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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"
href="http://llvm.org/bugs/show_bug.cgi?id=17794">17794</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -O2 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>LLVM Codegen
</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 (the generated code hangs) by the current
clang trunk on x86_64-linux-gnu at -O2 in both 32-bit and 64-bit modes.
This is a regression from clang 3.3.
$ clang-trunk -v
clang version 3.4 (trunk 193964)
Target: x86_64-pc-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 -Os small.c; a.out
$ clang-3.3 -O2 small.c; a.out
$
$ clang-trunk -O2 small.c
$ a.out
^C
$
$ gcc-trunk -O2 small.c; a.out
$ icc -O2 small.c; a.out
$
---------------------------
int a, b, c, d, f;
char e;
int
fn1 (int p1, int p2)
{
return p1 > 0 || 1 < -p2 ? p1 : p1 + 1;
}
int
fn2 (unsigned short p1, unsigned short p2)
{
return p1 - p2;
}
void
fn3 (int p1, int p2)
{
for (; p1 < 13; ++p1)
{
e = p1 * 2;
if (e < a && a)
if (p2 ^ b)
c = 0;
}
}
static int
fn4 (short p)
{
for (d = 1; d;)
{
int h = -7;
h = fn2 (p, h);
if (h)
return 0;
fn3 (0, p);
}
fn3 (0, 0);
return 0;
}
static int
fn5 ()
{
int g = -19;
for (; g; g = fn1 (g, 0))
{
for (; f; f++)
fn4 (g);
if (g)
b = 0;
}
return 0;
}
static int
fn6 ()
{
fn5 ();
fn4 (0);
return 0;
}
int
main ()
{
fn6 ();
return 0;
}</pre>
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