Mesa (master): nir/algebraic: Add some half packing optimizations for pack_half_2x16_split

[GitLab Mirror]

Module: Mesa
Branch: master
Commit: bc0bbb8f0b45049e597d7d585999ae4954266347
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=bc0bbb8f0b45049e597d7d585999ae4954266347

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Thu Apr  2 12:20:57 2020 -0700

nir/algebraic: Add some half packing optimizations for pack_half_2x16_split

Like 1f72857739b ("nir/algebraic: add some half packing optimizations"),
but for the pack_half_2x16_split variant.

The shader helped for spills and fills is the big compute shader in
Bioshock Infinite.

Tiger Lake
total instructions in shared programs: 21834539 -> 21833218 (<.01%)
instructions in affected programs: 60119 -> 58798 (-2.20%)
helped: 105
HURT: 0
helped stats (abs) min: 5 max: 50 x̄: 12.58 x̃: 9
helped stats (rel) min: 0.86% max: 26.46% x̄: 2.58% x̃: 1.70%
95% mean confidence interval for instructions value: -14.35 -10.81
95% mean confidence interval for instructions %-change: -3.20% -1.97%
Instructions are helped.

total cycles in shared programs: 506215169 -> 506180109 (<.01%)
cycles in affected programs: 1445088 -> 1410028 (-2.43%)
helped: 97
HURT: 8
helped stats (abs) min: 1 max: 16882 x̄: 387.76 x̃: 26
helped stats (rel) min: 0.05% max: 18.31% x̄: 1.77% x̃: 1.34%
HURT stats (abs)   min: 21 max: 635 x̄: 319.12 x̃: 212
HURT stats (rel)   min: 0.39% max: 20.08% x̄: 8.96% x̃: 4.46%
95% mean confidence interval for cycles value: -782.96 115.15
95% mean confidence interval for cycles %-change: -1.74% -0.16%
Inconclusive result (value mean confidence interval includes 0).

Ice Lake, Skylake, and Broadwell had similar results. (Ice Lake shown)
total instructions in shared programs: 19962974 -> 19961317 (<.01%)
instructions in affected programs: 63471 -> 61814 (-2.61%)
helped: 105
HURT: 0
helped stats (abs) min: 6 max: 82 x̄: 15.78 x̃: 11
helped stats (rel) min: 1.11% max: 28.65% x̄: 3.17% x̃: 2.16%
95% mean confidence interval for instructions value: -18.38 -13.18
95% mean confidence interval for instructions %-change: -3.86% -2.48%
Instructions are helped.

total cycles in shared programs: 498908953 -> 498863755 (<.01%)
cycles in affected programs: 1566998 -> 1521800 (-2.88%)
helped: 89
HURT: 15
helped stats (abs) min: 2 max: 17502 x̄: 532.19 x̃: 69
helped stats (rel) min: 0.07% max: 18.54% x̄: 4.71% x̃: 3.12%
HURT stats (abs)   min: 3 max: 661 x̄: 144.47 x̃: 16
HURT stats (rel)   min: 0.14% max: 20.57% x̄: 4.29% x̃: 0.30%
95% mean confidence interval for cycles value: -903.93 34.74
95% mean confidence interval for cycles %-change: -4.50% -2.32%
Inconclusive result (value mean confidence interval includes 0).

total spills in shared programs: 8776 -> 8774 (-0.02%)
spills in affected programs: 25 -> 23 (-8.00%)
helped: 1
HURT: 0

total fills in shared programs: 9500 -> 9496 (-0.04%)
fills in affected programs: 46 -> 42 (-8.70%)
helped: 1
HURT: 0

Haswell
total instructions in shared programs: 16229912 -> 16228399 (<.01%)
instructions in affected programs: 61257 -> 59744 (-2.47%)
helped: 105
HURT: 0
helped stats (abs) min: 6 max: 51 x̄: 14.41 x̃: 11
helped stats (rel) min: 0.77% max: 28.65% x̄: 3.08% x̃: 2.15%
95% mean confidence interval for instructions value: -16.14 -12.68
95% mean confidence interval for instructions %-change: -3.77% -2.40%
Instructions are helped.

total cycles in shared programs: 538654481 -> 538613967 (<.01%)
cycles in affected programs: 1448966 -> 1408452 (-2.80%)
helped: 58
HURT: 47
helped stats (abs) min: 9 max: 22604 x̄: 957.00 x̃: 74
helped stats (rel) min: 0.40% max: 18.81% x̄: 6.22% x̃: 3.03%
HURT stats (abs)   min: 5 max: 3720 x̄: 318.98 x̃: 49
HURT stats (rel)   min: 0.20% max: 34.50% x̄: 5.05% x̃: 2.12%
95% mean confidence interval for cycles value: -999.84 228.14
95% mean confidence interval for cycles %-change: -2.86% 0.51%
Inconclusive result (value mean confidence interval includes 0).

Ivy Bridge
total instructions in shared programs: 15266086 -> 15265983 (<.01%)
instructions in affected programs: 7272 -> 7169 (-1.42%)
helped: 3
HURT: 0
helped stats (abs) min: 21 max: 41 x̄: 34.33 x̃: 41
helped stats (rel) min: 0.66% max: 5.43% x̄: 2.44% x̃: 1.23%

total cycles in shared programs: 422930883 -> 422930336 (<.01%)
cycles in affected programs: 49259 -> 48712 (-1.11%)
helped: 3
HURT: 0
helped stats (abs) min: 106 max: 221 x̄: 182.33 x̃: 220
helped stats (rel) min: 0.71% max: 5.95% x̄: 2.46% x̃: 0.72%

No changes on any earilier Intel platforms.

Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4515>

---

 src/compiler/nir/nir_opt_algebraic.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 2122559e7d6..98ed3299691 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -1036,6 +1036,13 @@ optimizations.extend([
     ('pack_half_2x16', ('vec2', a, b))),
    (('ior', ('pack_half_2x16', ('vec2', a, 0)), ('pack_half_2x16', ('vec2', 0, b))),
     ('pack_half_2x16', ('vec2', a, b))),
+
+   (('ishl', ('pack_half_2x16_split', a, 0), 16), ('pack_half_2x16_split', 0, a)),
+   (('ushr', ('pack_half_2x16_split', 0, a), 16), ('pack_half_2x16_split', a, 0)),
+   (('extract_u16', ('pack_half_2x16_split', 0, a), 1), ('pack_half_2x16_split', a, 0)),
+
+   (('iadd', ('pack_half_2x16_split', a, 0), ('pack_half_2x16_split', 0, b)), ('pack_half_2x16_split', a, b)),
+   (('ior',  ('pack_half_2x16_split', a, 0), ('pack_half_2x16_split', 0, b)), ('pack_half_2x16_split', a, b)),
 ])
 
 # After the ('extract_u8', a, 0) pattern, above, triggers, there will be