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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 --- - wrong code at -O3 on x86_64-linux-gnu (affecting all clang versions)"
href="http://llvm.org/bugs/show_bug.cgi?id=17906">17906</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -O3 on x86_64-linux-gnu (affecting all clang versions)
</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 by the current clang trunk and older versions
on x86_64-linux-gnu at -O3 in both 32-bit and 64-bit modes.
$ clang-trunk -v
clang version 3.4 (trunk 194528)
Target: x86_64-unknown-linux-gnu
Thread model: posix
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 -O2 small.c; a.out
1
$ clang-trunk -O3 small.c; a.out
0
$ clang-3.3 -O3 small.c; a.out
0
$ clang-3.2 -O3 small.c; a.out
0
$ clang-3.1 -O3 small.c; a.out
0
$ clang-3.0 -O3 small.c; a.out
0
$ clang-2.9 -O3 small.c; a.out
0
$
$ gcc-trunk -O3 small.c; a.out
1
$ icc -O3 small.c; a.out
1
$
$
--------------------------------
int printf (const char *, ...);
int *a, b, **e = &a, g;
long c;
char d;
int
fn1 (int p)
{
return p;
}
static int
fn2 (int *p1, long *p2)
{
char *f = &d;
fn1 (*p2);
*f = *p1;
return 0;
}
void
fn3 ()
{
fn2 (0, 0);
}
int
main ()
{
for (b = 0; b < 1; b = 1)
{
*e = &g;
*a = 1;
fn2 (&g, &c);
}
printf ("%d\n", d);
return 0;
}</pre>
</div>
</p>
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