I'm curious how people assumed these work? Allowing step debugging already precludes a ton of possible optimizations that a compiler might otherwise be able to do. No?
If you compile for an optimized level you probably will see your debugger jump around and skip random things. It just depends on what the optimizer did to the code. Have made that mistake enough times to watch it in action.
Right, I'm assuming the places where you would notice that conditional debugs are slow are also the places where you will have trouble with step debugging, in general?
Hmm would not think so. As the IDE does not really care much about that. The backend just says 'you are near this spot in the code'. In the IDE it looks like things just 'dont exist' or the current line pointer will jump around when you compile release mode. Whereas in 'debug' (or O0) the compiler just emits the code in the most simplistic way possible so things tend to stay in order. While 'release' (or O1 to O3) can (and will) move things around to remove processor pipeline stalls, optimizations, and other intrinsics.
Conditional is going to have some overhead because it has to re-evaluate the condition on every step of the program counter if you are near the offending line or not. While line stepping is more closer to a lookup table of where in the parsed strings are you compared to the current program counter. Which is a much simpler lookup and the previous step was nearby (so probably less than logn but not quite 1). While a conditional would have at least N search (all of your break points plus the calculation of the variables for the condition). Some hardware also assists with breakpoints by popping an exception when you hit a particular program counter making it much faster in some cases. Whereas with a conditional you have to ignore the hardware and do it the 'hard way' on every virtual step of the PC.
I think you are talking past me? My point is the easy code is not where you would want to put breakpoints. It isn't a matter of the IDE, it is a matter of the likelihood that you want a breakpoint in a tight loop. And if you do, you will be working against optimizations and adding far more code to execute than a single condition.
Is like someone adding what feels like a single field to a query, not accounting for the effort that goes into a join.
Edit: I should add that "difficulty with step debugging" isn't just "won't work." I picture "having to press resume a few hundred times to get exactly where I want to be" as difficulty, there.