<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - LLVM miscompiles long double to unsigned long long conversion"
href="https://bugs.llvm.org/show_bug.cgi?id=38289">38289</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>LLVM miscompiles long double to unsigned long long conversion
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</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>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>benny.kra@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>$ cat fp.c
long double l = 10240000000000000256.000000L;
int main() {
__builtin_printf("%llu\n", (unsigned long long)l);
}
$ clang -O0 fp.c && ./a.out
10240000000000000256
$ clang -O1 fp.c && ./a.out
10239999935508381696
This only happens when no ssse3 is available. This started failing with
r329339,
but the bug is probably older. What happens is that instructions get scheduled
over a x87 control word store.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>