perf(allocator): add #[cold] annotations to error handling functions#18181
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graphite-app[bot] merged 1 commit intomainfrom Jan 18, 2026
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perf(allocator): add #[cold] annotations to error handling functions#18181graphite-app[bot] merged 1 commit intomainfrom
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Pull request overview
This PR adds performance optimization attributes (#[cold] and #[inline(never)]) to error handling and panic functions in the oxc_allocator crate to improve branch prediction and code layout for hot allocation paths.
Changes:
- Added
#[cold]attribute toallocation_size_overflowinbump.rs(already had#[inline(never)]) - Added both
#[cold]and#[inline(never)]attributes tonew_layout_errandhandle_alloc_errorinbumpalo_alloc.rs - Added both
#[cold]and#[inline(never)]attributes tocapacity_overflowinvec2/raw_vec.rs
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
crates/oxc_allocator/src/bump.rs |
Added #[cold] to allocation_size_overflow function |
crates/oxc_allocator/src/bumpalo_alloc.rs |
Added #[cold] and #[inline(never)] to new_layout_err and handle_alloc_error functions |
crates/oxc_allocator/src/vec2/raw_vec.rs |
Added #[cold] and #[inline(never)] to capacity_overflow function |
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…18181) ## Summary - Add `#[cold]` and `#[inline(never)]` annotations to error/panic functions in oxc_allocator - Improves branch prediction and code layout for hot allocation paths ### Functions annotated | File | Function | Change | |------|----------|--------| | `bump.rs` | `allocation_size_overflow` | Added `#[cold]` | | `bumpalo_alloc.rs` | `new_layout_err` | Added `#[cold]` + `#[inline(never)]` | | `bumpalo_alloc.rs` | `handle_alloc_error` | Added `#[cold]` + `#[inline(never)]` | | `vec2/raw_vec.rs` | `capacity_overflow` | Added `#[cold]` + `#[inline(never)]` | ### Impact The `#[cold]` attribute tells the compiler to: 1. Assume branches leading to these functions are unlikely 2. Move cold code away from hot paths (improves i-cache locality) 3. Avoid inlining cold functions into hot callers ## Test plan - [x] `cargo test -p oxc_allocator` passes 🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Summary
#[cold]and#[inline(never)]annotations to error/panic functions in oxc_allocatorFunctions annotated
bump.rsallocation_size_overflow#[cold]bumpalo_alloc.rsnew_layout_err#[cold]+#[inline(never)]bumpalo_alloc.rshandle_alloc_error#[cold]+#[inline(never)]vec2/raw_vec.rscapacity_overflow#[cold]+#[inline(never)]Impact
The
#[cold]attribute tells the compiler to:Test plan
cargo test -p oxc_allocatorpasses🤖 Generated with Claude Code