stabilizer

Yes, just because it's from a team connected with the old Stabilizer tool, it doesn't mean it shares the insights and benefits of that kind of testing. At least, that's my understanding based on my limited knowledge of coz, and a little bit more knowledge of https://github.com/ccurtsinger/stabilizer

Yeah, I've watched that video. That's the source of my "I've also been pointed to https://github.com/ccurtsinger/stabilizer but it sounds tied to LLVM 3.1 and hasn't had any substantial updates since 2013."

I am the commit author. I wrote that commit on my laptop. I was unable to reproduce this on my desktop. Re "why does this happen?", it certainly looks like an alignment thing. A more interesting question for me is "what should I do about it?" If future non-trivial changes affect the micro-benchmark numbers, how do I ensure that it's signal and not noise? Do I sprinkle some alignment directives throughout my code and hope for the best? Once the immediate symptoms are gone, how do I know that I've added enough? Somebody suggested (off-list): "use compiler flags like the combo `-ffunction-sections -falign-functions=N` for values like 16, 32, 64 to help diagnose these issues quickly. You can also look at perf counters to find the problems, but each problem has a different counter so that can be hard. Once you know you have a problem, you can