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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Loop unrolling doesn't take into account whether it will decrease or increase performance"
href="https://bugs.freedesktop.org/show_bug.cgi?id=83658#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Loop unrolling doesn't take into account whether it will decrease or increase performance"
href="https://bugs.freedesktop.org/show_bug.cgi?id=83658">bug 83658</a>
from <span class="vcard"><a class="email" href="mailto:eero.t.tamminen@intel.com" title="Eero Tamminen <eero.t.tamminen@intel.com>"> <span class="fn">Eero Tamminen</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=83658#c1">comment #1</a>)
<span class="quote">> FWIW there exists code to detect expressions that are constant within a loop
> (during loop analysis), I think this could be used as starting point for
> such optimization.</span >
Loop invariant code handling could also be the root cause making e.g. SynMark2
PSPhong 3x slower than it should be:
- code doesn't get unrolled with all the loop invariant code inside the loop
- this resulting in cascade effect that causes also other problems. e.g. stuff
which on Windows GL is handled with push & no sampler, changes to (unecessarily
looped) pull and makes thing sampler bound with Mesa instead of it being PS ALU
bound</pre>
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