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/Archive.cpp | 35 +++++++++++++----------------------
 1 file changed, 13 insertions(+), 22 deletions(-)

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

diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 45156f1311e..070fe812eec 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -109,7 +109,7 @@ Archive::Child Archive::Child::getNext() const {
   const char *NextLoc = Data.data() + SpaceToSkip;
 
   // Check to see if this is past the end of the archive.
-  if (NextLoc >= Parent->Data->getBufferEnd())
+  if (NextLoc >= Parent->Data.getBufferEnd())
     return Child(Parent, nullptr);
 
   return Child(Parent, NextLoc);
@@ -159,45 +159,36 @@ ErrorOr<StringRef> Archive::Child::getName() const {
   return name;
 }
 
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-Archive::Child::getMemoryBuffer(bool FullPath) const {
+ErrorOr<MemoryBufferRef> Archive::Child::getMemoryBufferRef() const {
   ErrorOr<StringRef> NameOrErr = getName();
   if (std::error_code EC = NameOrErr.getError())
     return EC;
   StringRef Name = NameOrErr.get();
-  SmallString<128> Path;
-  std::unique_ptr<MemoryBuffer> Ret(MemoryBuffer::getMemBuffer(
-      getBuffer(),
-      FullPath
-          ? (Twine(Parent->getFileName()) + "(" + Name + ")").toStringRef(Path)
-          : Name,
-      false));
-  return std::move(Ret);
+  return MemoryBufferRef(getBuffer(), Name);
 }
 
 ErrorOr<std::unique_ptr<Binary>>
 Archive::Child::getAsBinary(LLVMContext *Context) const {
-  ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr = getMemoryBuffer();
+  ErrorOr<MemoryBufferRef> BuffOrErr = getMemoryBufferRef();
   if (std::error_code EC = BuffOrErr.getError())
     return EC;
 
-  return createBinary(std::move(*BuffOrErr), Context);
+  return createBinary(BuffOrErr.get(), Context);
 }
 
-ErrorOr<std::unique_ptr<Archive>>
-Archive::create(std::unique_ptr<MemoryBuffer> Source) {
+ErrorOr<std::unique_ptr<Archive>> Archive::create(MemoryBufferRef Source) {
   std::error_code EC;
-  std::unique_ptr<Archive> Ret(new Archive(std::move(Source), EC));
+  std::unique_ptr<Archive> Ret(new Archive(Source, EC));
   if (EC)
     return EC;
   return std::move(Ret);
 }
 
-Archive::Archive(std::unique_ptr<MemoryBuffer> Source, std::error_code &ec)
-    : Binary(Binary::ID_Archive, std::move(Source)), SymbolTable(child_end()) {
+Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
+    : Binary(Binary::ID_Archive, Source), SymbolTable(child_end()) {
   // Check for sufficient magic.
-  if (Data->getBufferSize() < 8 ||
-      StringRef(Data->getBufferStart(), 8) != Magic) {
+  if (Data.getBufferSize() < 8 ||
+      StringRef(Data.getBufferStart(), 8) != Magic) {
     ec = object_error::invalid_file_type;
     return;
   }
@@ -311,13 +302,13 @@ Archive::Archive(std::unique_ptr<MemoryBuffer> Source, std::error_code &ec)
 }
 
 Archive::child_iterator Archive::child_begin(bool SkipInternal) const {
-  if (Data->getBufferSize() == 8) // empty archive.
+  if (Data.getBufferSize() == 8) // empty archive.
     return child_end();
 
   if (SkipInternal)
     return FirstRegular;
 
-  const char *Loc = Data->getBufferStart() + strlen(Magic);
+  const char *Loc = Data.getBufferStart() + strlen(Magic);
   Child c(this, Loc);
   return c;
 }
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