[Mesa-dev] [PATCH 3/3] i965/nir: use vectorization for non-scalar stages
Jason Ekstrand
jason at jlekstrand.net
Thu Oct 18 20:57:55 UTC 2018
On Thu, Oct 18, 2018 at 3:46 PM Ian Romanick <idr at freedesktop.org> wrote:
> On 10/18/2018 01:22 PM, Jason Ekstrand wrote:
> > On Thu, Oct 18, 2018 at 3:11 PM Ian Romanick <idr at freedesktop.org
> > <mailto:idr at freedesktop.org>> wrote:
> >
> > On 10/17/2018 11:33 AM, Jason Ekstrand wrote:
> > > From: Connor Abbott <cwabbott0 at gmail.com <mailto:
> cwabbott0 at gmail.com>>
> > >
> > > Shader-db results on Haswell:
> > >
> > > total instructions in shared programs: 2180337 -> 2154080
> (-1.20%)
> > > instructions in affected programs: 959766 -> 933509 (-2.74%)
> > > helped: 5653
> > > HURT: 2560
> > >
> > > total cycles in shared programs: 12339326 -> 12307102 (-0.26%)
> > > cycles in affected programs: 6102794 -> 6070570 (-0.53%)
> > > helped: 3838
> > > HURT: 4868
> >
> > Here's the results I got with these 3 patches on 322a919a41f:
> >
> > total instructions in shared programs: 13674046 -> 13643001 (-0.23%)
> > instructions in affected programs: 1248672 -> 1217627 (-2.49%)
> > helped: 7168
> > HURT: 2841
> > helped stats (abs) min: 1 max: 39 x̄: 5.40 x̃: 3
> > helped stats (rel) min: 0.21% max: 33.33% x̄: 4.55% x̃: 3.54%
> > HURT stats (abs) min: 1 max: 21 x̄: 2.71 x̃: 3
> > HURT stats (rel) min: 0.19% max: 22.73% x̄: 3.86% x̃: 3.53%
> > 95% mean confidence interval for instructions value: -3.23 -2.97
> > 95% mean confidence interval for instructions %-change: -2.28% -2.05%
> > Instructions are helped.
> >
> > total cycles in shared programs: 373694400 -> 373745788 (0.01%)
> > cycles in affected programs: 23171532 -> 23222920 (0.22%)
> > helped: 4890
> > HURT: 5632
> > helped stats (abs) min: 2 max: 1268 x̄: 52.04 x̃: 34
> > helped stats (rel) min: 0.04% max: 45.71% x̄: 7.43% x̃: 4.64%
> > HURT stats (abs) min: 2 max: 6042 x̄: 54.30 x̃: 32
> > HURT stats (rel) min: 0.05% max: 60.66% x̄: 8.19% x̃: 6.21%
> > 95% mean confidence interval for cycles value: 1.30 8.47
> > 95% mean confidence interval for cycles %-change: 0.73% 1.14%
> > Cycles are HURT.
> >
> > total spills in shared programs: 82569 -> 82572 (<.01%)
> > spills in affected programs: 70 -> 73 (4.29%)
> > helped: 0
> > HURT: 3
> >
> > total fills in shared programs: 93445 -> 93449 (<.01%)
> > fills in affected programs: 71 -> 75 (5.63%)
> > helped: 0
> > HURT: 4
> >
> > This is pretty different from your result... and not good. :( What
> SHA
> > of master were you on?
> >
> >
> > For one thing, I scrubbed all the non-vec4 programs from the results
> > because this doesn't affect FS. I'm not sure what master; something
> > from the last two days; I just rebased. Maybe you have a newer
> shader-db?
>
> I doubt my shader-db is newer. The last time I updated was when you
> added a bunch of shaders. :) Scrubbing FS programs should only affect
> the values shown in "total XXX in shader programs", right? Or did you
> do something other than
>
./report.py <(grep -v SIMD before.txt) <(grep -v SIMD after.txt)
>
> When I do that, I get 'total ...' numbers a bit closer to, but still
> larger than, yours.
>
> Looking at the actual data, the shaders most hurt for cycles are all
> shaders that have been in shader-db for years... lots of Unigine and
> L4D2. :( The spills / fills hurt are all TES in Tomb Raider.
>
One other thing is that my Haswell numbers were taking by using ./run -p
hsw on a KBL. It's possible you have more/less features enabled or
something.
--Jason
> > > Most of the hurt programs seem to be because we generate extra
> > MOV's due
> > > to vectorizing things. For example, in
> > > shaders/non-free/steam/anomaly-2/158.shader_test, this:
> > >
> > > add(8) g116<1>.xyF g12<4,4,1>.xyyyF g1.4<0,4,1>.xyyyF
> > { align16 NoDDClr 1Q };
> > > add(8) g117<1>.xyF g12<4,4,1>.xyyyF g1.4<0,4,1>.zwwwF
> > { align16 NoDDClr 1Q };
> > > add(8) g116<1>.zwF g12<4,4,1>.xxxyF
> > -g1.4<0,4,1>.xxxyF { align16 NoDDChk 1Q };
> > > add(8) g117<1>.zwF g12<4,4,1>.xxxyF
> > -g1.4<0,4,1>.zzzwF { align16 NoDDChk 1Q };
> > >
> > > Turns into this:
> > >
> > > add(8) g13<1>F g12<4,4,1>.xyxyF g1.4<0,4,1>F {
> > align16 1Q };
> > > add(8) g14<1>F g12<4,4,1>.xyxyF -g1.4<0,4,1>F {
> > align16 1Q };
> > > mov(8) g116<1>.xyD g13<4,4,1>.xyyyD {
> > align16 NoDDClr 1Q };
> > > mov(8) g117<1>.xyD g13<4,4,1>.zwwwD {
> > align16 NoDDClr 1Q };
> > > mov(8) g116<1>.zwD g14<4,4,1>.xxxyD {
> > align16 NoDDChk 1Q };
> > > mov(8) g117<1>.zwD g14<4,4,1>.zzzwD {
> > align16 NoDDChk 1Q };
> > >
> > > So we eliminated two add's, but then had to introduce four mov's to
> > > transpose the result. Some of the hurt is because vectorization
> > is a bit
> > > over-aggressive and we vectorize something when we should have
> left it
> > > as a scalar and CSEd it. Unfortunately, this is all really tricky
> > to do
> > > as it involves the interactions between many different components.
> > > ---
> > > src/intel/compiler/brw_nir.c | 6 ++++++
> > > 1 file changed, 6 insertions(+)
> > >
> > > diff --git a/src/intel/compiler/brw_nir.c
> > b/src/intel/compiler/brw_nir.c
> > > index 297845b89b7..564fd004a94 100644
> > > --- a/src/intel/compiler/brw_nir.c
> > > +++ b/src/intel/compiler/brw_nir.c
> > > @@ -568,6 +568,12 @@ brw_nir_optimize(nir_shader *nir, const
> > struct brw_compiler *compiler,
> > > OPT(nir_copy_prop);
> > > OPT(nir_opt_dce);
> > > OPT(nir_opt_cse);
> > > +
> > > + if (!is_scalar) {
> > > + OPT(nir_opt_vectorize);
> > > + OPT(nir_copy_prop);
> > > + }
> > > +
> > > OPT(nir_opt_peephole_select, 0);
> > > OPT(nir_opt_intrinsics);
> > > OPT(nir_opt_algebraic);
> > >
> >
>
>
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