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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - wrong code at optimization levels -Os and above (both 32-bit and 64-bit modes)"
href="http://llvm.org/bugs/show_bug.cgi?id=16522">16522</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at optimization levels -Os and above (both 32-bit and 64-bit modes)
</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>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>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>su@cs.ucdavis.edu
</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 is miscompiled by the current clang trunk on
x86_64-linux-gnu at -Os and above (in both 32-bit and 64-bit modes). This is a
regression as both clang 3.2 and 3.3 produce correct code.
$ clang-trunk -v
clang version 3.4 (trunk 185306)
Target: x86_64-pc-linux-gnu
Thread model: posix
$ clang-trunk -Os reduced.c
$ a.out
-2
$ clang-3.3 -Os reduced.c
$ a.out
-1
$ clang-3.2 -Os reduced.c
$ a.out
-1
$
-------------------------------------------
int printf (const char *, ...);
int a, b = 1, *c = &a;
void
foo (int p)
{
int t;
for (t = 0; t < 16; t++)
p ^= -1;
*c = ~(p & b);
}
int
main ()
{
foo (0);
printf ("%d\n", a);
return 0;
}</pre>
</div>
</p>
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