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[6.2] Relative witness table fixes #80845

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Merged
merged 3 commits into from
Apr 17, 2025
Merged

[6.2] Relative witness table fixes #80845

merged 3 commits into from
Apr 17, 2025

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DougGregor
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@DougGregor DougGregor commented Apr 16, 2025 •
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@DougGregor
[Runtime] Handle relative witness tables in _getIsolationCheckingOpti…
2de64b6 
…onsFromExecutorWitnessTable

Part of rdar://148687148.
@DougGregor
[Runtime] Don't use the low bit of a WitnessTable pointer in the conf…
e32174a 
…ormance cache

With relative witness tables, the low bit of a witness table pointer is
an indicator that we need to load from the given pointer. We were also
using the low bit of the witness table pointer in the conformance
cache entry as part of a pointer union. Hilarity ensures [*].

Switch to another low bit by exploding the conformance cache key
into separate fields and taking the low bit of one of those pointers
that isn't reserved.

Fixes the remainder of rdar://149326058, I hope.

[*] No, I am not laughing.
@DougGregor DougGregor requested a review from a team as a code owner April 16, 2025 01:19
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@swift-ci please test

@DougGregor
[Conformance cache] Handle missing protocol descriptors
77caa2d 
This can happen when running against an older version of a library that
doesn't have the protocol defined.
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@swift-ci please test

@DougGregor DougGregor merged commit 15ecd66 into swiftlang:release/6.2 Apr 17, 2025
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@DougGregor DougGregor deleted the relative-witness-tables-fixes-6.2 branch April 17, 2025 00:37
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