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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - wrong code by LTO at -Os (only) on x86_64-linux-gnu (affecting trunk and 3.4)"
href="http://llvm.org/bugs/show_bug.cgi?id=19225">19225</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code by LTO at -Os (only) on x86_64-linux-gnu (affecting trunk and 3.4)
</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 current clang trunk and 3.4 miscompile the following code when using LTO at
-Os on x86_64-linux-gnu in both 32-bit and 64-bit modes. The generated code
hangs.
This is a regression from clang 3.3.
$ clang-trunk -v
clang version 3.5.0 (trunk 204459)
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 -Os small.c; a.out
$ clang-trunk -flto -O1 small.c; a.out
$ clang-trunk -flto -O2 small.c; a.out
$ clang-3.3 -flto -Os small.c; a.out
$
$ clang-trunk -flto -Os small.c
$ a.out
^C
$ clang-3.4 -flto -Os small.c
$ a.out
^C
$
-------------------------------
int *a, b, c, e, **f = &a;
long long d = -1;
static int *
fn1 (long long p)
{
int g;
if (d < 0)
for (b = 1; b >=0; b--)
{
int h = p;
g = h == 0 ? 0 : 2 % h;
e = g || c;
}
return 0;
}
int
main ()
{
fn1 (a == 0);
return 0;
}</pre>
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