>>> If a RISC CPU has a µop cache, the space-efficiency of the µop cache
>>> can be better than the space-efficiency of RISC instructions
>>
>> If it is possible to make the encoding in the µop cache more space efficient than the encoding
>> of RISC instructions, why didn’t the RISC processor use the µops as its instruction set?
>
> Because it is mathematically impossible to compress 1 TiB of random binary data into 32 KiB of space and be able
> to load/store 64-byte randomly selected chunks from/to the 32 KiB space with a throughput of 1 chunk per CPU cycle.

I don’t understanding you here. How is it ever possible to losslessly compress 1 TiB of random binary data into 32 KiB of space under any conditions? A uop cache has to support random accesses to support branches so any compression method that prevents random accesses can not be used. I thought you were saying that the encoding of instructions in a uop cache is more efficient than the encoding of RISC instructions so a uop cache is useful for a RISC processor. I don’t understand why a uop cache is useful in a RISC processor.