A PDG-based Tool and its Use in Analyzing Program Control Dependences

This paper explores the potential of a program representation called the program dependence graph (PDG) for representing and exposing programs’ hierarchical control dependence structure. It presents several extensions to current PDG designs, including a node labeling scheme that simplifies and generalizes PDG traversal. A post-pass PDG-based tool called PEDIGREE has been implemented. It is used to generate and analyze the PDGs for several benchmarks, including the SPEC92 suite. In particular, initial results characterize the control dependence structure of these programs to provide insight into the scheduling benefits of employing speculative execution, and exploiting control equivalence information. Some of the benefits of using the PDG instead of the CFG are demonstrated. Our ultimate aim is to use this tool for exploiting multi-grained parallelism.