Abstract

Flowback analysis is a powerful technique for debugging programs. It allows the programmer to examine dynamic dependences in a program's execution history without having to re-execute the program. The goal is to present to the programmer a graphical view of the dynamic program dependences. We are building a system, called PPD, that performs flowback analysis while keeping the execution time overhead low. We also extend the semantics of flowback analysis to parallel programs. This paper describes details of the graphs and algorithms needed to implement efficient flowback analysis for parallel programs. Execution time overhead is kept low by recording only a small amount of trace during a program's execution. We use semantic analysis and a technique called incremental tracing to keep the time and space overhead low. As part of the semantic analysis, PPD uses a static program dependence graph structure that reduces the amount of work done at compile time and takes advantage of the dynamic...

Citations