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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Clang emits badly performing SSE instead of conditional moves for simple function with -O2"
href="https://llvm.org/bugs/show_bug.cgi?id=24888">24888</a>
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<th>Summary</th>
<td>Clang emits badly performing SSE instead of conditional moves for simple function with -O2
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.7
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>OrlandoMarinera@mailinator.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=14910" name="attach_14910" title="Repro example">attachment 14910</a> <a href="attachment.cgi?id=14910&action=edit" title="Repro example">[details]</a></span>
Repro example
Code attached. Tested on core2 cpu, 64bit, with clang 3.7.0.
Compiling with -O1 produces very compact assembly relying on `cmov`.
Switching to -O2 emits a mass of SSE instructions which ends up
being about 2x slower.
compile with -std=c++11</pre>
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