perf(rolldown): minor performance optimization by Brooooooklyn · Pull Request #6271 · rolldown/rolldown

Brooooooklyn · 2025-09-18T13:46:30Z

pre-allocate memory
use simdutf8 rather than String utf8 check
avoid double utf8 checks in text_to_string_literal

Brooooooklyn · 2025-09-18T13:46:49Z

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Pull Request Overview

This PR implements several minor performance optimizations across the rolldown codebase, focusing on memory pre-allocation and UTF-8 validation improvements.

Replaces standard library UTF-8 validation with simdutf8 for better performance
Pre-allocates memory for String operations to reduce reallocations
Eliminates redundant UTF-8 validation checks by using unsafe operations where safety is guaranteed

Reviewed Changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
crates/rolldown_utils/src/percent_encoding.rs	Switches from std::str to simdutf8 for UTF-8 validation
crates/rolldown_utils/src/mime.rs	Adds inline attribute to is_valid_utf8 function
crates/rolldown_utils/src/ecmascript.rs	Pre-allocates String capacity in legitimize_identifier_name
crates/rolldown_utils/src/base64.rs	Adds inline attributes to base64 encoding functions
crates/rolldown_plugin_data_uri/src/lib.rs	Uses unsafe UTF-8 conversion after base64 decoding
crates/rolldown_common/src/types/str_or_bytes.rs	Optimizes UTF-8 validation and conversion
crates/rolldown_common/Cargo.toml	Adds simdutf8 dependency
crates/rolldown/src/utils/text_to_esm.rs	Pre-allocates memory and avoids double UTF-8 validation in JSON serialization

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crates/rolldown_plugin_data_uri/src/lib.rs

crates/rolldown/src/utils/text_to_esm.rs

github-actions · 2025-09-18T14:26:09Z

Benchmarks Rust

target: main(2c840d5)
pr: 09-18-perf_rolldown_minor_performance_optimization(230eae6)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00    153.4±2.77ms        ? ?/sec    1.04    160.1±2.51ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.00    165.9±3.28ms        ? ?/sec    1.03    171.5±3.35ms        ? ?/sec
bundle/bundle@rome_ts                                        1.00    239.7±4.60ms        ? ?/sec    1.02    244.3±5.34ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    268.0±3.43ms        ? ?/sec    1.05    282.3±5.05ms        ? ?/sec
bundle/bundle@threejs                                        1.00     85.6±2.35ms        ? ?/sec    1.02     87.0±1.51ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     97.9±1.47ms        ? ?/sec    1.01     99.1±1.65ms        ? ?/sec
bundle/bundle@threejs10x                                     1.00    958.5±9.10ms        ? ?/sec    1.03   982.9±12.41ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00   1058.4±8.62ms        ? ?/sec    1.01   1066.0±9.79ms        ? ?/sec
scan/scan@rome_ts                                            1.00    216.7±5.24ms        ? ?/sec    1.00    215.8±4.96ms        ? ?/sec
scan/scan@threejs                                            1.00     77.0±0.98ms        ? ?/sec    1.00     77.1±1.63ms        ? ?/sec
scan/scan@threejs10x                                         1.00   849.0±23.70ms        ? ?/sec    1.00   848.5±22.77ms        ? ?/sec

crates/rolldown_plugin_data_uri/src/lib.rs

Brooooooklyn · 2025-09-18T14:49:19Z

cursor review

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✅ Bugbot reviewed your changes and found no bugs!

IWANABETHATGUY · 2025-09-18T17:12:12Z

Merge activity

Sep 18, 5:12 PM UTC: The merge label 'graphite: merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Sep 18, 5:12 PM UTC: IWANABETHATGUY added this pull request to the Graphite merge queue.
Sep 18, 5:33 PM UTC: Merged by the Graphite merge queue.

- pre-allocate memory - use simdutf8 rather than String utf8 check - avoid double utf8 checks in text_to_string_literal

netlify · 2025-09-18T17:21:56Z

✅ Deploy Preview for rolldown-rs canceled.

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🔨 Latest commit	`230eae6`
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@Boshen

## [1.0.0-beta.39] - 2025-09-22 ⚡ MacOS Performance Boost - 10%-30% faster bundling - Up to 45% in extreme cases ### 🚀 Features - rolldown: oxc v0.90.0 + other oxc crate updates (#6274) by @Boshen - support ignoring `/* @vite-ignore */` comment for dynamic imports (#6264) by @IWANABETHATGUY - dev: merge mergeable queued tasks into one (#6253) by @hyf0 - dev: ignore self imports when computing update for invalidate (#6252) by @sapphi-red - support `#__NO_SIDE_EFFECTS__` annotation for export default function declaration (#6239) by @IWANABETHATGUY - rolldown_plugin_dynamic_import_vars: respect `@vite-ignore` comment (#6240) by @shulaoda - rolldown_plugin_import_glob: support `exhaustive` option (#6236) by @shulaoda - cross chunk /* @__NO_SIDE_EFFECTS__ */ support (#6207) by @IWANABETHATGUY - rolldown_plugin_react_refresh_wrapper: make the plugin callable (#6229) by @sapphi-red ### 🐛 Bug Fixes - handle optional chaining in scope hoisting member expression rewriting (#6278) by @shulaoda - release: Fix semver commit release format to use plus instead of dash (#6273) by @Copilot - dev: `ensure_latest_build_output` should work correctly when `eagerBuild: false` (#6262) by @hyf0 - browser: does not work in stackblitz (#6257) by @shulaoda - only inline constants that are not reassigned (#6247) by @IWANABETHATGUY - handle lexical declarations in root scope (#6230) by @IWANABETHATGUY ### 🚜 Refactor - move oxc runtime helper generation from `build.rs` to task generator (#6284) by @shulaoda - remove unused `SpanExt` (#6266) by @IWANABETHATGUY - remove `@rolldown-ignore` ignore comment support (#6265) by @IWANABETHATGUY - enhance CommonJsAstType to track property names (#6250) by @IWANABETHATGUY - simplify usage for `Address::from` (#6245) by @IWANABETHATGUY - remove `stmt_info_idx` in StmtInfo (#6244) by @IWANABETHATGUY - extract `CrossModuleOptimizationRunnerContext` in cross_module_optimization (#6243) by @IWANABETHATGUY - dev: task-queue based deisgn (#6233) by @hyf0 - extract immutable context from AstScanner (#6238) by @IWANABETHATGUY - dev: rename `WatcherEventService` to `BuildDriverService` (#6232) by @hyf0 - move FlatOptions to rolldown_common (#6235) by @IWANABETHATGUY - extract mutable state from ScopeHoistingFinalizerContext (#6234) by @IWANABETHATGUY - wait `this.load` using futures instead of callbacks (#6222) by @sapphi-red - rolldown_plugin_transform: remove unused `runtime_resolve_base` option (#6226) by @sapphi-red ### 📚 Documentation - add "edit this page on GitHub" button (#6241) by @siaeyy ### ⚡ Performance - rolldown: minor performance optimization (#6271) by @Brooooooklyn - rolldown: take advantage of tokio blocking threads (#6270) by @Brooooooklyn ### 🧪 Testing - dev: add rebuild after HMR case (#6260) by @sapphi-red - dev: support full reload in tests (#6259) by @sapphi-red - dev: extract waitFor from waitForPathExists (#6261) by @sapphi-red - add class like cases for empty function optimizations (#6248) by @sapphi-red ### ⚙️ Miscellaneous Tasks - deps: update github-actions (#6298) by @renovate[bot] - deps: update dependency dprint/dprint-plugin-typescript to v0.95.11 (#6296) by @renovate[bot] - deps: update dependency dprint/dprint-plugin-markdown to v0.19.0 (#6295) by @renovate[bot] - deps: update dependency g-plane/pretty_yaml to v0.5.1 (#6294) by @renovate[bot] - use a forked version of openharmony-rs/setup-ohos-sdk (#6290) by @Boshen - deps: update dependency tsdown to v0.15.4 (#6286) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.16.7 (#6285) by @renovate[bot] - rust: continue to make `cargo publish --workspace` work (#6281) by @Boshen - deps: update dependency tsdown to v0.15.3 (#6280) by @renovate[bot] - rust: fixes for `cargo publish --dry-run --workspace` (#6279) by @Boshen - deps: update dependency rust to v1.90.0 (#6277) by @renovate[bot] - deps: update dependency rolldown-plugin-dts to v0.16.6 (#6276) by @renovate[bot] - adding tracing for all sub stage in LinkStage:link (#6268) by @IWANABETHATGUY - deps: update oxc-project/setup-node action to v1.0.4 (#6258) by @renovate[bot] - deps: update github-actions (#6249) by @renovate[bot] - deps: update dependency tsdown to v0.15.2 (#6242) by @renovate[bot] - dev: output error when the initial bundle failed (#6228) by @sapphi-red ### ❤️ New Contributors * @siaeyy made their first contribution in [#6241](#6241)

github-actions bot assigned Brooooooklyn Sep 18, 2025

This was referenced Sep 18, 2025

perf(rolldown): take advantage of tokio blocking threads #6270

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perf(rolldown): fine-tuning the tokio scheduler #6272

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Brooooooklyn force-pushed the 09-18-perf_rolldown_minor_performance_optimization branch 3 times, most recently from dbc9162 to 1b110f4 Compare September 18, 2025 13:58

Brooooooklyn requested review from IWANABETHATGUY and Copilot September 18, 2025 14:00

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crates/rolldown_plugin_data_uri/src/lib.rs Outdated Show resolved Hide resolved

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Brooooooklyn force-pushed the 09-18-perf_rolldown_minor_performance_optimization branch from 1b110f4 to 7da7c8f Compare September 18, 2025 14:03

Brooooooklyn force-pushed the 09-18-perf_rolldown_minor_performance_optimization branch from 7da7c8f to 3fd5486 Compare September 18, 2025 14:29

Brooooooklyn force-pushed the 09-18-perf_rolldown_take_advantage_of_tokio_blocking_threads branch from cec96a5 to 38cfd74 Compare September 18, 2025 14:29

IWANABETHATGUY approved these changes Sep 18, 2025

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Brooooooklyn force-pushed the 09-18-perf_rolldown_minor_performance_optimization branch from 3fd5486 to 1c71f7e Compare September 18, 2025 14:45

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IWANABETHATGUY added the graphite: merge label Sep 18, 2025

graphite-app bot changed the base branch from 09-18-perf_rolldown_take_advantage_of_tokio_blocking_threads to graphite-base/6271 September 18, 2025 17:12

graphite-app bot changed the base branch from graphite-base/6271 to main September 18, 2025 17:20

perf(rolldown): minor performance optimization (#6271)

230eae6

- pre-allocate memory - use simdutf8 rather than String utf8 check - avoid double utf8 checks in text_to_string_literal

graphite-app bot force-pushed the 09-18-perf_rolldown_minor_performance_optimization branch from 1c71f7e to 230eae6 Compare September 18, 2025 17:21

graphite-app bot merged commit 230eae6 into main Sep 18, 2025
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graphite-app bot deleted the 09-18-perf_rolldown_minor_performance_optimization branch September 18, 2025 17:33

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github-actions bot mentioned this pull request Sep 22, 2025

release: v1.0.0-beta.39 #6304

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This was referenced Sep 22, 2025

chore: adjust the tokio runtime config in bench #6305

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perf(rolldown): some minor perf optimization #6306

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perf(rolldown): minor performance optimization#6271

perf(rolldown): minor performance optimization#6271
graphite-app[bot] merged 1 commit intomainfrom
09-18-perf_rolldown_minor_performance_optimization

Brooooooklyn commented Sep 18, 2025

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Pull Request Overview

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Benchmarks Rust

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Brooooooklyn commented Sep 18, 2025 •

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