m>.
This is because to date Python Autograd functions cannot be compiled
by Pytorch’s JIT compiler, but C++ Autograd functions can. Compiling the C++ extension is performed at runtime
in order to simplify packaging and distribution (only a single .cpp source file is distributed).
This requires the user to have an appropriate C++ compiler, so a Python implemention is provided as fallback.</p>
<p>Because of this, as long as <cite>BREVITAS_JIT=0</cite> (which it is by default), the C++ backend is not loaded.