From e3b557809604d036af6e00c60f012c2025b59a5e Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Sat, 11 Feb 2023 13:38:04 +0100 Subject: Vendor import of llvm-project main llvmorg-16-init-18548-gb0daacf58f41, the last commit before the upstream release/17.x branch was created. --- libcxx/include/__algorithm/copy_move_common.h | 163 ++++++++++++++++++++++++++ 1 file changed, 163 insertions(+) create mode 100644 libcxx/include/__algorithm/copy_move_common.h (limited to 'libcxx/include/__algorithm/copy_move_common.h') diff --git a/libcxx/include/__algorithm/copy_move_common.h b/libcxx/include/__algorithm/copy_move_common.h new file mode 100644 index 000000000000..b88c14911b9b --- /dev/null +++ b/libcxx/include/__algorithm/copy_move_common.h @@ -0,0 +1,163 @@ +//===----------------------------------------------------------------------===// +// +// 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 + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_BEGIN_NAMESPACE_STD + +// Type traits. + +template +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 +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 +_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(__last - __first); + ::__builtin_memmove(__result, __first, __n * sizeof(_Out)); + + return std::make_pair(__last, __result + __n); +} + +template +_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(__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 +struct __overload : _F1, _F2 { + using _F1::operator(); + using _F2::operator(); +}; + +template +struct __can_rewrap : false_type {}; + +template +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 ::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 ::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 +struct __can_copy_without_conversion : false_type {}; + +template +struct __can_copy_without_conversion< + _IterOps, + _InValue, + _OutIter, + __enable_if_t >::value> > : true_type {}; + +template +_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 -- cgit v1.2.3