From e080f399ca0182ef60628f06684df2e246002172 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 3 Apr 2026 13:15:49 -0400
Subject: [PATCH] break out report generation

---
 benchmarking/compare/generate-report.js | 81 +++++++++++++++++++++++++
 benchmarking/compare/index.js           | 70 +--------------------
 2 files changed, 83 insertions(+), 68 deletions(-)
 create mode 100644 benchmarking/compare/generate-report.js

diff --git a/benchmarking/compare/generate-report.js b/benchmarking/compare/generate-report.js
new file mode 100644
index 0000000000..a61f58909b
--- /dev/null
+++ b/benchmarking/compare/generate-report.js
@@ -0,0 +1,81 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import { pathToFileURL } from 'node:url';
+
+export function generate_report(outdir) {
+	const result_files = fs
+		.readdirSync(outdir)
+		.filter((file) => file.endsWith('.json'))
+		.sort((a, b) => a.localeCompare(b));
+
+	const branches = result_files.map((file) => file.slice(0, -5));
+	const results = result_files.map((file) =>
+		JSON.parse(fs.readFileSync(`${outdir}/${file}`, 'utf-8'))
+	);
+
+	if (results.length === 0) {
+		console.error(`No result files found in ${outdir}`);
+		process.exit(1);
+	}
+
+	const report_file = path.join(outdir, 'report.txt');
+
+	fs.writeFileSync(report_file, '');
+
+	const write = (str) => {
+		fs.appendFileSync(report_file, str + '\n');
+		console.log(str);
+	};
+
+	for (let i = 0; i < branches.length; i += 1) {
+		write(`${char(i)}: ${branches[i]}`);
+	}
+
+	write('');
+
+	for (let i = 0; i < results[0].length; i += 1) {
+		write(`${results[0][i].benchmark}`);
+
+		for (const metric of ['time', 'gc_time']) {
+			const times = results.map((result) => +result[i][metric]);
+			let min = Infinity;
+			let max = -Infinity;
+			let min_index = -1;
+
+			for (let b = 0; b < times.length; b += 1) {
+				const time = times[b];
+
+				if (time < min) {
+					min = time;
+					min_index = b;
+				}
+
+				if (time > max) {
+					max = time;
+				}
+			}
+
+			if (min !== 0) {
+				write(`  ${metric}: fastest is ${char(min_index)} (${branches[min_index]})`);
+				times.forEach((time, b) => {
+					const SIZE = 20;
+					const n = Math.round(SIZE * (time / max));
+
+					write(`    ${char(b)}: ${'◼'.repeat(n)}${' '.repeat(SIZE - n)} ${time.toFixed(2)}ms`);
+				});
+			}
+		}
+
+		write('');
+	}
+}
+
+function char(i) {
+	return String.fromCharCode(97 + i);
+}
+
+if (import.meta.url === pathToFileURL(process.argv[1]).href) {
+	const outdir = path.resolve(process.argv[1], '../.results');
+
+	generate_report(outdir);
+}
diff --git a/benchmarking/compare/index.js b/benchmarking/compare/index.js
index 100d98a767..9064ee7da9 100644
--- a/benchmarking/compare/index.js
+++ b/benchmarking/compare/index.js
@@ -3,6 +3,7 @@ import path from 'node:path';
 import { execSync, fork } from 'node:child_process';
 import { fileURLToPath } from 'node:url';
 import { safe } from '../utils.js';
+import { generate_report } from './generate-report.js';
 
 // if (execSync('git status --porcelain').toString().trim()) {
 // 	console.error('Working directory is not clean');
@@ -12,7 +13,6 @@ import { safe } from '../utils.js';
 const filename = fileURLToPath(import.meta.url);
 const runner = path.resolve(filename, '../runner.js');
 const outdir = path.resolve(filename, '../.results');
-const report_file = `${outdir}/report.txt`;
 
 fs.mkdirSync(outdir, { recursive: true });
 
@@ -85,70 +85,4 @@ if (PROFILE_DIR !== null) {
 	console.log(`\nCPU profiles written to ${PROFILE_DIR}`);
 }
 
-const result_files = fs
-	.readdirSync(outdir)
-	.filter((file) => file.endsWith('.json'))
-	.sort((a, b) => a.localeCompare(b));
-
-const branches = result_files.map((file) => file.slice(0, -5));
-const results = result_files.map((file) =>
-	JSON.parse(fs.readFileSync(`${outdir}/${file}`, 'utf-8'))
-);
-
-if (results.length === 0) {
-	console.error(`No result files found in ${outdir}`);
-	process.exit(1);
-}
-
-fs.writeFileSync(report_file, '');
-
-const write = (str) => {
-	fs.appendFileSync(report_file, str + '\n');
-	console.log(str);
-};
-
-for (let i = 0; i < branches.length; i += 1) {
-	write(`${char(i)}: ${branches[i]}`);
-}
-
-write('');
-
-for (let i = 0; i < results[0].length; i += 1) {
-	write(`${results[0][i].benchmark}`);
-
-	for (const metric of ['time', 'gc_time']) {
-		const times = results.map((result) => +result[i][metric]);
-		let min = Infinity;
-		let max = -Infinity;
-		let min_index = -1;
-
-		for (let b = 0; b < times.length; b += 1) {
-			const time = times[b];
-
-			if (time < min) {
-				min = time;
-				min_index = b;
-			}
-
-			if (time > max) {
-				max = time;
-			}
-		}
-
-		if (min !== 0) {
-			write(`  ${metric}: fastest is ${char(min_index)} (${branches[min_index]})`);
-			times.forEach((time, b) => {
-				const SIZE = 20;
-				const n = Math.round(SIZE * (time / max));
-
-				write(`    ${char(b)}: ${'◼'.repeat(n)}${' '.repeat(SIZE - n)} ${time.toFixed(2)}ms`);
-			});
-		}
-	}
-
-	write('');
-}
-
-function char(i) {
-	return String.fromCharCode(97 + i);
-}
+generate_report(outdir);