[libre-riscv-dev] multi issue

[Luke Kenneth Casson Leighton]

i've made the ALUs "Concurrent", passing in an operation (similar to
funct3) to a *batch* of ALUs, and got the engine to pause only if the
*entire batch* of ALUs is busy.  this works well and puts things on
track to being able to do multi-issue.

now that the ALUs are "banded together" in groups that handle
identical operations, i may add in an instruction FIFO first, or i may
try adding in LD/ST (not AMOs yet).

this is just... fascinating... :)

l.