error when using _dynamo.optimize_ddp=True and _inductor.keep_output_stride=False together (#108235)
From talking to @wconstab, we agreed that because of the way DDPOptimizer is written, it is (sort of) incompatible with inductor's `keep_output_stride=False` optimizations (and will cause silent correctness problems if you use them ogether). Added an assertion.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108235
Approved by: https://github.com/wconstab
ghstack dependencies: #108081
