Support softmax with D == 0 (#29167)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29167
As titled.
This fix is crucial as multi_channel splitting would create history that has no items (i.e., D == 0), which leads to flow failure.
Test Plan:
Unittest
flow test:
before fix: f148783160
after fix: f149082299
buck test mode/dev-nosan caffe2/caffe2/python/operator_test:softmax_ops_test
Reviewed By: xianjiec
Differential Revision: D18296081
fbshipit-source-id: e0bb2dc2c4e5b465e213f31e5c5ced3a7e1fd574
