[Bug tree-optimization/115547] `(a ^ c) & (a | c)` -> `a ^ c` not done on the gimple/tree level

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115547

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://github.com/llvm/llv
                   |                            |m-project/issues/95946

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note sometimes it can get complex for bool case:
```
bool fn1(bool a, bool b, bool c) {
    return a != c && (b || (c || a));
}

bool fn2(bool a, bool b, bool c) {
    return a != c && (b || c || a);
}
bool fn3(bool a, bool b, bool c) {
    return a != c && (a || b || c);
}
bool fn4(bool a, bool b, bool c) {
    return a != c && (a || c || b);
}
```

The above is from https://github.com/llvm/llvm-project/issues/95946 .

For those we have:
```
  <bb 2> [local count: 1073741824]:
  if (a_3(D) != c_4(D))
    goto <bb 3>; [66.00%]
  else
    goto <bb 4>; [34.00%]

  <bb 3> [local count: 708669600]:
  _8 = c_4(D) | b_5(D);
  _7 = a_3(D) | _8;

  <bb 4> [local count: 1073741824]:
  # iftmp.0_2 = PHI <_7(3), 0(2)>
  return iftmp.0_2;
```

Which really we know that (a|c) will be 1. But maybe that is a different issue
all together.