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Account for -disable-preallocated-instantiation-caches for non-dependent wtables in swift_getWitnessTable #41199

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Merged
merged 1 commit into from
Feb 4, 2022
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Account for -disable-preallocated-instantiation-caches for non-dependent wtables in swift_getWitnessTable #41199

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6 changes: 4 additions & 2 deletions include/swift/ABI/Metadata.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2462,7 +2462,8 @@ struct TargetGenericWitnessTable {
using PrivateDataType = void *[swift::NumGenericMetadataPrivateDataWords];

/// Private data for the instantiator. Out-of-line so that the rest
/// of this structure can be constant.
/// of this structure can be constant. Might be null when building with
/// -disable-preallocated-instantiation-caches.
RelativeDirectPointer<PrivateDataType> PrivateData;

uint16_t getWitnessTablePrivateSizeInWords() const {
Expand Down Expand Up @@ -3536,7 +3537,8 @@ using OpaqueTypeDescriptor = TargetOpaqueTypeDescriptor<InProcess>;
template <typename Runtime>
struct TargetGenericMetadataInstantiationCache {
/// Data that the runtime can use for its own purposes. It is guaranteed
/// to be zero-filled by the compiler.
/// to be zero-filled by the compiler. Might be null when building with
/// -disable-preallocated-instantiation-caches.
TargetPointer<Runtime, void>
PrivateData[swift::NumGenericMetadataPrivateDataWords];
};
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5 changes: 4 additions & 1 deletion stdlib/public/runtime/Metadata.cpp
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Expand Up @@ -4999,6 +4999,8 @@ WitnessTableCacheEntry::allocate(
static WitnessTable *
getNondependentWitnessTable(const ProtocolConformanceDescriptor *conformance,
const Metadata *type) {
assert(conformance->getGenericWitnessTable()->PrivateData != nullptr);

// Check whether the table has already been instantiated.
auto tablePtr = reinterpret_cast<std::atomic<WitnessTable*> *>(
conformance->getGenericWitnessTable()->PrivateData.get());
Expand Down Expand Up @@ -5065,7 +5067,8 @@ swift::swift_getWitnessTable(const ProtocolConformanceDescriptor *conformance,
// least, not today). However, a generic type conformance may also be
// nondependent if it
auto typeDescription = conformance->getTypeDescriptor();
if (typeDescription && !typeDescription->isGeneric()) {
if (typeDescription && !typeDescription->isGeneric() &&
genericTable->PrivateData != nullptr) {
return getNondependentWitnessTable(conformance, type);
}

Expand Down