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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - nested loops produces wrong result at -O3"
href="http://llvm.org/bugs/show_bug.cgi?id=16166">16166</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>nested loops produces wrong result at -O3
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<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>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dhazeghi@yahoo.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 following code produces incorrect results when compiled with current clang
trunk at -O3 on x86_64-linux. This is a regression from clang 3.2.
$ clang-trunk -v
clang version 3.4 (trunk 182759)
Target: x86_64-pc-linux-gnu
Thread model: posix
$ clang-trunk -O2 wrong.c
$ ./a.out
-19
$ clang-3.2 -O3 wrong.c
$ ./a.out
-19
$ clang-trunk -O3 wrong.c
$ ./a.out
-564288184
$
---------------------
int printf (const char *, ...);
int a, b, c, d, e, f, g, h;
int
main ()
{
f = 22;
for (; f <= 53; f++)
{
b = 0;
for (; b > -19; b--)
if (e)
break;
}
printf ("%d\n", b);
return 0;
}</pre>
</div>
</p>
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