[Bug tree-optimization/117100] [13 regression] ImageMagick miscompiled with -O1 -funswitch-loops

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117100

--- Comment #6 from Sam James <sjames at gcc dot gnu.org> ---
Simplified a bit:
```
int a;

int c (int f) {
  int d = 1;

  for (int e = 0; e < 3; e++) {
    switch (f) {
      case 1:
        d = 0;
      case 2:
        a = 1;
        break;
      case 3:
        __builtin_exit(0);
    }

    switch (f) {
      case 4:
      case 6:
      case 8:
        a = 1;
    }

    if (d)
      __builtin_abort();
  }

  return 1;
}

int main() {
  c(3);
}
```

I can't get it to fail on 14+ though.