asm.js sample

fibonacci.js

function fast_fib_module(stdlib, foreign, heap) {
  "use asm";

  function fib(n) {
    n = n|0;
    
    // nはint(符号の有無が不明の状態)
    // 3はfixnum(0~2^31)
    // 比較するためにnをシフト演算でunsignedに変換する
    if (n >>> 0 < 3) {
      return 1|0;
    }
    
    // fibの引数の型はintなのでintのサブセットであるsigned intで渡す
    return (fib((n-1)|0) + fib((n-2)|0))|0;
  }

  return {
    fib:fib
  };
}
fast_fib = fast_fib_module(window).fib;

function slow_fib(n) {
  if (n < 3) {
    return 1;
  }
  return slow_fib(n-1) + slow_fib(n-2);
}

function fast_check(n) {
  console.time("ASM:fib(" + n + ")");
  console.log(fast_fib(n));
  console.timeEnd("ASM:fib(" + n + ")");
}

function slow_check(n) {
  console.time("NORMAL:fib(" + n + ")");
  console.log(slow_fib(n));
  console.timeEnd("NORMAL:fib(" + n + ")");
}

result

[01:40:15.035] fast_check(35)
[01:40:15.037] undefined
[01:40:15.037] ASM:fib(35): タイマー開始
[01:40:15.076] 9227465
[01:40:15.076] ASM:fib(35): 39ms
--
[01:40:21.539] slow_check(35)
[01:40:21.541] undefined
[01:40:21.541] NORMAL:fib(35): タイマー開始
[01:40:26.163] 9227465
[01:40:26.163] NORMAL:fib(35): 4622ms

How do I use this in my browser? Do I need more than your fibonacci.js to see the effect of ASM? Do I have to use a special version of Firefox?

When I try this i Firefox (27.0), I get this re. line 15: "TypeError: asm.js type error: non-expression-statement call must be coerced"
Does that explain why slow_check is faster than fast_check?