An empirical study of predicate dependence levels and trends

Many source code analyses are closely related to and strongly influenced by interdependence among program components. This paper reports results from an empirical study of the interdependences involving program predicates and the formal parameters and global variables which potentially affect them. The findings show that it is possible to eliminate from consideration approximately 30% of the formal parameters, 50% of the ´touched´ global variables, and 97% of the ´visible´ global variables. Another important and encouraging finding is a strong inverse correlation between the number of formal parameters and dependence level. The fact that no such correlation was found for global variables provides evidence to support the conjecture that global variables are harmful.