refactor: calculate side-effect-free function symbols on demand by IWANABETHATGUY · Pull Request #9120 · rolldown/rolldown

IWANABETHATGUY · 2026-04-15T11:14:19Z

Summary

Replaces pre-computed FxHashSet with on-demand O(1) lookups via a new SymbolRef::is_side_effect_free_function() method.
Eliminates the upfront sequential scan of all modules/symbols and the HashSet allocation in both the link and generate stages.
Since the checks now happen inside par_iter loops rather than in a sequential pre-computation step, the work is distributed across worker threads - each thread only checks the symbols it actually encounters.

IWANABETHATGUY · 2026-04-15T11:14:32Z

refactor: calculate side-effect-free function symbols on demand #9120 👈 (View in Graphite)
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netlify · 2026-04-15T11:14:36Z

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codspeed-hq · 2026-04-15T12:21:19Z

Merging this PR will not alter performance

✅ 4 untouched benchmarks
⏩ 10 skipped benchmarks¹

_{Comparing refactor/on-demand-side-effect-free-fn (3184ac5) with main (d94e51e)²}

10 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩
No successful run was found on main (3184ac5) during the generation of this report, so d94e51e was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

graphite-app · 2026-04-15T12:35:08Z

Merge activity

Apr 15, 12:35 PM UTC: IWANABETHATGUY added this pull request to the Graphite merge queue.
Apr 15, 12:41 PM UTC: Merged by the Graphite merge queue.

## Summary - Replaces pre-computed FxHashSet<SymbolRef> with on-demand O(1) lookups via a new SymbolRef::is_side_effect_free_function() method. - Eliminates the upfront sequential scan of all modules/symbols and the HashSet allocation in both the link and generate stages. - Since the checks now happen inside par_iter loops rather than in a sequential pre-computation step, the work is distributed across worker threads - each thread only checks the symbols it actually encounters.

@Dunqing

## [1.0.0-rc.16] - 2026-04-16 ### 🚀 Features - const enum cross-module inlining support (#8796) by @Dunqing - implement module tagging system for code splitting (#9045) by @hyf0 ### 🐛 Bug Fixes - rolldown_plugin_vite_manifest: handle duplicate chunk names for CSS entries (#9059) by @sapphi-red - improve error message for invalid return values in function options (#9125) by @shulaoda - await async export-star init wrappers (#9101) by @thezzisu - never panic during diagnostic emission (#9091) by @IWANABETHATGUY - include array rest pattern in binding_identifiers (#9112) by @IWANABETHATGUY - rolldown: set worker thread count with ROLLDOWN_WORKER_THREADS (#9086) by @fpotter - rolldown_plugin_lazy_compilation: escape request ID in proxy modules (#9102) by @h-a-n-a - treat namespace member access as side-effect-free (#9099) by @IWANABETHATGUY - relax overly conservative side-effect leak check in chunk optimizer (#9085) by @IWANABETHATGUY - runtime: release `cb` reference after `__commonJS` factory initialization (#9067) by @hyf0-agent - `@__NO_SIDE_EFFECTS__` wrapper should not remove dynamic imports (#9075) by @IWANABETHATGUY - rolldown_plugin_vite_import_glob: use POSIX path join/normalize for glob resolution (#9077) by @shulaoda - emit REQUIRE_TLA error when require() loads a module with top-level await (#9071) by @jaehafe - emit namespace declaration for empty modules in manual chunks (#8993) by @privatenumber - rolldown_plugin_vite_import_glob: keep common base on path segment boundary (#9070) by @shulaoda - prevent circular runtime helper imports during facade elimination (#8989) (#9057) by @IWANABETHATGUY - correct circular dependency check in facade elimination (#9047) by @h-a-n-a - docs: correct dead link in CodeSplittingGroup.tags JSDoc (#9051) by @hyf0 - emit DUPLICATE_SHEBANG warning when banner contains shebang (#9026) by @IWANABETHATGUY ### 🚜 Refactor - use semantic reference flags for member write detection (#9060) by @Dunqing - extract UsedSymbolRefs newtype wrapper (#9130) by @IWANABETHATGUY - dedupe await wrapping in export-star init emit (#9119) by @IWANABETHATGUY - calculate side-effect-free function symbols on demand (#9120) by @IWANABETHATGUY - extract duplicated top-level await handling into shared helper (#9087) by @IWANABETHATGUY - rolldown_plugin_vite_import_glob: use split_first for get_common_base (#9069) by @shulaoda - simplify ESM init deduplication with idiomatic insert check (#9044) by @IWANABETHATGUY ### 📚 Documentation - document runtime module placement strategy in code-splitting design (#9062) by @IWANABETHATGUY - clarify `options` hook behavior difference with Rollup in watch mode (#9053) by @sapphi-red - meta/design: introduce module tags (#9017) by @hyf0 ### ⚡ Performance - convert `generate_transitive_esm_init` to iterative (#9046) by @IWANABETHATGUY ### 🧪 Testing - merge strict/non_strict test variants using configVariants (#9089) by @IWANABETHATGUY ### ⚙️ Miscellaneous Tasks - disable Renovate auto-updates for oxc packages (#9129) by @IWANABETHATGUY - upgrade oxc@0.126.0 (#9127) by @Dunqing - deps: update napi to v3.8.5 (#9126) by @renovate[bot] - deps: update dependency @napi-rs/cli to v3.6.2 (#9123) by @renovate[bot] - move lazy-compilation design doc (#9117) by @h-a-n-a - deps: update dependency vite-plus to v0.1.18 (#9118) by @renovate[bot] - deps: update dependency vite-plus to v0.1.17 (#9113) by @renovate[bot] - deps: update oxc to v0.125.0 (#9094) by @renovate[bot] - deps: update dependency follow-redirects to v1.16.0 [security] (#9103) by @renovate[bot] - deps: update test262 submodule for tests (#9097) by @sapphi-red - deps: update crate-ci/typos action to v1.45.1 (#9096) by @renovate[bot] - deps: update rust crates (#9081) by @renovate[bot] - deps: update npm packages (#9080) by @renovate[bot] - remove outdated TODO in determine_module_exports_kind (#9072) by @jaehafe - rust/test: support `extendedTests: false` shorthand in test config (#9050) by @hyf0 - ci: extract shared infra-changes anchor in path filters (#9054) by @hyf0 - add docs build check to catch dead links in PRs (#9052) by @hyf0 ### ❤️ New Contributors * @thezzisu made their first contribution in [#9101](#9101) * @fpotter made their first contribution in [#9086](#9086) * @jaehafe made their first contribution in [#9071](#9071) * @privatenumber made their first contribution in [#8993](#8993) Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>

github-actions Bot assigned IWANABETHATGUY Apr 15, 2026

IWANABETHATGUY changed the title u refactor: calculate side-effect-free function symbols on demand Apr 15, 2026

IWANABETHATGUY force-pushed the refactor/on-demand-side-effect-free-fn branch from 0a3fb16 to b25da23 Compare April 15, 2026 12:08

IWANABETHATGUY requested review from h-a-n-a, hyf0 and shulaoda April 15, 2026 12:15

IWANABETHATGUY marked this pull request as ready for review April 15, 2026 12:15

hyf0 approved these changes Apr 15, 2026

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graphite-app Bot force-pushed the refactor/on-demand-side-effect-free-fn branch from b25da23 to 3184ac5 Compare April 15, 2026 12:36

graphite-app Bot merged commit 3184ac5 into main Apr 15, 2026
31 of 32 checks passed

graphite-app Bot deleted the refactor/on-demand-side-effect-free-fn branch April 15, 2026 12:41

github-actions Bot mentioned this pull request Apr 16, 2026

release: v1.0.0-rc.16 #9131

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refactor: calculate side-effect-free function symbols on demand#9120

refactor: calculate side-effect-free function symbols on demand#9120
graphite-app[bot] merged 1 commit intomainfrom
refactor/on-demand-side-effect-free-fn

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IWANABETHATGUY commented Apr 15, 2026

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