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/ObjectFile.cpp | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

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

diff --git a/llvm/lib/Object/ObjectFile.cpp b/llvm/lib/Object/ObjectFile.cpp
index 0e77541dec5..9565d02f35a 100644
--- a/llvm/lib/Object/ObjectFile.cpp
+++ b/llvm/lib/Object/ObjectFile.cpp
@@ -25,8 +25,8 @@ using namespace object;
 
 void ObjectFile::anchor() { }
 
-ObjectFile::ObjectFile(unsigned int Type, std::unique_ptr<MemoryBuffer> Source)
-    : SymbolicFile(Type, std::move(Source)) {}
+ObjectFile::ObjectFile(unsigned int Type, MemoryBufferRef Source)
+    : SymbolicFile(Type, Source) {}
 
 std::error_code ObjectFile::printSymbolName(raw_ostream &OS,
                                             DataRefImpl Symb) const {
@@ -48,10 +48,10 @@ section_iterator ObjectFile::getRelocatedSection(DataRefImpl Sec) const {
 }
 
 ErrorOr<std::unique_ptr<ObjectFile>>
-ObjectFile::createObjectFile(std::unique_ptr<MemoryBuffer> &Object,
-                             sys::fs::file_magic Type) {
+ObjectFile::createObjectFile(MemoryBufferRef Object, sys::fs::file_magic Type) {
+  StringRef Data = Object.getBuffer();
   if (Type == sys::fs::file_magic::unknown)
-    Type = sys::fs::identify_magic(Object->getBuffer());
+    Type = sys::fs::identify_magic(Data);
 
   switch (Type) {
   case sys::fs::file_magic::unknown:
@@ -79,16 +79,24 @@ ObjectFile::createObjectFile(std::unique_ptr<MemoryBuffer> &Object,
   case sys::fs::file_magic::coff_object:
   case sys::fs::file_magic::coff_import_library:
   case sys::fs::file_magic::pecoff_executable:
-    return createCOFFObjectFile(std::move(Object));
+    return createCOFFObjectFile(Object);
   }
   llvm_unreachable("Unexpected Object File Type");
 }
 
-ErrorOr<std::unique_ptr<ObjectFile>>
+ErrorOr<OwningBinary<ObjectFile>>
 ObjectFile::createObjectFile(StringRef ObjectPath) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
       MemoryBuffer::getFile(ObjectPath);
   if (std::error_code EC = FileOrErr.getError())
     return EC;
-  return createObjectFile(FileOrErr.get());
+  std::unique_ptr<MemoryBuffer> Buffer = std::move(FileOrErr.get());
+
+  ErrorOr<std::unique_ptr<ObjectFile>> ObjOrErr =
+      createObjectFile(Buffer->getMemBufferRef());
+  if (std::error_code EC = ObjOrErr.getError())
+    return EC;
+  std::unique_ptr<ObjectFile> Obj = std::move(ObjOrErr.get());
+
+  return OwningBinary<ObjectFile>(std::move(Obj), std::move(Buffer));
 }
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