[js-perf-test] add microbenchmarks for Object.values(), Object.entries()

test/js-perf-test/Object/entries.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+new BenchmarkSuite('Entries', [1000], [
+  new Benchmark('Basic', false, false, 0, Basic, BasicSetup, BasicTearDown)
+]);
+
+var object;
+var expected;
+var result;
+var symbol1;
+
+function Basic() {
+  result = Object.entries(object);
+}
+
+
+function BasicSetup() {
+  result = undefined;
+  symbol1 = Symbol('test');
+  object = { a: 10 };
+  object[26.0] = 'third';
+  object.b = 72;
+  object[symbol1] = 'TEST';
+  Object.defineProperty(object, 'not-enumerable', {
+      enumerable: false, value: 'nope', writable: true, configurable: true });
+}
+
+
+function BasicTearDown() {
+  result = result.map(entry => `[${[String(entry[0]), String(entry[1])]}]`);
+  return result.length === 3 &&
+         result.join(', ') === '[a, 10], [26.0, third], [b, 72]';
+}
+
+// ----------------------------------------------------------------------------
+
+new BenchmarkSuite('EntriesMegamorphic', [1000], [
+  new Benchmark('BasicMegamorphic', false, false, 0, BasicMegamorphic,
+                BasicMegamorphicSetup, BasicMegamorphicTearDown)
+]);
+
+function BasicMegamorphic() {
+  for (var i = 0; i < object.length; ++i) {
+    result[i] = Object.entries(object[i]);
+  }
+}
+
+
+function BasicMegamorphicSetup() {
+  // Create 1k objects with different maps.
+  object = [];
+  expected = [];
+  result = [];
+  for (var i=0; i<1000; i++) {
+    var obj = {};
+    var exp = [];
+    for (var j=0; j<10; j++) {
+      obj['key-'+i+'-'+j] = 'property-'+i+'-'+j;
+      exp[j] = ['key-'+i+'-'+j, 'property-'+i+'-'+j];
+    }
+    object[i] = obj;
+    expected[i] = exp;
+  }
+}
+
+
+function BasicMegamorphicTearDown() {
+  if (JSON.stringify(expected) !== JSON.stringify(result)) {

[Camillo Bruni, 2016/03/07 08:21:54]

Right, this seems like a good solution to prevent total optimization.

+    throw new Error("FAILURE");
+  }
+  object = result = expected = undefined;
+  return true;
+}