Allow single node fusion for nvfuser (#70000)
Summary:
Setting `PYTORCH_NVFUSER_ONE_OP_FUSION=1` will take all nodes nvFuser support, instead of waiting for fusion opportunity.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70000
Reviewed By: samdow
Differential Revision: D33292195
Pulled By: davidberard98
fbshipit-source-id: 8ed5ce5e82fbb6737e8ab5ce4223b038eaf47756
