Comment by charleslmunger

This can be really tricky to do. I reached the limit of my brain's working capacity designing a priority inheritance system, and sketched the state machine out in a dot file, visualized with graphviz - this worked really well for reasoning through the correctness of the algorithm and explaining it to others. I tried to structure the implementation code to match it and I was able to get pretty close; but the actual states were a bunch of bit-packing and duplicated control flow to get optimal assembly output for the hottest paths. Each one of those changes was easy to reason about as an isolated correct transformation of the original structure in code, but would have been a mess visually.