Please forgive my ignorance, but how would this be useful? I am not familiar with compilers or what having bindings in Python to a compiler would help.
You could, for example, write a compiler in Python that generated native code (or LLVM bitcode to be passed to llc or whatever) via the LLVM API. Writing a compiler in Python vs. C/C++ would be a lot easier in a number of ways.
I'm not aware of any "production grade" compilers that do this, but no hard reason why not, I guess. Seems like it'd be nice for prototyping etc. if nothing else.
Final in the sense that hopefully we won't need a fourth one. It should provide the best performance (since the IR is not re-encoded in Python) and I've tried to make it flexible and future proof. llvmlite currently only supports LLVM 3.8, while I quickly tested llvmcpy with 3.4, 3.8 and 3.9 and works flawlessly.
It looks to be a less complete solution, since it only relies on the LLVM C API which is incomplete. llvmlite digs into the C++ API as well, so while it has more work to do to keep up with changes in LLVM, it's more more feature-complete
The LLVM-C API is quite powerful, and I'm planning to upstream some patch to expose additional stuff.
On the other hand, llvmlite doesn't even parse existing IR, it's basically write-only. Plus, representing the IR in Python makes it less memory efficient than using the native representation.
