intel/nir: Lower 8-bit scan/reduce ops to 16-bit
We can't really support these directly on any platform. May as well let
NIR lower them. The NIR lowering is potentially one more instruction
for scan/reduce ops thanks to not being able to do the B->W conversion
as part of SEL_EXEC. For imax/imin exclusive scan, it's yet another
instruction thanks to the extra imax/imin NIR has to insert to deal with
the fact that the first live channel will contain the identity value
which, when signed, will cast wrong. However, it does let us drop some
complexity from our back-end so it's probably worth it.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7482>
2 files changed
