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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - clang crashes on valid code at -O3 on x86_64-linux-gnu: fatal error: error in backend: Instruction Combining seems stuck in an infinite loop after 100 iterations"
href="https://bugs.llvm.org/show_bug.cgi?id=50594">50594</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang crashes on valid code at -O3 on x86_64-linux-gnu: fatal error: error in backend: Instruction Combining seems stuck in an infinite loop after 100 iterations
</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>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>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>zhendong.su@inf.ethz.ch
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, pengfei.wang@intel.com, spatel+llvm@rotateright.com
</td>
</tr></table>
<p>
<div>
<pre>[512] % clangtk -v
clang version 13.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
c2ab3d2c85c8af4483f05d8bb702891cd3682969)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/opfuzz/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
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/7.5.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
[513] %
[513] % clangtk -O2 small.c; ./a.out
[514] %
[514] % clangtk -O3 small.c
fatal error: error in backend: Instruction Combining seems stuck in an infinite
loop after 100 iterations.
clang-13: error: clang frontend command failed with exit code 70 (use -v to see
invocation)
clang version 13.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
c2ab3d2c85c8af4483f05d8bb702891cd3682969)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/opfuzz/bin
clang-13: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-13: note: diagnostic msg: /tmp/small-d1ac30.c
clang-13: note: diagnostic msg: /tmp/small-d1ac30.sh
clang-13: note: diagnostic msg:
********************
[515] %
[515] % cat small.c
int printf (const char *, ...);
int d, f, g, h;
static int e = 1;
int main() {
long long l = 0;
int m = 1, i, j;
for (i = 0; i < 4; i++)
for (j = 0; j < 10; j++) {
int n;
h = m;
n = g = d * h * l >> f;
m = e * f;
l = ~n & d * m & f;
if (!e) {
printf("%d\n", g);
continue;
}
if (h < 1) {
printf("%lld\n", l);
continue;
}
f = m = h;
l = n;
}
for (e = 0; e < 2; e++)
;
return 0;
}</pre>
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