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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 -O2 on x86_64-linux-gnu (affecting trunk and 3.4)"
href="http://llvm.org/bugs/show_bug.cgi?id=19670">19670</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -O2 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 following code is miscompiled by the current clang trunk and clang 3.4 on
x86_64-linux-gnu at -O3 (in both 32-bit and 64-bit modes). The generated code
hangs.
This is a regression from 3.3.
$ clang-trunk -v
clang version 3.5.0 (trunk 208085)
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-3.3 -O2 small.c; a.out
$
$ clang-trunk -O2 small.c
$ a.out
^C
$ clang-3.4 -O2 small.c
$ a.out
^C
$
----------------------------------------
int a, b, d, e, f, g, h, i, k, l, m, n;
short c;
int
fn1 (int p1, int p2)
{
return (p1 && p1 > p2) || p2 ? p1 : p1 + 1;
}
void
fn4 (int p)
{
for (; p; p++)
if (c)
for (; d;)
f = 0;
}
static unsigned int
fn3 (short p)
{
if (k)
for (; g;)
if (e)
l = p;
if (p)
for (; m; ++m)
if (c)
for (; d;)
;
n = b ? 0 : a;
fn4 (p ^ (n > 0));
return c;
}
static char
fn2 ()
{
int j = -9;
for (; j; j = fn1 (j, 0))
{
for (; i;)
fn3 (j);
if (j)
for (; e;)
;
}
return 0;
}
int
fn5 ()
{
fn2 ();
for (h = 0; h; h = fn3 (0))
;
return 0;
}
int
main ()
{
fn5 ();
return 0;
}</pre>
</div>
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