perf(transformer): allocate AST nodes in arena directly

[overlookmotel]

Same as #23709.

Small perf optimizations around AST builder calls.

• AST nodes which end up in Boxes, allocate into the Box as early as possible, to increase chance compiler sees the type can be built directly in arena, rather than built on the stack, and then copied from stack into arena.
• Functions return Box<T> rather than T where the value needs to be boxed anyway. If function is not inlined, this avoids stack allocation + copy.

Also, shorten code where possible by using more specific AstBuilder methods.

In transform_ts_import_equals, additionally avoid unnecessarily allocating the string "require" into arena, by using static_ident! instead.

[overlookmotel]

• refactor(parser): switch parser to new AstBuilder #23730
• feat(ast): add methods to create primitives to new AstBuilder #23729
• feat(ast): add custom builder methods to AST types #23651
• feat(ast): add AST creation methods to AST types #23650
• refactor(ast): add ast_builder Cargo feature #23649
• perf(transformer/object-rest-spread): reduce iteration #23720
• perf(transformer): allocate AST nodes in arena directly #23711 👈 (View in Graphite)
• perf(parser): allocate AST nodes in arena directly #23712
• perf(minifier): allocate AST nodes in arena directly #23710
• perf(isolated_declarations): allocate AST nodes in arena directly #23709
• refactor(ast): remove AstBuilder::alloc calls #23708
• main

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[codspeed-hq]

Merging this PR will not alter performance

✅ 52 untouched benchmarks
⏩ 19 skipped benchmarks¹

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_{Comparing om/06-21-perf_transformer_allocate_ast_nodes_in_arena_directly (55fd31d) with om/06-21-perf_parser_allocate_ast_nodes_in_arena_directly (b57ac10)²}

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. ↩

2. No successful run was found on om/06-21-perf_parser_allocate_ast_nodes_in_arena_directly (0090ac3) during the generation of this report, so ea62bb9 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 applies small, mechanical performance optimizations across the transformer by allocating AST nodes directly into the arena (especially where nodes are immediately boxed), reducing temporary stack allocations/copies, and using more specific AstBuilder helpers.

Changes:

• Prefer alloc_*/boxed-returning builder APIs and pass ArenaBox values through directly to avoid extra ctx.alloc(...) + moves.
• Update helper construction (helper_call) and several transforms to return/consume boxed nodes where boxing is inevitable.
• Avoid allocating "require" into the arena by using static_ident! in TS import-equals lowering.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tasks/track_memory_allocations/allocs_transformer.snap	Updates allocation snapshot to reflect the new arena-allocation behavior.
crates/oxc_transformer/src/typescript/module.rs	Uses static_ident! for require, allocates string literal args directly in arena, and builds identifier expressions without clone+alloc.
crates/oxc_transformer/src/typescript/enum.rs	Builds enum binding patterns directly with symbol id (avoids clone+alloc path).
crates/oxc_transformer/src/typescript/annotations.rs	Allocates identifier references directly into the arena and passes boxed identifiers through.
crates/oxc_transformer/src/jsx/jsx_impl.rs	Returns ArenaBox<IdentifierReference> from internal helpers and avoids repeated allocate-then-wrap patterns.
crates/oxc_transformer/src/es2021/logical_assignment_operators.rs	Builds identifier expressions directly with known reference_id instead of cloning + arena allocation.
crates/oxc_transformer/src/es2018/object_rest_spread.rs	Adjusts helper call usage and variable declaration creation to operate on boxed arena nodes end-to-end.
crates/oxc_transformer/src/decorator/legacy/mod.rs	Clones literal/template data directly into the allocator to avoid intermediate allocations.
crates/oxc_transformer/src/common/var_declarations.rs	Uses dedicated binding-pattern builder helpers to avoid extra allocation steps.
crates/oxc_transformer/src/common/helper_loader.rs	Changes helper_call to return ArenaBox<CallExpression> and allocates the call expression directly in the arena.
crates/oxc_transformer_plugins/src/module_runner_transform.rs	Allocates reused binding identifiers into the arena earlier and constructs string literal arguments more directly.

[graphite-app]

Merge activity

• Jun 23, 12:59 AM UTC: overlookmotel added this pull request to the Graphite merge queue.
• Jun 23, 1:07 AM UTC: Merged by the Graphite merge queue.