Extending OpenMP to facilitate loop optimization

Ian Bertolacci, Michelle Mills Strout, Bronis R. de Supinski, Thomas R.W. Scogland, Eddie C. Davis, Catherine Olschanowsky

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


OpenMP provides several mechanisms to specify parallel source-code transformations. Unfortunately, many compilers perform these transformations early in the translation process, often before performing traditional sequential optimizations, which can limit the effectiveness of those optimizations. Further, OpenMP semantics preclude performing those transformations in some cases prior to the parallel transformations, which can limit overall application performance. In this paper, we propose extensions to OpenMP that require the application of traditional sequential loop optimizations. These extensions can be specified to apply before, as well as after, other OpenMP loop transformations. We discuss limitations implied by existing OpenMP constructs as well as some previously proposed (parallel) extensions to OpenMP that could benefit from constructs that explicitly apply sequential loop optimizations. We present results that explore how these capabilities can lead to as much as a 20% improvement in parallel loop performance by applying common sequential loop optimizations.

Original languageEnglish (US)
Title of host publicationEvolving OpenMP for Evolving Architectures - 14th International Workshop on OpenMP, IWOMP 2018, Proceedings
EditorsPedro Valero-Lara, Sergi Mateo Bellido, Xavier Martorell, Jesus Labarta, Bronis R. de Supinski
Number of pages13
ISBN (Print)9783319985206
StatePublished - 2018
Event14th International Workshop on OpenMP, IWOMP 2018 - Barcelona, Spain
Duration: Sep 26 2018Sep 28 2018

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11128 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference14th International Workshop on OpenMP, IWOMP 2018


  • Heterogeneous adaptive worksharing
  • Loop chain abstraction
  • Loop optimization
  • Memory transfer pipelining

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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