Introduce PublicNonABI linkage for default argument generators and stored property initializers #13934
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@aschwaighofer @eeckstein @airspeedswift This can be used to implement "always emit into client" semantics for ordinary functions as well, either @_transparent (as Arnold and Erik proposed) or a new secret attribute for use in the stdlib (Ben's request). |
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@swift-ci Please smoke test |
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@swift-ci Please test source compatibility |
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@swift-ci Please test source compatibility |
This is going to be used for "always emit into client" functions, such as default argument generators and stored property initializers. - In dead function elimination, these functions behave identically to public functions, serving as "anchors" for the mark-and-sweep analysis. - There is no external variant of this linkage, because external declarations can use HiddenExternal linkage -- the definition should always be emitted by another translation unit in the same Swift module. - When deserialized, they receive shared linkage, because we want the linker to coalesce multiple copies of the same deserialized definition if it was deserialized from multiple translation units in the same Swift module. - When IRGen emits a definition with this linkage, it receives the same LLVM-level linkage as a hidden definition, ensuring it does not have a public entry point.
Previously we were creating private [serialized] functions here, which do not deserialize properly. This was only exposed by making default argument generators PublicNonABI also.
…t 4 mode Fixes <rdar://problem/33767513>, <https://bugs.swift.org/browse/SR-5647>.
Also, bail out before emitting any default argument generators in Swift 4 mode. This is NFC, because we already check the linkage of the SILDeclRef and skip it if its not public. But adding the check explicitly here serves as a reminder that this entire code block can be deleted if we ever decide to kill off Swift 3 compatibility.
…ixed_layout types Fixes <rdar://problem/36429556>.
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swiftlang/swift-corelibs-foundation#1394 |
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Fixes rdar://problem/36429556, rdar://problem/33767513, https://bugs.swift.org/browse/SR-5647.