Good to hear!

I deleted _th_get_device, but it used to exist.
MM backward should end up calling one of these: https://github.com/pytorch/pytorch/blob/ba6c49cb9c516bb8c18984113f8c6c5f4c4556f6/tools/autograd/derivatives.yaml#L498-L500 16

Not quite sure what LSTMFusedBackward is, we have a lot of code generation as you noted.