From 48af1c2a1a5148bc6a143bc0d8650ef744f2f7c3 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 19 Aug 2014 18:44:46 +0000
Subject: 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
---
 llvm/lib/Object/Binary.cpp | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

(limited to 'llvm/lib/Object/Binary.cpp')

diff --git a/llvm/lib/Object/Binary.cpp b/llvm/lib/Object/Binary.cpp
index 89e9d732ce9..d23ee590569 100644
--- a/llvm/lib/Object/Binary.cpp
+++ b/llvm/lib/Object/Binary.cpp
@@ -27,25 +27,22 @@ using namespace object;
 
 Binary::~Binary() {}
 
-Binary::Binary(unsigned int Type, std::unique_ptr<MemoryBuffer> Source)
-    : TypeID(Type), Data(std::move(Source)) {}
+Binary::Binary(unsigned int Type, MemoryBufferRef Source)
+    : TypeID(Type), Data(Source) {}
 
-StringRef Binary::getData() const {
-  return Data->getBuffer();
-}
+StringRef Binary::getData() const { return Data.getBuffer(); }
 
-StringRef Binary::getFileName() const {
-  return Data->getBufferIdentifier();
-}
+StringRef Binary::getFileName() const { return Data.getBufferIdentifier(); }
+
+MemoryBufferRef Binary::getMemoryBufferRef() const { return Data; }
 
-ErrorOr<std::unique_ptr<Binary>>
-object::createBinary(std::unique_ptr<MemoryBuffer> Buffer,
-                     LLVMContext *Context) {
-  sys::fs::file_magic Type = sys::fs::identify_magic(Buffer->getBuffer());
+ErrorOr<std::unique_ptr<Binary>> object::createBinary(MemoryBufferRef Buffer,
+                                                      LLVMContext *Context) {
+  sys::fs::file_magic Type = sys::fs::identify_magic(Buffer.getBuffer());
 
   switch (Type) {
     case sys::fs::file_magic::archive:
-      return Archive::create(std::move(Buffer));
+      return Archive::create(Buffer);
     case sys::fs::file_magic::elf_relocatable:
     case sys::fs::file_magic::elf_executable:
     case sys::fs::file_magic::elf_shared_object:
@@ -66,7 +63,7 @@ object::createBinary(std::unique_ptr<MemoryBuffer> Buffer,
     case sys::fs::file_magic::bitcode:
       return ObjectFile::createSymbolicFile(Buffer, Type, Context);
     case sys::fs::file_magic::macho_universal_binary:
-      return MachOUniversalBinary::create(std::move(Buffer));
+      return MachOUniversalBinary::create(Buffer);
     case sys::fs::file_magic::unknown:
     case sys::fs::file_magic::windows_resource:
       // Unrecognized object file format.
@@ -75,10 +72,18 @@ object::createBinary(std::unique_ptr<MemoryBuffer> Buffer,
   llvm_unreachable("Unexpected Binary File Type");
 }
 
-ErrorOr<std::unique_ptr<Binary>> object::createBinary(StringRef Path) {
+ErrorOr<OwningBinary<Binary>> object::createBinary(StringRef Path) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
       MemoryBuffer::getFileOrSTDIN(Path);
   if (std::error_code EC = FileOrErr.getError())
     return EC;
-  return createBinary(std::move(*FileOrErr));
+  std::unique_ptr<MemoryBuffer> &Buffer = FileOrErr.get();
+
+  ErrorOr<std::unique_ptr<Binary>> BinOrErr =
+      createBinary(Buffer->getMemBufferRef());
+  if (std::error_code EC = BinOrErr.getError())
+    return EC;
+  std::unique_ptr<Binary> &Bin = BinOrErr.get();
+
+  return OwningBinary<Binary>(std::move(Bin), std::move(Buffer));
 }
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