Tag Archives: value-builtins

Probably safe donut
Pascal Cuoq on 17 September 2011

Introduction In the first post in the obfuscated animated donut series my colleague Anne pointed out that: The alarm about : assert \valid(". -~:;=!*#$@"+tmp_7); seems strange because the analysis tells us that tmp_7 ∈ [0..40] at this point... How can this be valid ? It is only safe to use...

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Safe donut
Pascal Cuoq on 16 September 2011

This post documents the steps I followed in order to finish verifying function compute(), picking up from there. Previously on this blog In last episode we had found that some sub-cubes in the search space appeared to lead to dangerous value sets for variable N. These sets were: N ∈...

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Linux and floating-point: nearly there
Pascal Cuoq on 14 September 2011

In the process of implementing the value analysis built-ins Frama_C_precise_sin() and Frama_C_precise_cos() from last post I stumbled on some interesting floating-point results. The sensationalistic title blames Linux but I didn't fully investigate the problem yet and it could be somewhere else. If you have the Frama-C sources lying around you...

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Better is the enemy of good... sometimes
Pascal Cuoq on 12 September 2011

This post is about widening. This technique was shown in the second part of a previous post about memcpy() where it was laboriously used to analyze imprecisely function memcpy() as it is usually written. The value analysis in Frama-C has the ability to summarize loops in less time than they...

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Fixing robots, part 1
Pascal Cuoq on 6 June 2011

This blog post is a revised version of part of my submission to the ICPC 2011 Industry Challenge. Please go ahead and read the challenge description. I could only paraphrase it without adding anything to it and so I won't. The study was made with the April development version of...

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