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Documents authored by Cullmann, Christoph


Document
Embedded Program Annotations for WCET Analysis

Authors: Bernhard Schommer, Christoph Cullmann, Gernot Gebhard, Xavier Leroy, Michael Schmidt, and Simon Wegener

Published in: OASIcs, Volume 63, 18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018)


Abstract
We present __builtin_ais_annot(), a user-friendly, versatile way to transfer annotations (also known as flow facts) written on the source code level to the machine code level. To do so, we couple two tools often used during the development of safety-critical hard real-time systems, the formally verified C compiler CompCert and the static WCET analyzer aiT. CompCert stores the AIS annotations given via __builtin_ais_annot() in a special section of the ELF binary, which can later be extracted automatically by aiT.

Cite as

Bernhard Schommer, Christoph Cullmann, Gernot Gebhard, Xavier Leroy, Michael Schmidt, and Simon Wegener. Embedded Program Annotations for WCET Analysis. In 18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018). Open Access Series in Informatics (OASIcs), Volume 63, pp. 8:1-8:13, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@InProceedings{schommer_et_al:OASIcs.WCET.2018.8,
  author =	{Schommer, Bernhard and Cullmann, Christoph and Gebhard, Gernot and Leroy, Xavier and Schmidt, Michael and Wegener, Simon},
  title =	{{Embedded Program Annotations for WCET Analysis}},
  booktitle =	{18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018)},
  pages =	{8:1--8:13},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-073-6},
  ISSN =	{2190-6807},
  year =	{2018},
  volume =	{63},
  editor =	{Brandner, Florian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2018.8},
  URN =		{urn:nbn:de:0030-drops-97543},
  doi =		{10.4230/OASIcs.WCET.2018.8},
  annote =	{Keywords: Worst-Case Execution Time (WCET) Analysis, Annotation Support, CompCert, Tool Coupling, aiT}
}
Document
Fine-Grain Iterative Compilation for WCET Estimation

Authors: Isabelle Puaut, Mickaël Dardaillon, Christoph Cullmann, Gernot Gebhard, and Steven Derrien

Published in: OASIcs, Volume 63, 18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018)


Abstract
Compiler optimizations, although reducing the execution times of programs, raise issues in static WCET estimation techniques and tools. Flow facts, such as loop bounds, may not be automatically found by static WCET analysis tools after aggressive code optimizations. In this paper, we explore the use of iterative compilation (WCET-directed program optimization to explore the optimization space), with the objective to (i) allow flow facts to be automatically found and (ii) select optimizations that result in the lowest WCET estimates. We also explore to which extent code outlining helps, by allowing the selection of different optimization options for different code snippets of the application.

Cite as

Isabelle Puaut, Mickaël Dardaillon, Christoph Cullmann, Gernot Gebhard, and Steven Derrien. Fine-Grain Iterative Compilation for WCET Estimation. In 18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018). Open Access Series in Informatics (OASIcs), Volume 63, pp. 9:1-9:12, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@InProceedings{puaut_et_al:OASIcs.WCET.2018.9,
  author =	{Puaut, Isabelle and Dardaillon, Micka\"{e}l and Cullmann, Christoph and Gebhard, Gernot and Derrien, Steven},
  title =	{{Fine-Grain Iterative Compilation for WCET Estimation}},
  booktitle =	{18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018)},
  pages =	{9:1--9:12},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-073-6},
  ISSN =	{2190-6807},
  year =	{2018},
  volume =	{63},
  editor =	{Brandner, Florian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2018.9},
  URN =		{urn:nbn:de:0030-drops-97556},
  doi =		{10.4230/OASIcs.WCET.2018.9},
  annote =	{Keywords: Worst-Case Execution Time Estimation, Compiler optimizations, Iterative Compilation, Flow fact extraction, Outlining}
}
Document
Software Structure and WCET Predictability

Authors: Gernot Gebhard, Christoph Cullmann, and Reinhold Heckmann

Published in: OASIcs, Volume 18, Bringing Theory to Practice: Predictability and Performance in Embedded Systems (2011)


Abstract
Being able to compute worst-case execution time bounds for tasks of an embedded software system with hard real-time constraints is crucial to ensure the correct (timing) behavior of the overall system. Any means to increase the (static) time predictability of the embedded software are of high interest -- especially due to the ever-growing complexity of such software systems. In this paper we study existing coding proposals and guidelines, such as MISRA-C, and investigate whether they simplify static timing analysis. Furthermore, we investigate how additional knowledge, such as design-level information, can further aid in this process.

Cite as

Gernot Gebhard, Christoph Cullmann, and Reinhold Heckmann. Software Structure and WCET Predictability. In Bringing Theory to Practice: Predictability and Performance in Embedded Systems. Open Access Series in Informatics (OASIcs), Volume 18, pp. 1-10, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2011)


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@InProceedings{gebhard_et_al:OASIcs.PPES.2011.1,
  author =	{Gebhard, Gernot and Cullmann, Christoph and Heckmann, Reinhold},
  title =	{{Software Structure and WCET Predictability}},
  booktitle =	{Bringing Theory to Practice: Predictability and Performance in Embedded Systems},
  pages =	{1--10},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-28-6},
  ISSN =	{2190-6807},
  year =	{2011},
  volume =	{18},
  editor =	{Lucas, Philipp and Wilhelm, Reinhard},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.PPES.2011.1},
  URN =		{urn:nbn:de:0030-drops-30836},
  doi =		{10.4230/OASIcs.PPES.2011.1},
  annote =	{Keywords: WCET Predictability, Embedded Software Structure, Coding Guidelines}
}
Document
Integrating Abstract Caches with Symbolic Pipeline Analysis

Authors: Stephan Wilhelm and Christoph Cullmann

Published in: OASIcs, Volume 15, 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)


Abstract
Static worst-case execution time analysis of real-time tasks is based on abstract models that capture the timing behavior of the processor on which the tasks run. For complex processors, task-level execution time bounds are obtained by a state space exploration which involves the abstract model and the program. Partial state space exploration is not sound. Symbolic methods using binary decision diagrams (BDDs) allow for a full state space exploration of the pipeline, thereby maintaining soundness. Caches are too large to admit an efficient BDD representation. On the other hand, invariants of the cache state can be computed efficiently using abstract interpretation. How to integrate abstract caches with symbolic-state pipeline analysis is an open question. We propose a semi-symbolic domain to solve this problem. Statistical data from industrial-level software and WCET tools indicate that this new domain will enable an efficient analysis.

Cite as

Stephan Wilhelm and Christoph Cullmann. Integrating Abstract Caches with Symbolic Pipeline Analysis. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 36-43, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2010)


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@InProceedings{wilhelm_et_al:OASIcs.WCET.2010.36,
  author =	{Wilhelm, Stephan and Cullmann, Christoph},
  title =	{{Integrating Abstract Caches with Symbolic Pipeline Analysis}},
  booktitle =	{10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
  pages =	{36--43},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-21-7},
  ISSN =	{2190-6807},
  year =	{2010},
  volume =	{15},
  editor =	{Lisper, Bj\"{o}rn},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2010.36},
  URN =		{urn:nbn:de:0030-drops-28235},
  doi =		{10.4230/OASIcs.WCET.2010.36},
  annote =	{Keywords: WCET analysis, cache analysis, pipeline analysis}
}
Document
Data-Flow Based Detection of Loop Bounds

Authors: Christoph Cullmann and Florian Martin

Published in: OASIcs, Volume 6, 7th International Workshop on Worst-Case Execution Time Analysis (WCET'07) (2007)


Abstract
To calculate the WCET of a program, safe upper bounds on the number of loop iterations for all loops in the program are needed. As the manual annotation of all loops with such bounds is difficult and time consuming, the WCET analyzer aiT originally developed by Saarland University and AbsInt GmbH uses static analysis to determine the needed bounds as far as possible. This paper describes a novel data-flow based analysis for aiT to calculate the needed loop bounds on the assembler level. The new method is compared with a pattern based loop analysis already in use by this tool.

Cite as

Christoph Cullmann and Florian Martin. Data-Flow Based Detection of Loop Bounds. In 7th International Workshop on Worst-Case Execution Time Analysis (WCET'07). Open Access Series in Informatics (OASIcs), Volume 6, pp. 1-6, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2007)


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@InProceedings{cullmann_et_al:OASIcs.WCET.2007.1193,
  author =	{Cullmann, Christoph and Martin, Florian},
  title =	{{Data-Flow Based Detection of Loop Bounds}},
  booktitle =	{7th International Workshop on Worst-Case Execution Time Analysis (WCET'07)},
  pages =	{1--6},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-05-7},
  ISSN =	{2190-6807},
  year =	{2007},
  volume =	{6},
  editor =	{Rochange, Christine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2007.1193},
  URN =		{urn:nbn:de:0030-drops-11934},
  doi =		{10.4230/OASIcs.WCET.2007.1193},
  annote =	{Keywords: WCET analysis, loop bound detection, flow analysis}
}
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