<html>
<head>
<base href="https://llvm.org/bugs/" />
</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 --- - [LV] Loop vectorizer does not respect vectorize_width pragma at -Os/-Oz"
href="https://llvm.org/bugs/show_bug.cgi?id=27643">27643</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[LV] Loop vectorizer does not respect vectorize_width pragma at -Os/-Oz
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<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>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mssimpso@codeaurora.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mcrosier@codeaurora.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>When optimizing for size, the loop vectorizer chooses to not vectorize the
simple loop below due to the required run-time checks.
void f(int *a, int *b, int n) {
for (int i = 0; i < n; ++i)
a[i] = b[i];
}
Comments in the source suggest that vectorization can be forced with pragmas.
"#pragma clang loop vectorize(enable)" does indeed force vectorization, but
"#pragma clang loop vectorize_width(4)" does not. Specifying the width is
supposed to implicitly enable vectorization.</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>