<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/57184>57184</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang crashes 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>Labels</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          zhendongsu
      </td>
    </tr>
</table>

<pre>
    It appears to be a recent regression.

Compiler Explorer: https://godbolt.org/z/TEqGhcT7r

```
[507] % clangtk -v
clang version 16.0.0 (https://github.com/llvm/llvm-project.git de6fd169715764f0401d8580b64c11fda45101e1)
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/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
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/11
Candidate multilib: .;@m64
Selected multilib: .;@m64
[508] % 
[508] % clangtk -O2 small.c; ./a.out
[509] % 
[509] % clangtk -O3 small.c
fatal error: error in backend: Instruction Combining seems stuck in an infinite loop after 100 iterations.
clang-16: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 16.0.0 (https://github.com/llvm/llvm-project.git de6fd169715764f0401d8580b64c11fda45101e1)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/opfuzz/bin
clang-16: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-16: note: diagnostic msg: /tmp/small-3fdae0.c
clang-16: note: diagnostic msg: /tmp/small-3fdae0.sh
clang-16: note: diagnostic msg: 

********************
[510] % cat small.c
int a, b, c, d, e;
int f() { return a; }
void g() {
  int *h = &b, *i = &b, *j = &b;
  while (a) {
    d = 1;
    break;
  }
  *h ^= e = 2;
  for (; e; e--) {
    c = 0;
    for (; c <= 50; c++) {
      if (*j)
        continue;
      *i ^= f();
    }
  }
}
int main() {
  g();
  return 0;
}
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzlV0tv4zYQ_jXyZWBBb9sHHxLHzgYImsXGix4LihzJ3EiiS1JJml_fIWU7SrIo2ibppYFC8THzzXCG81EulfhjeWWB7ffItAGroERgoJFjZ-lVazRGqi4MoosgOhvalWr3skEN68d9ozTqID2DnbV7Q50g2dBTK1GqxoZK1zR6ov_t-vfLHd_O9BgpKKLDMwzz8zyaBfkFBEkOvGFdbe9gej-s-jHco3YOQVyEURiR4PyVZWl3fRly1dKgae6Pr-leqx_IbUgCILCoRFwsZnE-K7IqyqJYzPN5VBYZj-NKsCyPoxjjIFkMtrdM12jdPh_nxW9FNu27u049dNNGdv3jtO76g9xOIxPQKoGNk94rIx-HpavOWNY0KC6kD5jzS3HW0Nv0T9NjX-2r_skFrJTdoLhRfSeAs05IwSzC5WoFcgBjlkJxAOuNdpCydEHgnFpZzIuRg8lm_k7Aw97HkHH0CZjxx2MWnwAZ5uEn7H72CZCf4-nhON1iQ3WF4kNyvjp51vaNlU6LUMIgPQ-yqC2yVyb_SsizyfzIJj-bOzHMTQKmJbdDThgElGxYqHo70ln8BGfxFic94XixilEwALVWvuR9h0IEJeN32Ak352hB99zFC4hYqeolsZxBbA0Y2_M7J886aitaorg0Su2BVZb4N44ioCnto23CEU1O4-Jk0HUG7qy06iy6_Ku2pUBDxYjHBTwQZwI-EjFyIi6YeVrtDRL1uiuBnCHz90RQPqtHTvy_8vE4wJ2y6N5CsrpTxkoOrak93HBOknc8o4vy6_X67HYNZ9vt2eoLbL-sYXNzfX3z69Uvl7C5ul7fwvbGT59_v4Rv668337YuA4OuRoo1p4ucUm1UrzlSlgzFEtwZYMYoLpmrJt13YLiWe3sS0O7Acb_K7Anyb4Yg2dh27-LpamKaUh4xOpbGeyDM7l9k4qPyQZVPl96x8pl9WfGSPptYkKygdA13jXANOnI6SVQUXxfeYHZOH1m211TijnmC2cUgdK-kgPpZapgFcMrkyg6C1DlQeCs0IV9P_HieSE_aDzsqd1ei7BUsgPDy8UgYoKTauRvNnLyDgw_52imhV01GghWxnPOddoS-mU7fGOReK3phcKTnlldOIo_8MEjO_fMKhSJSeRXa8Ykc4PDHie2IDvCFDTiEa_D9kIgXEuNtHrunjktAy4gK3qSmfgN1yOzzHp_hjt-9E1zGRREVi2RGA7FMxSJdsImVtsHlQLBcM7NDQ-Xn7xei2jfXJx3y__ammfS6Wf4znnffo8b0SLSyyWfxPJvslkT0LM_momJ5KWbFPM5zliVZjBgtWJylk4aV2Jgl1RwV3EQukyhJonlcJGmapItQxBX9UBEYp4jJgkd0-yMlpwmdYffbY6KX3oeyrw0tNtJY87xIzCfrDvGIz3q7U3r5tKOAqa42_cR7vPTu_gleVtrP">