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Reproducibility in Computer Systems Research
These results about reproducibility in CS have been the subject of lively discussion at Facebook and G+ lately. The question is, for 613 papers, can the associated software be located, compiled, and run? In contrast with something I often worry about — producing good software — the bar here is low, since even a system…
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Let’s Work on an LLVM Superoptimizer
A compiler optimization has two basic parts. First, it needs to recognize an optimizable situation in the IR (intermediate representation), such as adjacent increments of the same variable. For the optimization to be maximally effective, the situation recognizer should cast as wide a net as possible. For example, we might broaden the applicability of an…
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Writing Solid Code Weeks 7 and 8
The students continued with their compressor/decompressor development. Coverity continued to find plenty of issues for the students to fix. I’m about to start doing a bit of differential testing of their code, using voting to determine who is correct and who is wrong. I lectured on paranoid programming and on building a fuzzer, for sort…
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Paranoid Programming
A lot of software defects stem from developers who lack a proper sense of paranoia. While paranoia can of course be taken to idiotic extremes, a healthy respect for Murphy’s Law is useful in programming. This post is a list of useful paranoid techniques that I hope to use as the basis for a lecture…
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Use of Assertions
Assertions are great because they: support better testing, make debugging easier by reducing the distance between the execution of a bug and the manifestation of its effects, serve as executable comments about preconditions and postconditions, can act as a gateway drug to formal methods. Assertions are less than great because they: slow down our code,…