On Fri, May 23, 2025 at 7:00 PM Jonathan Wakely <jwak...@redhat.com> wrote:
> Since r16-154-gc91eb5a5c13f14 std::addressof is no less efficient than
> std::__addressof, so change some uses of the latter to the former.
>
> We can't change them all, because some uses need to compile as C++98
> which only has std::__addressof.
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/stl_construct.h: Replace std::__addressof with
> std::addressof.
> * include/bits/stl_uninitialized.h: Likewise.
> ---
>
> I'm undecided whether it's better to use the standard std::addressof for
> simplicity, or to stick with std::__addressof in files where there's a
> mix of C++98 code and >= C++11 code.
>
After giving this a bit of thought. If I touch this files, then most likely
we
are implementing the new standard features, and in the patch I will just
default to std::addressof, as in any other case. So preferring to use
std::addressof when available seems like easier to maintain policy.
>
> Obviously in files that don't need to compile as C++98 (such as
> <optional>) we could just use std::addressof.
>
> Tested x86_64-linux.
>
> libstdc++-v3/include/bits/stl_construct.h | 2 +-
> libstdc++-v3/include/bits/stl_uninitialized.h | 28 +++++++++----------
> 2 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/libstdc++-v3/include/bits/stl_construct.h
> b/libstdc++-v3/include/bits/stl_construct.h
> index 23b8fb754710..a53274e33c0c 100644
> --- a/libstdc++-v3/include/bits/stl_construct.h
> +++ b/libstdc++-v3/include/bits/stl_construct.h
> @@ -82,7 +82,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> if constexpr (__cplusplus > 201703L && is_array_v<_Tp>)
> {
> for (auto& __x : *__location)
> - std::destroy_at(std::__addressof(__x));
> + std::destroy_at(std::addressof(__x));
> }
> else
> __location->~_Tp();
>
There are calls to __addressof in _Destroy at lines 212, 216, 268, 272 in
calls that are >= C++11.
If we update them, we should also change all of them in file.
> diff --git a/libstdc++-v3/include/bits/stl_uninitialized.h
> b/libstdc++-v3/include/bits/stl_uninitialized.h
> index b1428db48b00..bde787c2beaa 100644
> --- a/libstdc++-v3/include/bits/stl_uninitialized.h
> +++ b/libstdc++-v3/include/bits/stl_uninitialized.h
>
Looks like all of ones that could be updated in this file, are already.
> @@ -839,7 +839,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _UninitDestroyGuard<_ForwardIterator> __guard(__first);
> for (; __first != __last; ++__first)
> - std::_Construct(std::__addressof(*__first));
> + std::_Construct(std::addressof(*__first));
> __guard.release();
> }
> };
> @@ -856,7 +856,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> return;
>
> typename iterator_traits<_ForwardIterator>::value_type* __val
> - = std::__addressof(*__first);
> + = std::addressof(*__first);
> std::_Construct(__val);
> if (++__first != __last)
> std::fill(__first, __last, *__val);
> @@ -873,7 +873,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _UninitDestroyGuard<_ForwardIterator> __guard(__first);
> for (; __n > 0; --__n, (void) ++__first)
> - std::_Construct(std::__addressof(*__first));
> + std::_Construct(std::addressof(*__first));
> __guard.release();
> return __first;
> }
> @@ -890,7 +890,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> if (__n > 0)
> {
> typename iterator_traits<_ForwardIterator>::value_type* __val
> - = std::__addressof(*__first);
> + = std::addressof(*__first);
> std::_Construct(__val);
> ++__first;
> __first = std::fill_n(__first, __n - 1, *__val);
> @@ -955,7 +955,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> __alloc);
> typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
> for (; __first != __last; ++__first)
> - __traits::construct(__alloc, std::__addressof(*__first));
> + __traits::construct(__alloc, std::addressof(*__first));
> __guard.release();
> }
>
> @@ -980,7 +980,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> __alloc);
> typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
> for (; __n > 0; --__n, (void) ++__first)
> - __traits::construct(__alloc, std::__addressof(*__first));
> + __traits::construct(__alloc, std::addressof(*__first));
> __guard.release();
> return __first;
> }
> @@ -1007,7 +1007,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _UninitDestroyGuard<_ForwardIterator> __guard(__first);
> for (; __first != __last; ++__first)
> - std::_Construct_novalue(std::__addressof(*__first));
> + std::_Construct_novalue(std::addressof(*__first));
> __guard.release();
> }
> };
> @@ -1033,7 +1033,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _UninitDestroyGuard<_ForwardIterator> __guard(__first);
> for (; __n > 0; --__n, (void) ++__first)
> - std::_Construct_novalue(std::__addressof(*__first));
> + std::_Construct_novalue(std::addressof(*__first));
> __guard.release();
> return __first;
> }
> @@ -1089,7 +1089,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _UninitDestroyGuard<_ForwardIterator> __guard(__result);
> for (; __n > 0; --__n, (void) ++__first, ++__result)
> - std::_Construct(std::__addressof(*__result), *__first);
> + std::_Construct(std::addressof(*__result), *__first);
> __guard.release();
> return __result;
> }
> @@ -1112,7 +1112,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _UninitDestroyGuard<_ForwardIterator> __guard(__result);
> for (; __n > 0; --__n, (void) ++__first, ++__result)
> - std::_Construct(std::__addressof(*__result), *__first);
> + std::_Construct(std::addressof(*__result), *__first);
> __guard.release();
> return {__first, __result};
> }
> @@ -1276,11 +1276,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> noexcept(noexcept(std::allocator_traits<_Allocator>::construct(__alloc,
> __dest, std::move(*__orig)))
> && noexcept(std::allocator_traits<_Allocator>::destroy(
> - __alloc, std::__addressof(*__orig))))
> + __alloc, std::addressof(*__orig))))
> {
> typedef std::allocator_traits<_Allocator> __traits;
> __traits::construct(__alloc, __dest, std::move(*__orig));
> - __traits::destroy(__alloc, std::__addressof(*__orig));
> + __traits::destroy(__alloc, std::addressof(*__orig));
> }
>
> // This class may be specialized for specific types.
> @@ -1308,8 +1308,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> "relocation is only possible for values of the same type");
> _ForwardIterator __cur = __result;
> for (; __first != __last; ++__first, (void)++__cur)
> - std::__relocate_object_a(std::__addressof(*__cur),
> - std::__addressof(*__first), __alloc);
> + std::__relocate_object_a(std::addressof(*__cur),
> + std::addressof(*__first), __alloc);
> return __cur;
> }
>
> --
> 2.49.0
>
>
