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7989dbe24e
This change adds a new type of cache (cache by type descriptor) to the protocol conformance lookup system. This optimization is beneficial for generic types, where the same conformance can be reused across different instantiations of the generic type. Key changes: - Add a `GetOrInsertManyScope` class to `ConcurrentReadableHashMap` for performing multiple insertions under a single lock - Add type descriptor-based caching for protocol conformances - Add environment variables for controlling and debugging the conformance cache - Add tests to verify the behavior of the conformance cache - Fix for https://github.com/swiftlang/swift/issues/82889 The implementation is controlled by the `SWIFT_DEBUG_ENABLE_CACHE_PROTOCOL_CONFORMANCES_BY_TYPE_DESCRIPTOR` environment variable, which is enabled by default.