Module: Mesa Branch: master Commit: f50400cc8040cf2d07de97e76d9b1ed144c5c8b4 URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=f50400cc8040cf2d07de97e76d9b1ed144c5c8b4

Author: Ian Romanick <ian.d.roman...@intel.com> Date: Wed Jan 31 11:11:02 2018 -0800 nir: Replace an odd comparison involving fmin of -b2f I noticed the fge version while looking at a shader for an unrelated reason. The feq version prevents a regression in a later change that performs strength reduction of some compares. Broadwell and Skylake had similar results. (Skylake shown) total instructions in shared programs: 14514808 -> 14514796 (<.01%) instructions in affected programs: 750 -> 738 (-1.60%) helped: 4 HURT: 0 helped stats (abs) min: 1 max: 5 x̄: 3.00 x̃: 3 helped stats (rel) min: 0.83% max: 1.96% x̄: 1.40% x̃: 1.40% 95% mean confidence interval for instructions value: -6.67 0.67 95% mean confidence interval for instructions %-change: -2.43% -0.36% Inconclusive result (value mean confidence interval includes 0). total cycles in shared programs: 533144939 -> 533144853 (<.01%) cycles in affected programs: 8911 -> 8825 (-0.97%) helped: 4 HURT: 0 helped stats (abs) min: 16 max: 32 x̄: 21.50 x̃: 19 helped stats (rel) min: 0.60% max: 1.89% x̄: 1.28% x̃: 1.31% 95% mean confidence interval for cycles value: -32.94 -10.06 95% mean confidence interval for cycles %-change: -2.30% -0.26% Cycles are helped. Haswell total instructions in shared programs: 13093785 -> 13093775 (<.01%) instructions in affected programs: 924 -> 914 (-1.08%) helped: 4 HURT: 2 helped stats (abs) min: 1 max: 5 x̄: 3.00 x̃: 3 helped stats (rel) min: 0.82% max: 1.95% x̄: 1.39% x̃: 1.39% HURT stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1 HURT stats (rel) min: 1.19% max: 1.19% x̄: 1.19% x̃: 1.19% 95% mean confidence interval for instructions value: -4.53 1.20 95% mean confidence interval for instructions %-change: -2.02% 0.97% Inconclusive result (value mean confidence interval includes 0). total cycles in shared programs: 409580553 -> 409580118 (<.01%) cycles in affected programs: 10909 -> 10474 (-3.99%) helped: 5 HURT: 1 helped stats (abs) min: 6 max: 222 x̄: 89.60 x̃: 18 helped stats (rel) min: 0.16% max: 24.72% x̄: 9.54% x̃: 1.78% HURT stats (abs) min: 13 max: 13 x̄: 13.00 x̃: 13 HURT stats (rel) min: 0.39% max: 0.39% x̄: 0.39% x̃: 0.39% 95% mean confidence interval for cycles value: -180.68 35.68 95% mean confidence interval for cycles %-change: -19.55% 3.79% Inconclusive result (value mean confidence interval includes 0). Ivy Bridge total instructions in shared programs: 11811851 -> 11811840 (<.01%) instructions in affected programs: 1032 -> 1021 (-1.07%) helped: 5 HURT: 1 helped stats (abs) min: 1 max: 5 x̄: 2.40 x̃: 1 helped stats (rel) min: 0.63% max: 1.95% x̄: 1.13% x̃: 0.97% HURT stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1 HURT stats (rel) min: 1.19% max: 1.19% x̄: 1.19% x̃: 1.19% 95% mean confidence interval for instructions value: -4.17 0.51 95% mean confidence interval for instructions %-change: -1.86% 0.36% Inconclusive result (value mean confidence interval includes 0). total cycles in shared programs: 257618403 -> 257618168 (<.01%) cycles in affected programs: 10784 -> 10549 (-2.18%) helped: 4 HURT: 2 helped stats (abs) min: 4 max: 220 x̄: 64.50 x̃: 17 helped stats (rel) min: 0.50% max: 24.34% x̄: 7.07% x̃: 1.72% HURT stats (abs) min: 9 max: 14 x̄: 11.50 x̃: 11 HURT stats (rel) min: 0.24% max: 0.42% x̄: 0.33% x̃: 0.33% 95% mean confidence interval for cycles value: -133.11 54.78 95% mean confidence interval for cycles %-change: -14.79% 5.59% Inconclusive result (value mean confidence interval includes 0). GM45, Iron Lake, and Sandy Bridge had similar results. (Sandy Bridge shown) total instructions in shared programs: 10533871 -> 10533859 (<.01%) instructions in affected programs: 865 -> 853 (-1.39%) helped: 4 HURT: 0 helped stats (abs) min: 1 max: 5 x̄: 3.00 x̃: 3 helped stats (rel) min: 0.63% max: 1.83% x̄: 1.22% x̃: 1.21% 95% mean confidence interval for instructions value: -6.67 0.67 95% mean confidence interval for instructions %-change: -2.16% -0.29% Inconclusive result (value mean confidence interval includes 0). total cycles in shared programs: 146139904 -> 146139852 (<.01%) cycles in affected programs: 15213 -> 15161 (-0.34%) helped: 4 HURT: 0 helped stats (abs) min: 3 max: 18 x̄: 13.00 x̃: 15 helped stats (rel) min: 0.15% max: 0.84% x̄: 0.39% x̃: 0.29% 95% mean confidence interval for cycles value: -23.79 -2.21 95% mean confidence interval for cycles %-change: -0.88% 0.09% Inconclusive result (%-change mean confidence interval includes 0). Signed-off-by: Ian Romanick <ian.d.roman...@intel.com> Reviewed-by: Samuel Iglesias Gonsálvez <sigles...@igalia.com> --- src/compiler/nir/nir_opt_algebraic.py | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index 43b2948431..553f82065a 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -152,6 +152,19 @@ optimizations = [ (('fge', ('fneg', ('b2f', a)), 0.0), ('inot', a)), + # fmin(-b2f(a), b) >= 0.0 + # -b2f(a) >= 0.0 && b >= 0.0 + # -b2f(a) == 0.0 && b >= 0.0 -b2f can only be 0 or -1, never >0 + # b2f(a) == 0.0 && b >= 0.0 + # a == False && b >= 0.0 + # !a && b >= 0.0 + # + # The fge in the second replacement is not a typo. I leave the proof that + # "fmin(-b2f(a), b) >= 0 <=> fmin(-b2f(a), b) == 0" as an exercise for the + # reader. + (('fge', ('fmin', ('fneg', ('b2f', a)), b), 0.0), ('iand', ('inot', a), ('fge', b, 0.0))), + (('feq', ('fmin', ('fneg', ('b2f', a)), b), 0.0), ('iand', ('inot', a), ('fge', b, 0.0))), + # 0.0 < fabs(a) # fabs(a) > 0.0 # fabs(a) != 0.0 because fabs(a) must be >= 0 _______________________________________________ mesa-commit mailing list mesa-commit@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-commit