1 //===-- llvm/Bitcode/ReaderWriter.h - Bitcode reader/writers ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This header defines interfaces to read and write LLVM bitcode files/streams.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_BITCODE_H
15 #define LLVM_BITCODE_H
24 class BitstreamWriter;
28 /// getBitcodeModuleProvider - Read the header of the specified bitcode buffer
29 /// and prepare for lazy deserialization of function bodies. If successful,
30 /// this takes ownership of 'buffer' and returns a non-null pointer. On
31 /// error, this returns null, *does not* take ownership of Buffer, and fills
32 /// in *ErrMsg with an error description if ErrMsg is non-null.
33 ModuleProvider *getBitcodeModuleProvider(MemoryBuffer *Buffer,
35 std::string *ErrMsg = 0);
37 /// ParseBitcodeFile - Read the specified bitcode file, returning the module.
38 /// If an error occurs, this returns null and fills in *ErrMsg if it is
39 /// non-null. This method *never* takes ownership of Buffer.
40 Module *ParseBitcodeFile(MemoryBuffer *Buffer, LLVMContext& Context,
41 std::string *ErrMsg = 0);
43 /// WriteBitcodeToFile - Write the specified module to the specified
44 /// raw output stream.
45 void WriteBitcodeToFile(const Module *M, raw_ostream &Out);
47 /// WriteBitcodeToStream - Write the specified module to the specified
48 /// raw output stream.
49 void WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream);
51 /// createBitcodeWriterPass - Create and return a pass that writes the module
52 /// to the specified ostream.
53 ModulePass *createBitcodeWriterPass(raw_ostream &Str);
56 /// isBitcodeWrapper - Return true if the given bytes are the magic bytes
57 /// for an LLVM IR bitcode wrapper.
59 static inline bool isBitcodeWrapper(const unsigned char *BufPtr,
60 const unsigned char *BufEnd) {
61 // See if you can find the hidden message in the magic bytes :-).
62 // (Hint: it's a little-endian encoding.)
63 return BufPtr != BufEnd &&
70 /// isRawBitcode - Return true if the given bytes are the magic bytes for
71 /// raw LLVM IR bitcode (without a wrapper).
73 static inline bool isRawBitcode(const unsigned char *BufPtr,
74 const unsigned char *BufEnd) {
75 // These bytes sort of have a hidden message, but it's not in
76 // little-endian this time, and it's a little redundant.
77 return BufPtr != BufEnd &&
84 /// isBitcode - Return true if the given bytes are the magic bytes for
85 /// LLVM IR bitcode, either with or without a wrapper.
87 static bool inline isBitcode(const unsigned char *BufPtr,
88 const unsigned char *BufEnd) {
89 return isBitcodeWrapper(BufPtr, BufEnd) ||
90 isRawBitcode(BufPtr, BufEnd);
93 /// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special
94 /// header for padding or other reasons. The format of this header is:
96 /// struct bc_header {
97 /// uint32_t Magic; // 0x0B17C0DE
98 /// uint32_t Version; // Version, currently always 0.
99 /// uint32_t BitcodeOffset; // Offset to traditional bitcode file.
100 /// uint32_t BitcodeSize; // Size of traditional bitcode file.
101 /// ... potentially other gunk ...
104 /// This function is called when we find a file with a matching magic number.
105 /// In this case, skip down to the subsection of the file that is actually a
107 static inline bool SkipBitcodeWrapperHeader(unsigned char *&BufPtr,
108 unsigned char *&BufEnd) {
110 KnownHeaderSize = 4*4, // Size of header we read.
111 OffsetField = 2*4, // Offset in bytes to Offset field.
112 SizeField = 3*4 // Offset in bytes to Size field.
115 // Must contain the header!
116 if (BufEnd-BufPtr < KnownHeaderSize) return true;
118 unsigned Offset = ( BufPtr[OffsetField ] |
119 (BufPtr[OffsetField+1] << 8) |
120 (BufPtr[OffsetField+2] << 16) |
121 (BufPtr[OffsetField+3] << 24));
122 unsigned Size = ( BufPtr[SizeField ] |
123 (BufPtr[SizeField +1] << 8) |
124 (BufPtr[SizeField +2] << 16) |
125 (BufPtr[SizeField +3] << 24));
127 // Verify that Offset+Size fits in the file.
128 if (Offset+Size > unsigned(BufEnd-BufPtr))
131 BufEnd = BufPtr+Size;
134 } // End llvm namespace