2 files changed, 10 insertions, 27 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 952992a9e8b..ac5c7ca3be3 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -18,7 +18,6 @@
 #include "clang/AST/StmtVisitor.h"
 #include "clang/AST/TypeOrdering.h"
 #include "clang/Basic/Diagnostic.h"
-#include "clang/Basic/MemoryBufferCache.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/TargetOptions.h"
 #include "clang/Basic/VirtualFileSystem.h"
@@ -186,8 +185,7 @@ struct ASTUnit::ASTWriterData {
   llvm::BitstreamWriter Stream;
   ASTWriter Writer;
 
-  ASTWriterData(MemoryBufferCache &PCMCache)
-      : Stream(Buffer), Writer(Stream, Buffer, PCMCache, {}) {}
+  ASTWriterData() : Stream(Buffer), Writer(Stream, Buffer, {}) {}
 };
 
 void ASTUnit::clearFileLevelDecls() {
@@ -683,7 +681,6 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
   AST->SourceMgr = new SourceManager(AST->getDiagnostics(),
                                      AST->getFileManager(),
                                      UserFilesAreVolatile);
-  AST->PCMCache = new MemoryBufferCache;
   AST->HSOpts = std::make_shared<HeaderSearchOptions>();
   AST->HSOpts->ModuleFormat = PCHContainerRdr.getFormat();
   AST->HeaderInfo.reset(new HeaderSearch(AST->HSOpts,
@@ -704,7 +701,7 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
 
   AST->PP = std::make_shared<Preprocessor>(
       std::move(PPOpts), AST->getDiagnostics(), AST->ASTFileLangOpts,
-      AST->getSourceManager(), *AST->PCMCache, HeaderInfo, *AST,
+      AST->getSourceManager(), HeaderInfo, *AST,
       /*IILookup=*/nullptr,
       /*OwnsHeaderSearch=*/false);
   Preprocessor &PP = *AST->PP;
@@ -1730,7 +1727,6 @@ ASTUnit::create(std::shared_ptr<CompilerInvocation> CI,
   AST->UserFilesAreVolatile = UserFilesAreVolatile;
   AST->SourceMgr = new SourceManager(AST->getDiagnostics(), *AST->FileMgr,
                                      UserFilesAreVolatile);
-  AST->PCMCache = new MemoryBufferCache;
 
   return AST;
 }
@@ -2001,7 +1997,6 @@ ASTUnit *ASTUnit::LoadFromCommandLine(
   if (!VFS)
     return nullptr;
   AST->FileMgr = new FileManager(AST->FileSystemOpts, VFS);
-  AST->PCMCache = new MemoryBufferCache;
   AST->OnlyLocalDecls = OnlyLocalDecls;
   AST->CaptureDiagnostics = CaptureDiagnostics;
   AST->TUKind = TUKind;
@@ -2013,7 +2008,7 @@ ASTUnit *ASTUnit::LoadFromCommandLine(
   AST->StoredDiagnostics.swap(StoredDiagnostics);
   AST->Invocation = CI;
   if (ForSerialization)
-    AST->WriterData.reset(new ASTWriterData(*AST->PCMCache));
+    AST->WriterData.reset(new ASTWriterData());
   // Zero out now to ease cleanup during crash recovery.
   CI = nullptr;
   Diags = nullptr;
@@ -2528,8 +2523,7 @@ bool ASTUnit::serialize(raw_ostream &OS) {
 
   SmallString<128> Buffer;
   llvm::BitstreamWriter Stream(Buffer);
-  MemoryBufferCache PCMCache;
-  ASTWriter Writer(Stream, Buffer, PCMCache, {});
+  ASTWriter Writer(Stream, Buffer, {});
   return serializeUnit(Writer, Buffer, getSema(), hasErrors, OS);
 }
 
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index f660429e49d..bf15460824f 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -13,7 +13,6 @@
 #include "clang/AST/Decl.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/FileManager.h"
-#include "clang/Basic/MemoryBufferCache.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/Version.h"
@@ -56,15 +55,9 @@ using namespace clang;
 
 CompilerInstance::CompilerInstance(
     std::shared_ptr<PCHContainerOperations> PCHContainerOps,
-    MemoryBufferCache *SharedPCMCache)
-    : ModuleLoader(/* BuildingModule = */ SharedPCMCache),
-      Invocation(new CompilerInvocation()),
-      PCMCache(SharedPCMCache ? SharedPCMCache : new MemoryBufferCache),
-      ThePCHContainerOperations(std::move(PCHContainerOps)) {
-  // Don't allow this to invalidate buffers in use by others.
-  if (SharedPCMCache)
-    getPCMCache().finalizeCurrentBuffers();
-}
+    bool BuildingModule)
+    : ModuleLoader(BuildingModule), Invocation(new CompilerInvocation()),
+      ThePCHContainerOperations(std::move(PCHContainerOps)) {}
 
 CompilerInstance::~CompilerInstance() {
   assert(OutputFiles.empty() && "Still output files in flight?");
@@ -135,8 +128,6 @@ IntrusiveRefCntPtr<ASTReader> CompilerInstance::getModuleManager() const {
   return ModuleManager;
 }
 void CompilerInstance::setModuleManager(IntrusiveRefCntPtr<ASTReader> Reader) {
-  assert(PCMCache.get() == &Reader->getModuleManager().getPCMCache() &&
-         "Expected ASTReader to use the same PCM cache");
   ModuleManager = std::move(Reader);
 }
 
@@ -379,7 +370,7 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
                        getDiagnostics(), getLangOpts(), &getTarget());
   PP = std::make_shared<Preprocessor>(
       Invocation->getPreprocessorOptsPtr(), getDiagnostics(), getLangOpts(),
-      getSourceManager(), getPCMCache(), *HeaderInfo, *this, PTHMgr,
+      getSourceManager(), *HeaderInfo, *this, PTHMgr,
       /*OwnsHeaderSearch=*/true, TUKind);
   PP->Initialize(getTarget(), getAuxTarget());
 
@@ -1082,11 +1073,9 @@ static bool compileModuleImpl(CompilerInstance &ImportingInstance,
          Invocation->getModuleHash() && "Module hash mismatch!");
   
   // Construct a compiler instance that will be used to actually create the
-  // module.  Since we're sharing a PCMCache,
-  // CompilerInstance::CompilerInstance is responsible for finalizing the
-  // buffers to prevent use-after-frees.
+  // module.
   CompilerInstance Instance(ImportingInstance.getPCHContainerOperations(),
-                            &ImportingInstance.getPreprocessor().getPCMCache());
+                            /*BuildingModule=*/true);
   auto &Inv = *Invocation;
   Instance.setInvocation(std::move(Invocation));