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<base href="https://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 in both 32-bit and 64-bit modes."
href="https://llvm.org/bugs/show_bug.cgi?id=25900">25900</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code at -O1 and above on x86_64-linux-gnu in both 32-bit and 64-bit modes.
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</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>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>chengniansun@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The following code is miscompiled by clang-trunk at -O1 and above in both
32-bit and 64-bit modes on x86_64-linux-gnu. It is a regression from clang 3.5.
$: clang-trunk -v
clang version 3.8.0 (trunk 256098)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.2.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
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/4.8.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.2.1
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.6.3
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.7.4
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.8.2
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$:
$: clang-trunk -m32 -O1 small.c -w ; ./a.out
Floating point exception (core dumped)
$: clang-trunk -m32 -O2 small.c -w ; ./a.out
Floating point exception (core dumped)
$: clang-trunk -m32 -O3 small.c -w ; ./a.out
Floating point exception (core dumped)
$: clang-trunk -m64 -O1 small.c -w ; ./a.out
Floating point exception (core dumped)
$: clang-trunk -m64 -O2 small.c -w ; ./a.out
Floating point exception (core dumped)
$: clang-trunk -m64 -O3 small.c -w ; ./a.out
Floating point exception (core dumped)
$:
$: cat small.c
struct S1 {
signed f2;
unsigned f3;
signed f4 : 18;
signed f5 : 1;
unsigned f6;
};
int a, c, f, d = 118;
static char b = -5L, e;
void fn1(struct S1 p1) {}
int main() {
struct S1 g = {6, 9, 7, 0, 2};
fn1(g);
e = d >> 5;
g.f5 = e;
c || ~f;
int h = -g.f5;
a = 7 % (~b / g.f5) - h;
return 0;
}</pre>
</div>
</p>
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