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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang produces incorrect code with loop/expression at -O2"
href="http://llvm.org/bugs/show_bug.cgi?id=16130">16130</a>
</td>
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<tr>
<th>Summary</th>
<td>clang produces incorrect code with loop/expression at -O2
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<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>
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<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>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The following testcase produces incorrect results when compiled with current
clang trunk at -O2 or above on x86_64-linux-gnu. clang 3.2 does not have this
behavior.
$ clang-trunk -v
clang version 3.4 (trunk 182568)
Target: x86_64-pc-linux-gnu
Thread model: posix
$ clang-trunk -Os wrong.c
$ ./a.out
8
$ clang-3.2 -O2 wrong.c
$ ./a.out
8
$ clang-trunk -O3 wrong.c
$ ./a.out
0
$
----------------------------
int printf (const char *, ...);
int a;
int
fn1 ()
{
int b = 0;
for (; b != 13; b =b+8)
if ((a = b)) return 1;
return 0;
}
int
main ()
{
int c = fn1 ();
printf ("%d\n", a);
return 0;
}</pre>
</div>
</p>
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