deps: V8: cherry-pick Highway string performance patches#61825
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rmagrin wants to merge 2 commits intonodejs:mainfrom
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deps: V8: cherry-pick Highway string performance patches#61825rmagrin wants to merge 2 commits intonodejs:mainfrom
rmagrin wants to merge 2 commits intonodejs:mainfrom
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Original commit message:
Reland "use highway to check and copy leading ascii"
This is a reland of commit a3e84e5f01540cec142f4d4f41f1921373c220e5
Original change's description:
> use highway to check and copy leading ascii
>
> Change-Id: I065532aeeee95273821aa1f25b5ffc5c5c23cbf1
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7172479
> Reviewed-by: Patrick Thier <pthier@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Dan Carney <dcarney@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#103820}
Change-Id: I43b4ad18817eb52b701e112d2d0a5f685374ae1f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7184338
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Commit-Queue: Dan Carney <dcarney@chromium.org>
Cr-Commit-Position: refs/heads/main@{#103865}
Refs: v8/v8@67507b2
Original commit message:
[api][strings] Optimize ContainsOnlyOneByte with SIMD
Add Highway-based SIMD implementation for checking if strings contain
only one-byte (Latin-1) characters. Highway provides portable SIMD
abstraction across different architectures with automatic target
selection at runtime.
The SIMD implementation processes 8 uint16_t values (128 bits) at
once,checking if any character has the high byte set. This provides
significant speedup over the previous implementation which processed 2-4
values per iteration and only checked every 16 iterations.
The optimization applies to both String::ContainsOnlyOneByte() in the
public API and the internal IsOnly8Bit() helper used during string
hashing. This improves performance for string validation, encoding
decisions, and UTF-8/UTF-16 conversion operations.
Additionally, it resolves a TODO by leszeks.
Change-Id: I41f519339fb96f3bf3f4fa30283f84ccbb5115d0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7159233
Reviewed-by: Erik Corry <erikcorry@chromium.org>
Commit-Queue: Erik Corry <erikcorry@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#104120}
Refs: v8/v8@c135d5e
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Summary
Cherry-picks two V8 patches that improve string performance using Highway SIMD:
67507b2a88f4— Reland "use highway to check and copy leading ascii" (Dan Carney)Replaces
IsAsciiOneByteString+memcpywith HighwayWriteLeadingAsciiinUtf8::Encode, providing a faster ASCII fast path forWriteUtf8V2.CL: https://chromium-review.googlesource.com/c/v8/v8/+/7184338
c135d5e81f82— OptimizeContainsOnlyOneBytewith SIMD (Yagiz Nizipli)Adds Highway-based SIMD implementation for checking if strings contain only one-byte (Latin-1) characters, replacing the scalar loop in both
String::ContainsOnlyOneByte()and the internalIsOnly8Bit()helper.CL: https://chromium-review.googlesource.com/c/v8/v8/+/7159233
These patches address the remaining ~30-40% performance gap in
WriteUtf8V2vs v22 after #61712 landed the initialsimdutf+memcpyfast path.Refs: #60719
Test plan