Brummel
c897d2eef0
Closes the question CLAUDE.md has carried since day one ("LLVM-
linkable, performance is extremely important") with data. Hand-C
variants of the four bench fixtures, compiled with clang -O2,
each carefully matching the AILang algorithm and explicitly
documenting representation differences (cell width, leak policy)
that affect the ratio.
Three substantive findings:
1. Pure-compute parity with C: bench_compute_collatz runs at
AILang/C = 0.99x across both allocators. AILang's IR composes
with LLVM's optimizer at the same level a hand-C source does.
This is the LLVM-linkable performance claim, backed by data
for the first time. bench_compute_intsum (1.05-1.18x) confirms.
2. AILang bump beats glibc malloc 2x on linear allocation:
bench_list_sum.bump/c = 0.50x. Bump's two-instruction inline
fastpath outperforms glibc's free-list-managed malloc on
no-free workloads. Quantitatively measured for the first time.
3. RC overhead vs C malloc quantified: bench_list_sum.rc/c =
1.49x, bench_tree_walk.rc/c = 2.61x. The 8-byte refcount
header + zero-init + libc backing add 50-160% over glibc
malloc on these implicit-mode workloads. Explicit-mode + a
free()-adding C variant (21'f, queued) will close the
apples-to-apples gap on dec-cost.
CLAUDE.md updated to list bench/cross_lang.py as the third
tidy-iter gate alongside bench/check.py and bench/compile_check.py.
20 new metrics in bench/baseline_cross_lang.json with 12-15%
tolerances (cross-language ratios are inherently noisier than
within-AILang ratios — two compiler stacks contribute variance).
69 lines
2.0 KiB
C
69 lines
2.0 KiB
C
// Hand-C reference for bench_list_sum.
|
|
//
|
|
// Same algorithm as examples/bench_list_sum.ailx — build a linked list
|
|
// of [0, 1, ..., N-1] via prepending, then sum by linear traversal.
|
|
// Three workload sizes: 100k / 1M / 3M cells, matching the AILang
|
|
// fixture exactly so the AILang/C wall-time ratio is fair.
|
|
//
|
|
// Cell layout: { long head; struct cell *tail; } — 16 bytes (8 head
|
|
// + 8 pointer). AILang's IntList ICons cell is wider (tag + payload +
|
|
// tail = 24 bytes) because the runtime carries a constructor tag for
|
|
// the discriminated-union. The 1.5x size difference is one of the
|
|
// real costs of the discriminated-union representation; quoting the
|
|
// raw ratio without naming this is the wrong comparison.
|
|
//
|
|
// Memory policy: this reference uses malloc and DELIBERATELY DOES
|
|
// NOT FREE. That matches AILang's bench_list_sum running under
|
|
// --alloc=rc with implicit-mode params (cells leak by design — the
|
|
// 18c.3 known debt). The fair comparison is therefore:
|
|
// AILang --alloc=rc (implicit-mode, leaks) vs. this C (leaks)
|
|
// A future iter that ships explicit-mode bench_list_sum + a free()-
|
|
// adding C variant would close the apples-to-apples gap on the
|
|
// dec-cost axis.
|
|
//
|
|
// Build: clang -O2 -o list_sum list_sum.c
|
|
// Expected stdout (one int per line):
|
|
// 4999950000
|
|
// 499999500000
|
|
// 4499998500000
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
typedef struct cell {
|
|
long head;
|
|
struct cell *tail;
|
|
} cell_t;
|
|
|
|
static cell_t *cons_n(long n) {
|
|
cell_t *acc = NULL;
|
|
for (long i = n - 1; i >= 0; i--) {
|
|
cell_t *c = (cell_t *) malloc(sizeof(cell_t));
|
|
c->head = i;
|
|
c->tail = acc;
|
|
acc = c;
|
|
}
|
|
return acc;
|
|
}
|
|
|
|
static long sum_list(const cell_t *xs) {
|
|
long acc = 0;
|
|
while (xs) {
|
|
acc += xs->head;
|
|
xs = xs->tail;
|
|
}
|
|
return acc;
|
|
}
|
|
|
|
static void run_one(long n) {
|
|
const cell_t *xs = cons_n(n);
|
|
printf("%ld\n", sum_list(xs));
|
|
}
|
|
|
|
int main(void) {
|
|
run_one(100000);
|
|
run_one(1000000);
|
|
run_one(3000000);
|
|
return 0;
|
|
}
|