Merge pull request #60262 from apple/egorzhdan/cxx-namespace-perf

[cxx-interop] Improve performance of importing C++ namespaces

Author: egorzhdan

lib/ClangImporter/ImportDecl.cpp

@@ -1129,11 +1129,13 @@ namespace {
       for (auto redecl : decl->redecls())
         Impl.ImportedDecls[{redecl, getVersion()}] = enumDecl;
 
-      // Because a namespaces's decl context is the bridging header, make sure
-      // we add them to the bridging header lookup table.
-      addEntryToLookupTable(*Impl.BridgingHeaderLookupTable,
-                            const_cast<clang::NamespaceDecl *>(decl),
-                            Impl.getNameImporter());
+      for (auto redecl : decl->redecls()) {
+        // Because a namespaces's decl context is the bridging header, make sure
+        // we add them to the bridging header lookup table.
+        addEntryToLookupTable(*Impl.BridgingHeaderLookupTable,
+                              const_cast<clang::NamespaceDecl *>(redecl),
+                              Impl.getNameImporter());
+      }
 
       return enumDecl;
     }

lib/ClangImporter/SwiftLookupTable.cpp

@@ -1973,21 +1973,21 @@ void importer::addEntryToLookupTable(SwiftLookupTable &table,
     llvm::SmallPtrSet<clang::Decl *, 8> alreadyAdded;
     alreadyAdded.insert(named->getCanonicalDecl());
 
-    for (auto redecl : named->redecls()) {
-      auto dc = cast<clang::DeclContext>(redecl);
-      for (auto member : dc->decls()) {
-        auto canonicalMember = member->getCanonicalDecl();
-        if (!alreadyAdded.insert(canonicalMember).second)
-          continue;
-
-        if (auto namedMember = dyn_cast<clang::NamedDecl>(canonicalMember)) {
-          // Make sure we're looking at the definition, otherwise, there won't
-          // be any members to add.
-          if (auto recordDecl = dyn_cast<clang::RecordDecl>(namedMember))
-            if (auto def = recordDecl->getDefinition())
-              namedMember = def;
-          addEntryToLookupTable(table, namedMember, nameImporter);
-        }
+    auto dc = cast<clang::DeclContext>(named);
+    for (auto member : dc->decls()) {
+      auto canonicalMember = isa<clang::NamespaceDecl>(member)
+                                 ? member
+                                 : member->getCanonicalDecl();
+      if (!alreadyAdded.insert(canonicalMember).second)
+        continue;
+
+      if (auto namedMember = dyn_cast<clang::NamedDecl>(canonicalMember)) {
+        // Make sure we're looking at the definition, otherwise, there won't
+        // be any members to add.
+        if (auto recordDecl = dyn_cast<clang::RecordDecl>(namedMember))
+          if (auto def = recordDecl->getDefinition())
+            namedMember = def;
+        addEntryToLookupTable(table, namedMember, nameImporter);
       }
     }
   }