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perf: extend avoidEntryIife no-parse fast path to multi-entry chunks#21173

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alexander-akait merged 2 commits into
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perf/avoid-entry-iife-multi-entry-fast-path
Jun 12, 2026
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perf: extend avoidEntryIife no-parse fast path to multi-entry chunks#21173
alexander-akait merged 2 commits into
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perf/avoid-entry-iife-multi-entry-fast-path

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Summary

With optimization.avoidEntryIife, multi-entry chunks re-parsed every inlined concatenated entry (acorn + eslint-scope over the whole rendered app) on every build to check for name collisions. ConcatenatedModule codegen now also reports its free names, extending the single-entry no-parse fast path from #21167 to multi-entry chunks (rename step ~480ms → ~6ms on a 3k-module two-entry build, byte-identical output).

What kind of change does this PR introduce?

perf

Did you add tests for your changes?

Yes — test/configCases/module/iife-multiple-concatenated-entries (fast path taken) and test/configCases/module/iife-multiple-concatenated-entries-collision (fast path bails, renaming still applies).

Does this PR introduce a breaking change?

No.

If relevant, what needs to be documented once your changes are merged or what have you already documented?

n/a

Use of AI

AI (Claude Code) was used to implement the change, write the tests, and run the verification/benchmarks under maintainer direction; the result was reviewed before submission.

https://claude.ai/code/session_01AbYA9s4rUycBWPNyZbzP1Y


Generated by Claude Code

@changeset-bot

changeset-bot Bot commented Jun 11, 2026

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🦋 Changeset detected

Latest commit: c86c2b3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package
Name Type
webpack Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

@github-actions

github-actions Bot commented Jun 11, 2026

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This PR is packaged and the instant preview is available (04633bc).

Install it locally:

  • npm
npm i -D webpack@https://pkg.pr.new/webpack@04633bc
  • yarn
yarn add -D webpack@https://pkg.pr.new/webpack@04633bc
  • pnpm
pnpm add -D webpack@https://pkg.pr.new/webpack@04633bc

@codecov

codecov Bot commented Jun 11, 2026

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Codecov Report

❌ Patch coverage is 93.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.58%. Comparing base (5f01ae5) to head (c86c2b3).
⚠️ Report is 3 commits behind head on main.

Files with missing lines Patch % Lines
lib/javascript/JavascriptModulesPlugin.js 92.59% 2 Missing ⚠️
Additional details and impacted files
@@            Coverage Diff             @@
##             main   #21173      +/-   ##
==========================================
- Coverage   92.59%   92.58%   -0.01%     
==========================================
  Files         586      586              
  Lines       63750    63837      +87     
  Branches    17664    17691      +27     
==========================================
+ Hits        59028    59105      +77     
- Misses       4722     4732      +10     
Flag Coverage Δ
css-parsing 28.68% <0.00%> (-0.02%) ⬇️
html5lib 31.05% <0.00%> (-0.01%) ⬇️
integration 88.63% <93.33%> (-0.01%) ⬇️
test262 45.54% <73.33%> (+0.06%) ⬆️
unit 40.28% <0.00%> (-0.03%) ⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

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📢 Have feedback on the report? Share it here.

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@codspeed-hq

codspeed-hq Bot commented Jun 11, 2026

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Merging this PR will improve performance by 61.72%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 5 improved benchmarks
❌ 1 regressed benchmark
✅ 138 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

Mode Benchmark BASE HEAD Efficiency
Memory benchmark "asset-modules-inline", scenario '{"name":"mode-development-rebuild","mode":"development","watch":true}' 324 KB 1,073 KB -69.8%
Memory benchmark "lodash", scenario '{"name":"mode-development-rebuild","mode":"development","watch":true}' 858.1 KB 127.5 KB ×6.7
Memory benchmark "asset-modules-bytes", scenario '{"name":"mode-development-rebuild","mode":"development","watch":true}' 888.1 KB 321 KB ×2.8
Memory benchmark "side-effects-reexport", scenario '{"name":"mode-development-rebuild","mode":"development","watch":true}' 1,196.8 KB 759.6 KB +57.56%
Memory benchmark "devtool-eval-source-map", scenario '{"name":"mode-production","mode":"production"}' 8 MB 5.4 MB +47.86%
Memory benchmark "many-modules-commonjs", scenario '{"name":"mode-production","mode":"production"}' 9.9 MB 7.3 MB +36.53%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.


Comparing perf/avoid-entry-iife-multi-entry-fast-path (c86c2b3) with main (2a74860)

Open in CodSpeed

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Types Coverage

Coverage after merging perf/avoid-entry-iife-multi-entry-fast-path into main will be
99.35%
Coverage Report
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@alexander-akait alexander-akait merged commit 04633bc into main Jun 12, 2026
66 checks passed
@alexander-akait alexander-akait deleted the perf/avoid-entry-iife-multi-entry-fast-path branch June 12, 2026 09:12
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