Benchmark: Math.imul vs. polyfills

Script Preparation code:

var x = 0x12345678;
var y;

Math.imula = function(opA, opB) {
  opB |= 0; // ensure that opB is an integer. opA will automatically be coerced.
  // floating points give us 53 bits of precision to work with plus 1 sign bit
  // automatically handled for our convienence:
  // 1. 0x003fffff /*opA & 0x000fffff*/ * 0x7fffffff /*opB*/ = 0x1fffff7fc00001
  //    0x1fffff7fc00001 < Number.MAX_SAFE_INTEGER /*0x1fffffffffffff*/
  var result = (opA & 0x003fffff) * opB;
  // 2. We can remove an integer coersion from the statement above because:
  //    0x1fffff7fc00001 + 0xffc00000 = 0x1fffffff800001
  //    0x1fffffff800001 < Number.MAX_SAFE_INTEGER /*0x1fffffffffffff*/
  if (opA & 0xffc00000 /*!== 0*/) result += (opA & 0xffc00000) * opB |0;
  return result |0;
};

Math.imulb = function(a, b) {
  var aHi = (a >>> 16) & 0xffff;
  var aLo = a & 0xffff;
  var bHi = (b >>> 16) & 0xffff;
  var bLo = b & 0xffff;
  // the shift by 0 fixes the sign on the high part
  // the final |0 converts the unsigned value into a signed value
  return ((aLo * bLo) + (((aHi * bLo + aLo * bHi) << 16) >>> 0) | 0);
};

Tests:

Math.imul
for (var i = 0; i < 10000; ++i) { y = Math.imul(x, i); }
Polyfill a
for (var i = 0; i < 10000; ++i) { y = Math.imula(x, i); }
Polyfill b
for (var i = 0; i < 10000; ++i) { y = Math.imulb(x, i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Math.imul
Polyfill a
Polyfill b

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmarking test case on the MeasureThat.net website. The goal is to compare the performance of three different implementations of the `Math.imul` function: the original implementation, and two polyfills (polyfill "a" and polyfill "b").

**Original Implementation**

The original implementation is not provided in the JSON data, but it's likely the same as the one used in modern JavaScript engines. The implementation uses a combination of bitwise operations to perform the multiplication.

```javascript
Math.imul = function(opA, opB) {
  // ...
}
```

The pros of this implementation are:

* It's highly optimized for performance and uses low-level bitwise operations.
* It's likely to be well-optimized by modern JavaScript engines.

However, it may have some cons:

* It might not work correctly for all edge cases or invalid inputs.
* It may rely on internal engine implementation details that could change in the future.

**Polyfill "a"**

The polyfill "a" is implemented as follows:

```javascript
Math.imul = function(opA, opB) {
  // ...
}
```

This implementation seems to be a direct copy of the original implementation, without any significant changes. The pros are:

* It's likely to work correctly for all edge cases and invalid inputs.
* It provides a fallback for browsers that don't support the `Math.imul` function.

However, it might have some cons:

* It may not be optimized for performance, as it doesn't use low-level bitwise operations like the original implementation.
* It relies on the internal engine implementation details of MeasureThat.net, which could change in the future.

**Polyfill "b"**

The polyfill "b" is implemented as follows:

```javascript
Math.imulb = function(a, b) {
  // ...
}
```

This implementation seems to use a different approach to perform the multiplication. The pros are:

* It might be optimized for performance, using low-level bitwise operations.
* It provides an alternative implementation that can work in different browsers.

However, it might have some cons:

* It's not directly comparable to the original implementation, as it uses a different function name and signature.
* It relies on the internal engine implementation details of MeasureThat.net, which could change in the future.

**Other Considerations**

In addition to the above implementations, there may be other polyfills or alternatives available for `Math.imul`. Some examples include:

* Using a library like Polyfill.io or js-polyfill that provides a set of polyfills for various JavaScript functions.
* Implementing a custom polyfill using a different approach, such as using a library like Bitwise.js.

**Device Platform and Browser**

The benchmark results show the performance of each implementation on a desktop browser (Chrome 128) with Windows. The pros of this are:

* It provides a clear and consistent environment for testing the implementations.
* It allows for accurate comparisons between the different implementations.

However, it might have some cons:

* The results may not be representative of other devices or browsers.
* The performance differences between the implementations may be exaggerated by the specific browser and device platform used.

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Windows

View result in a separate tab

Test name	Executions per second
Math.imul	554.3 Ops/sec
Polyfill a	544.0 Ops/sec
Polyfill b	554.1 Ops/sec

Related benchmarks:

Math.imul vs. polyfills (version: 0)

Comparing performance of: Math.imul vs Polyfill a vs Polyfill b

Created: 4 years ago by: Guest

Jump to the latest result

Math.imul

Polyfill a

Polyfill b

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):