Brummel
65e280bb70
Adds --alloc=<gc|bump> to ail build/run. Bump path links a 256MB no-free arena C stub instead of libgc; IR is byte-identical except for the @GC_malloc → @bump_malloc symbol swap. Bench harness times two allocation-heavy workloads (list cons/sum and balanced tree build/walk) under both modes. Numbers (RUNS=5, median of 4): bench_list_sum gc 0.141s bump 0.048s +194% bench_tree_walk gc 0.103s bump 0.041s +151% Bucket: large. ~60% of runtime is Boehm on these workloads — upper bound for any realistic program. Both fixtures hold the heap fully live, so the cost we're seeing is Boehm's allocate path itself, not collection work; that fact narrows the design space for the GC discussion. - crates/ailang-codegen: AllocStrategy enum, three callsites and the IR header parameterised. - crates/ail/src/main.rs: --alloc flag plumbed; bump runtime located + compiled on demand. - runtime/bump.c: 256MB static arena, abort-on-overflow. - examples/bench_list_sum, bench_tree_walk: accumulator-form fixtures (textbook recursive sum was constructor-blocked). - bench/run.sh: harness with Python timing helper (Arch's /usr/bin/time isn't part of the base install). No language-level changes; default --alloc=gc, all 141 workspace tests green, all 5 IR snapshots unchanged, 11 prior fixtures produce identical stdout. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
100 lines
2.9 KiB
Plaintext
100 lines
2.9 KiB
Plaintext
; Bench fixture (Bench iter): linked-list build + sum.
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;
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; Drives the heap allocator hard via a recursive Cons spine. Every
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; ICons cell is one allocation (24 bytes: tag + Int payload + tail).
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; A list of length N therefore costs N allocations. We invoke the
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; workload at three different sizes within a single program run to
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; cover small / medium / large territory.
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;
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; Both `cons_n` (build) and `sum_list` (traverse) are written in
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; accumulator form so the recursive call sits in tail position and
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; can be marked `tail-app`. This is essential at the sizes used here:
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; without `musttail`, three million stack frames overflow the default
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; thread stack and segfault.
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;
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; Workload sizes (hardcoded — AILang has no env-var/argv pipeline):
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;
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; 100_000 * 24 B = 2.4 MB
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; 1_000_000 * 24 B = 24 MB
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; 3_000_000 * 24 B = 72 MB
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;
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; (3M was chosen as the largest size that comfortably fits inside the
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; bump allocator's 256 MB arena with headroom for closure pairs and
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; misc allocations.)
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;
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; Build is allocation-heavy; sum is pure traversal of already-allocated
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; heap (the interesting one for GC pressure / barrier overhead).
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;
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; Expected stdout (one int per line, the sum 0+1+...+(N-1) = N*(N-1)/2):
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; 100_000 -> 4999950000
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; 1_000_000 -> 499999500000
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; 3_000_000 -> 4499998500000
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(module bench_list_sum
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(data IntList
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(ctor INil)
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(ctor ICons (con Int) (con IntList)))
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(fn cons_n_acc
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(doc "Tail-recursive list builder. Result = accumulator-prepended list.")
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(type
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(fn-type
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(params (con Int) (con IntList))
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(ret (con IntList))))
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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 cons_n_acc
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(app - n 1)
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(term-ctor IntList ICons (app - n 1) acc)))))
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(fn cons_n
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(doc "Build [0, 1, ..., n-1] :: IntList. Order doesn't matter for sum.")
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(type
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(fn-type
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(params (con Int))
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(ret (con IntList))))
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(params n)
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(body
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(app cons_n_acc n (term-ctor IntList INil))))
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(fn sum_acc
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(doc "Tail-recursive sum.")
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(type
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(fn-type
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(params (con IntList) (con Int))
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(ret (con Int))))
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(params xs acc)
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(body
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(match xs
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(case (pat-ctor INil) acc)
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(case (pat-ctor ICons h t)
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(tail-app sum_acc t (app + acc h))))))
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(fn sum_list
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(doc "Sum every element. Calls sum_acc with seed 0.")
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(type
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(fn-type
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(params (con IntList))
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(ret (con Int))))
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(params xs)
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(body
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(app sum_acc xs 0)))
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(fn run_one
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(doc "Build a list of length n, sum it, print the sum.")
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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 (app sum_list (app cons_n n)))))
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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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