perf(mangler): do not sort Vec if empty

[overlookmotel]

Tiny optimization to mangler. We sort a Vec and then check if it's empty. Move the empty check to be first, so can skip sorting in that case.

[overlookmotel]

• perf(mangler): store slot indexes as u32s #13462
• perf(mangler): do not sort Vec if empty #13461 👈 (View in Graphite)
• main

---

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• 0-merge - adds this PR to the back of the merge queue
• hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[Copilot]

Pull Request Overview

This PR implements a small performance optimization in the mangler by reordering an empty check before a sort operation to avoid unnecessary sorting of empty vectors.

• Moves the empty check for tmp_bindings before the sort_unstable() call
• Prevents sorting when the vector is empty, saving computational cycles

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #13461 will not alter performance

_{Comparing 08-31-perf_mangler_do_not_sort_vec_if_empty (caf40c5) with main (b92fa4f)¹}

Summary

✅ 37 untouched benchmarks

Footnotes

1. No successful run was found on main (caf40c5) during the generation of this report, so b92fa4f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[graphite-app]

Merge activity

• Aug 31, 10:25 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Aug 31, 10:30 AM UTC: Merged by the Graphite merge queue.