[Bug tree-optimization/91540] missed value-replacement in phiopt

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91540

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
In summary, clang is trying to produce xor always for similar value reductions
(or still branches) while GCC produce plus and minus; though producing xor or
ior might lead to better code in general.