Efficient search for inputs causing high floating-point errors

  • Authors:
  • Wei-Fan Chiang;Ganesh Gopalakrishnan;Zvonimir Rakamaric;Alexey Solovyev

  • Affiliations:
  • University of Utah, Salt Lake City, UT, USA;University of Utah, Salt Lake City, UT, USA;University of Utah, Salt Lake City, UT, USA;University of Utah, Salt Lake City, UT, USA

  • Venue:
  • Proceedings of the 19th ACM SIGPLAN symposium on Principles and practice of parallel programming
  • Year:
  • 2014

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Abstract

Tools for floating-point error estimation are fundamental to program understanding and optimization. In this paper, we focus on tools for determining the input settings to a floating point routine that maximizes its result error. Such tools can help support activities such as precision allocation, performance optimization, and auto-tuning. We benchmark current abstraction-based precision analysis methods, and show that they often do not work at scale, or generate highly pessimistic error estimates, often caused by non-linear operators or complex input constraints that define the set of legal inputs. We show that while concrete-testing-based error estimation methods based on maintaining shadow values at higher precision can search out higher error-inducing inputs, suit able heuristic search guidance is key to finding higher errors. We develop a heuristic search algorithm called Binary Guided Random Testing (BGRT). In 45 of the 48 total benchmarks, including many real-world routines, BGRT returns higher guaranteed errors. We also evaluate BGRT against two other heuristic search methods called ILS and PSO, obtaining better results.