https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93637
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The problem is that with -mavx -mno-avx2, we have vcondv4div4df optab, but not vcondv4div4di. Before fre4 we have: vect_cst__5 = { 0.0, 0.0, 1.0e+0, 0.0 }; ... _55 = &ev[0] + 32; MEM <vector(4) double> [(double *)_55] = vect_cst__5; ... vect_cst__49 = { 0.0, 0.0, 0.0, 0.0 }; ... vectp_ev.9_29 = &ev + 32; ... vect__1.11_77 = MEM <vector(4) double> [(double *)vectp_ev.9_29]; ... _80 = VEC_COND_EXPR <vect_cst__49 == vect__1.11_77, ivtmp_2, _28>; which fre4 optimizes into: _80 = VEC_COND_EXPR <{ -1, -1, 0, -1 }, { 5, 6, 7, 8 }, _28>; but with the comparison in VEC_COND_EXPR simplified into a constant all traces of the V4DF are gone, and this is after the last veclower pass.