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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - Implement a NIR -> vec4 pass"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89580#c30">Comment # 30</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - Implement a NIR -> vec4 pass"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89580">bug 89580</a>
from <span class="vcard"><a class="email" href="mailto:kenneth@whitecape.org" title="Kenneth Graunke <kenneth@whitecape.org>"> <span class="fn">Kenneth Graunke</span></a>
</span></b>
<pre>Hi Eduardo, AntÃa,
FYI, I've mostly gotten SIMD8 Geometry Shaders (new on Broadwell) working -
which is the first backend using NIR for geometry shaders.
You can find my work-in-progress branch here:
<a href="http://cgit.freedesktop.org/~kwg/mesa/log/?h=simd8gs">http://cgit.freedesktop.org/~kwg/mesa/log/?h=simd8gs</a>
I've done things a little differently than the old vec4 backend - namely, I
moved the vertex count (how many times EmitVertex() has been called) into NIR,
introducing new intrinsics.
My thinking is that NIR's optimizations should be able to constant
fold/propagate the counter values, so in common/simple cases, NIR will simply
eliminate the "safety check" if statements, as they'll be if (true). Knowing
that the vertex count is an immediate may allow us to avoid per-slot-offset
messages as well, and should also help us use the "Static Vertex Count" feature
on Broadwell.
It's not quite done yet: I haven't actually added code to do safety checks yet;
there are a few Piglit regressions still, and a few tests try to use 700
registers for the payload data :) But I figured I'd share it so you can see
where I'm going with this, and in case you wanted to reuse the NIR intrinsics.</pre>
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