Add CostInferenceFunction for SplitOp (#63133)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63133
SplitOp is costly but missing cost inference function which hurts cost based balancing. Changes are:
(1) Addition of CostInferenceFunction for SplitOp
(2) Small fix in CostInferenceFunction for ConcatOp
Test Plan:
Added unit tests:
buck test //caffe2/caffe2/python/operator_test:split_op_cost_test
buck test //caffe2/caffe2/python/operator_test:concat_op_cost_test
Reviewed By: smacke
Differential Revision: D30247360
fbshipit-source-id: 989e962f3a981acc85b73aac3fb23e603b7d1591
