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libstdc++: Use RAII in std::vector::_M_default_append

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Similar to r14-2052-gdd2eb972a5b063, replace the try-block with RAII
types for deallocating storage and destroying elements.

libstdc++-v3/ChangeLog:

	* include/bits/vector.tcc (_M_default_append): Replace try-block
	with RAII types.
This commit is contained in:
Jonathan Wakely 2023-06-20 13:39:29 +01:00
parent 49f2b325ec
commit 4870a18ac2
1 changed files with 59 additions and 32 deletions
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91
libstdc++-v3/include/bits/vector.tcc
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@ -704,47 +704,74 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
const size_type __len =
_M_check_len(__n, "vector::_M_default_append");
pointer __new_start(this->_M_allocate(__len));
// RAII guard for allocated storage.
struct _Guard
{
pointer _M_storage; // Storage to deallocate
size_type _M_len;
_Tp_alloc_type& _M_alloc;
_GLIBCXX20_CONSTEXPR
_Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
: _M_storage(__s), _M_len(__l), _M_alloc(__a)
{ }
_GLIBCXX20_CONSTEXPR
~_Guard()
{
if (_M_storage)
__gnu_cxx::__alloc_traits<_Tp_alloc_type>::
deallocate(_M_alloc, _M_storage, _M_len);
}
private:
_Guard(const _Guard&);
};
_Guard __guard(__new_start, __len, _M_impl);
std::__uninitialized_default_n_a(__new_start + __size, __n,
_M_get_Tp_allocator());
if _GLIBCXX17_CONSTEXPR (_S_use_relocate())
{
__try
{
std::__uninitialized_default_n_a(__new_start + __size,
__n, _M_get_Tp_allocator());
}
__catch(...)
{
_M_deallocate(__new_start, __len);
__throw_exception_again;
}
_S_relocate(__old_start, __old_finish,
__new_start, _M_get_Tp_allocator());
}
else
{
pointer __destroy_from = pointer();
__try
{
std::__uninitialized_default_n_a(__new_start + __size,
__n, _M_get_Tp_allocator());
__destroy_from = __new_start + __size;
std::__uninitialized_move_if_noexcept_a(
__old_start, __old_finish,
__new_start, _M_get_Tp_allocator());
}
__catch(...)
{
if (__destroy_from)
std::_Destroy(__destroy_from, __destroy_from + __n,
_M_get_Tp_allocator());
_M_deallocate(__new_start, __len);
__throw_exception_again;
}
std::_Destroy(__old_start, __old_finish,
_M_get_Tp_allocator());
// RAII type to destroy initialized elements.
struct _Guard_elts
{
pointer _M_first, _M_last; // Elements to destroy
_Tp_alloc_type& _M_alloc;
_GLIBCXX20_CONSTEXPR
_Guard_elts(pointer __first, size_type __n,
_Tp_alloc_type& __a)
: _M_first(__first), _M_last(__first + __n), _M_alloc(__a)
{ }
_GLIBCXX20_CONSTEXPR
~_Guard_elts()
{ std::_Destroy(_M_first, _M_last, _M_alloc); }
private:
_Guard_elts(const _Guard_elts&);
};
_Guard_elts __guard_elts(__new_start + __size, __n, _M_impl);
std::__uninitialized_move_if_noexcept_a(
__old_start, __old_finish, __new_start,
_M_get_Tp_allocator());
__guard_elts._M_first = __old_start;
__guard_elts._M_last = __old_finish;
}
_GLIBCXX_ASAN_ANNOTATE_REINIT;
_M_deallocate(__old_start,
this->_M_impl._M_end_of_storage - __old_start);
__guard._M_storage = __old_start;
__guard._M_len = this->_M_impl._M_end_of_storage - __old_start;
this->_M_impl._M_start = __new_start;
this->_M_impl._M_finish = __new_start + __size + __n;
this->_M_impl._M_end_of_storage = __new_start + __len;