79/2009 : From Trusted Annotations to Verified Knowledge

RR Number

79/2009

Conference

9th International Workshop on Worst-Case Execution Time Analysis (WCET 2009)

Author(s)

Adrian Prantl, Jens Knoop, Albrecht Kadlec, Markus Schordan

Abstract

WCET analyzers commonly rely on user-provided annotations such as loop bounds, recursion depths, region- and program constants. This reliance on user-provided annotations has an important drawback. It introduces a Trusted Annotation Basis into WCET analysis without any guarantee that the user-provided annotations are safe, let alone sharp. Hence, safety and accuracy of a WCET analysis cannot be formally established. In this paper we propose a uniform approach, which reduces the trusted annotation base to a minimum, while simultaneously yielding sharper (tighter) time bounds. Fundamental to our approach is to apply model checking in concert with other more inexpensive program analysis techniques, and the coordinated application of two algorithms for Binary Tightening and Binary Widening, which control the application of the model checker and hence the computational costs of the approach. Though in this paper we focus on the control of model checking by Binary Tightening and Widening, this is embedded into a more general approach in which we apply an array of analysis methods of increasing power and computational complexity for proving or disproving relevant time bounds of a program. First practical experiences using the sample programs of the Mälardalen benchmark suite demonstrate the usefulness of the overall approach. In fact, for most of these benchmarks we were able to empty the trusted annotation base completely, and to tighten the computed WCET considerably.

Bibtex

@InProceedings{Prantl:WCET2009_trust,
  author =       {Adrian Prantl and Jens Knoop and Raimund Kirner and 
                  Albrecht Kadlec and Markus Schordan},
  title =        {From Trusted Annotations to Verified Knowledge},
  booktitle =    {Proc. 9th International Workshop on Worst-Case Execution
                  Time Analysis},
  year =         {2009},
  address =      {Dublin, Ireland},
  month =        {June}
}

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Get submissionWCET2009-Sept7.pdf - Adobe PDF-format, (167.44 KB; posted at November 12 2009; )