[jacquesm]

You can't tell whether a register contains a memory address or not after it has just been fetched right up until the moment that it is used. If the instruction stream contains instructions that reference that register that are within the look-ahead window of the instruction pipeline then maybe this might work, but if there is any conditional code in there or something else that causes the value to be used in a way that is not 'as a pointer' and to access the memory (and not for for instance pointer arithmetic prior to utilization) then such a pre-fetch would likely cause more harm than good by blowing good data out of the cache and replacing it with useless data (at a significant penalty).

There has been some research on this subject with respect to compiler optimizations but as far as I know this is not at all done at the hardware level.