[IRGen] Accommodate ObjC generic classes better

Classes using the type-erased Objective-C generics model are represented in parts of IRGen as UnboundGenericTypes, which is a problem because a number of code paths expect all generic types to be bound. Update some of these that are involved in extensions on ObjC generic types.

Author: beccadax

lib/IRGen/GenDecl.cpp

@@ -85,7 +85,7 @@ llvm::cl::opt<bool> UseBasicDynamicReplacement(
     llvm::cl::desc("Basic implementation of dynamic replacement"));
 
 namespace {
-  
+
 /// Add methods, properties, and protocol conformances from a JITed extension
 /// to an ObjC class using the ObjC runtime.
 ///
@@ -119,8 +119,8 @@ class CategoryInitializerVisitor
                                              /*allow uninitialized*/ false);
     classMetadata = Builder.CreateBitCast(classMetadata, IGM.ObjCClassPtrTy);
     metaclassMetadata = IGM.getAddrOfMetaclassObject(
-                                       origTy.getClassOrBoundGenericClass(),
-                                                         NotForDefinition);
+                          dyn_cast_or_null<ClassDecl>(origTy->getAnyNominal()),
+                          NotForDefinition);
     metaclassMetadata = llvm::ConstantExpr::getBitCast(metaclassMetadata,
                                                    IGM.ObjCClassPtrTy);
 

lib/IRGen/MetadataRequest.cpp

@@ -3411,7 +3411,7 @@ llvm::Value *irgen::emitClassHeapMetadataRef(IRGenFunction &IGF, CanType type,
                                              bool allowUninitialized) {
   assert(request.canResponseStatusBeIgnored() &&
          "emitClassHeapMetadataRef only supports satisfied requests");
-  assert(type->mayHaveSuperclass());
+  assert(type->mayHaveSuperclass() || type->isTypeErasedGenericClassType());
 
   // Archetypes may or may not be ObjC classes and need unwrapping to get at
   // the class object.
@@ -3426,7 +3426,7 @@ llvm::Value *irgen::emitClassHeapMetadataRef(IRGenFunction &IGF, CanType type,
     return classPtr;
   }
 
-  if (ClassDecl *theClass = type->getClassOrBoundGenericClass()) {
+  if (ClassDecl *theClass = dyn_cast_or_null<ClassDecl>(type->getAnyNominal())) {
     if (!hasKnownSwiftMetadata(IGF.IGM, theClass)) {
       llvm::Value *result =
         emitObjCHeapMetadataRef(IGF, theClass, allowUninitialized);

test/IRGen/objc_extensions_jit.swift

@@ -0,0 +1,16 @@
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop %s -emit-ir -disable-objc-attr-requires-foundation-module -use-jit | %FileCheck %s
+
+import Foundation
+import objc_generics
+
+extension NSString {
+  func fn() {}
+}
+
+extension GenericClass {
+  @objc func fn() {}
+}
+
+// CHECK-LABEL: define{{( dllexport)?}}{{( protected)?}} private void @runtime_registration
+// CHECK-NOT: @__swift_instantiateConcreteTypeFromMangledName
+// CHECK: ret void

test/Interpreter/objc_extensions.swift

@@ -62,3 +62,27 @@ let z: AnyObject = NSObject()
 
 // CHECK: 123
 print(z.sillyMethod())
+
+// Category on an ObjC generic class using a type-pinning parameter, including
+// a cast to an existential metatype
+@objc protocol CacheNameDefaulting {
+  static var defaultCacheName: String { get }
+}
+extension OuterClass.InnerClass: CacheNameDefaulting {
+  static var defaultCacheName: String { "InnerClasses" }
+}
+
+extension NSCache {
+  @objc convenience init(ofObjects objectTy: ObjectType.Type, forKeys keyTy: KeyType.Type) {
+    self.init()
+
+    if let defaultNameTy = objectTy as? CacheNameDefaulting.Type {
+      self.name = defaultNameTy.defaultCacheName
+    }
+  }
+}
+
+let cache = NSCache(ofObjects: OuterClass.InnerClass.self, forKeys: NSString.self)
+
+// CHECK: InnerClasses
+print(cache.name)