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, 15 insertions, 14 deletions

diff --git a/llvm/tools/llvm-ar/llvm-ar.cpp b/llvm/tools/llvm-ar/llvm-ar.cpp
index 3d87597f39b..2b32098a490 100644
--- a/llvm/tools/llvm-ar/llvm-ar.cpp
+++ b/llvm/tools/llvm-ar/llvm-ar.cpp
@@ -686,7 +686,7 @@ static void writeStringTable(raw_fd_ostream &Out,
 
 static void
 writeSymbolTable(raw_fd_ostream &Out, ArrayRef<NewArchiveIterator> Members,
-                 MutableArrayRef<std::unique_ptr<MemoryBuffer>> Buffers,
+                 ArrayRef<MemoryBufferRef> Buffers,
                  std::vector<std::pair<unsigned, unsigned>> &MemberOffsetRefs) {
   unsigned StartOffset = 0;
   unsigned MemberNum = 0;
@@ -697,7 +697,7 @@ writeSymbolTable(raw_fd_ostream &Out, ArrayRef<NewArchiveIterator> Members,
   for (ArrayRef<NewArchiveIterator>::iterator I = Members.begin(),
                                               E = Members.end();
        I != E; ++I, ++MemberNum) {
-    std::unique_ptr<MemoryBuffer> &MemberBuffer = Buffers[MemberNum];
+    MemoryBufferRef MemberBuffer = Buffers[MemberNum];
     ErrorOr<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
         object::SymbolicFile::createSymbolicFile(
             MemberBuffer, sys::fs::file_magic::unknown, &Context);
@@ -725,7 +725,6 @@ writeSymbolTable(raw_fd_ostream &Out, ArrayRef<NewArchiveIterator> Members,
       MemberOffsetRefs.push_back(std::make_pair(Out.tell(), MemberNum));
       print32BE(Out, 0);
     }
-    MemberBuffer.reset(Obj.releaseBuffer());
   }
   Out << NameOS.str();
 
@@ -759,12 +758,12 @@ static void performWriteOperation(ArchiveOperation Operation,
 
   std::vector<std::pair<unsigned, unsigned> > MemberOffsetRefs;
 
-  std::vector<std::unique_ptr<MemoryBuffer>> MemberBuffers;
-  MemberBuffers.resize(NewMembers.size());
+  std::vector<std::unique_ptr<MemoryBuffer>> Buffers;
+  std::vector<MemoryBufferRef> Members;
 
   for (unsigned I = 0, N = NewMembers.size(); I < N; ++I) {
-    std::unique_ptr<MemoryBuffer> &MemberBuffer = MemberBuffers[I];
     NewArchiveIterator &Member = NewMembers[I];
+    MemoryBufferRef MemberRef;
 
     if (Member.isNewMember()) {
       const char *Filename = Member.getNew();
@@ -773,18 +772,20 @@ static void performWriteOperation(ArchiveOperation Operation,
       ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
           MemoryBuffer::getOpenFile(FD, Filename, Status.getSize(), false);
       failIfError(MemberBufferOrErr.getError(), Filename);
-      MemberBuffer = std::move(MemberBufferOrErr.get());
+      Buffers.push_back(std::move(MemberBufferOrErr.get()));
+      MemberRef = Buffers.back()->getMemBufferRef();
     } else {
       object::Archive::child_iterator OldMember = Member.getOld();
-      ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
-          OldMember->getMemoryBuffer();
+      ErrorOr<MemoryBufferRef> MemberBufferOrErr =
+          OldMember->getMemoryBufferRef();
       failIfError(MemberBufferOrErr.getError());
-      MemberBuffer = std::move(MemberBufferOrErr.get());
+      MemberRef = MemberBufferOrErr.get();
     }
+    Members.push_back(MemberRef);
   }
 
   if (Symtab) {
-    writeSymbolTable(Out, NewMembers, MemberBuffers, MemberOffsetRefs);
+    writeSymbolTable(Out, NewMembers, Members, MemberOffsetRefs);
   }
 
   std::vector<unsigned> StringMapIndexes;
@@ -808,7 +809,7 @@ static void performWriteOperation(ArchiveOperation Operation,
     }
     Out.seek(Pos);
 
-    const MemoryBuffer *File = MemberBuffers[MemberNum].get();
+    MemoryBufferRef File = Members[MemberNum];
     if (I->isNewMember()) {
       const char *FileName = I->getNew();
       const sys::fs::file_status &Status = I->getStatus();
@@ -838,7 +839,7 @@ static void performWriteOperation(ArchiveOperation Operation,
                           OldMember->getSize());
     }
 
-    Out << File->getBuffer();
+    Out << File.getBuffer();
 
     if (Out.tell() % 2)
       Out << '\n';
@@ -943,7 +944,7 @@ static int performOperation(ArchiveOperation Operation) {
   }
 
   if (!EC) {
-    object::Archive Archive(std::move(Buf.get()), EC);
+    object::Archive Archive(Buf.get()->getMemBufferRef(), EC);
 
     if (EC) {
       errs() << ToolName << ": error loading '" << ArchiveName