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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - wrong code (that hangs) by LTO at -O0 on x86_64-linux-gnu in 32-bit mode (affecting 3.4 and trunk)"
href="http://llvm.org/bugs/show_bug.cgi?id=19202">19202</a>
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<tr>
<th>Summary</th>
<td>wrong code (that hangs) by LTO at -O0 on x86_64-linux-gnu in 32-bit mode (affecting 3.4 and trunk)
</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>-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 current clang trunk and clang 3.4 miscompile the following code when using
LTO at -O0 on x86_64-linux-gnu in 32-bit mode (but not 64-bit). The generated
code hangs.
This is a regression from clang 3.3.
$ clang-trunk -v
clang version 3.5.0 (trunk 204228)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8.1
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/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
$
$ clang-trunk -m32 -O0 small.c; a.out
$ clang-trunk -flto -m32 -O1 small.c; a.out
$ clang-trunk -flto -m64 -O0 small.c; a.out
$ clang-3.3 -flto -m32 -O0 small.c; a.out
$
$ clang-trunk -flto -m32 -O0 small.c
$ a.out
^C
$
----------------------------------
int a, b;
int
main ()
{
int c = 1;
if (!(~4294967295UL))
for (; a < 1; a++)
b = c >= 2 || 1 >> c ? 0 : c;
return 0;
}</pre>
</div>
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