nir/constant_folding: Optimize txb with bias of constant zero to tex
v2: Fail gracefully when bias_idx < 0. See comment in the code for the
rationale. See also issue #5722.
All Haswell and newer Intel GPUs had similar results. (Ice Lake shown)
total instructions in shared programs:
19757733 ->
19753431 (-0.02%)
instructions in affected programs: 277248 -> 272946 (-1.55%)
helped: 1644
HURT: 1
helped stats (abs) min: 1 max: 16 x̄: 2.62 x̃: 2
helped stats (rel) min: 0.05% max: 11.11% x̄: 2.11% x̃: 1.61%
HURT stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel) min: 0.35% max: 0.35% x̄: 0.35% x̃: 0.35%
95% mean confidence interval for instructions value: -2.72 -2.51
95% mean confidence interval for instructions %-change: -2.19% -2.03%
Instructions are helped.
total cycles in shared programs:
938517439 ->
938384079 (-0.01%)
cycles in affected programs:
19548849 ->
19415489 (-0.68%)
helped: 1358
HURT: 269
helped stats (abs) min: 1 max: 2328 x̄: 133.01 x̃: 16
helped stats (rel) min: <.01% max: 41.12% x̄: 1.40% x̃: 0.48%
HURT stats (abs) min: 1 max: 1302 x̄: 175.70 x̃: 30
HURT stats (rel) min: <.01% max: 69.03% x̄: 6.24% x̃: 1.04%
95% mean confidence interval for cycles value: -99.14 -64.79
95% mean confidence interval for cycles %-change: -0.47% 0.19%
Inconclusive result (%-change mean confidence interval includes 0).
LOST: 21
GAINED: 32
All Ivy Bridge and older Intel GPUs had similar results. (Ivy Bridge shown)
total instructions in shared programs:
15302017 ->
15301485 (<.01%)
instructions in affected programs: 22565 -> 22033 (-2.36%)
helped: 168
HURT: 0
helped stats (abs) min: 1 max: 7 x̄: 3.17 x̃: 3
helped stats (rel) min: 0.04% max: 4.39% x̄: 3.05% x̃: 3.27%
95% mean confidence interval for instructions value: -3.45 -2.89
95% mean confidence interval for instructions %-change: -3.19% -2.91%
Instructions are helped.
total cycles in shared programs:
550119761 ->
549989147 (-0.02%)
cycles in affected programs:
12834251 ->
12703637 (-1.02%)
helped: 164
HURT: 0
helped stats (abs) min: 20 max: 4547 x̄: 796.43 x̃: 294
helped stats (rel) min: 0.23% max: 53.84% x̄: 2.05% x̃: 0.37%
95% mean confidence interval for cycles value: -942.62 -650.24
95% mean confidence interval for cycles %-change: -3.17% -0.94%
Cycles are helped.
fossil-db results:
Tiger Lake, Ice Lake, and Skylake had similar results. (Ice Lake shown)
Instructions in all programs:
142073649 ->
141307526 (-0.5%)
SENDs in all programs: 6876848 -> 6876778 (-0.0%)
Loops in all programs: 38283 -> 38283 (+0.0%)
Cycles in all programs:
8410049681 ->
8402902960 (-0.1%)
Spills in all programs: 190623 -> 190599 (-0.0%)
Fills in all programs: 297780 -> 297756 (-0.0%)
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> [v1]
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14025>