[ObjC] Use the name specified by objc_runtime_name instead of the class identifier

[ahatanak]

Summary

This patch fixes a few places in CGObjCMac.cpp where the class identifier was used instead of the name specified by objc_runtime_name.

rdar://problem/37910822

[ahatanak]

Note that CGObjCNonFragileABIMac::EmitClassRef also passes the class identifier to CGObjCNonFragileABIMac::EmitClassRefFromId, but it doesn't cause a problem. CGObjCNonFragileABIMac::EmitClassRefFromId uses the identifier only when the ObjCInterfaceDecl passed to it is null and that happens only when it is called from CGObjCNonFragileABIMac::EmitNSAutoreleasePoolClassRef.

[rjmccall]

In D45101#1053246, @ahatanak wrote:

Note that CGObjCNonFragileABIMac::EmitClassRef also passes the class identifier to CGObjCNonFragileABIMac::EmitClassRefFromId, but it doesn't cause a problem. CGObjCNonFragileABIMac::EmitClassRefFromId uses the identifier only when the ObjCInterfaceDecl passed to it is null and that happens only when it is called from CGObjCNonFragileABIMac::EmitNSAutoreleasePoolClassRef.

Hmm. Alright.

LGTM.

cfe/trunk/lib/CodeGen/CGObjCMac.cpp

/*
   // Objective-C 1.0 extensions (<rdr://4585769>)
   const char *ivar_layout;
   struct _objc_class_ext *ext;
   };
 
   See EmitClassExtension();
 */
 void CGObjCMac::GenerateClass(const ObjCImplementationDecl *ID) {
-  DefinedSymbols.insert(ID->getIdentifier());
+  IdentifierInfo *RuntimeName =
+      &CGM.getContext().Idents.get(ID->getObjCRuntimeNameAsString());
+  DefinedSymbols.insert(RuntimeName);
 
   std::string ClassName = ID->getNameAsString();
   // FIXME: Gross
   ObjCInterfaceDecl *Interface =
     const_cast<ObjCInterfaceDecl*>(ID->getClassInterface());
   llvm::Constant *Protocols =
       EmitProtocolList("OBJC_CLASS_PROTOCOLS_" + ID->getName(),
                        Interface->all_referenced_protocol_begin(),

 
 llvm::Value *CGObjCMac::EmitClassRef(CodeGenFunction &CGF,
                                      const ObjCInterfaceDecl *ID) {
   // If the class has the objc_runtime_visible attribute, we need to
   // use the Objective-C runtime to get the class.
   if (ID->hasAttr<ObjCRuntimeVisibleAttr>())
     return EmitClassRefViaRuntime(CGF, ID, ObjCTypes);
 
-  return EmitClassRefFromId(CGF, ID->getIdentifier());
+  IdentifierInfo *RuntimeName =
+      &CGM.getContext().Idents.get(ID->getObjCRuntimeNameAsString());
+  return EmitClassRefFromId(CGF, RuntimeName);
 }
 
 llvm::Value *CGObjCMac::EmitNSAutoreleasePoolClassRef(CodeGenFunction &CGF) {
   IdentifierInfo *II = &CGM.getContext().Idents.get("NSAutoreleasePool");
   return EmitClassRefFromId(CGF, II);
 }
 
 llvm::Value *CGObjCMac::EmitSelector(CodeGenFunction &CGF, Selector Sel) {

cfe/trunk/test/CodeGenObjC/objc-runtime-name.m

+// RUN: %clang_cc1 -triple i386-apple-macosx10.13.0 -fobjc-runtime=macosx-fragile-10.13.0 -fobjc-subscripting-legacy-runtime -emit-llvm -o - %s | FileCheck %s
+
+// Check that the runtime name is emitted and used instead of the class
+// identifier.
+
+// CHECK: module asm {{.*}}objc_class_name_XYZ=0
+// CHECK: module asm {{.*}}globl .objc_class_name_XYZ
+// CHECK: module asm {{.*}}lazy_reference .objc_class_name_XYZ
+
+// CHECK: @[[OBJC_CLASS_NAME:.*]] = private unnamed_addr constant [4 x i8] c"XYZ{{.*}}, section "__TEXT,__cstring,cstring_literals",
+// CHECK: = private global {{.*}} bitcast ([4 x i8]* @[[OBJC_CLASS_NAME]] to {{.*}}), section "__OBJC,__cls_refs,literal_pointers,no_dead_strip"
+
+__attribute__((objc_root_class,objc_runtime_name("XYZ")))
+@interface A
++(void)m1;
+@end
+
+@implementation A
++(void)m1 {}
+@end
+
+void test(void) {
+  [A m1];
+}