[Mesa-dev] [PATCH 11/22 v2] nir: Recognize some more open-coded fmin / fmax

[Jason Ekstrand]

On Mon, Mar 5, 2018 at 2:25 PM, Ian Romanick <idr at freedesktop.org> wrote:

> On 03/05/2018 02:07 PM, Jason Ekstrand wrote:
> > On Mon, Mar 5, 2018 at 11:11 AM, Ian Romanick <idr at freedesktop.org
> > <mailto:idr at freedesktop.org>> wrote:
> >
> >     On 02/28/2018 12:48 PM, Jason Ekstrand wrote:
> >     > Rb
> >
> >     For both or just this one?
> >
> >
> > If you put the ~ on there, both.
>
> I'm not sure what you mean.  That's all the other patch ([PATCH 11.1/22]
> nir: Mark bcsel-to-fmin (or fmax) transformations as inexact) does.
>

Sorry, I got confused.  Yes, RB to both.


> >     > On Wed, Feb 28, 2018 at 12:18 PM, Ian Romanick <
> idr at freedesktop.org <mailto:idr at freedesktop.org>
> >     > <mailto:idr at freedesktop.org <mailto:idr at freedesktop.org>>> wrote:
> >     >
> >     >     From: Ian Romanick <ian.d.romanick at intel.com <mailto:
> ian.d.romanick at intel.com>
> >     >     <mailto:ian.d.romanick at intel.com
> >     <mailto:ian.d.romanick at intel.com>>>
> >     >
> >     >     This transformation is inexact because section 4.7.1 (Range and
> >     >     Precision) says:
> >     >
> >     >         Operations and built-in functions that operate on a NaN
> >     are not
> >     >         required to return a NaN as the result.
> >     >
> >     >     The fmin or fmax might not return NaN in cases where the
> original
> >     >     expression would be required to return NaN.
> >     >
> >     >     v2: Reorder operands and mark as inexact.  The latter
> suggested by
> >     >     Jason.
> >     >
> >     >     shader-db results:
> >     >
> >     >     Haswell, Broadwell, and Skylake had similar results. (Skylake
> >     shown)
> >     >     total instructions in shared programs: 14514817 -> 14514808
> >     (<.01%)
> >     >     instructions in affected programs: 229 -> 220 (-3.93%)
> >     >     helped: 3
> >     >     HURT: 0
> >     >     helped stats (abs) min: 1 max: 4 x̄: 3.00 x̃: 4
> >     >     helped stats (rel) min: 2.86% max: 4.12% x̄: 3.70% x̃: 4.12%
> >     >
> >     >     total cycles in shared programs: 533145211 -> 533144939 (<.01%)
> >     >     cycles in affected programs: 37268 -> 36996 (-0.73%)
> >     >     helped: 8
> >     >     HURT: 0
> >     >     helped stats (abs) min: 2 max: 134 x̄: 34.00 x̃: 2
> >     >     helped stats (rel) min: 0.02% max: 14.22% x̄: 3.53% x̃: 0.05%
> >     >
> >     >     Sandy Bridge and Ivy Bridge had similar results. (Ivy Bridge
> >     shown)
> >     >     total cycles in shared programs: 257618409 -> 257618403 (<.01%)
> >     >     cycles in affected programs: 12582 -> 12576 (-0.05%)
> >     >     helped: 3
> >     >     HURT: 0
> >     >     helped stats (abs) min: 2 max: 2 x̄: 2.00 x̃: 2
> >     >     helped stats (rel) min: 0.05% max: 0.05% x̄: 0.05% x̃: 0.05%
> >     >
> >     >     No changes on Iron Lake or GM45.
> >     >
> >     >     Signed-off-by: Ian Romanick <ian.d.romanick at intel.com
> >     <mailto:ian.d.romanick at intel.com>
> >     >     <mailto:ian.d.romanick at intel.com
> >     <mailto:ian.d.romanick at intel.com>>>
> >     >     ---
> >     >      src/compiler/nir/nir_opt_algebraic.py | 2 ++
> >     >      1 file changed, 2 insertions(+)
> >     >
> >     >     diff --git a/src/compiler/nir/nir_opt_algebraic.py
> >     >     b/src/compiler/nir/nir_opt_algebraic.py
> >     >     index d40d59b..17f4d9c 100644
> >     >     --- a/src/compiler/nir/nir_opt_algebraic.py
> >     >     +++ b/src/compiler/nir/nir_opt_algebraic.py
> >     >     @@ -170,6 +170,8 @@ optimizations = [
> >     >         (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
> >     >         (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
> >     >         (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
> >     >     +   (('~bcsel', ('fge', a, b), b, a), ('fmin', a, b)),
> >     >     +   (('~bcsel', ('fge', b, a), b, a), ('fmax', a, b)),
> >     >         (('bcsel', ('inot', a), b, c), ('bcsel', a, c, b)),
> >     >         (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
> >     >         (('bcsel', a, True, 'b at bool'), ('ior', a, b)),
> >     >     --
> >     >     2.9.5
> >     >
> >     >     _______________________________________________
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> >     >
> >     >
> >
> >
>
>
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