Optimize SoftmaxOp on CPU (#18635)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18635
Optimize SoftmaxOp on CPU
Reviewed By: houseroad
Differential Revision: D14689516
fbshipit-source-id: d2dcee2476d1a3a21f428e99bce9835f1d229d64
