https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94043
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> --- OK, so it's indeed vectorizable_live_operation not paying attention to loop-closed SSA form. What it should do before building the lane extract is create a _new_ loop-closed PHI node for the vectorized def (vec_lhs), and then demote the loop-closed PHI node for the scalar def (lhs) which should _always_ exist to a copy. So from loop; # lhs' = PHI <lhs> go to loop; # vec_lhs' = PHI <vec_lhs> new_tree = BIT_FIELD_REF <vec_lhs', ...>; lhs' = new_tree; I think you can assert that the block of the loop-closed PHI (single_exit()->dest) always has a single predecessor, otherwise things will be more complicated. Can you try rework the code in this way? If that's too much just tell me and I'll take care of this.
