[olliej]

If you implemented any language following the spec in a step by step manner they would be dog slow, because any usable spec has to be very explicit in every step required for every operation.

All those conversions that you believe only happen if you implement the spec “step by step” always happen.

Actual implementations of languages then implement the explicitly described semantics, in whatever way they feel is most efficient.

[titzer]

Bah. Compiling Java to bytecode consists of a lot of static resolution steps and then a fairly straightforward, simple translation. Single-stepping the bytecodes will absolutely produce the same results as the optimized JIT code and there are few expressions that generate more than 1 to a handful of bytecodes.