Tested x86_64-linux, pushed to trunk.
-- >8 --
This class template and partial specialization were added 15 years ago
to optimize allocator equality comparisons in std::list. I think it's
safe to assume that GCC is now capable of optimizing an inline
operator!= that just returns false at least as well as an inline member
function that just returns false.
libstdc++-v3/ChangeLog:
* include/bits/allocator.h (__alloc_neq): Remove.
* include/bits/stl_list.h (list::_M_check_equal_allocators):
Compare allocators directly, without __alloc_neq.
---
libstdc++-v3/include/bits/allocator.h | 17 -----------------
libstdc++-v3/include/bits/stl_list.h | 5 ++---
2 files changed, 2 insertions(+), 20 deletions(-)
diff --git a/libstdc++-v3/include/bits/allocator.h
b/libstdc++-v3/include/bits/allocator.h
index 28abf13eba9..c39166e24fe 100644
--- a/libstdc++-v3/include/bits/allocator.h
+++ b/libstdc++-v3/include/bits/allocator.h
@@ -298,23 +298,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
- // Optimize for stateless allocators.
- template<typename _Alloc, bool = __is_empty(_Alloc)>
- struct __alloc_neq
- {
- static bool
- _S_do_it(const _Alloc&, const _Alloc&)
- { return false; }
- };
-
- template<typename _Alloc>
- struct __alloc_neq<_Alloc, false>
- {
- static bool
- _S_do_it(const _Alloc& __one, const _Alloc& __two)
- { return __one != __two; }
- };
-
#if __cplusplus >= 201103L
template<typename _Tp, bool
= __or_<is_copy_constructible<typename _Tp::value_type>,
diff --git a/libstdc++-v3/include/bits/stl_list.h
b/libstdc++-v3/include/bits/stl_list.h
index b8bd46191fc..a73ca60df5a 100644
--- a/libstdc++-v3/include/bits/stl_list.h
+++ b/libstdc++-v3/include/bits/stl_list.h
@@ -2026,10 +2026,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
// To implement the splice (and merge) bits of N1599.
void
- _M_check_equal_allocators(list& __x) _GLIBCXX_NOEXCEPT
+ _M_check_equal_allocators(const list& __x) _GLIBCXX_NOEXCEPT
{
- if (std::__alloc_neq<typename _Base::_Node_alloc_type>::
- _S_do_it(_M_get_Node_allocator(), __x._M_get_Node_allocator()))
+ if (_M_get_Node_allocator() != __x._M_get_Node_allocator())
__builtin_abort();
}
--
2.37.3
