t.edges = append(t.edges, Edge{f.Entry, 0})
	t.defUse = make(map[*Value][]*Value)
	t.defBlock = make(map[*Value][]*Block)
	t.latticeCells = make(map[*Value]lattice)
	t.visitedBlock = f.Cache.allocBoolSlice(f.NumBlocks())
	defer f.Cache.freeBoolSlice(t.visitedBlock)

	// build it early since we rely heavily on the def-use chain later
	t.buildDefUses()

	// pick up either an edge or SSA value from worklist, process it
	for {