tail-call-babel.js

'use strict';

var Benchmark = require('benchmark');
var suite = new Benchmark.Suite();

// #1 "naive"
function factorial1(x) {
  if (x <= 0) {
    return 1;
  } else {
    return x * factorial1(x - 1);
  }
}

// #2 tail rec using a default parameter and leaking arguments
function factorial2(n) {
  return facRec2(n);
}
function facRec2(_x2) {
  var _arguments = arguments;
  var _again = true;

  _function: while (_again) {
    var x = _x2;
    _again = false;
    var acc = _arguments.length <= 1 || _arguments[1] === undefined ? 1 : _arguments[1];

    if (x <= 1) {
      return acc;
    } else {
      _arguments = [_x2 = x - 1, x * acc];
      _again = true;
      acc = undefined;
      continue _function;
    }
  }
}

// #2 tail rec using a default parameter and no leaking arguments
function factorial2b(n) {
  return facRec2b(n);
}
function facRec2b(_x5) {
  var $_len = arguments.length;var _arguments = new Array($_len); for(var $_i = 0; $_i < $_len; ++$_i) {_arguments[$_i] = arguments[$_i];}
  var _again = true;

  _functionb: while (_again) {
    var x = _x5;
    _again = false;
    var acc = _arguments.length <= 1 || _arguments[1] === undefined ? 1 : _arguments[1];

    if (x <= 1) {
      return acc;
    } else {
      _arguments = [_x5 = x - 1, x * acc];
      _again = true;
      acc = undefined;
      continue _functionb;
    }
  }
}

// #3 tail rec
function factorial3(n) {
  return facRec3(n, 1);
}
function facRec3(_x3, _x4) {
  var _again2 = true;

  _function2: while (_again2) {
    var x = _x3,
        acc = _x4;
    _again2 = false;

    if (x <= 1) {
      return acc;
    } else {
      _x3 = x - 1;
      _x4 = x * acc;
      _again2 = true;
      continue _function2;
    }
  }
}

// suite.add('#1 no tail call', function() {
//   factorial1(100);
// })
// .add('#2 TCO/default params leaking arguments', function() {
//   factorial2(100);
// })
// .add('#2 TCO/default params no leaking arguments', function() {
//   factorial2b(100);
// })
// .add('#3 TCO/no default params', function() {
//   factorial3(100);
// })
// .on('cycle', function(event) {
//   console.log(String(event.target));
// })
// .on('complete', function() {
//   console.log('Fastest is ' + this.filter('fastest').pluck('name'));
// })
// .run({ 'async': true });

function printStatus(fn) {
  switch(%GetOptimizationStatus(fn)) {
    case 1: console.log(fn.name + ' is optimized'); break;
    case 2: console.log(fn.name + ' is not optimized'); break;
    case 3: console.log(fn.name + ' is always optimized'); break;
    case 4: console.log(fn.name + ' is never optimized'); break;
    case 6: console.log(fn.name + ' is maybe deoptimized'); break;
  }
}

factorial1(100);
factorial1(100);
%OptimizeFunctionOnNextCall(factorial1);
factorial1(100);
printStatus(factorial1);

facRec2(100, 1);
facRec2(100, 1);
%OptimizeFunctionOnNextCall(facRec2);
facRec2(100, 1);
printStatus(facRec2);

facRec2b(100, 1);
facRec2b(100, 1);
%OptimizeFunctionOnNextCall(facRec2b);
facRec2b(100, 1);
printStatus(facRec2b);

facRec3(100, 1);
facRec3(100, 1);
%OptimizeFunctionOnNextCall(facRec3);
facRec3(100, 1);
printStatus(facRec3);