Automatic Relative Debugging of OpenMP Programs

In this work we show how automatic relative debugging can be used to find differences in computation between a correct serial program and an OpenMP parallel version of that program that does not yield correct results. Back- tracking and re-execution are used to determine the first OpenMP parallel region that produces a difference in com- putation that may lead to an incorrect value the user has indicated. Our approach also lends itself to finding differ- ences between parallel computations, where executing with threads produces expected results but an thread exe- cution does not ( , ). OpenMP programs created using a parallelization tool are addressed by utiliz- ing static analysis and directive information from the tool. Hand-parallelized programs, where OpenMP directives are inserted by the user, are addressed by performing data de- pendence and directive analysis.