buffer: use simdutf for two-byte utf8 byteLength

[mertcanaltin]

I changed two-byte (UTF-16) string path, we are now switching from V8 Utf8LengthV2 to simdutf,

note: simdutf is only enabled for two-byte strings containing 512 code units or more

benchmark results:

➜ node git:(mert/buffer-bytelength-utf8-simdutf) ✗ node-benchmark-compare /tmp/nvb/result2.csv
confidence improvement accuracy (*) (**) (***)
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='four_bytes' 0.56 % ±1.66% ±2.21% ±2.87%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='latin1' 0.45 % ±1.50% ±2.00% ±2.61%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='one_byte' 1.49 % ±1.85% ±2.46% ±3.21%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='three_bytes' 0.02 % ±1.40% ±1.87% ±2.45%
buffers/buffer-bytelength-string.js n=4000000 repeat=1 encoding='utf8' type='two_bytes' 0.96 % ±1.37% ±1.82% ±2.37%
buffers/buffer-bytelength-string.js n=4000000 repeat=16 encoding='utf8' type='four_bytes' *** 28.95 % ±1.10% ±1.47% ±1.92%
buffers/buffer-bytelength-string.js n=4000000 repeat=16 encoding='utf8' type='latin1' * -0.74 % ±0.59% ±0.79% ±1.03%
buffers/buffer-bytelength-string.js n=4000000 repeat=16 encoding='utf8' type='one_byte' 0.14 % ±1.41% ±1.88% ±2.45%
buffers/buffer-bytelength-string.js n=4000000 repeat=16 encoding='utf8' type='three_bytes' ** 2.25 % ±1.66% ±2.21% ±2.88%
buffers/buffer-bytelength-string.js n=4000000 repeat=16 encoding='utf8' type='two_bytes' 1.38 % ±1.73% ±2.30% ±2.99%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='four_bytes' * -1.44 % ±1.35% ±1.80% ±2.34%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='latin1' 0.09 % ±1.29% ±1.72% ±2.24%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='one_byte' -0.77 % ±1.77% ±2.36% ±3.07%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='three_bytes' 0.86 % ±1.65% ±2.20% ±2.86%
buffers/buffer-bytelength-string.js n=4000000 repeat=2 encoding='utf8' type='two_bytes' * -1.69 % ±1.61% ±2.14% ±2.78%
buffers/buffer-bytelength-string.js n=4000000 repeat=256 encoding='utf8' type='four_bytes' *** 36.25 % ±1.23% ±1.65% ±2.19%
buffers/buffer-bytelength-string.js n=4000000 repeat=256 encoding='utf8' type='latin1' -0.20 % ±0.24% ±0.32% ±0.41%
buffers/buffer-bytelength-string.js n=4000000 repeat=256 encoding='utf8' type='one_byte' * -0.72 % ±0.63% ±0.84% ±1.10%
buffers/buffer-bytelength-string.js n=4000000 repeat=256 encoding='utf8' type='three_bytes' *** 67.59 % ±1.42% ±1.91% ±2.52%
buffers/buffer-bytelength-string.js n=4000000 repeat=256 encoding='utf8' type='two_bytes' *** 67.62 % ±1.23% ±1.65% ±2.18%
Be aware that when doing many comparisons the risk of a false-positive result increases.
In this case, there are 20 comparisons, you can thus expect the following amount of false-positive results:
1.00 false positives, when considering a 5% risk acceptance (*, **, ***),
0.20 false positives, when considering a 1% risk acceptance (**, ***),
0.02 false positives, when considering a 0.1% risk acceptance (***)
➜ node git:(mert/buffer-bytelength-utf8-simdutf) ✗

[codecov]

Codecov Report

❌ Patch coverage is 52.38095% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.30%. Comparing base (4d21e86) to head (f382a03).
⚠️ Report is 65 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_buffer.cc	52.38%	8 Missing and 2 partials ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #63639 +/- ##
==========================================
+ Coverage 90.29% 90.30% +0.01% 
==========================================
Files 730 730 Lines 234773 234821 +48 Branches 43953 43959 +6 ==========================================
+ Hits 211996 212066 +70 + Misses 14495 14484 -11 + Partials 8282 8271 -11 

Files with missing lines	Coverage Δ
src/node_buffer.cc	68.10% <52.38%> (-0.28%)	⬇️

... and 39 files with indirect coverage changes

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[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73888/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73895/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73910/

[addaleax]

Landed in 4035c57