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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang hangs on valid code at -O1 and above on x86_64-linux-gnu"
href="http://llvm.org/bugs/show_bug.cgi?id=20079">20079</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang hangs on valid code at -O1 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 testcase causes the current clang trunk to hang when compiling at
-O1 and above in both 32-bit and 64-bit modes on x86_64-linux-gnu.
This is a regression from 3.4.
$ clang-trunk -v
clang version 3.5.0 (trunk 211159)
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
$
$ time clang-trunk -O0 -c small.c
0.00user 0.00system 0:00.07elapsed 17%CPU (0avgtext+0avgdata 41840maxresident)k
0inputs+8outputs (0major+3835minor)pagefaults 0swaps
$ time clang-3.4 -O1 -c small.c
0.01user 0.00system 0:00.06elapsed 23%CPU (0avgtext+0avgdata 47680maxresident)k
0inputs+8outputs (0major+4053minor)pagefaults 0swaps
$ time clang-3.4 -O3 -c small.c
0.00user 0.01system 0:00.09elapsed 17%CPU (0avgtext+0avgdata 48192maxresident)k
0inputs+8outputs (0major+4085minor)pagefaults 0swaps
$
$ timeout -s 9 60 clang-trunk -O1 -c small.c
Killed
$
--------------------------------
int a, b[1], c, *d, e, f, g, *h;
void
fn1 ()
{
d = h = &b[0];
f = -a;
g = -1;
e = (g ^ f) * (d == &c);
}</pre>
</div>
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