perf(linter/plugins): avoid arguments spread and temp array when merging#20318
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Pull request overview
This PR optimizes the visitor compilation pipeline in oxlint by removing argument spreading and a temporary array when merging visit functions, reducing overhead during visitor compilation and keeping merged visitor functions lean for hot-path AST traversal.
Changes:
- Change merger function signatures to accept
VisitProp[]/CfgVisitProp[]directly instead of(...visitFns). - Update
mergeVisitFns/mergeCfgVisitFnsto passvisitPropsdirectly to the appropriate merger. - Update dynamically generated mergers (
createMerger) and pre-defined merger tables to destructure.fnfromvisitPropsinternally.
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…ing (#20318) Perf optimization to merging visit function when compiling AST visitors. Previously we took an array of `VisitProp` objects, extracted the `fn` property from each into a temporary array, and then called the merger function using spread `merger(...visitFns)`. Remove the temp array and the mapping entirely by just passing the arrays of `VisitProp` objects directly to the merger function, and destructuring it internally. This is simpler and also more performant. My concern with taking this approach originally was that the merged functions might capture the `VisitProp[]` passed in to outer function in its scope, which would bloat them. These functions are extremely hot - called 1,000s or 10,000s of times during AST visitation - so even a small slow-down in these functions would be measurable. But analysis using V8 built-in functions (`%DebugPrint`) to inspect what these functions capture in their scopes reveals that this concern was unwarranted - they only capture the variables that they actually use, and do not capture to `VisitProp[]` arrays. So they are unchanged after this PR.
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# Oxlint ### 🚀 Features - c95951f linter/plugins: Implement `sourceCode.markVariableAsUsed` (#20357) (overlookmotel) - 7a2a7d0 linter: Implement `n/handle-callback-err` rule (#19616) (Mikhail Baev) ### 🐛 Bug Fixes - f8fbd6e linter/plugins: Remove `hashbang` property from AST (#20365) (overlookmotel) - 6eb5b01 linter/prefer-await-to-then: Ignore Promise static methods (#20347) (camc314) - a4b61f7 linter: Remove `defineConfig` check (#20308) (camc314) - 3ad7f53 linter/explicit-module-boundary-types: False positive with satisfies expr (#20309) (camc314) - f547401 linter/no-unused-private-class-members: Treat switch discriminants as read (#20307) (camc314) - 1c07b3b diagnostics: Handle `WouldBlock` in stdout writes to prevent panic (#20295) (Boshen) ### ⚡ Performance - e4f7248 linter: Remove unnecessary clone of owned String in drain loop (#20388) (Boshen) - 4a67f1d linter: Eliminate Vec allocation in disable directive matching (#20387) (Boshen) - 618a598 linter/plugins: Add fast path for files with no comments (#20366) (overlookmotel) - b0125c5 linter/plugins: Deserialize comments without AST (#20364) (overlookmotel) - 9cd612f linter/plugins: Recycle comment objects (#20362) (overlookmotel) - bf442f8 linter/plugins: Cheaper `Token` creation (#20360) (overlookmotel) - 5474d0a semantic: V8-style walk-up reference resolution (#20292) (Boshen) - 7946eba linter/plugins: Avoid arguments spread and temp array when merging (#20318) (overlookmotel) - fc7cf8a linter/plugins: Pre-define less CFG merger functions (#20317) (overlookmotel) - 3b9eb28 linter/plugins: Streamline getting/creating visit fn mergers (#20319) (overlookmotel) - f04e850 linter/plugins: Inline binary search functions into call sites (#20312) (overlookmotel) - fe24afe linter/plugins: Apply replace globals TSDown plugin to JS files (#20305) (overlookmotel) - 77cdacc linter/plugins: Use array buffer views for tokens (#20301) (overlookmotel) - 910c941 linter/plugins: Reorder branches in `getTokenByRangeStart` (#20296) (overlookmotel) - af7674c linter/tokens: Avoid extra token value allocation (#20013) (camc314) ### 📚 Documentation - 24490b5 linter: Improve formatting for 80ish rules' docs. (#20411) (connorshea) - 3383523 linter: Improve `--tsconfig` flag docs (#20342) (camc314) # Oxfmt ### 🚀 Features - d22c443 oxfmt: Export `OxfmtConfig` type (#20275) (leaysgur) - a11ecff oxfmt/lsp: Respect `angular` language id as `.component.html` file (#20242) (Sysix) ### 🐛 Bug Fixes - ce65099 formatter: Preserve parentheses around as expression before private field access (#20419) (bab) - f908742 oxfmt: Revert #20326 partially (#20413) (leaysgur) - 4ef93ea formatter: Honor trailing ignore comments after list separators (#19925) (Andreas Lubbe) - 68fb0d0 oxfmt: Skip vite.config.ts which fails to import (#20326) (leaysgur) - 88ee826 oxfmt: Handle literalline for script-in-vue (#20130) (leaysgur) - 1c07b3b diagnostics: Handle `WouldBlock` in stdout writes to prevent panic (#20295) (Boshen) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
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Perf optimization to merging visit function when compiling AST visitors.
Previously we took an array of
VisitPropobjects, extracted thefnproperty from each into a temporary array, and then called the merger function using spreadmerger(...visitFns).Remove the temp array and the mapping entirely by just passing the arrays of
VisitPropobjects directly to the merger function, and destructuring it internally.This is simpler and also more performant.
My concern with taking this approach originally was that the merged functions might capture the
VisitProp[]passed in to outer function in its scope, which would bloat them. These functions are extremely hot - called 1,000s or 10,000s of times during AST visitation - so even a small slow-down in these functions would be measurable.But analysis using V8 built-in functions (
%DebugPrint) to inspect what these functions capture in their scopes reveals that this concern was unwarranted - they only capture the variables that they actually use, and do not capture toVisitProp[]arrays. So they are unchanged after this PR.