refactor(react_compiler): share one AST walk across entrypoint replace visitors#24546
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…e visitors (#24546) Every distinct `Visit`/`VisitMut` implementor monomorphizes the entire generated AST walk; `react_compiler/entrypoint/program.rs` had three such types (`OxcReplaceFnVisitor`, `OxcReplaceWithGatedVisitor`, and the local `Finder`), so the walk was instantiated three times. They are now a single `OxcVisitor` selected by an `OxcVisitMode` enum (`ReplaceFns` / `ReplaceWithGated` / `FindOriginalFn`), so the walk is instantiated once. Each overridden method dispatches on the mode and behaves exactly like the default walk in the modes that do not use it, preserving traversal order and the early-exit semantics (`remaining == 0`, `done`, `found.is_some()`). `Finder` moves from the read-only `VisitJs` walk onto the shared `VisitMut` walk — a superset traversal; it matches a unique `scope_id`, and function scopes cannot occur in the pruned type grammar (per #24532), so the lookup result is unchanged. The Babel-mirroring notes (`ReplaceFnVisitor` / `ReplaceWithGatedVisitor`) stay on the corresponding modes, and the per-node replacement logic is ported verbatim into free helpers (`ox_replace_function`, `ox_replace_arrow`, `ox_build_gated_const_decl`). Measured on this crate's release example binary (`--example react_compiler`, workspace release profile with fat LTO): machine code (`__text`) shrinks by 24,112 bytes (~24 KB), file size by 16,592 bytes (~17 KB). The three walk instantiations measured ~34K/~16K/~14K in the symbol-level size analysis of the release napi binary that motivated this change. Behavior is verified unchanged on the full fixture snapshot corpus (1,736 snapshots, including the `gating__*` fixtures that exercise the gated-replacement and original-function-lookup paths), and the release example binary produces byte-identical output before and after across the gating and general fixtures. Authored with Claude Code; reviewed by a human before merge.
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Every distinct
Visit/VisitMutimplementor monomorphizes the entire generated AST walk;react_compiler/entrypoint/program.rshad three such types (OxcReplaceFnVisitor,OxcReplaceWithGatedVisitor, and the localFinder), so the walk was instantiated three times. They are now a singleOxcVisitorselected by anOxcVisitModeenum (ReplaceFns/ReplaceWithGated/FindOriginalFn), so the walk is instantiated once.Each overridden method dispatches on the mode and behaves exactly like the default walk in the modes that do not use it, preserving traversal order and the early-exit semantics (
remaining == 0,done,found.is_some()).Findermoves from the read-onlyVisitJswalk onto the sharedVisitMutwalk — a superset traversal; it matches a uniquescope_id, and function scopes cannot occur in the pruned type grammar (per #24532), so the lookup result is unchanged. The Babel-mirroring notes (ReplaceFnVisitor/ReplaceWithGatedVisitor) stay on the corresponding modes, and the per-node replacement logic is ported verbatim into free helpers (ox_replace_function,ox_replace_arrow,ox_build_gated_const_decl).Measured on this crate's release example binary (
--example react_compiler, workspace release profile with fat LTO): machine code (__text) shrinks by 24,112 bytes (~24 KB), file size by 16,592 bytes (~17 KB). The three walk instantiations measured ~34K/~16K/~14K in the symbol-level size analysis of the release napi binary that motivated this change.Behavior is verified unchanged on the full fixture snapshot corpus (1,736 snapshots, including the
gating__*fixtures that exercise the gated-replacement and original-function-lookup paths), and the release example binary produces byte-identical output before and after across the gating and general fixtures.Authored with Claude Code; reviewed by a human before merge.