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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [llvm-exegesis] Ignore unsupported instructions via UnsupportedFeatures"
href="https://bugs.llvm.org/show_bug.cgi?id=37602">37602</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[llvm-exegesis] Ignore unsupported instructions via UnsupportedFeatures
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>andrea.dibiagio@gmail.com, clement.courbet@gmail.com, craig.topper@gmail.com, gchatelet@google.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
</td>
</tr>
<tr>
<th>Depends on</th>
<td>37601
</td>
</tr>
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<th>Blocks</th>
<td>32325
</td>
</tr></table>
<p>
<div>
<pre>Using the script detailed in
<a href="http://llvm.org/docs/CommandGuide/llvm-exegesis.html">http://llvm.org/docs/CommandGuide/llvm-exegesis.html</a> is very slow as we end up
testing instructions that we know aren't supported on the CPU, but we still
have to wait for the JIT to fail to move on.
It would be better if:
(a) llvm-exegesis made use of the scheduler model's UnsupportedFeatures field
to test if the instruction is supported and if not, early out. In particular
this would help considerably with older CPUs that don't support all the AVX512
instructions......
(b) the models made use of the UnsupportedFeatures field to ignore ISAs that it
doesn't support see [<a class="bz_bug_link
bz_status_NEW "
title="NEW - [X86] Scheduler models should use UnsupportedFeatures to indicate unsupported ISAs"
href="show_bug.cgi?id=37601">Bug #37601</a>] - for SandyBridge/Haswell where we need to
"support" additional ISAs we could at least hack the field locally to match the
test CPU.</pre>
</div>
</p>
<div id="referenced">
<hr style="border: 1px dashed #969696">
<b>Referenced Bugs:</b>
<ul>
<li>
[<a class="bz_bug_link
bz_status_NEW "
title="NEW - [META][X86] Improve implementation and use of X86 scheduler models"
href="https://bugs.llvm.org/show_bug.cgi?id=32325">Bug 32325</a>] [META][X86] Improve implementation and use of X86 scheduler models
</li>
<li>
[<a class="bz_bug_link
bz_status_NEW "
title="NEW - [X86] Scheduler models should use UnsupportedFeatures to indicate unsupported ISAs"
href="https://bugs.llvm.org/show_bug.cgi?id=37601">Bug 37601</a>] [X86] Scheduler models should use UnsupportedFeatures to indicate unsupported ISAs
</li>
</ul>
</div>
<br>
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