[Mesa-dev] [PATCH 00/10] [RFC] Probably useless algebraic optimizations

[Brian Paul]

Some of these optimizations are pretty obscure and I can't imagine a 
real shader hitting them.

What's the cost of checking for these cases?  I don't know how expensive 
the equals() methods are.

Do we want to litter the optimizer with cases that may never be used in 
practice?

-Brian


On 07/15/2014 04:27 PM, Thomas Helland wrote:
> So, a little update on these patches.
> I've written some shaders for hitting each
> specific case in the patch-series.
>
> This shows that:
> Patch 1 (X - X) == 0,    and
> Patch 9 (A - neg(B)) == A + B
> have no effect at all.
>
> The rest of the patches do indeed have
> a positive effect on the special-case shader.
>
> If anyone wants to have a look at the shaders
> then let me know. I could always put them
> in a dropbox-folder, or github, or something.
>
> The report from shader-db (sorted by patch-number):
>
> Patch 2:
> helped: shaders/mine/a_or_nota.shader_test fs16:          16 -> 5 (-68.75%)
> helped: shaders/mine/a_or_nota.shader_test fs8:           16 -> 5 (-68.75%)
> helped: shaders/mine/a_or_nota.shader_test vs:            11 -> 5 (-54.55%)
>
> Patch 3:
> helped: shaders/mine/a_and_nota.shader_test fs16:         16 -> 5 (-68.75%)
> helped: shaders/mine/a_and_nota.shader_test fs8:          16 -> 5 (-68.75%)
> helped: shaders/mine/a_and_nota.shader_test vs:           11 -> 5 (-54.55%)
>
> Patch 4:
> helped: shaders/mine/or_and.shader_test fs16:             16 -> 14 (-12.50%)
> helped: shaders/mine/or_and.shader_test fs8:              16 -> 14 (-12.50%)
> helped: shaders/mine/or_and.shader_test vs:               11 -> 10 (-9.09%)
>
> Patch 5:
> helped: shaders/mine/minOver.shader_test fs16:            8 -> 5 (-37.50%)
> helped: shaders/mine/minOver.shader_test fs8:             8 -> 5 (-37.50%)
> helped: shaders/mine/minOver.shader_test vs:              6 -> 5 (-16.67%)
> helped: shaders/mine/minUnder.shader_test fs16:           8 -> 5 (-37.50%)
> helped: shaders/mine/minUnder.shader_test fs8:            8 -> 5 (-37.50%)
> helped: shaders/mine/minUnder.shader_test vs:             6 -> 5 (-16.67%)
>
> Patch 6
> helped: shaders/mine/maxOver.shader_test fs16:            8 -> 5 (-37.50%)
> helped: shaders/mine/maxOver.shader_test fs8:             8 -> 5 (-37.50%)
> helped: shaders/mine/maxOver.shader_test vs:              6 -> 5 (-16.67%)
> helped: shaders/mine/maxUnder.shader_test fs16:           8 -> 5 (-37.50%)
> helped: shaders/mine/maxUnder.shader_test fs8:            8 -> 5 (-37.50%)
> helped: shaders/mine/maxUnder.shader_test vs:             6 -> 5 (-16.67%)
>
> Patch 7:
> helped: shaders/mine/loglog.shader_test fs16:             17 -> 11 (-35.29%)
> helped: shaders/mine/loglog.shader_test fs8:              17 -> 11 (-35.29%)
> helped: shaders/mine/loglog.shader_test vs:               7 -> 6 (-14.29%)
>
> Patch 8:
> helped: shaders/mine/expexp.shader_test fs16:             17 -> 11 (-35.29%)
> helped: shaders/mine/expexp.shader_test fs8:              17 -> 11 (-35.29%)
> helped: shaders/mine/expexp.shader_test vs:               7 -> 6 (-14.29%)
>
> Patch 10:
> helped: shaders/mine/pow0x.shader_test fs16:              8 -> 5 (-37.50%)
> helped: shaders/mine/pow0x.shader_test fs8:               8 -> 5 (-37.50%)
> helped: shaders/mine/pow0x.shader_test vs:                6 -> 5 (-16.67%)
> helped: shaders/mine/powx-1.shader_test fs16:             11 -> 5 (-54.55%)
> helped: shaders/mine/powx-1.shader_test fs8:              11 -> 5 (-54.55%)
> helped: shaders/mine/powx-1.shader_test vs:               7 -> 5 (-28.57%)
> helped: shaders/mine/powx0.shader_test fs16:              8 -> 5 (-37.50%)
> helped: shaders/mine/powx0.shader_test fs8:               8 -> 5 (-37.50%)
> helped: shaders/mine/powx0.shader_test vs:                6 -> 5 (-16.67%)
>
>
>
> 2014-07-15 0:22 GMT+02:00 <thomashelland90 at gmail.com
> <mailto:thomashelland90 at gmail.com>>:
>
>     From: Thomas Helland <thomashelland90 at gmail.com
>     <mailto:thomashelland90 at gmail.com>>
>
>     When writing that A || (A && B) patch some
>     days ago I also wrote some other patches
>     that have no impact on my collection of shaders.
>     (shader-db + Some TF2 and Portal-shaders).
>     No reduction in instruction count, and no
>     significant increase in compilation time.
>
>     I decided to put them up here anyway, as
>     with your collection of shaders maybe YMMV.
>
>     These are mostly RFC-quality, and not all are
>     as complete and nicely formatted as they could be.
>     Possibly some are also implemented incorrectly.
>     (I'm still trying to get a good understanding of
>     the buildup of the ir, the visitors, etc)
>
>     Feel free to do with these patches as you please;
>     Ignore, test, review, flame, make cookies...
>
>     Thomas Helland (10):
>        glsl: Optimize X - X -> 0
>        glsl: Optimize !A || A == 1
>        glsl: Optimize !A && A == 0
>        glsl: Optimize (A || B) && A == A
>        glsl: Optimize min(-8, sin(x)) == -8 and similar
>        glsl: Optimize max(8, sin(x)) == 8 and similar
>        glsl: Optimize log(x) + log(y) == log(x*y)
>        glsl: Optimize exp(x)*exp(y) == exp(x+y)
>        glsl: Optimize A - neg(B) == A + B  and  neg(A) - B == neg(A + B)
>        glsl: Optimize some more pow() special cases
>
>       src/glsl/opt_algebraic.cpp | 152
>     +++++++++++++++++++++++++++++++++++++++++++++
>       1 file changed, 152 insertions(+)
>
>     --
>     2.0.0
>
>
>
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> https://urldefense.proofpoint.com/v1/url?u=http://lists.freedesktop.org/mailman/listinfo/mesa-dev&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=lGQMzzTgII0I7jefp2FHq7WtZ%2BTLs8wadB%2BiIj9xpBY%3D%0A&m=AYR8hWikWHJNvkG02hozH%2BwkDnyXmqwN9EKzxX2zk2E%3D%0A&s=7fc598ca37f58cc3cc06507056ce8a3d0c0b87e7e32bc6b65ec2a192c2261265
>