manually inlining validator functions improves performance

[Uzlopak]

Lets take the isAbsolute function of posix in the path module.

  /**
   * @param {string} path
   * @returns {boolean}
   */
  isAbsolute(path) {
    validateString(path, 'path');
    return path.length > 0 &&
           StringPrototypeCharCodeAt(path, 0) === CHAR_FORWARD_SLASH;
  },

Benchmark it:

./node benchmark/path/isAbsolute-posix.js 
path/isAbsolute-posix.js n=100000 path="": 26,199,553.088023424
path/isAbsolute-posix.js n=100000 path=".": 19,512,560.625525866
path/isAbsolute-posix.js n=100000 path="/foo/bar": 15,003,530.33068681
path/isAbsolute-posix.js n=100000 path="/baz/..": 20,841,496.252698973
path/isAbsolute-posix.js n=100000 path="bar/baz": 25,044,717.342815597

inline validateString

  /**
   * @param {string} path
   * @returns {boolean}
   */
  isAbsolute(path) {
    if (typeof path !== 'string')
      throw new ERR_INVALID_ARG_TYPE('path', 'string', path);
    return path.length > 0 &&
           StringPrototypeCharCodeAt(path, 0) === CHAR_FORWARD_SLASH;
  },

./node benchmark/path/isAbsolute-posix.js 
path/isAbsolute-posix.js n=100000 path="": 49,143,043.605605446
path/isAbsolute-posix.js n=100000 path=".": 36,665,695.025748484
path/isAbsolute-posix.js n=100000 path="/foo/bar": 20,950,367.322790273
path/isAbsolute-posix.js n=100000 path="/baz/..": 22,806,405.772027623
path/isAbsolute-posix.js n=100000 path="bar/baz": 41,722,470.470921524

Annoying...

[ronag]

can you share the benchmark?

[targos]

This is not surprising, the inline version doesn't need hideStackFrames.
The only other solution I see is using a macro system (that was removed some years ago).

[aduh95]

Maybe we could make the "stack hiding" feature opt-in/opt-out. I'm not sure what's the use-case behind that, but I think many folks would gladly take the extra stack lines as a tradeoff for the increase performance.

[lemire]

What is going here? V8 ought to be able to inline the function during the JIT compilation, no?

function validateString(value, name) {
  if (typeof value !== 'string') {
    throw new ERR_INVALID_ARG_TYPE(name, 'String', value);
  }
}

Why won't it?

[Uzlopak]

I dont know but I think this is because you pass by val and not by ref.