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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Miscompilation of abs_vec3_vert_xvary_ref.vert in WebGL conformance"
href="https://bugs.freedesktop.org/show_bug.cgi?id=94073">94073</a>
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<th>Summary</th>
<td>Miscompilation of abs_vec3_vert_xvary_ref.vert in WebGL conformance
</td>
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<th>Product</th>
<td>Mesa
</td>
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<th>Version</th>
<td>11.0
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>Drivers/DRI/i965
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<th>Assignee</th>
<td>idr@freedesktop.org
</td>
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<th>Reporter</th>
<td>bztdlinux@gmail.com
</td>
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<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
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<pre>The test abs_vec3_vert_xvary.test.html fails due to the reference vertex shader
being miscompiled. The test can be reproduced by visiting this page with
Firefox (preferably Nightly).
<a href="https://www.khronos.org/registry/webgl/conformance-suites/1.0.2/conformance/ogles/GL/abs/abs_001_to_006.html">https://www.khronos.org/registry/webgl/conformance-suites/1.0.2/conformance/ogles/GL/abs/abs_001_to_006.html</a>
The test passes on Chromium, but the vertex shader submitted is the same,
checked with apitrace. It's unclear what is causing the behavior difference.
The error happens between the SSA and final NIR stages. Note that ssa_16 is
dropped and never used, leading to the blue channel never having the absolute
value applied:
<a href="https://pastebin.mozilla.org/8859127">https://pastebin.mozilla.org/8859127</a>
Trivial modifications to the shader make it compile correctly. For example,
replacing
if((c[2] < 0.0)) c[2] *= -1.0;
with
float x = c.b;
if (x < 0.0) x *= -1.0;
c.b = x;
This is one of a series of similar failures on the Khronos test. The entire
test can be accessed here:
<a href="https://www.khronos.org/registry/webgl/conformance-suites/1.0.2/webgl-conformance-tests.html">https://www.khronos.org/registry/webgl/conformance-suites/1.0.2/webgl-conformance-tests.html</a></pre>
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</p>
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