SUZUKI Sosuke f01467d3dc perf(buffer): optimize Buffer.from(array) by using setFromArrayLike directly (#26135) ...

## Summary

Optimizes `Buffer.from(array)` by bypassing `JSC::construct()` overhead
(~30ns) and leveraging JSC's internal array optimizations.

## Changes

- For JSArray inputs, directly use `setFromArrayLike()` which internally
detects array indexing types (Int32Shape/DoubleShape) and uses bulk copy
operations (`copyFromInt32ShapeArray`/`copyFromDoubleShapeArray`)
- Array-like objects and iterables continue to use the existing slow
path
- Added mitata benchmark for measuring performance

## Benchmark Results

| Test | Before | After | Improvement |
|------|--------|-------|-------------|
| Buffer.from(int32[8]) | ~85ns | ~43ns | ~50% faster |
| Buffer.from(int32[64]) | ~207ns | ~120ns | ~42% faster |
| Buffer.from(int32[1024]) | ~1.85μs | ~1.32μs | ~29% faster |
| Buffer.from(double[8]) | ~86ns | ~50ns | ~42% faster |
| Buffer.from(double[64]) | ~212ns | ~151ns | ~29% faster |

Bun is now faster than Node.js for these operations.

## Test

All 449 buffer tests pass.

2026-01-15 12:10:47 -08:00

..

_fixture.txt

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archive.mjs

feat(archive): add TypeScript types, docs, and files() benchmark (#25922)

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array-arguments-slice.mjs

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array-map.mjs

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array-of.js

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array-shift.mjs

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array-sort.mjs

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arraybuffersink.mjs

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assert.mjs

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async-overhead.mjs

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atob.mjs

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blob.mjs

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buffer-base64.mjs

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buffer-concat.mjs

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buffer-create.mjs

js: fix Buffer constructor and Buffer.from (#16731)

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buffer-fill.mjs

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buffer-from-array.mjs

perf(buffer): optimize Buffer.from(array) by using setFromArrayLike directly (#26135)

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buffer-includes.js

node: fix buffer includes+indexof (#16642)

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buffer-read.js

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buffer-to-string.mjs

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buffer.js

node:buffer: fix read (#17299)

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byteLength.mjs

Avoid resolving substrings in bun:sqlite and Buffer.byteLength (#16092)

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callbacks-overhead.mjs

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color.mjs

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compression-streams.mjs

runtime: implement CompressionStream/DecompressionStream (#24757)

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concat.js

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console-log.mjs

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cp-r.mjs

get name if not provided in FormData.append (#4434)

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cp.mjs

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crypto-2190.mjs

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crypto-hasher.mjs

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crypto-randomUUID.mjs

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crypto-stream.mjs

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crypto.mjs

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decode.js

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deep-equals.js

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define-properties.mjs

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dns-prefetch.mjs

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dns.node.mjs

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dns.ts

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encode-into.mjs

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error-capturestack.mjs

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escapeHTML.js

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exists.js

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express-hello.mjs

node:http improvements (#17093)

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fastify.mjs

node:http improvements (#17093)

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ffi-overhead.mjs

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form-data.mjs

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hash.mjs

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headers.mjs

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http-hello.deno.js

Add snippet

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http-hello.js

Add snippet

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http-hello.node.mjs

Fix a couple bugs with node:http (#6924)

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index-of.mjs

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ipc-json-child.mjs

perf(ipc): fix O(n²) JSON scanning for large chunked messages (#25743)

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ipc-json.mjs

perf(ipc): fix O(n²) JSON scanning for large chunked messages (#25743)

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json-parse-stringify.mjs

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json-stringify.js

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jsx-entity-decoding.jsx

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module-exports-putter.cjs

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native-overhead.mjs

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new-incomingmessage.mjs

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node-vm.mjs

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node-zlib-brotli.mjs

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noop.js

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object-entries.mjs

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object-hasown.mjs

[publish images] (+ add Object.hasOwn benchmark)

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object-values.mjs

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path-relative.mjs

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path-resolve.mjs

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pbkdf2.mjs

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peek-promise.mjs

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performance-now-overhead.js

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private.mjs

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process-cwd.mjs

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process-info.mjs

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process.mjs

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promise-race.mjs

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react-dom-render.bun.js

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read-file-chunk.mjs

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realpath.mjs

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redis-simple.mjs

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render.js

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request-method-getter.mjs

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request-response-clone.mjs

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require-builtins.mjs

js: update node:_http_agent (#24275)

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response-arrayBuffer.mjs

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response-json.mjs

perf(Response.json): use JSC's FastStringifier by passing undefined for space (#25717)

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resposne-constructor.mjs

Fix memory leak in response.clone(), further reduce memory usage of Request & Response (#3902)

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return-await.mjs

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rewriter.mjs

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rmdir.mjs

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runner-entrypoint.js

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semver.mjs

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serialize.mjs

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sha512.js

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source-map.js

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string-decoder.mjs

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string-includes.mjs

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string-width.mjs

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strip-ansi.mjs

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structuredClone.mjs

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tcp-echo.bun.ts

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tcp-echo.node.mjs

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text-decoder-stream.mjs

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urlpattern.js

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urlsearchparams.mjs

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zlib.mjs

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