[Bug tree-optimization/123113] factor_out_conditional_operation could be improved to handle `EDGE_COUNT (merge->preds) != 2`

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123113

--- Comment #14 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Retesting this set of patches we have `gcc.dg/pr68435.c` failure. But I think
this is a false positive. In that we get the commonization on the tree level
and gcc produces a?1:-1 now and then that is ok for ifcvt. So just needing to
disable phiopt for the testcase.

I will finish up this set of patches once the load commonization happens in
phiopt.