From 1cc56f079e60fc60df904e443784ad6e7081300c Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Wed, 13 Jun 2018 16:14:48 +0100 Subject: [PATCH] PR libstdc++/86127 avoid unnecessary allocator conversions There is no need to use an allocator of the correct value_type when calling allocator_traits::construct and allocator_traits::destroy. The existing node allocator can be used, instead of constructing a new allocator object every time. There's also no benefit to using __gnu_cxx::__alloc_traits instead of std::allocator_traits to get the pointer and const_pointer types. std::forward_list is only available for C++11 and later, when std::allocator_traits is available too. PR libstdc++/86127 * include/bits/forward_list.h (_Fwd_list_base::_Tp_alloc_type): Remove unused typedef. (_Fwd_list_base::_Node_alloc_traits): Use allocator_traits instead of __gnu_cxx::__alloc_traits. (_Fwd_list_base::_M_create_node, _Fwd_list_base::_M_erase_after): Use node allocator to create and destroy elements. (forward_list::_Tp_alloc_type): Remove unused typedef. (forward_list::_Alloc_traits): Use allocator_traits instead of __gnu_cxx::__alloc_traits. From-SVN: r261554 --- libstdc++-v3/ChangeLog | 13 +++++++++++++ libstdc++-v3/include/bits/forward_list.h | 11 ++++------- libstdc++-v3/include/bits/forward_list.tcc | 8 ++++---- 3 files changed, 21 insertions(+), 11 deletions(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index c8510608354..9f33999563b 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,16 @@ +2018-06-13 Jonathan Wakely + + PR libstdc++/86127 + * include/bits/forward_list.h (_Fwd_list_base::_Tp_alloc_type): Remove + unused typedef. + (_Fwd_list_base::_Node_alloc_traits): Use allocator_traits instead of + __gnu_cxx::__alloc_traits. + (_Fwd_list_base::_M_create_node, _Fwd_list_base::_M_erase_after): + Use node allocator to create and destroy elements. + (forward_list::_Tp_alloc_type): Remove unused typedef. + (forward_list::_Alloc_traits): Use allocator_traits instead of + __gnu_cxx::__alloc_traits. + 2018-06-13 François Dumont * include/debug/debug.h (__glibcxx_requires_can_increment_range): New. diff --git a/libstdc++-v3/include/bits/forward_list.h b/libstdc++-v3/include/bits/forward_list.h index b40256bd104..8c4c074e454 100644 --- a/libstdc++-v3/include/bits/forward_list.h +++ b/libstdc++-v3/include/bits/forward_list.h @@ -289,7 +289,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER struct _Fwd_list_base { protected: - typedef __alloc_rebind<_Alloc, _Tp> _Tp_alloc_type; typedef __alloc_rebind<_Alloc, _Fwd_list_node<_Tp>> _Node_alloc_type; typedef __gnu_cxx::__alloc_traits<_Node_alloc_type> _Node_alloc_traits; @@ -363,11 +362,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _Node* __node = this->_M_get_node(); __try { - _Tp_alloc_type __a(_M_get_Node_allocator()); - typedef allocator_traits<_Tp_alloc_type> _Alloc_traits; ::new ((void*)__node) _Node; - _Alloc_traits::construct(__a, __node->_M_valptr(), - std::forward<_Args>(__args)...); + _Node_alloc_traits::construct(_M_get_Node_allocator(), + __node->_M_valptr(), + std::forward<_Args>(__args)...); } __catch(...) { @@ -437,10 +435,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER typedef _Fwd_list_base<_Tp, _Alloc> _Base; typedef _Fwd_list_node<_Tp> _Node; typedef _Fwd_list_node_base _Node_base; - typedef typename _Base::_Tp_alloc_type _Tp_alloc_type; typedef typename _Base::_Node_alloc_type _Node_alloc_type; typedef typename _Base::_Node_alloc_traits _Node_alloc_traits; - typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Alloc_traits; + typedef allocator_traits<__alloc_rebind<_Alloc, _Tp>> _Alloc_traits; public: // types: diff --git a/libstdc++-v3/include/bits/forward_list.tcc b/libstdc++-v3/include/bits/forward_list.tcc index 3e12cd531d4..b41fbbb52f2 100644 --- a/libstdc++-v3/include/bits/forward_list.tcc +++ b/libstdc++-v3/include/bits/forward_list.tcc @@ -65,8 +65,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER { _Node* __curr = static_cast<_Node*>(__pos->_M_next); __pos->_M_next = __curr->_M_next; - _Tp_alloc_type __a(_M_get_Node_allocator()); - allocator_traits<_Tp_alloc_type>::destroy(__a, __curr->_M_valptr()); + _Node_alloc_traits::destroy(_M_get_Node_allocator(), + __curr->_M_valptr()); __curr->~_Node(); _M_put_node(__curr); return __pos->_M_next; @@ -83,8 +83,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER { _Node* __temp = __curr; __curr = static_cast<_Node*>(__curr->_M_next); - _Tp_alloc_type __a(_M_get_Node_allocator()); - allocator_traits<_Tp_alloc_type>::destroy(__a, __temp->_M_valptr()); + _Node_alloc_traits::destroy(_M_get_Node_allocator(), + __temp->_M_valptr()); __temp->~_Node(); _M_put_node(__temp); } -- 2.30.2