Tuesday, July 3, 2018

Debugging With C-Reduce

Mike Ash (Hacker News):

Debugging a complex problem is tough, and it can be especially difficult when it’s not obvious which chunk of code is responsible. It’s common to attempt to produce a reduced test case in order to narrow it down. It’s tedious to do this manually, but it’s also the sort of thing computers are really good at. C-Reduce is a program which automatically takes programs and pares them down to produce a reduced test case.


When you use C-Reduce, you provide not only a program to reduce but also a small script which tests whether a reduced program is “interesting.” Exactly what “interesting” means is up to you. If you’re trying to isolate a bug, then “interesting” would mean that the bug still occurs in the program. You can define it to mean whatever you want, as long as you can script it. Whatever test you provide, C-Reduce will try to provide a reduced version of the program that still passes the test.


Blind reduction of a test case is not a very sophisticated debugging technique, but the ability to automate it can make it extremely useful. C-Reduce can be a fantastic addition to your debugging toolbox.

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