Summary When trying to parallelize a sequential program, programmers routinely struggle during the first step: finding out which code sections can be made to run in parallel. While identifying such code sections, most of the current parallelism discovery techniques focus on specific language constructs. In contrast, we propose to concentrate on the computations performed by a program. In our approach, a program is treated as a collection of computations communicating with one another using a number of variables. Each computation is represented as a computational unit (CU). A CU contains the inputs and outputs of a computation, and the three phases of a computation are read, compute, and write. Based on the notion of CU, which ensures that the read phase executes before the write phase, we present a unified framework to identify both loop parallelism and task parallelism in sequential programs. We conducted a range of experiments on 23 applications from four different benchmark suites. Our approach accurately identified the parallelization opportunities in benchmark applications based on comparison with their parallel versions. We have also parallelized the opportunities identified by our approach that were not implemented in the parallel versions of the benchmarks and reported the speedup.

Parallel design patterns have been developed to help programmers efficiently design and implement parallel applications. However, identifying a suitable parallel pattern for a specific code region in a sequential application is a difficult task. Transforming an application according to support structures applicable to these parallel patterns is also very challenging. In this paper, we present a novel approach to automatically find parallel patterns in the algorithm structure design space of sequential applications. In our approach, we classify code blocks in a region according to the appropriate supportstructure of the detected pattern. This classification eases the transformation of a sequential application into its parallel version. Weevaluated our approach on 17 applications from four different benchmark suites. Our method identified suitable algorithm structure patterns in the sequential applications. We confirmed our results by comparing them with the existing parallel versions of these applications. We also implemented the patterns we detected in cases in which parallel implementations were not available and achieved speedups of up to 14x.

The triumphant spread of multicore processors over the past decade increases the pressure on software developers to exploit the growing amount of parallelism available in the hardware. However, writing parallel programs is generally challenging. For sequential programs, the formulation of design patterns marked a turning point in software development, boosting programmer productivity and leading to more reusable and maintainable code. While the literature is now also reporting a rising number of parallel design patterns, programmers confronted with the task of parallelizing an existing sequential program still struggle with the question of which parallel pattern to apply where in their code. In this article, we show how template matching, a technique traditionally used in the discovery of sequential design patterns, can also be used to support parallelization decisions. After looking for matches in a previously extracted dynamic dependence graph, we classify code blocks of the input program according to the structure of the parallel patterns we find. Based on this information, the programmer can easily implement the detected pattern and create a parallel version of his or her program. We tested our approach with six programs, in which we successfully detected pipeline and do-all patterns.