From c9a92c2a8db0d3a23a57a264839ce883ce22602e Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Tue, 11 Mar 2014 00:25:05 +0000
Subject: [PATCH] Objective-C IRGen. Fixes several regressions caused by
 changes made to setting of ObjC linkages. //rdar://16206443

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203521 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGObjCMac.cpp                    | 36 +++++++++++++++++---
 test/CodeGenObjC/weak-metaclass-visibility.m | 33 ++++++++++++++++++
 2 files changed, 64 insertions(+), 5 deletions(-)
 create mode 100644 test/CodeGenObjC/weak-metaclass-visibility.m

diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 8bc14f6483..80a0324d0c 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -890,6 +890,9 @@ protected:
 
   /// DefinedClasses - List of defined classes.
   SmallVector<llvm::GlobalValue*, 16> DefinedClasses;
+  
+  /// ImplementedClasses - List of @implemented classes.
+  SmallVector<const ObjCInterfaceDecl*, 16> ImplementedClasses;
 
   /// DefinedNonLazyClasses - List of defined "non-lazy" classes.
   SmallVector<llvm::GlobalValue*, 16> DefinedNonLazyClasses;
@@ -1323,7 +1326,7 @@ private:
                                             llvm::Constant *SuperClassGV,
                                             llvm::Constant *ClassRoGV,
                                             bool HiddenVisibility,
-                                            bool Weak = false);
+                                            bool Weak);
 
   llvm::Constant *GetMethodConstant(const ObjCMethodDecl *MD);
 
@@ -3156,6 +3159,7 @@ void CGObjCMac::GenerateClass(const ObjCImplementationDecl *ID) {
     GV = CreateMetadataVar(Name, Init, Section, 4, true);
   assertPrivateName(GV);
   DefinedClasses.push_back(GV);
+  ImplementedClasses.push_back(Interface);
   // method definition entries must be clear for next implementation.
   MethodDefinitions.clear();
 }
@@ -4404,9 +4408,17 @@ llvm::Constant *CGObjCMac::EmitModuleSymbols() {
   // The runtime expects exactly the list of defined classes followed
   // by the list of defined categories, in a single array.
   SmallVector<llvm::Constant*, 8> Symbols(NumClasses + NumCategories);
-  for (unsigned i=0; i<NumClasses; i++)
+  for (unsigned i=0; i<NumClasses; i++) {
+    const ObjCInterfaceDecl *ID = ImplementedClasses[i];
+    assert(ID);
+    if (ObjCImplementationDecl *IMP = ID->getImplementation())
+      // We are implementing a weak imported interface. Give it external linkage
+      if (ID->isWeakImported() && !IMP->isWeakImported())
+        DefinedClasses[i]->setLinkage(llvm::GlobalVariable::ExternalLinkage);
+    
     Symbols[i] = llvm::ConstantExpr::getBitCast(DefinedClasses[i],
                                                 ObjCTypes.Int8PtrTy);
+  }
   for (unsigned i=0; i<NumCategories; i++)
     Symbols[NumClasses + i] =
       llvm::ConstantExpr::getBitCast(DefinedCategories[i],
@@ -5534,6 +5546,16 @@ void CGObjCNonFragileABIMac::FinishNonFragileABIModule() {
 
   // Build list of all implemented class addresses in array
   // L_OBJC_LABEL_CLASS_$.
+
+  for (unsigned i=0, NumClasses=ImplementedClasses.size(); i<NumClasses; i++) {
+    const ObjCInterfaceDecl *ID = ImplementedClasses[i];
+    assert(ID);
+    if (ObjCImplementationDecl *IMP = ID->getImplementation())
+      // We are implementing a weak imported interface. Give it external linkage
+      if (ID->isWeakImported() && !IMP->isWeakImported())
+        DefinedClasses[i]->setLinkage(llvm::GlobalVariable::ExternalLinkage);
+  }
+  
   AddModuleClassList(DefinedClasses,
                      "\01L_OBJC_LABEL_CLASS_$",
                      "__DATA, __objc_classlist, regular, no_dead_strip");
@@ -5833,7 +5855,8 @@ void CGObjCNonFragileABIMac::GenerateClass(const ObjCImplementationDecl *ID) {
   if (!ID->getClassInterface()->getSuperClass()) {
     // class is root
     flags |= NonFragileABI_Class_Root;
-    SuperClassGV = GetClassGlobal(ObjCClassName + ClassName);
+    SuperClassGV = GetClassGlobal(ObjCClassName + ClassName,
+                                  ID->getClassInterface()->isWeakImported());
     IsAGV = GetClassGlobal(ObjCMetaClassName + ClassName,
                            ID->getClassInterface()->isWeakImported());
 
@@ -5906,8 +5929,10 @@ void CGObjCNonFragileABIMac::GenerateClass(const ObjCImplementationDecl *ID) {
   TClassName = ObjCClassName + ClassName;
   llvm::GlobalVariable *ClassMD =
     BuildClassMetaData(TClassName, MetaTClass, SuperClassGV, CLASS_RO_GV,
-                       classIsHidden);
+                       classIsHidden,
+                       ID->getClassInterface()->isWeakImported());
   DefinedClasses.push_back(ClassMD);
+  ImplementedClasses.push_back(ID->getClassInterface());
 
   // Determine if this class is also "non-lazy".
   if (ImplementationIsNonLazy(ID))
@@ -6697,7 +6722,8 @@ CGObjCNonFragileABIMac::EmitSuperClassRef(CodeGenFunction &CGF,
 
   if (!Entry) {
     std::string ClassName(getClassSymbolPrefix() + ID->getNameAsString());
-    llvm::GlobalVariable *ClassGV = GetClassGlobal(ClassName);
+    llvm::GlobalVariable *ClassGV = GetClassGlobal(ClassName,
+                                                   ID->isWeakImported());
     Entry =
       new llvm::GlobalVariable(CGM.getModule(), ObjCTypes.ClassnfABIPtrTy,
                                false, llvm::GlobalValue::PrivateLinkage,
diff --git a/test/CodeGenObjC/weak-metaclass-visibility.m b/test/CodeGenObjC/weak-metaclass-visibility.m
new file mode 100644
index 0000000000..1f76197d84
--- /dev/null
+++ b/test/CodeGenObjC/weak-metaclass-visibility.m
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s | FileCheck %s
+// rdar://16206443
+
+@interface NSObject 
+- (void) finalize;
+@end
+
+__attribute__((availability(macosx,introduced=9876.5)))
+@interface MyClass : NSObject
++ (void)someClassMethod;
+- (void)someInstanceMethod;
+@end
+
+@implementation MyClass
++ (void)someClassMethod {
+}
+
+- (void)someInstanceMethod {
+    [MyClass someClassMethod];
+    [super finalize];
+}
+@end
+
+void kit()
+{
+    MyClass *wrapper = [MyClass alloc];
+}
+
+// CHECK: @"OBJC_CLASS_$_MyClass" = global %struct._class_t
+// CHECK: @"OBJC_METACLASS_$_NSObject" = external global %struct._class_t
+// CHECK: @"OBJC_METACLASS_$_MyClass" = global %struct._class_t
+// CHECK: @"OBJC_CLASS_$_NSObject" = external global %struct._class_t
+
-- 
2.50.1