On 08/02/2018 03:26 PM, Jason Ekstrand wrote: > This one bothers me a bit. People don't usually expect integer > calculations so be modified at all so to replace an expression that > takes in an internet and sometimes returns a different one with a no-op > seems rather unexpected. Then again, GLSL doesn't actually specify > precision or range of anything so we'd be right to use a double instead > of a float in which case it would be a no-op.
That is fair. It makes me a bit nervous too, and that's why I marked them as imprecise. :) I looked into some of the shaders that are affected by this transformation. What I saw looked more like weirdness added by a HSLS-to-GLSL translation layer than anything done intentionally by the programmer. For example, several compute shaders have code like: s.xy = vec4(textureSize(...)).xy; t = ivec4(s.xyxy); t = t + ivec4(-1); c = texelFetch(..., t); Note to self: A really clever optimization would translate this to texelFecthOffset. There were also a bunch of vertex shaders affected (mostly in a single application). They also had some odd patterns that looked like something weird done by a translation layer. > This isn't a nak, just a statement of nervousness. It's probably ok... > > --Jason > > On August 2, 2018 11:19:36 "Ian Romanick" <i...@freedesktop.org> wrote: > >> From: Ian Romanick <ian.d.roman...@intel.com> >> >> Broadwell and Skylake had similar results. (Skylake shown) >> total instructions in shared programs: 14277978 -> 14277620 (<.01%) >> instructions in affected programs: 36957 -> 36599 (-0.97%) >> helped: 76 >> HURT: 1 >> helped stats (abs) min: 2 max: 90 x̄: 4.89 x̃: 4 >> helped stats (rel) min: 0.44% max: 5.88% x̄: 1.04% x̃: 0.87% >> HURT stats (abs) min: 14 max: 14 x̄: 14.00 x̃: 14 >> HURT stats (rel) min: 0.36% max: 0.36% x̄: 0.36% x̃: 0.36% >> 95% mean confidence interval for instructions value: -7.06 -2.24 >> 95% mean confidence interval for instructions %-change: -1.28% -0.77% >> Instructions are helped. >> >> total cycles in shared programs: 532584581 -> 532580716 (<.01%) >> cycles in affected programs: 973591 -> 969726 (-0.40%) >> helped: 76 >> HURT: 1 >> helped stats (abs) min: 2 max: 9940 x̄: 159.80 x̃: 32 >> helped stats (rel) min: <.01% max: 8.70% x̄: 1.15% x̃: 1.19% >> HURT stats (abs) min: 8280 max: 8280 x̄: 8280.00 x̃: 8280 >> HURT stats (rel) min: 2.10% max: 2.10% x̄: 2.10% x̃: 2.10% >> 95% mean confidence interval for cycles value: -386.98 286.59 >> 95% mean confidence interval for cycles %-change: -1.41% -0.81% >> Inconclusive result (value mean confidence interval includes 0). >> >> total spills in shared programs: 8127 -> 8116 (-0.14%) >> spills in affected programs: 108 -> 97 (-10.19%) >> helped: 1 >> HURT: 0 >> >> total fills in shared programs: 11090 -> 11086 (-0.04%) >> fills in affected programs: 440 -> 436 (-0.91%) >> helped: 1 >> HURT: 1 >> >> Haswell >> total instructions in shared programs: 12979174 -> 12979054 (<.01%) >> instructions in affected programs: 9040 -> 8920 (-1.33%) >> helped: 14 >> HURT: 1 >> helped stats (abs) min: 2 max: 34 x̄: 8.79 x̃: 6 >> helped stats (rel) min: 0.41% max: 7.04% x̄: 2.66% x̃: 1.14% >> HURT stats (abs) min: 3 max: 3 x̄: 3.00 x̃: 3 >> HURT stats (rel) min: 0.19% max: 0.19% x̄: 0.19% x̃: 0.19% >> 95% mean confidence interval for instructions value: -13.58 -2.42 >> 95% mean confidence interval for instructions %-change: -3.94% -1.01% >> Instructions are helped. >> >> total cycles in shared programs: 411227148 -> 411212880 (<.01%) >> cycles in affected programs: 630506 -> 616238 (-2.26%) >> helped: 15 >> HURT: 0 >> helped stats (abs) min: 2 max: 11192 x̄: 951.20 x̃: 38 >> helped stats (rel) min: <.01% max: 16.01% x̄: 3.92% x̃: 0.17% >> 95% mean confidence interval for cycles value: -2544.28 641.88 >> 95% mean confidence interval for cycles %-change: -6.89% -0.94% >> Inconclusive result (value mean confidence interval includes 0). >> >> total spills in shared programs: 78626 -> 78623 (<.01%) >> spills in affected programs: 42 -> 39 (-7.14%) >> helped: 1 >> HURT: 0 >> >> total fills in shared programs: 80111 -> 80104 (<.01%) >> fills in affected programs: 140 -> 133 (-5.00%) >> helped: 1 >> HURT: 1 >> >> Ivy Bridge >> total instructions in shared programs: 11684101 -> 11684030 (<.01%) >> instructions in affected programs: 3080 -> 3009 (-2.31%) >> helped: 4 >> HURT: 1 >> helped stats (abs) min: 5 max: 59 x̄: 18.50 x̃: 5 >> helped stats (rel) min: 6.47% max: 7.04% x̄: 6.87% x̃: 6.99% >> HURT stats (abs) min: 3 max: 3 x̄: 3.00 x̃: 3 >> HURT stats (rel) min: 0.15% max: 0.15% x̄: 0.15% x̃: 0.15% >> 95% mean confidence interval for instructions value: -45.59 17.19 >> 95% mean confidence interval for instructions %-change: -9.38% -1.56% >> Inconclusive result (value mean confidence interval includes 0). >> >> total cycles in shared programs: 258407697 -> 258389653 (<.01%) >> cycles in affected programs: 328323 -> 310279 (-5.50%) >> helped: 5 >> HURT: 0 >> helped stats (abs) min: 32 max: 14908 x̄: 3608.80 x̃: 32 >> helped stats (rel) min: 1.26% max: 17.22% x̄: 9.30% x̃: 10.60% >> 95% mean confidence interval for cycles value: -11616.71 4399.11 >> 95% mean confidence interval for cycles %-change: -16.56% -2.03% >> Inconclusive result (value mean confidence interval includes 0). >> >> total spills in shared programs: 4537 -> 4528 (-0.20%) >> spills in affected programs: 64 -> 55 (-14.06%) >> helped: 1 >> HURT: 0 >> >> total fills in shared programs: 4823 -> 4815 (-0.17%) >> fills in affected programs: 189 -> 181 (-4.23%) >> helped: 1 >> HURT: 1 >> >> Sandy Bridge >> total instructions in shared programs: 10488464 -> 10488449 (<.01%) >> instructions in affected programs: 272 -> 257 (-5.51%) >> helped: 3 >> HURT: 0 >> helped stats (abs) min: 5 max: 5 x̄: 5.00 x̃: 5 >> helped stats (rel) min: 5.49% max: 5.56% x̄: 5.51% x̃: 5.49% >> >> total cycles in shared programs: 150263359 -> 150263263 (<.01%) >> cycles in affected programs: 7978 -> 7882 (-1.20%) >> helped: 3 >> HURT: 0 >> helped stats (abs) min: 32 max: 32 x̄: 32.00 x̃: 32 >> helped stats (rel) min: 1.15% max: 1.23% x̄: 1.20% x̃: 1.23% >> >> No changes on Iron Lake or GM45. >> >> Signed-off-by: Ian Romanick <ian.d.roman...@intel.com> >> --- >> src/compiler/nir/nir_opt_algebraic.py | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/src/compiler/nir/nir_opt_algebraic.py >> b/src/compiler/nir/nir_opt_algebraic.py >> index c4f46b56d95..9aeafcb8c46 100644 >> --- a/src/compiler/nir/nir_opt_algebraic.py >> +++ b/src/compiler/nir/nir_opt_algebraic.py >> @@ -455,6 +455,14 @@ optimizations = [ >> (('iabs', ('b2i', a)), ('b2i', a)), >> (('inot', ('f2b', a)), ('feq', a, 0.0)), >> >> + # Ironically, mark these as imprecise because removing the >> conversions may >> + # preserve more precision than doing the conversions (e.g., >> + # uint(float(0x81818181u)) == 0x81818200). >> + (('~f2i32', ('i2f32', 'a@32')), a), >> + (('~f2i32', ('u2f32', 'a@32')), a), >> + (('~f2u32', ('i2f32', 'a@32')), a), >> + (('~f2u32', ('u2f32', 'a@32')), a), >> + >> # Packing and then unpacking does nothing >> (('unpack_64_2x32_split_x', ('pack_64_2x32_split', a, b)), a), >> (('unpack_64_2x32_split_y', ('pack_64_2x32_split', a, b)), b), >> -- >> 2.14.4 >> >> _______________________________________________ >> mesa-dev mailing list >> mesa-dev@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/mesa-dev > > > 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