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KeyPath's getter/setter/hash/equals functions have their own calling convention, which receives generic arguments and embedded indices from a given KeyPath argument buffer. The convention was previously implemented by: 1. Accepting an argument buffer as an UnsafeRawPointer and casting it to indices tuple pointer in SIL. 2. Bind generic arguments info from the given argument buffer while emitting prologue in IRGen by creating a new forwarding thunk. This 2-phase lowering approach was not ideal, as it blocked KeyPath projection optimization [^1], and also required having a target arch specific signature lowering logic in SIL-level [^2]. This patch centralizes the KeyPath accessor calling convention logic to IRGen, by introducing `@convention(keypath_accessor_XXX)` convention in SIL and lowering it in IRGen. This change unblocks the KeyPath projection optimization while capturing subscript indices, and also makes it easier to support WebAssembly target. [^1]: https://github.com/apple/swift/pull/28799 [^2]: https://forums.swift.org/t/wasm-support/16087/21
19 lines
541 B
Swift
19 lines
541 B
Swift
// RUN: %target-swift-frontend -g -emit-ir %s | %FileCheck %s
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public struct Gen<Value> {
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public private(set) var value: Value
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public func use<Subject>(keyPath: WritableKeyPath<Value, Subject>) {
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}
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}
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// This used to assert.
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// CHECK: distinct !DISubprogram(linkageName: "$sSly7ElementQz5IndexQzcipSMRzSHADRQlxxTK", {{.*}} flags: DIFlagArtificial
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extension Gen where Value : MutableCollection, Value.Index : Hashable {
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public var dontAssert: Int {
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var i = value.startIndex
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use(keyPath: \.[i])
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return 0
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}
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}
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