https://gcc.gnu.org/g:9d0dba02c5452d5906f87e59455a4c38944eb217
commit r15-1251-g9d0dba02c5452d5906f87e59455a4c38944eb217
Author: Ken Matsui <kmat...@gcc.gnu.org>
Date: Thu Feb 15 04:44:54 2024 -0800
libstdc++: Optimize std::decay compilation performance
This patch optimizes the compilation performance of std::decay
by dispatching to the new __decay built-in trait.
libstdc++-v3/ChangeLog:
* include/std/type_traits (decay): Use __decay built-in trait.
Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
Reviewed-by: Patrick Palka <ppa...@redhat.com>
Reviewed-by: Jonathan Wakely <jwak...@redhat.com>
Diff:
---
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 23432ac43ac6..3d158f993a8b 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2278,6 +2278,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// @cond undocumented
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__decay)
+ template<typename _Tp>
+ struct decay
+ { using type = __decay(_Tp); };
+#else
// Decay trait for arrays and functions, used for perfect forwarding
// in make_pair, make_tuple, etc.
template<typename _Up>
@@ -2309,6 +2314,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
struct decay<_Tp&&>
{ using type = typename __decay_selector<_Tp>::type; };
+#endif
/// @cond undocumented
