<html>
<head>
<base href="http://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 --- - clang compiled c-ray 1.1 benchmarks up to 43% slower than gcc compiled versions"
href="http://llvm.org/bugs/show_bug.cgi?id=22657">22657</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang compiled c-ray 1.1 benchmarks up to 43% slower than gcc compiled versions
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>3.6
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Macintosh
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>howarth.mailing.lists@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The c-ray 1.1 benchmark, from
<a href="http://www.phoronix-test-suite.com/benchmark-files/c-ray-1.1.tar.gz">http://www.phoronix-test-suite.com/benchmark-files/c-ray-1.1.tar.gz</a>, exhibits
up to 43% slower performance when compiled under clang compared to when
compiled with gcc. Using "-O3 -march=native" on a Nehalem processor, the
following is observed...
clang 3.5.1
% ./RUN.full
c-ray-mt v1.1
Rendering took: 0 seconds (50 milliseconds)
c-ray-mt v1.1
Rendering took: 0 seconds (865 milliseconds)
c-ray-mt v1.1
Rendering took: 11 seconds (11254 milliseconds)
c-ray-mt v1.1
Rendering took: 2 seconds (2660 milliseconds)
clang 3.6-rc4
% ./RUN.full
c-ray-mt v1.1
Rendering took: 0 seconds (52 milliseconds)
c-ray-mt v1.1
Rendering took: 1 seconds (1054 milliseconds)
c-ray-mt v1.1
Rendering took: 13 seconds (13556 milliseconds)
c-ray-mt v1.1
Rendering took: 2 seconds (2850 milliseconds)
clang 3.7svn (r230135)
% ./RUN.full
c-ray-mt v1.1
Rendering took: 0 seconds (51 milliseconds)
c-ray-mt v1.1
Rendering took: 1 seconds (1051 milliseconds)
c-ray-mt v1.1
Rendering took: 13 seconds (13783 milliseconds)
c-ray-mt v1.1
Rendering took: 2 seconds (2863 milliseconds)
gcc 4.9.2
% ./RUN.full
c-ray-mt v1.1
Rendering took: 0 seconds (43 milliseconds)
c-ray-mt v1.1
Rendering took: 0 seconds (689 milliseconds)
c-ray-mt v1.1
Rendering took: 8 seconds (8786 milliseconds)
c-ray-mt v1.1
Rendering took: 2 seconds (2478 milliseconds)
gcc 5.0svn (r220888)
% ./RUN.full
c-ray-mt v1.1
Rendering took: 0 seconds (45 milliseconds)
c-ray-mt v1.1
Rendering took: 0 seconds (667 milliseconds)
c-ray-mt v1.1
Rendering took: 8 seconds (8727 milliseconds)
c-ray-mt v1.1
Rendering took: 2 seconds (2390 milliseconds)</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>