IRGen: Remove usages of ArchetypeType::getParent()

Author: slavapestov

lib/IRGen/GenArchetype.cpp

@@ -79,7 +79,7 @@ irgen::emitArchetypeTypeMetadataRef(IRGenFunction &IGF,
   }
 
 #ifndef NDEBUG
-  if (!archetype->getParent()) {
+  if (archetype->isRoot()) {
     llvm::errs() << "Metadata for archetype not bound in function.\n"
                  << "  The metadata could be missing entirely because it needs "
                     "to be passed to the function.\n"
@@ -98,12 +98,12 @@ irgen::emitArchetypeTypeMetadataRef(IRGenFunction &IGF,
   }
 #endif
   // If there's no local or opaque metadata, it must be a nested type.
-  assert(archetype->getParent() && "Not a nested archetype");
+  auto *member = archetype->getInterfaceType()->castTo<DependentMemberType>();
 
-  CanArchetypeType parent(archetype->getParent());
-  AssociatedType association(
-      archetype->getInterfaceType()->castTo<DependentMemberType>()
-        ->getAssocType());
+  auto parent = cast<ArchetypeType>(
+    archetype->getGenericEnvironment()->mapTypeIntoContext(
+      member->getBase())->getCanonicalType());
+  AssociatedType association(member->getAssocType());
 
   MetadataResponse response =
     emitAssociatedTypeMetadataRef(IGF, parent, association, request);