panfrost: Push twice as many uniforms

The limit for Bifrost is twice as high as previously thought -- the limit is 64
*slots* of FAU, not 64 words. Each slot is 2 words. We can push twice as much,
saving a considerable number of cycles in some cases.

total instructions in shared programs: 2454260 -> 2431502 (-0.93%)
instructions in affected programs: 845176 -> 822418 (-2.69%)
helped: 3376
HURT: 304
helped stats (abs) min: 1.0 max: 60.0 x̄: 7.92 x̃: 6
helped stats (rel) min: 0.13% max: 45.45% x̄: 4.60% x̃: 4.11%
HURT stats (abs)   min: 1.0 max: 60.0 x̄: 13.06 x̃: 8
HURT stats (rel)   min: 0.16% max: 35.09% x̄: 7.58% x̃: 6.52%
95% mean confidence interval for instructions value: -6.50 -5.87
95% mean confidence interval for instructions %-change: -3.75% -3.43%
Instructions are helped.

total tuples in shared programs: 1963383 -> 1951560 (-0.60%)
tuples in affected programs: 638622 -> 626799 (-1.85%)
helped: 2959
HURT: 573
helped stats (abs) min: 1.0 max: 54.0 x̄: 5.61 x̃: 4
helped stats (rel) min: 0.15% max: 28.57% x̄: 3.61% x̃: 3.12%
HURT stats (abs)   min: 1.0 max: 50.0 x̄: 8.35 x̃: 6
HURT stats (rel)   min: 0.25% max: 27.34% x̄: 6.24% x̃: 4.92%
95% mean confidence interval for tuples value: -3.61 -3.08
95% mean confidence interval for tuples %-change: -2.18% -1.85%
Tuples are helped.

total clauses in shared programs: 387817 -> 365111 (-5.85%)
clauses in affected programs: 135527 -> 112821 (-16.75%)
helped: 3489
HURT: 25
helped stats (abs) min: 1.0 max: 43.0 x̄: 6.52 x̃: 5
helped stats (rel) min: 0.82% max: 58.33% x̄: 17.48% x̃: 15.87%
HURT stats (abs)   min: 1.0 max: 3.0 x̄: 1.56 x̃: 1
HURT stats (rel)   min: 2.94% max: 11.11% x̄: 6.87% x̃: 6.67%
95% mean confidence interval for clauses value: -6.67 -6.26
95% mean confidence interval for clauses %-change: -17.65% -16.96%
Clauses are helped.

total cycles in shared programs: 201842.21 -> 168754.04 (-16.39%)
cycles in affected programs: 84035.50 -> 50947.33 (-39.37%)
helped: 3547
HURT: 136
helped stats (abs) min: 0.041665999999999315 max: 54.0 x̄: 9.33 x̃: 8
helped stats (rel) min: 0.17% max: 80.77% x̄: 36.10% x̃: 36.84%
HURT stats (abs)   min: 0.041665999999999315 max: 1.0 x̄: 0.12 x̃: 0
HURT stats (rel)   min: 0.18% max: 12.24% x̄: 1.18% x̃: 0.61%
95% mean confidence interval for cycles value: -9.26 -8.71
95% mean confidence interval for cycles %-change: -35.34% -34.11%
Cycles are helped.

total arith in shared programs: 74918.46 -> 75022.62 (0.14%)
arith in affected programs: 22471.04 -> 22575.21 (0.46%)
helped: 1571
HURT: 1492
helped stats (abs) min: 0.041665999999999315 max: 1.125 x̄: 0.17 x̃: 0
helped stats (rel) min: 0.17% max: 40.00% x̄: 2.50% x̃: 1.96%
HURT stats (abs)   min: 0.041665999999999315 max: 2.375 x̄: 0.25 x̃: 0
HURT stats (rel)   min: 0.16% max: 100.00% x̄: 5.35% x̃: 2.37%
95% mean confidence interval for arith value: 0.02 0.05
95% mean confidence interval for arith %-change: 1.08% 1.56%
Arith are HURT.

total ldst in shared programs: 174812 -> 137889 (-21.12%)
ldst in affected programs: 81319 -> 44396 (-45.41%)
helped: 3722
HURT: 0
helped stats (abs) min: 1.0 max: 62.0 x̄: 9.92 x̃: 8
helped stats (rel) min: 1.82% max: 100.00% x̄: 47.18% x̃: 43.75%
95% mean confidence interval for ldst value: -10.20 -9.64
95% mean confidence interval for ldst %-change: -47.97% -46.39%
Ldst are helped.

total quadwords in shared programs: 1757124 -> 1714130 (-2.45%)
quadwords in affected programs: 584065 -> 541071 (-7.36%)
helped: 3474
HURT: 173
helped stats (abs) min: 1.0 max: 90.0 x̄: 12.66 x̃: 9
helped stats (rel) min: 0.26% max: 34.18% x̄: 8.78% x̃: 8.33%
HURT stats (abs)   min: 1.0 max: 26.0 x̄: 5.76 x̃: 4
HURT stats (rel)   min: 0.45% max: 20.66% x̄: 4.48% x̃: 2.63%
95% mean confidence interval for quadwords value: -12.21 -11.37
95% mean confidence interval for quadwords %-change: -8.36% -7.95%
Quadwords are helped.

total threads in shared programs: 52898 -> 53142 (0.46%)
threads in affected programs: 262 -> 506 (93.13%)
helped: 250
HURT: 6
helped stats (abs) min: 1.0 max: 1.0 x̄: 1.00 x̃: 1
helped stats (rel) min: 100.00% max: 100.00% x̄: 100.00% x̃: 100.00%
HURT stats (abs)   min: 1.0 max: 1.0 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 50.00% max: 50.00% x̄: 50.00% x̃: 50.00%
95% mean confidence interval for threads value: 0.92 0.99
95% mean confidence interval for threads %-change: 93.69% 99.28%
Threads are helped.

total spills in shared programs: 161 -> 107 (-33.54%)
spills in affected programs: 54 -> 0
helped: 27
HURT: 0

total fills in shared programs: 1386 -> 796 (-42.57%)
fills in affected programs: 590 -> 0
helped: 27
HURT: 0

Fixes: d4dccea0ba ("panfrost: Add UBO push data structure")
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15239>

src/panfrost/util/pan_ir.h

@@ -130,11 +130,17 @@ struct panfrost_sysvals {
         unsigned sysval_count;
 };
 
-/* Technically Midgard could go up to 92 in a pathological case but we don't
- * take advantage of that. Likewise Bifrost's FAU encoding can address 128
- * words but actual implementations (G72, G76) are capped at 64 */
-
-#define PAN_MAX_PUSH 64
+/* Architecturally, Bifrost/Valhall can address 128 FAU slots of 64-bits each.
+ * In practice, the maximum number of FAU slots is limited by implementation.
+ * All known Bifrost and Valhall devices limit to 64 FAU slots. Therefore the
+ * maximum number of 32-bit words is 128, since there are 2 words per FAU slot.
+ *
+ * Midgard can push at most 92 words, so this bound suffices. The Midgard
+ * compiler pushes less than this, as Midgard uses register-mapped uniforms
+ * instead of FAU, preventing large numbers of uniforms to be pushed for
+ * nontrivial programs.
+ */
+#define PAN_MAX_PUSH 128
 
 /* Architectural invariants (Midgard and Bifrost): UBO must be <= 2^16 bytes so
  * an offset to a word must be < 2^16. There are less than 2^8 UBOs */