IR, Bitcode: Change bitcode reader to no longer own its memory buffer.

Unique ownership is just one possible ownership pattern for the memory buffer
underlying the bitcode reader. In practice, as this patch shows, ownership can
often reside at a higher level. With the upcoming change to allow multiple
modules in a single bitcode file, it will no longer be appropriate for
modules to generally have unique ownership of their memory buffer.

The C API exposes the ownership relation via the LLVMGetBitcodeModuleInContext
and LLVMGetBitcodeModuleInContext2 functions, so we still need some way for
the module to own the memory buffer. This patch does so by adding an owned
memory buffer field to Module, and using it in a few other places where it
is convenient.

Differential Revision: https://reviews.llvm.org/D26384

llvm-svn: 286214

include/llvm/Bitcode/ReaderWriter.h

@@ -39,12 +39,18 @@ namespace llvm {
 
   /// Read the header of the specified bitcode buffer and prepare for lazy
   /// deserialization of function bodies. If ShouldLazyLoadMetadata is true,
-  /// lazily load metadata as well. If successful, this moves Buffer. On
+  /// lazily load metadata as well.
+  ErrorOr<std::unique_ptr<Module>>
+  getLazyBitcodeModule(MemoryBufferRef Buffer, LLVMContext &Context,
+                       bool ShouldLazyLoadMetadata = false);
+
+  /// Like getLazyBitcodeModule, except that the module takes ownership of
+  /// the memory buffer if successful. If successful, this moves Buffer. On
   /// error, this *does not* move Buffer.
   ErrorOr<std::unique_ptr<Module>>
-  getLazyBitcodeModule(std::unique_ptr<MemoryBuffer> &&Buffer,
-                       LLVMContext &Context,
-                       bool ShouldLazyLoadMetadata = false);
+  getOwningLazyBitcodeModule(std::unique_ptr<MemoryBuffer> &&Buffer,
+                             LLVMContext &Context,
+                             bool ShouldLazyLoadMetadata = false);
 
   /// Read the header of the specified bitcode buffer and extract just the
   /// triple information. If successful, this returns a string. On error, this

include/llvm/IR/Module.h

@@ -33,6 +33,7 @@ template <typename T> class Optional;
 class FunctionType;
 class GVMaterializer;
 class LLVMContext;
+class MemoryBuffer;
 class RandomNumberGenerator;
 class StructType;
 template <class PtrType> class SmallPtrSetImpl;
@@ -158,6 +159,9 @@ private:
   std::string GlobalScopeAsm;     ///< Inline Asm at global scope.
   ValueSymbolTable *ValSymTab;    ///< Symbol table for values
   ComdatSymTabType ComdatSymTab;  ///< Symbol table for COMDATs
+  std::unique_ptr<MemoryBuffer>
+  OwnedMemoryBuffer;              ///< Memory buffer directly owned by this
+                                  ///< module, for legacy clients only.
   std::unique_ptr<GVMaterializer>
   Materializer;                   ///< Used to materialize GlobalValues
   std::string ModuleID;           ///< Human readable identifier for the module
@@ -802,6 +806,9 @@ public:
   /// \brief Returns profile summary metadata
   Metadata *getProfileSummary();
   /// @}
+
+  /// Take ownership of the given memory buffer.
+  void setOwnedMemoryBuffer(std::unique_ptr<MemoryBuffer> MB);
 };
 
 /// \brief Given "llvm.used" or "llvm.compiler.used" as a global name, collect

lib/Bitcode/Reader/BitReader.cpp

@@ -101,7 +101,7 @@ LLVMBool LLVMGetBitcodeModuleInContext(LLVMContextRef ContextRef,
   std::unique_ptr<MemoryBuffer> Owner(unwrap(MemBuf));
 
   ErrorOr<std::unique_ptr<Module>> ModuleOrErr =
-      getLazyBitcodeModule(std::move(Owner), Ctx);
+      getOwningLazyBitcodeModule(std::move(Owner), Ctx);
   Owner.release();
   Ctx.setDiagnosticHandler(OldDiagnosticHandler, OldDiagnosticContext, true);
 
@@ -124,7 +124,7 @@ LLVMBool LLVMGetBitcodeModuleInContext2(LLVMContextRef ContextRef,
   std::unique_ptr<MemoryBuffer> Owner(unwrap(MemBuf));
 
   ErrorOr<std::unique_ptr<Module>> ModuleOrErr =
-      getLazyBitcodeModule(std::move(Owner), Ctx);
+      getOwningLazyBitcodeModule(std::move(Owner), Ctx);
   Owner.release();
 
   if (ModuleOrErr.getError()) {

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -230,9 +230,9 @@ private:
 
 class BitcodeReaderBase {
 protected:
-  BitcodeReaderBase(MemoryBuffer *Buffer) : Buffer(Buffer) {}
+  BitcodeReaderBase(MemoryBufferRef Buffer) : Buffer(Buffer) {}
 
-  std::unique_ptr<MemoryBuffer> Buffer;
+  MemoryBufferRef Buffer;
   BitstreamBlockInfo BlockInfo;
   BitstreamCursor Stream;
 
@@ -244,10 +244,10 @@ protected:
 };
 
 std::error_code BitcodeReaderBase::initStream() {
-  const unsigned char *BufPtr = (const unsigned char*)Buffer->getBufferStart();
-  const unsigned char *BufEnd = BufPtr+Buffer->getBufferSize();
+  const unsigned char *BufPtr = (const unsigned char*)Buffer.getBufferStart();
+  const unsigned char *BufEnd = BufPtr+Buffer.getBufferSize();
 
-  if (Buffer->getBufferSize() & 3)
+  if (Buffer.getBufferSize() & 3)
     return error("Invalid bitcode signature");
 
   // If we have a wrapper header, parse it and ignore the non-bc file contents.
@@ -360,15 +360,10 @@ public:
   std::error_code error(BitcodeError E, const Twine &Message);
   std::error_code error(const Twine &Message) override;
 
-  BitcodeReader(MemoryBuffer *Buffer, LLVMContext &Context);
-  ~BitcodeReader() override { freeState(); }
+  BitcodeReader(MemoryBufferRef Buffer, LLVMContext &Context);
 
   std::error_code materializeForwardReferencedFunctions();
 
-  void freeState();
-
-  void releaseBuffer();
-
   std::error_code materialize(GlobalValue *GV) override;
   std::error_code materializeModule() override;
   std::vector<StructType *> getIdentifiedStructTypes() const override;
@@ -585,13 +580,8 @@ public:
   std::error_code error(const Twine &Message);
 
   ModuleSummaryIndexBitcodeReader(
-      MemoryBuffer *Buffer, DiagnosticHandlerFunction DiagnosticHandler,
+      MemoryBufferRef Buffer, DiagnosticHandlerFunction DiagnosticHandler,
       bool CheckGlobalValSummaryPresenceOnly = false);
-  ~ModuleSummaryIndexBitcodeReader() { freeState(); }
-
-  void freeState();
-
-  void releaseBuffer();
 
   /// Check if the parser has encountered a summary section.
   bool foundGlobalValSummary() { return SeenGlobalValSummary; }
@@ -661,7 +651,7 @@ std::error_code BitcodeReader::error(const Twine &Message) {
                  Message);
 }
 
-BitcodeReader::BitcodeReader(MemoryBuffer *Buffer, LLVMContext &Context)
+BitcodeReader::BitcodeReader(MemoryBufferRef Buffer, LLVMContext &Context)
     : BitcodeReaderBase(Buffer), Context(Context), ValueList(Context),
       MetadataList(Context) {}
 
@@ -698,24 +688,6 @@ std::error_code BitcodeReader::materializeForwardReferencedFunctions() {
   return std::error_code();
 }
 
-void BitcodeReader::freeState() {
-  Buffer = nullptr;
-  std::vector<Type*>().swap(TypeList);
-  ValueList.clear();
-  MetadataList.clear();
-  std::vector<Comdat *>().swap(ComdatList);
-
-  std::vector<AttributeSet>().swap(MAttributes);
-  std::vector<BasicBlock*>().swap(FunctionBBs);
-  std::vector<Function*>().swap(FunctionsWithBodies);
-  DeferredFunctionInfo.clear();
-  DeferredMetadataInfo.clear();
-  MDKindMap.clear();
-
-  assert(BasicBlockFwdRefs.empty() && "Unresolved blockaddress fwd references");
-  BasicBlockFwdRefQueue.clear();
-}
-
 //===----------------------------------------------------------------------===//
 //  Helper functions to implement forward reference resolution, etc.
 //===----------------------------------------------------------------------===//
@@ -5887,8 +5859,6 @@ std::error_code BitcodeReader::findFunctionInStream(
 // GVMaterializer implementation
 //===----------------------------------------------------------------------===//
 
-void BitcodeReader::releaseBuffer() { Buffer.release(); }
-
 std::error_code BitcodeReader::materialize(GlobalValue *GV) {
   Function *F = dyn_cast<Function>(GV);
   // If it's not a function or is already material, ignore the request.
@@ -6006,16 +5976,12 @@ std::error_code ModuleSummaryIndexBitcodeReader::error(const Twine &Message) {
 }
 
 ModuleSummaryIndexBitcodeReader::ModuleSummaryIndexBitcodeReader(
-    MemoryBuffer *Buffer, DiagnosticHandlerFunction DiagnosticHandler,
+    MemoryBufferRef Buffer, DiagnosticHandlerFunction DiagnosticHandler,
     bool CheckGlobalValSummaryPresenceOnly)
     : BitcodeReaderBase(Buffer),
       DiagnosticHandler(std::move(DiagnosticHandler)),
       CheckGlobalValSummaryPresenceOnly(CheckGlobalValSummaryPresenceOnly) {}
 
-void ModuleSummaryIndexBitcodeReader::freeState() { Buffer = nullptr; }
-
-void ModuleSummaryIndexBitcodeReader::releaseBuffer() { Buffer.release(); }
-
 std::pair<GlobalValue::GUID, GlobalValue::GUID>
 ModuleSummaryIndexBitcodeReader::getGUIDFromValueId(unsigned ValueId) {
   auto VGI = ValueIdToCallGraphGUIDMap.find(ValueId);
@@ -6219,7 +6185,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseModule() {
             break;
           if (TheIndex->modulePaths().empty())
             // We always seed the index with the module.
-            TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0);
+            TheIndex->addModulePath(Buffer.getBufferIdentifier(), 0);
           if (TheIndex->modulePaths().size() != 1)
             return error("Don't expect multiple modules defined?");
           auto &Hash = TheIndex->modulePaths().begin()->second.second;
@@ -6359,7 +6325,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
       // module path string table entry with an empty (0) ID to take
       // ownership.
       FS->setModulePath(
-          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0)->first());
+          TheIndex->addModulePath(Buffer.getBufferIdentifier(), 0)->first());
       static int RefListStartIndex = 4;
       int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
       assert(Record.size() >= RefListStartIndex + NumRefs &&
@@ -6398,7 +6364,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
       // module path string table entry with an empty (0) ID to take
       // ownership.
       AS->setModulePath(
-          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0)->first());
+          TheIndex->addModulePath(Buffer.getBufferIdentifier(), 0)->first());
 
       GlobalValue::GUID AliaseeGUID = getGUIDFromValueId(AliaseeID).first;
       auto *AliaseeSummary = TheIndex->getGlobalValueSummary(AliaseeGUID);
@@ -6419,7 +6385,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
       std::unique_ptr<GlobalVarSummary> FS =
           llvm::make_unique<GlobalVarSummary>(Flags);
       FS->setModulePath(
-          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0)->first());
+          TheIndex->addModulePath(Buffer.getBufferIdentifier(), 0)->first());
       for (unsigned I = 2, E = Record.size(); I != E; ++I) {
         unsigned RefValueId = Record[I];
         GlobalValue::GUID RefGUID = getGUIDFromValueId(RefValueId).first;
@@ -6677,33 +6643,6 @@ const std::error_category &llvm::BitcodeErrorCategory() {
 // External interface
 //===----------------------------------------------------------------------===//
 
-static ErrorOr<std::unique_ptr<Module>>
-getBitcodeModuleImpl(StringRef Name, BitcodeReader *R, LLVMContext &Context,
-                     bool MaterializeAll, bool ShouldLazyLoadMetadata) {
-  std::unique_ptr<Module> M = llvm::make_unique<Module>(Name, Context);
-  M->setMaterializer(R);
-
-  auto cleanupOnError = [&](std::error_code EC) {
-    R->releaseBuffer(); // Never take ownership on error.
-    return EC;
-  };
-
-  // Delay parsing Metadata if ShouldLazyLoadMetadata is true.
-  if (std::error_code EC = R->parseBitcodeInto(M.get(), ShouldLazyLoadMetadata))
-    return cleanupOnError(EC);
-
-  if (MaterializeAll) {
-    // Read in the entire module, and destroy the BitcodeReader.
-    if (std::error_code EC = M->materializeAll())
-      return cleanupOnError(EC);
-  } else {
-    // Resolve forward references from blockaddresses.
-    if (std::error_code EC = R->materializeForwardReferencedFunctions())
-      return cleanupOnError(EC);
-  }
-  return std::move(M);
-}
-
 /// \brief Get a lazy one-at-time loading module from bitcode.
 ///
 /// This isn't always used in a lazy context.  In particular, it's also used by
@@ -6713,41 +6652,59 @@ getBitcodeModuleImpl(StringRef Name, BitcodeReader *R, LLVMContext &Context,
 /// \param[in] MaterializeAll Set to \c true if we should materialize
 /// everything.
 static ErrorOr<std::unique_ptr<Module>>
-getLazyBitcodeModuleImpl(std::unique_ptr<MemoryBuffer> &&Buffer,
-                         LLVMContext &Context, bool MaterializeAll,
+getLazyBitcodeModuleImpl(MemoryBufferRef Buffer, LLVMContext &Context,
+                         bool MaterializeAll,
                          bool ShouldLazyLoadMetadata = false) {
-  BitcodeReader *R = new BitcodeReader(Buffer.get(), Context);
+  BitcodeReader *R = new BitcodeReader(Buffer, Context);
 
-  ErrorOr<std::unique_ptr<Module>> Ret =
-      getBitcodeModuleImpl(Buffer->getBufferIdentifier(), R, Context,
-                           MaterializeAll, ShouldLazyLoadMetadata);
-  if (!Ret)
-    return Ret;
+  std::unique_ptr<Module> M =
+      llvm::make_unique<Module>(Buffer.getBufferIdentifier(), Context);
+  M->setMaterializer(R);
 
-  Buffer.release(); // The BitcodeReader owns it now.
-  return Ret;
+  // Delay parsing Metadata if ShouldLazyLoadMetadata is true.
+  if (std::error_code EC = R->parseBitcodeInto(M.get(), ShouldLazyLoadMetadata))
+    return EC;
+
+  if (MaterializeAll) {
+    // Read in the entire module, and destroy the BitcodeReader.
+    if (std::error_code EC = M->materializeAll())
+      return EC;
+  } else {
+    // Resolve forward references from blockaddresses.
+    if (std::error_code EC = R->materializeForwardReferencedFunctions())
+      return EC;
+  }
+  return std::move(M);
 }
 
 ErrorOr<std::unique_ptr<Module>>
-llvm::getLazyBitcodeModule(std::unique_ptr<MemoryBuffer> &&Buffer,
+llvm::getLazyBitcodeModule(MemoryBufferRef Buffer,
                            LLVMContext &Context, bool ShouldLazyLoadMetadata) {
-  return getLazyBitcodeModuleImpl(std::move(Buffer), Context, false,
+  return getLazyBitcodeModuleImpl(Buffer, Context, false,
                                   ShouldLazyLoadMetadata);
 }
 
+ErrorOr<std::unique_ptr<Module>>
+llvm::getOwningLazyBitcodeModule(std::unique_ptr<MemoryBuffer> &&Buffer,
+                                 LLVMContext &Context,
+                                 bool ShouldLazyLoadMetadata) {
+  auto MOrErr = getLazyBitcodeModule(*Buffer, Context, ShouldLazyLoadMetadata);
+  if (MOrErr)
+    (*MOrErr)->setOwnedMemoryBuffer(std::move(Buffer));
+  return MOrErr;
+}
+
 ErrorOr<std::unique_ptr<Module>> llvm::parseBitcodeFile(MemoryBufferRef Buffer,
                                                         LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
-  return getLazyBitcodeModuleImpl(std::move(Buf), Context, true);
+  return getLazyBitcodeModuleImpl(Buffer, Context, true);
   // TODO: Restore the use-lists to the in-memory state when the bitcode was
   // written.  We must defer until the Module has been fully materialized.
 }
 
 std::string llvm::getBitcodeTargetTriple(MemoryBufferRef Buffer,
                                          LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
-  auto R = llvm::make_unique<BitcodeReader>(Buf.release(), Context);
-  ErrorOr<std::string> Triple = R->parseTriple();
+  BitcodeReader R(Buffer, Context);
+  ErrorOr<std::string> Triple = R.parseTriple();
   if (Triple.getError())
     return "";
   return Triple.get();
@@ -6755,9 +6712,8 @@ std::string llvm::getBitcodeTargetTriple(MemoryBufferRef Buffer,
 
 bool llvm::isBitcodeContainingObjCCategory(MemoryBufferRef Buffer,
                                            LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
-  auto R = llvm::make_unique<BitcodeReader>(Buf.release(), Context);
-  ErrorOr<bool> hasObjCCategory = R->hasObjCCategory();
+  BitcodeReader R(Buffer, Context);
+  ErrorOr<bool> hasObjCCategory = R.hasObjCCategory();
   if (hasObjCCategory.getError())
     return false;
   return hasObjCCategory.get();
@@ -6765,8 +6721,7 @@ bool llvm::isBitcodeContainingObjCCategory(MemoryBufferRef Buffer,
 
 std::string llvm::getBitcodeProducerString(MemoryBufferRef Buffer,
                                            LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
-  BitcodeReader R(Buf.release(), Context);
+  BitcodeReader R(Buffer, Context);
   ErrorOr<std::string> ProducerString = R.parseIdentificationBlock();
   if (ProducerString.getError())
     return "";
@@ -6777,20 +6732,13 @@ std::string llvm::getBitcodeProducerString(MemoryBufferRef Buffer,
 ErrorOr<std::unique_ptr<ModuleSummaryIndex>> llvm::getModuleSummaryIndex(
     MemoryBufferRef Buffer,
     const DiagnosticHandlerFunction &DiagnosticHandler) {
-  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
-  ModuleSummaryIndexBitcodeReader R(Buf.get(), DiagnosticHandler);
+  ModuleSummaryIndexBitcodeReader R(Buffer, DiagnosticHandler);
 
   auto Index = llvm::make_unique<ModuleSummaryIndex>();
 
-  auto cleanupOnError = [&](std::error_code EC) {
-    R.releaseBuffer(); // Never take ownership on error.
-    return EC;
-  };
-
   if (std::error_code EC = R.parseSummaryIndexInto(Index.get()))
-    return cleanupOnError(EC);
+    return EC;
 
-  Buf.release(); // The ModuleSummaryIndexBitcodeReader owns it now.
   return std::move(Index);
 }
 
@@ -6798,17 +6746,10 @@ ErrorOr<std::unique_ptr<ModuleSummaryIndex>> llvm::getModuleSummaryIndex(
 bool llvm::hasGlobalValueSummary(
     MemoryBufferRef Buffer,
     const DiagnosticHandlerFunction &DiagnosticHandler) {
-  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
-  ModuleSummaryIndexBitcodeReader R(Buf.get(), DiagnosticHandler, true);
+  ModuleSummaryIndexBitcodeReader R(Buffer, DiagnosticHandler, true);
 
-  auto cleanupOnError = [&](std::error_code EC) {
-    R.releaseBuffer(); // Never take ownership on error.
+  if (R.parseSummaryIndexInto(nullptr))
     return false;
-  };
 
-  if (std::error_code EC = R.parseSummaryIndexInto(nullptr))
-    return cleanupOnError(EC);
-
-  Buf.release(); // The ModuleSummaryIndexBitcodeReader owns it now.
   return R.foundGlobalValSummary();
 }

lib/IR/Module.cpp

@@ -25,6 +25,7 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/TypeFinder.h"
 #include "llvm/Support/Dwarf.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/RandomNumberGenerator.h"
 #include <algorithm>
@@ -519,6 +520,10 @@ Metadata *Module::getProfileSummary() {
   return getModuleFlag("ProfileSummary");
 }
 
+void Module::setOwnedMemoryBuffer(std::unique_ptr<MemoryBuffer> MB) {
+  OwnedMemoryBuffer = std::move(MB);
+}
+
 GlobalVariable *llvm::collectUsedGlobalVariables(
     const Module &M, SmallPtrSetImpl<GlobalValue *> &Set, bool CompilerUsed) {
   const char *Name = CompilerUsed ? "llvm.compiler.used" : "llvm.used";

lib/IRReader/IRReader.cpp

@@ -34,7 +34,7 @@ getLazyIRModule(std::unique_ptr<MemoryBuffer> Buffer, SMDiagnostic &Err,
                 LLVMContext &Context, bool ShouldLazyLoadMetadata) {
   if (isBitcode((const unsigned char *)Buffer->getBufferStart(),
                 (const unsigned char *)Buffer->getBufferEnd())) {
-    ErrorOr<std::unique_ptr<Module>> ModuleOrErr = getLazyBitcodeModule(
+    ErrorOr<std::unique_ptr<Module>> ModuleOrErr = getOwningLazyBitcodeModule(
         std::move(Buffer), Context, ShouldLazyLoadMetadata);
     if (std::error_code EC = ModuleOrErr.getError()) {
       Err = SMDiagnostic(Buffer->getBufferIdentifier(), SourceMgr::DK_Error,

lib/LTO/LTO.cpp

@@ -105,9 +105,8 @@ llvm::loadModuleFromBuffer(const MemoryBufferRef &Buffer, LLVMContext &Context,
   SMDiagnostic Err;
   ErrorOr<std::unique_ptr<Module>> ModuleOrErr(nullptr);
   if (Lazy) {
-    ModuleOrErr =
-        getLazyBitcodeModule(MemoryBuffer::getMemBuffer(Buffer, false), Context,
-                             /* ShouldLazyLoadMetadata */ Lazy);
+    ModuleOrErr = getLazyBitcodeModule(Buffer, Context,
+                                       /* ShouldLazyLoadMetadata */ Lazy);
   } else {
     ModuleOrErr = parseBitcodeFile(Buffer, Context);
   }

lib/LTO/LTOBackend.cpp

@@ -352,8 +352,7 @@ Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
   auto ModuleLoader = [&](StringRef Identifier) {
     assert(Mod.getContext().isODRUniquingDebugTypes() &&
            "ODR Type uniquing should be enabled on the context");
-    return std::move(getLazyBitcodeModule(MemoryBuffer::getMemBuffer(
-                                              ModuleMap[Identifier], false),
+    return std::move(getLazyBitcodeModule(ModuleMap[Identifier],
                                           Mod.getContext(),
                                           /*ShouldLazyLoadMetadata=*/true)
                          .get());

lib/LTO/LTOModule.cpp

@@ -185,10 +185,8 @@ parseBitcodeFileImpl(MemoryBufferRef Buffer, LLVMContext &Context,
   }
 
   // Parse lazily.
-  std::unique_ptr<MemoryBuffer> LightweightBuf =
-      MemoryBuffer::getMemBuffer(*MBOrErr, false);
-  ErrorOr<std::unique_ptr<Module>> M = getLazyBitcodeModule(
-      std::move(LightweightBuf), Context, true /*ShouldLazyLoadMetadata*/);
+  ErrorOr<std::unique_ptr<Module>> M =
+      getLazyBitcodeModule(*MBOrErr, Context, true /*ShouldLazyLoadMetadata*/);
   if (std::error_code EC = M.getError())
     return EC;
   return std::move(*M);

lib/Object/IRObjectFile.cpp

@@ -317,11 +317,8 @@ llvm::object::IRObjectFile::create(MemoryBufferRef Object,
   if (!BCOrErr)
     return BCOrErr.getError();
 
-  std::unique_ptr<MemoryBuffer> Buff =
-      MemoryBuffer::getMemBuffer(BCOrErr.get(), false);
-
   ErrorOr<std::unique_ptr<Module>> MOrErr =
-      getLazyBitcodeModule(std::move(Buff), Context,
+      getLazyBitcodeModule(*BCOrErr, Context,
                            /*ShouldLazyLoadMetadata*/ true);
   if (std::error_code EC = MOrErr.getError())
     return EC;

tools/llvm-dis/llvm-dis.cpp

@@ -143,8 +143,8 @@ static Expected<std::unique_ptr<Module>> openInputFile(LLVMContext &Context) {
   if (!MBOrErr)
     return errorCodeToError(MBOrErr.getError());
   ErrorOr<std::unique_ptr<Module>> MOrErr =
-      getLazyBitcodeModule(std::move(*MBOrErr), Context,
-                           /*ShouldLazyLoadMetadata=*/true);
+      getOwningLazyBitcodeModule(std::move(*MBOrErr), Context,
+                                 /*ShouldLazyLoadMetadata=*/true);
   if (!MOrErr)
     return errorCodeToError(MOrErr.getError());
   if (MaterializeMetadata)

unittests/Bitcode/BitReaderTest.cpp

@@ -53,10 +53,8 @@ static std::unique_ptr<Module> getLazyModuleFromAssembly(LLVMContext &Context,
                                                          SmallString<1024> &Mem,
                                                          const char *Assembly) {
   writeModuleToBuffer(parseAssembly(Context, Assembly), Mem);
-  std::unique_ptr<MemoryBuffer> Buffer =
-      MemoryBuffer::getMemBuffer(Mem.str(), "test", false);
   ErrorOr<std::unique_ptr<Module>> ModuleOrErr =
-      getLazyBitcodeModule(std::move(Buffer), Context);
+      getLazyBitcodeModule(MemoryBufferRef(Mem.str(), "test"), Context);
   return std::move(ModuleOrErr.get());
 }