libstdc++: Optimize std::is_member_pointer compilation performance

This patch optimizes the compilation performance of std::is_member_pointer
by dispatching to the new __is_member_pointer built-in trait.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_member_pointer): Use
	__is_member_pointer built-in trait.
	(is_member_pointer_v): Likewise.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 4a5068791af7bce5487e7c19e9d2f7f7579382a4..4ab1d29ff51ae5a04814ae1029338ae5220a268d 100644 (file)
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -716,6 +716,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     struct is_compound
     : public __not_<is_fundamental<_Tp>>::type { };
 
+  /// is_member_pointer
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_pointer)
+  template<typename _Tp>
+    struct is_member_pointer
+    : public __bool_constant<__is_member_pointer(_Tp)>
+    { };
+#else
   /// @cond undocumented
   template<typename _Tp>
     struct __is_member_pointer_helper
@@ -726,11 +733,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public true_type { };
   /// @endcond
 
-  /// is_member_pointer
   template<typename _Tp>
     struct is_member_pointer
     : public __is_member_pointer_helper<__remove_cv_t<_Tp>>::type
     { };
+#endif
 
   template<typename, typename>
     struct is_same;
@@ -3228,8 +3235,15 @@ template <typename _Tp>
   inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
 template <typename _Tp>
   inline constexpr bool is_compound_v = is_compound<_Tp>::value;
+
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_pointer)
+template <typename _Tp>
+  inline constexpr bool is_member_pointer_v = __is_member_pointer(_Tp);
+#else
 template <typename _Tp>
   inline constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
+#endif
+
 template <typename _Tp>
   inline constexpr bool is_const_v = false;
 template <typename _Tp>