This one I'm less sure about. In 14.sml from the regression directory, why can't we eliminate the constant equality test? The CPS has val global_13 = A_0 () val global_14 = B_0 () fun L_42 () = let val x_7 = Env_0 () val x_6 = Ref_assign (x_1, x_7) val x_5 = MLton_eq (global_13, global_14) in case x_5 of false => L_32 | true => L_31 end