addVarSlot := func(name *ir.Name, typ *types.Type) {
		sl := LocalSlot{N: name, Type: typ, Off: 0}
		rval.Vars = append(rval.Vars, name)
		rval.Slots = append(rval.Slots, sl)
		slid := len(rval.VarSlots)
		rval.VarSlots = append(rval.VarSlots, []SlotID{SlotID(slid)})
	}

	// Make an initial pass to populate the vars/slots for our return
	// value, covering first the input parameters and then (if needed)