Brummel
07bff24527
Two new throughput fixtures targeting blind spots in the 21'a
corpus:
- bench_closure_chain exercises the build_pair_drop_fn codegen
path (the 18c.4 doubled-braces trigger). Each iteration of
run_loop allocates a {thunk, env} closure pair via the
let-rec-name-as-value escape route. Sizes 10k / 100k / 500k.
rc/bump = 4.14x — materially worse than the 2.91x / 2.59x of
the linear/tree fixtures, exposing that closure work pays the
RC alloc tax twice (pair + env-struct).
- bench_hof_pipeline exercises poly-ADT instantiation and
indirect dispatch via fold_with_fn over List<a>. Sizes 100k /
1M / 3M elements. Ratios essentially match bench_list_sum,
confirming the 13b static-template-plus-ctor-inline design
has zero measurable overhead at this scale.
Baseline file extends from 31 to 47 metrics. The two new fixtures
build clean under all three allocators; the rc-arm build exercises
the per-type drop fn for the closure-pair, providing a tripwire
for any future 18c.4-class IR malformedness.
JOURNAL records both surprises (4.14x closure tax, ~zero HOF/poly
overhead) and explicitly notes the dispersion observation on
explicit_at_rc.p99 — three captures today (357.5 / 294.6 / 251.5)
confirm wide run-to-run variance on that fixture. Methodology
upgrade (n>=10 captures or tighter fixture) deferred to 21'c.
bench/run.sh fixtures array updated. bench/check.py needed no
changes — its parser handles the wider table by metric name.
88 lines
2.9 KiB
Plaintext
88 lines
2.9 KiB
Plaintext
; Bench fixture: HOF + polymorphic ADT pipeline.
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;
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; Builds a polymorphic List<Int> of length n, then folds it with a
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; higher-order function `inc` to compute the sum of incremented
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; elements. Distinct from bench_list_sum:
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; 1. Uses `(data List (vars a) ...)` — polymorphic ADT, exercises
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; the 13b/14a polymorphism-at-runtime path. The Cons cell
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; layout is the same width as bench_list_sum's IntList ICons,
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; but the type-arg substitution is the additional code path.
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; 2. The traversal is via `fold_with_fn` — an HOF taking
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; `(fn-type (params a) (ret (con Int)))` as its first param.
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; Each step calls `(app f h)` — an indirect call through the
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; fn-arg. This is the only fixture that exercises tight-loop
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; indirect dispatch.
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;
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; Build phase is alloc-heavy (n Cons cells); fold phase is
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; dispatch-heavy (n indirect calls). Per-iteration cost should be
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; visibly higher than bench_list_sum's direct sum.
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;
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; Result for size n (using inc(x) = x+1):
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; sum (inc 0) + (inc 1) + ... + (inc (n-1)) = sum 1..n = n*(n+1)/2
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;
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; Sizes:
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; 100_000 -> 5_000_050_000
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; 1_000_000 -> 500_000_500_000
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; 3_000_000 -> 4_500_001_500_000
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(module bench_hof_pipeline
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(data List (vars a)
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(doc "Polymorphic singly-linked list. Same shape as list_map_poly's List, replicated here so the bench fixture is self-contained.")
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(ctor Nil)
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(ctor Cons a (con List a)))
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(fn build_n
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(doc "Build [0, 1, ..., n-1] :: List Int. Tail-recursive accumulator form.")
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(type
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(fn-type
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(params (con Int) (con List (con Int)))
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(ret (con List (con Int)))))
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(params n acc)
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(body
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(if (app == n 0)
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acc
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(tail-app build_n
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(app - n 1)
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(term-ctor List Cons (app - n 1) acc)))))
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(fn inc
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(doc "Add 1 to an Int. Used as the HOF argument to fold_with_fn.")
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(type (fn-type (params (con Int)) (ret (con Int))))
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(params x)
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(body (app + x 1)))
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(fn fold_with_fn
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(doc "Polymorphic foldl-with-mapping. Apply f:(a)->Int to every element of xs, sum into acc. Tail-recursive on (xs, acc); the f arg is forwarded unchanged.")
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(type
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(forall (vars a)
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(fn-type
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(params (fn-type (params a) (ret (con Int)))
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(con List a)
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(con Int))
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(ret (con Int)))))
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(params f xs acc)
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(body
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(match xs
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(case (pat-ctor Nil) acc)
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(case (pat-ctor Cons h t)
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(tail-app fold_with_fn f t (app + acc (app f h)))))))
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(fn run_one
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(doc "Build [0..n-1], fold with inc, print sum of (inc x).")
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(type (fn-type (params (con Int)) (ret (con Unit)) (effects IO)))
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(params n)
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(body
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(do io/print_int
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(app fold_with_fn inc
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(app build_n n (term-ctor List Nil))
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0))))
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(fn main
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(type (fn-type (params) (ret (con Unit)) (effects IO)))
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(params)
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(body
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(seq (app run_one 100000)
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(seq (app run_one 1000000)
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(app run_one 3000000))))))
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