[PATCH v5 14/14] libstdc++: Optimize std::rank compilation performance

[Ken Matsui]

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

libstdc++-v3/ChangeLog:

        * include/std/type_traits (rank): Use __rank built-in trait.

Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libstdc++-v3/include/std/type_traits 
b/libstdc++-v3/include/std/type_traits
index 90718d772dd..5d2e6eaa2a2 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -1445,6 +1445,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     };
 
   /// rank
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__rank)
+  template<typename _Tp>
+    struct rank
+    : public integral_constant<std::size_t, __rank(_Tp)> { };
+#else
   template<typename>
     struct rank
     : public integral_constant<std::size_t, 0> { };
@@ -1456,6 +1461,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp>
     struct rank<_Tp[]>
     : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
+#endif
 
   /// extent
   template<typename, unsigned _Uint = 0>
-- 
2.43.0