pub static PRIME_SPLIT_CHUNKS: AtomicUsizeExpand description
SPLIT-LIVENESS COUNTER for the prime stage split: bumped ONCE per prime chunk that
actually executed the per-stage walk. The prime-split-gate requires this to ADVANCE
during its split arm — bit-identity of two identical UNSPLIT walks is vacuous, so a gate
that only compared bits would go green while the walker doesn’t exist. With the counter,
the gate is RED until the walker lands (the tickinv35 pattern: the gate exists and fails
before the mechanism does). Relaxed ordering: single-threaded host issue, count-only.