Merge pull request swiftlang#33497 from nate-chandler/generic-metadata-prespecialization-components/replace-erase-with-early-return

Author: swift-ci

lib/IRGen/GenDecl.cpp

@@ -1168,6 +1168,7 @@ static void
 deleteAndReenqueueForEmissionValuesDependentOnCanonicalPrespecializedMetadataRecords(
     IRGenModule &IGM, CanType typeWithCanonicalMetadataPrespecialization,
     NominalTypeDecl &decl) {
+  IGM.IRGen.noteLazyReemissionOfNominalTypeDescriptor(&decl);
   // The type context descriptor depends on canonical metadata records because
   // pointers to them are attached as trailing objects to it.
   //

lib/IRGen/GenMeta.cpp

@@ -301,10 +301,12 @@ static void buildMethodDescriptorFields(IRGenModule &IGM,
 void IRGenModule::emitNonoverriddenMethodDescriptor(const SILVTable *VTable,
                                                     SILDeclRef declRef) {
   auto entity = LinkEntity::forMethodDescriptor(declRef);
-
   auto *var = cast<llvm::GlobalVariable>(getAddrOfLLVMVariable(entity, ConstantInit(), DebugTypeInfo()));
-  var->setInitializer(nullptr);
- 
+  if (!var->isDeclaration()) {
+    assert(IRGen.isLazilyReemittingNominalTypeDescriptor(VTable->getClass()));
+    return;
+  }
+
   ConstantInitBuilder ib(*this);
   ConstantStructBuilder sb(ib.beginStruct(MethodDescriptorStructTy));
 

lib/IRGen/GenThunk.cpp

@@ -103,7 +103,7 @@ static FunctionPointer lookupMethod(IRGenFunction &IGF, SILDeclRef declRef) {
 void IRGenModule::emitDispatchThunk(SILDeclRef declRef) {
   auto *f = getAddrOfDispatchThunk(declRef, ForDefinition);
   if (!f->isDeclaration()) {
-    f->deleteBody();
+    return;
   }
 
   IRGenFunction IGF(*this, f);
@@ -167,7 +167,8 @@ IRGenModule::getAddrOfMethodLookupFunction(ClassDecl *classDecl,
 void IRGenModule::emitMethodLookupFunction(ClassDecl *classDecl) {
   auto *f = getAddrOfMethodLookupFunction(classDecl, ForDefinition);
   if (!f->isDeclaration()) {
-    f->deleteBody();
+    assert(IRGen.isLazilyReemittingNominalTypeDescriptor(classDecl));
+    return;
   }
 
   IRGenFunction IGF(*this, f);

lib/IRGen/IRGenModule.h

@@ -279,6 +279,8 @@ class IRGenerator {
   llvm::SmallVector<std::pair<CanType, TypeMetadataCanonicality>, 4>
       LazySpecializedTypeMetadataRecords;
 
+  llvm::SmallPtrSet<NominalTypeDecl *, 4> LazilyReemittedTypeContextDescriptors;
+
   /// The queue of metadata accessors to emit.
   ///
   /// The accessors must be emitted after everything else which might result in
@@ -436,6 +438,15 @@ class IRGenerator {
     return MetadataPrespecializationsForGenericTypes.lookup(type);
   }
 
+  void noteLazyReemissionOfNominalTypeDescriptor(NominalTypeDecl *decl) {
+    LazilyReemittedTypeContextDescriptors.insert(decl);
+  }
+
+  bool isLazilyReemittingNominalTypeDescriptor(NominalTypeDecl *decl) {
+    return LazilyReemittedTypeContextDescriptors.find(decl) !=
+           std::end(LazilyReemittedTypeContextDescriptors);
+  }
+
   void noteUseOfMetadataAccessor(NominalTypeDecl *decl) {
     if (LazyMetadataAccessors.count(decl) == 0) {
       LazyMetadataAccessors.insert(decl);