[Sema] Stop visiting existential exprs an extra time checking for uses #27150
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This was causing an exponential amount of time traversing the AST with deeply chained protocol extension methods, such as in the TestCodableRouter.swift test in Kitura. If the OpaqueValueExpr is referenced more than once within the OpenExistentialExpr it'll still get visited more than once, but that doesn't seem to happen in practice. If it turns out to be a problem, we can weaken the assertion I'm adding here. https://bugs.swift.org/browse/SR-11012
Is this actually a valid assumption, reviewerfolk? |
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@swift-ci Please test |
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@swift-ci Please test source compatibility |
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Nice catch. Currently an OVE can only be referenced once regardless of its parent expr. This is enforced with assertions in SILGen. |
slavapestov
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Sep 13, 2019
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apple#27150) This was causing an exponential amount of time traversing the AST with deeply chained protocol extension methods, such as in the TestCodableRouter.swift test in Kitura. If the OpaqueValueExpr is referenced more than once within the OpenExistentialExpr it'll still get visited more than once, but that doesn't seem to happen in practice. If it turns out to be a problem, we can weaken the assertion I'm adding here. https://bugs.swift.org/browse/SR-11012 (cherry picked from commit dc59cd2)
jrose-apple
added a commit
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that referenced
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Sep 13, 2019
apple#27150) This was causing an exponential amount of time traversing the AST with deeply chained protocol extension methods, such as in the TestCodableRouter.swift test in Kitura. If the OpaqueValueExpr is referenced more than once within the OpenExistentialExpr it'll still get visited more than once, but that doesn't seem to happen in practice. If it turns out to be a problem, we can weaken the assertion I'm adding here. https://bugs.swift.org/browse/SR-11012 (cherry picked from commit dc59cd2)
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This was causing an exponential amount of time traversing the AST with deeply chained protocol extension methods, such as in the TestCodableRouter.swift test in Kitura. Introduced in #23867.
If the OpaqueValueExpr is referenced more than once within the OpenExistentialExpr it'll still get visited more than once, but that doesn't seem to happen in practice. If it turns out to be a problem, we can weaken the assertion I'm adding here.
SR-11012 / rdar://problem/52194425