'Create a PassManagerBuilder.
Note: a PassManagerBuilder seems good only for one use, so you
should call this method each time you want to populate a module
or function pass manager.  Otherwise some optimizations will be
missed...'

def _pass_manager_builder(self):

    pmb = lp.create_pass_manager_builder(opt=config.OPT, loop_vectorize=config.LOOP_VECTORIZE)
    return pmb
