Don't own the buffer in object::Binary.

Owning the buffer is somewhat inflexible. Some Binaries have sub Binaries
(like Archive) and we had to create dummy buffers just to handle that. It is
also a bad fit for IRObjectFile where the Module wants to own the buffer too.

Keeping this ownership would make supporting IR inside native objects
particularly painful.

This patch focuses in lib/Object. If something elsewhere used to own an Binary,
now it also owns a MemoryBuffer.

This patch introduces a few new types.

* MemoryBufferRef. This is just a pair of StringRefs for the data and name.
  This is to MemoryBuffer as StringRef is to std::string.
* OwningBinary. A combination of Binary and a MemoryBuffer. This is needed
  for convenience functions that take a filename and return both the
  buffer and the Binary using that buffer.

The C api now uses OwningBinary to avoid any change in semantics. I will start
a new thread to see if we want to change it and how.

llvm-svn: 216002

2 files changed, 13 insertions, 9 deletions

diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index 1cf92360054..de99bea15aa 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -210,15 +210,16 @@ static void DisassembleInputMachO2(StringRef Filename,
                                    MachOObjectFile *MachOOF);
 
 void llvm::DisassembleInputMachO(StringRef Filename) {
-  ErrorOr<std::unique_ptr<MemoryBuffer>> Buff =
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr =
       MemoryBuffer::getFileOrSTDIN(Filename);
-  if (std::error_code EC = Buff.getError()) {
+  if (std::error_code EC = BuffOrErr.getError()) {
     errs() << "llvm-objdump: " << Filename << ": " << EC.message() << "\n";
     return;
   }
+  std::unique_ptr<MemoryBuffer> Buff = std::move(BuffOrErr.get());
 
-  std::unique_ptr<MachOObjectFile> MachOOF =
-    std::move(ObjectFile::createMachOObjectFile(Buff.get()).get());
+  std::unique_ptr<MachOObjectFile> MachOOF = std::move(
+      ObjectFile::createMachOObjectFile(Buff.get()->getMemBufferRef()).get());
 
   DisassembleInputMachO2(Filename, MachOOF.get());
 }
@@ -352,13 +353,16 @@ static void DisassembleInputMachO2(StringRef Filename,
     // A separate DSym file path was specified, parse it as a macho file,
     // get the sections and supply it to the section name parsing machinery.
     if (!DSYMFile.empty()) {
-      ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
+      ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
           MemoryBuffer::getFileOrSTDIN(DSYMFile);
-      if (std::error_code EC = Buf.getError()) {
+      if (std::error_code EC = BufOrErr.getError()) {
         errs() << "llvm-objdump: " << Filename << ": " << EC.message() << '\n';
         return;
       }
-      DbgObj = ObjectFile::createMachOObjectFile(Buf.get()).get().release();
+      DbgObj =
+          ObjectFile::createMachOObjectFile(BufOrErr.get()->getMemBufferRef())
+              .get()
+              .release();
     }
 
     // Setup the DIContext
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 791011ddefa..0074271ba7e 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -892,12 +892,12 @@ static void DumpInput(StringRef file) {
   }
 
   // Attempt to open the binary.
-  ErrorOr<std::unique_ptr<Binary>> BinaryOrErr = createBinary(file);
+  ErrorOr<OwningBinary<Binary>> BinaryOrErr = createBinary(file);
   if (std::error_code EC = BinaryOrErr.getError()) {
     errs() << ToolName << ": '" << file << "': " << EC.message() << ".\n";
     return;
   }
-  Binary &Binary = *BinaryOrErr.get();
+  Binary &Binary = *BinaryOrErr.get().getBinary();
 
   if (Archive *a = dyn_cast<Archive>(&Binary))
     DumpArchive(a);