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nir/algebraic: Mark some logic-joined comparison reductions as exact 

This also prevents some fossil-db regressions in "spir-v: Mark floating
point comparisons exact".

v2: Mark the fmin / fmax in the replacement exact to prevent other
optimizations from ruining the NaN-clensing property of the fmin / fmax.
Suggested by Rhys.  Don't assume that constants are not NaN because some
components of a vector might be NaN while others are numbers.  Noticed
by Rhys.  This causes ~8 more shaders in Age of Wonders III (dxvk) to
regress on cycles (not instructions) by less than 1% when "spir-v: Mark
floating point comparisons exact" is applied.  This difference is too
small to care.

All Intel platforms had similar results. (Tiger Lake shown)
total instructions in shared programs: 20908668 -> 20908670 (<.01%)
instructions in affected programs: 9196 -> 9198 (0.02%)
helped: 10
HURT: 5
helped stats (abs) min: 1 max: 2 x̄: 1.40 x̃: 1
helped stats (rel) min: 0.02% max: 5.41% x̄: 2.20% x̃: 2.16%
HURT stats (abs)   min: 2 max: 6 x̄: 3.20 x̃: 3
HURT stats (rel)   min: 2.44% max: 16.67% x̄: 9.39% x̃: 12.50%
95% mean confidence interval for instructions value: -1.22 1.49
95% mean confidence interval for instructions %-change: -2.08% 5.41%
Inconclusive result (value mean confidence interval includes 0).

total cycles in shared programs: 473515330 -> 473515288 (<.01%)
cycles in affected programs: 67146 -> 67104 (-0.06%)
helped: 10
HURT: 7
helped stats (abs) min: 1 max: 36 x̄: 15.90 x̃: 17
helped stats (rel) min: 0.01% max: 1.29% x̄: 0.66% x̃: 0.89%
HURT stats (abs)   min: 1 max: 48 x̄: 16.71 x̃: 4
HURT stats (rel)   min: 0.08% max: 1.94% x̄: 0.87% x̃: 0.19%
95% mean confidence interval for cycles value: -13.88 8.94
95% mean confidence interval for cycles %-change: -0.56% 0.49%
Inconclusive result (value mean confidence interval includes 0).

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6358>
This commit is contained in:
Ian Romanick 2020-07-08 12:53:07 -07:00 committed by Marge Bot
parent 71961c73a9
commit 9167324a86
1 changed files with 18 additions and 12 deletions
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30
src/compiler/nir/nir_opt_algebraic.py
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@ -598,14 +598,20 @@ optimizations.extend([
('fsat', ('fadd', ('fneg', a), b)), '!options->lower_fsat'),
(('extract_u8', ('imin', ('imax', a, 0), 0xff), 0), ('imin', ('imax', a, 0), 0xff)),
(('~ior', ('flt(is_used_once)', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
(('~ior', ('flt(is_used_once)', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
(('~ior', ('fge(is_used_once)', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
(('~ior', ('fge(is_used_once)', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
(('~ior', ('flt', a, '#b'), ('flt', a, '#c')), ('flt', a, ('fmax', b, c))),
(('~ior', ('flt', '#a', c), ('flt', '#b', c)), ('flt', ('fmin', a, b), c)),
(('~ior', ('fge', a, '#b'), ('fge', a, '#c')), ('fge', a, ('fmin', b, c))),
(('~ior', ('fge', '#a', c), ('fge', '#b', c)), ('fge', ('fmax', a, b), c)),
# The ior versions are exact because fmin and fmax will always pick a
# non-NaN value, if one exists. Therefore (a < NaN) || (a < c) == a <
# fmax(NaN, c) == a < c. Mark the fmin or fmax in the replacement as exact
# to prevent other optimizations from ruining the "NaN clensing" property
# of the fmin or fmax.
(('ior', ('flt(is_used_once)', a, b), ('flt', a, c)), ('flt', a, ('!fmax', b, c))),
(('ior', ('flt(is_used_once)', a, c), ('flt', b, c)), ('flt', ('!fmin', a, b), c)),
(('ior', ('fge(is_used_once)', a, b), ('fge', a, c)), ('fge', a, ('!fmin', b, c))),
(('ior', ('fge(is_used_once)', a, c), ('fge', b, c)), ('fge', ('!fmax', a, b), c)),
(('ior', ('flt', a, '#b'), ('flt', a, '#c')), ('flt', a, ('!fmax', b, c))),
(('ior', ('flt', '#a', c), ('flt', '#b', c)), ('flt', ('!fmin', a, b), c)),
(('ior', ('fge', a, '#b'), ('fge', a, '#c')), ('fge', a, ('!fmin', b, c))),
(('ior', ('fge', '#a', c), ('fge', '#b', c)), ('fge', ('!fmax', a, b), c)),
(('~iand', ('flt(is_used_once)', a, b), ('flt', a, c)), ('flt', a, ('fmin', b, c))),
(('~iand', ('flt(is_used_once)', a, c), ('flt', b, c)), ('flt', ('fmax', a, b), c)),
(('~iand', ('fge(is_used_once)', a, b), ('fge', a, c)), ('fge', a, ('fmax', b, c))),
@ -643,10 +649,10 @@ for s in [16, 32, 64]:
# used once as this ensures that the number of comparisons will not
# increase. The sources to the ior and iand are not symmetric, so the
# rules have to be duplicated to get this behavior.
(('~ior', ('flt(is_used_once)', 0.0, 'a@{}'.format(s)), ('flt', 'b@{}'.format(s), 0.0)), ('flt', 0.0, ('fmax', a, ('fneg', b)))),
(('~ior', ('flt', 0.0, 'a@{}'.format(s)), ('flt(is_used_once)', 'b@{}'.format(s), 0.0)), ('flt', 0.0, ('fmax', a, ('fneg', b)))),
(('~ior', ('fge(is_used_once)', 0.0, 'a@{}'.format(s)), ('fge', 'b@{}'.format(s), 0.0)), ('fge', 0.0, ('fmin', a, ('fneg', b)))),
(('~ior', ('fge', 0.0, 'a@{}'.format(s)), ('fge(is_used_once)', 'b@{}'.format(s), 0.0)), ('fge', 0.0, ('fmin', a, ('fneg', b)))),
(('ior', ('flt(is_used_once)', 0.0, 'a@{}'.format(s)), ('flt', 'b@{}'.format(s), 0.0)), ('flt', 0.0, ('fmax', a, ('fneg', b)))),
(('ior', ('flt', 0.0, 'a@{}'.format(s)), ('flt(is_used_once)', 'b@{}'.format(s), 0.0)), ('flt', 0.0, ('fmax', a, ('fneg', b)))),
(('ior', ('fge(is_used_once)', 0.0, 'a@{}'.format(s)), ('fge', 'b@{}'.format(s), 0.0)), ('fge', 0.0, ('fmin', a, ('fneg', b)))),
(('ior', ('fge', 0.0, 'a@{}'.format(s)), ('fge(is_used_once)', 'b@{}'.format(s), 0.0)), ('fge', 0.0, ('fmin', a, ('fneg', b)))),
(('~iand', ('flt(is_used_once)', 0.0, 'a@{}'.format(s)), ('flt', 'b@{}'.format(s), 0.0)), ('flt', 0.0, ('fmin', a, ('fneg', b)))),
(('~iand', ('flt', 0.0, 'a@{}'.format(s)), ('flt(is_used_once)', 'b@{}'.format(s), 0.0)), ('flt', 0.0, ('fmin', a, ('fneg', b)))),
(('~iand', ('fge(is_used_once)', 0.0, 'a@{}'.format(s)), ('fge', 'b@{}'.format(s), 0.0)), ('fge', 0.0, ('fmax', a, ('fneg', b)))),