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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 (that hangs) at -O2 and -O3 on x86_64-linux-gnu"
href="http://llvm.org/bugs/show_bug.cgi?id=21032">21032</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code (that hangs) at -O2 and -O3 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>-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 following code is miscompiled by the current clang trunk on
x86_64-linux-gnu at -O2 and -O3 in the 64-bit mode (but not in the 32-bit
mode).
This is regression from 3.5.0.
Possibly related to PR 21030?
$ clang-trunk -v
clang version 3.6.0 (trunk 218236)
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 -m32 -O2 small.c; a.out
$ clang-trunk -m32 -O3 small.c; a.out
$ clang-trunk -m64 -O1 small.c; a.out
$ clang-3.5.0 -m64 -O2 small.c; a.out
$
$ clang-trunk -m64 -O2 small.c
$ timeout -s 9 10 ./a.out
Killed
$
--------------------------
int a, c, d, e;
long b;
int
fn1 (short p1, int p2)
{
return p2 == 0 || (p1 && p2 == p1);
}
void
fn2 (int p)
{
e = fn1 (p ^ 1, p);
c = e || c;
}
int
main ()
{
for (a = -1; a > -25; --a)
{
int f = a;
unsigned int g = f;
d = g != b;
fn2 (f);
}
return 0;
}</pre>
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