For Micro-benchmarks for 'with'

test/js-perf-test/Scope/with.js

+// Copyright 2015 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( 'With', [1000], [
+  new Benchmark('AccessOnSameLevel', false, false, 0,
+                AccessOnSameLevel, AccessOnSameLevelSetup,
+                AccessOnSameLevelTearDown),
+  new Benchmark('SetOnSameLevel', false, false, 0,
+                SetOnSameLevel, SetOnSameLevelSetup,
+                SetOnSameLevelTearDown),
+  new Benchmark('AccessOverPrototypeChain', false, false, 0,
+                AccessOverPrototypeChainSetup, AccessOverPrototypeChainSetup,
+                AccessOverPrototypeChainTearDown),
+  new Benchmark('CompetingScope', false, false, 0,
+                CompetingScope, CompetingScopeSetup, CompetingScopeTearDown)
+]);
+
+var objectUnderTest;
+var objectUnderTestExtended;
+var resultStore;
+var VALUE_OF_PROPERTY = 'Simply a string';
+var SOME_OTHER_VALUE = 'Another value';
+
+// ----------------------------------------------------------------------------
+
+function AccessOnSameLevelSetup() {
+  objectUnderTest = {first: VALUE_OF_PROPERTY};
+}
+
+function AccessOnSameLevel() {
+  with (objectUnderTest) {
+    resultStore = first;
+  }
+}
+
+function AccessOnSameLevelTearDown() {
+  return objectUnderTest.first === resultStore;
+}
+
+// ----------------------------------------------------------------------------
+
+function AccessOverPrototypeChainSetup() {
+  objectUnderTest = {first: VALUE_OF_PROPERTY};
+  objectUnderTestExtended = Object.create(objectUnderTest);
+  objectUnderTestExtended.second = 'Another string';
+}
+
+function AccessOverPrototypeChain() {
+  with (objectUnderTestExtended) {
+    resultStore = first;
+  }
+}
+
+function AccessOverPrototypeChainTearDown() {
+  return objectUnderTest.first === resultStore;
+}
+
+// ----------------------------------------------------------------------------
+
+function CompetingScopeSetup() {
+  objectUnderTest = {first: VALUE_OF_PROPERTY};
+}
+
+function CompetingScope() {
+  var first = 'Not correct';
+  with (objectUnderTest) {
+    resultStore = first;
+  }
+}
+
+function CompetingScopeTearDown() {
+  return objectUnderTest.first === resultStore;
+}
+
+// ----------------------------------------------------------------------------
+
+function SetOnSameLevelSetup() {
+  objectUnderTest = {first: VALUE_OF_PROPERTY};
+}
+
+function SetOnSameLevel() {
+  with (objectUnderTest) {
+    first = SOME_OTHER_VALUE;
+  }
+}
+
+function SetOnSameLevelTearDown() {
+  return objectUnderTest.first === SOME_OTHER_VALUE;
+}