add kernel generation to the front_end/tool/perf script

pkg/front_end/tool/perf.dart

 // 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.
 
 /// An entrypoint used to run portions of front_end and measure its performance.
 library front_end.tool.perf;
 
 import 'dart:async';
-import 'dart:io' show exit;
+import 'dart:io' show exit, stderr;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/file_system/file_system.dart' show ResourceUriResolver;
 import 'package:analyzer/file_system/physical_file_system.dart'
     show PhysicalResourceProvider;
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/context/builder.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/dart/sdk/sdk.dart' show FolderBasedDartSdk;
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
+import 'package:kernel/analyzer/loader.dart';
+import 'package:kernel/kernel.dart';
 import 'package:package_config/discovery.dart';
 
 /// Cumulative total number of chars scanned.
 int scanTotalChars = 0;
 
 /// Cumulative time spent scanning.
 Stopwatch scanTimer = new Stopwatch();
 
 /// Factory to load and resolve app, packages, and sdk sources.
 SourceFactory sources;
 
 main(List<String> args) async {
   // TODO(sigmund): provide sdk folder as well.
   if (args.length < 2) {
     print('usage: perf.dart <bench-id> <entry.dart>');
     exit(1);
   }
   var totalTimer = new Stopwatch()..start();
 
   var bench = args[0];
   var entryUri = Uri.base.resolve(args[1]);
 
   await setup(entryUri);
 
-  if (bench == 'scan') {
-    Set<Source> files = scanReachableFiles(entryUri);
-    // TODO(sigmund): consider replacing the warmup with instrumented snapshots.
-    for (int i = 0; i < 10; i++) scanFiles(files);
-  } else if (bench == 'parse') {
-    Set<Source> files = scanReachableFiles(entryUri);
-    // TODO(sigmund): consider replacing the warmup with instrumented snapshots.
-    for (int i = 0; i < 10; i++) parseFiles(files);
-  } else {
-    print('unsupported bench-id: $bench. Please specify "scan" or "parse"');
+  var handlers = {
+    'scan': () async {
+      Set<SourceFile> files = scanReachableFiles(entryUri);
+      // TODO(sigmund): replace the warmup with instrumented snapshots.
+      for (int i = 0; i < 10; i++) scanFiles(files);
+    },
+    'parse': () async {
+      Set<SourceFile> files = scanReachableFiles(entryUri);
+      // TODO(sigmund): replace the warmup with instrumented snapshots.
+      for (int i = 0; i < 10; i++) parseFiles(files);
+    },
+    'kernel_gen_e2e': () async {
+      // TODO(sigmund): remove. This is used to compute the input size, we
+      // should extract input size from frontend instead.
+      scanReachableFiles(entryUri);
+      // TODO(sigmund): replace this warmup. Note that for very large programs,
+      // the GC pressure on the VM seems to make this worse with time (maybe we
+      // are leaking memory?). That's why we run it twice and not 10 times.
+      for (int i = 0; i < 2; i++) await generateKernel(entryUri);
+    },
+  };
+
+  var handler = handlers[bench];
+  if (handler == null) {
     // TODO(sigmund): implement the remaining benchmarks.
+    print('unsupported bench-id: $bench. Please specify one of the following: '
+        '${handler.keys.join(", ")}');
     exit(1);
   }
+  await handler();
 
   totalTimer.stop();
   report("total", totalTimer.elapsedMicroseconds);
 }
 
 /// Sets up analyzer to be able to load and resolve app, packages, and sdk
 /// sources.
 Future setup(Uri entryUri) async {
   var provider = PhysicalResourceProvider.INSTANCE;
   var packageMap = new ContextBuilder(provider, null, null)
@@ skipping 122 matching lines @@
 }
 
 /// Report that metric [name] took [time] micro-seconds to process
 /// [scanTotalChars] characters.
 void report(String name, int time) {
   var sb = new StringBuffer();
   sb.write('$name: $time us, ${time ~/ 1000} ms');
   sb.write(', ${scanTotalChars * 1000 ~/ time} chars/ms');
   print('$sb');
 }
+
+// TODO(sigmund): replace this once kernel is produced by the frontend directly.
+Future<Program> generateKernel(Uri entryUri) async {
+  var dartkTimer = new Stopwatch()..start();
+  var options = new DartOptions(strongMode: false, sdk: 'sdk');
+  var packages =
+      await createPackages(options.packagePath, discoveryPath: entryUri.path);
+  var repository = new Repository();
+  DartLoader loader = new DartLoader(repository, options, packages);
+
+  Program program = loader.loadProgram(entryUri.path);
+  List errors = loader.errors;
+  if (errors.isNotEmpty) {
+    const int errorLimit = 100;
+    stderr.writeln(errors.take(errorLimit).join('\n'));
+    if (errors.length > errorLimit) {
+      stderr.writeln('[error] ${errors.length - errorLimit} errors not shown');
+    }
+  }
+  dartkTimer.stop();
+  report("kernel_gen_e2e", dartkTimer.elapsedMicroseconds);
+  return program;
+}