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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___MEMORY_UNIQUE_TEMPORARY_BUFFER_H
#define _LIBCPP___MEMORY_UNIQUE_TEMPORARY_BUFFER_H
#include <__assert>
#include <__config>
#include <__cstddef/ptrdiff_t.h>
#include <__memory/allocator.h>
#include <__memory/unique_ptr.h>
#include <__new/allocate.h>
#include <__new/global_new_delete.h>
#include <__type_traits/is_constant_evaluated.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp>
struct __temporary_buffer_deleter {
ptrdiff_t __count_; // ignored in non-constant evaluation
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __temporary_buffer_deleter() _NOEXCEPT : __count_(0) {}
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_CONSTEXPR explicit __temporary_buffer_deleter(ptrdiff_t __count) _NOEXCEPT : __count_(__count) {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void operator()(_Tp* __ptr) _NOEXCEPT {
if (__libcpp_is_constant_evaluated()) {
allocator<_Tp>().deallocate(__ptr, __count_);
return;
}
std::__libcpp_deallocate_unsized<_Tp>(__ptr);
}
};
template <class _Tp>
using __unique_temporary_buffer _LIBCPP_NODEBUG = unique_ptr<_Tp, __temporary_buffer_deleter<_Tp> >;
template <class _Tp>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_NO_CFI _LIBCPP_CONSTEXPR_SINCE_CXX23 __unique_temporary_buffer<_Tp>
__allocate_unique_temporary_buffer(ptrdiff_t __count) {
using __deleter_type = __temporary_buffer_deleter<_Tp>;
using __unique_buffer_type = __unique_temporary_buffer<_Tp>;
if (__libcpp_is_constant_evaluated()) {
return __unique_buffer_type(allocator<_Tp>().allocate(__count), __deleter_type(__count));
}
_Tp* __ptr = nullptr;
const ptrdiff_t __max_count =
(~ptrdiff_t(0) ^ ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1))) / sizeof(_Tp);
if (__count > __max_count)
__count = __max_count;
while (__count > 0) {
#if _LIBCPP_HAS_ALIGNED_ALLOCATION
if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp))) {
align_val_t __al = align_val_t(_LIBCPP_ALIGNOF(_Tp));
__ptr = static_cast<_Tp*>(::operator new(__count * sizeof(_Tp), __al, nothrow));
} else {
__ptr = static_cast<_Tp*>(::operator new(__count * sizeof(_Tp), nothrow));
}
#else
if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp))) {
// Since aligned operator new is unavailable, constructs an empty buffer rather than one with invalid alignment.
return __unique_buffer_type();
}
__ptr = static_cast<_Tp*>(::operator new(__count * sizeof(_Tp), nothrow));
#endif
if (__ptr) {
break;
}
__count /= 2;
}
return __unique_buffer_type(__ptr, __deleter_type(__count));
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___MEMORY_UNIQUE_TEMPORARY_BUFFER_H
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