Accelerator.SM121.Lowering

--------------------------------------------------------------------------- The static scoreboard check A lowered program is walked again from its final words alone -- the issue cycle of each instruction from the stalls before it, the scoreboards from its control fields -- and every hazard counted: * a register read (or written) before a fixed-latency writer's result is ready for it, or a guard before its predicate is; * a register read or written while a variable-latency result for it is on a scoreboard the instruction has not waited on; * a register written while an instruction may still be reading it (a read barrier not waited on, or an unguarded late read: never safe); * a variable-latency result signalling no scoreboard. (scripts/alpha/sbcheck.py over nvdisasm's text was the first form of it.) an asynchronous read no read barrier guards

2150def sm121LowerUnguarded : Nat = 9