Comedian-musician Steve Martin and director Carl Reiner have made some good movies individually, but when they teamed up with Lily Tomlin on 1984’s “All of Me,” the result was nothing more than mediocre, 1960s-style slapstick. Harried lawyer (Martin) and snobby client (Tomlin) suddenly inhabit the same body due to a seance snafu. Split-personality hijinks ensue. Two things save this film: Martin is such a master of physical comedy he can actually do it for more than two minutes without it becoming tiresome; and Tomlin’s character (and performance) becomes less cliche and more interesting once the plot transitions to a rom-com.