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PR libstdc++/80285 optimize std::make_shared for -fno-rtti

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PR libstdc++/80285
	* include/bits/shared_ptr_base.h (_Sp_make_shared_tag::_S_ti): Define
	function to get unique fake std::type_info reference.
	(_Sp_counted_ptr_inplace::_M_get_deleter) [!__cpp_rtti]: Compare to
	_S_ti() fake reference.
	(__shared_ptr(_Sp_make_shared_tag, const Alloc&, Args&&...)): Share
	single implementation with or without RTTI enable.
	[!__cpp_rtti]: Pass fake reference to _M_get_deleter.
	* testsuite/20_util/shared_ptr/creation/alloc.cc: Change expected
	allocation and deallocation counts.
	* testsuite/20_util/shared_ptr/creation/single_allocation.cc: New.
	* testsuite/20_util/shared_ptr/creation/single_allocation_no_rtti.cc:
	New.

From-SVN: r247905
This commit is contained in:
Jonathan Wakely 2017-05-11 14:21:07 +01:00 committed by Jonathan Wakely
parent 29b871ec5e
commit f8cba3aaae
5 changed files with 158 additions and 39 deletions
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16
libstdc++-v3/ChangeLog
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@ -1,3 +1,19 @@
2017-05-11 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/80285
* include/bits/shared_ptr_base.h (_Sp_make_shared_tag::_S_ti): Define
function to get unique fake std::type_info reference.
(_Sp_counted_ptr_inplace::_M_get_deleter) [!__cpp_rtti]: Compare to
_S_ti() fake reference.
(__shared_ptr(_Sp_make_shared_tag, const Alloc&, Args&&...)): Share
single implementation with or without RTTI enable.
[!__cpp_rtti]: Pass fake reference to _M_get_deleter.
* testsuite/20_util/shared_ptr/creation/alloc.cc: Change expected
allocation and deallocation counts.
* testsuite/20_util/shared_ptr/creation/single_allocation.cc: New.
* testsuite/20_util/shared_ptr/creation/single_allocation_no_rtti.cc:
New.
2017-05-10 François Dumont <fdumont@gcc.gnu.org>
Bump version namespace.

64
libstdc++-v3/include/bits/shared_ptr_base.h
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@ -68,6 +68,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#pragma GCC diagnostic pop
#endif
#if !__cpp_rtti
class type_info;
#endif
/**
* @brief Exception possibly thrown by @c shared_ptr.
* @ingroup exceptions
@ -498,7 +502,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// helpers for make_shared / allocate_shared
struct _Sp_make_shared_tag { };
struct _Sp_make_shared_tag
{
#if !__cpp_rtti
private:
template<typename _Tp, _Lock_policy _Lp>
friend class __shared_ptr;
template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
friend class _Sp_counted_ptr_inplace;
static const type_info&
_S_ti() noexcept
{
static constexpr _Sp_make_shared_tag __tag;
return reinterpret_cast<const type_info&>(__tag);
}
#endif
};
template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
@ -551,8 +571,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
#if __cpp_rtti
if (__ti == typeid(_Sp_make_shared_tag))
return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
#else
if (&__ti == &_Sp_make_shared_tag::_S_ti())
#endif
return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
return nullptr;
}
@ -1295,7 +1317,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const
{ return _M_refcount._M_less(__rhs._M_refcount); }
#if __cpp_rtti
protected:
// This constructor is non-standard, it is used by allocate_shared.
template<typename _Alloc, typename... _Args>
@ -1306,43 +1327,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
// _M_ptr needs to point to the newly constructed object.
// This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
#if __cpp_rtti
void* __p = _M_refcount._M_get_deleter(typeid(__tag));
#else
void* __p = _M_refcount._M_get_deleter(_Sp_make_shared_tag::_S_ti());
#endif
_M_ptr = static_cast<_Tp*>(__p);
_M_enable_shared_from_this_with(_M_ptr);
}
#else
template<typename _Alloc>
struct _Deleter
{
void operator()(typename _Alloc::value_type* __ptr)
{
__allocated_ptr<_Alloc> __guard{ _M_alloc, __ptr };
allocator_traits<_Alloc>::destroy(_M_alloc, __guard.get());
}
_Alloc _M_alloc;
};
template<typename _Alloc, typename... _Args>
__shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
_Args&&... __args)
: _M_ptr(), _M_refcount()
{
typedef typename allocator_traits<_Alloc>::template
rebind_traits<typename std::remove_cv<_Tp>::type> __traits;
_Deleter<typename __traits::allocator_type> __del = { __a };
auto __guard = std::__allocate_guarded(__del._M_alloc);
auto __ptr = __guard.get();
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2070. allocate_shared should use allocator_traits<A>::construct
__traits::construct(__del._M_alloc, __ptr,
std::forward<_Args>(__args)...);
__guard = nullptr;
__shared_count<_Lp> __count(__ptr, __del, __del._M_alloc);
_M_refcount._M_swap(__count);
_M_ptr = __ptr;
_M_enable_shared_from_this_with(_M_ptr);
}
#endif
template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
typename... _Args>

6
libstdc++-v3/testsuite/20_util/shared_ptr/creation/alloc.cc
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@ -63,7 +63,7 @@ test01()
VERIFY( p1.get() != 0 );
VERIFY( p1.use_count() == 1 );
VERIFY( A::ctor_count == 1 );
VERIFY( tracker_allocator_counter::get_allocation_count() > 0 );
VERIFY( tracker_allocator_counter::get_allocation_count() > sizeof(A) );
}
VERIFY( A::ctor_count == A::dtor_count );
VERIFY( tracker_allocator_counter::get_allocation_count()
@ -79,12 +79,12 @@ test02()
p1 = std::allocate_shared<A>(tracker_allocator<A>(), 1);
VERIFY( A::ctor_count == 1 );
VERIFY( tracker_allocator_counter::get_allocation_count() > 0 );
VERIFY( tracker_allocator_counter::get_allocation_count() > sizeof(A) );
p1 = std::allocate_shared<A>(tracker_allocator<A>(), 1, 2.0);
VERIFY( A::ctor_count == 2 );
VERIFY( A::dtor_count == 1 );
VERIFY( tracker_allocator_counter::get_deallocation_count() > 0 );
VERIFY( tracker_allocator_counter::get_deallocation_count() > sizeof(A) );
p1 = std::allocate_shared<A>(tracker_allocator<A>(), 1, 2.0, '3');
VERIFY( A::ctor_count == 3 );

55
libstdc++-v3/testsuite/20_util/shared_ptr/creation/single_allocation.cc Normal file
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@ -0,0 +1,55 @@
// 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
// <http://www.gnu.org/licenses/>.
// { dg-do run { target c++11 } }
#include <memory>
#include <testsuite_hooks.h>
int counter = 0;
template<typename T>
struct Alloc : std::allocator<T>
{
template<typename U>
struct rebind { using other = Alloc<U>; };
Alloc() = default;
template<typename U>
Alloc(const Alloc<U>&) { }
T* allocate(std::size_t n)
{
++counter;
return std::allocator<T>::allocate(n);
}
};
void
test01()
{
std::allocate_shared<int>(Alloc<int>());
VERIFY( counter == 1 );
}
int
main()
{
test01();
}

56
libstdc++-v3/testsuite/20_util/shared_ptr/creation/single_allocation_no_rtti.cc Normal file
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@ -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
// <http://www.gnu.org/licenses/>.
// { dg-options "-fno-rtti" }
// { dg-do run { target c++11 } }
#include <memory>
#include <testsuite_hooks.h>
int counter = 0;
template<typename T>
struct Alloc : std::allocator<T>
{
template<typename U>
struct rebind { using other = Alloc<U>; };
Alloc() = default;
template<typename U>
Alloc(const Alloc<U>&) { }
T* allocate(std::size_t n)
{
++counter;
return std::allocator<T>::allocate(n);
}
};
void
test01()
{
std::allocate_shared<int>(Alloc<int>());
VERIFY( counter == 1 );
}
int
main()
{
test01();
}