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fix(minifier): inline multiple variable declarations at once#13477

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graphite-app[bot] merged 1 commit intomainfrom
08-31-fix_minifier_inline_multiple_variable_declarations_at_once
Aug 31, 2025
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fix(minifier): inline multiple variable declarations at once#13477
graphite-app[bot] merged 1 commit intomainfrom
08-31-fix_minifier_inline_multiple_variable_declarations_at_once

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@sapphi-red sapphi-red commented Aug 31, 2025 •
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Codes like:

var a1 = 'a1'
var a2 = 'a2'
var a3 = 'a3'
var arr = [
  a1,
  a2,
  a3,
]
console.log(arr)

was not processed at once for DCE because DCE does not join variable declarations.
This PR fixes that.

This was referenced Aug 31, 2025
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sapphi-red commented Aug 31, 2025 •
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@github-actions github-actions bot added A-minifier Area - Minifier C-bug Category - Bug labels Aug 31, 2025
@sapphi-red sapphi-red changed the base branch from 08-31-feat_minifier_return_total_iterations_ran_for_dce_as_well to graphite-base/13477 August 31, 2025 13:19
@sapphi-red sapphi-red force-pushed the graphite-base/13477 branch from 7c96301 to 5990f17 Compare August 31, 2025 13:19
@sapphi-red sapphi-red force-pushed the 08-31-fix_minifier_inline_multiple_variable_declarations_at_once branch from ff4180d to ff425d0 Compare August 31, 2025 13:19
@sapphi-red sapphi-red changed the base branch from graphite-base/13477 to main August 31, 2025 13:19
@sapphi-red sapphi-red marked this pull request as ready for review August 31, 2025 13:22
Copilot AI review requested due to automatic review settings August 31, 2025 13:22
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Pull Request Overview

This PR fixes a dead code elimination (DCE) issue where multiple variable declarations were not inlined in a single pass. The minifier now iteratively processes variable declarations to fully inline multiple unused variables at once, improving the optimization efficiency.

  • Modified the inlining logic to use a loop instead of single-pass processing
  • Added comprehensive test coverage for the multi-iteration DCE scenario
  • Changed return logic to track whether any inlining occurred across iterations

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File Description
crates/oxc_minifier/src/peephole/minimize_statements.rs Updated variable inlining logic to process multiple declarations iteratively
crates/oxc_minifier/tests/peephole/dead_code_elimination.rs Added test case with 20 variables to verify multi-iteration DCE behavior

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@sapphi-red sapphi-red mentioned this pull request Aug 31, 2025
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codspeed-hq bot commented Aug 31, 2025 •
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CodSpeed Instrumentation Performance Report

Merging #13477 will not alter performance

Comparing 08-31-fix_minifier_inline_multiple_variable_declarations_at_once (946669b) with main (ecf69bb)1

Summary

✅ 37 untouched benchmarks

Footnotes

  1. No successful run was found on main (78dcfc6) during the generation of this report, so ecf69bb was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

@Boshen Boshen added the 0-merge Merge with Graphite Merge Queue label Aug 31, 2025
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Boshen commented Aug 31, 2025 •
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Merge activity

@sapphi-red
fix(minifier): inline multiple variable declarations at once (#13477)
946669b 
Codes like:
```js
var a1 = 'a1'
var a2 = 'a2'
var a3 = 'a3'
var arr = [
  a1,
  a2,
  a3,
]
console.log(arr)
```
was not processes at once for DCE because DCE does not join variable declarations.
This PR fixes that.
@graphite-app graphite-app bot force-pushed the 08-31-fix_minifier_inline_multiple_variable_declarations_at_once branch from ff425d0 to 946669b Compare August 31, 2025 15:09
@graphite-app graphite-app bot merged commit 946669b into main Aug 31, 2025
25 checks passed
@graphite-app graphite-app bot deleted the 08-31-fix_minifier_inline_multiple_variable_declarations_at_once branch August 31, 2025 15:15
@graphite-app graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Aug 31, 2025
@oxc-bot oxc-bot mentioned this pull request Sep 8, 2025
Merged
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