pytorch

e299393f - [Gradient Compression] Provide 2 default C++ comm hooks (#46701)

[Gradient Compression] Provide 2 default C++ comm hooks (#46701) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/46701 Provide 2 built-in implementations of C++ comm hook. Original PR issue: C++ DDP Communication Hook https://github.com/pytorch/pytorch/issues/46348 ghstack-source-id: 115319061 Test Plan: waitforbuildbot Reviewed By: pritamdamania87 Differential Revision: D24382504 fbshipit-source-id: 1c1ef56620f91ab37a1707c5589f1d0eb4455bb3