perf(linter/plugins): pre-populate cache of `EnterExit` objects by overlookmotel · Pull Request #20187 · oxc-project/oxc

overlookmotel · 2026-03-10T10:24:49Z

Perf optimization to visitor compilation.

Previously in the main loop for non-leaf visitors in finalizeCompiledVisitor, every turn of the loop had to check if cache contains an EnterExit object it can reuse, and to create a new one if not.

Instead, pre-populate the cache of EnterExit object before that main loop, to ensure there are always enough in the main loop.

After warmup over the first few files, the cache will be populated with enough EnterExit objects to service every file, and the "populate" loop will be skipped entirely.

This converts what was 1 branch per loop iteration to 1 highly predictable branch per file.

overlookmotel · 2026-03-10T10:25:02Z

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Pull request overview

Optimizes JS visitor compilation in apps/oxlint by ensuring the EnterExit object cache is pre-sized before the main non-leaf merge loop, reducing per-iteration branching in a hot path.

Changes:

Replace enterExitObjectCacheNextIndex with activeNonLeafVisitorsCount to track how many cached EnterExit objects are in use.
Pre-populate enterExitObjectCache up front in finalizeCompiledVisitor, then index directly into the cache during merging.
Update resetCompiledVisitor to clear only the EnterExit objects used by the last compilation.

apps/oxlint/src-js/plugins/visitor.ts

graphite-app · 2026-03-10T11:47:52Z

Merge activity

Mar 10, 11:47 AM UTC: overlookmotel added this pull request to the Graphite merge queue.
Mar 10, 12:01 PM UTC: Merged by the Graphite merge queue.

Perf optimization to visitor compilation. Previously in the main loop for non-leaf visitors in `finalizeCompiledVisitor`, every turn of the loop had to check if cache contains an `EnterExit` object it can reuse, and to create a new one if not. Instead, pre-populate the cache of `EnterExit` object *before* that main loop, to ensure there are always enough in the main loop. After warmup over the first few files, the cache will be populated with enough `EnterExit` objects to service every file, and the "populate" loop will be skipped entirely. This converts what was 1 branch per loop iteration to 1 highly predictable branch per file.

Perf optimization to visitor compilation. Apply the same optimization as #20187 to the cache of `VisitProp` objects. Instead of main loop in `addVisitorToCompiled` checking on each turn of the loop whether cache contains a `VisitProp` object it can reuse, instead pre-populate the cache to ensure it always does.

…artup (#20194) Perf optimization to visitor compilation. Continuation of #20187. Instead of populating the cache of `EnterExit` objects in `finalizeCompiledVisitor`, populate it in full at process startup. The main gain is that it makes these objects, which are heavily accessed during AST walk, more likely to be grouped together in memory, reducing L1 cache misses, and consuming less L1 cache.

# Oxlint ### 🚀 Features - 04a5ce0 oxlint: Support `vite.config.ts` `.lint` field (#20214) (leaysgur) - 1735215 linter: Implement `react/no-clone-element` rule. (#20129) (connorshea) - 68e6f6f linter: Implement `react/no-react-children` rule. (#20104) (connorshea) - fe3b32e linter/plugins: Add `oxlint-plugin-eslint` package (#20009) (overlookmotel) ### 🐛 Bug Fixes - 05f6a09 linter/no-inline-comments: Deserialize rule options with serde (#20207) (camc314) - c7eb09d linter/default-case: Deserialize rule options with serde (#20206) (camc314) - f85e16c linter/plugins: Fix types for visitor compilation (#20203) (overlookmotel) - 44e24e0 linter/exhaustive-deps: Ignore type-only typeof deps (#20201) (camc314) - 0b04998 linter/no-fallthrough: Deserialize rule options with serde (#20192) (camc314) - a1031cb linter/new-cap: Deserialize rule options with serde (#20161) (camc314) - ad27fd6 linter: Add help messages to import plugin diagnostics (#20158) (John Costa) - 1340307 linter/plugins: Ensure `after` hooks always run (#20167) (overlookmotel) - c4812ec linter/plugins: Reset visitor compilation state if error during compilation (#20166) (overlookmotel) - 887eecc linter/plugins: Add license notice to `oxlint-plugin-eslint` package (#20164) (overlookmotel) - e1713a4 linter/plugins: Include common chunks in `oxlint-plugin-eslint` package (#20163) (overlookmotel) - a9acb2b linter: Check `globals` entry for `no-undef`, only check es2026 globals for `no-extend-native` and `no-constant-binary-expression` (#20089) (Sysix) - 5559f0d linter/no-unused-vars: `reportUsedIgnorePattern` should not report used rest siblings (#20108) (Don Isaac) - de7c0e2 linter/plugins: Correct error message for `markVariableAsUsed` (#20152) (overlookmotel) ### ⚡ Performance - 3a86427 linter/plugins: Pre-populate cache of `EnterExit` objects at startup (#20194) (overlookmotel) - d243391 linter/plugins: Replace arrays with `Uint8Array`s (#20190) (overlookmotel) - 8742f8b linter/plugins: Pre-populate cache of `VisitProp` objects (#20189) (overlookmotel) - 3061acb linter/plugins: Pre-populate cache of `EnterExit` objects (#20187) (overlookmotel) - c73912b linter/plugins: Free visit functions earlier (#20186) (overlookmotel) - d9f8ff4 linter/plugins: Faster reset of visitor state (#20185) (overlookmotel) - 42aff15 oxlint/lsp: Avoid computing diagnostics for non invoked code actions requests (#20080) (Sysix) ### 📚 Documentation - a080650 linter/plugins: Fix documentation of visitor compilation (#20202) (overlookmotel) - 542a04a linter: Add a link to the cyclomatic complexity Wikipedia article in `eslint/complexity` (#20174) (connorshea) # Oxfmt ### 🚀 Features - 95943aa oxfmt: Support `vite.config.*` `.fmt` field (#20197) (leaysgur) - 172fc07 oxfmt: .js/.ts config file support (#20135) (leaysgur) ### 🐛 Bug Fixes - e483569 oxfmt: Avoid double-escaping in css-in-js (#20211) (leaysgur) Co-authored-by: leaysgur <6259812+leaysgur@users.noreply.github.com>

This was referenced Mar 10, 2026

perf(linter/plugins): faster reset of visitor state #20185

Merged

perf(linter/plugins): free visit functions earlier #20186

Merged

github-actions bot added A-linter Area - Linter A-cli Area - CLI A-linter-plugins Area - Linter JS plugins C-performance Category - Solution not expected to change functional behavior, only performance labels Mar 10, 2026

overlookmotel marked this pull request as ready for review March 10, 2026 10:46

overlookmotel requested a review from camc314 as a code owner March 10, 2026 10:46

Copilot AI review requested due to automatic review settings March 10, 2026 10:46

overlookmotel self-assigned this Mar 10, 2026

Copilot started reviewing on behalf of overlookmotel March 10, 2026 10:47 View session

This was referenced Mar 10, 2026

perf(linter/plugins): pre-populate cache of VisitProp objects #20189

Merged

perf(linter/plugins): replace arrays with Uint8Arrays #20190

Merged

Copilot AI reviewed Mar 10, 2026

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apps/oxlint/src-js/plugins/visitor.ts Outdated Show resolved Hide resolved

overlookmotel force-pushed the om/03-10-perf_linter_plugins_pre-populate_cache_of_enterexit_objects branch from a49e3e4 to f32b86c Compare March 10, 2026 11:24

graphite-app bot added the 0-merge Merge with Graphite Merge Queue label Mar 10, 2026

graphite-app bot force-pushed the om/03-09-perf_linter_plugins_free_visit_functions_earlier branch from 8a74e77 to c73912b Compare March 10, 2026 11:48

graphite-app bot force-pushed the om/03-10-perf_linter_plugins_pre-populate_cache_of_enterexit_objects branch from f32b86c to 3061acb Compare March 10, 2026 11:49

graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Mar 10, 2026

Base automatically changed from om/03-09-perf_linter_plugins_free_visit_functions_earlier to main March 10, 2026 12:00

graphite-app bot merged commit 3061acb into main Mar 10, 2026
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graphite-app bot deleted the om/03-10-perf_linter_plugins_pre-populate_cache_of_enterexit_objects branch March 10, 2026 12:01

overlookmotel mentioned this pull request Mar 10, 2026

perf(linter/plugins): pre-populate cache of EnterExit objects at startup #20194

Merged

Boshen mentioned this pull request Mar 11, 2026

release(apps): oxlint v1.53.0 && oxfmt v0.38.0 #20218

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overlookmotel mentioned this pull request Mar 13, 2026

perf(linter/plugins): move creating merger functions off hot path #20314

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perf(linter/plugins): pre-populate cache of `EnterExit` objects#20187

perf(linter/plugins): pre-populate cache of `EnterExit` objects#20187
graphite-app[bot] merged 1 commit intomainfrom
om/03-10-perf_linter_plugins_pre-populate_cache_of_enterexit_objects

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