s := f.Cache.stackAllocState
	if s == nil {
		return new(stackAllocState)
	}
	if s.f != nil {
		f.fe.Fatalf(src.NoXPos, "newStackAllocState called without previous free")
	}
	return s
}

func putStackAllocState(s *stackAllocState) {
	for i := range s.values {
		s.values[i] = stackValState{}
	}
	for i := range s.interfere {
		s.interfere[i] = nil
	}
	for i := range s.names {
		s.names[i] = LocalSlot{}
	}