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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 by LTO at -O0 and -O1 on x86_64-linux-gnu (both 32-bit and 64-bit modes)"
href="http://llvm.org/bugs/show_bug.cgi?id=19078">19078</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code by LTO at -O0 and -O1 on x86_64-linux-gnu (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>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
and -O1 (but not at -Os and above) on x86_64-linux-gnu (in both 32-bit and
64-bit modes).
$ clang-trunk -v
clang version 3.5.0 (trunk 203239)
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 small.c; a.out
-1
$ clang-trunk -flto -Os small.c; a.out
-1
$
$ clang-trunk -flto -O0 small.c; a.out
0
$ clang-trunk -flto -O1 small.c; a.out
0
$
---------------------------------
int printf (const char *, ...);
int a, b, c, d = 1, e, g, h;
short f;
int
fn1 (int p1, int p2)
{
return -p2 < 0 ? 0 : p2;
}
int
fn2 ()
{
return b = 0;
}
void
fn3 (int p)
{
int i, j = d = 0;
i = 1 ? 1 : 0;
f = j || j || 0 > j ? 0 : j;
if (!(1 & i && f))
{
if (g)
;
for (g = 0; g != 1; g++)
{
g || fn1 (fn2 (), p);
if (!d)
{
e = g || a;
break;
}
}
for (h = -1; c >= 0; c = h)
if (g)
break;
}
}
int
main ()
{
fn3 (1);
printf ("%d\n", c);
return 0;
}</pre>
</div>
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