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Pre-sorted Prefetch

I asked my self how can possible be for a processor to execute every instruction in a single clock and, besides, what is the gain if it will have to fetch the code anyways. The answer is, of course, prefetch and pipelining. Then it occurred to me that I could "easily" implement a prefetch scheme in which code is unmistakable available to the CPU. This is the idea:

There are actually two processors, one into the other. The outer one is in charge of prefetching, nothing else. If my "Trans Matrix" idea holds, then this would be processor who dealed with the Matrix for making address translation and that stuff but this is not important now; the interesting part is how this processor will do prefetch and how is the prefetched storage area.

Well, the prefetch area is actually a stack. The inner CPU (the "real" one) will use its PC as a stack pointer. It simply pops code from the "stack" and executes it right away, no fetch needed. Moreover, the stack itself could be used as IR with no need for a transfer. I will forget about pipelines for now; with just having the code right in place all the time would be a tremendous improvement with respect to the old-fashioned approach I'm taking for the Heritage/1.

So the outer processor (or "preprocessor", as we may call it) needs to make sure that the code is being placed in the right order. So this gay is smart, it knows the instructions set or at least it knows branch instructions.

Knowing this, it will do jumps along its memory reading, following the program flow and making sure the "stack" content is not only prefetched but also "pre-sorted". You may be asking: What about conditional braches? You are right; prefetch prediction is too complicated so the "pre-processor" will simply stop prefetching as soon as it encounter a conditional branch.

Another question you may be asking is about data. Well, in reallity there are two stacks: one for code, the other for data. The computer is Havard inside, Von Neuman outside... something like that.

Well, that is the idea. I know it's not as easy I've said (I know by experience that finding things easy is not a good sign) but I found it cool and wanted to write it down.