Control-Flow Analysis and Type Systems

We establish a series of equivalences between type systems and control-flow analyses. Specifically, we take four type systems from the literature (involving simple types, subtypes and recursion) and conservatively enrich them to reason about control-flow information. Similarly, we take four standard control-flow systems and conservatively enrich them to reason about type consistency. Our main result is that for each type system, there is a control-flow system with equivalent reasoning power. In essence, type systems and control-flow analysis can be viewed as complementary approaches for addressing questions of type consistency and control-flow. This work was sponsored by the Advanced Research Projects Agency, CSTO, under the title “The Fox Project: Advanced Development of Systems Software”, ARPA Order No. 8313, issued by ESD/AVS under Contract No. F1962891-C-0168. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of ARPA or the U.S. Government.