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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - bit operations optimised incorrectly"
href="http://llvm.org/bugs/show_bug.cgi?id=17283">17283</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>bit operations optimised incorrectly
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mjjunk47@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=11234" name="attach_11234" title="clang_packedbits_bug.C">attachment 11234</a> <a href="attachment.cgi?id=11234&action=edit" title="clang_packedbits_bug.C">[details]</a></span>
clang_packedbits_bug.C
Dear clang team,
Attached a simple test code which uses hamming weights to calculate the bit
count. I gives the correct result when compiled without optimisation but
incorrect when compiled with -O.
UNIX> clang++ clang_packedbits_bug.C
UNIX> ./a.out
c:316
UNIX> clang++ -O clang_packedbits_bug.C
UNIX> ./a.out
c:0
If I add e.g. any printing to the loop it is ok as well.</pre>
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