--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/lib/Serialization/InMemoryModuleCache.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,67 @@
+//===- InMemoryModuleCache.cpp - Cache for loaded memory buffers ----------===//
+//
+// 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 "clang/Serialization/InMemoryModuleCache.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace clang;
+
+llvm::MemoryBuffer &
+InMemoryModuleCache::addPCM(llvm::StringRef Filename,
+                            std::unique_ptr<llvm::MemoryBuffer> Buffer) {
+  auto Insertion = PCMs.insert(std::make_pair(Filename, std::move(Buffer)));
+  assert(Insertion.second && "Already has a PCM");
+  return *Insertion.first->second.Buffer;
+}
+
+llvm::MemoryBuffer &
+InMemoryModuleCache::addFinalPCM(llvm::StringRef Filename,
+                                 std::unique_ptr<llvm::MemoryBuffer> Buffer) {
+  auto &PCM = PCMs[Filename];
+  assert(!PCM.IsFinal && "Trying to override finalized PCM?");
+  assert(!PCM.Buffer && "Already has a non-final PCM");
+  PCM.Buffer = std::move(Buffer);
+  PCM.IsFinal = true;
+  return *PCM.Buffer;
+}
+
+llvm::MemoryBuffer *
+InMemoryModuleCache::lookupPCM(llvm::StringRef Filename) const {
+  auto I = PCMs.find(Filename);
+  if (I == PCMs.end())
+    return nullptr;
+  return I->second.Buffer.get();
+}
+
+bool InMemoryModuleCache::isPCMFinal(llvm::StringRef Filename) const {
+  auto I = PCMs.find(Filename);
+  if (I == PCMs.end())
+    return false;
+  return I->second.IsFinal;
+}
+
+bool InMemoryModuleCache::tryToRemovePCM(llvm::StringRef Filename) {
+  auto I = PCMs.find(Filename);
+  assert(I != PCMs.end() && "PCM to remove is unknown...");
+
+  auto &PCM = I->second;
+  if (PCM.IsFinal)
+    return true;
+
+  PCMs.erase(I);
+  return false;
+}
+
+void InMemoryModuleCache::finalizePCM(llvm::StringRef Filename) {
+  auto I = PCMs.find(Filename);
+  assert(I != PCMs.end() && "PCM to finalize is unknown...");
+
+  auto &PCM = I->second;
+  assert(PCM.Buffer && "Trying to finalize a dropped PCM...");
+  PCM.IsFinal = true;
+}