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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 by LTO at -O0 on x86_64-linux-gnu in 64-bit mode"
href="http://llvm.org/bugs/show_bug.cgi?id=19073">19073</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code by LTO at -O0 on x86_64-linux-gnu in 64-bit mode
</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 miscompiles the following code when using LTO at -O0 on
x86_64-linux-gnu in 64-bit mode (but not 32-bit mode).
$ clang-trunk -v
clang version 3.5.0 (trunk 203119)
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 -O0 f.c main.c
$ a.out
1
$ clang-trunk -flto -m32 -O0 f.c main.c
$ a.out
1
$ clang-trunk -flto -m64 -O1 f.c main.c
$ a.out
1
$
$ clang-trunk -flto -m64 -O0 f.c main.c
$ a.out
0
$
$
$ cat f.c
extern int a, b, d, e, g;
extern long f;
static int
fn1 (int p)
{
return b ? 0 : p;
}
int
fn2 ()
{
int h = 1;
e = d + 1;
if (fn1 (e < 0))
for (h = 0; h;)
;
else
{
int i = 0, j = 0;
g = a ? 0 : i;
f = g;
if (f || j || j || f >> j)
;
for (d = 1; d; d = (char) d + 1)
;
}
return h;
}
$ cat main.c
extern int printf (const char *, ...);
extern int fn2 ();
int a, b, c, d, e, g, k;
long f;
int
main ()
{
k = fn2 ();
if (k)
c = 1;
printf ("%d\n", c);
return 0;
}</pre>
</div>
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