[bippingchip]

Very nice explanation! It gets very complex very quickly... And then there's of course also the fact you never know if your last bytes in the Ifetch you get from the cache is a full instruction or not. You'll need to keep that around until the next line arrives which will have the rest of that instruction.

And then add to that the complexity of speculative and out of order execution: you will want to very early decide, i.e. (pre)decode, where branch instructions are, in order to make sure your branch prediction unit has the right inputs in time, to decide where to fetch the next instructions from.

And after all that, on a branch mispredict earlier on (or pipeline flush for another reason), you might need to throw almost all of that expensively decoded instructions away and start fetching from elsewhere...

CPUs are fun :)