> We have real hardware differences for a lot of simple things that make them hard or impossible to give defined behavior for. Hard or impossible to give _perf

> We have real hardware differences for a lot of simple things that make them hard or impossible to give defined behavior for. Hard or impossible to give _performant_ defined behavior for. > As an example, shifting left by more bits than the size of the value gives different results on several different platforms. You could, for instance, always mod the shift by the word size, but possibly at a significant cost.