func layout(f *Func) {
	f.Blocks = layoutOrder(f)
}

// Register allocation may use a different order which has constraints
// imposed by the linear-scan algorithm.
func layoutRegallocOrder(f *Func) []*Block {
	// remnant of an experiment; perhaps there will be another.
	return layoutOrder(f)
}

func layoutOrder(f *Func) []*Block {
	order := make([]*Block, 0, f.NumBlocks())

	// Decouple the register allocation order from the generated block order.
	// This also creates an opportunity for experiments to find a better order.
	s.visitOrder = layoutRegallocOrder(f)

	// Compute block order. This array allows us to distinguish forward edges
	// from backward edges and compute how far they go.
	s.blockOrder = make([]int32, f.NumBlocks())
	for i, b := range s.visitOrder {