137 lines
5.2 KiB
C++
137 lines
5.2 KiB
C++
//===-- llvm/Bitcode/ReaderWriter.h - Bitcode reader/writers ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This header defines interfaces to read and write LLVM bitcode files/streams.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_BITCODE_H
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#define LLVM_BITCODE_H
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#include <string>
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namespace llvm {
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class Module;
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class ModuleProvider;
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class MemoryBuffer;
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class ModulePass;
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class BitstreamWriter;
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class LLVMContext;
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class raw_ostream;
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/// getBitcodeModuleProvider - Read the header of the specified bitcode buffer
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/// and prepare for lazy deserialization of function bodies. If successful,
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/// this takes ownership of 'buffer' and returns a non-null pointer. On
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/// error, this returns null, *does not* take ownership of Buffer, and fills
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/// in *ErrMsg with an error description if ErrMsg is non-null.
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ModuleProvider *getBitcodeModuleProvider(MemoryBuffer *Buffer,
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LLVMContext& Context,
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std::string *ErrMsg = 0);
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/// ParseBitcodeFile - Read the specified bitcode file, returning the module.
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/// If an error occurs, this returns null and fills in *ErrMsg if it is
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/// non-null. This method *never* takes ownership of Buffer.
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Module *ParseBitcodeFile(MemoryBuffer *Buffer, LLVMContext& Context,
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std::string *ErrMsg = 0);
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/// WriteBitcodeToFile - Write the specified module to the specified
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/// raw output stream.
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void WriteBitcodeToFile(const Module *M, raw_ostream &Out);
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/// WriteBitcodeToStream - Write the specified module to the specified
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/// raw output stream.
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void WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream);
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/// createBitcodeWriterPass - Create and return a pass that writes the module
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/// to the specified ostream.
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ModulePass *createBitcodeWriterPass(raw_ostream &Str);
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/// isBitcodeWrapper - Return true if the given bytes are the magic bytes
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/// for an LLVM IR bitcode wrapper.
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///
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static inline bool isBitcodeWrapper(const unsigned char *BufPtr,
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const unsigned char *BufEnd) {
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// See if you can find the hidden message in the magic bytes :-).
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// (Hint: it's a little-endian encoding.)
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return BufPtr != BufEnd &&
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BufPtr[0] == 0xDE &&
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BufPtr[1] == 0xC0 &&
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BufPtr[2] == 0x17 &&
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BufPtr[3] == 0x0B;
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}
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/// isRawBitcode - Return true if the given bytes are the magic bytes for
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/// raw LLVM IR bitcode (without a wrapper).
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///
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static inline bool isRawBitcode(const unsigned char *BufPtr,
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const unsigned char *BufEnd) {
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// These bytes sort of have a hidden message, but it's not in
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// little-endian this time, and it's a little redundant.
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return BufPtr != BufEnd &&
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BufPtr[0] == 'B' &&
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BufPtr[1] == 'C' &&
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BufPtr[2] == 0xc0 &&
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BufPtr[3] == 0xde;
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}
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/// isBitcode - Return true if the given bytes are the magic bytes for
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/// LLVM IR bitcode, either with or without a wrapper.
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///
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static bool inline isBitcode(const unsigned char *BufPtr,
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const unsigned char *BufEnd) {
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return isBitcodeWrapper(BufPtr, BufEnd) ||
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isRawBitcode(BufPtr, BufEnd);
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}
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/// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special
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/// header for padding or other reasons. The format of this header is:
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///
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/// struct bc_header {
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/// uint32_t Magic; // 0x0B17C0DE
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/// uint32_t Version; // Version, currently always 0.
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/// uint32_t BitcodeOffset; // Offset to traditional bitcode file.
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/// uint32_t BitcodeSize; // Size of traditional bitcode file.
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/// ... potentially other gunk ...
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/// };
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///
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/// This function is called when we find a file with a matching magic number.
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/// In this case, skip down to the subsection of the file that is actually a
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/// BC file.
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static inline bool SkipBitcodeWrapperHeader(unsigned char *&BufPtr,
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unsigned char *&BufEnd) {
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enum {
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KnownHeaderSize = 4*4, // Size of header we read.
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OffsetField = 2*4, // Offset in bytes to Offset field.
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SizeField = 3*4 // Offset in bytes to Size field.
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};
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// Must contain the header!
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if (BufEnd-BufPtr < KnownHeaderSize) return true;
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unsigned Offset = ( BufPtr[OffsetField ] |
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(BufPtr[OffsetField+1] << 8) |
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(BufPtr[OffsetField+2] << 16) |
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(BufPtr[OffsetField+3] << 24));
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unsigned Size = ( BufPtr[SizeField ] |
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(BufPtr[SizeField +1] << 8) |
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(BufPtr[SizeField +2] << 16) |
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(BufPtr[SizeField +3] << 24));
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// Verify that Offset+Size fits in the file.
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if (Offset+Size > unsigned(BufEnd-BufPtr))
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return true;
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BufPtr += Offset;
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BufEnd = BufPtr+Size;
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return false;
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}
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} // End llvm namespace
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#endif
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