Method IsValid

cfa/pre_loop.go:108–131

IsValid reports whether the cond, body and exit node candidates of prim form a valid pre-test loop in g. Control flow graph: cond ↓ ↖↘ ↓ body ↓ exit

(g graph.Directed, dom cfg.DominatorTree)

//    ↓
//    exit
func (prim PreLoop) IsValid(g graph.Directed, dom cfg.DominatorTree) bool {
	// Dominator sanity check.
	cond, body, exit := prim.Cond, prim.Body, prim.Exit
	if !dom.Dominates(cond, body) || !dom.Dominates(cond, exit) {
		return false
	}

	// Verify that cond has two successors (body and exit).
	condSuccs := g.From(cond)
	if len(condSuccs) != 2 || !g.HasEdgeFromTo(cond, body) || !g.HasEdgeFromTo(cond, exit) {
		return false
	}

	// Verify that body has one predecessor (cond) and one successor (cond).
	bodyPreds := g.To(body)
	bodySuccs := g.From(body)
	if len(bodyPreds) != 1 || len(bodySuccs) != 1 || !g.HasEdgeFromTo(body, cond) {
		return false
	}

	// Verify that exit has one predecessor (cond).
	exitPreds := g.To(exit)
	return len(exitPreds) == 1
}