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 <string> 18 19 namespace llvm { 20 class Module; 21 class MemoryBuffer; 22 class ModulePass; 23 class BitstreamWriter; 24 class LLVMContext; 25 class raw_ostream; 26 27 /// getLazyBitcodeModule - Read the header of the specified bitcode buffer 28 /// and prepare for lazy deserialization of function bodies. If successful, 29 /// this takes ownership of 'buffer' and returns a non-null pointer. On 30 /// error, this returns null, *does not* take ownership of Buffer, and fills 31 /// in *ErrMsg with an error description if ErrMsg is non-null. 32 Module *getLazyBitcodeModule(MemoryBuffer *Buffer, 33 LLVMContext& Context, 34 std::string *ErrMsg = 0); 35 36 /// getBitcodeTargetTriple - Read the header of the specified bitcode 37 /// buffer and extract just the triple information. If successful, 38 /// this returns a string and *does not* take ownership 39 /// of 'buffer'. On error, this returns "", and fills in *ErrMsg 40 /// if ErrMsg is non-null. 41 std::string getBitcodeTargetTriple(MemoryBuffer *Buffer, 42 LLVMContext& Context, 43 std::string *ErrMsg = 0); 44 45 /// ParseBitcodeFile - Read the specified bitcode file, returning the module. 46 /// If an error occurs, this returns null and fills in *ErrMsg if it is 47 /// non-null. This method *never* takes ownership of Buffer. 48 Module *ParseBitcodeFile(MemoryBuffer *Buffer, LLVMContext& Context, 49 std::string *ErrMsg = 0); 50 51 /// WriteBitcodeToFile - Write the specified module to the specified 52 /// raw output stream. For streams where it matters, the given stream 53 /// should be in "binary" mode. 54 void WriteBitcodeToFile(const Module *M, raw_ostream &Out); 55 56 /// WriteBitcodeToStream - Write the specified module to the specified 57 /// raw output stream. 58 void WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream); 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 if the given bytes are the magic bytes 66 /// for an LLVM IR bitcode wrapper. 67 /// isBitcodeWrapper(const unsigned char * BufPtr,const unsigned char * BufEnd)68 static inline bool isBitcodeWrapper(const unsigned char *BufPtr, 69 const unsigned char *BufEnd) { 70 // See if you can find the hidden message in the magic bytes :-). 71 // (Hint: it's a little-endian encoding.) 72 return BufPtr != BufEnd && 73 BufPtr[0] == 0xDE && 74 BufPtr[1] == 0xC0 && 75 BufPtr[2] == 0x17 && 76 BufPtr[3] == 0x0B; 77 } 78 79 /// isRawBitcode - Return true if the given bytes are the magic bytes for 80 /// raw LLVM IR bitcode (without a wrapper). 81 /// isRawBitcode(const unsigned char * BufPtr,const unsigned char * BufEnd)82 static inline bool isRawBitcode(const unsigned char *BufPtr, 83 const unsigned char *BufEnd) { 84 // These bytes sort of have a hidden message, but it's not in 85 // little-endian this time, and it's a little redundant. 86 return BufPtr != BufEnd && 87 BufPtr[0] == 'B' && 88 BufPtr[1] == 'C' && 89 BufPtr[2] == 0xc0 && 90 BufPtr[3] == 0xde; 91 } 92 93 /// isBitcode - Return true if the given bytes are the magic bytes for 94 /// LLVM IR bitcode, either with or without a wrapper. 95 /// isBitcode(const unsigned char * BufPtr,const unsigned char * BufEnd)96 static bool inline isBitcode(const unsigned char *BufPtr, 97 const unsigned char *BufEnd) { 98 return isBitcodeWrapper(BufPtr, BufEnd) || 99 isRawBitcode(BufPtr, BufEnd); 100 } 101 102 /// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special 103 /// header for padding or other reasons. The format of this header is: 104 /// 105 /// struct bc_header { 106 /// uint32_t Magic; // 0x0B17C0DE 107 /// uint32_t Version; // Version, currently always 0. 108 /// uint32_t BitcodeOffset; // Offset to traditional bitcode file. 109 /// uint32_t BitcodeSize; // Size of traditional bitcode file. 110 /// ... potentially other gunk ... 111 /// }; 112 /// 113 /// This function is called when we find a file with a matching magic number. 114 /// In this case, skip down to the subsection of the file that is actually a 115 /// BC file. SkipBitcodeWrapperHeader(unsigned char * & BufPtr,unsigned char * & BufEnd)116 static inline bool SkipBitcodeWrapperHeader(unsigned char *&BufPtr, 117 unsigned char *&BufEnd) { 118 enum { 119 KnownHeaderSize = 4*4, // Size of header we read. 120 OffsetField = 2*4, // Offset in bytes to Offset field. 121 SizeField = 3*4 // Offset in bytes to Size field. 122 }; 123 124 // Must contain the header! 125 if (BufEnd-BufPtr < KnownHeaderSize) return true; 126 127 unsigned Offset = ( BufPtr[OffsetField ] | 128 (BufPtr[OffsetField+1] << 8) | 129 (BufPtr[OffsetField+2] << 16) | 130 (BufPtr[OffsetField+3] << 24)); 131 unsigned Size = ( BufPtr[SizeField ] | 132 (BufPtr[SizeField +1] << 8) | 133 (BufPtr[SizeField +2] << 16) | 134 (BufPtr[SizeField +3] << 24)); 135 136 // Verify that Offset+Size fits in the file. 137 if (Offset+Size > unsigned(BufEnd-BufPtr)) 138 return true; 139 BufPtr += Offset; 140 BufEnd = BufPtr+Size; 141 return false; 142 } 143 } // End llvm namespace 144 145 #endif 146