IRGen: Clean up emitObjCClassSymbol() to improve code reuse

Author: slavapestov

lib/IRGen/GenMeta.cpp

@@ -3044,23 +3044,17 @@ namespace {
 /// references, we emit the symbol as a global asm block.
 static void emitObjCClassSymbol(IRGenModule &IGM,
                                 ClassDecl *classDecl,
-                                llvm::GlobalValue *metadata) {
-  llvm::SmallString<32> classSymbol;
-  LinkEntity::forObjCClass(classDecl).mangle(classSymbol);
-  
-  // Create the alias.
-  auto *metadataTy = cast<llvm::PointerType>(metadata->getType());
+                                llvm::Constant *metadata) {
+  auto entity = LinkEntity::forObjCClass(classDecl);
+  LinkInfo link = LinkInfo::get(IGM, entity, ForDefinition);
 
   // Create the alias.
-  auto *alias = llvm::GlobalAlias::create(metadataTy->getElementType(),
-                                          metadataTy->getAddressSpace(),
-                                          metadata->getLinkage(),
-                                          classSymbol.str(), metadata,
-                                          IGM.getModule());
-  alias->setVisibility(metadata->getVisibility());
-
-  if (IGM.useDllStorage())
-    alias->setDLLStorageClass(metadata->getDLLStorageClass());
+  auto *ptrTy = cast<llvm::PointerType>(metadata->getType());
+  auto *alias = llvm::GlobalAlias::create(
+      ptrTy->getElementType(), ptrTy->getAddressSpace(), link.getLinkage(),
+      link.getName(), metadata, &IGM.Module);
+  ApplyIRLinkage({link.getLinkage(), link.getVisibility(), link.getDLLStorage()})
+      .to(alias);
 }
 
 /// Emit the type metadata or metadata template for a class.