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 22 namespace 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. 31 class ObjectBuffer { 32 virtual void anchor(); 33 public: ObjectBuffer()34 ObjectBuffer() {} ObjectBuffer(MemoryBuffer * Buf)35 ObjectBuffer(MemoryBuffer* Buf) : Buffer(Buf) {} ~ObjectBuffer()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. getMemBuffer()41 MemoryBuffer *getMemBuffer() const { 42 return MemoryBuffer::getMemBuffer(Buffer->getBuffer(), 43 Buffer->getBufferIdentifier(), false); 44 } 45 getBufferStart()46 const char *getBufferStart() const { return Buffer->getBufferStart(); } getBufferSize()47 size_t getBufferSize() const { return Buffer->getBufferSize(); } getBuffer()48 StringRef getBuffer() const { return Buffer->getBuffer(); } 49 50 protected: 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. 59 class ObjectBufferStream : public ObjectBuffer { 60 void anchor() override; 61 public: ObjectBufferStream()62 ObjectBufferStream() : OS(SV) {} ~ObjectBufferStream()63 virtual ~ObjectBufferStream() {} 64 getOStream()65 raw_ostream &getOStream() { return OS; } flush()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 76 protected: 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