RegAlloc []Location

	// temporary registers allocated to rare instructions
	tempRegs map[ID]*Register

	// map from LocalSlot to set of Values that we want to store in that slot.
	NamedValues map[LocalSlot][]*Value
	// Names is a copy of NamedValues.Keys. We keep a separate list
	// of keys to make iteration order deterministic.
	Names []*LocalSlot
	// Canonicalize root/top-level local slots, and canonicalize their pieces.

	// slots that is type-insenstitive.
	sc := newSlotCanonicalizer()
	for _, sl := range f.Names {
		sc.lookup(*sl)
	}

	// Add slot -> value entry to f.NamedValues if not already present.
	addToNV := func(v *Value, sl LocalSlot) {
		values, ok := f.NamedValues[sl]
		if !ok {
			// Haven't seen this slot yet.
			sla := f.localSlotAddr(sl)
			f.Names = append(f.Names, sla)
		} else {
			for _, ev := range values {

		return
	}
	loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
	values, ok := s.f.NamedValues[loc]
	if !ok {
		s.f.Names = append(s.f.Names, &loc)
		s.f.CanonicalLocalSlots[loc] = &loc
	}
	s.f.NamedValues[loc] = append(values, v)
}

// Branch is an unresolved branch.
type Branch struct {
	P *obj.Prog  // branch instruction