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

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index 4e65d444fc8..6af827683e1 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -66,16 +66,17 @@ DumpType("debug-dump", cl::init(DIDT_All),
         clEnumValEnd));
 
 static void DumpInput(const 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() << Filename << ": " << EC.message() << "\n";
     return;
   }
+  std::unique_ptr<MemoryBuffer> Buff = std::move(BuffOrErr.get());
 
   ErrorOr<std::unique_ptr<ObjectFile>> ObjOrErr =
-      ObjectFile::createObjectFile(Buff.get());
+      ObjectFile::createObjectFile(Buff->getMemBufferRef());
   if (std::error_code EC = ObjOrErr.getError()) {
     errs() << Filename << ": " << EC.message() << '\n';
     return;