fallthrough
				case ir.PPARAM, ir.PAUTO:
					n.SetUsed(true)
				}
			}
		}
	}

	var mls *liveness.MergeLocalsState
	var leaders map[*ir.Name]int64
	if base.Debug.MergeLocals != 0 {
		mls = liveness.MergeLocals(fn, f)
		if base.Debug.MergeLocalsTrace > 0 && mls != nil {
			savedNP, savedP := mls.EstSavings()

// items larger than what CanSSA would allow (approximateky, we disallow things
// marked as open defer slots so as to avoid complicating liveness
// analysis.
func IsMergeCandidate(n *ir.Name) bool {
	if base.Debug.MergeLocals == 0 ||
		base.Flag.N != 0 ||
		n.Class != ir.PAUTO ||
		n.Type().Size() <= int64(3*types.PtrSize) ||
		n.Addrtaken() ||
		n.NonMergeable() ||
		n.OpenDeferSlot() {
		return false
	}
	return true

// argument is a slice of *Nodes.
func (lv *liveness) pointerMap(liveout bitvec.BitVec, vars []*ir.Name, args, locals bitvec.BitVec) {
	var slotsSeen map[int64]*ir.Name
	checkForDuplicateSlots := base.Debug.MergeLocals != 0
	if checkForDuplicateSlots {
		slotsSeen = make(map[int64]*ir.Name)
	}
	for i := int32(0); ; i++ {
		i = liveout.Next(i)
		if i < 0 {
			break
		}
		node := vars[i]
		switch node.Class {