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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - glLinkProgram() should fail when a varying is never written to in a previous stage"
href="https://bugs.freedesktop.org/show_bug.cgi?id=93339">93339</a>
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<th>Summary</th>
<td>glLinkProgram() should fail when a varying is never written to in a previous stage
</td>
</tr>
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<th>Product</th>
<td>Mesa
</td>
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<th>Version</th>
<td>git
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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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>glsl-compiler
</td>
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<th>Assignee</th>
<td>idr@freedesktop.org
</td>
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<th>Reporter</th>
<td>bugs@linkmauve.fr
</td>
</tr>
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<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=120455" name="attach_120455" title="Testcase exhibiting this bug, red patterns randomly happen when line 55 is commented.">attachment 120455</a> <a href="attachment.cgi?id=120455&action=edit" title="Testcase exhibiting this bug, red patterns randomly happen when line 55 is commented.">[details]</a></span>
Testcase exhibiting this bug, red patterns randomly happen when line 55 is
commented.
If a varying is declared in one stage and read from in the next stage, without
having been written to, the link step don’t fail and will generate a working
program object, but that varying will read from seemingly uninitialized video
memory (at least on i965, llvmpipe seems to read from 0-initialized memory
instead).
I haven’t looked at the specification, but I can’t see any usecase for this
specific behaviour, which should imo be reported to the user before they can
use the program object.</pre>
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</p>
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