b9a0c8dc6d
this is the lowering from NAK, fixed up for common code. the existing code is used for boolean scan/reduce. I make no guarantee that this works for subgroup sizes other than 32. Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io> Reviewed-by: Daniel Schürmann <daniel@schuermann.dev> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28993>