libcxx/include/__algorithm/mismatch.h

   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-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___ALGORITHM_MISMATCH_H
  11 #define _LIBCPP___ALGORITHM_MISMATCH_H
  12
  13 #include <__algorithm/comp.h>
  14 #include <__algorithm/min.h>
  15 #include <__algorithm/simd_utils.h>
  16 #include <__algorithm/unwrap_iter.h>
  17 #include <__config>
  18 #include <__cstddef/size_t.h>
  19 #include <__functional/identity.h>
  20 #include <__iterator/aliasing_iterator.h>
  21 #include <__iterator/iterator_traits.h>
  22 #include <__type_traits/desugars_to.h>
  23 #include <__type_traits/enable_if.h>
  24 #include <__type_traits/invoke.h>
  25 #include <__type_traits/is_constant_evaluated.h>
  26 #include <__type_traits/is_equality_comparable.h>
  27 #include <__type_traits/is_integral.h>
  28 #include <__utility/move.h>
  29 #include <__utility/pair.h>
  30 #include <__utility/unreachable.h>
  31
  32 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  33 #  pragma GCC system_header
  34 #endif
  35
  36 _LIBCPP_PUSH_MACROS
  37 #include <__undef_macros>
  38
  39 _LIBCPP_BEGIN_NAMESPACE_STD
  40
  41 template <class _Iter1, class _Sent1, class _Iter2, class _Pred, class _Proj1, class _Proj2>
  42 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter1, _Iter2>
  43 __mismatch_loop(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Pred& __pred, _Proj1& __proj1, _Proj2& __proj2) {
  44   while (__first1 != __last1) {
  45     if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
  46       break;
  47     ++__first1;
  48     ++__first2;
  49   }
  50   return std::make_pair(std::move(__first1), std::move(__first2));
  51 }
  52
  53 template <class _Iter1, class _Sent1, class _Iter2, class _Pred, class _Proj1, class _Proj2>
  54 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter1, _Iter2>
  55 __mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Pred& __pred, _Proj1& __proj1, _Proj2& __proj2) {
  56   return std::__mismatch_loop(__first1, __last1, __first2, __pred, __proj1, __proj2);
  57 }
  58
  59 #if _LIBCPP_VECTORIZE_ALGORITHMS
  60
  61 template <class _Iter>
  62 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter, _Iter>
  63 __mismatch_vectorized(_Iter __first1, _Iter __last1, _Iter __first2) {
  64   using __value_type              = __iter_value_type<_Iter>;
  65   constexpr size_t __unroll_count = 4;
  66   constexpr size_t __vec_size     = __native_vector_size<__value_type>;
  67   using __vec                     = __simd_vector<__value_type, __vec_size>;
  68
  69   if (!__libcpp_is_constant_evaluated()) {
  70     auto __orig_first1 = __first1;
  71     auto __last2       = __first2 + (__last1 - __first1);
  72     while (static_cast<size_t>(__last1 - __first1) >= __unroll_count * __vec_size) [[__unlikely__]] {
  73       __vec __lhs[__unroll_count];
  74       __vec __rhs[__unroll_count];
  75
  76       for (size_t __i = 0; __i != __unroll_count; ++__i) {
  77         __lhs[__i] = std::__load_vector<__vec>(__first1 + __i * __vec_size);
  78         __rhs[__i] = std::__load_vector<__vec>(__first2 + __i * __vec_size);
  79       }
  80
  81       for (size_t __i = 0; __i != __unroll_count; ++__i) {
  82         if (auto __cmp_res = __lhs[__i] == __rhs[__i]; !std::__all_of(__cmp_res)) {
  83           auto __offset = __i * __vec_size + std::__find_first_not_set(__cmp_res);
  84           return {__first1 + __offset, __first2 + __offset};
  85         }
  86       }
  87
  88       __first1 += __unroll_count * __vec_size;
  89       __first2 += __unroll_count * __vec_size;
  90     }
  91
  92     // check the remaining 0-3 vectors
  93     while (static_cast<size_t>(__last1 - __first1) >= __vec_size) {
  94       if (auto __cmp_res = std::__load_vector<__vec>(__first1) == std::__load_vector<__vec>(__first2);
  95           !std::__all_of(__cmp_res)) {
  96         auto __offset = std::__find_first_not_set(__cmp_res);
  97         return {__first1 + __offset, __first2 + __offset};
  98       }
  99       __first1 += __vec_size;
 100       __first2 += __vec_size;
 101     }
 102
 103     if (__last1 - __first1 == 0)
 104       return {__first1, __first2};
 105
 106     // Check if we can load elements in front of the current pointer. If that's the case load a vector at
 107     // (last - vector_size) to check the remaining elements
 108     if (static_cast<size_t>(__first1 - __orig_first1) >= __vec_size) {
 109       __first1 = __last1 - __vec_size;
 110       __first2 = __last2 - __vec_size;
 111       auto __offset =
 112           std::__find_first_not_set(std::__load_vector<__vec>(__first1) == std::__load_vector<__vec>(__first2));
 113       return {__first1 + __offset, __first2 + __offset};
 114     } // else loop over the elements individually
 115   }
 116
 117   __equal_to __pred;
 118   __identity __proj;
 119   return std::__mismatch_loop(__first1, __last1, __first2, __pred, __proj, __proj);
 120 }
 121
 122 template <class _Tp,
 123           class _Pred,
 124           class _Proj1,
 125           class _Proj2,
 126           __enable_if_t<is_integral<_Tp>::value && __desugars_to_v<__equal_tag, _Pred, _Tp, _Tp> &&
 127                             __is_identity<_Proj1>::value && __is_identity<_Proj2>::value,
 128                         int> = 0>
 129 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Tp*, _Tp*>
 130 __mismatch(_Tp* __first1, _Tp* __last1, _Tp* __first2, _Pred&, _Proj1&, _Proj2&) {
 131   return std::__mismatch_vectorized(__first1, __last1, __first2);
 132 }
 133
 134 template <class _Tp,
 135           class _Pred,
 136           class _Proj1,
 137           class _Proj2,
 138           __enable_if_t<!is_integral<_Tp>::value && __desugars_to_v<__equal_tag, _Pred, _Tp, _Tp> &&
 139                             __is_identity<_Proj1>::value && __is_identity<_Proj2>::value &&
 140                             __can_map_to_integer_v<_Tp> && __libcpp_is_trivially_equality_comparable<_Tp, _Tp>::value,
 141                         int> = 0>
 142 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Tp*, _Tp*>
 143 __mismatch(_Tp* __first1, _Tp* __last1, _Tp* __first2, _Pred& __pred, _Proj1& __proj1, _Proj2& __proj2) {
 144   if (__libcpp_is_constant_evaluated()) {
 145     return std::__mismatch_loop(__first1, __last1, __first2, __pred, __proj1, __proj2);
 146   } else {
 147     using _Iter = __aliasing_iterator<_Tp*, __get_as_integer_type_t<_Tp>>;
 148     auto __ret  = std::__mismatch_vectorized(_Iter(__first1), _Iter(__last1), _Iter(__first2));
 149     return {__ret.first.__base(), __ret.second.__base()};
 150   }
 151 }
 152 #endif // _LIBCPP_VECTORIZE_ALGORITHMS
 153
 154 template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
 155 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator1, _InputIterator2>
 156 mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred) {
 157   __identity __proj;
 158   auto __res = std::__mismatch(
 159       std::__unwrap_iter(__first1), std::__unwrap_iter(__last1), std::__unwrap_iter(__first2), __pred, __proj, __proj);
 160   return std::make_pair(std::__rewrap_iter(__first1, __res.first), std::__rewrap_iter(__first2, __res.second));
 161 }
 162
 163 template <class _InputIterator1, class _InputIterator2>
 164 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator1, _InputIterator2>
 165 mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2) {
 166   return std::mismatch(__first1, __last1, __first2, __equal_to());
 167 }
 168
 169 #if _LIBCPP_STD_VER >= 14
 170 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Pred, class _Proj1, class _Proj2>
 171 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter1, _Iter2> __mismatch(
 172     _Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2, _Pred& __pred, _Proj1& __proj1, _Proj2& __proj2) {
 173   while (__first1 != __last1 && __first2 != __last2) {
 174     if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
 175       break;
 176     ++__first1;
 177     ++__first2;
 178   }
 179   return {std::move(__first1), std::move(__first2)};
 180 }
 181
 182 template <class _Tp, class _Pred, class _Proj1, class _Proj2>
 183 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Tp*, _Tp*>
 184 __mismatch(_Tp* __first1, _Tp* __last1, _Tp* __first2, _Tp* __last2, _Pred& __pred, _Proj1& __proj1, _Proj2& __proj2) {
 185   auto __len = std::min(__last1 - __first1, __last2 - __first2);
 186   return std::__mismatch(__first1, __first1 + __len, __first2, __pred, __proj1, __proj2);
 187 }
 188
 189 template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
 190 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator1, _InputIterator2>
 191 mismatch(_InputIterator1 __first1,
 192          _InputIterator1 __last1,
 193          _InputIterator2 __first2,
 194          _InputIterator2 __last2,
 195          _BinaryPredicate __pred) {
 196   __identity __proj;
 197   auto __res = std::__mismatch(
 198       std::__unwrap_iter(__first1),
 199       std::__unwrap_iter(__last1),
 200       std::__unwrap_iter(__first2),
 201       std::__unwrap_iter(__last2),
 202       __pred,
 203       __proj,
 204       __proj);
 205   return {std::__rewrap_iter(__first1, __res.first), std::__rewrap_iter(__first2, __res.second)};
 206 }
 207
 208 template <class _InputIterator1, class _InputIterator2>
 209 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator1, _InputIterator2>
 210 mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2) {
 211   return std::mismatch(__first1, __last1, __first2, __last2, __equal_to());
 212 }
 213 #endif
 214
 215 _LIBCPP_END_NAMESPACE_STD
 216
 217 _LIBCPP_POP_MACROS
 218
 219 #endif // _LIBCPP___ALGORITHM_MISMATCH_H