//	5,       For any successor s of b, try to update relationship b->s, if a
//	         contradiction is found then redirect p to another successor of b.
func fuseBranchRedirect(f *Func) bool {
	ft := newFactsTable(f)
	ft.checkpoint()

	changed := false
	for i := len(f.Blocks) - 1; i >= 0; i-- {
		b := f.Blocks[i]
		if b.Kind != BlockIf {
			continue
		}
		// b is either empty or only contains the control value.

	zero *Value
}

// checkpointFact is an invalid value used for checkpointing
// and restoring factsTable.
var checkpointFact = fact{}
var checkpointBound = limitFact{}

func newFactsTable(f *Func) *factsTable {
	ft := &factsTable{}
	ft.orderS = f.newPoset()
	ft.orderU = f.newPoset()
	ft.orderS.SetUnsigned(false)
	ft.orderU.SetUnsigned(true)
	ft.facts = make(map[pair]relation)