// beginning of prove where we look for all len/cap ops.
	if v.Op == OpSliceLen && r&lt == 0 && ft.caps[v.Args[0].ID] != nil {
		// len(s) > w implies cap(s) > w
		// len(s) >= w implies cap(s) >= w
		// len(s) == w implies cap(s) >= w
		ft.update(parent, ft.caps[v.Args[0].ID], w, d, r|gt)
	}
	if w.Op == OpSliceLen && r&gt == 0 && ft.caps[w.Args[0].ID] != nil {
		// same, length on the RHS.