| Message ID | 20240511090130.248174-8-kmatsui@gcc.gnu.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v26,01/13] libstdc++: Optimize std::is_const compilation performance | expand |
On 11/05/24 02:01 -0700, Ken Matsui wrote: >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(+) > >diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits >index 5b74e44d0a6..effa3fbcb75 100644 >--- a/libstdc++-v3/include/std/type_traits >+++ b/libstdc++-v3/include/std/type_traits >@@ -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; This still requires instantiating a class template, which means that all uses of __add_lval_ref_t (e.g. in is_copy_constructible) still instantiate __add_lvalue_reference_helper. Could we do this instead, and then no change to std::add_lvalue_reference is needed? /// @cond undocumented #if _GLIBCXX_USE_BUILTIN_TRAIT(__add_lvalue_reference) template<typename _Tp> using __add_lval_ref_t = __add_lvalue_reference(_Tp); #else template<typename _Tp, typename = void> struct __add_lvalue_reference_helper { using type = _Tp; }; template<typename _Tp> struct __add_lvalue_reference_helper<_Tp, __void_t<_Tp&>> { using type = _Tp&; }; template<typename _Tp> using __add_lval_ref_t = typename __add_lvalue_reference_helper<_Tp>::type; #endif /// @endcond We never use __add_lval_ref_t in a context that requires it to be mangled, so I think this is OK. >@@ -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> >-- >2.44.0 >
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index 5b74e44d0a6..effa3fbcb75 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -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>
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(+)