ReaderWriter.h revision 4434ed44c45c87a72b7a0bf2f91211f895022b91
1//===-- llvm/Bitcode/ReaderWriter.h - Bitcode reader/writers ----*- C++ -*-===// 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 header defines interfaces to read and write LLVM bitcode files/streams. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_BITCODE_H 15#define LLVM_BITCODE_H 16 17#include <iosfwd> 18#include <string> 19 20namespace llvm { 21 class Module; 22 class ModuleProvider; 23 class MemoryBuffer; 24 class ModulePass; 25 class BitstreamWriter; 26 class LLVMContext; 27 class raw_ostream; 28 29 /// getBitcodeModuleProvider - Read the header of the specified bitcode buffer 30 /// and prepare for lazy deserialization of function bodies. If successful, 31 /// this takes ownership of 'buffer' and returns a non-null pointer. On 32 /// error, this returns null, *does not* take ownership of Buffer, and fills 33 /// in *ErrMsg with an error description if ErrMsg is non-null. 34 ModuleProvider *getBitcodeModuleProvider(MemoryBuffer *Buffer, 35 LLVMContext& Context, 36 std::string *ErrMsg = 0); 37 38 /// ParseBitcodeFile - Read the specified bitcode file, returning the module. 39 /// If an error occurs, this returns null and fills in *ErrMsg if it is 40 /// non-null. This method *never* takes ownership of Buffer. 41 Module *ParseBitcodeFile(MemoryBuffer *Buffer, LLVMContext& Context, 42 std::string *ErrMsg = 0); 43 44 /// WriteBitcodeToFile - Write the specified module to the specified output 45 /// stream. 46 void WriteBitcodeToFile(const Module *M, std::ostream &Out); 47 48 /// WriteBitcodeToFile - Write the specified module to the specified 49 /// raw output stream. 50 void WriteBitcodeToFile(const Module *M, raw_ostream &Out); 51 52 /// WriteBitcodeToStream - Write the specified module to the specified 53 /// raw output stream. 54 void WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream); 55 56 /// CreateBitcodeWriterPass - Create and return a pass that writes the module 57 /// to the specified ostream. 58 ModulePass *CreateBitcodeWriterPass(std::ostream &Str); 59 60 /// createBitcodeWriterPass - Create and return a pass that writes the module 61 /// to the specified ostream. 62 ModulePass *createBitcodeWriterPass(raw_ostream &Str); 63 64 65 /// isBitcodeWrapper - Return true fi this is a wrapper for LLVM IR bitcode 66 /// files. 67 static bool inline isBitcodeWrapper(unsigned char *BufPtr, 68 unsigned char *BufEnd) { 69 return (BufPtr != BufEnd && BufPtr[0] == 0xDE && BufPtr[1] == 0xC0 && 70 BufPtr[2] == 0x17 && BufPtr[3] == 0x0B); 71 } 72 73 /// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special 74 /// header for padding or other reasons. The format of this header is: 75 /// 76 /// struct bc_header { 77 /// uint32_t Magic; // 0x0B17C0DE 78 /// uint32_t Version; // Version, currently always 0. 79 /// uint32_t BitcodeOffset; // Offset to traditional bitcode file. 80 /// uint32_t BitcodeSize; // Size of traditional bitcode file. 81 /// ... potentially other gunk ... 82 /// }; 83 /// 84 /// This function is called when we find a file with a matching magic number. 85 /// In this case, skip down to the subsection of the file that is actually a 86 /// BC file. 87 static inline bool SkipBitcodeWrapperHeader(unsigned char *&BufPtr, 88 unsigned char *&BufEnd) { 89 enum { 90 KnownHeaderSize = 4*4, // Size of header we read. 91 OffsetField = 2*4, // Offset in bytes to Offset field. 92 SizeField = 3*4 // Offset in bytes to Size field. 93 }; 94 95 // Must contain the header! 96 if (BufEnd-BufPtr < KnownHeaderSize) return true; 97 98 unsigned Offset = ( BufPtr[OffsetField ] | 99 (BufPtr[OffsetField+1] << 8) | 100 (BufPtr[OffsetField+2] << 16) | 101 (BufPtr[OffsetField+3] << 24)); 102 unsigned Size = ( BufPtr[SizeField ] | 103 (BufPtr[SizeField +1] << 8) | 104 (BufPtr[SizeField +2] << 16) | 105 (BufPtr[SizeField +3] << 24)); 106 107 // Verify that Offset+Size fits in the file. 108 if (Offset+Size > unsigned(BufEnd-BufPtr)) 109 return true; 110 BufPtr += Offset; 111 BufEnd = BufPtr+Size; 112 return false; 113 } 114} // End llvm namespace 115 116#endif 117