Give more extra inhabitants to BridgeObject. #20416
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@swift-ci Please test |
| @@ -167,5 +190,10 @@ tests.test("types that have extra inhabitants") { | |||
| expectHasExtraInhabitant(GenericFullHouse<UnsafeRawPointer, UnsafeRawPointer>.self, nil: nil) | |||
| } | |||
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| tests.test("types that have more than one extra inhabitant") { | |||
| expectHasAtLeastThreeExtraInhabitants(StringAlike64.self, nil: nil, someNil: .some(nil), someSomeNil: .some(.some(nil))) | |||
| expectHasAtLeastThreeExtraInhabitants(StringAlike32.self, nil: nil, someNil: .some(nil), someSomeNil: .some(.some(nil))) | |||
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It's probably also worth checking that a non-nil object doesn't have the same representation as any of the nils. In particular, _bridgeObject(taggingPayload: 0) and _bridgeObject(taggingPayload: 1) are probably worth checking.
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@swift-ci Please smoke test Linux |
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jckarter
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The standard library never ended up needing the low extra inhabitants (<4G on 64-bit Darwin, <4K elsewhere), so BridgeObject can have the same set of extra inhabitants as the other refcounted types, allowing `String?????` and `Array??????????` to still use optimized representations. rdar://problem/45881464
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@swift-ci Please smoke test |
| // There's only one extra inhabitant, 0. | ||
| dest = IGF.Builder.CreateBitCast(dest, IGF.IGM.SizeTy->getPointerTo()); | ||
| IGF.Builder.CreateStore(llvm::ConstantInt::get(IGF.IGM.SizeTy, 0), dest); | ||
| } |
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Okay, I understand why this works. As long as we're staying out of the reserved bits for tagged pointers (including BridgeObject's own notion of tagged pointers) — which the superclass implementation does — it doesn't matter if we're intruding on the BridgeObject representation because the rest of the pointer still needs to be in the valid range for objects.
The standard library never ended up needing the low extra inhabitants (<4G on 64-bit Darwin,
<4K elsewhere), so BridgeObject can have the same set of extra inhabitants as the other refcounted
types, allowing
String?????andArray??????????to still use optimized representations.rdar://problem/45881464