<html>
<head>
<base href="https://llvm.org/bugs/" />
</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 --- - wrong code bug"
href="https://llvm.org/bugs/show_bug.cgi?id=27392">27392</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code bug
</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>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>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>regehr@cs.utah.edu
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, sanjoy@playingwithpointers.com
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>regehr@hawking:~/test/reduce_wrong_333190$ clang small.c ; ./a.out
-65536
regehr@hawking:~/test/reduce_wrong_333190$ gcc small.c ; ./a.out
-65536
regehr@hawking:~/test/reduce_wrong_333190$ clang small.c -O ; ./a.out
0
regehr@hawking:~/test/reduce_wrong_333190$ cat small.c
int printf(const char *, ...);
short a;
volatile unsigned b;
int main() {
short *c = &a;
lbl:
b--;
(*c)--;
if (a)
goto lbl;
printf("%d\n", b);
return 0;
}
regehr@hawking:~/test/reduce_wrong_333190$ clang -v
clang version 3.9.0 (trunk 266564)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/regehr/llvm-install/bin
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/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
Sanjoy this looks like it might be an instance of the SCEV issue you already
know about, but I wanted to make sure, since this example came up
independently.</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>