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<base href="https://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 -O3 on x86_64-linux-gnu (in both 32-bit and 64-bit modes)"
href="https://llvm.org/bugs/show_bug.cgi?id=28307">28307</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -O3 on x86_64-linux-gnu (in both 32-bit and 64-bit modes)
</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>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The following code is miscompiled by the clang trunk at -O3 on x86_64-linux-gnu
in both the 32-bit and 64-bit modes.
This is a regression from 3.8.x.
It appears different from PR 28297.
$ clang-trunk -v
clang version 3.9.0 (trunk 273774)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
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/4.8.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$
$ clang-trunk -O2 small.c; ./a.out
4
$ clang-3.8 -O3 small.c; ./a.out
4
$
$ clang-trunk -O3 small.c
$ ./a.out
0
$
-----------------------------------------------
int a, b, *c, e, f, g = 1, h, k, m, n, p;
static int **d = &c, j = 1;
short l = 1;
static void
fn1 (int p1)
{
char t;
int *r;
unsigned s;
if (g)
{
int u, **v = &c;
*d = &b;
**d = h == p1;
for (; p1 < 6; p1++)
for (t = 0; t < 5; t += 4)
{
m = 0;
if (**v ? ~0 % **v : ~0)
{
if (l)
*v = &p;
}
else
return;
u = 0;
for (; u < 1; u++)
r = &b;
*v = r;
s = j ? j : a;
if (**v % s & 10)
return;
}
*c = 4;
}
n = b;
f = 0;
}
void
fn2 ()
{
fn1 (1);
while (k)
e++;
j = 0;
}
int
main ()
{
fn2 ();
__builtin_printf ("%d\n", b);
return 0;
}</pre>
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