[Bug rtl-optimization/77855] [7 Regression] wrong code at -O3 on x86_64-linux-gnu (in both 32-bit and 64-bit modes)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77855

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Testcase failing at -O2:

int a, b = 1, c, e, f, g, k, m, n, o;
char d, h, i, j, l;
char res[2];

void __attribute__ ((noinline,noclone)) fn2 ()
{
  d = 2;
}

void fn3 ()
{
  for (;;)
    {
      for (; b; b--)
        {
          fn2 ();
          if (e)
            j = 1;
          if (f)
            L1:
                k = j | (a & l);
          for (;;)
            {
              __builtin_snprintf (res, 2, "%d\n", d);
              if (d)
                break;
              for (; o; o--)
                for (; n;)
                  for (; m; m++)
                    ;
              goto L1;
            }
        }
      g = h;
      c = i;
      break;
    }
}

int main ()
{
  fn3 ();
  if (res[0] != '2')
    __builtin_abort ();
  return 0;
}