<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 --- - pragma unroll ignores non-power-of-2 counts"
href="https://llvm.org/bugs/show_bug.cgi?id=26957">26957</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>pragma unroll ignores non-power-of-2 counts
</td>
</tr>
<tr>
<th>Product</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</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>compiler-rt
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>evstupac@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>consider we have the following loop:
for (i = 0; i < n; i++) {
if (k == 3) s += a[i] * a[i];
else s += a[i];
k++
if(k == 7) k = 0;
}
I see that unroll on 7 is profitable here. However even if I insert:
#pragma unroll(7)
I didn't get the loop unrolled.
The potential gain for this loop is ~3 times.
(assuming we add epilogue unrolling: <a href="http://reviews.llvm.org/D18158">http://reviews.llvm.org/D18158</a>)</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>