Enable PT operators running with {cpu, gpu} * {forward, backward} (#22416)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22416
This diff tests the combination of cpu/gpu and forward/backward path for PT add operator.
Reviewed By: hl475
Differential Revision: D15770792
fbshipit-source-id: 38cc648361d2501d774db407f988c3cb5115b2ae
