[PATCH v18 26/40] libstdc++: Optimize is_object trait performance

[Ken Matsui]

This patch optimizes the performance of the is_object trait by dispatching to
the new __is_function and __is_reference built-in traits.

libstdc++-v3/ChangeLog:
        * include/std/type_traits (is_object): Use __is_function and
        __is_reference built-in traits.
        (is_object_v): Likewise.

Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/libstdc++-v3/include/std/type_traits 
b/libstdc++-v3/include/std/type_traits
index bd57488824b..674d398c075 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -725,11 +725,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     { };
 
   /// is_object
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function) \
+ && _GLIBCXX_USE_BUILTIN_TRAIT(__is_reference)
+  template<typename _Tp>
+    struct is_object
+    : public __bool_constant<!(__is_function(_Tp) || __is_reference(_Tp)
+                             || is_void<_Tp>::value)>
+    { };
+#else
   template<typename _Tp>
     struct is_object
     : public __not_<__or_<is_function<_Tp>, is_reference<_Tp>,
                           is_void<_Tp>>>::type
     { };
+#endif
 
   template<typename>
     struct is_member_pointer;
@@ -3305,8 +3314,17 @@ template <typename _Tp>
   inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
 template <typename _Tp>
   inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
+
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function) \
+ && _GLIBCXX_USE_BUILTIN_TRAIT(__is_reference)
+template <typename _Tp>
+  inline constexpr bool is_object_v
+    = !(__is_function(_Tp) || __is_reference(_Tp) || is_void<_Tp>::value);
+#else
 template <typename _Tp>
   inline constexpr bool is_object_v = is_object<_Tp>::value;
+#endif
+
 template <typename _Tp>
   inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
 template <typename _Tp>
-- 
2.42.0