From the S76 func_80180B3C agent (297 ins, 82 -> 23). Three prior attempts
steered sched1 by reordering source and inferring the cost model from .sched
RTL order; cc1 -dS prints the ready list WITH priorities, so it can be read
instead of reconstructed.
Two reusable findings: register pins beat schedule-chasing when the diff
walks a register chain (four pins carried 44 -> 23 after three attempts had
treated the chain as downstream of the schedule) — and statement order was
inert BEFORE the pins and live after, so an 'order does nothing' measurement
is only valid for the allocation it was taken under. Second, sched1's
birthing boost was proven to be the dial and is still unturnable here:
every spelling making the mask single-set lets combine fold the subreg and
lose four instructions. A dial you can prove and cannot turn is permuter
fuel, not a wall.
Drew T
b4b2400d65