From 2ae27b7076907aa872ffda98c4cb83b3dad30b40 Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Wed, 18 Jan 2017 18:36:45 +0000 Subject: [PATCH] PR69301 don't assume atomic can default construct T PR libstdc++/69301 * include/std/atomic (atomic::load, atomic::exchange): Use aligned buffer instead of default-initialized variable. * testsuite/29_atomics/atomic/69301.cc: New test. * include/experimental/memory (observer_ptr::release): Use reserved name. * include/ext/pointer.h (_Pointer_adapter::operator++(int)) (_Pointer_adapter::operator--(int)): Likewise. From-SVN: r244588 --- libstdc++-v3/ChangeLog | 9 ++++ libstdc++-v3/include/experimental/memory | 4 +- libstdc++-v3/include/ext/pointer.h | 8 ++-- libstdc++-v3/include/std/atomic | 28 +++++++----- libstdc++-v3/testsuite/29_atomics/atomic/69301.cc | 56 +++++++++++++++++++++++ 5 files changed, 87 insertions(+), 18 deletions(-) create mode 100644 libstdc++-v3/testsuite/29_atomics/atomic/69301.cc diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 6b51357..9af3b9f 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,14 @@ 2017-01-18 Jonathan Wakely + PR libstdc++/69301 + * include/std/atomic (atomic::load, atomic::exchange): Use + aligned buffer instead of default-initialized variable. + * testsuite/29_atomics/atomic/69301.cc: New test. + * include/experimental/memory (observer_ptr::release): Use reserved + name. + * include/ext/pointer.h (_Pointer_adapter::operator++(int)) + (_Pointer_adapter::operator--(int)): Likewise. + PR libstdc++/68925 * include/experimental/random (randint): Use temporary instead of thread_local static. diff --git a/libstdc++-v3/include/experimental/memory b/libstdc++-v3/include/experimental/memory index 239afb9..7467674 100644 --- a/libstdc++-v3/include/experimental/memory +++ b/libstdc++-v3/include/experimental/memory @@ -124,9 +124,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION constexpr __pointer release() noexcept { - __pointer tmp = get(); + __pointer __tmp = get(); reset(); - return tmp; + return __tmp; } constexpr void diff --git a/libstdc++-v3/include/ext/pointer.h b/libstdc++-v3/include/ext/pointer.h index f4ba325..8432da0 100644 --- a/libstdc++-v3/include/ext/pointer.h +++ b/libstdc++-v3/include/ext/pointer.h @@ -449,9 +449,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION inline _Pointer_adapter operator++(int) { - _Pointer_adapter tmp(*this); + _Pointer_adapter __tmp(*this); _Storage_policy::set(_Storage_policy::get() + 1); - return tmp; + return __tmp; } inline _Pointer_adapter& @@ -464,9 +464,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION inline _Pointer_adapter operator--(int) { - _Pointer_adapter tmp(*this); + _Pointer_adapter __tmp(*this); _Storage_policy::set(_Storage_policy::get() - 1); - return tmp; + return __tmp; } }; // class _Pointer_adapter diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic index 7b169e5..5b252a4 100644 --- a/libstdc++-v3/include/std/atomic +++ b/libstdc++-v3/include/std/atomic @@ -245,36 +245,40 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _Tp load(memory_order __m = memory_order_seq_cst) const noexcept { - _Tp tmp; - __atomic_load(std::__addressof(_M_i), std::__addressof(tmp), __m); - return tmp; + alignas(_Tp) unsigned char __buf[sizeof(_Tp)]; + _Tp* __ptr = reinterpret_cast<_Tp*>(__buf); + __atomic_load(std::__addressof(_M_i), __ptr, __m); + return *__ptr; } _Tp load(memory_order __m = memory_order_seq_cst) const volatile noexcept { - _Tp tmp; - __atomic_load(std::__addressof(_M_i), std::__addressof(tmp), __m); - return tmp; + alignas(_Tp) unsigned char __buf[sizeof(_Tp)]; + _Tp* __ptr = reinterpret_cast<_Tp*>(__buf); + __atomic_load(std::__addressof(_M_i), __ptr, __m); + return *__ptr; } _Tp exchange(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept { - _Tp tmp; + alignas(_Tp) unsigned char __buf[sizeof(_Tp)]; + _Tp* __ptr = reinterpret_cast<_Tp*>(__buf); __atomic_exchange(std::__addressof(_M_i), std::__addressof(__i), - std::__addressof(tmp), __m); - return tmp; + __ptr, __m); + return *__ptr; } _Tp exchange(_Tp __i, memory_order __m = memory_order_seq_cst) volatile noexcept { - _Tp tmp; + alignas(_Tp) unsigned char __buf[sizeof(_Tp)]; + _Tp* __ptr = reinterpret_cast<_Tp*>(__buf); __atomic_exchange(std::__addressof(_M_i), std::__addressof(__i), - std::__addressof(tmp), __m); - return tmp; + __ptr, __m); + return *__ptr; } bool diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/69301.cc b/libstdc++-v3/testsuite/29_atomics/atomic/69301.cc new file mode 100644 index 0000000..1af3652 --- /dev/null +++ b/libstdc++-v3/testsuite/29_atomics/atomic/69301.cc @@ -0,0 +1,56 @@ +// Copyright (C) 2017 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// . + +// { dg-do run { target c++11 } } + +#include +#include + +struct NonDefaultConstructible +{ + NonDefaultConstructible(int i) : val(i) { } + int val; +}; + +template class std::atomic; + +void +test01() +{ + std::atomic a(1); + const auto n1 = a.exchange(2); + VERIFY( n1.val == 1 ); + const auto n2 = a.load(); + VERIFY( n2.val == 2 ); +} + +void +test02() +{ + volatile std::atomic a(1); + const auto n1 = a.exchange(2); + VERIFY( n1.val == 1 ); + const auto n2 = a.load(); + VERIFY( n2.val == 2 ); +} + +int +main() +{ + test01(); + test02(); +} -- 2.7.4