[Mesa-dev] [PATCH 1/6] nir: Convert ineg(b2i(a)) to a if it's a boolean.

[Jason Ekstrand]

On Aug 10, 2016 1:00 AM, "Erik Faye-Lund" <kusmabite at gmail.com> wrote:
>
> On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke <kenneth at whitecape.org>
wrote:
> > On Haswell (GL 3.3):
> >
> > total instructions in shared programs: 6211678 -> 6211584 (-0.00%)
> > instructions in affected programs: 18968 -> 18874 (-0.50%)
> > helped: 62
> > HURT: 0
> > LOST:   0
> > GAINED: 4
> >
> > On Broadwell (GL 4.4):
> >
> > total instructions in shared programs: 11638930 -> 11638181 (-0.01%)
> > instructions in affected programs: 84768 -> 84019 (-0.88%)
> > helped: 505
> > HURT: 45
> >
> > Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> > ---
> >  src/compiler/nir/nir_opt_algebraic.py | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/src/compiler/nir/nir_opt_algebraic.py
b/src/compiler/nir/nir_opt_algebraic.py
> > index 0f0896b..1cf614c 100644
> > --- a/src/compiler/nir/nir_opt_algebraic.py
> > +++ b/src/compiler/nir/nir_opt_algebraic.py
> > @@ -180,6 +180,7 @@ optimizations = [
> >     (('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),
> >     (('fsat', ('fadd', ('b2f', a), ('b2f', b))), ('b2f', ('ior', a,
b))),
> >     (('iand', 'a at bool', 1.0), ('b2f', a)),
> > +   (('ineg', ('b2i', 'a at bool')), a),
> >     (('flt', ('fneg', ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
> >     (('flt', ('fsub', 0.0, ('b2f', a)), 0), a), # Generated by TGSI
KILL_IF.
> >     # Comparison with the same args.  Note that these are not done for
>
> Are you sure this shouldn't be conditional? This being an improvement
> sounds like an intel-ism, and not something that applies to most
> hardware...

Why? You're replacing two instructions with zero. That should help everyone.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20160810/6e459420/attachment.html>