message: Turn this unreachable into a panic with an error message.
diff: @@ -926,7 +926,7 @@ impl Emitter for Assembler {
  match loc {
  Location::GPR(x) => dynasm!(self ; call Rq(x as u8)),
  Location::Memory(base, disp) => dynasm!(self ; call QWORD [Rq(base as u8) + disp]),
  - _ => unreachable!(),
  + _ => panic!("CALL {:?}", loc),
  }
  }
  