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// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart=2.9
/// An entrypoint used to run portions of analyzer and measure its performance.
/// TODO(sigmund): rename to 'analyzer_perf.dart' in sync with changes to the
/// perf bots.
/// This file was started to measure the implementation of the front-end when it
/// was based on the analyzer codebase. Now that we are using fasta as the
/// implementation (which is measured in fasta_perf.dart), we still want to
/// measure the analyzer to ensure that there are no regressions when replacing
/// features (e.g. there is no regression from replacing summaries with kernel
/// outlines).
library front_end.tool.perf;
import 'dart:io' show Directory, File, Platform, exit;
import 'package:_fe_analyzer_shared/src/scanner/scanner.dart';
import 'package:analyzer/dart/analysis/features.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/error/listener.dart';
import 'package:analyzer/file_system/file_system.dart' show Folder;
import 'package:analyzer/file_system/physical_file_system.dart';
import 'package:analyzer/src/context/packages.dart';
import 'package:analyzer/src/dart/sdk/sdk.dart' show FolderBasedDartSdk;
import 'package:analyzer/src/file_system/file_system.dart';
import 'package:analyzer/src/generated/parser.dart';
import 'package:analyzer/src/generated/source.dart';
import 'package:analyzer/src/generated/source_io.dart';
import 'package:analyzer/src/source/package_map_resolver.dart';
import 'package:path/path.dart' as path;
main(List<String> args) async {
// TODO(sigmund): provide sdk folder as well.
if (args.length < 2) {
print('usage: perf.dart <bench-id> <entry.dart>');
var bench = args[0];
var entryUri = Uri.base.resolve(args[1]);
await setup(path.fromUri(entryUri));
Set<Source> files = scanReachableFiles(entryUri);
var handlers = {
'scan': () async => scanFiles(files),
'parse': () async => parseFiles(files),
var handler = handlers[bench];
if (handler == null) {
print('unsupported bench-id: $bench. Please specify one of the following: '
'${handlers.keys.join(", ")}');
// TODO(sigmund): replace the warmup with instrumented snapshots.
int iterations = bench.contains('kernel_gen') ? 2 : 10;
for (int i = 0; i < iterations; i++) {
var totalTimer = new Stopwatch()..start();
print('== iteration $i');
await handler();
report('total', totalTimer.elapsedMicroseconds);
/// Cumulative time spent parsing.
Stopwatch parseTimer = new Stopwatch();
/// Cumulative time spent scanning.
Stopwatch scanTimer = new Stopwatch();
/// Size of all sources.
int inputSize = 0;
/// Factory to load and resolve app, packages, and sdk sources.
SourceFactory sources;
/// Path to the root of the built SDK that is being used to execute this script.
final _sdkPath = _findSdkPath();
/// Add to [files] all sources reachable from [start].
void collectSources(Source start, Set<Source> files) {
if (!files.add(start)) return;
var unit = parseDirectives(start);
for (var directive in unit.directives) {
if (directive is UriBasedDirective) {
var next = sources.resolveUri(start, directive.uri.stringValue);
collectSources(next, files);
/// Uses the diet-parser to parse only directives in [source].
CompilationUnit parseDirectives(Source source) {
var token = tokenize(source);
var parser = new Parser(
featureSet: FeatureSet.latestLanguageVersion(),
return parser.parseDirectives(token);
/// Parses every file in [files] and reports the time spent doing so.
void parseFiles(Set<Source> files) {
scanTimer = new Stopwatch();
parseTimer = new Stopwatch();
for (var source in files) {
report('scan', scanTimer.elapsedMicroseconds);
report('parse', parseTimer.elapsedMicroseconds);
/// Parse the full body of [source] and return it's compilation unit.
CompilationUnit parseFull(Source source) {
var token = tokenize(source);
var parser = new Parser(
featureSet: FeatureSet.latestLanguageVersion(),
var unit = parser.parseCompilationUnit(token);
return unit;
/// Report that metric [name] took [time] micro-seconds to process
/// [inputSize] characters.
void report(String name, int time) {
StringBuffer sb = new StringBuffer();
String padding = ' ' * (20 - name.length);
sb.write('$name:$padding $time us, ${time ~/ 1000} ms');
String invSpeed = (time * 1000 / inputSize).toStringAsFixed(2);
sb.write(', $invSpeed ns/char');
/// Scans every file in [files] and reports the time spent doing so.
void scanFiles(Set<Source> files) {
// `tokenize` records how many chars are scanned and how long it takes to scan
// them. As this function is called repeatedly when running as a benchmark, we
// make sure to clear the data and compute it again every time.
scanTimer = new Stopwatch();
for (var source in files) {
report('scan', scanTimer.elapsedMicroseconds);
/// Load and scans all files we need to process: files reachable from the
/// entrypoint and all core libraries automatically included by the VM.
Set<Source> scanReachableFiles(Uri entryUri) {
var files = new Set<Source>();
var loadTimer = new Stopwatch()..start();
scanTimer = new Stopwatch();
collectSources(sources.forUri2(entryUri), files);
var libs = [
for (var lib in libs) {
collectSources(sources.forUri(lib), files);
inputSize = 0;
for (var s in files) {
inputSize +=;
print('input size: ${inputSize} chars');
var loadTime = loadTimer.elapsedMicroseconds - scanTimer.elapsedMicroseconds;
report('load', loadTime);
report('scan', scanTimer.elapsedMicroseconds);
return files;
/// Sets up analyzer to be able to load and resolve app, packages, and sdk
/// sources.
Future setup(String path) async {
var provider = PhysicalResourceProvider.INSTANCE;
var packages = findPackagesFrom(
var packageMap = <String, List<Folder>>{};
for (var package in packages.packages) {
packageMap[] = [package.libFolder];
sources = new SourceFactory([
new ResourceUriResolver(provider),
new PackageMapUriResolver(provider, packageMap),
new DartUriResolver(
new FolderBasedDartSdk(provider, provider.getFolder(_sdkPath))),
/// Scan [source] and return the first token produced by the scanner.
Token tokenize(Source source) {
// TODO(sigmund): is there a way to scan from a random-access-file without
// first converting to String?
ScannerResult result =
scanString(, includeComments: false);
var token = result.tokens;
if (result.hasErrors) {
// Ignore errors.
while (token is ErrorToken) {
token =;
return token;
String _findSdkPath() {
var executable = Platform.resolvedExecutable;
var executableDir = path.dirname(executable);
for (var candidate in [
path.join(executableDir, 'dart-sdk')
]) {
if (new File(path.join(candidate, 'lib', 'libraries.json')).existsSync()) {
return candidate;
// Not found; guess "sdk" relative to the current directory.
return new Directory('sdk').absolute.path;