https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103388
--- Comment #5 from Jeffrey A. Law <law at gcc dot gnu.org> --- We thread one edge at a time, so we don't know ahead of time how many copies there would be. It could be restructured to go ahead and register these threads, then compute the copy cost on a more global basis. That would allow us to bump up the threshold to register the thread, but still reject things later if the cost appears to be too high. The book keeping necessary to do that would actually be step #0 for the real solution which would be to fix the new copier to coalesce cases where multiple incoming edges thread to the same outgoing edge in a manner similar to what tree-ssa-threadupdate does.
