perf(parser): faster checking for invalid modifiers

[overlookmotel]

Modifiers contains 2 different representations of the modifiers list:

• ModifierFlags bitflags
• Vec<Modifier>

When checking modifiers, use ModifierFlags (which is really cheap), rather than iterating through the Vec<Modifier> (more expensive).

Only if the first check fails, then loop through the Vec to get the spans of the invalid modifiers, and generate diagnostics.

Because invalid modifiers are rare, move the logic for looping through the Vec into a #[cold] #[inline(never)] function. This should make it possible to inline verify_modifiers into all the call sites.

Produces a small perf improvement on parser benchmarks (+0.1% - +0.2%).

[overlookmotel]

• perf(parser): faster checking for invalid modifiers #15717 👈 (View in Graphite)
• main

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[codspeed-hq]

CodSpeed Performance Report

Merging #15717 will not alter performance

_{Comparing 11-15-perf_parser_faster_checking_for_invalid_modifiers (624bb75) with main (d8d4e31)¹}

Summary

✅ 37 untouched

Footnotes

1. No successful run was found on main (4608549) during the generation of this report, so d8d4e31 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[Copilot]

Pull Request Overview

This PR optimizes the modifier checking logic in the parser by using bitflag operations instead of iterating through vectors. The key performance improvement comes from checking ModifierFlags (bitflags) first, and only looping through the Vec<Modifier> to get spans for diagnostics when invalid modifiers are detected.

Key changes:

• Added contains_all_flags method to check multiple flags efficiently
• Refactored verify_modifiers to use bitflag intersection check before iterating modifiers
• Moved error reporting logic into a #[cold] #[inline(never)] function to enable better inlining of the main verification function

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
crates/oxc_parser/src/modifiers.rs	Added contains_all_flags method and refactored verify_modifiers to check bitflags first, with cold error reporting path
crates/oxc_parser/src/js/class.rs	Updated all verify_modifiers call sites to use bitflag negation syntax and adapted to new diagnostic function signatures
crates/oxc_parser/src/ts/types.rs	Replaced manual loop with verify_modifiers call using bitflag negation
crates/oxc_parser/src/diagnostics.rs	Updated modifiers_cannot_appear_here signature to match standard modifier diagnostic pattern

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[Boshen]

Merge activity

• Nov 16, 3:03 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Nov 16, 3:03 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Nov 16, 3:14 AM UTC: Merged by the Graphite merge queue.