In some case the pickling leads to miss-reconstruction of `-1` with differences like ``` - loat px = -floor((-o_x + src_coords[p_src][0])/h_x) + (-o_x + src_coords[p_src][0])/h_x; + loat px = (-1)*floor((-o_x + src_coords[p_src][0])/h_x) + (-o_x + src_coords[p_src][0])/h_x; ``` In [`test_pickle.py::TestOperator::test_usave_sampled`](https://github.com/devitocodes/devito/blob/a7c34461e1152975d67df2f8eb3e959cbf02c752/tests/test_pickle.py#L797)