benchmarks: add microbenchmarks for new ES6 features

Adds new microbenchmarks for destructuring, rest params and
default params.

PR-URL: https://github.com/nodejs/node/pull/6222
Reviewed-By: Brian White <mscdex@mscdex.net>

benchmark/es/defaultparams-bench.js

@@ -0,0 +1,58 @@
+'use strict';
+
+const common = require('../common.js');
+const assert = require('assert');
+
+const bench = common.createBenchmark(main, {
+  method: ['withoutdefaults', 'withdefaults'],
+  millions: [100]
+});
+
+function oldStyleDefaults(x, y) {
+  x = x || 1;
+  y = y || 2;
+  assert.strictEqual(x, 1);
+  assert.strictEqual(y, 2);
+}
+
+function defaultParams(x = 1, y = 2) {
+  assert.strictEqual(x, 1);
+  assert.strictEqual(y, 2);
+}
+
+function runOldStyleDefaults(n) {
+
+  common.v8ForceOptimization(oldStyleDefaults);
+
+  var i = 0;
+  bench.start();
+  for (; i < n; i++)
+    oldStyleDefaults();
+  bench.end(n / 1e6);
+}
+
+function runDefaultParams(n) {
+
+  common.v8ForceOptimization(defaultParams);
+
+  var i = 0;
+  bench.start();
+  for (; i < n; i++)
+    defaultParams();
+  bench.end(n / 1e6);
+}
+
+function main(conf) {
+  const n = +conf.millions * 1e6;
+
+  switch (conf.method) {
+    case 'withoutdefaults':
+      runOldStyleDefaults(n);
+      break;
+    case 'withdefaults':
+      runDefaultParams(n);
+      break;
+    default:
+      throw new Error('Unexpected method');
+  }
+}

benchmark/es/destructuring-bench.js

@@ -0,0 +1,50 @@
+'use strict';
+
+const common = require('../common.js');
+const assert = require('assert');
+
+const bench = common.createBenchmark(main, {
+  method: ['swap', 'destructure'],
+  millions: [100]
+});
+
+function runSwapManual(n) {
+  var i = 0, x, y, r;
+  bench.start();
+  for (; i < n; i++) {
+    x = 1, y = 2;
+    r = x;
+    x = y;
+    y = r;
+    assert.strictEqual(x, 2);
+    assert.strictEqual(y, 1);
+  }
+  bench.end(n / 1e6);
+}
+
+function runSwapDestructured(n) {
+  var i = 0, x, y;
+  bench.start();
+  for (; i < n; i++) {
+    x = 1, y = 2;
+    [x, y] = [y, x];
+    assert.strictEqual(x, 2);
+    assert.strictEqual(y, 1);
+  }
+  bench.end(n / 1e6);
+}
+
+function main(conf) {
+  const n = +conf.millions * 1e6;
+
+  switch (conf.method) {
+    case 'swap':
+      runSwapManual(n);
+      break;
+    case 'destructure':
+      runSwapDestructured(n);
+      break;
+    default:
+      throw new Error('Unexpected method');
+  }
+}

benchmark/es/restparams-bench.js

@@ -0,0 +1,85 @@
+'use strict';
+
+const common = require('../common.js');
+const assert = require('assert');
+
+const bench = common.createBenchmark(main, {
+  method: ['copy', 'rest', 'arguments'],
+  millions: [100]
+});
+
+function copyArguments() {
+  var len = arguments.length;
+  var args = new Array(len);
+  for (var i = 0; i < len; i++)
+    args[i] = arguments[i];
+  assert.strictEqual(args[0], 1);
+  assert.strictEqual(args[1], 2);
+  assert.strictEqual(args[2], 'a');
+  assert.strictEqual(args[3], 'b');
+}
+
+function restArguments(...args) {
+  assert.strictEqual(args[0], 1);
+  assert.strictEqual(args[1], 2);
+  assert.strictEqual(args[2], 'a');
+  assert.strictEqual(args[3], 'b');
+}
+
+function useArguments() {
+  assert.strictEqual(arguments[0], 1);
+  assert.strictEqual(arguments[1], 2);
+  assert.strictEqual(arguments[2], 'a');
+  assert.strictEqual(arguments[3], 'b');
+}
+
+function runCopyArguments(n) {
+
+  common.v8ForceOptimization(copyArguments, 1, 2, 'a', 'b');
+
+  var i = 0;
+  bench.start();
+  for (; i < n; i++)
+    copyArguments(1, 2, 'a', 'b');
+  bench.end(n / 1e6);
+}
+
+function runRestArguments(n) {
+
+  common.v8ForceOptimization(restArguments, 1, 2, 'a', 'b');
+
+  var i = 0;
+  bench.start();
+  for (; i < n; i++)
+    restArguments(1, 2, 'a', 'b');
+  bench.end(n / 1e6);
+}
+
+function runUseArguments(n) {
+
+  common.v8ForceOptimization(useArguments, 1, 2, 'a', 'b');
+
+  var i = 0;
+  bench.start();
+  for (; i < n; i++)
+    useArguments(1, 2, 'a', 'b');
+  bench.end(n / 1e6);
+}
+
+function main(conf) {
+  const n = +conf.millions * 1e6;
+
+  switch (conf.method) {
+    case 'copy':
+      runCopyArguments(n);
+      break;
+    case 'rest':
+      runRestArguments(n);
+      break;
+    case 'arguments':
+      runUseArguments(n);
+      break;
+    default:
+      throw new Error('Unexpected method');
+  }
+}