Automatic fallback to cpu

Feature suggestion: enable automatic fallback for layers where mps implementations are not available (yet).

Case in point: I load a random pytorch model, do“mps”) and upon running the model get an error such as:

‘aten::_slow_conv2d_forward’ is only available for these backends: SparseCPU … …


We added such a feature in master already!
It will be in the next nightly build tomorrow (Saturday May 20th) and is already available if you build from source!