Prepare libcxx and libcxxabi for pointer field protection.

libcxx/CMakeLists.txt

@@ -201,7 +201,11 @@ set(LIBCXX_LIBRARY_VERSION "${LIBCXX_ABI_VERSION}.0" CACHE STRING
    For example, -DLIBCXX_LIBRARY_VERSION=x.y will result in the library being named
    libc++.x.y.dylib, along with the usual symlinks pointing to that. On Apple platforms,
    this also controls the linker's 'current_version' property.")
-set(LIBCXX_ABI_NAMESPACE "__${LIBCXX_ABI_VERSION}" CACHE STRING "The inline ABI namespace used by libc++. It defaults to __n where `n` is the current ABI version.")
+set(default_abi_namespace "__${LIBCXX_ABI_VERSION}")
+if(NOT LIBCXX_PFP STREQUAL "none")
+  set(default_abi_namespace "${default_abi_namespace}_pfp_${LIBCXX_PFP}")
+endif()
+set(LIBCXX_ABI_NAMESPACE "${default_abi_namespace}" CACHE STRING "The inline ABI namespace used by libc++. It defaults to __n where `n` is the current ABI version.")
 if (NOT LIBCXX_ABI_NAMESPACE MATCHES "__.*")
   message(FATAL_ERROR "LIBCXX_ABI_NAMESPACE must be a reserved identifier, got '${LIBCXX_ABI_NAMESPACE}'.")
 endif()

libcxx/include/__config

@@ -1263,6 +1263,12 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 0
 #  endif
 
+#  if __has_cpp_attribute(_Clang::__no_field_protection__)
+#    define _LIBCPP_NO_PFP [[_Clang::__no_field_protection__]]
+#  else
+#    define _LIBCPP_NO_PFP
+#  endif
+
 #endif // __cplusplus
 
 #endif // _LIBCPP___CONFIG

libcxx/include/__type_traits/is_trivially_relocatable.h

@@ -34,10 +34,13 @@ template <class _Tp, class = void>
 struct __libcpp_is_trivially_relocatable : is_trivially_copyable<_Tp> {};
 #endif
 
+// __trivially_relocatable on libc++'s builtin types does not currently return the right answer with PFP.
+#if !defined(__POINTER_FIELD_PROTECTION__)
 template <class _Tp>
 struct __libcpp_is_trivially_relocatable<_Tp,
                                          __enable_if_t<is_same<_Tp, typename _Tp::__trivially_relocatable>::value> >
     : true_type {};
+#endif
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/typeinfo

@@ -300,7 +300,7 @@ class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH type_info
 protected:
   typedef __type_info_implementations::__impl __impl;
 
-  __impl::__type_name_t __type_name;
+  _LIBCPP_NO_PFP __impl::__type_name_t __type_name;
 
   _LIBCPP_HIDE_FROM_ABI explicit type_info(const char* __n) : __type_name(__impl::__string_to_type_name(__n)) {}
 

libcxxabi/include/__cxxabi_config.h

@@ -109,4 +109,10 @@
 #  define _LIBCXXABI_NOEXCEPT noexcept
 #endif
 
+#if defined(__POINTER_FIELD_PROTECTION__)
+#  define _LIBCXXABI_NO_PFP [[_Clang::__no_field_protection__]]
+#else
+#  define _LIBCXXABI_NO_PFP
+#endif
+
 #endif // ____CXXABI_CONFIG_H

libcxxabi/src/private_typeinfo.h

@@ -145,7 +145,7 @@ class _LIBCXXABI_TYPE_VIS __class_type_info : public __shim_type_info {
 // Has one non-virtual public base class at offset zero
 class _LIBCXXABI_TYPE_VIS __si_class_type_info : public __class_type_info {
 public:
-  const __class_type_info *__base_type;
+  _LIBCXXABI_NO_PFP const __class_type_info *__base_type;
 
   _LIBCXXABI_HIDDEN virtual ~__si_class_type_info();
 
@@ -204,7 +204,7 @@ class _LIBCXXABI_TYPE_VIS __vmi_class_type_info : public __class_type_info {
 class _LIBCXXABI_TYPE_VIS __pbase_type_info : public __shim_type_info {
 public:
   unsigned int __flags;
-  const __shim_type_info *__pointee;
+  _LIBCXXABI_NO_PFP const __shim_type_info *__pointee;
 
   enum __masks {
     __const_mask = 0x1,
@@ -245,7 +245,7 @@ class _LIBCXXABI_TYPE_VIS __pointer_type_info : public __pbase_type_info {
 class _LIBCXXABI_TYPE_VIS __pointer_to_member_type_info
     : public __pbase_type_info {
 public:
-  const __class_type_info *__context;
+  _LIBCXXABI_NO_PFP const __class_type_info *__context;
 
   _LIBCXXABI_HIDDEN virtual ~__pointer_to_member_type_info();
   _LIBCXXABI_HIDDEN virtual bool can_catch(const __shim_type_info *,