https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103544
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> --- Hmm, or rather the reduction path with chain starts in midst of the cycle because it has a leading conversion embedded which we don't represent. But the reduction path detection fails so we instead discover a SLP reduction but now with the "wrong" leading stmt. We'd have to reverse engineer the original which can be quite complicated (see how vectorizable_reduction walks the chain). For an initial fix that can be backported do simple.
