<html>
<head>
<base href="http://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Loop vectorizer miscompile"
href="http://bugs.llvm.org/show_bug.cgi?id=32135">32135</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Loop vectorizer miscompile
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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>
<tr>
<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>craig.topper@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=18052" name="attach_18052" title="Test case">attachment 18052</a> <a href="attachment.cgi?id=18052&action=edit" title="Test case">[details]</a></span>
Test case
The attached test case produces different output when compiled at -O1 and -O2.
The power of 2 trip count of the first loop seems to be significant. Values of
64, 128, and 256 all expose the problem. 16 does not.
It's also significant that the index for the second loop is a smaller type than
the first loop. If the same index type is used for both the loop is reduced to
a single store before the loop vectorizer even runs.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>