Index: clang-tools-extra/trunk/clangd/AST.h
===================================================================
--- clang-tools-extra/trunk/clangd/AST.h
+++ clang-tools-extra/trunk/clangd/AST.h
@@ -13,9 +13,10 @@
 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_AST_H_
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_AST_H_
 
-#include "index/Index.h"
+#include "index/SymbolID.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/SourceLocation.h"
+#include "clang/Lex/MacroInfo.h"
 
 namespace clang {
 class SourceManager;
Index: clang-tools-extra/trunk/clangd/CMakeLists.txt
===================================================================
--- clang-tools-extra/trunk/clangd/CMakeLists.txt
+++ clang-tools-extra/trunk/clangd/CMakeLists.txt
@@ -62,6 +62,7 @@
   index/IndexAction.cpp
   index/MemIndex.cpp
   index/Merge.cpp
+  index/Ref.cpp
   index/Serialization.cpp
   index/Symbol.cpp
   index/SymbolCollector.cpp
Index: clang-tools-extra/trunk/clangd/IncludeFixer.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/IncludeFixer.cpp
+++ clang-tools-extra/trunk/clangd/IncludeFixer.cpp
@@ -24,6 +24,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TokenKinds.h"
+#include "clang/Lex/Lexer.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
Index: clang-tools-extra/trunk/clangd/Protocol.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/Protocol.cpp
+++ clang-tools-extra/trunk/clangd/Protocol.cpp
@@ -13,7 +13,6 @@
 #include "Protocol.h"
 #include "Logger.h"
 #include "URI.h"
-#include "index/Index.h"
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/SmallString.h"
Index: clang-tools-extra/trunk/clangd/Quality.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/Quality.cpp
+++ clang-tools-extra/trunk/clangd/Quality.cpp
@@ -5,11 +5,12 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+
 #include "Quality.h"
 #include "AST.h"
 #include "FileDistance.h"
 #include "URI.h"
-#include "index/Index.h"
+#include "index/Symbol.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
Index: clang-tools-extra/trunk/clangd/index/Index.h
===================================================================
--- clang-tools-extra/trunk/clangd/index/Index.h
+++ clang-tools-extra/trunk/clangd/index/Index.h
@@ -9,116 +9,19 @@
 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_INDEX_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_INDEX_H
 
-#include "ExpectedTypes.h"
+#include "Ref.h"
 #include "Symbol.h"
 #include "SymbolID.h"
-#include "SymbolLocation.h"
-#include "clang/Index/IndexSymbol.h"
-#include "clang/Lex/Lexer.h"
-#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Optional.h"
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
-#include "llvm/ADT/StringRef.h"
 #include "llvm/Support/JSON.h"
-#include <array>
-#include <limits>
 #include <mutex>
 #include <string>
-#include <tuple>
 
 namespace clang {
 namespace clangd {
 
-// Describes the kind of a cross-reference.
-//
-// This is a bitfield which can be combined from different kinds.
-enum class RefKind : uint8_t {
-  Unknown = 0,
-  Declaration = static_cast<uint8_t>(index::SymbolRole::Declaration),
-  Definition = static_cast<uint8_t>(index::SymbolRole::Definition),
-  Reference = static_cast<uint8_t>(index::SymbolRole::Reference),
-  All = Declaration | Definition | Reference,
-};
-inline RefKind operator|(RefKind L, RefKind R) {
-  return static_cast<RefKind>(static_cast<uint8_t>(L) |
-                              static_cast<uint8_t>(R));
-}
-inline RefKind &operator|=(RefKind &L, RefKind R) { return L = L | R; }
-inline RefKind operator&(RefKind A, RefKind B) {
-  return static_cast<RefKind>(static_cast<uint8_t>(A) &
-                              static_cast<uint8_t>(B));
-}
-llvm::raw_ostream &operator<<(llvm::raw_ostream &, RefKind);
-
-// Represents a symbol occurrence in the source file.
-// Despite the name, it could be a declaration/definition/reference.
-//
-// WARNING: Location does not own the underlying data - Copies are shallow.
-struct Ref {
-  // The source location where the symbol is named.
-  SymbolLocation Location;
-  RefKind Kind = RefKind::Unknown;
-};
-inline bool operator<(const Ref &L, const Ref &R) {
-  return std::tie(L.Location, L.Kind) < std::tie(R.Location, R.Kind);
-}
-inline bool operator==(const Ref &L, const Ref &R) {
-  return std::tie(L.Location, L.Kind) == std::tie(R.Location, R.Kind);
-}
-llvm::raw_ostream &operator<<(llvm::raw_ostream &, const Ref &);
-
-// An efficient structure of storing large set of symbol references in memory.
-// Filenames are deduplicated.
-class RefSlab {
-public:
-  using value_type = std::pair<SymbolID, llvm::ArrayRef<Ref>>;
-  using const_iterator = std::vector<value_type>::const_iterator;
-  using iterator = const_iterator;
-
-  RefSlab() = default;
-  RefSlab(RefSlab &&Slab) = default;
-  RefSlab &operator=(RefSlab &&RHS) = default;
-
-  const_iterator begin() const { return Refs.begin(); }
-  const_iterator end() const { return Refs.end(); }
-  /// Gets the number of symbols.
-  size_t size() const { return Refs.size(); }
-  size_t numRefs() const { return NumRefs; }
-  bool empty() const { return Refs.empty(); }
-
-  size_t bytes() const {
-    return sizeof(*this) + Arena.getTotalMemory() +
-           sizeof(value_type) * Refs.size();
-  }
-
-  // RefSlab::Builder is a mutable container that can 'freeze' to RefSlab.
-  class Builder {
-  public:
-    Builder() : UniqueStrings(Arena) {}
-    // Adds a ref to the slab. Deep copy: Strings will be owned by the slab.
-    void insert(const SymbolID &ID, const Ref &S);
-    // Consumes the builder to finalize the slab.
-    RefSlab build() &&;
-
-  private:
-    llvm::BumpPtrAllocator Arena;
-    llvm::UniqueStringSaver UniqueStrings; // Contents on the arena.
-    llvm::DenseMap<SymbolID, std::vector<Ref>> Refs;
-  };
-
-private:
-  RefSlab(std::vector<value_type> Refs, llvm::BumpPtrAllocator Arena,
-          size_t NumRefs)
-      : Arena(std::move(Arena)), Refs(std::move(Refs)), NumRefs(NumRefs) {}
-
-  llvm::BumpPtrAllocator Arena;
-  std::vector<value_type> Refs;
-  // Number of all references.
-  size_t NumRefs = 0;
-};
-
 struct FuzzyFindRequest {
   /// \brief A query string for the fuzzy find. This is matched against symbols'
   /// un-qualified identifiers and should not contain qualifiers like "::".
Index: clang-tools-extra/trunk/clangd/index/Index.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/index/Index.cpp
+++ clang-tools-extra/trunk/clangd/index/Index.cpp
@@ -12,57 +12,11 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_ostream.h"
+#include <limits>
 
 namespace clang {
 namespace clangd {
 
-llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, RefKind K) {
-  if (K == RefKind::Unknown)
-    return OS << "Unknown";
-  static const std::vector<const char *> Messages = {"Decl", "Def", "Ref"};
-  bool VisitedOnce = false;
-  for (unsigned I = 0; I < Messages.size(); ++I) {
-    if (static_cast<uint8_t>(K) & 1u << I) {
-      if (VisitedOnce)
-        OS << ", ";
-      OS << Messages[I];
-      VisitedOnce = true;
-    }
-  }
-  return OS;
-}
-
-llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Ref &R) {
-  return OS << R.Location << ":" << R.Kind;
-}
-
-void RefSlab::Builder::insert(const SymbolID &ID, const Ref &S) {
-  auto &M = Refs[ID];
-  M.push_back(S);
-  M.back().Location.FileURI =
-      UniqueStrings.save(M.back().Location.FileURI).data();
-}
-
-RefSlab RefSlab::Builder::build() && {
-  // We can reuse the arena, as it only has unique strings and we need them all.
-  // Reallocate refs on the arena to reduce waste and indirections when reading.
-  std::vector<std::pair<SymbolID, llvm::ArrayRef<Ref>>> Result;
-  Result.reserve(Refs.size());
-  size_t NumRefs = 0;
-  for (auto &Sym : Refs) {
-    auto &SymRefs = Sym.second;
-    llvm::sort(SymRefs);
-    // FIXME: do we really need to dedup?
-    SymRefs.erase(std::unique(SymRefs.begin(), SymRefs.end()), SymRefs.end());
-
-    NumRefs += SymRefs.size();
-    auto *Array = Arena.Allocate<Ref>(SymRefs.size());
-    std::uninitialized_copy(SymRefs.begin(), SymRefs.end(), Array);
-    Result.emplace_back(Sym.first, llvm::ArrayRef<Ref>(Array, SymRefs.size()));
-  }
-  return RefSlab(std::move(Result), std::move(Arena), NumRefs);
-}
-
 void SwapIndex::reset(std::unique_ptr<SymbolIndex> Index) {
   // Keep the old index alive, so we don't destroy it under lock (may be slow).
   std::shared_ptr<SymbolIndex> Pin;
Index: clang-tools-extra/trunk/clangd/index/Ref.h
===================================================================
--- clang-tools-extra/trunk/clangd/index/Ref.h
+++ clang-tools-extra/trunk/clangd/index/Ref.h
@@ -0,0 +1,119 @@
+//===--- Ref.h ---------------------------------------------------*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_REF_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_REF_H
+
+#include "SymbolID.h"
+#include "SymbolLocation.h"
+#include "clang/Index/IndexSymbol.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/StringSaver.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstdint>
+#include <utility>
+
+namespace clang {
+namespace clangd {
+
+/// Describes the kind of a cross-reference.
+///
+/// This is a bitfield which can be combined from different kinds.
+enum class RefKind : uint8_t {
+  Unknown = 0,
+  Declaration = static_cast<uint8_t>(index::SymbolRole::Declaration),
+  Definition = static_cast<uint8_t>(index::SymbolRole::Definition),
+  Reference = static_cast<uint8_t>(index::SymbolRole::Reference),
+  All = Declaration | Definition | Reference,
+};
+
+inline RefKind operator|(RefKind L, RefKind R) {
+  return static_cast<RefKind>(static_cast<uint8_t>(L) |
+                              static_cast<uint8_t>(R));
+}
+inline RefKind &operator|=(RefKind &L, RefKind R) { return L = L | R; }
+inline RefKind operator&(RefKind A, RefKind B) {
+  return static_cast<RefKind>(static_cast<uint8_t>(A) &
+                              static_cast<uint8_t>(B));
+}
+
+llvm::raw_ostream &operator<<(llvm::raw_ostream &, RefKind);
+
+/// Represents a symbol occurrence in the source file.
+/// Despite the name, it could be a declaration/definition/reference.
+///
+/// WARNING: Location does not own the underlying data - Copies are shallow.
+struct Ref {
+  /// The source location where the symbol is named.
+  SymbolLocation Location;
+  RefKind Kind = RefKind::Unknown;
+};
+
+inline bool operator<(const Ref &L, const Ref &R) {
+  return std::tie(L.Location, L.Kind) < std::tie(R.Location, R.Kind);
+}
+inline bool operator==(const Ref &L, const Ref &R) {
+  return std::tie(L.Location, L.Kind) == std::tie(R.Location, R.Kind);
+}
+
+llvm::raw_ostream &operator<<(llvm::raw_ostream &, const Ref &);
+
+/// An efficient structure of storing large set of symbol references in memory.
+/// Filenames are deduplicated.
+class RefSlab {
+public:
+  using value_type = std::pair<SymbolID, llvm::ArrayRef<Ref>>;
+  using const_iterator = std::vector<value_type>::const_iterator;
+  using iterator = const_iterator;
+
+  RefSlab() = default;
+  RefSlab(RefSlab &&Slab) = default;
+  RefSlab &operator=(RefSlab &&RHS) = default;
+
+  const_iterator begin() const { return Refs.begin(); }
+  const_iterator end() const { return Refs.end(); }
+  /// Gets the number of symbols.
+  size_t size() const { return Refs.size(); }
+  size_t numRefs() const { return NumRefs; }
+  bool empty() const { return Refs.empty(); }
+
+  size_t bytes() const {
+    return sizeof(*this) + Arena.getTotalMemory() +
+           sizeof(value_type) * Refs.size();
+  }
+
+  /// RefSlab::Builder is a mutable container that can 'freeze' to RefSlab.
+  class Builder {
+  public:
+    Builder() : UniqueStrings(Arena) {}
+    /// Adds a ref to the slab. Deep copy: Strings will be owned by the slab.
+    void insert(const SymbolID &ID, const Ref &S);
+    /// Consumes the builder to finalize the slab.
+    RefSlab build() &&;
+
+  private:
+    llvm::BumpPtrAllocator Arena;
+    llvm::UniqueStringSaver UniqueStrings; // Contents on the arena.
+    llvm::DenseMap<SymbolID, std::vector<Ref>> Refs;
+  };
+
+private:
+  RefSlab(std::vector<value_type> Refs, llvm::BumpPtrAllocator Arena,
+          size_t NumRefs)
+      : Arena(std::move(Arena)), Refs(std::move(Refs)), NumRefs(NumRefs) {}
+
+  llvm::BumpPtrAllocator Arena;
+  std::vector<value_type> Refs;
+  /// Number of all references.
+  size_t NumRefs = 0;
+};
+
+} // namespace clangd
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_REF_H
Index: clang-tools-extra/trunk/clangd/index/Ref.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/index/Ref.cpp
+++ clang-tools-extra/trunk/clangd/index/Ref.cpp
@@ -0,0 +1,62 @@
+//===--- Ref.cpp -------------------------------------------------*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Ref.h"
+
+namespace clang {
+namespace clangd {
+
+llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, RefKind K) {
+  if (K == RefKind::Unknown)
+    return OS << "Unknown";
+  static const std::vector<const char *> Messages = {"Decl", "Def", "Ref"};
+  bool VisitedOnce = false;
+  for (unsigned I = 0; I < Messages.size(); ++I) {
+    if (static_cast<uint8_t>(K) & 1u << I) {
+      if (VisitedOnce)
+        OS << ", ";
+      OS << Messages[I];
+      VisitedOnce = true;
+    }
+  }
+  return OS;
+}
+
+llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Ref &R) {
+  return OS << R.Location << ":" << R.Kind;
+}
+
+void RefSlab::Builder::insert(const SymbolID &ID, const Ref &S) {
+  auto &M = Refs[ID];
+  M.push_back(S);
+  M.back().Location.FileURI =
+      UniqueStrings.save(M.back().Location.FileURI).data();
+}
+
+RefSlab RefSlab::Builder::build() && {
+  // We can reuse the arena, as it only has unique strings and we need them all.
+  // Reallocate refs on the arena to reduce waste and indirections when reading.
+  std::vector<std::pair<SymbolID, llvm::ArrayRef<Ref>>> Result;
+  Result.reserve(Refs.size());
+  size_t NumRefs = 0;
+  for (auto &Sym : Refs) {
+    auto &SymRefs = Sym.second;
+    llvm::sort(SymRefs);
+    // FIXME: do we really need to dedup?
+    SymRefs.erase(std::unique(SymRefs.begin(), SymRefs.end()), SymRefs.end());
+
+    NumRefs += SymRefs.size();
+    auto *Array = Arena.Allocate<Ref>(SymRefs.size());
+    std::uninitialized_copy(SymRefs.begin(), SymRefs.end(), Array);
+    Result.emplace_back(Sym.first, llvm::ArrayRef<Ref>(Array, SymRefs.size()));
+  }
+  return RefSlab(std::move(Result), std::move(Arena), NumRefs);
+}
+
+} // namespace clangd
+} // namespace clang
Index: clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp
+++ clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp
@@ -11,6 +11,7 @@
 #include "CanonicalIncludes.h"
 #include "CodeComplete.h"
 #include "CodeCompletionStrings.h"
+#include "ExpectedTypes.h"
 #include "Logger.h"
 #include "SourceCode.h"
 #include "SymbolLocation.h"
Index: clang-tools-extra/trunk/clangd/indexer/IndexerMain.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/indexer/IndexerMain.cpp
+++ clang-tools-extra/trunk/clangd/indexer/IndexerMain.cpp
@@ -10,10 +10,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "index/Index.h"
 #include "index/IndexAction.h"
 #include "index/Merge.h"
+#include "index/Ref.h"
 #include "index/Serialization.h"
+#include "index/Symbol.h"
 #include "index/SymbolCollector.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "clang/Tooling/Execution.h"