[Bug tree-optimization/123065] out of ssa should handle degenerate_phis instead of "optimized"/final_cfgcleanup

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123065

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
This is to reduce the number of edge copies by inserting a forwarder where a
common edge copy can be inserted.