[clang][CGObjC] Sign the v-table pointer in ObjC exception RTTI.

clang/docs/ReleaseNotes.rst

@@ -317,6 +317,7 @@ Non-comprehensive list of changes in this release
   ``sizeof`` or ``typeof`` expression. (#GH138444)
 - Deprecation warning is emitted for the deprecated ``__reference_binds_to_temporary`` intrinsic.
   ``__reference_constructs_from_temporary`` should be used instead. (#GH44056)
+- Support pointer authentication for Objective-C exception `type_info` objects
 
 New Compiler Flags
 ------------------

clang/lib/CodeGen/CGObjCMac.cpp

@@ -7676,10 +7676,21 @@ CGObjCNonFragileABIMac::GetInterfaceEHType(const ObjCInterfaceDecl *ID,
   }
 
   llvm::Value *VTableIdx = llvm::ConstantInt::get(CGM.Int32Ty, 2);
+  llvm::Constant *VTablePtr = llvm::ConstantExpr::getInBoundsGetElementPtr(
+      VTableGV->getValueType(), VTableGV, VTableIdx);
+
   ConstantInitBuilder builder(CGM);
   auto values = builder.beginStruct(ObjCTypes.EHTypeTy);
-  values.add(llvm::ConstantExpr::getInBoundsGetElementPtr(
-      VTableGV->getValueType(), VTableGV, VTableIdx));
+
+  if (auto &Schema =
+          CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer) {
+    assert(!Schema.hasOtherDiscrimination() ||
+           Schema.getOtherDiscrimination() ==
+               PointerAuthSchema::Discrimination::Constant);
+    values.addSignedPointer(VTablePtr, Schema, GlobalDecl(), QualType());
+  } else {
+    values.add(VTablePtr);
+  }
   values.add(GetClassName(ClassName));
   values.add(GetClassGlobal(ID, /*metaclass*/ false, NotForDefinition));
 

clang/test/CodeGenObjC/ptrauth-attr-exception.m

@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple arm64-apple-ios                                                   -fptrauth-calls -emit-llvm -fexceptions -fobjc-exceptions -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-type-info-vtable-pointer-discrimination -fptrauth-calls -emit-llvm -fexceptions -fobjc-exceptions -o - %s | FileCheck --check-prefix=TYPEDISC_TYPEINFO %s
+
+__attribute__((objc_root_class))
+@interface Root {
+  Class isa;
+}
+@end
+
+__attribute__((objc_exception))
+@interface A : Root
+@end
+
+@implementation A
+@end
+
+            // CHECK: @"OBJC_EHTYPE_$_A" = global {{%.*}} { ptr ptrauth (ptr getelementptr inbounds (ptr, ptr @objc_ehtype_vtable, i32 2), i32 2),
+// TYPEDISC_TYPEINFO: @"OBJC_EHTYPE_$_A" = global {{%.*}} { ptr ptrauth (ptr getelementptr inbounds (ptr, ptr @objc_ehtype_vtable, i32 2), i32 2, i64 45546, ptr @"OBJC_EHTYPE_$_A"),