embedded: fix specialization of associated conformance entries in witness tables #79908
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… in a release-built compiler
…ness tables When creating a specialized witness table, we need to get the right specialized conformance. In IRGen don't emit associated conformance witness table entries if the protocol is not a class protocol. In this case the associated type can never be used to create an existential. Therefore such a witness table entry is never used at runtime in embedded swift. Fixes a compiler crash rdar://146448091
eeckstein
requested review from
rjmccall,
hborla,
slavapestov and
xedin
as code owners
eeckstein
requested review from
kubamracek
and removed request for
xedin,
rjmccall and
hborla
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@swift-ci smoke test |
| @@ -959,6 +959,13 @@ namespace { | |||
| } | |||
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| void addAssociatedConformance(const AssociatedConformance &req) { | |||
| if (req.getAssociation()->getASTContext().LangOpts.hasFeature(Feature::Embedded) && | |||
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It might be better to push this check up to SILWitnessVisitor, which already includes this check for example:
// ObjC protocols do not have witnesses.
if (!Lowering::TypeConverter::protocolRequiresWitnessTable(requirement))
continue;
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This will not work because the FragileWitnessTableBuilder needs to pull the witness table entry before returning.
| @@ -1775,7 +1790,10 @@ class AccessorConformanceInfo : public ConformanceInfo { | |||
| if (IGM.Context.LangOpts.hasFeature(Feature::Embedded)) { | |||
| // In Embedded Swift associated-conformance entries simply point to the witness table | |||
| // of the associated conformance. | |||
| llvm::Constant *witnessEntry = IGM.getAddrOfWitnessTable(associatedConformance.getConcrete()); | |||
| ProtocolConformanceRef assocConf = | |||
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Is it possible for assocConf to differ from associatedConformance above?
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Yes, because ConformanceInContext is not the same as SILWT->getConformance().
(I tried that first and it didn't work).
| @@ -3734,7 +3752,7 @@ llvm::Value *irgen::emitWitnessTableRef(IRGenFunction &IGF, | |||
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| // In Embedded Swift, only class-bound wtables are allowed. | |||
| if (srcType->getASTContext().LangOpts.hasFeature(Feature::Embedded)) { | |||
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IGF.IGM.Context is cleaner IMO
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agreed. I will change it next time I work on this code
When creating a specialized witness table, we need to get the right specialized conformance.
In IRGen don't emit associated conformance witness table entries if the protocol is not a class protocol.
In this case the associated type can never be used to create an existential. Therefore such a witness table entry is never used at runtime in embedded swift.
Fixes a compiler crash
rdar://146448091