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/SmallVector.h"
19#include "llvm/Support/MemoryBuffer.h"
20#include "llvm/Support/raw_ostream.h"
21
22namespace llvm {
23
24/// ObjectBuffer - This class acts as a container for the memory buffer used during
25/// generation and loading of executable objects using MCJIT and RuntimeDyld.  The
26/// underlying memory for the object will be owned by the ObjectBuffer instance
27/// throughout its lifetime.  The getMemBuffer() method provides a way to create a
28/// MemoryBuffer wrapper object instance to be owned by other classes (such as
29/// ObjectFile) as needed, but the MemoryBuffer instance returned does not own the
30/// actual memory it points to.
31class ObjectBuffer {
32  virtual void anchor();
33public:
34  ObjectBuffer() {}
35  ObjectBuffer(MemoryBuffer* Buf) : Buffer(Buf) {}
36  virtual ~ObjectBuffer() {}
37
38  /// getMemBuffer - Like MemoryBuffer::getMemBuffer() this function
39  /// returns a pointer to an object that is owned by the caller. However,
40  /// the caller does not take ownership of the underlying memory.
41  MemoryBuffer *getMemBuffer() const {
42    return MemoryBuffer::getMemBuffer(Buffer->getBuffer(),
43                                      Buffer->getBufferIdentifier(), false);
44  }
45
46  const char *getBufferStart() const { return Buffer->getBufferStart(); }
47  size_t getBufferSize() const { return Buffer->getBufferSize(); }
48  StringRef getBuffer() const { return Buffer->getBuffer(); }
49
50protected:
51  // The memory contained in an ObjectBuffer
52  std::unique_ptr<MemoryBuffer> Buffer;
53};
54
55/// ObjectBufferStream - This class encapsulates the SmallVector and
56/// raw_svector_ostream needed to generate an object using MC code emission
57/// while providing a common ObjectBuffer interface for access to the
58/// memory once the object has been generated.
59class ObjectBufferStream : public ObjectBuffer {
60  void anchor() override;
61public:
62  ObjectBufferStream() : OS(SV) {}
63  virtual ~ObjectBufferStream() {}
64
65  raw_ostream &getOStream() { return OS; }
66  void flush()
67  {
68    OS.flush();
69
70    // Make the data accessible via the ObjectBuffer::Buffer
71    Buffer.reset(MemoryBuffer::getMemBuffer(StringRef(SV.data(), SV.size()),
72                                            "",
73                                            false));
74  }
75
76protected:
77  SmallVector<char, 4096> SV; // Working buffer into which we JIT.
78  raw_svector_ostream     OS; // streaming wrapper
79};
80
81} // namespace llvm
82
83#endif
84