pytorch

67bb7b29 - Fix autodiff of nll_loss

Fix autodiff of nll_loss Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/16851 Differential Revision: D13995046 Pulled By: wanchaol fbshipit-source-id: 557c99f1d1825fa9b6031dd9fa8ba9b54205e8c4