| //===----------------------------------------------------------------------===// |
| // |
| // 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___ALGORITHM_COPY_MOVE_COMMON_H |
| #define _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H |
| |
| #include <__algorithm/iterator_operations.h> |
| #include <__algorithm/unwrap_iter.h> |
| #include <__algorithm/unwrap_range.h> |
| #include <__config> |
| #include <__iterator/iterator_traits.h> |
| #include <__memory/pointer_traits.h> |
| #include <__type_traits/enable_if.h> |
| #include <__type_traits/is_always_bitcastable.h> |
| #include <__type_traits/is_constant_evaluated.h> |
| #include <__type_traits/is_copy_constructible.h> |
| #include <__type_traits/is_trivially_assignable.h> |
| #include <__type_traits/is_trivially_copyable.h> |
| #include <__type_traits/is_volatile.h> |
| #include <__utility/move.h> |
| #include <__utility/pair.h> |
| #include <cstddef> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| // Type traits. |
| |
| template <class _From, class _To> |
| struct __can_lower_copy_assignment_to_memmove { |
| static const bool value = |
| // If the types are always bitcastable, it's valid to do a bitwise copy between them. |
| __is_always_bitcastable<_From, _To>::value && |
| // Reject conversions that wouldn't be performed by the regular built-in assignment (e.g. between arrays). |
| is_trivially_assignable<_To&, const _From&>::value && |
| // `memmove` doesn't accept `volatile` pointers, make sure the optimization SFINAEs away in that case. |
| !is_volatile<_From>::value && |
| !is_volatile<_To>::value; |
| }; |
| |
| template <class _From, class _To> |
| struct __can_lower_move_assignment_to_memmove { |
| static const bool value = |
| __is_always_bitcastable<_From, _To>::value && |
| is_trivially_assignable<_To&, _From&&>::value && |
| !is_volatile<_From>::value && |
| !is_volatile<_To>::value; |
| }; |
| |
| // `memmove` algorithms implementation. |
| |
| template <class _In, class _Out> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*> |
| __copy_trivial_impl(_In* __first, _In* __last, _Out* __result) { |
| const size_t __n = static_cast<size_t>(__last - __first); |
| ::__builtin_memmove(__result, __first, __n * sizeof(_Out)); |
| |
| return std::make_pair(__last, __result + __n); |
| } |
| |
| template <class _In, class _Out> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*> |
| __copy_backward_trivial_impl(_In* __first, _In* __last, _Out* __result) { |
| const size_t __n = static_cast<size_t>(__last - __first); |
| __result -= __n; |
| |
| ::__builtin_memmove(__result, __first, __n * sizeof(_Out)); |
| |
| return std::make_pair(__last, __result); |
| } |
| |
| // Iterator unwrapping and dispatching to the correct overload. |
| |
| template <class _F1, class _F2> |
| struct __overload : _F1, _F2 { |
| using _F1::operator(); |
| using _F2::operator(); |
| }; |
| |
| template <class _InIter, class _Sent, class _OutIter, class = void> |
| struct __can_rewrap : false_type {}; |
| |
| template <class _InIter, class _Sent, class _OutIter> |
| struct __can_rewrap<_InIter, |
| _Sent, |
| _OutIter, |
| // Note that sentinels are always copy-constructible. |
| __enable_if_t< is_copy_constructible<_InIter>::value && |
| is_copy_constructible<_OutIter>::value > > : true_type {}; |
| |
| template <class _Algorithm, |
| class _InIter, |
| class _Sent, |
| class _OutIter, |
| __enable_if_t<__can_rewrap<_InIter, _Sent, _OutIter>::value, int> = 0> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter> |
| __unwrap_and_dispatch(_InIter __first, _Sent __last, _OutIter __out_first) { |
| auto __range = std::__unwrap_range(__first, std::move(__last)); |
| auto __result = _Algorithm()(std::move(__range.first), std::move(__range.second), std::__unwrap_iter(__out_first)); |
| return std::make_pair(std::__rewrap_range<_Sent>(std::move(__first), std::move(__result.first)), |
| std::__rewrap_iter(std::move(__out_first), std::move(__result.second))); |
| } |
| |
| template <class _Algorithm, |
| class _InIter, |
| class _Sent, |
| class _OutIter, |
| __enable_if_t<!__can_rewrap<_InIter, _Sent, _OutIter>::value, int> = 0> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter> |
| __unwrap_and_dispatch(_InIter __first, _Sent __last, _OutIter __out_first) { |
| return _Algorithm()(std::move(__first), std::move(__last), std::move(__out_first)); |
| } |
| |
| template <class _IterOps, class _InValue, class _OutIter, class = void> |
| struct __can_copy_without_conversion : false_type {}; |
| |
| template <class _IterOps, class _InValue, class _OutIter> |
| struct __can_copy_without_conversion< |
| _IterOps, |
| _InValue, |
| _OutIter, |
| __enable_if_t<is_same<_InValue, typename _IterOps::template __value_type<_OutIter> >::value> > : true_type {}; |
| |
| template <class _AlgPolicy, |
| class _NaiveAlgorithm, |
| class _OptimizedAlgorithm, |
| class _InIter, |
| class _Sent, |
| class _OutIter> |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter> |
| __dispatch_copy_or_move(_InIter __first, _Sent __last, _OutIter __out_first) { |
| #ifdef _LIBCPP_COMPILER_GCC |
| // GCC doesn't support `__builtin_memmove` during constant evaluation. |
| if (__libcpp_is_constant_evaluated()) { |
| return std::__unwrap_and_dispatch<_NaiveAlgorithm>(std::move(__first), std::move(__last), std::move(__out_first)); |
| } |
| #else |
| // In Clang, `__builtin_memmove` only supports fully trivially copyable types (just having trivial copy assignment is |
| // insufficient). Also, conversions are not supported. |
| if (__libcpp_is_constant_evaluated()) { |
| using _InValue = typename _IterOps<_AlgPolicy>::template __value_type<_InIter>; |
| if (!is_trivially_copyable<_InValue>::value || |
| !__can_copy_without_conversion<_IterOps<_AlgPolicy>, _InValue, _OutIter>::value) { |
| return std::__unwrap_and_dispatch<_NaiveAlgorithm>(std::move(__first), std::move(__last), std::move(__out_first)); |
| } |
| } |
| #endif // _LIBCPP_COMPILER_GCC |
| |
| using _Algorithm = __overload<_NaiveAlgorithm, _OptimizedAlgorithm>; |
| return std::__unwrap_and_dispatch<_Algorithm>(std::move(__first), std::move(__last), std::move(__out_first)); |
| } |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H |