libstdc++: Optimize std::remove_pointer compilation performance

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

libstdc++-v3/ChangeLog:

	* include/std/type_traits (remove_pointer): Use __remove_pointer
	built-in trait.

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 2979d79a80142737c908b8fabe45bb3cec56ce1d..f00c07f94f9c248ce9317099cc7b25699311a414 100644 (file)
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2089,6 +2089,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // Pointer modifications.
 
+  /// remove_pointer
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_pointer)
+  template<typename _Tp>
+    struct remove_pointer
+    { using type = __remove_pointer(_Tp); };
+#else
   template<typename _Tp, typename>
     struct __remove_pointer_helper
     { using type = _Tp; };
@@ -2097,11 +2103,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     struct __remove_pointer_helper<_Tp, _Up*>
     { using type = _Up; };
 
-  /// remove_pointer
   template<typename _Tp>
     struct remove_pointer
     : public __remove_pointer_helper<_Tp, __remove_cv_t<_Tp>>
     { };
+#endif
 
   template<typename _Tp, typename = void>
     struct __add_pointer_helper