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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - LoopIdiom regression: ctlz no longer recognized"
href="https://bugs.llvm.org/show_bug.cgi?id=51722">51722</a>
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<th>Summary</th>
<td>LoopIdiom regression: ctlz no longer recognized
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>david.bolvansky@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
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<pre>unsigned long long FIO_highbit64(unsigned long long v)
{
unsigned count = 0;
v >>= 1;
while (v) { v >>= 1; count++; }
return count;
}
Since LLVM 13, we lost recognized "@llvm.ctlz.i64".
<a href="https://godbolt.org/z/nodKdfab4">https://godbolt.org/z/nodKdfab4</a></pre>
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