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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 at -O1 and above on x86_64-linux-gnu"
href="http://llvm.org/bugs/show_bug.cgi?id=21582">21582</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -O1 and above 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 current clang trunk miscompiles the following code at -O1 and above on
x86_64-linux-gnu in both 32-bit and 64-bit modes.
This also affects 3.5.0, and is a regression from 3.4.x.
$ clang-trunk -v
clang version 3.6.0 (trunk 220897)
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/4.6.4
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-3.4.2 -O1 small.c; a.out
1
$
$ clang-trunk -O1 small.c; a.out
0
$ clang-3.5.0 -O1 small.c; a.out
0
$
--------------------------------
int printf (const char *, ...);
int a, b, c, e, k, l;
struct
{
int f1;
} d;
void
fn1 ()
{
if (d.f1)
for (c = 0; a;)
for (; l;)
;
}
int
fn2 ()
{
for (; b < 1; b++)
for (; k; k++)
fn1 ();
return 0;
}
int
fn3 ()
{
int g = 0, h;
int i[1][1] = { {1} };
for (;;)
{
b = 0;
for (; g < 1; g++)
h = i[0][g] != fn2 ();
if (++e)
return 0;
g = h;
}
}
int
main ()
{
fn3 ();
printf ("%d\n", b);
return 0;
}</pre>
</div>
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