<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 - clang miscompiles with "-newgvn" at -O2 on valid code"
href="https://bugs.llvm.org/show_bug.cgi?id=38214">38214</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang miscompiles with "-newgvn" at -O2 on valid code
</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>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>helloqirun@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>It happens at -O2 and -Os only. I have also tested r334040 and it miscompiles
as well.
$ clang-trunk -v
clang version 7.0.0 (trunk 337366)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
$ clang-trunk abc.c ; ./a.out
-16
$ clang-trunk -mllvm -enable-newgvn -O3 abc.c ; ./a.out
-16
$ clang-trunk -mllvm -enable-newgvn -O2 abc.c ; ./a.out
0
$ cat abc.c
int printf(char *, ...);
char a, b;
char c[1];
int d, e;
char(f)(char g, char h) { return g + h; }
int __attribute__((noinline)) i(long g) { return g ? 1 : 0; }
int main() {
char j = 0;
for (; j != 15; j = f(j, 5)) {
a = 0;
for (; a < 11; ++a)
if (a == b && j) {
e = 0;
for (; e < 8; e++)
if (i((long)c))
--d;
}
}
printf("%d\n", d);
}</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>