From d1ed4ffe0b70762477709e699f95c73602f9dc5a Mon Sep 17 00:00:00 2001 From: Ian Romanick Date: Tue, 6 Feb 2018 17:27:53 -0800 Subject: [PATCH] nir: Use De Morgan's Law on logic compounded comparisons MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The replacement of the comparison operators must happen during this step. If it does not, the next pass of nir_opt_algebraic will reapply De Morgan's Law in the "opposite direction" before performing dead code elimination. The resulting infinite loop will eventually get OOM killed. Haswell, Broadwell, and Skylake had similar results. (Broadwell shown) total instructions in shared programs: 14808185 -> 14808036 (<.01%) instructions in affected programs: 13758 -> 13609 (-1.08%) helped: 39 HURT: 0 helped stats (abs) min: 1 max: 10 x̄: 3.82 x̃: 3 helped stats (rel) min: 0.44% max: 1.55% x̄: 0.98% x̃: 1.01% 95% mean confidence interval for instructions value: -4.67 -2.97 95% mean confidence interval for instructions %-change: -1.09% -0.88% Instructions are helped. total cycles in shared programs: 559438333 -> 559435832 (<.01%) cycles in affected programs: 199160 -> 196659 (-1.26%) helped: 42 HURT: 3 helped stats (abs) min: 2 max: 184 x̄: 61.50 x̃: 51 helped stats (rel) min: 0.02% max: 6.94% x̄: 1.41% x̃: 1.40% HURT stats (abs) min: 2 max: 40 x̄: 27.33 x̃: 40 HURT stats (rel) min: 0.05% max: 0.74% x̄: 0.51% x̃: 0.74% 95% mean confidence interval for cycles value: -71.47 -39.69 95% mean confidence interval for cycles %-change: -1.64% -0.93% Cycles are helped. Sandy Bridge and Ivy Bridge had similar results. (Ivy Bridge shown) total instructions in shared programs: 11811776 -> 11811553 (<.01%) instructions in affected programs: 15201 -> 14978 (-1.47%) helped: 39 HURT: 0 helped stats (abs) min: 1 max: 20 x̄: 5.72 x̃: 6 helped stats (rel) min: 0.44% max: 2.53% x̄: 1.30% x̃: 1.26% 95% mean confidence interval for instructions value: -7.21 -4.23 95% mean confidence interval for instructions %-change: -1.48% -1.12% Instructions are helped. total cycles in shared programs: 257617270 -> 257614589 (<.01%) cycles in affected programs: 212107 -> 209426 (-1.26%) helped: 45 HURT: 0 helped stats (abs) min: 2 max: 180 x̄: 59.58 x̃: 54 helped stats (rel) min: 0.02% max: 6.02% x̄: 1.30% x̃: 1.32% 95% mean confidence interval for cycles value: -74.02 -45.14 95% mean confidence interval for cycles %-change: -1.59% -1.01% Cycles are helped. Iron Lake total instructions in shared programs: 7886648 -> 7886515 (<.01%) instructions in affected programs: 14106 -> 13973 (-0.94%) helped: 29 HURT: 0 helped stats (abs) min: 1 max: 10 x̄: 4.59 x̃: 4 helped stats (rel) min: 0.35% max: 1.83% x̄: 0.90% x̃: 0.81% 95% mean confidence interval for instructions value: -5.65 -3.52 95% mean confidence interval for instructions %-change: -1.03% -0.76% Instructions are helped. total cycles in shared programs: 178100812 -> 178100396 (<.01%) cycles in affected programs: 67970 -> 67554 (-0.61%) helped: 29 HURT: 0 helped stats (abs) min: 2 max: 40 x̄: 14.34 x̃: 12 helped stats (rel) min: 0.15% max: 1.69% x̄: 0.58% x̃: 0.54% 95% mean confidence interval for cycles value: -18.30 -10.39 95% mean confidence interval for cycles %-change: -0.71% -0.45% Cycles are helped. GM45 total instructions in shared programs: 4857939 -> 4857872 (<.01%) instructions in affected programs: 7426 -> 7359 (-0.90%) helped: 15 HURT: 0 helped stats (abs) min: 1 max: 10 x̄: 4.47 x̃: 4 helped stats (rel) min: 0.33% max: 1.80% x̄: 0.87% x̃: 0.77% 95% mean confidence interval for instructions value: -6.06 -2.87 95% mean confidence interval for instructions %-change: -1.06% -0.67% Instructions are helped. total cycles in shared programs: 122167930 -> 122167654 (<.01%) cycles in affected programs: 43118 -> 42842 (-0.64%) helped: 15 HURT: 0 helped stats (abs) min: 4 max: 40 x̄: 18.40 x̃: 16 helped stats (rel) min: 0.15% max: 1.69% x̄: 0.62% x̃: 0.54% 95% mean confidence interval for cycles value: -25.03 -11.77 95% mean confidence interval for cycles %-change: -0.82% -0.41% Cycles are helped. Signed-off-by: Ian Romanick Reviewed-by: Samuel Iglesias Gonsálvez --- src/compiler/nir/nir_opt_algebraic.py | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index b1e266259fa..f6800b419ba 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -24,6 +24,7 @@ # Jason Ekstrand (jason@jlekstrand.net) import nir_algebraic +import itertools # Convenience variables a = 'a' @@ -545,6 +546,14 @@ optimizations = [ 'options->lower_unpack_snorm_4x8'), ] +invert = {'feq': 'fne', 'fne': 'feq', 'fge': 'flt', 'flt': 'fge' } + +for left, right in list(itertools.combinations(invert.keys(), 2)) + zip(invert.keys(), invert.keys()): + optimizations.append((('inot', ('ior(is_used_once)', (left, a, b), (right, c, d))), + ('iand', (invert[left], a, b), (invert[right], c, d)))) + optimizations.append((('inot', ('iand(is_used_once)', (left, a, b), (right, c, d))), + ('ior', (invert[left], a, b), (invert[right], c, d)))) + def fexp2i(exp, bits): # We assume that exp is already in the right range. if bits == 32: