<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/113240>113240</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Compiler in infinite loop after 6fd229a
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    One of our internal tests started to time out and when I looked into it, the test actually appears to be hitting an infinite loop in the compiler. I was able to bisect the cause back to commit 6fd229a655f521a9f58d40c671e5cab4ea3ea87b. Note that in #109215 it mentions ec78f0da0e9b1b8e2b2323e434ea742e272dd913 as a possible fix, but I tried that and the compiler still seems to be stuck in an infinite loop.

Consider the following code:
```c++
long b;
struct {
  unsigned long a : 43;
} c;
void d() {
  long e = b & b - 1, f = c.a = e;
  c.a = 0;
  volatile long g(~f & g);
}
```

If compiled with optimizations and the BMI attributes with a compiler that does not include 6fd229a655f521a9f58d40c671e5cab4ea3ea87b, the compilation succeeds quickly:
```
$ time ~/src/upstream/b9cae45b63bc9c44521cc28b4a381afec6181f54-linux/bin/clang -c -O2 -mbmi repro.cpp -o repro.o

real    0m0.046s
user 0m0.012s
sys     0m0.035s
```
However, the same compilation with a compiler built from ec78f0da0e9b1b8e2b2323e434ea742e272dd913 still seems to be stuck in an infinite loop somewhere:
```
$ time /home/dyung/src/upstream/ec78f0da0e9b1b8e2b2323e434ea742e272dd913-linux/bin/clang -c -O2 -mbmi repro.cpp -o repro.o
^C

real    5m6.955s
user 5m6.594s
sys     0m0.337s
```
Godbolt link: https://godbolt.org/z/7deanqrnn
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJykVc-So7gPfhrnokoKBA5w4DDT_ctv-7A7z-A_IvG2sRnbdKbnMM--ZUh6stkcZmurKCjJ0mf5-yQsYjRHR9Qz_pnx542Y08mHXr_P7riRXr_3XxyBH8DPAYxLFJywkCimCDGJkEhD8pDMSODnBMJpOJ_IwQtY719J5yQPJjF8gnSiJRWESrOw9h3ENJEIMUNIgpNJybgjCAfGDcaZRBllAuOWXOXHyVgKO3iBs4ggpKUl1URSaQ0RcySQQr3mBeXH0STYDxqxE3vOB46l6Abe6rpQ-6YkroSsSVQk2kbu4A-fCNJJpLwlw6osOiw5mAQjuWS8i0CqaYdCi4I6WcqWUGKFFdVVTaKpkbBBrbuyglwgTD5Gk8sczLdMgZwTvEAKJvOW98mE3Z4NYjLWQiQar7TENKvXXNA9LztWPLPi0_p-8i4aTWFBG7y1_py5VF4Tqy4xbF-sj2L4OT-L13p3BMmqixlTmFUC1lxsgNktTaJhiRTAqk9QVx8JrHkG9WG9eaNBM2wZdrcgSy4Bq55BAsM9SNhCmTkZFqfaieVLH0jw4StufG_eimQsrYBHhu2PYcE7Muxua7o78i1XL8OVbw1nk07gp2RG812sEl81-fz7C4iUgpFzorhGip9KLfppTxGczw2j7Kzpl5vtOhAr3LIzxFkpIh3h62zUq33_p3AXE-t15H4wPMSgGB7mKaZAYmR4kJ0SVHO5r6TqVF1zLJXCVtaiaksxkNqXbTnwemuNm7_lBOMYHpQV7ghbBdsvCNtRjgYCTcHv1DTB1l8Mf8tjIGEBAIqx2BX1Pq7eOVJYXSVeXPE9wkdgxePDU_3mz_RG4UpMFOPf2bnnX87GJhiCH399KP_FdEH0I51PFB7Mz50MDA8nPxLDw_LjfCTKr1b4n0Th_3t6JA8f97uO81t5sot39QN5qqp5LM__vZbeJrDGveY_wCmlKWZq8MDwcFxXdz7k439neGg0Cfc1OLfRfaW7qhMb6ssGO8732OHm1A-4b1EXUg9N3QrdtJ0cmqIdyqHCtqybjemxwLosEIuibEvccVHremgaVFwOJeesLmgUxu6sfRvz3hsT40x9WVZYFxsrJNm43G2Ijs6wrDLEfNWFPidt5XyMrC6siSn-hEkmWeqfrq1m7ntDDInCddY3c7D9HR0mnWa5Uz5rn1Evn-0U_J-kEsPDUktkeLgU-9bjXwEAAP__v_9OwQ">