https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109154
--- Comment #27 from Richard Biener <rguenth at gcc dot gnu.org> --- I've added heuristics to threading to PR109048 but I think it's too strong to reject them. For the testcase in this PR ranger could fix up if it managed to properly propagate the singleton range early. After Jakubs change we're still not doing that for unknown reasons. Jakubs later testcase OTOH looks completely different (and more like PR109048).