问题
i've assumed that dumping a .bc file from a module was a trivial operation, but now, first time i have to actually do it from code, for the life of me i can't find one missing step in the process:
static void WriteModule ( const Module * M, BitstreamWriter & Stream )
http://llvm.org/docs/doxygen/html/BitcodeWriter_8cpp.html#a828cec7a8fed9d232556420efef7ae89
to write that module, first i need a BistreamWriter
BitstreamWriter::BitstreamWriter (SmallVectorImpl< char > &O)
http://llvm.org/docs/doxygen/html/classllvm_1_1BitstreamWriter.html
and for a BitstreamWriter i need a SmallVectorImpl. But, what next? Should i write the content of the SmallVectorImpl byte by byte on a file handler myself? is there a llvm api for this? do i need something else?
回答1:
The WriteModule function is static within lib/Bitcode/Writer/BitcodeWriter.cpp, which means it's not there for outside consumption (you can't even access it).
The same file has another function, however, called WriteBitcodeToFile, with this interface:
/// WriteBitcodeToFile - Write the specified module to the specified output
/// stream.
void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out);
I can't imagine a more convenient interface. The header file declaring it is ./include/llvm/Bitcode/ReaderWriter.h, by the way.
回答2:
I use following code :
std::error_code EC;
llvm::raw_fd_ostream OS("module", EC, llvm::sys::fs::F_None);
WriteBitcodeToFile(pBiFModule, OS);
OS.flush();
and then disassemble using llvm-dis.
来源：https://stackoverflow.com/questions/13903686/writing-module-to-bc-bitcode-file