Clarifying Unspecified Values, Kayvan Memarian and Peter Sewell. ISO SC22 WG14 N2089, http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2089.htm, September 2016. [ bib | project page | html ]
 
Clarifying Pointer Provenance, Kayvan Memarian and Peter Sewell. ISO SC22 WG14 N2090, http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2090.htm, September 2016. [ bib | project page | html ]
 
Clarifying Trap Representations, Kayvan Memarian and Peter Sewell. ISO SC22 WG14 N2091, http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2091.htm, September 2016. [ bib | project page | html ]
 
Into the depths of C: elaborating the de facto standards. Kayvan Memarian, Justus Matthiesen, James Lingard, Kyndylan Nienhuis, David Chisnall, Robert N.M. Watson, and Peter Sewell. In PLDI 2016, PLDI 2016 Distinguished Paper award. [ bib | doi | project page | pdf | http ]
C remains central to our computing infrastructure. It is notionally defined by ISO standards, but in reality the properties of C assumed by systems code and those implemented by compilers have diverged, both from the ISO standards and from each other, and none of these are clearly understood.

We make two contributions to help improve this error-prone situation. First, we describe an in-depth analysis of the design space for the semantics of pointers and memory in C as it is used in practice. We articulate many specific questions, build a suite of semantic test cases, gather experimental data from multiple implementations, and survey what C experts believe about the de facto standards. We identify questions where there is a consensus (either following ISO or differing) and where there are conflicts. We apply all this to an experimental C implemented above capability hardware. Second, we describe a formal model, Cerberus, for large parts of C. Cerberus is parameterised on its memory model; it is linkable either with a candidate de facto memory object model, under construction, or with an operational C11 concurrency model; it is defined by elaboration to a much simpler Core language for accessibility, and it is executable as a test oracle on small examples.

This should provide a solid basis for discussion of what mainstream C is now: what programmers and analysis tools can assume and what compilers aim to implement. Ultimately we hope it will be a step towards clear, consistent, and accepted semantics for the various use-cases of C.

 
Clarifying the C memory object model, Kayvan Memarian and Peter Sewell. ISO SC22 WG14 N2012, http://www.cl.cam.ac.uk/~pes20/cerberus/notes64-wg14.html, March 2016. [ bib | project page | html ]
 
C memory object and value semantics: the space of de facto and ISO standards, David Chisnall, Justus Matthiesen, Kayvan Memarian, Kyndylan Nienhuis, Peter Sewell, and Robert N. M. Watson. ISO SC22 WG14 N2013, http://www.cl.cam.ac.uk/~pes20/cerberus/notes30.pdf, March 2016. [ bib | project page | pdf ]
 
What is C in practice? (Cerberus survey v2): Analysis of Responses, Kayvan Memarian and Peter Sewell. ISO SC22 WG14 N2014, http://www.cl.cam.ac.uk/~pes20/cerberus/notes50-survey-discussion.html, March 2016. [ bib | project page | html ]
 
What is C in practice? (Cerberus survey v2): Analysis of Responses -- with Comments, Kayvan Memarian and Peter Sewell. ISO SC22 WG14 N2015, http://www.cl.cam.ac.uk/~pes20/cerberus/analysis-2016-02-05-anon.txt, March 2016. [ bib | project page | txt ]