Abstract
In [1], Dieter an Mey proposes the addition of an AUTO attribute to the OpenMP DEFAULT clause. A DEFAULT(AUTO) clause would cause the compiler to automatically determine the scoping of variables that are not explicitly classified as shared, private or reduction. While this new feature would be useful and powerful, its implementation would rely on automatic parallelization technology, which has been shown to have significant limitations. In this paper, we implement support for the DEFAULT(AUTO) clause in the Polaris parallelizing compiler. Our modified version of the compiler will translate regions with DEFAULT(AUTO) clauses into regions that have explicit scopings for all variables. An evaluation of our implementation on a subset of the SPEC OpenMP Benchmark Suite shows that with current automatic parallelization technologies, a number of important regions cannot be statically scoped, resulting in a significant loss of speedup. We also compare our compiler’s performance to that of an Early Access version of the Sun Studio 9 Fortran 95 compiler [2].
This work is supported in part by the Canadian National Science and Engineering Research Council, the Canada Foundation for Innovation, the Ontario Innovation Trust, the Connaught Foundation and the University of Toronto.
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Voss, M., Chiu, E., Chow, P.M.Y., Wong, C., Yuen, K. (2005). An Evaluation of Auto-Scoping in OpenMP. In: Chapman, B.M. (eds) Shared Memory Parallel Programming with Open MP. WOMPAT 2004. Lecture Notes in Computer Science, vol 3349. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-31832-3_9
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DOI: https://doi.org/10.1007/978-3-540-31832-3_9
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