Collate stacks in test output

pkg/compiler/tool/status_files/rank_stacks.dart

Index: pkg/compiler/tool/status_files/rank_stacks.dart
diff --git a/pkg/compiler/tool/status_files/rank_stacks.dart b/pkg/compiler/tool/status_files/rank_stacks.dart
new file mode 100644
index 0000000000000000000000000000000000000000..31345e037b721d68eb82ca505a6f4a586e4aabe7
--- /dev/null
+++ b/pkg/compiler/tool/status_files/rank_stacks.dart
@@ -0,0 +1,117 @@
+// Copyright (c) 2017, 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.
+
+/*
+Usage:
+
+  $ tools/test.py -m release                         \
+      -c dart2js -r d8 --dart2js-batch --report      \
+      --host-checked                                 \
+      --dart2js_options="--library-root=out/ReleaseX64/dart-sdk/ --use-kernel" \
+      language corelib library_2 corelib_2           \
+      dart2js_native dart2js_extra                   \
+      2>&1 > LOG
+
+  $ sdk/bin/dart pkg/compiler/tool/status_files/rank_stacks.dart LOG > STACKS.txt
+*/
+
+import 'dart:io';
+
+import 'log_parser.dart';
+import 'record.dart';
+
+// TODO(sra): Allow command-line setting of these parameters.
+const STACK_PRINT_LENGTH = 12;
+const HOW_MANY_STACKS = 30;
+
+main(args) {
+  String text;
+
+  for (String arg in args) {
+    // Parse options.
+
+    if (text == null) {
+      var uri = Uri.base.resolve(arg);
+      var file = new File.fromUri(uri);
+      if (!file.existsSync()) {
+        print('File not found: $file.');
+        exit(1);
+      }
+      text = file.readAsStringSync();
+    } else {
+      print("Extra file argument '$arg'.");
+      exit(1);
+    }
+  }
+
+  if (text == null) {
+    print('No input file.');
+    exit(1);
+  }
+
+  var records = parse(text);
+  var trie = new TrieNode(null);
+  for (var record in records) {
+    enter(record, 0, trie);
+  }
+
+  var leaves = trieLeaves(trie).toList();
+  leaves.sort((a, b) => b.length.compareTo(a.length));
+  for (var leaf in leaves.take(HOW_MANY_STACKS)) {
+    print('');
+    var examples = leaf.members.map((r) => r.fullReason).toSet().toList();
+    examples.sort();
+    print('${leaf.length} of:');
+    for (var example in examples) {
+      var count = leaf.members.where((r) => r.fullReason == example).length;
+      var countAligned = '$count'.padLeft(6);
+      if (examples.length == 1) countAligned = '     .';
+      var indentedExample = '\t' + example.replaceAll('\n', '\n\t');
+      print('${countAligned}${indentedExample}');
+    }
+
+    for (var line in leaf.members.first.stack.take(STACK_PRINT_LENGTH)) {
+      print('  $line');
+    }
+  }
+}
+
+class TrieNode {
+  final int depth;
+  final String key;
+  final Map<String, TrieNode> map = <String, TrieNode>{};
+  final List<Record> members = <Record>[];
+
+  int get length => members.length;
+
+  TrieNode(this.key, [this.depth = 0]);
+
+  String toString() => 'TrieNode(#$length)';
+}
+
+void enter(Record record, int depth, TrieNode root) {
+  root.members.add(record);
+  if (depth >= record.stack.length) return;
+  var key = record.stack[depth];
+  var node = root.map[key] ??= new TrieNode(key, depth + 1);
+  enter(record, depth + 1, node);
+}
+
+void printTrie(TrieNode node) {
+  var indent = '  ' * node.depth;
+  print('${indent} ${node.length} ${node.key}');
+  for (var key in node.map.keys) {
+    printTrie(node.map[key]);
+  }
+}
+
+trieLeaves(node) sync* {
+  if (node.map.isEmpty) {
+    yield node;
+  } else {
+    for (var v in node.map.values) {
+      yield* trieLeaves(v);
+    }
+  }
+}