[Bug tree-optimization/109959] `(a > 1) ? 0 : (a == 1)` is not optimized when spelled out at -O2+

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109959

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> This is basically PR 102138 .

Except it works at -O1 because the cast is pushed out of the phi by phiopt but
the cast is the same as a & 1 here :(.

For comment #0 we could just match this for unsigned type
a_2(D) > 1 ? 0 : a_2(D) == a_2(D) <= 1 ? a_2(D) : 0 -> (unsigned)(a == 1)

For comment #3 we need to pattern match this now:
  _7 = (_Bool) a_6(D);
  _9 = a_6(D) <= 1;
  _10 = _7 & _9;