Buffer.byteLength Performance Regression from v18.x to v22.x

[kylo5aby]

For Buffer.byteLength(string[, encoding]), when set encoding is buffer:

buffers/buffer-bytelength.js n=4000000 len=16 encoding='buffer'                                                                                   ***    -36.69 %       ±1.78%  ±2.38%  ±3.09%
buffers/buffer-bytelength.js n=4000000 len=2 encoding='buffer'                                                                                    ***    -35.95 %       ±3.34%  ±4.48%  ±5.91%
buffers/buffer-bytelength.js n=4000000 len=256 encoding='buffer'                                                                                  ***    -35.46 %       ±5.18%  ±6.95%  ±9.17%

During my investigation, I found that the performance regression might be due to ArrayBufferView.byteLength.

for the implementation of Buffer.byteLength in lib:

function byteLength(string, encoding) {
  if (typeof string !== 'string') {
    if (isArrayBufferView(string) || isAnyArrayBuffer(string)) {
      return string.byteLength;
    }
    // ...
  }
}

when string.byteLength is not called in either v18.x or v22.x(for example, change to return 0), the regression nearly disappears:

                                                       confidence improvement accuracy (*)   (**)  (***)
buffers/buffer-bytelength-buffer.js n=60000000 len=16         ***     -3.16 %       ±1.25% ±1.66% ±2.16%
buffers/buffer-bytelength-buffer.js n=60000000 len=2                  -1.39 %       ±2.15% ±2.86% ±3.74%
buffers/buffer-bytelength-buffer.js n=60000000 len=256         **     -2.16 %       ±1.28% ±1.72% ±2.25%

Based on the findings, it appears that the handling of ArrayBufferView.byteLength might be the cause of the performance regression observed.