Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

perf(transformer/arrow-functions): bail out of visiting early when inserting _this = this after super() #8482

Conversation

overlookmotel
Copy link
Contributor

@overlookmotel overlookmotel commented Jan 14, 2025

In arrow functions transform (including async-to-generator), we need to insert a _this = this assignment in parent function, if the arrow function uses this. If the arrow function is in constructor of a class which extends another class, this assignment needs to be inserted after super(), because this is invalid before a super() call has occurred.

Optimize the visitor which searches class constructor for super() for the common case where super() call occurs as a top-level statement early in the constructor. e.g.

class C extends S {
    constructor() {
        super();
        // ... lots more code here ...
    }
}

In this case, we can insert _this = this; statement after super(); and then exit the visitor. There's no need search the rest of the constructor for further super() calls, because _this is definitely now initialized prior to any of that code.

@github-actions github-actions bot added A-transformer Area - Transformer / Transpiler C-performance Category - Solution not expected to change functional behavior, only performance labels Jan 14, 2025
Copy link
Contributor 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 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.

@overlookmotel overlookmotel marked this pull request as ready for review January 14, 2025 09:49
Copy link

codspeed-hq bot commented Jan 14, 2025

CodSpeed Performance Report

Merging #8482 will not alter performance

Comparing 01-13-perf_transformer_arrow-functions_bail_out_of_visiting_early_when_inserting__this_this_after_super_ (53ef263) with main (3e05055)

Summary

✅ 32 untouched benchmarks

Copy link
Member

@Dunqing Dunqing left a comment

Choose a reason for hiding this comment

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

That's an interesting improvement!

@Dunqing Dunqing added the 0-merge Merge with Graphite Merge Queue label Jan 14, 2025
Copy link
Member

Dunqing commented Jan 14, 2025

Merge activity

  • Jan 14, 8:09 AM EST: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
  • Jan 14, 8:09 AM EST: A user added this pull request to the Graphite merge queue.
  • Jan 14, 8:14 AM EST: A user merged this pull request with the Graphite merge queue.

Partially verified

This commit was created on GitHub.com and signed with GitHub’s verified signature. The key has expired.
We cannot verify signatures from co-authors, and some of the co-authors attributed to this commit require their commits to be signed.
…serting `_this = this` after `super()` (#8482)

In arrow functions transform (including async-to-generator), we need to insert a `_this = this` assignment in parent function, if the arrow function uses `this`. If the arrow function is in constructor of a class which `extend`s another class, this assignment needs to be inserted after `super()`, because `this` is invalid before a `super()` call has occurred.

Optimize the visitor which searches class constructor for `super()` for the common case where `super()` call occurs as a top-level statement early in the constructor. e.g.

```js
class C extends S {
    constructor() {
        super();
        // ... lots more code here ...
    }
}
```

In this case, we can insert `_this = this;` statement after `super();` and then exit the visitor. There's no need search the rest of the constructor for further `super()` calls, because `_this` is definitely now initialized prior to any of that code.
@Dunqing Dunqing force-pushed the 01-13-perf_transformer_arrow-functions_bail_out_of_visiting_early_when_inserting__this_this_after_super_ branch from 16a8343 to 53ef263 Compare January 14, 2025 13:10
@graphite-app graphite-app bot merged commit 53ef263 into main Jan 14, 2025
25 checks passed
@graphite-app graphite-app bot deleted the 01-13-perf_transformer_arrow-functions_bail_out_of_visiting_early_when_inserting__this_this_after_super_ branch January 14, 2025 13:14
Dunqing pushed a commit that referenced this pull request Jan 15, 2025
…8494)

Follow-on after #8482.

Fix an edge case in arrow functions transform when inserting `_this = this` after `super()`. It is possible (though bizarre) for `super()` to contain another `super()` call. This will throw an error when evaluating the outer `super()`, but it can still be observable in some cases.

```js
let f;
class S {}
class C extends S {
  constructor(x) {
    super(super(), this.x = x, f = async () => this);
  }
}

try { new C(123) } catch {}

const c = await f();
assert(c.x === 123);
```

So, before bailing out from searching for more `super()`s in class constructor, visit the `super()` call's arguments.
Boshen added a commit that referenced this pull request Jan 18, 2025
## [0.47.0] - 2025-01-18

- fae4cd2 allocator: [**BREAKING**] Remove `Vec::into_string` (#8571)
(overlookmotel)

- 95bc0d7 allocator: [**BREAKING**] `Allocator` do not deref to
`bumpalo::Bump` (#8569) (overlookmotel)

- 19d3677 ast: [**BREAKING**] Always return
`Array<ImportDeclarationSpecifier>` for `ImportDeclaration.specifiers`
(#8560) (sapphi-red)

- 4ce6329 semantic: [**BREAKING**] Ensure program outlives semantic
(#8455) (Valentinas Janeiko)

- 7066d1c ast, span, syntax, regular_expression: [**BREAKING**] Remove
`ContentHash` (#8512) (overlookmotel)

### Features

- bf4e5e1 allocator: Add `HashMap` (#8553) (overlookmotel)
- a6d71f8 ast: Add `AstKind::ty` method (#8521) (overlookmotel)
- 4d4e805 minifier: Collapse if stmt with empty consequent (#8577)
(camc314)
- 991a22f minifier: Fold `Array::concat` into literal (#8442)
(sapphi-red)
- 3dc2d8b minifier: Fold string concat chaining (#8441) (sapphi-red)
- a4ae450 minifier: Fold array concat chaining (#8440) (sapphi-red)
- 7cc81ef minifier: Fold invalid typeof comparisons (#8550) (camc314)
- 927f43f minifier: Improve `.charCodeAt(arg)` when arg is valid (#8534)
(Boshen)
- 06f14d5 minifier: Remove empty class static block `class Foo { static
{} }` (#8525) (Boshen)
- 1860411 minifier: Remove last redundant return statement (#8523)
(Boshen)
- c479a58 napi/parser: Expose dynamic import expressions (#8540)
(Boshen)
- 2f0314e npm/oxc-minify: Npm package and publish script (#8579)
(Boshen)
- f413bb5 transformer/optional-chaining: Change parent scope for
expression when it wrapped with an arrow function (#8511) (Dunqing)

### Bug Fixes

- e87c001 allocator: Statically prevent memory leaks in allocator
(#8570) (overlookmotel)
- 855c839 codegen: Shorthand assignment target identifier consider
mangled names (#8536) (Boshen)
- 65c596d minifer: Keep idents if not in scope when minimizing array
exprs (#8551) (camc314)
- f57aac2 minifier: Incorrect folding of expr in bool ctx (#8542)
(camc314)
- 946ad76 minifier: `(-Infinity).toString()` -> `'-Infinity'` (#8535)
(Boshen)
- b1d0186 minifier: Do not fold `!!void b` (#8533) (Boshen)
- 53adde5 minifier: `x['-2147483648']` -> `x[-2147483648]` (#8528)
(Boshen)
- 405b73d minifier: Do not change `delete undefined` to `delete void 0`
(#8527) (Boshen)
- 92e44cb minifier: Do not remove `undefined` in `var x = undefined`
(#8526) (Boshen)
- 209e313 minifier: `class C { ['-1']() {} }` cannot be minifized
(#8516) (Boshen)
- 6585463 minifier: Always keep the last value of sequence expression
(#8490) (Boshen)
- b552f5c transformer: `wrap_in_arrow_function_iife` take span of input
`Expression` (#8547) (overlookmotel)
- 9963533 transformer/arrow-functions: Visit arguments to `super()` call
(#8494) (overlookmotel)
- 06ccb51 transformer/async-to-generator: Move parameters to the inner
generator function when they could throw errors (#8500) (Dunqing)
- 356f0c1 transformer/class-properties: Handle nested `super()` calls
(#8506) (overlookmotel)
- a048337 transformer/class-static-blocks: Static block converted to
IIFE use span of original block (#8549) (overlookmotel)

### Performance

- 76ea52b allocator: Inline `Box` methods (#8572) (overlookmotel)
- 93df57f allocator: `#[inline(always)]` methods of `Vec` which just
delegate to `allocator_api2` (#8567) (overlookmotel)
- 5a28d68 allocator: `#[inline(always)]` methods of `HashMap` which just
delegate to `hashbrown` (#8565) (overlookmotel)
- d17021c mangler: Optimize `base54` function (#8557) (overlookmotel)
- 6b52d7a mangler: Use a single allocation space for temporary vecs
(#8495) (Boshen)
- 30a869e semantic: Use `oxc_allocator::HashMap` in `ScopeTree` (#8554)
(overlookmotel)
- 63eb298 span: Compare `Span`s as single `u64`s (#8300) (overlookmotel)
- a43560c span: Hash `Span` as a single `u64` (#8299) (overlookmotel)
- 3fff7d2 span: Align `Span` same as `usize` (#8298) (overlookmotel)
- 53ef263 transformer/arrow-functions: Bail out of visiting early when
inserting `_this = this` after `super()` (#8482) (overlookmotel)

### Documentation

- fa1a6d5 allocator: Update docs for `Vec` (#8555) (overlookmotel)

### Refactor

- ac05134 allocator: `String` type (#8568) (overlookmotel)
- 68fab81 allocator: Rename inner `Vec` type (#8566) (overlookmotel)
- fcbca32 ast: Rename `#[estree(with)]` to `#[estree(via)]` (#8564)
(overlookmotel)
- 007e8c0 ast, regular_expression: Shorten `ContentEq` implementations
(#8519) (overlookmotel)
- b4c87e2 linter: Move DiagnosticsReporters to oxlint (#8454) (Alexander
S.)
- 8f57929 minifier: Merge `try_compress_type_of_equal_string` into
`try_minimize_binary` (#8561) (sapphi-red)
- 2857ae1 parser: Refactor visitor in regexp example (#8524)
(overlookmotel)
- b5ed58e span: All methods take owned `Span` (#8297) (overlookmotel)
- 712633f transformer: `wrap_statements_in_arrow_function_iife` utility
function (#8548) (overlookmotel)
- 5206c6a transformer: Rename `wrap_in_arrow_function_iife` (#8546)
(overlookmotel)
- 61077ca transformer: `wrap_arrow_function_iife` receive an owned
`Expression` (#8545) (overlookmotel)
- 6820d24 transformer: Move `wrap_arrow_function_iife` to root utils
module (#8529) (Dunqing)
- 52bd0b1 transformer: Move common utils functions to the root module
(#8513) (Dunqing)
- c30654a transformer/arrow-function: Wrapping arrow function iife by
using `wrap_arrow_function_iife` (#8530) (Dunqing)
- 2bc5175 transformer/arrow-functions: Rename method (#8481)
(overlookmotel)
- 72f425f transformer/class-properties: Fix lint warning in release mode
(#8539) (overlookmotel)
- 7e61b23 transformer/typescript: Shorten code (#8504) (overlookmotel)
- 04bc259 traverse: Remove unnecessary `#[allow]` (#8518)
(overlookmotel)
- a368726 traverse: Harden soundness of `Traverse` and document safety
invariants better (#8507) (overlookmotel)

### Testing

- e0f5d6c minifier: Update esbuild test (Boshen)
- 629c417 minifier: Port esbuild minification tests (#8497) (Boshen)

Co-authored-by: Boshen <[email protected]>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
0-merge Merge with Graphite Merge Queue A-transformer Area - Transformer / Transpiler C-performance Category - Solution not expected to change functional behavior, only performance
Projects
None yet
Development

Successfully merging this pull request may close these issues.

None yet

2 participants