If you want an actually usably fast Free Software reversible debugger, I recommend giving rr a go (http://rr-project.org/ http://rr-project.org/). It works by r

If you want an actually usably fast Free Software reversible debugger, I recommend giving rr a go (http://rr-project.org/ http://rr-project.org/). It works by record-and-replay, and you can do step-backwards in the replay part. It's not perfect yet, but you can use it for serious work on complex multithreaded programs; I've used it for debugging QEMU bugs. I'm optimistic that this will become part of the standard open source C/C++ development toolkit in the same way that valgrind did.