Separate gpu reduce functions (#17146)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17146
Separate gpu reduce functions
i-am-not-moving-c2-to-c10
Reviewed By: houseroad
Differential Revision: D14097564
fbshipit-source-id: a27de340997111a794b1d083c1673d4263afb9fb
