<html>
<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body><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> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [IVB,BYT] GPU hang on deqp-gles31.functional.separate.shader.random"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97083">bug 97083</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr></table>
<p>
<div>
<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [IVB,BYT] GPU hang on deqp-gles31.functional.separate.shader.random"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97083#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [IVB,BYT] GPU hang on deqp-gles31.functional.separate.shader.random"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97083">bug 97083</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>Curro figured this one out. The problem was the NoDDClear/NoDDCheck flags on
the PLN instructions. Normally, we do a (-f0.0) PLN with NoDDClear (for helper
pixels) and a (+f0.0) PLN with NoDDCheck. This works fine at the top level,
because at least one pixel won't be a helper invocation, so the (-f0.0) PLN
with NoDDClear will actually execute.
But with my (broken) rework, we started emitting PLNs inside control flow. If
only helper pixels take a certain control flow path, the (-f0.0) PLN with
NoDDClear might not ever execute, leaving the register dependency set, so the
next instruction that tries to touch that register would hang.
So, move to top is a real solution to this problem, not just papering over it.
I've also sent a patch to the mailing list that eliminates the PLN dependency
hints, which will allow us to move PLNs into control flow safely (if we want
to):
<a href="https://lists.freedesktop.org/archives/mesa-dev/2016-August/124946.html">https://lists.freedesktop.org/archives/mesa-dev/2016-August/124946.html</a></pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the QA Contact for the bug.</li>
</ul>
</body>
</html>