[Mesa-dev] [PATCH 07/10] nir: Add algebraic optimizations for pointless shifts.

[Jason Ekstrand]

On Thu, Jan 22, 2015 at 9:09 AM, Matt Turner <mattst88 at gmail.com> wrote:

> On Thu, Jan 22, 2015 at 3:41 AM, Kenneth Graunke <kenneth at whitecape.org>
> wrote:
> > The GLSL IR optimization pass contained these; we may as well include
> > them too.
> >
> > No change in the number of NIR instructions on a shader-db run.
> >
> > total i965 instructions in shared programs: 6035397 -> 6035393 (-0.00%)
> > i965 instructions in affected programs:     772 -> 768 (-0.52%)
> > helped:                                     3 (all in glamor)
> >
> > Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> > ---
> >  src/glsl/nir/nir_opt_algebraic.py | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/src/glsl/nir/nir_opt_algebraic.py
> b/src/glsl/nir/nir_opt_algebraic.py
> > index cf16b19..58e71e0 100644
> > --- a/src/glsl/nir/nir_opt_algebraic.py
> > +++ b/src/glsl/nir/nir_opt_algebraic.py
> > @@ -83,6 +83,13 @@ optimizations = [
> >     # DeMorgan's Laws
> >     (('iand', ('inot', a), ('inot', b)), ('inot', ('ior',  a, b))),
> >     (('ior',  ('inot', a), ('inot', b)), ('inot', ('iand', a, b))),
> > +   # Shift optimizations
> > +   (('ishl', 0, a), 0),
>
> Shift zero by an unknown -> zero. Yes.
>
> > +   (('ishl', a, 0), 0),
>
> Shift an unknown by zero -> zero?!
>

Yeah, that needs to be fixed


>
> With those fixed and shader-db results confirmed,
>

Same

Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>


>
> Reviewed-by: Matt Turner <mattst88 at gmail.com>
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