ObjectBuffer.h revision 5a364c5561ec04e33a6f5d52c14f1bac6f247ea0 
1//===---- ObjectBuffer.h - Utility class to wrap object image memory -----===//
2//
3//		       The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file declares a wrapper class to hold the memory into which an
11// object will be generated.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_EXECUTIONENGINE_OBJECTBUFFER_H
16#define LLVM_EXECUTIONENGINE_OBJECTBUFFER_H
17
18#include "llvm/ADT/OwningPtr.h"
19#include "llvm/ADT/SmallVector.h"
20#include "llvm/Support/MemoryBuffer.h"
21#include "llvm/Support/raw_ostream.h"
22
23namespace llvm {
24
25/// ObjectBuffer - This class acts as a container for the memory buffer used during
26/// generation and loading of executable objects using MCJIT and RuntimeDyld.  The
27/// underlying memory for the object will be owned by the ObjectBuffer instance
28/// throughout its lifetime.  The getMemBuffer() method provides a way to create a
29/// MemoryBuffer wrapper object instance to be owned by other classes (such as
30/// ObjectFile) as needed, but the MemoryBuffer instance returned does not own the
31/// actual memory it points to.
32class ObjectBuffer {
33public:
34  ObjectBuffer() {}
35  ObjectBuffer(MemoryBuffer* Buf) : Buffer(Buf) {}
36
37  /// getMemBuffer - Like MemoryBuffer::getMemBuffer() this function
38  /// returns a pointer to an object that is owned by the caller. However,
39  /// the caller does not take ownership of the underlying memory.
40  MemoryBuffer *getMemBuffer() const {
41    return MemoryBuffer::getMemBuffer(Buffer->getBuffer(), "", false);
42  }
43
44  const char *getBufferStart() const { return Buffer->getBufferStart(); }
45  size_t getBufferSize() const { return Buffer->getBufferSize(); }
46  StringRef getBuffer() const { return Buffer->getBuffer(); }
47
48protected:
49  // The memory contained in an ObjectBuffer
50  OwningPtr<MemoryBuffer> Buffer;
51};
52
53/// ObjectBufferStream - This class encapsulates the SmallVector and
54/// raw_svector_ostream needed to generate an object using MC code emission
55/// while providing a common ObjectBuffer interface for access to the
56/// memory once the object has been generated.
57class ObjectBufferStream : public ObjectBuffer {
58public:
59  ObjectBufferStream() : OS(SV) {}
60
61  raw_ostream &getOStream() { return OS; }
62  void flush()
63  {
64    OS.flush();
65
66    // Make the data accessible via the ObjectBuffer::Buffer
67    Buffer.reset(MemoryBuffer::getMemBuffer(StringRef(SV.data(), SV.size()),
68					    "",
69					    false));
70  }
71
72protected:
73  SmallVector<char, 4096> SV; // Working buffer into which we JIT.
74  raw_svector_ostream	  OS; // streaming wrapper
75};
76
77} // namespace llvm
78
79#endif
80