[PATCH v18 33/40] libstdc++: Optimize is_fundamental trait performance

[Ken Matsui]

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

libstdc++-v3/ChangeLog:

        * include/std/type_traits (is_fundamental_v): Use __is_arithmetic
        built-in trait.
        (is_fundamental): Likewise. Optimize the original implementation.

Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/std/type_traits 
b/libstdc++-v3/include/std/type_traits
index cc466e0f606..88171e1a672 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -739,11 +739,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #endif
 
   /// is_fundamental
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_arithmetic)
+  template<typename _Tp>
+    struct is_fundamental
+    : public __bool_constant<__is_arithmetic(_Tp)
+                             || is_void<_Tp>::value
+                             || is_null_pointer<_Tp>::value>
+    { };
+#else
   template<typename _Tp>
     struct is_fundamental
-    : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
-                  is_null_pointer<_Tp>>::type
+    : public __bool_constant<is_arithmetic<_Tp>::value
+                             || is_void<_Tp>::value
+                             || is_null_pointer<_Tp>::value>
     { };
+#endif
 
   /// is_object
 #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function) \
@@ -3354,13 +3364,15 @@ template <typename _Tp>
 #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_arithmetic)
 template <typename _Tp>
   inline constexpr bool is_arithmetic_v = __is_arithmetic(_Tp);
+template <typename _Tp>
+  inline constexpr bool is_fundamental_v
+    = __is_arithmetic(_Tp) || is_void_v<_Tp> || is_null_pointer_v<_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;
+#endif
 
 #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function) \
  && _GLIBCXX_USE_BUILTIN_TRAIT(__is_reference)
-- 
2.42.0