Performance tweak for RawXXXSyntax initializers #603
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Avoid cross module generics for now.
`.map { $0.raw }` creates a temporary Array which causes heap
allocations.
Use `RawSyntax.init(kind:unintializedCount:...)` initializer and
directly initialize the storage with the mapped value.
To avoid unnecessary ref-counting traffic.
|
@swift-ci Please test |
ahoppen
reviewed
Aug 18, 2022
| @@ -59,8 +59,15 @@ public struct Raw${node.name}: Raw${node.name if node.is_base() else node.base_t | |||
| % end | |||
| % | |||
| % if node.is_syntax_collection(): | |||
| public init<C: Collection>(elements: C, arena: SyntaxArena) where C.Element == Raw${node.collection_element_type} { | |||
| let raw = RawSyntax.makeLayout(kind: .${node.swift_syntax_kind}, from: elements.map { $0.raw }, arena: arena) | |||
| public init(elements: [Raw${node.collection_element_type}], arena: __shared SyntaxArena) { | |||
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Could we get the same performance improvement by adding
@_specialize(where C == Array<Raw${node.collection_element_type}>)to the declaration while still having the convenience of being able to pass other collections in?
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Probably yes. But it will increase the code size. Since most clients should never use these RawSyntax APIs, I don't think it's worth the bother.
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RawXXXListSyntax.initnow only accepts[Element]instead ofCollection<Element>to avoid potential cross module generics performance issueArraycreation inRawXXXListSyntax.init. Use a low-level initializer and directly initialize the elements buffer__sharedtoarena: SyntaxArenaparameters forRawXXXSyntaxinitializers.