pan/bi: Use nir_opt_idiv_const

Mitigates some of the hurt from idiv lowering.

total instructions in shared programs: 2734512 -> 2734269 (<.01%)
instructions in affected programs: 10419 -> 10176 (-2.33%)
helped: 11
HURT: 4
helped stats (abs) min: 9.0 max: 49.0 x̄: 22.45 x̃: 19
helped stats (rel) min: 1.84% max: 7.50% x̄: 3.65% x̃: 3.30%
HURT stats (abs)   min: 1.0 max: 1.0 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.14% max: 0.14% x̄: 0.14% x̃: 0.14%
95% mean confidence interval for instructions value: -25.34 -7.06
95% mean confidence interval for instructions %-change: -3.91% -1.37%
Instructions are helped.

total cycles in shared programs: 140629.05 -> 140628.61 (<.01%)
cycles in affected programs: 25.12 -> 24.69 (-1.74%)
helped: 3
HURT: 0
helped stats (abs) min: 0.0625 max: 0.3125 x̄: 0.15 x̃: 0
helped stats (rel) min: 0.82% max: 3.17% x̄: 1.60% x̃: 0.82%

total cvt in shared programs: 14826.25 -> 14819.52 (-0.05%)
cvt in affected programs: 189.64 -> 182.91 (-3.55%)
helped: 42
HURT: 0
helped stats (abs) min: 0.046875 max: 1.015625 x̄: 0.16 x̃: 0
helped stats (rel) min: 0.74% max: 11.76% x̄: 3.73% x̃: 2.82%
95% mean confidence interval for cvt value: -0.23 -0.09
95% mean confidence interval for cvt %-change: -4.65% -2.82%
Cvt are helped.

total sfu in shared programs: 8601.81 -> 8613.56 (0.14%)
sfu in affected programs: 85.62 -> 97.38 (13.72%)
helped: 0
HURT: 41
HURT stats (abs)   min: 0.0625 max: 1.25 x̄: 0.29 x̃: 0
HURT stats (rel)   min: 3.45% max: 33.33% x̄: 15.48% x̃: 16.67%
95% mean confidence interval for sfu value: 0.21 0.36
95% mean confidence interval for sfu %-change: 13.28% 17.69%
Sfu are HURT.

total quadwords in shared programs: 1479736 -> 1479616 (<.01%)
quadwords in affected programs: 3392 -> 3272 (-3.54%)
helped: 8
HURT: 0
helped stats (abs) min: 8.0 max: 24.0 x̄: 15.00 x̃: 16
helped stats (rel) min: 1.54% max: 4.62% x̄: 3.57% x̃: 3.71%
95% mean confidence interval for quadwords value: -20.58 -9.42
95% mean confidence interval for quadwords %-change: -4.39% -2.75%
Quadwords are helped.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17266>

src/panfrost/bifrost/bifrost_compile.c

@@ -4503,6 +4503,7 @@ bi_optimize_nir(nir_shader *nir, unsigned gpu_id, bool is_blend)
         nir_lower_idiv_options idiv_options = {
                 .allow_fp16 = true,
         };
+        NIR_PASS(progress, nir, nir_opt_idiv_const, 8);
         NIR_PASS(progress, nir, nir_lower_idiv, &idiv_options);
 
         NIR_PASS(progress, nir, nir_lower_tex, &lower_tex_options);