perf(allocator/vec2): replace `self.reserve(1)` calls with `self.grow_one()` for better efficiency by Dunqing · Pull Request #9856 · oxc-project/oxc

Dunqing · 2025-03-18T08:06:06Z

The places calling self.reserve(1) already checked len == self.buf.cap(), in order to avoid checking again in reserve, we should call grow_one instead which is a shortcut of grow_amortized(len, 1).

Dunqing · 2025-03-18T08:06:27Z

perf(allocator/vec2): align min amortized cap size with std #9857
feat(allocator/vec2): align RawVec::reserve with standard library implementation #10701
perf(allocator/vec2): replace self.reserve(1) calls with self.grow_one() for better efficiency #9856 👈 (View in Graphite)
feat(allocator/vec2): add specialized grow_one method #9855
perf(allocator/vec2): calling Bump::grow or Bump::shrink at the call site directly instead of calling realloc #10686
perf(allocator/vec2): resolve performance regression for extend by marking reserve as #[cold] and #[inline(never)] #10675
feat(allocator/vec2): introduce extend_desugared method as extend internal implementation #10670
perf(transformer/refresh): use take/take_in instead of drain #10656
perf(transformer): optimize inserting var/let statements #10654
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codspeed-hq · 2025-03-18T08:11:14Z

CodSpeed Instrumentation Performance Report

Merging #9856 will not alter performance

_{Comparing 03-18-perf_allocator_vec2_replace_self.reserve_1_calls_with_self.grow_one_for_better_efficiency (04e0390) with main (7f2f247)}

Summary

✅ 36 untouched benchmarks

Dunqing · 2025-03-18T08:26:10Z

Unbelievable 😢

EDIT: This unbelievable result is due to my mistake.

Dunqing · 2025-03-19T02:56:29Z

I've noticed the current extend implementation will call the push method, extend is quite a common method for our scenario, so I think #[inline(never)] is a deoptimization. I decided to get #9881 done first and then continue this.

…marking reserve as `#[cold]` and `#[inline(never)]` (#10675) I guess the performance regression reason is that the current implementation has more instructions than before. Here to use the lower of `size_hint` to reserve space, which is bloating the loop body. Also, the `for` loop is easier to optimize by the compiler. `reserve` inside `extend` is rarely taken, so mark it as `#[cold]` and `#[inline(never)]`, which can reduce the instructions in `while` loop. We got a 3%-4% performance improvement in the `minfier`, but the transformer performance did not fully get back to before #10670. Anyway, I think we can accept the less than 1% performance regression; this change can unblock us from pushing forward the `Vec` improvement; we will get it back in at the end of the stack! See #9856

overlookmotel · 2025-05-03T14:33:11Z

Merge activity

May 3, 10:33 AM EDT: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
May 3, 10:52 AM EDT: overlookmotel added this pull request to the Graphite merge queue.
May 3, 11:10 AM EDT: Merged by the Graphite merge queue.

…_one()` for better efficiency (#9856) The places calling `self.reserve(1)` already checked `len == self.buf.cap()`, in order to avoid checking again in `reserve`, we should call `grow_one` instead which is a shortcut of `grow_amortized(len, 1)`.

coderabbitai · 2025-05-03T15:06:04Z

Walkthrough

This change updates the memory growth strategy in a custom vector implementation. Specifically, within the Vec type, the insert and push methods now call self.buf.grow_one() to increase capacity by one when needed, instead of the previous approach using self.reserve(1). This delegates the responsibility for buffer growth directly to the underlying RawVec's grow_one method. Additionally, the grow_one method in RawVec has its attribute changed from #[inline(never)] to #[inline], accompanied by a comment explaining that inlining is preferred for frequent use cases in the parser. No changes were made to the signatures of public or exported entities.

Possibly related PRs

feat(allocator/vec2): add specialized grow_one method #9855: This PR originally introduced the grow_one method in RawVec, which is now being directly utilized in the updated Vec methods for buffer growth.

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crates/oxc_allocator/src/vec2/mod.rs (2 hunks)
crates/oxc_allocator/src/vec2/raw_vec.rs (1 hunks)

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🔇 Additional comments (3)

crates/oxc_allocator/src/vec2/raw_vec.rs (1)

440-443: Improvement to grow_one inlining strategy.

The change from #[inline(never)] to #[inline] is appropriate for this function since it's a common case in the parser. The added comment clearly explains the rationale behind deviating from the standard library's approach.

crates/oxc_allocator/src/vec2/mod.rs (2)

1238-1241: Optimization by directly calling grow_one.

This change improves efficiency by replacing self.reserve(1) with self.buf.grow_one(). Since the code already checks if len == self.buf.cap(), using grow_one() directly avoids redundant capacity checks that would happen inside the reserve method.

1567-1569: Optimization by directly calling grow_one.

Similar to the change in the insert method, this change replaces self.reserve(1) with self.buf.grow_one() to avoid redundant capacity checks when growing the vector by one element.

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Dunqing mentioned this pull request Mar 18, 2025

feat(allocator/vec2): add specialized grow_one method #9855

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github-actions bot added the C-performance Category - Solution not expected to change functional behavior, only performance label Mar 18, 2025

Dunqing mentioned this pull request Mar 18, 2025

perf(allocator/vec2): align min amortized cap size with std #9857

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Dunqing mentioned this pull request Jan 18, 2026

Improve Vec2 oxc-project/backlog#199

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Dunqing force-pushed the 03-18-feat_allocator_vec2_add_specialized_grow_one_method branch from a305372 to b9a6398 Compare March 18, 2025 08:36

Dunqing force-pushed the 03-18-perf_allocator_vec2_replace_self.reserve_1_calls_with_self.grow_one_for_better_efficiency branch from 4dc483f to 9d1db26 Compare March 18, 2025 08:36

Dunqing mentioned this pull request Mar 18, 2025

refactor(allocator/vec2): rename parameters and method name to align with std #9858

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Dunqing force-pushed the 03-18-perf_allocator_vec2_replace_self.reserve_1_calls_with_self.grow_one_for_better_efficiency branch from 9d1db26 to c94a0f0 Compare March 18, 2025 08:59

Dunqing force-pushed the 03-18-feat_allocator_vec2_add_specialized_grow_one_method branch from b9a6398 to 9968328 Compare March 18, 2025 08:59

Dunqing force-pushed the 03-18-perf_allocator_vec2_replace_self.reserve_1_calls_with_self.grow_one_for_better_efficiency branch 7 times, most recently from 83b077f to 43613e1 Compare March 18, 2025 16:35

Dunqing marked this pull request as draft March 19, 2025 02:49

Dunqing force-pushed the 03-18-perf_allocator_vec2_replace_self.reserve_1_calls_with_self.grow_one_for_better_efficiency branch from 149392c to 901e287 Compare April 30, 2025 02:39

Dunqing changed the base branch from graphite-base/9856 to 03-18-feat_allocator_vec2_add_specialized_grow_one_method April 30, 2025 02:39

Dunqing force-pushed the 03-18-perf_allocator_vec2_replace_self.reserve_1_calls_with_self.grow_one_for_better_efficiency branch 2 times, most recently from 44dd469 to aae3118 Compare April 30, 2025 05:20

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overlookmotel approved these changes May 3, 2025

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overlookmotel changed the base branch from 03-18-feat_allocator_vec2_add_specialized_grow_one_method to graphite-base/9856 May 3, 2025 14:45

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release(crates): v0.68.0 #10777

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perf(allocator/vec2): replace `self.reserve(1)` calls with `self.grow_one()` for better efficiency#9856

perf(allocator/vec2): replace `self.reserve(1)` calls with `self.grow_one()` for better efficiency#9856
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