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When quoting this document, please refer to the following
DOI: 10.4230/OASIcs.WCET.2008.1660
URN: urn:nbn:de:0030-drops-16608
URL: http://drops.dagstuhl.de/opus/volltexte/2008/1660/
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Holsti, Niklas

Computing time as a program variable: a way around infeasible paths

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Abstract

Conditional branches connect the values of program variables with the execution paths and thus with the execution times, including the worst-case execution time (WCET). Flow analysis aims to discover this connection and represent it as loop bounds and other path constraints. Usually, a specific analysis of the dependencies between branch conditions and assign­ments to variables creates some representation of the feasible paths, for example as IPET execution-count constraints, from which a WCET bound is calculated. This paper explores another approach that uses a more direct connection between variable values and execution time. The execution time is modeled as a program variable. An analysis of the dependencies between variables, including the execution-time variable, gives a WCET bound that excludes many infeasible paths. Examples show that the approach often works, in principle. It remains to be seen if it is scalable to real programs.

BibTeX - Entry

@InProceedings{holsti:OASIcs:2008:1660,
  author =	{Niklas Holsti},
  title =	{{Computing time as a program variable: a way around infeasible paths}},
  booktitle =	{8th International Workshop on Worst-Case Execution Time Analysis (WCET'08)},
  series =	{OpenAccess Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-10-1},
  ISSN =	{2190-6807},
  year =	{2008},
  volume =	{8},
  editor =	{Raimund Kirner},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{http://drops.dagstuhl.de/opus/volltexte/2008/1660},
  URN =		{urn:nbn:de:0030-drops-16608},
  doi =		{http://dx.doi.org/10.4230/OASIcs.WCET.2008.1660},
  note =	{also published in print by Austrian Computer Society (OCG) with ISBN 978-3-85403-237-3},
  annote =	{Keywords: WCET, flow analysis, infeasible paths, dependency analysis}
}

Keywords: WCET, flow analysis, infeasible paths, dependency analysis
Seminar: 8th International Workshop on Worst-Case Execution Time WCET Analysis (WCET'08)
Issue Date: 2008
Date of publication: 13.11.2008


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