https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86489
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
gimple *phi = SSA_NAME_DEF_STMT (b_11);
if (gimple_code (phi) != GIMPLE_PHI
|| (gimple_assign_lhs (and_stmt)
!= gimple_phi_arg_def (phi, loop_latch_edge (loop)->dest_idx)))
return false;
this may fail if the PHI in question is not the correct one in which case
it may not have the argument at the latch dest_idx. Try first verifying
that the loop latch destination is indeed gimple_bb (phi).
