diff options
6 files changed, 258 insertions, 6 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 575e52a70b6..fe43ed27f67 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,19 @@ +2018-10-25 Jonathan Wakely <jwakely@redhat.com> + + PR libstdc++/87749 + * include/bits/basic_string.h [_GLIBCXX_USE_CXX11_ABI] + (basic_string::operator=(basic_string&&)): For short strings copy the + buffer inline. Only fall back to using assign(const basic_string&) to + do a deep copy when reallocation is needed. + * testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc: + New test. + * testsuite/21_strings/basic_string/modifiers/assign/char/ + move_assign_optim.cc: New test. + * testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc: + New test. + * testsuite/21_strings/basic_string/modifiers/assign/wchar_t/ + move_assign_optim.cc: New test. + 2018-10-25 Marc Glisse <marc.glisse@inria.fr> PR libstdc++/87106 diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h index ba94b51f616..ae6530fcdc9 100644 --- a/libstdc++-v3/include/bits/basic_string.h +++ b/libstdc++-v3/include/bits/basic_string.h @@ -744,20 +744,29 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 // Replace allocator if POCMA is true. std::__alloc_on_move(_M_get_allocator(), __str._M_get_allocator()); - if (!__str._M_is_local() - && (_Alloc_traits::_S_propagate_on_move_assign() - || _Alloc_traits::_S_always_equal())) + if (__str._M_is_local()) + { + // We've always got room for a short string, just copy it. + if (__str.size()) + this->_S_copy(_M_data(), __str._M_data(), __str.size()); + _M_set_length(__str.size()); + } + else if (_Alloc_traits::_S_propagate_on_move_assign() + || _Alloc_traits::_S_always_equal() + || _M_get_allocator() == __str._M_get_allocator()) { + // Just move the allocated pointer, our allocator can free it. pointer __data = nullptr; size_type __capacity; if (!_M_is_local()) { if (_Alloc_traits::_S_always_equal()) { + // __str can reuse our existing storage. __data = _M_data(); __capacity = _M_allocated_capacity; } - else + else // __str can't use it, so free it. _M_destroy(_M_allocated_capacity); } @@ -772,8 +781,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 else __str._M_data(__str._M_local_buf); } - else - assign(__str); + else // Need to do a deep copy + assign(__str); __str.clear(); return *this; } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc new file mode 100644 index 00000000000..ef5f1e708ac --- /dev/null +++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc @@ -0,0 +1,78 @@ +// Copyright (C) 2018 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 +// <http://www.gnu.org/licenses/>. + +// { dg-do run { target c++11 } } + +// PR libstdc++/87749 + +#include <string> +#include <testsuite_hooks.h> + +bool oom = false; + +template<typename T> +struct alloc +{ + using value_type = T; + +#if !_GLIBCXX_USE_CXX11_ABI + using size_type = unsigned long; + using difference_type = long; + using reference = T&; + using const_reference = T&; + using pointer = T*; + using const_pointer = const T*; + template<typename U> + struct rebind { using other = alloc<U>; }; +#endif + + int not_empty = 0; // this makes is_always_equal false + + alloc() = default; + template<typename U> + alloc(const alloc<U>&) { } + + T* allocate(unsigned long n) + { + if (oom) + throw std::bad_alloc(); + return std::allocator<T>().allocate(n); + } + + void deallocate(T* p, unsigned long n) + { + std::allocator<T>().deallocate(p, n); + } +}; + +template<typename T, typename U> +bool operator==(const alloc<T>&, const alloc<U>&) { return true; } + +template<typename T, typename U> +bool operator!=(const alloc<T>&, const alloc<U>&) { return false; } + +int main() +{ + using string = std::basic_string<char, std::char_traits<char>, alloc<char>>; + + string s = "PR libstdc++/87749 a string that is longer than a short string"; + const auto ptr = s.c_str(); + oom = true; + string ss; + ss = std::move(s); // allocators are equal, should not allocate new storage + VERIFY( ss.c_str() == ptr ); +} diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/move_assign_optim.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/move_assign_optim.cc new file mode 100644 index 00000000000..b56bc50e1c1 --- /dev/null +++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/move_assign_optim.cc @@ -0,0 +1,35 @@ +// Copyright (C) 2018 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 +// <http://www.gnu.org/licenses/>. + +// { dg-options "-O1" } +// { dg-do compile { target c++11 } } +// { dg-final { scan-assembler-not "__throw_length_error" } } +// { dg-final { scan-assembler-not "__throw_bad_alloc" } } + +#include <bits/c++config.h> +#undef _GLIBCXX_EXTERN_TEMPLATE +#include <string> + +void +test01(std::string& target, std::string&& source) +{ + // The move assignment operator should be simple enough that the compiler + // can see that it never results in a length_error or bad_alloc exception + // (which would be turned into std::terminate by the noexcept on the + // assignment operator). + target = std::move(source); +} diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc new file mode 100644 index 00000000000..d4062a9e637 --- /dev/null +++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc @@ -0,0 +1,79 @@ +// Copyright (C) 2018 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 +// <http://www.gnu.org/licenses/>. + +// { dg-do run { target c++11 } } + +// PR libstdc++/87749 + +#include <string> +#include <testsuite_hooks.h> + +bool oom = false; + +template<typename T> +struct alloc +{ + using value_type = T; + +#if !_GLIBCXX_USE_CXX11_ABI + using size_type = unsigned long; + using difference_type = long; + using reference = T&; + using const_reference = T&; + using pointer = T*; + using const_pointer = const T*; + template<typename U> + struct rebind { using other = alloc<U>; }; +#endif + + int not_empty = 0; // this makes is_always_equal false + + alloc() = default; + template<typename U> + alloc(const alloc<U>&) { } + + T* allocate(unsigned long n) + { + if (oom) + throw std::bad_alloc(); + return std::allocator<T>().allocate(n); + } + + void deallocate(T* p, unsigned long n) + { + std::allocator<T>().deallocate(p, n); + } +}; + +template<typename T, typename U> +bool operator==(const alloc<T>&, const alloc<U>&) { return true; } + +template<typename T, typename U> +bool operator!=(const alloc<T>&, const alloc<U>&) { return false; } + +int main() +{ + using string + = std::basic_string<wchar_t, std::char_traits<wchar_t>, alloc<wchar_t>>; + + string s = L"PR libstdc++/87749 a string that is longer than a short string"; + const auto ptr = s.c_str(); + oom = true; + string ss; + ss = std::move(s); // allocators are equal, should not allocate new storage + VERIFY( ss.c_str() == ptr ); +} diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/move_assign_optim.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/move_assign_optim.cc new file mode 100644 index 00000000000..f54ad36a5d0 --- /dev/null +++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/move_assign_optim.cc @@ -0,0 +1,35 @@ +// Copyright (C) 2018 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 +// <http://www.gnu.org/licenses/>. + +// { dg-options "-O1" } +// { dg-do compile { target c++11 } } +// { dg-final { scan-assembler-not "__throw_length_error" } } +// { dg-final { scan-assembler-not "__throw_bad_alloc" } } + +#include <bits/c++config.h> +#undef _GLIBCXX_EXTERN_TEMPLATE +#include <string> + +void +test01(std::wstring& target, std::wstring&& source) +{ + // The move assignment operator should be simple enough that the compiler + // can see that it never results in a length_error or bad_alloc exception + // (which would be turned into std::terminate by the noexcept on the + // assignment operator). + target = std::move(source); +} |