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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 --- - wrong code at -Os (affecting all clang versions after 3.0 on x86_64-linux-gnu and MacOS X)"
href="http://llvm.org/bugs/show_bug.cgi?id=18447">18447</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -Os (affecting all clang versions after 3.0 on x86_64-linux-gnu and MacOS X)
</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 older
versions from clang 3.0) on x86_64-linux-gnu and MacOS X at -Os in both 32-bit
and 64-bit modes.
This is a regression from 2.9.
$ clang-trunk -v
clang version 3.5 (trunk 199011)
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
29052
$ clang-2.9 -Os small.c; a.out
29052
$
$ clang-trunk -Os small.c; a.out
-36484
$
---------------------------------
int printf (const char *, ...);
short a, c;
int b, d, r;
static unsigned int
foo ()
{
int e;
b = 0;
for (a = 0; a < 2; a++)
{
if (b != 1)
{
e = a - 7;
c = e * 60694;
r = c;
}
for (; d; d++)
;
}
return 0;
}
int
main ()
{
foo ();
printf ("%d\n", r);
return 0;
}</pre>
</div>
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