[Runtime] Faster dynamic exclusivity checking implemented in Swift. #85624
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mikeash
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Replace C++ implementation of swift_beginAccess and swift_endAccess with (almost) pure Swift implementation. Helpers remain in C++ for TLS, getting return addresses, and raising a fatal error on violations. This change also moves the exclusivity access set head from the shared SwiftTLSContext structure to a dedicated TLS key. This improves performance, which is important for exclusivity checking. This is particularly the case where we can inline TLS access with a constant key, as on Darwin ARM64. The code that bridges exclusivity tracking into Concurrency remains in C++. The new Swift implementation exposes a few helpers for it to use as a replacement for directly manipulating the C++ implementation. rdar://161122309
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@swift-ci please test |
compnerd
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| @@ -0,0 +1,262 @@ | |||
| import SwiftShims | |||
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Replace C++ implementation of swift_beginAccess and swift_endAccess with (almost) pure Swift implementation. Helpers remain in C++ for TLS, getting return addresses, and raising a fatal error on violations.
This change also moves the exclusivity access set head from the shared SwiftTLSContext structure to a dedicated TLS key. This improves performance, which is important for exclusivity checking. This is particularly the case where we can inline TLS access with a constant key, as on Darwin ARM64.
The code that bridges exclusivity tracking into Concurrency remains in C++. The new Swift implementation exposes a few helpers for it to use as a replacement for directly manipulating the C++ implementation. I'd like to move this code into Swift as well, but one thing at a time.
rdar://161122309