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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - gather cycle counts inaccurate on Intel Hardware"
href="https://bugs.llvm.org/show_bug.cgi?id=41686">41686</a>
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<th>Summary</th>
<td>gather cycle counts inaccurate on Intel Hardware
</td>
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<th>Product</th>
<td>tools
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>llvm-mca
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>jon.kennedy@intel.com
</td>
</tr>
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<th>CC</th>
<td>andrea.dibiagio@gmail.com, llvm-bugs@lists.llvm.org, matthew.davis@sony.com
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<div>
<pre><a href="https://godbolt.org/z/yA_GLT">https://godbolt.org/z/yA_GLT</a>
The above code snippet approximates the sequence of instructions (from the
inner loop) to take approx 3303 cycles for 100 iterations. This includes a
gather.
When run on a real skylake based CPU (i7-8700K), it takes approximately ~1230
cycles.
Please update the latency/throughput numbers for the gather instruction within
llvm-mca to better reflect the real performance of the intel architectures.</pre>
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