GitLab

* Update cuda_column_data.hpp

* Update cuda_metadata.hpp

* Update cuda_objective_function.hpp

* Update cuda_row_data.hpp

* Update cuda_regression_objective.hpp

* add huber regression for cuda_exp

* renew tree output on GPU

add test cases for regression objectives

* remove useless changes

* add white space

* fix test_regression

* add (l1) regression objective for cuda_exp

* remove RenewTreeOutputCUDA from CUDARegressionL2loss

* remove mutable and use CUDAVector

* remove white spaces

* remove TODO and document in (#5459)

* add (l2) regression objective for cuda_exp

* fix lint errors

* correct time tag