[v13,16/26] libstdc++: Optimize std::add_lvalue_reference compilation performance
Commit Message
This patch optimizes the compilation performance of
std::add_lvalue_reference by dispatching to the new
__add_lvalue_reference built-in trait.
libstdc++-v3/ChangeLog:
* include/std/type_traits (add_lvalue_reference): Use
__add_lvalue_reference built-in trait.
(__add_lvalue_reference_helper): Likewise.
Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
libstdc++-v3/include/std/type_traits | 12 ++++++++++++
1 file changed, 12 insertions(+)
@@ -1157,6 +1157,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
};
/// @cond undocumented
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__add_lvalue_reference)
+ template<typename _Tp>
+ struct __add_lvalue_reference_helper
+ { using type = __add_lvalue_reference(_Tp); };
+#else
template<typename _Tp, typename = void>
struct __add_lvalue_reference_helper
{ using type = _Tp; };
@@ -1164,6 +1169,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
struct __add_lvalue_reference_helper<_Tp, __void_t<_Tp&>>
{ using type = _Tp&; };
+#endif
template<typename _Tp>
using __add_lval_ref_t = typename __add_lvalue_reference_helper<_Tp>::type;
@@ -1731,9 +1737,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
/// add_lvalue_reference
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__add_lvalue_reference)
+ template<typename _Tp>
+ struct add_lvalue_reference
+ { using type = __add_lvalue_reference(_Tp); };
+#else
template<typename _Tp>
struct add_lvalue_reference
{ using type = __add_lval_ref_t<_Tp>; };
+#endif
/// add_rvalue_reference
template<typename _Tp>