fix(minifier): bail out arguments copy loop substitution if the temporary variables are referenced outside the for loop

[sapphi-red]

fixes rolldown/rolldown#6458
refs #13114

[sapphi-red]

• fix(minifier): bail out arguments copy loop substitution if the temporary variables are referenced outside the for loop #14613 👈 (View in Graphite)
• main

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[Copilot]

Pull Request Overview

This PR fixes a bug in the minifier's arguments copy loop substitution optimization where temporary variables referenced outside the for loop were incorrectly being optimized away. The fix adds proper validation to ensure variables are only referenced within the loop before applying the substitution.

Key changes:

• Add reference counting for temporary variables a and e within the for loop
• Implement validation to bail out of optimization if variables are referenced outside the loop
• Refactor return types to use enum for better type safety

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[codspeed-hq]

CodSpeed Performance Report

Merging #14613 will not alter performance

_{Comparing 10-15-fix_minifier_bail_out_arguments_copy_loop_substitution_if_the_temporary_variables_are_referenced_outside_the_for_loop (1bf83eb) with main (1b58521)¹}

Summary

✅ 33 untouched
⏩ 4 skipped²

Footnotes

1. No successful run was found on main (5e0ab1b) during the generation of this report, so 1b58521 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 4 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. ↩

[Boshen]

Merge activity

• Oct 15, 5:25 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Oct 15, 5:25 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Oct 15, 5:36 AM UTC: Merged by the Graphite merge queue.

[lazka]

Thanks!