For the following code, gcc since 12 emits the wrong code at -O2.

Compiler explorer: https://godbolt.org/z/reGo6jqGK

$ cat a.c
int printf(const char *, ...);
int h, i = 1, m;
int *j = &i, *k = &i, *l;
short n(short b, short c, int d) {
  short e[] = {71, c, c, 40, 28, 57, 3, 8, 79, 19, c};
  int f = d, a = b;
  short *g = e;
  while (f > 1) {
    a += *g++;
    f -= 2;
  }
  a += *g -= 255;
  return a;
}
int fn2() {
  h = 0;
  for (;; h = 5) {
    int o[4];
    m = 0;
    for (; m < 4; m++)
      o[n(6, 7, 19) - 70 + m] = 6;
    if (h) {
      for (;;) {
        int p = 0;
        if (*k)
          break;
        l = &p;
      }
      *j = o[0];
      return 0;
    }
  }
}
int main() {
  fn2();
  printf("%d\n", i);
}
$
$ gcc-tk -O0 a.c && ./a.out
6
$ gcc-tk -O2 a.c && ./a.out
0
$