llevm is an erlang wrapper to the C API functions of llvm. The documentation of the functions can be found at the official llvm website. Unfortunately the documentation of the C functions seem to be very sparse, so when looking for what functions do one should try to find the corresponding C++ class function and read the documentation for it instead.
For examples on how to use llevm see the testcases, especially
contain lots of basics in how to generate llvm code and use the JIT
execution engine from Erlang.
Most functions are converted to erlang and hopefully work as well :)
There is a list of which functions are not as yet converted in
api_gen/llvm_api.hrl. The functions are listed in the LIMIT macro.
You should only have to run
./configure && make
to compile llevm. Make sure that the correct llvm version is in the path.
Some possible issues when compiling are:
- The erlang vm and llvm has to have the same arch (i.e. 64 vs 32 bit)
- You have to have the correct version of llvm. As of this writing that is 2.9. If you need another version you have to regenerate all the erlang and nif files.
Generating a new llevm
If you are not happy with the generated API you can regenerate it to suite your needs. To do this you have to have doxygen in your path then run:
./configure && (cd api_gen && make)
include/llevm.hrl should be
regerated. The code which generated the llevm interface is in the api_gen
folder and divided into the different files that they generate.
llevm comes with a set of test which tests that everything works as it should. To run the tests type:
The tests are very basic and are more there to provide examples than to test the actual interface. So just because they pass don't trust that llevm does what it should :)
It is possible to enable lots of debug printouts in
Just search for printf and uncomment those lines and then regenerate llevm.
It is also helpful to use gdb to step through execution, there are some
example commands in
os_lathund to show how I do it on my mac.