[Bug tree-optimization/112104] loop of ^1 should just be reduced to ^(n&1)

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112104

--- Comment #5 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Andrew Pinski from comment #4)
> Fixed via r14-5428-gfd1596f9962569afff6c9298a7c79686c6950bef .

Note, my patch only handles constant tripcount for XOR, but not do the
transformation when tripcount is variable.