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bench_type_tracking.js
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bench_type_tracking.js
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const now = () => (typeof performance !== 'undefined' && performance.now ? performance.now() : Date.now());
function readScale() {
if (typeof process === 'undefined' || !process || !process.argv) return 1;
const raw = Number(process.argv[2]);
return Number.isFinite(raw) && raw > 0 ? raw : 1;
}
const SCALE = readScale();
const REPEATS = 5;
function opaque(v) {
return v;
}
function runCase(name, rounds, fn) {
// Warm up once with a smaller trip count.
fn(Math.max(1, (rounds / 8) | 0));
const samples = [];
let out = 0;
for (let i = 0; i < REPEATS; i++) {
const t0 = now();
out = fn(rounds);
samples.push(now() - t0);
}
let best = samples[0];
let sum = 0;
for (let i = 0; i < samples.length; i++) {
if (samples[i] < best) best = samples[i];
sum += samples[i];
}
const avg = sum / samples.length;
console.log(`${name}: best ${best.toFixed(2)} ms, avg ${avg.toFixed(2)} ms`);
return { best, avg, out };
}
function reportPair(title, rounds, typedFn, unknownFn) {
console.log(`\n== ${title} (${rounds} rounds) ==`);
const typed = runCase('typed-friendly', rounds, typedFn);
const unknown = runCase('type-unknown ', rounds, unknownFn);
if (typed.out !== unknown.out) {
throw new Error(`${title}: result mismatch (${typed.out} vs ${unknown.out})`);
}
const ratio = unknown.best / typed.best;
const delta = unknown.best - typed.best;
const winner = ratio >= 1 ? 'typed-friendly' : 'type-unknown';
console.log(`speedup: ${ratio.toFixed(2)}x (winner: ${winner}, delta ${delta.toFixed(2)} ms)`);
return typed.out;
}
function forOfArrayTyped(rounds) {
const arr = [
1, 3, 5, 7, 9, 11, 13, 15,
17, 19, 21, 23, 25, 27, 29, 31,
33, 35, 37, 39, 41, 43, 45, 47,
49, 51, 53, 55, 57, 59, 61, 63
];
let sum = 0;
for (let r = 0; r < rounds; r++) {
for (const v of arr) sum += v;
}
return sum;
}
function forOfArrayUnknown(rounds) {
const arr = [
1, 3, 5, 7, 9, 11, 13, 15,
17, 19, 21, 23, 25, 27, 29, 31,
33, 35, 37, 39, 41, 43, 45, 47,
49, 51, 53, 55, 57, 59, 61, 63
];
const iterSrc = opaque(arr);
let sum = 0;
for (let r = 0; r < rounds; r++) {
for (const v of iterSrc) sum += v;
}
return sum;
}
function forOfStringTyped(rounds) {
const str = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
let sum = 0;
for (let r = 0; r < rounds; r++) {
for (const ch of str) sum += ch.length;
}
return sum;
}
function forOfStringUnknown(rounds) {
const str = opaque('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789');
let sum = 0;
for (let r = 0; r < rounds; r++) {
for (const ch of str) sum += ch.length;
}
return sum;
}
function arithmeticTyped(rounds) {
const a = 1.25;
const b = 3.75;
const c = 0.5;
const d = 9.125;
let acc = 0;
for (let i = 0; i < rounds; i++) {
acc = acc + (a * b) - (c / d) + (a + c) - (b - d);
}
return acc;
}
function arithmeticUnknown(rounds) {
const a = opaque(1.25);
const b = opaque(3.75);
const c = opaque(0.5);
const d = opaque(9.125);
let acc = 0;
for (let i = 0; i < rounds; i++) {
acc = acc + (a * b) - (c / d) + (a + c) - (b - d);
}
return acc;
}
function typeofGuardTyped(rounds) {
const x = 123;
let sum = 0;
for (let i = 0; i < rounds; i++) {
if (typeof x === 'number') sum += x;
else sum -= 1;
}
return sum;
}
function typeofGuardUnknown(rounds) {
const x = opaque(123);
let sum = 0;
for (let i = 0; i < rounds; i++) {
if (typeof x === 'number') sum += x;
else sum -= 1;
}
return sum;
}
const roundsForOfArray = Math.max(20000, Math.floor(70000 * SCALE));
const roundsForOfString = Math.max(15000, Math.floor(50000 * SCALE));
const roundsArithmetic = Math.max(500000, Math.floor(2500000 * SCALE));
const roundsTypeof = Math.max(500000, Math.floor(3000000 * SCALE));
console.log('compile-time type tracking benchmark');
console.log(`scale: ${SCALE}`);
console.log(`repeats: ${REPEATS}`);
console.log('usage: ./build/ant tests/bench_type_tracking.js [scale]');
let checksum = 0;
checksum += reportPair('for..of array iterator hint', roundsForOfArray, forOfArrayTyped, forOfArrayUnknown);
checksum += reportPair('for..of string iterator hint', roundsForOfString, forOfStringTyped, forOfStringUnknown);
checksum += reportPair('numeric arithmetic specialization', roundsArithmetic, arithmeticTyped, arithmeticUnknown);
checksum += reportPair('typeof guard folding', roundsTypeof, typeofGuardTyped, typeofGuardUnknown);
console.log(`\nchecksum: ${checksum}`);

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