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5a6d2dfa59
In anticipation of potential future HW features, e.g. armv8.5 memory tagging, only use the high 4 bytes as discriminator bits in _BridgeObject rather than the top 8 bits. Utilize two perf flags to cover this instead. This requires shifting around a fair amount of internal complexity.
77 lines
2.1 KiB
Swift
77 lines
2.1 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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// Declarations to enable ease-of-testing
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public // @testable
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struct _StringRepresentation {
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public var _isASCII: Bool
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public var _count: Int
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public var _capacity: Int
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public enum _Form {
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case _small
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case _cocoa(object: AnyObject)
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case _native(object: AnyObject)
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case _immortal(address: UInt)
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// TODO: shared native
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}
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public var _form: _Form
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public var _objectIdentifier: ObjectIdentifier? {
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switch _form {
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case ._cocoa(let object): return ObjectIdentifier(object)
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case ._native(let object): return ObjectIdentifier(object)
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default: return nil
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}
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}
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}
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extension String {
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public // @testable
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func _classify() -> _StringRepresentation { return _guts._classify() }
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}
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extension _StringGuts {
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internal func _classify() -> _StringRepresentation {
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var result = _StringRepresentation(
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_isASCII: self.isASCII,
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_count: self.count,
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_capacity: nativeCapacity ?? 0,
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_form: ._small
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)
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if self.isSmall {
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result._capacity = _SmallString.capacity
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return result
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}
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if _object.largeIsCocoa {
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result._form = ._cocoa(object: _object.cocoaObject)
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return result
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}
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// TODO: shared native
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_internalInvariant(_object.providesFastUTF8)
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if _object.isImmortal {
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result._form = ._immortal(
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address: UInt(bitPattern: _object.nativeUTF8Start))
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return result
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}
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if _object.hasNativeStorage {
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_internalInvariant(_object.largeFastIsTailAllocated)
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result._form = ._native(object: _object.nativeStorage)
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return result
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}
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fatalError()
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}
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}
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