'Internal: run function-level optimizations inside *ll_module*.'

def _optimize_functions(self, ll_module):

    ll_module.data_layout = self._codegen._data_layout
    with self._codegen._function_pass_manager(ll_module) as fpm:
        for func in ll_module.functions:
            fpm.initialize()
            fpm.run(func)
            fpm.finalize()
