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_3_2_H 15 #define LLVM_BITCODE_3_2_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 } // End llvm namespace 27 28 namespace llvm_3_2 { 29 /// getLazyBitcodeModule - 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 llvm::Module *getLazyBitcodeModule(llvm::MemoryBuffer *Buffer, 35 llvm::LLVMContext& Context, 36 std::string *ErrMsg = 0); 37 38 /// getBitcodeTargetTriple - Read the header of the specified bitcode 39 /// buffer and extract just the triple information. If successful, 40 /// this returns a string and *does not* take ownership 41 /// of 'buffer'. On error, this returns "", and fills in *ErrMsg 42 /// if ErrMsg is non-null. 43 std::string getBitcodeTargetTriple(llvm::MemoryBuffer *Buffer, 44 llvm::LLVMContext& Context, 45 std::string *ErrMsg = 0); 46 47 /// ParseBitcodeFile - Read the specified bitcode file, returning the module. 48 /// If an error occurs, this returns null and fills in *ErrMsg if it is 49 /// non-null. This method *never* takes ownership of Buffer. 50 llvm::Module *ParseBitcodeFile(llvm::MemoryBuffer *Buffer, llvm::LLVMContext& Context, 51 std::string *ErrMsg = 0); 52 53 /// WriteBitcodeToFile - Write the specified module to the specified 54 /// raw output stream. For streams where it matters, the given stream 55 /// should be in "binary" mode. 56 void WriteBitcodeToFile(const llvm::Module *M, llvm::raw_ostream &Out); 57 58 /// createBitcodeWriterPass - Create and return a pass that writes the module 59 /// to the specified ostream. 60 llvm::ModulePass *createBitcodeWriterPass(llvm::raw_ostream &Str); 61 62 63 /// isBitcodeWrapper - Return true if the given bytes are the magic bytes 64 /// for an LLVM IR bitcode wrapper. 65 /// 66 static inline bool isBitcodeWrapper(const unsigned char *BufPtr, 67 const unsigned char *BufEnd) { 68 // See if you can find the hidden message in the magic bytes :-). 69 // (Hint: it's a little-endian encoding.) 70 return BufPtr != BufEnd && 71 BufPtr[0] == 0xDE && 72 BufPtr[1] == 0xC0 && 73 BufPtr[2] == 0x17 && 74 BufPtr[3] == 0x0B; 75 } 76 77 /// isRawBitcode - Return true if the given bytes are the magic bytes for 78 /// raw LLVM IR bitcode (without a wrapper). 79 /// 80 static inline bool isRawBitcode(const unsigned char *BufPtr, 81 const unsigned char *BufEnd) { 82 // These bytes sort of have a hidden message, but it's not in 83 // little-endian this time, and it's a little redundant. 84 return BufPtr != BufEnd && 85 BufPtr[0] == 'B' && 86 BufPtr[1] == 'C' && 87 BufPtr[2] == 0xc0 && 88 BufPtr[3] == 0xde; 89 } 90 91 /// isBitcode - Return true if the given bytes are the magic bytes for 92 /// LLVM IR bitcode, either with or without a wrapper. 93 /// 94 static bool inline isBitcode(const unsigned char *BufPtr, 95 const unsigned char *BufEnd) { 96 return isBitcodeWrapper(BufPtr, BufEnd) || 97 isRawBitcode(BufPtr, BufEnd); 98 } 99 100 /// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special 101 /// header for padding or other reasons. The format of this header is: 102 /// 103 /// struct bc_header { 104 /// uint32_t Magic; // 0x0B17C0DE 105 /// uint32_t Version; // Version, currently always 0. 106 /// uint32_t BitcodeOffset; // Offset to traditional bitcode file. 107 /// uint32_t BitcodeSize; // Size of traditional bitcode file. 108 /// ... potentially other gunk ... 109 /// }; 110 /// 111 /// This function is called when we find a file with a matching magic number. 112 /// In this case, skip down to the subsection of the file that is actually a 113 /// BC file. 114 static inline bool SkipBitcodeWrapperHeader(unsigned char *&BufPtr, 115 unsigned char *&BufEnd) { 116 enum { 117 KnownHeaderSize = 4*4, // Size of header we read. 118 OffsetField = 2*4, // Offset in bytes to Offset field. 119 SizeField = 3*4 // Offset in bytes to Size field. 120 }; 121 122 // Must contain the header! 123 if (BufEnd-BufPtr < KnownHeaderSize) return true; 124 125 unsigned Offset = ( BufPtr[OffsetField ] | 126 (BufPtr[OffsetField+1] << 8) | 127 (BufPtr[OffsetField+2] << 16) | 128 (BufPtr[OffsetField+3] << 24)); 129 unsigned Size = ( BufPtr[SizeField ] | 130 (BufPtr[SizeField +1] << 8) | 131 (BufPtr[SizeField +2] << 16) | 132 (BufPtr[SizeField +3] << 24)); 133 134 // Verify that Offset+Size fits in the file. 135 if (Offset+Size > unsigned(BufEnd-BufPtr)) 136 return true; 137 BufPtr += Offset; 138 BufEnd = BufPtr+Size; 139 return false; 140 } 141 } // End llvm_3_2 namespace 142 143 #endif 144
