Skip to content

perf(minifier): use ReplaceWith instead of TakeIn#24017

Merged
graphite-app[bot] merged 1 commit into
mainfrom
om/07-01-perf_minifier_use_replacewith_instead_of_takein_
Jul 9, 2026
Merged

perf(minifier): use ReplaceWith instead of TakeIn#24017
graphite-app[bot] merged 1 commit into
mainfrom
om/07-01-perf_minifier_use_replacewith_instead_of_takein_

Conversation

@overlookmotel

@overlookmotel overlookmotel commented Jul 1, 2026

Copy link
Copy Markdown
Member

Replace take_in with replace_with in as many places as possible in minifier. See #24012 for explanation of the advantage of replace_with.

Likely we could use replace_with in many more places, if we adapted the methods through which most replacement operations flow (which also track "dirty" state). I've left this for now, as I don't really understand the minifier.

overlookmotel commented Jul 1, 2026

Copy link
Copy Markdown
Member Author

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 changes, fast-track this PR to the front of the merge queue

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.

@codspeed-hq

codspeed-hq Bot commented Jul 1, 2026

Copy link
Copy Markdown

Merging this PR will not alter performance

✅ 52 untouched benchmarks
⏩ 19 skipped benchmarks1


Comparing om/07-01-perf_minifier_use_replacewith_instead_of_takein_ (3e70b22) with main (6ab439a)

Open in CodSpeed

Footnotes

  1. 19 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.

@overlookmotel
overlookmotel marked this pull request as ready for review July 1, 2026 16:40
@overlookmotel
overlookmotel requested a review from Dunqing as a code owner July 1, 2026 16:40
Copilot AI review requested due to automatic review settings July 1, 2026 16:40

Copilot AI left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Pull request overview

Updates the minifier’s peephole normalization to use the new ReplaceWith API (instead of take_in) where the original node is immediately overwritten, reducing unnecessary arena allocations and updating the tracked allocation snapshot accordingly.

Changes:

  • Refactor convert_while_to_for to use Statement::replace_with(...) when rewriting while into for.
  • Update allocs_minifier.snap to reflect reduced arena allocations from the change.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File Description
tasks/track_memory_allocations/allocs_minifier.snap Updates expected allocation counts after the minifier change.
crates/oxc_minifier/src/peephole/normalize.rs Uses ReplaceWith to avoid allocating dummy nodes during whilefor rewrites.

@overlookmotel
overlookmotel force-pushed the om/07-01-perf_minifier_use_replacewith_instead_of_takein_ branch from 4b6ee85 to c1fc2ce Compare July 1, 2026 18:01
@overlookmotel
overlookmotel force-pushed the om/07-01-perf_isolated_declarations_use_replacewith_instead_of_takein_ branch from 1d5370a to 0b6374a Compare July 1, 2026 18:01
@graphite-app
graphite-app Bot force-pushed the om/07-01-perf_isolated_declarations_use_replacewith_instead_of_takein_ branch from 0b6374a to 6c6b14d Compare July 2, 2026 01:40
@graphite-app
graphite-app Bot force-pushed the om/07-01-perf_minifier_use_replacewith_instead_of_takein_ branch from c1fc2ce to 5c8f03c Compare July 2, 2026 01:41
@overlookmotel
overlookmotel force-pushed the om/07-01-perf_isolated_declarations_use_replacewith_instead_of_takein_ branch from 6c6b14d to e1ad60b Compare July 2, 2026 21:50
@overlookmotel
overlookmotel force-pushed the om/07-01-perf_minifier_use_replacewith_instead_of_takein_ branch from 5c8f03c to 865115a Compare July 2, 2026 21:50
@overlookmotel

Copy link
Copy Markdown
Member Author

Likely we could use replace_with in many more places, if we adapted the methods through which most replacement operations flow (which also track "dirty" state). I've left this for now, as I don't really understand the minifier.

@Dunqing Just to draw your attention to this.

replace_expression, replace_statement etc I think could be adapted to use the same pattern as replace_with (taking a closure) and use replace_with internally. I'd guess this would greatly reduce allocations in the minifier. But I didn't want to touch it without talking to you first, as I wouldn't at all know what I'm doing in the minifier!

@graphite-app
graphite-app Bot changed the base branch from om/07-01-perf_isolated_declarations_use_replacewith_instead_of_takein_ to graphite-base/24017 July 5, 2026 14:45
@Dunqing

Dunqing commented Jul 7, 2026

Copy link
Copy Markdown
Member

Likely we could use replace_with in many more places, if we adapted the methods through which most replacement operations flow (which also track "dirty" state). I've left this for now, as I don't really understand the minifier.

@Dunqing Just to draw your attention to this.

replace_expression, replace_statement etc I think could be adapted to use the same pattern as replace_with (taking a closure) and use replace_with internally. I'd guess this would greatly reduce allocations in the minifier. But I didn't want to touch it without talking to you first, as I wouldn't at all know what I'm doing in the minifier!

Sounds good! Let me do it after I clean up my PRs in hand.

@graphite-app graphite-app Bot added the 0-merge Merge with Graphite Merge Queue label Jul 7, 2026
@graphite-app

graphite-app Bot commented Jul 7, 2026

Copy link
Copy Markdown
Contributor

Merge activity

  • Jul 7, 3:49 PM UTC: This pull request can not be added to the Graphite merge queue. Please try rebasing and resubmitting to merge when ready.
  • Jul 7, 3:49 PM UTC: Graphite disabled "merge when ready" on this PR due to: a merge conflict with the target branch; resolve the conflict and try again..
  • Jul 7, 3:50 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
  • Jul 8, 3:01 AM UTC: graphite-app added this pull request to the Graphite merge queue.
  • Jul 8, 3:05 AM UTC: The Graphite merge queue couldn't merge this PR because it had merge conflicts.
  • Jul 9, 2:15 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
  • Jul 9, 2:18 AM UTC: Dunqing added this pull request to the Graphite merge queue.
  • Jul 9, 2:23 AM UTC: Merged by the Graphite merge queue.

@Dunqing
Dunqing force-pushed the om/07-01-perf_minifier_use_replacewith_instead_of_takein_ branch from 865115a to 815a575 Compare July 8, 2026 02:46
@Dunqing
Dunqing force-pushed the graphite-base/24017 branch from e1ad60b to 40f769d Compare July 8, 2026 02:46
@Dunqing
Dunqing changed the base branch from graphite-base/24017 to main July 8, 2026 02:46
@graphite-app graphite-app Bot removed the 0-merge Merge with Graphite Merge Queue label Jul 8, 2026
graphite-app Bot pushed a commit that referenced this pull request Jul 8, 2026
…24292)

## Issue

The `Allocations` CI job can fail on PRs with a 1-allocation `Sys allocs` difference that local `cargo allocs` cannot reproduce. #22621 fixed one instance of this in the transformer stage. #24112 and #24017 hit the same failure again in the minifier stage: `kitchen-sink.tsx` measures 2309 Sys allocs on macOS/arm64 but 2310 on Linux/x64, so whichever platform regenerates the snapshot last breaks CI for the other.

## Why

The tracker counts every call to the system allocator. That includes the chunks bump arenas request. Whether an arena needs one more chunk depends on the total number of bytes in the arena, and byte totals are not the same on every target. For example, hashbrown tables use 16-byte control groups on x86_64 but 8-byte groups on aarch64. When an arena's content size sits close to a chunk boundary, one target crosses it and the other does not.

In the observed failure, the minifier's mangler-phase semantic build creates a fresh `Scoping`. Its arena holds symbol names, resolved-reference vectors, and the per-scope `bindings` hash tables, which are slightly larger on x86_64. The traced Linux-only allocation happened under `Scoping::add_resolved_reference -> ArenaVec::push -> Arena::new_chunk`, when the push overflowed the current chunk and requested a new 720880-byte chunk. On aarch64 the same content fit in the existing chunk, so the count stayed one lower.

Every other allocation class in the measurement grows on element counts, which are identical across platforms. Logging every allocation size during the minifier stage on macOS/arm64, Linux/arm64, and Linux/x64 showed the three sequences match one-to-one except for arena chunk requests.

Any PR that shifts arena content near a chunk boundary can trip this again in any stage, so fixing one stage at a time does not close the class.

## Fix

Count chunk allocations in `oxc_allocator` under the tracker-only `track_allocations` feature, and subtract them from the reported Sys allocs in the tracker. The counter is global rather than per-arena because short-lived arenas (like the one backing `Scoping`) are created and dropped inside the measured operation.

Arena usage is still measured by the `Arena allocs` / `Arena reallocs` columns; only the platform-sensitive chunk-request count is excluded from `Sys allocs`.

Parser and transformer rows are unchanged (the main arena is pre-warmed, and #22621 already removed transformer scoping growth). Semantic, minifier, and formatter rows drop by their per-stage chunk counts.

## Validation

`cargo allocs` produces byte-identical snapshots on macOS/arm64, Linux/arm64 (Docker), and Linux/x64 (Docker), and is idempotent across reruns. `cargo test -p oxc_allocator` passes; clippy is clean with `track_allocations` both on and off, and the counter compiles out entirely without the feature.

AI usage: AI assistance was used to investigate, implement, and validate this change.
@Dunqing

Dunqing commented Jul 9, 2026

Copy link
Copy Markdown
Member

@copilot resolve conflicts

Copilot AI commented Jul 9, 2026

Copy link
Copy Markdown
Contributor

@copilot resolve conflicts

Resolved the conflicts in tasks/track_memory_allocations/allocs_minifier.snap by merging origin/main and regenerating the allocation snapshot to confirm correct values (5f0f02d).

@Dunqing Dunqing added the 0-merge Merge with Graphite Merge Queue label Jul 9, 2026
Replace `take_in` with `replace_with` in as many places as possible in minifier. See #24012 for explanation of the advantage of `replace_with`.

Likely we could use `replace_with` in many more places, if we adapted the methods through which most replacement operations flow (which also track "dirty" state). I've left this for now, as I don't really understand the minifier.
@graphite-app
graphite-app Bot force-pushed the om/07-01-perf_minifier_use_replacewith_instead_of_takein_ branch from 3e70b22 to b227a06 Compare July 9, 2026 02:18
@graphite-app
graphite-app Bot merged commit b227a06 into main Jul 9, 2026
29 checks passed
@graphite-app graphite-app Bot removed the 0-merge Merge with Graphite Merge Queue label Jul 9, 2026
@graphite-app
graphite-app Bot deleted the om/07-01-perf_minifier_use_replacewith_instead_of_takein_ branch July 9, 2026 02:23
Boshen added a commit that referenced this pull request Jul 14, 2026
### 🚀 Features

- 616bfa2 minifier: Remove unreachable code after terminating statements
(#24441) (Dunqing)
- ddab89a data_structures: Add `likely` and `unlikely` functions
(#24368) (overlookmotel)
- a3a39f9 react_compiler: Implement enableEmitHookGuards codegen
(#24329) (Boshen)
- b79eef7 minifier: Apply De Morgan's law to negated comparison chains
in jump guards and loop tests (#24279) (Dunqing)
- 34ff7b4 minifier: Drop write-only property assignments to unused local
bindings by default (#24112) (Dunqing)
- 1b829d8 semantic: Record const enums in EnumData (#24268) (Dunqing)
- ba0944c semantic: Add `Scoping::set_symbol_span` (#24221) (camc314)

### 🐛 Bug Fixes

- 7d33363 minifier: Preserve guaranteed throws from class heritage
evaluation (#24349) (Dunqing)
- 058a62f semantic: Track ambient contexts in `SemanticBuilder` (#24327)
(camc314)
- 721eb0b transformer/decorator: Scope accessor class binding (#24330)
(camc314)
- 1ebdce3 semantic: Allow reserved keywords in ambient declaration types
(#24325) (camc314)
- 460176a track-memory-allocations: Exclude arena chunks from Sys allocs
(#24292) (Dunqing)
- af4922b transformer: Clear lowered namespace redeclarations (#24300)
(camc314)
- ffd2765 semantic: Mark declared computed `MethodDefinition`s as type
references (#24296) (camc314)
- f17514b isolated-declarations: Emit const readonly fields as types
(#24288) (camc314)
- 40f769d minifier: Make `__proto__` write tracking execution-order
independent (#24280) (Dunqing)
- 6371fed transformer: Remove stale enum member bindings (#24272)
(camc314)
- f05dfab transformer: Correct symbol flags for lowered namespaces
(#24271) (Dunqing)
- 84eeb55 transformer: Correct symbol flags for lowered enums (#24269)
(Dunqing)
- c3057da transformer: Preserve generated class binding spans (#24220)
(camc314)
- 8260096 transformer: Correct span for lowered namespace symbol
(#24222) (camc314)
- 42d00d3 semantic: Mark declared class heritage as type references
(#24237) (camc314)
- 588d997 semantic: Mark TS `PropertyDefinition`s computed fields as
type references (#24233) (camc314)
- 9b95632 semantic: Mark computed method keys in `TSMethodSignature`s as
type references (#24232) (camc314)

### ⚡ Performance

- 5b26643 transformer_plugins: Dispatch global defines by trailing name
(#23666) (Boshen)
- dce0f29 react_compiler: Replace all compiled functions in a single AST
walk (#24403) (Boshen)
- f85f0d8 ast: Delegate inherited enum variants in clone_in and estree
derives (#23555) (Boshen)
- 3ff0234 allocator: Remove `unwrap` from `ReplaceWith` (#24365)
(overlookmotel)
- ab22e80 transformer: Fix Rust 1.97 performance regression (#24354)
(camc314)
- b47585c parser: Use `ReplaceWith` instead of `TakeIn` (#24018)
(overlookmotel)
- b227a06 minifier: Use `ReplaceWith` instead of `TakeIn` (#24017)
(overlookmotel)

Co-authored-by: Boshen <[email protected]>
graphite-app Bot pushed a commit to rolldown/rolldown that referenced this pull request Jul 15, 2026
…ue moves (#10285)

## What

Converts the `take_in` → build → write-back patterns in the module finalizer, scan pre-processor, HMR finalizer, and lazy-export generation to `oxc_allocator::ReplaceWith` (available since oxc 0.139) or plain by-value moves.

## Why

Each `take_in` writes a `Dummy` node into the vacated slot; for AST enums that dummy is a real arena allocation (16 bytes boxed) that is overwritten an instant later but stays in the pooled module arena until the generate stage ends. It advances the bump pointer (raising the pool's retained high-water mark) and lowers live-node density for every later walk over the same arena — scanner, DCE, finalizer, codegen. oxc's own parser (oxc-project/oxc#24018) and minifier (oxc-project/oxc#24017) made the same move in 0.140.0.

## How

- **Slot-level `replace_with`**: keep-name wraps (finalizer ×3), both dynamic-`import()`-in-CJS rewrites, the `.then((m) => __toESM(...))` interop wrapper, `replace_first_expr_stmt`, and the PreProcessor's `require(a?b:c)` / `import(a?b:c)` transposes (those destructure the conditional by value — 3 dummies each, now 0).
- **By-value with box reuse**: the finalizer's export-default block and the HMR finalizer's `handle_top_level_stmt` now match the owned statement directly, so `export default function/class` reuses the existing `Box<Function>`/`Box<Class>` instead of take-dummy-rebox (also saves the ~200-byte struct copy). `get_transformed_class_decl` takes the class box by value and returns `Result<Declaration, Box<Class>>`, giving the box back when no transform applies.
- **Plain moves where no trait is needed**: var-hoisting drains `declarations` by value (`Vec`'s dummy is an empty vec — no allocation), JSON prop inlining uses `Option::take`, and paren unwrapping in lazy export works by value.

Left as-is: the `Vec` drain-and-rebuild `take_in`s (free dummy, structurally required) and the `take_in_box` in the dynamic-import-to-other-chunk path, whose `Option`-returning protocol tolerates a partially consumed node on the warn paths.

One behavior note: the finalizer's export-default fallback arm is now `unreachable!()` for `TSInterfaceDeclaration` (TS is stripped before finalization), matching the convention already used by `visit_declaration` and the HMR finalizer for TS variants.

Output is byte-identical: the snapshot suite passes with zero snapshot updates.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

A-minifier Area - Minifier

Projects

None yet

Development

Successfully merging this pull request may close these issues.

4 participants