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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - wrong code at -Os and above on x86_64-linux-gnu"
href="http://llvm.org/bugs/show_bug.cgi?id=18000">18000</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -Os and above on x86_64-linux-gnu
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</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>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 and clang 3.3 at
-Os and above on x86_64-linux-gnu in both 32-bit and 64-bit modes.
It also affects clang 3.2 at -Os (but neither -O2 nor -O3).
This is a regression from clang 3.1.
$ clang-trunk -v
clang version 3.4 (trunk 195148)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
$
$
$ clang-trunk -O1 small.c; a.out
0
$ clang-3.1 -Os small.c; a.out
0
$
$ clang-trunk -Os small.c; a.out
512
$ clang-3.3 -Os small.c; a.out
512
$ clang-3.2 -Os small.c; a.out
512
$
------------------------------------
int printf (const char *, ...);
int a, b, c, d;
char e;
void
foo ()
{
a = 0;
}
int
main ()
{
unsigned char f;
for (; b < 1; b++)
for (e = 1; e >= 0; e--)
{
d = 0;
if (a)
break;
f = 179 * e;
c = f << 1;
foo ();
}
printf ("%d\n", c);
return 0;
}</pre>
</div>
</p>
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