Sometimes one source can be a larger register than the other, especially
since opt_register_coalesce can sometimes coalesce those sources into
larger registers.
Copy the smaller of mlen and ex_mlen. It's less copying.
shader-db and fossil-db on Alchemist show 47 shaders affected with
small 1-2 instruction improvements each, and no regressions.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27876>
This doesn't help very much now. A later commit adds a NIR optimization
pass, tentatively called nir_opt_uniform_subgroup, that converts many
kinds of subgroup operations to things involving
bitCount(ballot(true)). This commit makes a huge difference in the
results of that later commit.
No shader-db changes on any Intel platform.
Fossil-db results:
All Intel platforms had similar results. (Ice Lake shown)
Totals:
Instrs: 165558033 -> 165557519 (-0.00%)
Cycles: 15156188362 -> 15156178922 (-0.00%); split: -0.00%, +0.00%
Totals from 299 (0.05% of 656117) affected shaders:
Instrs: 88293 -> 87779 (-0.58%)
Cycles: 3709498 -> 3700058 (-0.25%); split: -0.28%, +0.03%
v2: Rebase on splitting ELK from BRW. Remove devinfo->ver >= 8 check.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27044>
