Add a benchmark for summary prelinking.

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, stderr;
 
 import 'package:analyzer/dart/ast/ast.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/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:analyzer/src/summary/format.dart';
+import 'package:analyzer/src/summary/idl.dart';
+import 'package:analyzer/src/summary/prelink.dart';
 import 'package:analyzer/src/summary/summarize_ast.dart';
 import 'package:kernel/analyzer/loader.dart';
 import 'package:kernel/kernel.dart';
 import 'package:package_config/discovery.dart';
 
 import 'package:front_end/src/scanner/reader.dart';
 import 'package:front_end/src/scanner/scanner.dart';
 import 'package:front_end/src/scanner/token.dart';
 
 /// Cumulative total number of chars scanned.
@@ skipping 41 matching lines @@
       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);
     },
     'unlinked_summarize': () async {
       Set<Source> files = scanReachableFiles(entryUri);
       // TODO(sigmund): replace the warmup with instrumented snapshots.
       for (int i = 0; i < 10; i++) unlinkedSummarizeFiles(files);
+    },
+    'prelinked_summarize': () async {
+      Set<Source> files = scanReachableFiles(entryUri);
+      // TODO(sigmund): replace the warmup with instrumented snapshots.
+      for (int i = 0; i < 10; i++) prelinkedSummarizeFiles(files);
     }
   };
 
   var handler = handlers[bench];
   if (handler == null) {
     // TODO(sigmund): implement the remaining benchmarks.
     print('unsupported bench-id: $bench. Please specify one of the following: '
         '${handlers.keys.join(", ")}');
     exit(1);
   }
@@ skipping 108 matching lines @@
   if (old != scanTotalChars) print('input size changed? ${old} chars');
   report("scan", scanTimer.elapsedMicroseconds);
   report("parse", parseTimer.elapsedMicroseconds);
   report('unlinked summarize', unlinkedSummarizeTimer.elapsedMicroseconds);
   report(
       'unlinked summarize + parse',
       unlinkedSummarizeTimer.elapsedMicroseconds +
           parseTimer.elapsedMicroseconds);
 }
 
+/// Produces prelinked summaries for every file in [files] and reports the time
+/// spent doing so.
+void prelinkedSummarizeFiles(Set<Source> files) {
+  // The code below will record again how many chars are scanned and how long it
+  // takes to scan them, even though we already did so in [scanReachableFiles].
+  // Recording and reporting this twice is unnecessary, but we do so for now to
+  // validate that the results are consistent.
+  scanTimer = new Stopwatch();
+  var old = scanTotalChars;
+  scanTotalChars = 0;
+  parseTimer = new Stopwatch();
+  unlinkedSummarizeTimer = new Stopwatch();
+  var unlinkedSummaries = <Source, UnlinkedUnit>{};
+  for (var source in files) {
+    unlinkedSummaries[source] = unlinkedSummarize(source);
+  }
+  var prelinkTimer = new Stopwatch()..start();
+  for (var source in files) {
+    UnlinkedUnit getSummary(String uri) {
+      var resolvedUri = sources.resolveUri(source, uri);
+      var result = unlinkedSummaries[resolvedUri];
+      if (result == null) {
+        print('Warning: no summary found for: $uri');
+      }
+      return result;
+    }
+
+    UnlinkedPublicNamespace getImport(String uri) =>
+        getSummary(uri)?.publicNamespace;
+    String getDeclaredVariable(String s) => null;
+    prelink(
+        unlinkedSummaries[source], getSummary, getImport, getDeclaredVariable);
+  }
+  prelinkTimer.stop();
+
+  if (old != scanTotalChars) print('input size changed? ${old} chars');
+  report("scan", scanTimer.elapsedMicroseconds);
+  report("parse", parseTimer.elapsedMicroseconds);
+  report('unlinked summarize', unlinkedSummarizeTimer.elapsedMicroseconds);
+  report(
+      'unlinked summarize + parse',
+      unlinkedSummarizeTimer.elapsedMicroseconds +
+          parseTimer.elapsedMicroseconds);
+  report('prelink', prelinkTimer.elapsedMicroseconds);
+}
+
 /// 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);
     }
   }
@@ skipping 72 matching lines @@
     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;
 }