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perf(parser): avoid re-allocating when parsing import stmt#20666

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c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt
Mar 24, 2026
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perf(parser): avoid re-allocating when parsing import stmt#20666
graphite-app[bot] merged 1 commit intomainfrom
c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt

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@camc314 camc314 marked this pull request as ready for review March 23, 2026 21:32
Copilot AI review requested due to automatic review settings March 23, 2026 21:32
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camc314 commented Mar 23, 2026 •
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@github-actions github-actions bot added A-parser Area - Parser C-performance Category - Solution not expected to change functional behavior, only performance labels Mar 23, 2026
@camc314 camc314 mentioned this pull request Mar 23, 2026
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@camc314 camc314 force-pushed the c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt branch from b7bfa7f to 690724a Compare March 23, 2026 21:33
@camc314 camc314 force-pushed the c/03-23-perf_parser_avoid_vec_clone branch from 2d352a9 to 0373c67 Compare March 23, 2026 21:33
@camc314 camc314 force-pushed the c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt branch from 690724a to fefedb6 Compare March 23, 2026 21:34
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Pull request overview

Improves parser performance for import declarations by avoiding an intermediate allocation when parsing named import specifiers, reusing an existing arena Vec instead.

Changes:

  • Replaced parse_import_specifiers (returning a new Vec) with parse_import_specifiers_into that appends directly into an existing specifiers list.
  • Added parse_delimited_list_into helper to parse delimited lists into an existing arena Vec, avoiding re-allocation.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File Description
crates/oxc_parser/src/js/module.rs Switches import-specifier parsing to append into an existing specifiers vec to avoid creating a temporary vec.
crates/oxc_parser/src/cursor.rs Introduces parse_delimited_list_into to support parsing directly into an existing list.

@camc314 camc314 force-pushed the c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt branch from fefedb6 to 2cb0cb3 Compare March 23, 2026 21:36
@camc314 camc314 mentioned this pull request Mar 23, 2026
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codspeed-hq bot commented Mar 23, 2026

Merging this PR will not alter performance

✅ 53 untouched benchmarks
⏩ 3 skipped benchmarks1

Comparing c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt (2cb0cb3) with c/03-23-perf_parser_avoid_vec_clone (0373c67)

Open in CodSpeed

Footnotes

  1. 3 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. ↩

@graphite-app graphite-app bot added the 0-merge Merge with Graphite Merge Queue label Mar 24, 2026
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graphite-app bot commented Mar 24, 2026 •
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Merge activity

@graphite-app graphite-app bot force-pushed the c/03-23-perf_parser_avoid_vec_clone branch from 0373c67 to 2b2794b Compare March 24, 2026 04:01
@graphite-app graphite-app bot force-pushed the c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt branch from 2cb0cb3 to ad58dd7 Compare March 24, 2026 04:01
Base automatically changed from c/03-23-perf_parser_avoid_vec_clone to main March 24, 2026 04:04
@graphite-app graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Mar 24, 2026
@graphite-app graphite-app bot merged commit ad58dd7 into main Mar 24, 2026
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@graphite-app graphite-app bot deleted the c/03-23-perf_parser_avoid_re-allocating_when_parsing_import_stmt branch March 24, 2026 04:04
@Boshen Boshen mentioned this pull request Mar 30, 2026
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