentifier.empty() ? nullptr
-                             : MDString::get(VMContext, UniqueIdentifier)
-  };
-  DICompositeType R(MDNode::get(VMContext, Elts));
-  assert(R.isCompositeType() &&
-         "createClassType should return a DICompositeType");
+
+  auto *R = MDCompositeType::get(
+      VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(Context)),
+      MDTypeRef::get(DerivedFrom), SizeInBits, AlignInBits, OffsetInBits, Flags,
+      Elements, 0, MDTypeRef::get(VTableHolder),
+      cast_or_null<MDTuple>(TemplateParams), UniqueIdentifier);
   if (!UniqueIdentifier.empty())
     retainType(R);
+  trackIfUnresolved(R);
   return R;
 }
 
-/// createStructType - Create debugging information entry for a struct.
-DICompositeType DIBuilder::createStructType(DIDescriptor Context,
-                                            StringRef Name, DIFile File,
-                                            unsigned LineNumber,
-                                            uint64_t SizeInBits,
-                                            uint64_t AlignInBits,
-                                            unsigned Flags, DIType DerivedFrom,
-                                            DIArray Elements,
-                                            unsigned RunTimeLang,
-                                            DIType VTableHolder,
-                                            StringRef UniqueIdentifier) {
- // TAG_structure_type is encoded in DICompositeType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_structure_type),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Context)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    DerivedFrom.getRef(),
-    Elements,
-    ConstantInt::get(Type::getInt32Ty(VMContext), RunTimeLang),
-    VTableHolder.getRef(),
-    nullptr,
-    UniqueIdentifier.empty() ? nullptr
-                             : MDString::get(VMContext, UniqueIdentifier)
-  };
-  DICompositeType R(MDNode::get(VMContext, Elts));
-  assert(R.isCompositeType() &&
-         "createStructType should return a DICompositeType");
+MDCompositeType *DIBuilder::createStructType(
+    MDScope *Context, StringRef Name, MDFile *File, unsigned LineNumber,
+    uint64_t SizeInBits, uint64_t AlignInBits, unsigned Flags,
+    MDType *DerivedFrom, DebugNodeArray Elements, unsigned RunTimeLang,
+    MDType *VTableHolder, StringRef UniqueIdentifier) {
+  auto *R = MDCompositeType::get(
+      VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(Context)),
+      MDTypeRef::get(DerivedFrom), SizeInBits, AlignInBits, 0, Flags, Elements,
+      RunTimeLang, MDTypeRef::get(VTableHolder), nullptr, UniqueIdentifier);
   if (!UniqueIdentifier.empty())
     retainType(R);
+  trackIfUnresolved(R);
   return R;
 }
 
-/// createUnionType - Create debugging information entry for an union.
-DICompositeType DIBuilder::createUnionType(DIDescriptor Scope, StringRef Name,
-                                           DIFile File, unsigned LineNumber,
-                                           uint64_t SizeInBits,
-                                           uint64_t AlignInBits, unsigned Flags,
-                                           DIArray Elements,
-                                           unsigned RunTimeLang,
-                                           StringRef UniqueIdentifier) {
-  // TAG_union_type is encoded in DICompositeType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_union_type),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Scope)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    nullptr,
-    Elements,
-    ConstantInt::get(Type::getInt32Ty(VMContext), RunTimeLang),
-    nullptr,
-    nullptr,
-    UniqueIdentifier.empty() ? nullptr
-                             : MDString::get(VMContext, UniqueIdentifier)
-  };
-  DICompositeType R(MDNode::get(VMContext, Elts));
+MDCompositeType *DIBuilder::createUnionType(
+    MDScope *Scope, StringRef Name, MDFile *File, unsigned LineNumber,
+    uint64_t SizeInBits, uint64_t AlignInBits, unsigned Flags,
+    DebugNodeArray Elements, unsigned RunTimeLang, StringRef UniqueIdentifier) {
+  auto *R = MDCompositeType::get(
+      VMContext, dwarf::DW_TAG_union_type, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(Scope)), nullptr, SizeInBits,
+      AlignInBits, 0, Flags, Elements, RunTimeLang, nullptr, nullptr,
+      UniqueIdentifier);
   if (!UniqueIdentifier.empty())
     retainType(R);
+  trackIfUnresolved(R);
   return R;
 }
 
-/// createSubroutineType - Create subroutine type.
-DISubroutineType DIBuilder::createSubroutineType(DIFile File,
-                                                 DITypeArray ParameterTypes,
-                                                 unsigned Flags) {
-  // TAG_subroutine_type is encoded in DICompositeType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_subroutine_type),
-    Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    nullptr,
-    MDString::get(VMContext, ""),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Size
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Align
-    ConstantInt::get(Type::getInt64Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags), // Flags
-    nullptr,
-    ParameterTypes,
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    nullptr,
-    nullptr,
-    nullptr  // Type Identifer
-  };
-  return DISubroutineType(MDNode::get(VMContext, Elts));
-}
-
-/// createEnumerationType - Create debugging information entry for an
-/// enumeration.
-DICompositeType DIBuilder::createEnumerationType(
-    DIDescriptor Scope, StringRef Name, DIFile File, unsigned LineNumber,
-    uint64_t SizeInBits, uint64_t AlignInBits, DIArray Elements,
-    DIType UnderlyingType, StringRef UniqueIdentifier) {
-  // TAG_enumeration_type is encoded in DICompositeType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_enumeration_type),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Scope)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    UnderlyingType.getRef(),
-    Elements,
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    nullptr,
-    nullptr,
-    UniqueIdentifier.empty() ? nullptr
-                             : MDString::get(VMContext, UniqueIdentifier)
-  };
-  DICompositeType CTy(MDNode::get(VMContext, Elts));
+MDSubroutineType *DIBuilder::createSubroutineType(MDFile *File,
+                                                  MDTypeRefArray ParameterTypes,
+                                                  unsigned Flags) {
+  return MDSubroutineType::get(VMContext, Flags, ParameterTypes);
+}
+
+MDCompositeType *DIBuilder::createEnumerationType(
+    MDScope *Scope, StringRef Name, MDFile *File, unsigned LineNumber,
+    uint64_t SizeInBits, uint64_t AlignInBits, DebugNodeArray Elements,
+    MDType *UnderlyingType, StringRef UniqueIdentifier) {
+  auto *CTy = MDCompositeType::get(
+      VMContext, dwarf::DW_TAG_enumeration_type, Name, File, LineNumber,
+      MDScopeRef::get(getNonCompileUnitScope(Scope)),
+      MDTypeRef::get(UnderlyingType), SizeInBits, AlignInBits, 0, 0, Elements,
+      0, nullptr, nullptr, UniqueIdentifier);
   AllEnumTypes.push_back(CTy);
   if (!UniqueIdentifier.empty())
     retainType(CTy);
+  trackIfUnresolved(CTy);
   return CTy;
 }
 
-/// createArrayType - Create debugging information entry for an array.
-DICompositeType DIBuilder::createArrayType(uint64_t Size, uint64_t AlignInBits,
-                                           DIType Ty, DIArray Subscripts) {
-  // TAG_array_type is encoded in DICompositeType format.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_array_type),
-    nullptr, // Filename/Directory,
-    nullptr, // Unused
-    MDString::get(VMContext, ""),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), Size),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Flags
-    Ty.getRef(),
-    Subscripts,
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    nullptr,
-    nullptr,
-    nullptr  // Type Identifer
-  };
-  return DICompositeType(MDNode::get(VMContext, Elts));
-}
-
-/// createVectorType - Create debugging information entry for a vector.
-DICompositeType DIBuilder::createVectorType(uint64_t Size, uint64_t AlignInBits,
-                                            DIType Ty, DIArray Subscripts) {
-  // A vector is an array type with the FlagVector flag applied.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_array_type),
-    nullptr, // Filename/Directory,
-    nullptr, // Unused
-    MDString::get(VMContext, ""),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Line
-    ConstantInt::get(Type::getInt64Ty(VMContext), Size),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), DIType::FlagVector),
-    Ty.getRef(),
-    Subscripts,
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    nullptr,
-    nullptr,
-    nullptr  // Type Identifer
-  };
-  return DICompositeType(MDNode::get(VMContext, Elts));
-}
-
-/// createArtificialType - Create a new DIType with "artificial" flag set.
-DIType DIBuilder::createArtificialType(DIType Ty) {
-  if (Ty.isArtificial())
-    return Ty;
-
-  SmallVector<Value *, 9> Elts;
-  MDNode *N = Ty;
-  assert (N && "Unexpected input DIType!");
-  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
-    Elts.push_back(N->getOperand(i));
-
-  unsigned CurFlags = Ty.getFlags();
-  CurFlags = CurFlags | DIType::FlagArtificial;
+MDCompositeType *DIBuilder::createArrayType(uint64_t Size, uint64_t AlignInBits,
+                                            MDType *Ty,
+                                            DebugNodeArray Subscripts) {
+  auto *R = MDCompositeType::get(VMContext, dwarf::DW_TAG_array_type, "",
+                                 nullptr, 0, nullptr, MDTypeRef::get(Ty), Size,
+                                 AlignInBits, 0, 0, Subscripts, 0, nullptr);
+  trackIfUnresolved(R);
+  return R;
+}
 
-  // Flags are stored at this slot.
-  // FIXME: Add an enum for this magic value.
-  Elts[8] =  ConstantInt::get(Type::getInt32Ty(VMContext), CurFlags);
+MDCompositeType *DIBuilder::createVectorType(uint64_t Size,
+                                             uint64_t AlignInBits, MDType *Ty,
+                                             DebugNodeArray Subscripts) {
+  auto *R =
+      MDCompositeType::get(VMContext, dwarf::DW_TAG_array_type, "", nullptr, 0,
+                           nullptr, MDTypeRef::get(Ty), Size, AlignInBits, 0,
+                           DebugNode::FlagVector, Subscripts, 0, nullptr);
+  trackIfUnresolved(R);
+  return R;
+}
 
-  return DIType(MDNode::get(VMContext, Elts));
+static MDType *createTypeWithFlags(LLVMContext &Context, MDType *Ty,
+                                   unsigned FlagsToSet) {
+  auto NewTy = Ty->clone();
+  NewTy->setFlags(NewTy->getFlags() | FlagsToSet);
+  return MDNode::replaceWithUniqued(std::move(NewTy));
 }
 
-/// createObjectPointerType - Create a new type with both the object pointer
-/// and artificial flags set.
-DIType DIBuilder::createObjectPointerType(DIType Ty) {
-  if (Ty.isObjectPointer())
+MDType *DIBuilder::createArtificialType(MDType *Ty) {
+  // FIXME: Restrict this to the nodes where it's valid.
+  if (Ty->isArtificial())
     return Ty;
-
-  SmallVector<Value *, 9> Elts;
-  MDNode *N = Ty;
-  assert (N && "Unexpected input DIType!");
-  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
-    Elts.push_back(N->getOperand(i));
-
-  unsigned CurFlags = Ty.getFlags();
-  CurFlags = CurFlags | (DIType::FlagObjectPointer | DIType::FlagArtificial);
-
-  // Flags are stored at this slot.
-  // FIXME: Add an enum for this magic value.
-  Elts[8] = ConstantInt::get(Type::getInt32Ty(VMContext), CurFlags);
-
-  return DIType(MDNode::get(VMContext, Elts));
+  return createTypeWithFlags(VMContext, Ty, DebugNode::FlagArtificial);
 }
 
-/// retainType - Retain DIType in a module even if it is not referenced
-/// through debug info anchors.
-void DIBuilder::retainType(DIType T) {
-  AllRetainTypes.push_back(TrackingVH<MDNode>(T));
+MDType *DIBuilder::createObjectPointerType(MDType *Ty) {
+  // FIXME: Restrict this to the nodes where it's valid.
+  if (Ty->isObjectPointer())
+    return Ty;
+  unsigned Flags = DebugNode::FlagObjectPointer | DebugNode::FlagArtificial;
+  return createTypeWithFlags(VMContext, Ty, Flags);
 }
 
-/// createUnspecifiedParameter - Create unspeicified type descriptor
-/// for the subroutine type.
-DIBasicType DIBuilder::createUnspecifiedParameter() {
-  return DIBasicType(nullptr);
+void DIBuilder::retainType(MDType *T) {
+  assert(T && "Expected non-null type");
+  AllRetainTypes.emplace_back(T);
 }
 
-/// createForwardDecl - Create a temporary forward-declared type that
-/// can be RAUW'd if the full type is seen.
-DICompositeType
-DIBuilder::createForwardDecl(unsigned Tag, StringRef Name, DIDescriptor Scope,
-                             DIFile F, unsigned Line, unsigned RuntimeLang,
+MDBasicType *DIBuilder::createUnspecifiedParameter() { return nullptr; }
+
+MDCompositeType*
+DIBuilder::createForwardDecl(unsigned Tag, StringRef Name, MDScope * Scope,
+                             MDFile* F, unsigned Line, unsigned RuntimeLang,
                              uint64_t SizeInBits, uint64_t AlignInBits,
                              StringRef UniqueIdentifier) {
-  // Create a temporary MDNode.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    F.getFileNode(),
-    DIScope(getNonCompileUnitScope(Scope)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Line),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), DIDescriptor::FlagFwdDecl),
-    nullptr,
-    DIArray(),
-    ConstantInt::get(Type::getInt32Ty(VMContext), RuntimeLang),
-    nullptr,
-    nullptr, //TemplateParams
-    UniqueIdentifier.empty() ? nullptr
-                             : MDString::get(VMContext, UniqueIdentifier)
-  };
-  MDNode *Node = MDNode::get(VMContext, Elts);
-  DICompositeType RetTy(Node);
-  assert(RetTy.isCompositeType() &&
-         "createForwardDecl result should be a DIType");
+  // FIXME: Define in terms of createReplaceableForwardDecl() by calling
+  // replaceWithUniqued().
+  auto *RetTy = MDCompositeType::get(
+      VMContext, Tag, Name, F, Line,
+      MDScopeRef::get(getNonCompileUnitScope(Scope)), nullptr, SizeInBits,
+      AlignInBits, 0, DebugNode::FlagFwdDecl, nullptr, RuntimeLang, nullptr,
+      nullptr, UniqueIdentifier);
   if (!UniqueIdentifier.empty())
     retainType(RetTy);
+  trackIfUnresolved(RetTy);
   return RetTy;
 }
 
-/// createForwardDecl - Create a temporary forward-declared type that
-/// can be RAUW'd if the full type is seen.
-DICompositeType DIBuilder::createReplaceableForwardDecl(
-    unsigned Tag, StringRef Name, DIDescriptor Scope, DIFile F, unsigned Line,
+MDCompositeType* DIBuilder::createReplaceableCompositeType(
+    unsigned Tag, StringRef Name, MDScope * Scope, MDFile* F, unsigned Line,
     unsigned RuntimeLang, uint64_t SizeInBits, uint64_t AlignInBits,
-    StringRef UniqueIdentifier) {
-  // Create a temporary MDNode.
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    F.getFileNode(),
-    DIScope(getNonCompileUnitScope(Scope)).getRef(),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Line),
-    ConstantInt::get(Type::getInt64Ty(VMContext), SizeInBits),
-    ConstantInt::get(Type::getInt64Ty(VMContext), AlignInBits),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0), // Offset
-    ConstantInt::get(Type::getInt32Ty(VMContext), DIDescriptor::FlagFwdDecl),
-    nullptr,
-    DIArray(),
-    ConstantInt::get(Type::getInt32Ty(VMContext), RuntimeLang),
-    nullptr,
-    nullptr, //TemplateParams
-    UniqueIdentifier.empty() ? nullptr
-                             : MDString::get(VMContext, UniqueIdentifier)
-  };
-  MDNode *Node = MDNode::getTemporary(VMContext, Elts);
-  DICompositeType RetTy(Node);
-  assert(RetTy.isCompositeType() &&
-         "createForwardDecl result should be a DIType");
+    unsigned Flags, StringRef UniqueIdentifier) {
+  auto *RetTy = MDCompositeType::getTemporary(
+                    VMContext, Tag, Name, F, Line,
+                    MDScopeRef::get(getNonCompileUnitScope(Scope)), nullptr,
+                    SizeInBits, AlignInBits, 0, Flags, nullptr, RuntimeLang,
+                    nullptr, nullptr, UniqueIdentifier).release();
   if (!UniqueIdentifier.empty())
     retainType(RetTy);
+  trackIfUnresolved(RetTy);
   return RetTy;
 }
 
-/// getOrCreateArray - Get a DIArray, create one if required.
-DIArray DIBuilder::getOrCreateArray(ArrayRef<Value *> Elements) {
-  return DIArray(MDNode::get(VMContext, Elements));
+DebugNodeArray DIBuilder::getOrCreateArray(ArrayRef<Metadata *> Elements) {
+  return MDTuple::get(VMContext, Elements);
 }
 
-/// getOrCreateTypeArray - Get a DITypeArray, create one if required.
-DITypeArray DIBuilder::getOrCreateTypeArray(ArrayRef<Value *> Elements) {
-  SmallVector<llvm::Value *, 16> Elts; 
+MDTypeRefArray DIBuilder::getOrCreateTypeArray(ArrayRef<Metadata *> Elements) {
+  SmallVector<llvm::Metadata *, 16> Elts;
   for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
     if (Elements[i] && isa<MDNode>(Elements[i]))
-      Elts.push_back(DIType(cast<MDNode>(Elements[i])).getRef());
+      Elts.push_back(MDTypeRef::get(cast<MDType>(Elements[i])));
     else
       Elts.push_back(Elements[i]);
   }
-  return DITypeArray(MDNode::get(VMContext, Elts));
-}
-
-/// getOrCreateSubrange - Create a descriptor for a value range.  This
-/// implicitly uniques the values returned.
-DISubrange DIBuilder::getOrCreateSubrange(int64_t Lo, int64_t Count) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_subrange_type),
-    ConstantInt::get(Type::getInt64Ty(VMContext), Lo),
-    ConstantInt::get(Type::getInt64Ty(VMContext), Count)
-  };
-
-  return DISubrange(MDNode::get(VMContext, Elts));
-}
-
-/// \brief Create a new descriptor for the specified global.
-DIGlobalVariable DIBuilder::createGlobalVariable(StringRef Name,
-                                                 StringRef LinkageName,
-                                                 DIFile F, unsigned LineNumber,
-                                                 DITypeRef Ty, bool isLocalToUnit,
-                                                 Value *Val) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_variable),
-    Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    nullptr, // TheCU,
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, LinkageName),
-    F,
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    Ty,
-    ConstantInt::get(Type::getInt32Ty(VMContext), isLocalToUnit),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 1), /* isDefinition*/
-    Val,
-    DIDescriptor()
-  };
-  MDNode *Node = MDNode::get(VMContext, Elts);
-  AllGVs.push_back(Node);
-  return DIGlobalVariable(Node);
-}
-
-/// \brief Create a new descriptor for the specified global.
-DIGlobalVariable DIBuilder::createGlobalVariable(StringRef Name, DIFile F,
-                                                 unsigned LineNumber,
-                                                 DITypeRef Ty,
-                                                 bool isLocalToUnit,
-                                                 Value *Val) {
-  return createGlobalVariable(Name, Name, F, LineNumber, Ty, isLocalToUnit,
-                              Val);
-}
-
-/// createStaticVariable - Create a new descriptor for the specified static
-/// variable.
-DIGlobalVariable DIBuilder::createStaticVariable(DIDescriptor Context,
-                                                 StringRef Name,
-                                                 StringRef LinkageName,
-                                                 DIFile F, unsigned LineNumber,
-                                                 DITypeRef Ty,
-                                                 bool isLocalToUnit,
-                                                 Value *Val, MDNode *Decl) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_variable),
-    Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    getNonCompileUnitScope(Context),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, LinkageName),
-    F,
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNumber),
-    Ty,
-    ConstantInt::get(Type::getInt32Ty(VMContext), isLocalToUnit),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 1), /* isDefinition*/
-    Val,
-    DIDescriptor(Decl)
-  };
-  MDNode *Node = MDNode::get(VMContext, Elts);
-  AllGVs.push_back(Node);
-  return DIGlobalVariable(Node);
-}
-
-/// createVariable - Create a new descriptor for the specified variable.
-DIVariable DIBuilder::createLocalVariable(unsigned Tag, DIDescriptor Scope,
-                                          StringRef Name, DIFile File,
-                                          unsigned LineNo, DITypeRef Ty,
-                                          bool AlwaysPreserve, unsigned Flags,
-                                          unsigned ArgNo) {
-  DIDescriptor Context(getNonCompileUnitScope(Scope));
-  assert((!Context || Context.isScope()) &&
-         "createLocalVariable should be called with a valid Context");
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    getNonCompileUnitScope(Scope),
-    MDString::get(VMContext, Name),
-    File,
-    ConstantInt::get(Type::getInt32Ty(VMContext), (LineNo | (ArgNo << 24))),
-    Ty,
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    Constant::getNullValue(Type::getInt32Ty(VMContext))
-  };
-  MDNode *Node = MDNode::get(VMContext, Elts);
+  return MDTypeRefArray(MDNode::get(VMContext, Elts));
+}
+
+MDSubrange *DIBuilder::getOrCreateSubrange(int64_t Lo, int64_t Count) {
+  return MDSubrange::get(VMContext, Count, Lo);
+}
+
+static void checkGlobalVariableScope(MDScope * Context) {
+#ifndef NDEBUG
+  if (auto *CT =
+          dyn_cast_or_null<MDCompositeType>(getNonCompileUnitScope(Context)))
+    assert(CT->getIdentifier().empty() &&
+           "Context of a global variable should not be a type with identifier");
+#endif
+}
+
+MDGlobalVariable *DIBuilder::createGlobalVariable(
+    MDScope *Context, StringRef Name, StringRef LinkageName, MDFile *F,
+    unsigned LineNumber, MDType *Ty, bool isLocalToUnit, Constant *Val,
+    MDNode *Decl) {
+  checkGlobalVariableScope(Context);
+
+  auto *N = MDGlobalVariable::get(VMContext, cast_or_null<MDScope>(Context),
+                                  Name, LinkageName, F, LineNumber,
+                                  MDTypeRef::get(Ty), isLocalToUnit, true, Val,
+                                  cast_or_null<MDDerivedType>(Decl));
+  AllGVs.push_back(N);
+  return N;
+}
+
+MDGlobalVariable *DIBuilder::createTempGlobalVariableFwdDecl(
+    MDScope *Context, StringRef Name, StringRef LinkageName, MDFile *F,
+    unsigned LineNumber, MDType *Ty, bool isLocalToUnit, Constant *Val,
+    MDNode *Decl) {
+  checkGlobalVariableScope(Context);
+
+  return MDGlobalVariable::getTemporary(
+             VMContext, cast_or_null<MDScope>(Context), Name, LinkageName, F,
+             LineNumber, MDTypeRef::get(Ty), isLocalToUnit, false, Val,
+             cast_or_null<MDDerivedType>(Decl))
+      .release();
+}
+
+MDLocalVariable *DIBuilder::createLocalVariable(
+    unsigned Tag, MDScope *Scope, StringRef Name, MDFile *File, unsigned LineNo,
+    MDType *Ty, bool AlwaysPreserve, unsigned Flags, unsigned ArgNo) {
+  // FIXME: Why getNonCompileUnitScope()?
+  // FIXME: Why is "!Context" okay here?
+  // FIXME: WHy doesn't this check for a subprogram or lexical block (AFAICT
+  // the only valid scopes)?
+  MDScope* Context = getNonCompileUnitScope(Scope);
+
+  auto *Node = MDLocalVariable::get(
+      VMContext, Tag, cast_or_null<MDLocalScope>(Context), Name, File, LineNo,
+      MDTypeRef::get(Ty), ArgNo, Flags);
   if (AlwaysPreserve) {
     // The optimizer may remove local variable. If there is an interest
     // to preserve variable info in such situation then stash it in a
     // named mdnode.
-    DISubprogram Fn(getDISubprogram(Scope));
-    NamedMDNode *FnLocals = getOrInsertFnSpecificMDNode(M, Fn);
-    FnLocals->addOperand(Node);
+    MDSubprogram *Fn = getDISubprogram(Scope);
+    assert(Fn && "Missing subprogram for local variable");
+    PreservedVariables[Fn].emplace_back(Node);
   }
-  DIVariable RetVar(Node);
-  assert(RetVar.isVariable() &&
-         "createLocalVariable should return a valid DIVariable");
-  return RetVar;
-}
-
-/// createComplexVariable - Create a new descriptor for the specified variable
-/// which has a complex address expression for its address.
-DIVariable DIBuilder::createComplexVariable(unsigned Tag, DIDescriptor Scope,
-                                            StringRef Name, DIFile F,
-                                            unsigned LineNo,
-                                            DITypeRef Ty,
-                                            ArrayRef<Value *> Addr,
-                                            unsigned ArgNo) {
-  assert(Addr.size() > 0 && "complex address is empty");
-  Value *Elts[] = {
-    GetTagConstant(VMContext, Tag),
-    getNonCompileUnitScope(Scope),
-    MDString::get(VMContext, Name),
-    F,
-    ConstantInt::get(Type::getInt32Ty(VMContext),
-                     (LineNo | (ArgNo << 24))),
-    Ty,
-    Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    MDNode::get(VMContext, Addr)
-  };
-  return DIVariable(MDNode::get(VMContext, Elts));
-}
-
-/// createFunction - Create a new descriptor for the specified function.
-/// FIXME: this is added for dragonegg. Once we update dragonegg
-/// to call resolve function, this will be removed.
-DISubprogram DIBuilder::createFunction(DIScopeRef Context, StringRef Name,
-                                       StringRef LinkageName, DIFile File,
-                                       unsigned LineNo, DICompositeType Ty,
-                                       bool isLocalToUnit, bool isDefinition,
-                                       unsigned ScopeLine, unsigned Flags,
-                                       bool isOptimized, Function *Fn,
-                                       MDNode *TParams, MDNode *Decl) {
+  return Node;
+}
+
+MDExpression* DIBuilder::createExpression(ArrayRef<uint64_t> Addr) {
+  return MDExpression::get(VMContext, Addr);
+}
+
+MDExpression* DIBuilder::createExpression(ArrayRef<int64_t> Signed) {
+  // TODO: Remove the callers of this signed version and delete.
+  SmallVector<uint64_t, 8> Addr(Signed.begin(), Signed.end());
+  return createExpression(Addr);
+}
+
+MDExpression* DIBuilder::createBitPieceExpression(unsigned OffsetInBytes,
+                                                 unsigned SizeInBytes) {
+  uint64_t Addr[] = {dwarf::DW_OP_bit_piece, OffsetInBytes, SizeInBytes};
+  return MDExpression::get(VMContext, Addr);
+}
+
+MDSubprogram *DIBuilder::createFunction(MDScopeRef Context, StringRef Name,
+                                        StringRef LinkageName, MDFile *File,
+                                        unsigned LineNo, MDSubroutineType *Ty,
+                                        bool isLocalToUnit, bool isDefinition,
+                                        unsigned ScopeLine, unsigned Flags,
+                                        bool isOptimized, Function *Fn,
+                                        MDNode *TParams, MDNode *Decl) {
   // dragonegg does not generate identifier for types, so using an empty map
   // to resolve the context should be fine.
   DITypeIdentifierMap EmptyMap;
@@ -1118,215 +635,227 @@ DISubprogram DIBuilder::createFunction(DIScopeRef Context, StringRef Name,
                         Flags, isOptimized, Fn, TParams, Decl);
 }
 
-/// createFunction - Create a new descriptor for the specified function.
-DISubprogram DIBuilder::createFunction(DIDescriptor Context, StringRef Name,
-                                       StringRef LinkageName, DIFile File,
-                                       unsigned LineNo, DICompositeType Ty,
+MDSubprogram* DIBuilder::createFunction(MDScope * Context, StringRef Name,
+                                       StringRef LinkageName, MDFile* File,
+                                       unsigned LineNo, MDSubroutineType* Ty,
                                        bool isLocalToUnit, bool isDefinition,
                                        unsigned ScopeLine, unsigned Flags,
                                        bool isOptimized, Function *Fn,
                                        MDNode *TParams, MDNode *Decl) {
-  assert(Ty.getTag() == dwarf::DW_TAG_subroutine_type &&
+  assert(Ty->getTag() == dwarf::DW_TAG_subroutine_type &&
          "function types should be subroutines");
-  Value *TElts[] = { GetTagConstant(VMContext, DW_TAG_base_type) };
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_subprogram),
-    File.getFileNode(),
-    DIScope(getNonCompileUnitScope(Context)).getRef(),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, LinkageName),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
-    Ty,
-    ConstantInt::get(Type::getInt1Ty(VMContext), isLocalToUnit),
-    ConstantInt::get(Type::getInt1Ty(VMContext), isDefinition),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    ConstantInt::get(Type::getInt32Ty(VMContext), 0),
-    nullptr,
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    ConstantInt::get(Type::getInt1Ty(VMContext), isOptimized),
-    Fn,
-    TParams,
-    Decl,
-    MDNode::getTemporary(VMContext, TElts),
-    ConstantInt::get(Type::getInt32Ty(VMContext), ScopeLine)
-  };
-  MDNode *Node = MDNode::get(VMContext, Elts);
-
-  // Create a named metadata so that we do not lose this mdnode.
+  auto *Node = MDSubprogram::get(
+      VMContext, MDScopeRef::get(getNonCompileUnitScope(Context)), Name,
+      LinkageName, File, LineNo, Ty,
+      isLocalToUnit, isDefinition, ScopeLine, nullptr, 0, 0, Flags, isOptimized,
+      Fn, cast_or_null<MDTuple>(TParams), cast_or_null<MDSubprogram>(Decl),
+      MDTuple::getTemporary(VMContext, None).release());
+
   if (isDefinition)
     AllSubprograms.push_back(Node);
-  DISubprogram S(Node);
-  assert(S.isSubprogram() &&
-         "createFunction should return a valid DISubprogram");
-  return S;
+  trackIfUnresolved(Node);
+  return Node;
 }
 
-/// createMethod - Create a new descriptor for the specified C++ method.
-DISubprogram DIBuilder::createMethod(DIDescriptor Context, StringRef Name,
-                                     StringRef LinkageName, DIFile F,
-                                     unsigned LineNo, DICompositeType Ty,
+MDSubprogram*
+DIBuilder::createTempFunctionFwdDecl(MDScope * Context, StringRef Name,
+                                     StringRef LinkageName, MDFile* File,
+                                     unsigned LineNo, MDSubroutineType* Ty,
                                      bool isLocalToUnit, bool isDefinition,
-                                     unsigned VK, unsigned VIndex,
-                                     DIType VTableHolder, unsigned Flags,
+                                     unsigned ScopeLine, unsigned Flags,
                                      bool isOptimized, Function *Fn,
-                                     MDNode *TParam) {
-  assert(Ty.getTag() == dwarf::DW_TAG_subroutine_type &&
+                                     MDNode *TParams, MDNode *Decl) {
+  return MDSubprogram::getTemporary(
+             VMContext, MDScopeRef::get(getNonCompileUnitScope(Context)), Name,
+             LinkageName, File, LineNo, Ty,
+             isLocalToUnit, isDefinition, ScopeLine, nullptr, 0, 0, Flags,
+             isOptimized, Fn, cast_or_null<MDTuple>(TParams),
+             cast_or_null<MDSubprogram>(Decl), nullptr).release();
+}
+
+MDSubprogram *
+DIBuilder::createMethod(MDScope *Context, StringRef Name, StringRef LinkageName,
+                        MDFile *F, unsigned LineNo, MDSubroutineType *Ty,
+                        bool isLocalToUnit, bool isDefinition, unsigned VK,
+                        unsigned VIndex, MDType *VTableHolder, unsigned Flags,
+                        bool isOptimized, Function *Fn, MDNode *TParam) {
+  assert(Ty->getTag() == dwarf::DW_TAG_subroutine_type &&
          "function types should be subroutines");
   assert(getNonCompileUnitScope(Context) &&
          "Methods should have both a Context and a context that isn't "
          "the compile unit.");
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_subprogram),
-    F.getFileNode(),
-    DIScope(Context).getRef(),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, Name),
-    MDString::get(VMContext, LinkageName),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
-    Ty,
-    ConstantInt::get(Type::getInt1Ty(VMContext), isLocalToUnit),
-    ConstantInt::get(Type::getInt1Ty(VMContext), isDefinition),
-    ConstantInt::get(Type::getInt32Ty(VMContext), VK),
-    ConstantInt::get(Type::getInt32Ty(VMContext), VIndex),
-    VTableHolder.getRef(),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Flags),
-    ConstantInt::get(Type::getInt1Ty(VMContext), isOptimized),
-    Fn,
-    TParam,
-    Constant::getNullValue(Type::getInt32Ty(VMContext)),
-    nullptr,
-    // FIXME: Do we want to use different scope/lines?
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo)
-  };
-  MDNode *Node = MDNode::get(VMContext, Elts);
+  // FIXME: Do we want to use different scope/lines?
+  auto *SP = MDSubprogram::get(
+      VMContext, MDScopeRef::get(cast<MDScope>(Context)), Name, LinkageName, F,
+      LineNo, Ty, isLocalToUnit, isDefinition, LineNo,
+      MDTypeRef::get(VTableHolder), VK, VIndex, Flags, isOptimized, Fn,
+      cast_or_null<MDTuple>(TParam), nullptr, nullptr);
+
   if (isDefinition)
-    AllSubprograms.push_back(Node);
-  DISubprogram S(Node);
-  assert(S.isSubprogram() && "createMethod should return a valid DISubprogram");
-  return S;
-}
-
-/// createNameSpace - This creates new descriptor for a namespace
-/// with the specified parent scope.
-DINameSpace DIBuilder::createNameSpace(DIDescriptor Scope, StringRef Name,
-                                       DIFile File, unsigned LineNo) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_namespace),
-    File.getFileNode(),
-    getNonCompileUnitScope(Scope),
-    MDString::get(VMContext, Name),
-    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo)
-  };
-  DINameSpace R(MDNode::get(VMContext, Elts));
-  assert(R.Verify() &&
-         "createNameSpace should return a verifiable DINameSpace");
-  return R;
+    AllSubprograms.push_back(SP);
+  trackIfUnresolved(SP);
+  return SP;
 }
 
-/// createLexicalBlockFile - This creates a new MDNode that encapsulates
-/// an existing scope with a new filename.
-DILexicalBlockFile DIBuilder::createLexicalBlockFile(DIDescriptor Scope,
-                                                     DIFile File) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_lexical_block),
-    File.getFileNode(),
-    Scope
-  };
-  DILexicalBlockFile R(MDNode::get(VMContext, Elts));
-  assert(
-      R.Verify() &&
-      "createLexicalBlockFile should return a verifiable DILexicalBlockFile");
-  return R;
+MDNamespace* DIBuilder::createNameSpace(MDScope * Scope, StringRef Name,
+                                       MDFile* File, unsigned LineNo) {
+  return MDNamespace::get(VMContext, getNonCompileUnitScope(Scope), File, Name,
+                          LineNo);
 }
 
-DILexicalBlock DIBuilder::createLexicalBlock(DIDescriptor Scope, DIFile File,
-                                             unsigned Line, unsigned Col,
-                                             unsigned Discriminator) {
-  // FIXME: This isn't thread safe nor the right way to defeat MDNode uniquing.
-  // I believe the right way is to have a self-referential element in the node.
-  // Also: why do we bother with line/column - they're not used and the
-  // documentation (SourceLevelDebugging.rst) claims the line/col are necessary
-  // for uniquing, yet then we have this other solution (because line/col were
-  // inadequate) anyway. Remove all 3 and replace them with a self-reference.
-
-  // Defeat MDNode uniquing for lexical blocks by using unique id.
-  static unsigned int unique_id = 0;
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_lexical_block),
-    File.getFileNode(),
-    getNonCompileUnitScope(Scope),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Line),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Col),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Discriminator),
-    ConstantInt::get(Type::getInt32Ty(VMContext), unique_id++)
-  };
-  DILexicalBlock R(MDNode::get(VMContext, Elts));
-  assert(R.Verify() &&
-         "createLexicalBlock should return a verifiable DILexicalBlock");
-  return R;
+MDLexicalBlockFile* DIBuilder::createLexicalBlockFile(MDScope * Scope,
+                                                     MDFile* File,
+                                                     unsigned Discriminator) {
+  return MDLexicalBlockFile::get(VMContext, Scope, File, Discriminator);
+}
+
+MDLexicalBlock* DIBuilder::createLexicalBlock(MDScope * Scope, MDFile* File,
+                                             unsigned Line, unsigned Col) {
+  // Make these distinct, to avoid merging two lexical blocks on the same
+  // file/line/column.
+  return MDLexicalBlock::getDistinct(VMContext, getNonCompileUnitScope(Scope),
+                                     File, Line, Col);
+}
+
+static Value *getDbgIntrinsicValueImpl(LLVMContext &VMContext, Value *V) {
+  assert(V && "no value passed to dbg intrinsic");
+  return MetadataAsValue::get(VMContext, ValueAsMetadata::get(V));
+}
+
+static Instruction *withDebugLoc(Instruction *I, const MDLocation *DL) {
+  I->setDebugLoc(const_cast<MDLocation *>(DL));
+  return I;
 }
 
-/// insertDeclare - Insert a new llvm.dbg.declare intrinsic call.
-Instruction *DIBuilder::insertDeclare(Value *Storage, DIVariable VarInfo,
+Instruction *DIBuilder::insertDeclare(Value *Storage, MDLocalVariable* VarInfo,
+                                      MDExpression* Expr, const MDLocation *DL,
                                       Instruction *InsertBefore) {
-  assert(Storage && "no storage passed to dbg.declare");
-  assert(VarInfo.isVariable() &&
-         "empty or invalid DIVariable passed to dbg.declare");
+  assert(VarInfo && "empty or invalid MDLocalVariable* passed to dbg.declare");
+  assert(DL && "Expected debug loc");
+  assert(DL->getScope()->getSubprogram() ==
+             VarInfo->getScope()->getSubprogram() &&
+         "Expected matching subprograms");
   if (!DeclareFn)
     DeclareFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_declare);
 
-  Value *Args[] = { MDNode::get(Storage->getContext(), Storage), VarInfo };
-  return CallInst::Create(DeclareFn, Args, "", InsertBefore);
+  trackIfUnresolved(VarInfo);
+  trackIfUnresolved(Expr);
+  Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, Storage),
+                   MetadataAsValue::get(VMContext, VarInfo),
+                   MetadataAsValue::get(VMContext, Expr)};
+  return withDebugLoc(CallInst::Create(DeclareFn, Args, "", InsertBefore), DL);
 }
 
-/// insertDeclare - Insert a new llvm.dbg.declare intrinsic call.
-Instruction *DIBuilder::insertDeclare(Value *Storage, DIVariable VarInfo,
+Instruction *DIBuilder::insertDeclare(Value *Storage, MDLocalVariable* VarInfo,
+                                      MDExpression* Expr, const MDLocation *DL,
                                       BasicBlock *InsertAtEnd) {
-  assert(Storage && "no storage passed to dbg.declare");
-  assert(VarInfo.isVariable() &&
-         "empty or invalid DIVariable passed to dbg.declare");
+  assert(VarInfo && "empty or invalid MDLocalVariable* passed to dbg.declare");
+  assert(DL && "Expected debug loc");
+  assert(DL->getScope()->getSubprogram() ==
+             VarInfo->getScope()->getSubprogram() &&
+         "Expected matching subprograms");
   if (!DeclareFn)
     DeclareFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_declare);
 
-  Value *Args[] = { MDNode::get(Storage->getContext(), Storage), VarInfo };
+  trackIfUnresolved(VarInfo);
+  trackIfUnresolved(Expr);
+  Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, Storage),
+                   MetadataAsValue::get(VMContext, VarInfo),
+                   MetadataAsValue::get(VMContext, Expr)};
 
   // If this block already has a terminator then insert this intrinsic
   // before the terminator.
   if (TerminatorInst *T = InsertAtEnd->getTerminator())
-    return CallInst::Create(DeclareFn, Args, "", T);
-  else
-    return CallInst::Create(DeclareFn, Args, "", InsertAtEnd);
+    return withDebugLoc(CallInst::Create(DeclareFn, Args, "", T), DL);
+  return withDebugLoc(CallInst::Create(DeclareFn, Args, "", InsertAtEnd), DL);
 }
 
-/// insertDbgValueIntrinsic - Insert a new llvm.dbg.value intrinsic call.
 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V, uint64_t Offset,
-                                                DIVariable VarInfo,
+                                                MDLocalVariable* VarInfo,
+                                                MDExpression* Expr,
+                                                const MDLocation *DL,
                                                 Instruction *InsertBefore) {
   assert(V && "no value passed to dbg.value");
-  assert(VarInfo.isVariable() &&
-         "empty or invalid DIVariable passed to dbg.value");
+  assert(VarInfo && "empty or invalid MDLocalVariable* passed to dbg.value");
+  assert(DL && "Expected debug loc");
+  assert(DL->getScope()->getSubprogram() ==
+             VarInfo->getScope()->getSubprogram() &&
+         "Expected matching subprograms");
   if (!ValueFn)
     ValueFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_value);
 
-  Value *Args[] = { MDNode::get(V->getContext(), V),
-                    ConstantInt::get(Type::getInt64Ty(V->getContext()), Offset),
-                    VarInfo };
-  return CallInst::Create(ValueFn, Args, "", InsertBefore);
+  trackIfUnresolved(VarInfo);
+  trackIfUnresolved(Expr);
+  Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, V),
+                   ConstantInt::get(Type::getInt64Ty(VMContext), Offset),
+                   MetadataAsValue::get(VMContext, VarInfo),
+                   MetadataAsValue::get(VMContext, Expr)};
+  return withDebugLoc(CallInst::Create(ValueFn, Args, "", InsertBefore), DL);
 }
 
-/// insertDbgValueIntrinsic - Insert a new llvm.dbg.value intrinsic call.
 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V, uint64_t Offset,
-                                                DIVariable VarInfo,
+                                                MDLocalVariable* VarInfo,
+                                                MDExpression* Expr,
+                                                const MDLocation *DL,
                                                 BasicBlock *InsertAtEnd) {
   assert(V && "no value passed to dbg.value");
-  assert(VarInfo.isVariable() &&
-         "empty or invalid DIVariable passed to dbg.value");
+  assert(VarInfo && "empty or invalid MDLocalVariable* passed to dbg.value");
+  assert(DL && "Expected debug loc");
+  assert(DL->getScope()->getSubprogram() ==
+             VarInfo->getScope()->getSubprogram() &&
+         "Expected matching subprograms");
   if (!ValueFn)
     ValueFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_value);
 
-  Value *Args[] = { MDNode::get(V->getContext(), V),
-                    ConstantInt::get(Type::getInt64Ty(V->getContext()), Offset),
-                    VarInfo };
-  return CallInst::Create(ValueFn, Args, "", InsertAtEnd);
+  trackIfUnresolved(VarInfo);
+  trackIfUnresolved(Expr);
+  Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, V),
+                   ConstantInt::get(Type::getInt64Ty(VMContext), Offset),
+                   MetadataAsValue::get(VMContext, VarInfo),
+                   MetadataAsValue::get(VMContext, Expr)};
+
+  return withDebugLoc(CallInst::Create(ValueFn, Args, "", InsertAtEnd), DL);
+}
+
+void DIBuilder::replaceVTableHolder(MDCompositeType* &T, MDCompositeType* VTableHolder) {
+  {
+    TypedTrackingMDRef<MDCompositeType> N(T);
+    N->replaceVTableHolder(MDTypeRef::get(VTableHolder));
+    T = N.get();
+  }
+
+  // If this didn't create a self-reference, just return.
+  if (T != VTableHolder)
+    return;
+
+  // Look for unresolved operands.  T will drop RAUW support, orphaning any
+  // cycles underneath it.
+  if (T->isResolved())
+    for (const MDOperand &O : T->operands())
+      if (auto *N = dyn_cast_or_null<MDNode>(O))
+        trackIfUnresolved(N);
+}
+
+void DIBuilder::replaceArrays(MDCompositeType *&T, DebugNodeArray Elements,
+                              DebugNodeArray TParams) {
+  {
+    TypedTrackingMDRef<MDCompositeType> N(T);
+    if (Elements)
+      N->replaceElements(Elements);
+    if (TParams)
+      N->replaceTemplateParams(MDTemplateParameterArray(TParams));
+    T = N.get();
+  }
+
+  // If T isn't resolved, there's no problem.
+  if (!T->isResolved())
+    return;
+
+  // If "T" is resolved, it may be due to a self-reference cycle.  Track the
+  // arrays explicitly if they're unresolved, or else the cycles will be
+  // orphaned.
+  if (Elements)
+    trackIfUnresolved(Elements.get());
+  if (TParams)
+    trackIfUnresolved(TParams.get());
 }