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Pure functions in C: A small keyword for automatic parallelization

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journal contribution
posted on 09.06.2020, 09:18 by T Süß, Lars NagelLars Nagel, MA Vef, A Brinkmann, D Feld, T Soddemann
© 2020, The Author(s). The need for parallel task execution has been steadily growing in recent years since manufacturers mainly improve processor performance by increasing the number of installed cores instead of scaling the processor’s frequency. To make use of this potential, an essential technique to increase the parallelism of a program is to parallelize loops. Several automatic loop nest parallelizers have been developed in the past such as PluTo. The main restriction of these tools is that the loops must be statically analyzable which, among other things, disallows function calls within the loops. In this article, we present a seemingly simple extension to the C programming language which marks functions without side-effects. These functions can then basically be ignored when the automatic parallelizer checks the parallelizability of loops. We integrated the approach into the GCC compiler toolchain and evaluated it by running several real-world applications. Our experiments show that the C extension helps to identify additional parallelization opportunities and, thus, to significantly increase the performance of applications.

Funding

German Ministry for Education and Research (BMBF) under project Grant 01|H13004A (FAST)

German Research Foundation (DFG) through the German Priority Programme 1648 “Software for Exascale Computing” (SPPEXA)

ADA-FS project

Projekt DEAL

History

School

  • Science

Department

  • Computer Science

Published in

International Journal of Parallel Programming

Volume

49

Pages

1–24

Publisher

Springer

Version

VoR (Version of Record)

Rights holder

© The authors

Publisher statement

This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

05/05/2020

Publication date

2020-05-30

Copyright date

2021

ISSN

0885-7458

eISSN

1573-7640

Language

en

Depositor

Dr Lars Nagel Deposit date: 9 June 2020