Brummel
75f7fda788
Closes the apples-to-apples gap from 21'e. Adds: - examples/bench_list_sum_explicit.ailx — same algorithm and sizes as bench_list_sum, fully (borrow)/(own)/(drop-iterative) annotated so codegen emits proper inc/dec instrumentation. - bench/reference/list_sum_explicit_free.c — same algorithm with explicit free() walking the chain after sum. The full alloc+dec vs malloc+free comparison reveals two non- trivial conclusions: 1. AILang's full RC pipeline is only 26% slower than glibc malloc+free on this workload (rc/c = 1.26x). The implicit- mode comparison's 1.42x was misleading — it counted neither pipeline's free path. The fair ratio is 1.26x, materially better than the previous read. 2. RC's dec is cheaper per cell than glibc free(). AILang dec-tax: ~3 ns/cell. C free-tax: ~5.5 ns/cell. Plausible cause: ailang_rc_dec operates on a known-shape cell with a fixed-offset refcount and a static per-type drop fn — no free-list bucketing, no header introspection, no global lock. bump's advantage expresses fully: bench_list_sum_explicit.bump/c = 0.42x means AILang at bump is 2.4x faster than C malloc+free. Sets a useful upper bound on a slab/pool RC allocator's potential. The 21'-family arc — bench-regression infrastructure — is now substantively complete: 21'a (bench/check.py), 21'b (corpus widening), 21'c (compile_check.py), 21'd (pure-compute fixtures + harness hardening), 21'e (cross-language hand-C), 21'f (explicit apples-to-apples). 63 runtime metrics + 18 compile metrics + 25 cross-lang metrics under regression coverage. Any future iter that regresses any axis beyond tolerance gets caught at the next family close. Remaining queue is back to substantive language work — Family 21 (typeclasses / polymorphic ADTs at runtime / pattern-binding generalisation) is now an orchestrator-level fork that needs direct user input.