Pass a MemoryBufferRef when we can avoid taking ownership.

The attached patch simplifies a few interfaces that don't need to take
ownership of a buffer.

For example, both parseAssembly and parseBitcodeFile will parse the
entire buffer before returning. There is no need to take ownership.

Using a MemoryBufferRef makes it obvious in the type signature that
there is no ownership transfer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216488 91177308-0d34-0410-b5e6-96231b3b80d8

16 files changed, 58 insertions, 71 deletions

diff --git a/include/llvm/AsmParser/Parser.h b/include/llvm/AsmParser/Parser.h
index c362a177439..7ef78d73da1 100644
--- a/include/llvm/AsmParser/Parser.h
+++ b/include/llvm/AsmParser/Parser.h
@@ -14,13 +14,11 @@
 #ifndef LLVM_ASMPARSER_PARSER_H
 #define LLVM_ASMPARSER_PARSER_H
 
-#include "llvm/ADT/StringRef.h"
-#include <memory>
+#include "llvm/Support/MemoryBuffer.h"
 
 namespace llvm {
 
 class Module;
-class MemoryBuffer;
 class SMDiagnostic;
 class LLVMContext;
 
@@ -55,8 +53,8 @@ std::unique_ptr<Module> parseAssemblyString(StringRef AsmString,
 /// @param F The MemoryBuffer containing assembly
 /// @param Err Error result info.
 /// @param Context Context in which to allocate globals info.
-std::unique_ptr<Module> parseAssembly(std::unique_ptr<MemoryBuffer> F,
-                                      SMDiagnostic &Err, LLVMContext &Context);
+std::unique_ptr<Module> parseAssembly(MemoryBufferRef F, SMDiagnostic &Err,
+                                      LLVMContext &Context);
 
 /// This function is the low-level interface to the LLVM Assembly Parser.
 /// This is kept as an independent function instead of being inlined into
@@ -67,8 +65,7 @@ std::unique_ptr<Module> parseAssembly(std::unique_ptr<MemoryBuffer> F,
 /// @param M The module to add data to.
 /// @param Err Error result info.
 /// @return true on error.
-bool parseAssemblyInto(std::unique_ptr<MemoryBuffer> F, Module &M,
-                       SMDiagnostic &Err);
+bool parseAssemblyInto(MemoryBufferRef F, Module &M, SMDiagnostic &Err);
 
 } // End llvm namespace
 
diff --git a/include/llvm/Bitcode/ReaderWriter.h b/include/llvm/Bitcode/ReaderWriter.h
index 6fb77565979..c1eca8d9eaf 100644
--- a/include/llvm/Bitcode/ReaderWriter.h
+++ b/include/llvm/Bitcode/ReaderWriter.h
@@ -15,11 +15,11 @@
 #define LLVM_BITCODE_READERWRITER_H
 
 #include "llvm/Support/ErrorOr.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include <string>
 
 namespace llvm {
   class BitstreamWriter;
-  class MemoryBuffer;
   class DataStreamer;
   class LLVMContext;
   class Module;
@@ -42,14 +42,13 @@ namespace llvm {
                                    std::string *ErrMsg = nullptr);
 
   /// Read the header of the specified bitcode buffer and extract just the
-  /// triple information. If successful, this returns a string and *does not*
-  /// take ownership of 'buffer'. On error, this returns "".
-  std::string getBitcodeTargetTriple(MemoryBuffer *Buffer,
+  /// triple information. If successful, this returns a string. On error, this
+  /// returns "".
+  std::string getBitcodeTargetTriple(MemoryBufferRef Buffer,
                                      LLVMContext &Context);
 
   /// Read the specified bitcode file, returning the module.
-  /// This method *never* takes ownership of Buffer.
-  ErrorOr<Module *> parseBitcodeFile(MemoryBuffer *Buffer,
+  ErrorOr<Module *> parseBitcodeFile(MemoryBufferRef Buffer,
                                      LLVMContext &Context);
 
   /// WriteBitcodeToFile - Write the specified module to the specified
diff --git a/include/llvm/IR/GVMaterializer.h b/include/llvm/IR/GVMaterializer.h
index a1216a17428..4afdbb05f85 100644
--- a/include/llvm/IR/GVMaterializer.h
+++ b/include/llvm/IR/GVMaterializer.h
@@ -54,8 +54,6 @@ public:
   /// Make sure the entire Module has been completely read.
   ///
   virtual std::error_code MaterializeModule(Module *M) = 0;
-
-  virtual void releaseBuffer() = 0;
 };
 
 } // End llvm namespace
diff --git a/include/llvm/IR/Module.h b/include/llvm/IR/Module.h
index 1fdbf5d878b..51d43af6365 100644
--- a/include/llvm/IR/Module.h
+++ b/include/llvm/IR/Module.h
@@ -483,7 +483,7 @@ public:
   /// Make sure all GlobalValues in this Module are fully read and clear the
   /// Materializer. If the module is corrupt, this DOES NOT clear the old
   /// Materializer.
-  std::error_code materializeAllPermanently(bool ReleaseBuffer = false);
+  std::error_code materializeAllPermanently();
 
 /// @}
 /// @name Direct access to the globals list, functions list, and symbol table
diff --git a/include/llvm/IRReader/IRReader.h b/include/llvm/IRReader/IRReader.h
index c3ccffefa84..2d9ace0b62a 100644
--- a/include/llvm/IRReader/IRReader.h
+++ b/include/llvm/IRReader/IRReader.h
@@ -15,14 +15,12 @@
 #ifndef LLVM_IRREADER_IRREADER_H
 #define LLVM_IRREADER_IRREADER_H
 
-#include "llvm/ADT/StringRef.h"
-#include <memory>
+#include "llvm/Support/MemoryBuffer.h"
 #include <string>
 
 namespace llvm {
 
 class Module;
-class MemoryBuffer;
 class SMDiagnostic;
 class LLVMContext;
 
@@ -36,8 +34,8 @@ std::unique_ptr<Module> getLazyIRFileModule(StringRef Filename,
 
 /// If the given MemoryBuffer holds a bitcode image, return a Module
 /// for it.  Otherwise, attempt to parse it as LLVM Assembly and return
-/// a Module for it. This function *never* takes ownership of Buffer.
-std::unique_ptr<Module> parseIR(MemoryBuffer *Buffer, SMDiagnostic &Err,
+/// a Module for it.
+std::unique_ptr<Module> parseIR(MemoryBufferRef Buffer, SMDiagnostic &Err,
                                 LLVMContext &Context);
 
 /// If the given file holds a bitcode image, return a Module for it.
diff --git a/include/llvm/Support/MemoryBuffer.h b/include/llvm/Support/MemoryBuffer.h
index acea48a8bf8..827d896686d 100644
--- a/include/llvm/Support/MemoryBuffer.h
+++ b/include/llvm/Support/MemoryBuffer.h
@@ -102,6 +102,9 @@ public:
                                     StringRef BufferName = "",
                                     bool RequiresNullTerminator = true);
 
+  static std::unique_ptr<MemoryBuffer>
+  getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true);
+
   /// Open the specified memory range as a MemoryBuffer, copying the contents
   /// and taking ownership of it. InputData does not have to be null terminated.
   static MemoryBuffer *getMemBufferCopy(StringRef InputData,
diff --git a/lib/AsmParser/Parser.cpp b/lib/AsmParser/Parser.cpp
index d2384bd978d..08159075ff6 100644
--- a/lib/AsmParser/Parser.cpp
+++ b/lib/AsmParser/Parser.cpp
@@ -21,22 +21,21 @@
 #include <system_error>
 using namespace llvm;
 
-bool llvm::parseAssemblyInto(std::unique_ptr<MemoryBuffer> F, Module &M,
-                             SMDiagnostic &Err) {
+bool llvm::parseAssemblyInto(MemoryBufferRef F, Module &M, SMDiagnostic &Err) {
   SourceMgr SM;
-  StringRef Buf = F->getBuffer();
-  SM.AddNewSourceBuffer(std::move(F), SMLoc());
+  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(F, false);
+  SM.AddNewSourceBuffer(std::move(Buf), SMLoc());
 
-  return LLParser(Buf, SM, Err, &M).Run();
+  return LLParser(F.getBuffer(), SM, Err, &M).Run();
 }
 
-std::unique_ptr<Module> llvm::parseAssembly(std::unique_ptr<MemoryBuffer> F,
+std::unique_ptr<Module> llvm::parseAssembly(MemoryBufferRef F,
                                             SMDiagnostic &Err,
                                             LLVMContext &Context) {
   std::unique_ptr<Module> M =
-      make_unique<Module>(F->getBufferIdentifier(), Context);
+      make_unique<Module>(F.getBufferIdentifier(), Context);
 
-  if (parseAssemblyInto(std::move(F), *M, Err))
+  if (parseAssemblyInto(F, *M, Err))
     return nullptr;
 
   return std::move(M);
@@ -53,14 +52,12 @@ std::unique_ptr<Module> llvm::parseAssemblyFile(StringRef Filename,
     return nullptr;
   }
 
-  return parseAssembly(std::move(FileOrErr.get()), Err, Context);
+  return parseAssembly(FileOrErr.get()->getMemBufferRef(), Err, Context);
 }
 
 std::unique_ptr<Module> llvm::parseAssemblyString(StringRef AsmString,
                                                   SMDiagnostic &Err,
                                                   LLVMContext &Context) {
-  std::unique_ptr<MemoryBuffer> F(
-      MemoryBuffer::getMemBuffer(AsmString, "<string>"));
-
-  return parseAssembly(std::move(F), Err, Context);
+  MemoryBufferRef F(AsmString, "<string>");
+  return parseAssembly(F, Err, Context);
 }
diff --git a/lib/Bitcode/Reader/BitReader.cpp b/lib/Bitcode/Reader/BitReader.cpp
index b5886c16fa4..e21d29ac374 100644
--- a/lib/Bitcode/Reader/BitReader.cpp
+++ b/lib/Bitcode/Reader/BitReader.cpp
@@ -31,7 +31,7 @@ LLVMBool LLVMParseBitcodeInContext(LLVMContextRef ContextRef,
                                    LLVMModuleRef *OutModule,
                                    char **OutMessage) {
   ErrorOr<Module *> ModuleOrErr =
-      parseBitcodeFile(unwrap(MemBuf), *unwrap(ContextRef));
+      parseBitcodeFile(unwrap(MemBuf)->getMemBufferRef(), *unwrap(ContextRef));
   if (std::error_code EC = ModuleOrErr.getError()) {
     if (OutMessage)
       *OutMessage = strdup(EC.message().c_str());
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index e5dfa723b04..8dc0aa32315 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -3564,15 +3564,17 @@ Module *llvm::getStreamedBitcodeModule(const std::string &name,
   return M;
 }
 
-ErrorOr<Module *> llvm::parseBitcodeFile(MemoryBuffer *Buffer,
+ErrorOr<Module *> llvm::parseBitcodeFile(MemoryBufferRef Buffer,
                                          LLVMContext &Context) {
+  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
   ErrorOr<Module *> ModuleOrErr =
-      getLazyBitcodeModuleImpl(Buffer, Context, true);
+      getLazyBitcodeModuleImpl(Buf.get(), Context, true);
   if (!ModuleOrErr)
     return ModuleOrErr;
+  Buf.release(); // The BitcodeReader owns it now.
   Module *M = ModuleOrErr.get();
   // Read in the entire module, and destroy the BitcodeReader.
-  if (std::error_code EC = M->materializeAllPermanently(true)) {
+  if (std::error_code EC = M->materializeAllPermanently()) {
     delete M;
     return EC;
   }
@@ -3583,12 +3585,11 @@ ErrorOr<Module *> llvm::parseBitcodeFile(MemoryBuffer *Buffer,
   return M;
 }
 
-std::string llvm::getBitcodeTargetTriple(MemoryBuffer *Buffer,
+std::string llvm::getBitcodeTargetTriple(MemoryBufferRef Buffer,
                                          LLVMContext &Context) {
-  BitcodeReader *R = new BitcodeReader(Buffer, Context);
+  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Buffer, false);
+  auto R = llvm::make_unique<BitcodeReader>(Buf.get(), Context);
   ErrorOr<std::string> Triple = R->parseTriple();
-  R->releaseBuffer();
-  delete R;
   if (Triple.getError())
     return "";
   return Triple.get();
diff --git a/lib/Bitcode/Reader/BitcodeReader.h b/lib/Bitcode/Reader/BitcodeReader.h
index 6d4e0a2dfe9..c9525661ec1 100644
--- a/lib/Bitcode/Reader/BitcodeReader.h
+++ b/lib/Bitcode/Reader/BitcodeReader.h
@@ -221,7 +221,7 @@ public:
 
   void FreeState();
 
-  void releaseBuffer() override;
+  void releaseBuffer();
 
   bool isMaterializable(const GlobalValue *GV) const override;
   bool isDematerializable(const GlobalValue *GV) const override;
diff --git a/lib/IR/Module.cpp b/lib/IR/Module.cpp
index f1b1f9a2acc..98e4706019c 100644
--- a/lib/IR/Module.cpp
+++ b/lib/IR/Module.cpp
@@ -413,13 +413,10 @@ std::error_code Module::materializeAll() {
   return Materializer->MaterializeModule(this);
 }
 
-std::error_code Module::materializeAllPermanently(bool ReleaseBuffer) {
+std::error_code Module::materializeAllPermanently() {
   if (std::error_code EC = materializeAll())
     return EC;
 
-  if (ReleaseBuffer)
-    Materializer->releaseBuffer();
-
   Materializer.reset();
   return std::error_code();
 }
diff --git a/lib/IRReader/IRReader.cpp b/lib/IRReader/IRReader.cpp
index 259b41af24f..5c3124821a7 100644
--- a/lib/IRReader/IRReader.cpp
+++ b/lib/IRReader/IRReader.cpp
@@ -46,7 +46,7 @@ getLazyIRModule(std::unique_ptr<MemoryBuffer> Buffer, SMDiagnostic &Err,
     return std::unique_ptr<Module>(ModuleOrErr.get());
   }
 
-  return parseAssembly(std::move(Buffer), Err, Context);
+  return parseAssembly(Buffer->getMemBufferRef(), Err, Context);
 }
 
 std::unique_ptr<Module> llvm::getLazyIRFileModule(StringRef Filename,
@@ -63,24 +63,22 @@ std::unique_ptr<Module> llvm::getLazyIRFileModule(StringRef Filename,
   return getLazyIRModule(std::move(FileOrErr.get()), Err, Context);
 }
 
-std::unique_ptr<Module> llvm::parseIR(MemoryBuffer *Buffer, SMDiagnostic &Err,
+std::unique_ptr<Module> llvm::parseIR(MemoryBufferRef Buffer, SMDiagnostic &Err,
                                       LLVMContext &Context) {
   NamedRegionTimer T(TimeIRParsingName, TimeIRParsingGroupName,
                      TimePassesIsEnabled);
-  if (isBitcode((const unsigned char *)Buffer->getBufferStart(),
-                (const unsigned char *)Buffer->getBufferEnd())) {
+  if (isBitcode((const unsigned char *)Buffer.getBufferStart(),
+                (const unsigned char *)Buffer.getBufferEnd())) {
     ErrorOr<Module *> ModuleOrErr = parseBitcodeFile(Buffer, Context);
     if (std::error_code EC = ModuleOrErr.getError()) {
-      Err = SMDiagnostic(Buffer->getBufferIdentifier(), SourceMgr::DK_Error,
+      Err = SMDiagnostic(Buffer.getBufferIdentifier(), SourceMgr::DK_Error,
                          EC.message());
       return nullptr;
     }
     return std::unique_ptr<Module>(ModuleOrErr.get());
   }
 
-  return parseAssembly(std::unique_ptr<MemoryBuffer>(MemoryBuffer::getMemBuffer(
-                           Buffer->getBuffer(), Buffer->getBufferIdentifier())),
-                       Err, Context);
+  return parseAssembly(Buffer, Err, Context);
 }
 
 std::unique_ptr<Module> llvm::parseIRFile(StringRef Filename, SMDiagnostic &Err,
@@ -93,7 +91,7 @@ std::unique_ptr<Module> llvm::parseIRFile(StringRef Filename, SMDiagnostic &Err,
     return nullptr;
   }
 
-  return parseIR(FileOrErr.get().get(), Err, Context);
+  return parseIR(FileOrErr.get()->getMemBufferRef(), Err, Context);
 }
 
 //===----------------------------------------------------------------------===//
@@ -106,7 +104,8 @@ LLVMBool LLVMParseIRInContext(LLVMContextRef ContextRef,
   SMDiagnostic Diag;
 
   std::unique_ptr<MemoryBuffer> MB(unwrap(MemBuf));
-  *OutM = wrap(parseIR(MB.get(), Diag, *unwrap(ContextRef)).release());
+  *OutM =
+      wrap(parseIR(MB->getMemBufferRef(), Diag, *unwrap(ContextRef)).release());
 
   if(!*OutM) {
     if (OutMessage) {
diff --git a/lib/LTO/LTOModule.cpp b/lib/LTO/LTOModule.cpp
index f9d270d3207..76b5e197a62 100644
--- a/lib/LTO/LTOModule.cpp
+++ b/lib/LTO/LTOModule.cpp
@@ -65,7 +65,8 @@ bool LTOModule::isBitcodeFile(const char *path) {
 
 bool LTOModule::isBitcodeForTarget(MemoryBuffer *buffer,
                                    StringRef triplePrefix) {
-  std::string Triple = getBitcodeTargetTriple(buffer, getGlobalContext());
+  std::string Triple =
+      getBitcodeTargetTriple(buffer->getMemBufferRef(), getGlobalContext());
   return StringRef(Triple).startswith(triplePrefix);
 }
 
@@ -112,14 +113,7 @@ LTOModule *LTOModule::createFromBuffer(const void *mem, size_t length,
 LTOModule *LTOModule::makeLTOModule(MemoryBufferRef Buffer,
                                     TargetOptions options,
                                     std::string &errMsg) {
-  StringRef Data = Buffer.getBuffer();
-  StringRef FileName = Buffer.getBufferIdentifier();
-  std::unique_ptr<MemoryBuffer> MemBuf(
-      makeBuffer(Data.begin(), Data.size(), FileName));
-  if (!MemBuf)
-    return nullptr;
-
-  ErrorOr<Module *> MOrErr = parseBitcodeFile(MemBuf.get(), getGlobalContext());
+  ErrorOr<Module *> MOrErr = parseBitcodeFile(Buffer, getGlobalContext());
   if (std::error_code EC = MOrErr.getError()) {
     errMsg = EC.message();
     return nullptr;
diff --git a/lib/Object/IRObjectFile.cpp b/lib/Object/IRObjectFile.cpp
index 2ef359c7f00..964c7ed691d 100644
--- a/lib/Object/IRObjectFile.cpp
+++ b/lib/Object/IRObjectFile.cpp
@@ -268,10 +268,7 @@ ErrorOr<IRObjectFile *>
 llvm::object::IRObjectFile::createIRObjectFile(MemoryBufferRef Object,
                                                LLVMContext &Context) {
 
-  StringRef Data = Object.getBuffer();
-  StringRef FileName = Object.getBufferIdentifier();
-  std::unique_ptr<MemoryBuffer> Buff(
-      MemoryBuffer::getMemBuffer(Data, FileName, false));
+  std::unique_ptr<MemoryBuffer> Buff(MemoryBuffer::getMemBuffer(Object, false));
 
   ErrorOr<Module *> MOrErr = getLazyBitcodeModule(Buff.get(), Context);
   if (std::error_code EC = MOrErr.getError())
diff --git a/lib/Support/MemoryBuffer.cpp b/lib/Support/MemoryBuffer.cpp
index 27edce67361..9bb6b42466b 100644
--- a/lib/Support/MemoryBuffer.cpp
+++ b/lib/Support/MemoryBuffer.cpp
@@ -103,6 +103,12 @@ MemoryBuffer *MemoryBuffer::getMemBuffer(StringRef InputData,
       MemoryBufferMem(InputData, RequiresNullTerminator);
 }
 
+std::unique_ptr<MemoryBuffer>
+MemoryBuffer::getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator) {
+  return std::unique_ptr<MemoryBuffer>(getMemBuffer(
+      Ref.getBuffer(), Ref.getBufferIdentifier(), RequiresNullTerminator));
+}
+
 /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
 /// copying the contents and taking ownership of it.  This has no requirements
 /// on EndPtr[0].
diff --git a/tools/verify-uselistorder/verify-uselistorder.cpp b/tools/verify-uselistorder/verify-uselistorder.cpp
index c796c389bec..992a5b0839d 100644
--- a/tools/verify-uselistorder/verify-uselistorder.cpp
+++ b/tools/verify-uselistorder/verify-uselistorder.cpp
@@ -157,7 +157,8 @@ std::unique_ptr<Module> TempFile::readBitcode(LLVMContext &Context) const {
   }
 
   MemoryBuffer *Buffer = BufferOr.get().get();
-  ErrorOr<Module *> ModuleOr = parseBitcodeFile(Buffer, Context);
+  ErrorOr<Module *> ModuleOr =
+      parseBitcodeFile(Buffer->getMemBufferRef(), Context);
   if (!ModuleOr) {
     DEBUG(dbgs() << "error: " << ModuleOr.getError().message() << "\n");
     return nullptr;