I'm using the LLVM C++ API to create code on-the-fly for execution. This works fine. But what if I want to save this code to disk, quit, relaunch my app at some later time, reload the previously generated code off disk, and execute it?
How can I do that? Can somebody point me to some documentation or examples? Thanks.
- Paul
"Paul J. Lucas" <paul@lucasmail.org> writes:
I'm using the LLVM C++ API to create code on-the-fly for execution.
This works fine. But what if I want to save this code to disk, quit,
relaunch my app at some later time, reload the previously generated
code off disk, and execute it?How can I do that? Can somebody point me to some documentation or
examples? Thanks.
For starters, you need the BitWriter and BitReader libraries. See the
lli tool (under tools/lli/lli.cpp) for an example on how to use the
BitReader and llc or llvm-as to see how to use the BitWriter.
It is quite easy. The critical part for saving is:
std::string errorInfo;
llvm::raw_fd_ostream f("mybitcode.bc", errorInfo, raw_fd_ostream::F_Binary);
WriteBitcodeToFile(M, f);
where M is a llvm::Module*.
For reading:
LLVMContext Context;
SMDiagnostic Err;
Module *M = ParseIRFile("mybitcode.bc", Err, Context);
You need to add the dependencies to your build, header files, etc. See
the llvm tools mentioned above.