[Bug tree-optimization/122845] `a ^ CST ^ CST` is sometimes not folded at the gimple level (casts)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122845

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Another testcase this time without a CST and with `&` instead.
```
int f(signed char a, int  b)
{
  int aa = a;
  int bb = b;
  aa &= bb;
  signed char t = aa;
  aa = t;
  aa &= bb;
  t = aa;
  return t;
}
```