[Bug tree-optimization/91882] boolean XOR tautology missed optimisation

[sucicf1 at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91882

--- Comment #5 from Ivan Sučić <sucicf1 at outlook dot com> ---
I have added in match.pd a simplify. But for unknown reason it doesn't get
applied.  Anybody knows why?