LGTM, but some description of what is tested would be useful. I would not expect people to search for the initial commit, find D132063 in the comment, and hope that Phabricator is still up.
Could you add a comment on what the point of running on sorted data over random data is? Isn't it pointwise anyway?
Some description of what is being tested would be useful. min_index_select_u32_u32_start_0 isn't very descriptive.