[Libre-soc-dev] WIP demo of deficiency of 6600-derived architecture compared to register renaming

[Luke Kenneth Casson Leighton]

i have an idea, part of the register cache which has to do renaming
anyway, sigh.  have (yet another) register tracker which spots when
regs are written to and increments a small counter (per reg).  the
counter is appended r5.%d to give the name going in to the register
cache.

the question is, how to detect "rollover" where the counter wraps.
part of the register "cache flush"? writeback time gives us the
counter that is still active?

this would solve the renaming you identified jacob but not the
opportunities to drop overwritten regs (maybe?) however it has the
advantage of being a lot less gates.  doubling or tripling FU-REGs
size is too much.

l.