radv: do not lower UBO/SSBO access to offsets

Use nir_lower_explicit_io instead of lowering to offsets. Extra
(useless) additions are removed by lowering load_vulkan_descriptor
to vec2(src.x, 0).

fossils-db (Navi):
Totals from 18236 (13.21% of 138013) affected shaders:
SGPRs: 1172766 -> 1168278 (-0.38%); split: -0.89%, +0.50%
VGPRs: 940156 -> 952232 (+1.28%); split: -0.08%, +1.37%
SpillSGPRs: 30286 -> 31109 (+2.72%); split: -0.78%, +3.50%
SpillVGPRs: 1893 -> 1909 (+0.85%)
CodeSize: 87910396 -> 88113592 (+0.23%); split: -0.35%, +0.58%
Scratch: 819200 -> 823296 (+0.50%)
MaxWaves: 205535 -> 202102 (-1.67%); split: +0.05%, -1.72%
Instrs: 17052527 -> 17113484 (+0.36%); split: -0.32%, +0.67%
Cycles: 670794876 -> 669084540 (-0.25%); split: -0.38%, +0.13%
VMEM: 5274728 -> 5388556 (+2.16%); split: +3.10%, -0.94%
SMEM: 1196146 -> 1165850 (-2.53%); split: +2.06%, -4.60%
VClause: 381463 -> 399217 (+4.65%); split: -1.08%, +5.73%
SClause: 666216 -> 631135 (-5.27%); split: -5.44%, +0.18%
Copies: 1292720 -> 1289318 (-0.26%); split: -1.28%, +1.01%
Branches: 467336 -> 473028 (+1.22%); split: -0.67%, +1.89%
PreSGPRs: 766459 -> 772175 (+0.75%); split: -0.53%, +1.28%
PreVGPRs: 819746 -> 825327 (+0.68%); split: -0.05%, +0.73%

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6202>
3 files changed