DmitrySoshnikov

Generated code optimizations and tricks

I've been playing with generated (native) code in order to test how compilers (specific or in general) translate a = a + 1 and a++, and found some other interesting optimizations. I used gcc compiler for this simple program:

int main() {
  int a = 0;
  a = a + 1;

  int b = 0;

DmitrySoshnikov

/**
 * by Dmitry A. Soshnikov
 */

Object.defineProperty(Object, "essence", {
  value: function objectEssence(value) {
    var essence = {kind: Object.prototype.toString.call(value).slice(8, -1)};
    // use Object(value) just for shortness, it's less effective
    // than typeof value == "object" && value !== null || typeof value == "function"
    essence[value === Object(value) ? "object" : "primitive"] = true;

DmitrySoshnikov

/**
 * Abstract representation of ES3
 * or ES5-non-strict sharing of
 * passed formal parameters and
 * corresponding indexes of the
 * arguments object
 *
 * Implemented in ES5, non-strict
 * tested in BESEN rev. 109
 * 

DmitrySoshnikov

/**
 * Delegation based mixins for JavaScript.
 *
 * Non-specific extensions are used:
 *    __proto__
 *    __noSuchMethod__
 *
 * Tested in SpiderMonkey.
 *
 * Opened issues:

DmitrySoshnikov

// Latest Firefox (including nightly):

// INCORRECT with FDs

(function () {
  
  // a function declaration
  // does not replace arguments object
  function arguments() {}
  alert(arguments); // "[object Object]", should be function

DmitrySoshnikov

// loop-code-gen.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"


int _tmain(int argc, _TCHAR* argv[])
{
    int i = 0, n = 1;

DmitrySoshnikov

/**
 * This library extends standard "Object.create" method
 * with ability to create object with specified class.
 *
 * Also it defines concept of a meta-constructor which
 * creates other construcotrs, which in turn create
 * object with specified class.
 *
 * Currently, non-standard __proto__ extension
 * is used to inject the needed prototype for arrays.

DmitrySoshnikov

int main()
{
    int i = 0, n = 1;

    while (i++ < n) if (i == 1) break;
    while (i++ < n && i != 1);

    return 0;
}

DmitrySoshnikov

/**
 * This library defines a new style ES objects
 * which support delegation based mixins. A mixin
 * chain is stored in the internal [[Mixin]] property.
 *
 * Used features: Harmony (ES6) proxies.
 *
 * Tested in FF4 beta.
 *
 * @author Dmitry A. Soshnikov <dmitry.soshnikov@gmail.com>

DmitrySoshnikov

/**
 * Console object for BESEN
 * @author Dmitry A. Soshnikov <dmitry.soshnikov@gmail.com>
 */
(function initConsole(global) {

  // helpers

  var getClass = Object.prototype.toString;
  var timeMap = {};