[PATCH v18 32/40] libstdc++: Optimize is_arithmetic trait performance

[Ken Matsui]

This patch optimizes the performance of the is_arithmetic trait by dispatching
to the new __is_arithmetic built-in trait.

libstdc++-v3/ChangeLog:

        * include/std/type_traits (is_arithmetic): Use __is_arithmetic
        built-in trait.
        (is_arithmetic_v): Likewise.

Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/libstdc++-v3/include/std/type_traits 
b/libstdc++-v3/include/std/type_traits
index 3acd843f2f2..cc466e0f606 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -726,10 +726,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #endif
 
   /// is_arithmetic
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_arithmetic)
+  template<typename _Tp>
+    struct is_arithmetic
+    : public __bool_constant<__is_arithmetic(_Tp)>
+    { };
+#else
   template<typename _Tp>
     struct is_arithmetic
     : public __or_<is_integral<_Tp>, is_floating_point<_Tp>>::type
     { };
+#endif
 
   /// is_fundamental
   template<typename _Tp>
@@ -3344,8 +3351,14 @@ template <typename _Tp>
   inline constexpr bool is_reference_v<_Tp&&> = true;
 #endif
 
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_arithmetic)
+template <typename _Tp>
+  inline constexpr bool is_arithmetic_v = __is_arithmetic(_Tp);
+#else
 template <typename _Tp>
   inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
+#endif
+
 template <typename _Tp>
   inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
 
-- 
2.42.0