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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___ALGORITHM_FIND_H11#define _LIBCPP___ALGORITHM_FIND_H12 13#include <__algorithm/find_segment_if.h>14#include <__algorithm/min.h>15#include <__algorithm/simd_utils.h>16#include <__algorithm/unwrap_iter.h>17#include <__bit/countr.h>18#include <__bit/invert_if.h>19#include <__config>20#include <__cstddef/size_t.h>21#include <__functional/identity.h>22#include <__fwd/bit_reference.h>23#include <__iterator/segmented_iterator.h>24#include <__string/constexpr_c_functions.h>25#include <__type_traits/enable_if.h>26#include <__type_traits/invoke.h>27#include <__type_traits/is_constant_evaluated.h>28#include <__type_traits/is_equality_comparable.h>29#include <__type_traits/is_integral.h>30#include <__type_traits/is_signed.h>31#include <__utility/move.h>32#include <limits>33 34#if _LIBCPP_HAS_WIDE_CHARACTERS35# include <cwchar>36#endif37 38#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)39# pragma GCC system_header40#endif41 42_LIBCPP_PUSH_MACROS43#include <__undef_macros>44 45_LIBCPP_BEGIN_NAMESPACE_STD46 47// generic implementation48template <class _Iter, class _Sent, class _Tp, class _Proj>49_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter50__find_loop(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {51 for (; __first != __last; ++__first)52 if (std::__invoke(__proj, *__first) == __value)53 break;54 return __first;55}56 57template <class _Iter, class _Sent, class _Tp, class _Proj>58_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter59__find(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {60 return std::__find_loop(std::move(__first), std::move(__last), __value, __proj);61}62 63#if _LIBCPP_VECTORIZE_ALGORITHMS64template <class _Tp, class _Up>65[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI66_LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find_vectorized(_Tp* __first, _Tp* __last, _Up __value) {67 if (!__libcpp_is_constant_evaluated()) {68 constexpr size_t __unroll_count = 4;69 constexpr size_t __vec_size = __native_vector_size<_Tp>;70 using __vec = __simd_vector<_Tp, __vec_size>;71 72 auto __orig_first = __first;73 74 auto __values = static_cast<__simd_vector<_Tp, __vec_size>>(__value); // broadcast the value75 while (static_cast<size_t>(__last - __first) >= __unroll_count * __vec_size) [[__unlikely__]] {76 __vec __lhs[__unroll_count];77 78 for (size_t __i = 0; __i != __unroll_count; ++__i)79 __lhs[__i] = std::__load_vector<__vec>(__first + __i * __vec_size);80 81 for (size_t __i = 0; __i != __unroll_count; ++__i) {82 if (auto __cmp_res = __lhs[__i] == __values; std::__any_of(__cmp_res)) {83 auto __offset = __i * __vec_size + std::__find_first_set(__cmp_res);84 return __first + __offset;85 }86 }87 88 __first += __unroll_count * __vec_size;89 }90 91 // check the remaining 0-3 vectors92 while (static_cast<size_t>(__last - __first) >= __vec_size) {93 if (auto __cmp_res = std::__load_vector<__vec>(__first) == __values; std::__any_of(__cmp_res)) {94 return __first + std::__find_first_set(__cmp_res);95 }96 __first += __vec_size;97 }98 99 if (__last - __first == 0)100 return __first;101 102 // Check if we can load elements in front of the current pointer. If that's the case load a vector at103 // (last - vector_size) to check the remaining elements104 if (static_cast<size_t>(__first - __orig_first) >= __vec_size) {105 __first = __last - __vec_size;106 return __first + std::__find_first_set(std::__load_vector<__vec>(__first) == __values);107 }108 }109 110 __identity __proj;111 return std::__find_loop(__first, __last, __value, __proj);112}113#endif114 115#ifndef _LIBCPP_CXX03_LANG116// trivially equality comparable implementations117template <118 class _Tp,119 class _Up,120 class _Proj,121 __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value, int> = 0>122_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {123 if constexpr (sizeof(_Tp) == 1) {124 if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first))125 return __ret;126 return __last;127 }128# if _LIBCPP_HAS_WIDE_CHARACTERS129 else if constexpr (sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t)) {130 if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first))131 return __ret;132 return __last;133 }134# endif135# if _LIBCPP_VECTORIZE_ALGORITHMS136 else if constexpr (is_integral<_Tp>::value) {137 return std::__find_vectorized(__first, __last, __value);138 }139# endif140 else {141 __identity __proj;142 return std::__find_loop(__first, __last, __value, __proj);143 }144}145#endif146 147// TODO: This should also be possible to get right with different signedness148// cast integral types to allow vectorization149template <class _Tp,150 class _Up,151 class _Proj,152 __enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&153 is_integral<_Tp>::value && is_integral<_Up>::value &&154 is_signed<_Tp>::value == is_signed<_Up>::value,155 int> = 0>156_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*157__find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) {158 if (__value < numeric_limits<_Tp>::min() || __value > numeric_limits<_Tp>::max())159 return __last;160 return std::__find(__first, __last, _Tp(__value), __proj);161}162 163// __bit_iterator implementation164template <bool _ToFind, class _Cp, bool _IsConst>165_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>166__find_bool(__bit_iterator<_Cp, _IsConst> __first, typename __size_difference_type_traits<_Cp>::size_type __n) {167 using _It = __bit_iterator<_Cp, _IsConst>;168 using __storage_type = typename _It::__storage_type;169 170 const int __bits_per_word = _It::__bits_per_word;171 // do first partial word172 if (__first.__ctz_ != 0) {173 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);174 __storage_type __dn = std::min(__clz_f, __n);175 __storage_type __m = std::__middle_mask<__storage_type>(__clz_f - __dn, __first.__ctz_);176 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;177 if (__b)178 return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));179 if (__n == __dn)180 return __first + __n;181 __n -= __dn;182 ++__first.__seg_;183 }184 // do middle whole words185 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {186 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);187 if (__b)188 return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));189 }190 // do last partial word191 if (__n > 0) {192 __storage_type __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);193 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;194 if (__b)195 return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));196 }197 return _It(__first.__seg_, static_cast<unsigned>(__n));198}199 200template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0>201inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst>202__find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) {203 if (static_cast<bool>(__value))204 return std::__find_bool<true>(205 __first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first));206 return std::__find_bool<false>(207 __first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first));208}209 210// segmented iterator implementation211 212template <class>213struct __find_segment;214 215template <class _SegmentedIterator,216 class _Tp,217 class _Proj,218 __enable_if_t<__is_segmented_iterator_v<_SegmentedIterator>, int> = 0>219_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator220__find(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) {221 return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj);222}223 224template <class _Tp>225struct __find_segment {226 const _Tp& __value_;227 228 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {}229 230 template <class _InputIterator, class _Proj>231 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator232 operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const {233 return std::__rewrap_iter(234 __first, std::__find(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value_, __proj));235 }236};237 238// public API239template <class _InputIterator, class _Tp>240[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator241find(_InputIterator __first, _InputIterator __last, const _Tp& __value) {242 __identity __proj;243 return std::__rewrap_iter(244 __first, std::__find(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj));245}246 247_LIBCPP_END_NAMESPACE_STD248 249_LIBCPP_POP_MACROS250 251#endif // _LIBCPP___ALGORITHM_FIND_H252