<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 - Infinite loop at -O2 and above at compile-time on clang 12.0.x to trunk version"
href="https://bugs.llvm.org/show_bug.cgi?id=51657">51657</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Infinite loop at -O2 and above at compile-time on clang 12.0.x to trunk version
</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>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>haoxintu@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Hi all.
The following test program makes clang 12.0.x to trunk version hang on -O2 and
above.
$cat small.c
#include <stdint.h>
int a,b,c;
void d(int e) {
int8_t *f;
int16_t g;
int32_t i = &a;
uint16_t *j;
int8_t *k = &c;
int16_t l = 246;
uint64_t m;
int8_t **n = &k;
int64_t o;
int16_t *p;
for (; p;) {
int64_t *q = o;
for (*q = 5; *q; *q += 1)
if (*k = b)
for (*j = 3; *j; j++) {
int8_t r;
o = r;
}
for (; p <= 2; p++)
s:
l = 1;
}
g = m = e;
uint64_t v;
int32_t **u = &i;
uint64_t t = &v;
f = *u;
*f = c = l;
v = (g ?: (**u = m << **n)) == *f;
for (; i <= 8; *f = t)
;
goto s;
}
$clang -w -O2 -m32 small.c
//endless compiling, same as -O3 and -Os
$time clang -c -w -O1 -m32 small.c
real 0m0.059s
user 0m0.028s
sys 0m0.031s
The clang version I used:
clang version 14.0.0 (<a href="https://github.com/llvm/llvm-project">https://github.com/llvm/llvm-project</a>
022538f2764a255bd2c0da3a247791e764933a93)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/haoxin/haoxin-data/compilers/llvm-project/build/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
Reproduced in Godbolt: <a href="https://godbolt.org/z/ndxn1cT91">https://godbolt.org/z/ndxn1cT91</a>
Thanks,
Haoxin</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>