Re: Pedant Alert
But adding instructions gives you very little in the near-term. There is too much that has to be done before any benefit is improved:
-First new compilers need to be built
-Then you'd have to re-compile new OS kernels and maintain multiple version (One for each version of the instruction set)
-Then there is the effort of maintaining application binaries for each version of the instruction set or include quite a bit of bloat to determine what chip is in the system and branch if its supported or not (Of course a JIT-compiled language would alleviate the needs of this, but still...)
The only reason Apple was able to do such things was that they has unilateral control over every layer of the system from the silicon to APIs. This allows them to make changes in parallel so that the Instruction set and OS take full advantage of each other (Proc is optimized for new OS features, OS fully utilizes every improvement in the silicon). Add this to the fact that they locked versions of the OS to machine models and you can make all the changes to the instruction set you could ever want.
However this would never work on a free system where you have choice of OS and hardware can be heavily customized for your purposes.