Sure. In fact, once this bug was fixed I ran the same program through some tests with valgrind and found two more problems that were occurring less frequently.

Sure. In fact, once this bug was fixed I ran the same program through some tests with valgrind and found two more problems that were occurring less frequently. The difference is that with rr I can record and diagnose a specific crash. With valgrind I would have found three problems, fixed them, and the intermittent crashes would have gone away. On the one hand that’s good enough, but on the other hand I wouldn’t have found out that the weird crashes that couldn’t happen were because we were overwriting a vtable.