Disconnects code objects from infrequently used unoptimized functions.

tests/standalone/code_collection_test.dart

+// Copyright (c) 2013, 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 test program testing code GC.
+
+import "package:expect/expect.dart";
+import "dart:async";
+import "dart:io";
+
+
+int foo(int x) {
+  x = x + 1;
+  return x;
+}
+
+
+List<int> bar() {
+  // A couple of big allocations trigger GC.
+  var l = new List.filled(700000, 7);
+  return l;
+}
+
+
+doTest() {
+ var i = 0;
+  foo(1);  // Initial call to compile.
+  // Time passes, GC runs, foo's code is dropped.
+  var ms = const Duration(milliseconds: 100);
+  var t = new Timer.periodic(ms, (timer) {
+    i++;
+    bar();
+    if (i > 1) {
+      timer.cancel();
+      // foo is called again to make sure we can still run it even after
+      // its code has been detached.
+      foo(2);
+    }
+  });
+}
+
+
+main() {
+  var opts = new Options();
+  if (opts.arguments.contains("--run")) {
+    doTest();
+  } else {
+    // Run the test and capture stdout.
+    var pr = Process.runSync(Platform.executable,
+        ["--collect-code",
+         "--code-collection-interval-in-us=100000",
+         "--log-code-drop",
+         "--optimization-counter-threshold=-1",
+         "--package-root=${Platform.packageRoot}",
+         Platform.script,
+         "--run"]);
+
+    // Code drops are logged with --log-code-drop. Look through stdout for the
+    // message that foo's code was dropped.
+    var found = false;
+    pr.stdout.split("\n").forEach((line) {
+      if (line.contains("Detaching code") && line.contains("foo")) {
+        found = true;
+      }
+    });
+    Expect.isTrue(found);
+  }
+}