[libc++][libc++abi] Minor follow-up changes after ptrauth upstreaming (#87481)

This patch applies the comments provided on #84573. This is done as a
separate PR to avoid merge conflicts with downstreams that already had
ptrauth support.

(cherry picked from commit e64e745)

Author: ldionne

libcxx/include/typeinfo

@@ -275,13 +275,14 @@ struct __type_info_implementations {
           __impl;
 };
 
-#    if defined(__arm64__) && __has_cpp_attribute(clang::ptrauth_vtable_pointer)
-#      if __has_feature(ptrauth_type_info_discriminated_vtable_pointer)
+#    if __has_cpp_attribute(_Clang::__ptrauth_vtable_pointer__)
+#      if __has_feature(ptrauth_type_info_vtable_pointer_discrimination)
 #        define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH                                                                  \
-          [[clang::ptrauth_vtable_pointer(process_independent, address_discrimination, type_discrimination)]]
+          [[_Clang::__ptrauth_vtable_pointer__(process_independent, address_discrimination, type_discrimination)]]
 #      else
 #        define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH                                                                  \
-          [[clang::ptrauth_vtable_pointer(process_independent, no_address_discrimination, no_extra_discrimination)]]
+          [[_Clang::__ptrauth_vtable_pointer__(                                                                        \
+              process_independent, no_address_discrimination, no_extra_discrimination)]]
 #      endif
 #    else
 #      define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH

libcxx/src/include/overridable_function.h

@@ -13,7 +13,7 @@
 #include <__config>
 #include <cstdint>
 
-#if defined(__arm64e__) && __has_feature(ptrauth_calls)
+#if __has_feature(ptrauth_calls)
 #  include <ptrauth.h>
 #endif
 
@@ -83,13 +83,13 @@ _LIBCPP_HIDE_FROM_ABI bool __is_function_overridden(_Ret (*__fptr)(_Args...)) no
   uintptr_t __end   = reinterpret_cast<uintptr_t>(&__lcxx_override_end);
   uintptr_t __ptr   = reinterpret_cast<uintptr_t>(__fptr);
 
-#if defined(__arm64e__) && __has_feature(ptrauth_calls)
+#  if __has_feature(ptrauth_calls)
   // We must pass a void* to ptrauth_strip since it only accepts a pointer type. Also, in particular,
   // we must NOT pass a function pointer, otherwise we will strip the function pointer, and then attempt
   // to authenticate and re-sign it when casting it to a uintptr_t again, which will fail because we just
   // stripped the function pointer. See rdar://122927845.
   __ptr = reinterpret_cast<uintptr_t>(ptrauth_strip(reinterpret_cast<void*>(__ptr), ptrauth_key_function_pointer));
-#endif
+#  endif
 
   // Finally, the function was overridden if it falls outside of the section's bounds.
   return __ptr < __start || __ptr > __end;

libcxxabi/src/private_typeinfo.cpp

@@ -55,15 +55,12 @@
 #include <ptrauth.h>
 #endif
 
-
-template<typename T>
-static inline
-T *
-get_vtable(T *vtable) {
+template <typename T>
+static inline T* strip_vtable(T* vtable) {
 #if __has_feature(ptrauth_calls)
-    vtable = ptrauth_strip(vtable, ptrauth_key_cxx_vtable_pointer);
+  vtable = ptrauth_strip(vtable, ptrauth_key_cxx_vtable_pointer);
 #endif
-    return vtable;
+  return vtable;
 }
 
 static inline
@@ -117,11 +114,10 @@ void dyn_cast_get_derived_info(derived_object_info* info, const void* static_ptr
         reinterpret_cast<const uint8_t*>(vtable) + offset_to_ti_proxy;
     info->dynamic_type = *(reinterpret_cast<const __class_type_info* const*>(ptr_to_ti_proxy));
 #else
-    void **vtable = *static_cast<void ** const *>(static_ptr);
-    vtable = get_vtable(vtable);
-    info->offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
-    info->dynamic_ptr = static_cast<const char*>(static_ptr) + info->offset_to_derived;
-    info->dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);
+  void** vtable = strip_vtable(*static_cast<void** const*>(static_ptr));
+  info->offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
+  info->dynamic_ptr = static_cast<const char*>(static_ptr) + info->offset_to_derived;
+  info->dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);
 #endif
 }
 
@@ -576,8 +572,7 @@ __base_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
        find the layout.  */
     offset_to_base = __offset_flags >> __offset_shift;
     if (is_virtual) {
-      const char* vtable = *static_cast<const char* const*>(adjustedPtr);
-      vtable = get_vtable(vtable);
+      const char* vtable = strip_vtable(*static_cast<const char* const*>(adjustedPtr));
       offset_to_base = update_offset_to_base(vtable, offset_to_base);
     }
   } else if (!is_virtual) {
@@ -1517,9 +1512,8 @@ __base_class_type_info::search_above_dst(__dynamic_cast_info* info,
     ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
     if (__offset_flags & __virtual_mask)
     {
-        const char* vtable = *static_cast<const char*const*>(current_ptr);
-        vtable = get_vtable(vtable);
-        offset_to_base = update_offset_to_base(vtable, offset_to_base);
+      const char* vtable = strip_vtable(*static_cast<const char* const*>(current_ptr));
+      offset_to_base = update_offset_to_base(vtable, offset_to_base);
     }
     __base_type->search_above_dst(info, dst_ptr,
                                   static_cast<const char*>(current_ptr) + offset_to_base,
@@ -1538,9 +1532,8 @@ __base_class_type_info::search_below_dst(__dynamic_cast_info* info,
     ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
     if (__offset_flags & __virtual_mask)
     {
-        const char* vtable = *static_cast<const char*const*>(current_ptr);
-        vtable = get_vtable(vtable);
-        offset_to_base = update_offset_to_base(vtable, offset_to_base);
+      const char* vtable = strip_vtable(*static_cast<const char* const*>(current_ptr));
+      offset_to_base = update_offset_to_base(vtable, offset_to_base);
     }
     __base_type->search_below_dst(info,
                                   static_cast<const char*>(current_ptr) + offset_to_base,