[Mesa-dev] [PATCH V3 1/2] i965/blorp: Add bilinear filtering of samples for multisample scaled blits
stereotype441 at gmail.com
Wed Jun 26 16:28:39 PDT 2013
On 26 June 2013 14:57, Anuj Phogat <anuj.phogat at gmail.com> wrote:
> On Tue, Jun 25, 2013 at 10:27 AM, Paul Berry <stereotype441 at gmail.com>
> > This seems like a lot of work to accomplish what is effectively a lookup
> > table. If this winds up becoming a performance bottleneck, you might
> > to consider passing the table in via a push constant, and using indirect
> > addressing to convert sample index to sample number.
> Yes, that would be helpful. Is it acceptable to do this optimization as a
> follow up patch?
Yes, that seems completely reasonable.
> > I'm confused why we need loops from 0 to 7 here. It looks like you're
> > trying to interpolate each component of the SIMD8 register separately.
> > shouldn't be necessary.
> Output of each SIMD16 sampler instruction (send) is written to 8 grf
> So, I'm looping from 0 to 7 to interpolate all these 8 registers. If we
> the loop counter, we end up with color data 'not-interpolated' in few color
> channels. Does this explain your concern?
Aha! The 8 comes from 4 color channels * 2 registers each (since we're
doing SIMD16, and a register holds only 8 values). I get it now. A
comment to explain this would probably be useful.
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