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bench_property_hotspots.js
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bench_property_hotspots.js
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function nowMs() {
if (typeof performance !== 'undefined' && performance && typeof performance.now === 'function') {
return performance.now();
}
return Date.now();
}
function parseScale() {
if (typeof process === 'undefined' || !process || !process.argv) return 1;
const raw = Number(process.argv[2]);
return Number.isFinite(raw) && raw > 0 ? raw : 1;
}
function percentile(sorted, p) {
if (sorted.length === 0) return 0;
if (sorted.length === 1) return sorted[0];
const pos = (sorted.length - 1) * p;
const base = Math.floor(pos);
const frac = pos - base;
const next = sorted[base + 1];
if (next === undefined) return sorted[base];
return sorted[base] + (next - sorted[base]) * frac;
}
function stableNumericSort(values) {
const out = values.slice();
for (let i = 1; i < out.length; i++) {
const x = out[i];
let j = i - 1;
while (j >= 0 && out[j] > x) {
out[j + 1] = out[j];
j--;
}
out[j + 1] = x;
}
return out;
}
const SCALE = parseScale();
const BENCH_WARMUP_RUNS = 2;
const BENCH_SAMPLE_RUNS = 7;
let benchSink = 0;
function scaledIters(base) {
return Math.max(1, Math.floor(base * SCALE));
}
function section(title) {
console.log('\n=== ' + title + ' ===');
}
function bench(label, fn, iters) {
const warmupIters = Math.max(1, Math.min(iters, Math.max(10_000, (iters / 4) | 0)));
for (let i = 0; i < BENCH_WARMUP_RUNS; i++) benchSink ^= fn(warmupIters) | 0;
let result = 0;
const samples = [];
for (let i = 0; i < BENCH_SAMPLE_RUNS; i++) {
const t0 = nowMs();
const r = fn(iters);
const dt = nowMs() - t0;
if (i === 0) result = r;
samples.push(dt);
}
const sorted = stableNumericSort(samples);
const min = sorted[0];
const med = percentile(sorted, 0.5);
const p95 = percentile(sorted, 0.95);
const max = sorted[sorted.length - 1];
const opsPerMs = med > 0 ? (iters / med).toFixed(2) : 'inf';
benchSink ^= result | 0;
console.log(
label +
': median ' + med.toFixed(2) + 'ms (' + opsPerMs + ' ops/ms)' +
', p95 ' + p95.toFixed(2) + 'ms' +
', min ' + min.toFixed(2) + 'ms' +
', max ' + max.toFixed(2) + 'ms' +
' result=' + result
);
}
function benchCfuncProtoCallApply(n) {
const fn = parseInt;
let sum = 0;
for (let i = 0; i < n; i++) {
if (fn.call) sum++;
if (fn.apply) sum++;
}
return sum;
}
function benchCfuncProtoBind(n) {
const fn = parseInt;
let sum = 0;
for (let i = 0; i < n; i++) {
if (fn.bind) sum++;
}
return sum;
}
const DATA_DESC = {
value: 1,
writable: true,
enumerable: true,
configurable: true,
};
function benchDefinePropertyFresh(n) {
let sum = 0;
for (let i = 0; i < n; i++) {
const obj = {};
Object.defineProperty(obj, 'x', DATA_DESC);
sum += obj.x;
}
return sum;
}
const ACCESSOR_DESC = {
get() { return 1; },
set(v) { benchSink ^= v | 0; },
enumerable: true,
configurable: true,
};
function benchDefineAccessorFresh(n) {
let sum = 0;
for (let i = 0; i < n; i++) {
const obj = {};
Object.defineProperty(obj, 'x', ACCESSOR_DESC);
sum += obj.x;
}
return sum;
}
function benchWithGet(n) {
const scopeObj = { x: 1 };
let sum = 0;
with (scopeObj) {
for (let i = 0; i < n; i++) sum += x;
}
return sum;
}
function makeReusableRangeIterable(limit) {
return {
[Symbol.iterator]() {
let i = 0;
const result = { done: false, value: 0 };
return {
next() {
if (i < limit) {
result.done = false;
result.value = i++;
} else {
result.done = true;
result.value = undefined;
}
return result;
}
};
}
};
}
function benchForOfReusableResult(n) {
let sum = 0;
for (const v of makeReusableRangeIterable(n)) sum += v;
return sum;
}
function benchArrayLiteralCreate(n) {
let sum = 0;
for (let i = 0; i < n; i++) {
const arr = [];
sum += arr.length;
}
return sum;
}
function benchObjectLiteralCreate(n) {
let sum = 0;
for (let i = 0; i < n; i++) {
const obj = {};
if (obj) sum++;
}
return sum;
}
function benchStringProtoDotRead(n) {
const str = ' hello ';
let sum = 0;
for (let i = 0; i < n; i++) {
if (str.trim) sum++;
if (str.toUpperCase) sum++;
}
return sum;
}
function benchNumberProtoDotRead(n) {
const num = 123.456;
let sum = 0;
for (let i = 0; i < n; i++) {
if (num.toFixed) sum++;
if (num.toString) sum++;
}
return sum;
}
function benchComputedMissingShortKey(n) {
const obj = {};
const key = 'missing';
let sum = 0;
for (let i = 0; i < n; i++) {
if (obj[key] === undefined) sum++;
}
return sum;
}
function benchComputedMissingLongKey(n) {
const obj = {};
const key = 'missing_property_name_that_is_long_enough_to_force_a_heap_alloc_in_sv_getprop_fallback_len_0123456789';
let sum = 0;
for (let i = 0; i < n; i++) {
if (obj[key] === undefined) sum++;
}
return sum;
}
console.log('property hotspot benchmark');
console.log('scale=' + SCALE);
section('1. lkp_proto T_CFUNC branch re-interns');
console.log('sanity parseInt.call=' + (typeof parseInt.call));
bench('cfunc_proto_call_apply', benchCfuncProtoCallApply, scaledIters(2_000_000));
bench('cfunc_proto_bind', benchCfuncProtoBind, scaledIters(1_500_000));
section('2. ensure_string_shape_slot miss path');
console.log('sanity defineProperty=' + (typeof Object.defineProperty));
bench('defineProperty_fresh_data', benchDefinePropertyFresh, scaledIters(300_000));
bench('defineProperty_fresh_accessor', benchDefineAccessorFresh, scaledIters(200_000));
section('3. with lookup existence-check plus re-fetch');
console.log('sanity with=' + benchWithGet(3));
bench('with_get_var', benchWithGet, scaledIters(1_500_000));
section('4. iterator done/value generic reads');
console.log('sanity for_of=' + benchForOfReusableResult(8));
bench('for_of_reusable_result', benchForOfReusableResult, scaledIters(600_000));
section('5. ctor.prototype lookup on allocation');
console.log('sanity literals=' + (benchArrayLiteralCreate(3) + benchObjectLiteralCreate(3)));
bench('array_literal_create', benchArrayLiteralCreate, scaledIters(2_000_000));
bench('object_literal_create', benchObjectLiteralCreate, scaledIters(2_000_000));
section('6. primitive proto reads through generic path');
console.log('sanity primitive=' + (benchStringProtoDotRead(2) + benchNumberProtoDotRead(2)));
bench('string_proto_dot_read', benchStringProtoDotRead, scaledIters(2_000_000));
bench('number_proto_dot_read', benchNumberProtoDotRead, scaledIters(2_000_000));
section('7. computed missing-key reads through sv_getprop_fallback_len');
console.log('sanity computed=' + (benchComputedMissingShortKey(2) + benchComputedMissingLongKey(2)));
bench('computed_missing_short_key', benchComputedMissingShortKey, scaledIters(2_000_000));
bench('computed_missing_long_key', benchComputedMissingLongKey, scaledIters(1_000_000));
console.log('\nbenchSink=' + benchSink);

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bench_property_hotspots.js (6 KB)

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