[Mesa-dev] [PATCH 07/13] nir: Transform expressions of b2f(a) and b2f(b) to a || b

[Thomas Helland]

With the correction of the fmin/fmax pattern in this one and patch 10,
and the inot version of the pattern in patch 9 and 11,
patch 7, and 9-11 are:

Reviewed-by: Thomas Helland <thomashelland90 at gmail.com>

I think that should be the whole series.

2018-08-03 1:38 GMT+02:00 Ian Romanick <idr at freedesktop.org>:
> On 08/02/2018 02:10 PM, Thomas Helland wrote:
>> 2018-08-02 20:19 GMT+02:00 Ian Romanick <idr at freedesktop.org>:
>>> From: Ian Romanick <ian.d.romanick at intel.com>
>>>
>>> All Gen6+ platforms had pretty similar results. (Skylake shown)
>>> total instructions in shared programs: 14277184 -> 14276964 (<.01%)
>>> instructions in affected programs: 10082 -> 9862 (-2.18%)
>>> helped: 37
>>> HURT: 1
>>> helped stats (abs) min: 1 max: 30 x̄: 5.97 x̃: 4
>>> helped stats (rel) min: 0.14% max: 16.00% x̄: 5.23% x̃: 2.04%
>>> HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
>>> HURT stats (rel)   min: 0.70% max: 0.70% x̄: 0.70% x̃: 0.70%
>>> 95% mean confidence interval for instructions value: -7.87 -3.71
>>> 95% mean confidence interval for instructions %-change: -6.98% -3.16%
>>> Instructions are helped.
>>>
>>> total cycles in shared programs: 532577990 -> 532577062 (<.01%)
>>> cycles in affected programs: 170959 -> 170031 (-0.54%)
>>> helped: 33
>>> HURT: 9
>>> helped stats (abs) min: 2 max: 120 x̄: 30.91 x̃: 30
>>> helped stats (rel) min: 0.02% max: 7.65% x̄: 2.66% x̃: 1.13%
>>> HURT stats (abs)   min: 2 max: 24 x̄: 10.22 x̃: 8
>>> HURT stats (rel)   min: 0.09% max: 1.79% x̄: 0.61% x̃: 0.22%
>>> 95% mean confidence interval for cycles value: -31.23 -12.96
>>> 95% mean confidence interval for cycles %-change: -2.90% -1.02%
>>> Cycles are helped.
>>>
>>> Iron Lake and GM45 had similar results. (Iron Lake shown)
>>> total instructions in shared programs: 7781539 -> 7781301 (<.01%)
>>> instructions in affected programs: 10169 -> 9931 (-2.34%)
>>> helped: 32
>>> HURT: 0
>>> helped stats (abs) min: 2 max: 20 x̄: 7.44 x̃: 6
>>> helped stats (rel) min: 0.47% max: 17.02% x̄: 4.03% x̃: 1.88%
>>> 95% mean confidence interval for instructions value: -9.53 -5.34
>>> 95% mean confidence interval for instructions %-change: -5.94% -2.12%
>>> Instructions are helped.
>>>
>>> total cycles in shared programs: 177878590 -> 177878932 (<.01%)
>>> cycles in affected programs: 78706 -> 79048 (0.43%)
>>> helped: 7
>>> HURT: 21
>>> helped stats (abs) min: 6 max: 34 x̄: 24.57 x̃: 28
>>> helped stats (rel) min: 0.15% max: 8.33% x̄: 4.66% x̃: 6.37%
>>> HURT stats (abs)   min: 2 max: 86 x̄: 24.48 x̃: 22
>>> HURT stats (rel)   min: 0.01% max: 4.28% x̄: 1.21% x̃: 0.70%
>>> 95% mean confidence interval for cycles value: 0.30 24.13
>>> 95% mean confidence interval for cycles %-change: -1.52% 1.01%
>>> Inconclusive result (%-change mean confidence interval includes 0).
>>>
>>> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
>>> ---
>>>  src/compiler/nir/nir_opt_algebraic.py | 19 +++++++++++++++++++
>>>  1 file changed, 19 insertions(+)
>>>
>>> diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
>>> index 8300d6d01f5..4d60467fbac 100644
>>> --- a/src/compiler/nir/nir_opt_algebraic.py
>>> +++ b/src/compiler/nir/nir_opt_algebraic.py
>>> @@ -166,6 +166,25 @@ optimizations = [
>>>
>>>     (('fge', ('fneg', ('b2f', a)), 0.0), ('inot', a)),
>>>
>>> +   (('fne', ('fadd', ('b2f', a), ('b2f', b)), 0.0), ('ior', a, b)),
>>> +   (('fne', ('fmin', ('b2f', a), ('b2f', b)), 0.0), ('ior', a, b)),
>>
>> Maybe I'm just too sleepy, but shouldn't this be either
>>
>> (('fne', ('fmax', ('b2f', a), ('b2f', b)), 0.0), ('ior', a, b)),
>>
>> or
>>
>> (('fne', ('fmin', ('b2f', a), ('b2f', b)), 0.0), ('iand', a, b)),
>
> Yes... which means that patch 10 is also incorrect.
>
>>> +   (('fne', ('bcsel', a, 1.0, ('b2f', b))   , 0.0), ('ior', a, b)),
>>> +   (('fne', ('b2f', a), ('fneg', ('b2f', b))),      ('ior', a, b)),
>>> +
>>> +   # -(b2f(a) + b2f(b)) < 0
>>> +   # 0 < b2f(a) + b2f(b)
>>> +   # 0 != b2f(a) + b2f(b)       b2f must be 0 or 1, so the sum is non-negative
>>> +   # a || b
>>> +   (('flt', ('fneg', ('fadd', ('b2f', a), ('b2f', b))), 0.0), ('ior', a, b)),
>>> +   (('flt', 0.0, ('fadd', ('b2f', a), ('b2f', b))), ('ior', a, b)),
>>> +
>>> +   # Some optimizations (below) convert things like (a < b || c < b) into
>>> +   # (min(a, c) < b).  However, this interfers with the previous optimizations
>>> +   # that try to remove comparisons with negated sums of b2f.  This just
>>> +   # breaks that apart.
>>> +   (('flt', ('fmin', c, ('fneg', ('fadd', ('b2f', a), ('b2f', b)))), 0.0),
>>> +    ('ior', ('flt', c, 0.0), ('ior', a, b))),
>>> +
>>>     (('~flt', ('fadd', a, b), a), ('flt', b, 0.0)),
>>>     (('~fge', ('fadd', a, b), a), ('fge', b, 0.0)),
>>>     (('~feq', ('fadd', a, b), a), ('feq', b, 0.0)),
>>> --
>>> 2.14.4
>>>
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