[AutoDiff] Use LinkEntity::SecondaryPointer for diff witness
#82412
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If `LinkEntity::isTypeKind()` is true, `IRGenModule::getAddrOfLLVMVariable` assumes that we can safely call `LinkEntity::getType()`, which does `reinterpret_cast` of `LinkEntity::Pointer` to `TypeBase *`. However, for SIL differentiability witness, the pointer has `SILDifferentiabilityWitness *` type, which is not derived from `TypeBase`. So, such a cast is not allowed. Just as with `ProtocolWitnessTableLazyAccessFunction` and `ProtocolWitnessTableLazyCacheVariable` link entity kinds (which are also type kinds), we should use `SecondaryPointer` instead of `Pointer` for storing payload here, while setting `Pointer` to `nullptr`.
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@swift-ci please test |
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Tagging @JaapWijnen |
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This kind of problem seems to be easily spotted by ASAN. Likely we'd need to use |
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If
LinkEntity::isTypeKind()is true,IRGenModule::getAddrOfLLVMVariableassumes that we can safely callLinkEntity::getType(), which doesreinterpret_castofLinkEntity::PointertoTypeBase *. However, for SIL differentiability witness, the pointer hasSILDifferentiabilityWitness *type, which is not derived fromTypeBase. So, such a cast is not allowed.Just as with
ProtocolWitnessTableLazyAccessFunctionandProtocolWitnessTableLazyCacheVariablelink entity kinds (which are also type kinds), we should useSecondaryPointerinstead ofPointerfor storing payload here, while settingPointertonullptr.