Skip leading trivia generation if empty in BuildableNodes #639
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fwcd
commented
Aug 25, 2022
Comment on lines
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| IfStmt( | ||
| conditions: ExprList([MemberAccessExpr(base: "combinedLeadingTrivia", name: "isEmpty")]) | ||
| ) { | ||
| ReturnStmt(expression: "result") | ||
| } elseBody: { | ||
| ReturnStmt(expression: FunctionCallExpr(MemberAccessExpr(base: "result", name: "withLeadingTrivia")) { | ||
| TupleExprElement(expression: FunctionCallExpr(MemberAccessExpr( | ||
| base: "combinedLeadingTrivia", | ||
| name: "addingSpacingAfterNewlinesIfNeeded" | ||
| ))) | ||
| }) | ||
| } |
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One idea might be to move this logic into withLeadingTrivia itself (and similarly into withTrailingTrivia). However since we cannot assume that the syntax doesn't already have trivia (like in this case) the check would likely get more expensive, so I am not sure whether the more general solution would be worth it there.
|
@swift-ci please test |
ahoppen
approved these changes
Aug 25, 2022
|
@swift-ci please test macOS |
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Although we discussed this earlier, I would like to revisit the optimization to skip leading trivia generation on buildable nodes in
SwiftSyntaxBuilderwhen empty, since it actually does have a noticeable performance impact ongenerate-swift-syntax-builder: The optimization cuts down generation time from ~13 seconds to ~7 seconds on my machine, nearly a 50% improvement in performance! Profiling the executable with Instruments reveals that this indeed seems to be the issue, the heaviest stack trace points towithLeadingTrivia.The improvement in performance with this patch becomes especially noticeable during development of generated files where shorter feedback cycles greatly improve the workflow.
(This change should be mostly orthogonal to the upcoming formatting-related changes)