https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61171
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- it's a matter of association being "unfortunate" or vector reduction detection being too simplistic. # prephitmp_21 = PHI <pretmp_20(4), _9(7)> ... _2 = pretmp_18 + prephitmp_21; _9 = _2 - _6; needs to be associated as _2 = pretmp_18 - _6; _9 = prephitmp_21 + _2; usually reassoc is responsible for ensuring this but given its last iteration is before LIM pulls out the global it has no chance to fix things up. One fix would be to split out enough from reassoc into a worker that can be called from vectorization or to run LIM before reassoc.
