The instruction set architecture has no concept of it either, nor about instruction level parallelism, branch prediction or speculative execution. There is no way of getting this right other than knowing about how the processor is implemented under the hood and issue the right assembly based on that. Often experimentation is needed to get it right.

To fix this, the instruction set need to be changed, and this need to be kept in order to keep it compatible with earlier versions. Thus the instruction set remains as it is with the exception that new instruction may be added.