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<body><span class="vcard"><a class="email" href="mailto:mattst88@gmail.com" title="Matt Turner <mattst88@gmail.com>"> <span class="fn">Matt Turner</span></a>
</span> changed
<a class="bz_bug_link
bz_status_NEW "
title="NEW - i965/fs: Better heuristics on when to drop from SIMD16 to SIMD8, on register spilling"
href="https://bugs.freedesktop.org/show_bug.cgi?id=85505">bug 85505</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Assignee</td>
<td>idr@freedesktop.org
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<td>mattst88@gmail.com
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<td style="text-align:right;">Summary</td>
<td>Better heuristics on when to drop from SIMD16 to SIMD8, on register spilling
</td>
<td>i965/fs: Better heuristics on when to drop from SIMD16 to SIMD8, on register spilling
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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - i965/fs: Better heuristics on when to drop from SIMD16 to SIMD8, on register spilling"
href="https://bugs.freedesktop.org/show_bug.cgi?id=85505#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - i965/fs: Better heuristics on when to drop from SIMD16 to SIMD8, on register spilling"
href="https://bugs.freedesktop.org/show_bug.cgi?id=85505">bug 85505</a>
from <span class="vcard"><a class="email" href="mailto:mattst88@gmail.com" title="Matt Turner <mattst88@gmail.com>"> <span class="fn">Matt Turner</span></a>
</span></b>
<pre>I'd be surprised to see a shader that spilled the same number of registers in
SIMD8 and SIMD16. But yes, there are improvements we should make.
I've noticed that we often schedule the SIMD8 program to minimize delays
between dependent instructions at the code of higher register usage, but since
the SIMD16 program uses more registers we're not able to perform the same
schedule. So instead we schedule the SIMD16 program to minimize register usage,
which drastically increases latency. I suspect in cases like this the SIMD16
program is slower.
I've been planning to look at this, so I'll assign this bug to myself.</pre>
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