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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Infinite loop at -Os"
href="https://bugs.llvm.org/show_bug.cgi?id=49556">49556</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Infinite loop at -Os
</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.
This small and valid code, small.c, makes Clang trunk hung on at compile time
at -Os. It seems that there exists an infinite loop. Note that this issue
exists in all clang-10.0.1 upwards and clang-6.0.1 downwards versions.
$cat small.c
#include <stdint.h>
int a, b;
int16_t c;
void d() {
uint16_t *e = 0;
int32_t f = 0;
uint16_t **g = &e;
for (; b; b++) {
int64_t *i = a;
for (; i; i++)
*g = &f;
}
{
int16_t *g = &c;
int16_t **j = &g;
for (; *e;)
;
*g && (**j = 0);
for (;; *e %= c)
;
}
}
$clang -v
clang version 13.0.0 (<a href="https://github.com/llvm/llvm-project">https://github.com/llvm/llvm-project</a>
590ac0a26af4c9f63d5564be8c13b12d409a7fd9)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir:
/home/haoxin/haoxin-data/dut-research/compilers/llvm-project/build-20210310/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Candidate multilib: .;@m64
Selected multilib: .;@m64
Reproduced in godbolt: <a href="https://godbolt.org/z/nfsona">https://godbolt.org/z/nfsona</a>
Thanks,
Haoxin</pre>
</div>
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