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diff --git a/contrib/llvm-project/libcxx/include/__pstl/internal/algorithm_impl.h b/contrib/llvm-project/libcxx/include/__pstl/internal/algorithm_impl.h
new file mode 100644
index 000000000000..72043ebbf762
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+++ b/contrib/llvm-project/libcxx/include/__pstl/internal/algorithm_impl.h
@@ -0,0 +1,4174 @@
+// -*- 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 _PSTL_ALGORITHM_IMPL_H
+#define _PSTL_ALGORITHM_IMPL_H
+
+#include <__assert>
+#include <__config>
+#include <algorithm>
+#include <functional>
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+#include "execution_impl.h"
+#include "memory_impl.h"
+#include "parallel_backend.h"
+#include "parallel_backend_utils.h"
+#include "parallel_impl.h"
+#include "unseq_backend_simd.h"
+
+namespace __pstl {
+namespace __internal {
+
+// [alg.foreach]
+// for_each_n with no policy
+
+template <class _ForwardIterator, class _Size, class _Function>
+_ForwardIterator __for_each_n_it_serial(_ForwardIterator __first, _Size __n, _Function __f) {
+  for (; __n > 0; ++__first, --__n)
+    __f(__first);
+  return __first;
+}
+
+//------------------------------------------------------------------------
+// walk1 (pseudo)
+//
+// walk1 evaluates f(x) for each dereferenced value x drawn from [first,last)
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _Function>
+void __brick_walk1(
+    _ForwardIterator __first, _ForwardIterator __last, _Function __f, /*vector=*/std::false_type) noexcept {
+  std::for_each(__first, __last, __f);
+}
+
+template <class _RandomAccessIterator, class _Function>
+void __brick_walk1(_RandomAccessIterator __first,
+                   _RandomAccessIterator __last,
+                   _Function __f,
+                   /*vector=*/std::true_type) noexcept {
+  __unseq_backend::__simd_walk_1(__first, __last - __first, __f);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Function>
+void __pattern_walk1(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Function __f) noexcept {
+  __internal::__brick_walk1(__first, __last, __f, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Function>
+void __pattern_walk1(__parallel_tag<_IsVector> __tag,
+                     _ExecutionPolicy&& __exec,
+                     _RandomAccessIterator __first,
+                     _RandomAccessIterator __last,
+                     _Function __f) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        [__f](_RandomAccessIterator __i, _RandomAccessIterator __j) {
+          __internal::__brick_walk1(__i, __j, __f, _IsVector{});
+        });
+  });
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Brick>
+void __pattern_walk_brick(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Brick __brick) noexcept {
+  __brick(__first, __last);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Brick>
+void __pattern_walk_brick(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Brick __brick) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        [__brick](_RandomAccessIterator __i, _RandomAccessIterator __j) { __brick(__i, __j); });
+  });
+}
+
+//------------------------------------------------------------------------
+// walk1_n
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _Size, class _Function>
+_ForwardIterator __brick_walk1_n(_ForwardIterator __first, _Size __n, _Function __f, /*_IsVectorTag=*/std::false_type) {
+  return __internal::__for_each_n_it_serial(__first, __n, [&__f](_ForwardIterator __it) {
+    __f(*__it);
+  }); // calling serial version
+}
+
+template <class _RandomAccessIterator, class _DifferenceType, class _Function>
+_RandomAccessIterator
+__brick_walk1_n(_RandomAccessIterator __first,
+                _DifferenceType __n,
+                _Function __f,
+                /*vectorTag=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_walk_1(__first, __n, __f);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Function>
+_ForwardIterator
+__pattern_walk1_n(_Tag, _ExecutionPolicy&&, _ForwardIterator __first, _Size __n, _Function __f) noexcept {
+  return __internal::__brick_walk1_n(__first, __n, __f, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Function>
+_RandomAccessIterator __pattern_walk1_n(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _Size __n,
+    _Function __f) {
+  __internal::__pattern_walk1(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __first + __n, __f);
+
+  return __first + __n;
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Brick>
+_ForwardIterator
+__pattern_walk_brick_n(_Tag, _ExecutionPolicy&&, _ForwardIterator __first, _Size __n, _Brick __brick) noexcept {
+  return __brick(__first, __n);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Brick>
+_RandomAccessIterator __pattern_walk_brick_n(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _Size __n,
+    _Brick __brick) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __first + __n,
+        [__brick](_RandomAccessIterator __i, _RandomAccessIterator __j) { __brick(__i, __j - __i); });
+    return __first + __n;
+  });
+}
+
+//------------------------------------------------------------------------
+// walk2 (pseudo)
+//
+// walk2 evaluates f(x,y) for deferenced values (x,y) drawn from [first1,last1) and [first2,...)
+//------------------------------------------------------------------------
+template <class _ForwardIterator1, class _ForwardIterator2, class _Function>
+_ForwardIterator2
+__brick_walk2(_ForwardIterator1 __first1,
+              _ForwardIterator1 __last1,
+              _ForwardIterator2 __first2,
+              _Function __f,
+              /*vector=*/std::false_type) noexcept {
+  for (; __first1 != __last1; ++__first1, ++__first2)
+    __f(*__first1, *__first2);
+  return __first2;
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Function>
+_RandomAccessIterator2
+__brick_walk2(_RandomAccessIterator1 __first1,
+              _RandomAccessIterator1 __last1,
+              _RandomAccessIterator2 __first2,
+              _Function __f,
+              /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_walk_2(__first1, __last1 - __first1, __first2, __f);
+}
+
+template <class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Function>
+_ForwardIterator2 __brick_walk2_n(
+    _ForwardIterator1 __first1,
+    _Size __n,
+    _ForwardIterator2 __first2,
+    _Function __f,
+    /*vector=*/std::false_type) noexcept {
+  for (; __n > 0; --__n, ++__first1, ++__first2)
+    __f(*__first1, *__first2);
+  return __first2;
+}
+
+template <class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2, class _Function>
+_RandomAccessIterator2 __brick_walk2_n(
+    _RandomAccessIterator1 __first1,
+    _Size __n,
+    _RandomAccessIterator2 __first2,
+    _Function __f,
+    /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_walk_2(__first1, __n, __first2, __f);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function>
+_ForwardIterator2 __pattern_walk2(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _Function __f) noexcept {
+  return __internal::__brick_walk2(__first1, __last1, __first2, __f, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _Function>
+_RandomAccessIterator2 __pattern_walk2(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _Function __f) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        [__f, __first1, __first2](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          __internal::__brick_walk2(__i, __j, __first2 + (__i - __first1), __f, _IsVector{});
+        });
+    return __first2 + (__last1 - __first1);
+  });
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _Size,
+          class _ForwardIterator2,
+          class _Function>
+_ForwardIterator2 __pattern_walk2_n(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _Size __n,
+    _ForwardIterator2 __first2,
+    _Function __f) noexcept {
+  return __internal::__brick_walk2_n(__first1, __n, __first2, __f, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _Size,
+          class _RandomAccessIterator2,
+          class _Function>
+_RandomAccessIterator2 __pattern_walk2_n(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _Size __n,
+    _RandomAccessIterator2 __first2,
+    _Function __f) {
+  return __internal::__pattern_walk2(
+      __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __first1 + __n, __first2, __f);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Brick>
+_ForwardIterator2 __pattern_walk2_brick(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _Brick __brick) noexcept {
+  return __brick(__first1, __last1, __first2);
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _Brick>
+_RandomAccessIterator2 __pattern_walk2_brick(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _Brick __brick) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        [__first1, __first2, __brick](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          __brick(__i, __j, __first2 + (__i - __first1));
+        });
+    return __first2 + (__last1 - __first1);
+  });
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _Size,
+          class _ForwardIterator2,
+          class _Brick>
+_ForwardIterator2 __pattern_walk2_brick_n(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _Size __n,
+    _ForwardIterator2 __first2,
+    _Brick __brick) noexcept {
+  return __brick(__first1, __n, __first2);
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _Size,
+          class _RandomAccessIterator2,
+          class _Brick>
+_RandomAccessIterator2 __pattern_walk2_brick_n(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _Size __n,
+    _RandomAccessIterator2 __first2,
+    _Brick __brick) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __first1 + __n,
+        [__first1, __first2, __brick](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          __brick(__i, __j - __i, __first2 + (__i - __first1));
+        });
+    return __first2 + __n;
+  });
+}
+
+//------------------------------------------------------------------------
+// walk3 (pseudo)
+//
+// walk3 evaluates f(x,y,z) for (x,y,z) drawn from [first1,last1), [first2,...), [first3,...)
+//------------------------------------------------------------------------
+template <class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator3, class _Function>
+_ForwardIterator3 __brick_walk3(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator3 __first3,
+    _Function __f,
+    /*vector=*/std::false_type) noexcept {
+  for (; __first1 != __last1; ++__first1, ++__first2, ++__first3)
+    __f(*__first1, *__first2, *__first3);
+  return __first3;
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Function>
+_RandomAccessIterator3 __brick_walk3(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator3 __first3,
+    _Function __f,
+    /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_walk_3(__first1, __last1 - __first1, __first2, __first3, __f);
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _ForwardIterator3,
+          class _Function>
+_ForwardIterator3 __pattern_walk3(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator3 __first3,
+    _Function __f) noexcept {
+  return __internal::__brick_walk3(__first1, __last1, __first2, __first3, __f, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _Function>
+_RandomAccessIterator3 __pattern_walk3(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator3 __first3,
+    _Function __f) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        [__f, __first1, __first2, __first3](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          __internal::__brick_walk3(
+              __i, __j, __first2 + (__i - __first1), __first3 + (__i - __first1), __f, _IsVector{});
+        });
+    return __first3 + (__last1 - __first1);
+  });
+}
+
+//------------------------------------------------------------------------
+// equal
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+bool __brick_equal(_ForwardIterator1 __first1,
+                   _ForwardIterator1 __last1,
+                   _ForwardIterator2 __first2,
+                   _ForwardIterator2 __last2,
+                   _BinaryPredicate __p,
+                   /* IsVector = */ std::false_type) noexcept {
+  return std::equal(__first1, __last1, __first2, __last2, __p);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+bool __brick_equal(_RandomAccessIterator1 __first1,
+                   _RandomAccessIterator1 __last1,
+                   _RandomAccessIterator2 __first2,
+                   _RandomAccessIterator2 __last2,
+                   _BinaryPredicate __p,
+                   /* is_vector = */ std::true_type) noexcept {
+  if (__last1 - __first1 != __last2 - __first2)
+    return false;
+
+  return __unseq_backend::__simd_first(__first1, __last1 - __first1, __first2, std::not_fn(__p)).first == __last1;
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+bool __pattern_equal(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _BinaryPredicate __p) noexcept {
+  return __internal::__brick_equal(__first1, __last1, __first2, __last2, __p, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _BinaryPredicate>
+bool __pattern_equal(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _BinaryPredicate __p) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__last1 - __first1 != __last2 - __first2)
+    return false;
+
+  return __internal::__except_handler([&]() {
+    return !__internal::__parallel_or(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        [__first1, __first2, __p](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          return !__internal::__brick_equal(
+              __i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1), __p, _IsVector{});
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// equal version for sequences with equal length
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+bool __brick_equal(_ForwardIterator1 __first1,
+                   _ForwardIterator1 __last1,
+                   _ForwardIterator2 __first2,
+                   _BinaryPredicate __p,
+                   /* IsVector = */ std::false_type) noexcept {
+  return std::equal(__first1, __last1, __first2, __p);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+bool __brick_equal(_RandomAccessIterator1 __first1,
+                   _RandomAccessIterator1 __last1,
+                   _RandomAccessIterator2 __first2,
+                   _BinaryPredicate __p,
+                   /* is_vector = */ std::true_type) noexcept {
+  return __unseq_backend::__simd_first(__first1, __last1 - __first1, __first2, std::not_fn(__p)).first == __last1;
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+bool __pattern_equal(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _BinaryPredicate __p) noexcept {
+  return __internal::__brick_equal(__first1, __last1, __first2, __p, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _BinaryPredicate>
+bool __pattern_equal(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _BinaryPredicate __p) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    return !__internal::__parallel_or(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        [__first1, __first2, __p](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          return !__internal::__brick_equal(__i, __j, __first2 + (__i - __first1), __p, _IsVector{});
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// find_end
+//------------------------------------------------------------------------
+
+// find the first occurrence of the subsequence [s_first, s_last)
+//   or the  last occurrence of the subsequence in the range [first, last)
+// b_first determines what occurrence we want to find (first or last)
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate, class _IsVector>
+_RandomAccessIterator1 __find_subrange(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator1 __global_last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred,
+    bool __b_first,
+    _IsVector __is_vector) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator2>::value_type _ValueType;
+  auto __n2 = __s_last - __s_first;
+  if (__n2 < 1) {
+    return __b_first ? __first : __last;
+  }
+
+  auto __n1 = __global_last - __first;
+  if (__n1 < __n2) {
+    return __last;
+  }
+
+  auto __cur = __last;
+  while (__first != __last && (__global_last - __first >= __n2)) {
+    // find position of *s_first in [first, last) (it can be start of subsequence)
+    __first = __internal::__brick_find_if(
+        __first, __last, __equal_value_by_pred<_ValueType, _BinaryPredicate>(*__s_first, __pred), __is_vector);
+
+    // if position that was found previously is the start of subsequence
+    // then we can exit the loop (b_first == true) or keep the position
+    // (b_first == false)
+    if (__first != __last && (__global_last - __first >= __n2) &&
+        __internal::__brick_equal(__s_first + 1, __s_last, __first + 1, __pred, __is_vector)) {
+      if (__b_first) {
+        return __first;
+      } else {
+        __cur = __first;
+      }
+    } else if (__first == __last) {
+      break;
+    } else {
+    }
+
+    // in case of b_first == false we try to find new start position
+    // for the next subsequence
+    ++__first;
+  }
+  return __cur;
+}
+
+template <class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate, class _IsVector>
+_RandomAccessIterator __find_subrange(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _RandomAccessIterator __global_last,
+    _Size __count,
+    const _Tp& __value,
+    _BinaryPredicate __pred,
+    _IsVector __is_vector) noexcept {
+  if (static_cast<_Size>(__global_last - __first) < __count || __count < 1) {
+    return __last; // According to the standard last shall be returned when count < 1
+  }
+
+  auto __unary_pred = __equal_value_by_pred<_Tp, _BinaryPredicate>(__value, __pred);
+  while (__first != __last && (static_cast<_Size>(__global_last - __first) >= __count)) {
+    __first = __internal::__brick_find_if(__first, __last, __unary_pred, __is_vector);
+
+    // check that all of elements in [first+1, first+count) equal to value
+    if (__first != __last && (static_cast<_Size>(__global_last - __first) >= __count) &&
+        !__internal::__brick_any_of(__first + 1, __first + __count, std::not_fn(__unary_pred), __is_vector)) {
+      return __first;
+    } else if (__first == __last) {
+      break;
+    } else {
+      ++__first;
+    }
+  }
+  return __last;
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_ForwardIterator1 __brick_find_end(
+    _ForwardIterator1 __first,
+    _ForwardIterator1 __last,
+    _ForwardIterator2 __s_first,
+    _ForwardIterator2 __s_last,
+    _BinaryPredicate __pred,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::find_end(__first, __last, __s_first, __s_last, __pred);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+_RandomAccessIterator1 __brick_find_end(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred,
+    /*__is_vector=*/std::true_type) noexcept {
+  return __find_subrange(__first, __last, __last, __s_first, __s_last, __pred, false, std::true_type());
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_ForwardIterator1 __pattern_find_end(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first,
+    _ForwardIterator1 __last,
+    _ForwardIterator2 __s_first,
+    _ForwardIterator2 __s_last,
+    _BinaryPredicate __pred) noexcept {
+  return __internal::__brick_find_end(__first, __last, __s_first, __s_last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _BinaryPredicate>
+_RandomAccessIterator1 __pattern_find_end(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__last - __first == __s_last - __s_first) {
+    const bool __res =
+        __internal::__pattern_equal(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __pred);
+    return __res ? __first : __last;
+  } else {
+    return __internal::__except_handler([&]() {
+      return __internal::__parallel_find(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __first,
+          __last,
+          [__last, __s_first, __s_last, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+            return __internal::__find_subrange(__i, __j, __last, __s_first, __s_last, __pred, false, _IsVector{});
+          },
+          std::greater<typename std::iterator_traits<_RandomAccessIterator1>::difference_type>(),
+          /*is_first=*/false);
+    });
+  }
+}
+
+//------------------------------------------------------------------------
+// find_first_of
+//------------------------------------------------------------------------
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_ForwardIterator1 __brick_find_first_of(
+    _ForwardIterator1 __first,
+    _ForwardIterator1 __last,
+    _ForwardIterator2 __s_first,
+    _ForwardIterator2 __s_last,
+    _BinaryPredicate __pred,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::find_first_of(__first, __last, __s_first, __s_last, __pred);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+_RandomAccessIterator1 __brick_find_first_of(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred,
+    /*__is_vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_find_first_of(__first, __last, __s_first, __s_last, __pred);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_ForwardIterator1 __pattern_find_first_of(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first,
+    _ForwardIterator1 __last,
+    _ForwardIterator2 __s_first,
+    _ForwardIterator2 __s_last,
+    _BinaryPredicate __pred) noexcept {
+  return __internal::__brick_find_first_of(__first, __last, __s_first, __s_last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _BinaryPredicate>
+_RandomAccessIterator1 __pattern_find_first_of(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    return __internal::__parallel_find(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        [__s_first, __s_last, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          return __internal::__brick_find_first_of(__i, __j, __s_first, __s_last, __pred, _IsVector{});
+        },
+        std::less<typename std::iterator_traits<_RandomAccessIterator1>::difference_type>(),
+        /*is_first=*/true);
+  });
+}
+
+//------------------------------------------------------------------------
+// search
+//------------------------------------------------------------------------
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+_RandomAccessIterator1 __brick_search(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred,
+    /*vector=*/std::false_type) noexcept {
+  return std::search(__first, __last, __s_first, __s_last, __pred);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+_RandomAccessIterator1 __brick_search(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred,
+    /*vector=*/std::true_type) noexcept {
+  return __internal::__find_subrange(__first, __last, __last, __s_first, __s_last, __pred, true, std::true_type());
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_ForwardIterator1 __pattern_search(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first,
+    _ForwardIterator1 __last,
+    _ForwardIterator2 __s_first,
+    _ForwardIterator2 __s_last,
+    _BinaryPredicate __pred) noexcept {
+  return __internal::__brick_search(__first, __last, __s_first, __s_last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _BinaryPredicate>
+_RandomAccessIterator1 __pattern_search(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __s_first,
+    _RandomAccessIterator2 __s_last,
+    _BinaryPredicate __pred) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__last - __first == __s_last - __s_first) {
+    const bool __res =
+        __internal::__pattern_equal(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __pred);
+    return __res ? __first : __last;
+  } else {
+    return __internal::__except_handler([&]() {
+      return __internal::__parallel_find(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __first,
+          __last,
+          [__last, __s_first, __s_last, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+            return __internal::__find_subrange(__i, __j, __last, __s_first, __s_last, __pred, true, _IsVector{});
+          },
+          std::less<typename std::iterator_traits<_RandomAccessIterator1>::difference_type>(),
+          /*is_first=*/true);
+    });
+  }
+}
+
+//------------------------------------------------------------------------
+// search_n
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
+_ForwardIterator __brick_search_n(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _Size __count,
+    const _Tp& __value,
+    _BinaryPredicate __pred,
+    /*vector=*/std::false_type) noexcept {
+  return std::search_n(__first, __last, __count, __value, __pred);
+}
+
+template <class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate>
+_RandomAccessIterator __brick_search_n(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Size __count,
+    const _Tp& __value,
+    _BinaryPredicate __pred,
+    /*vector=*/std::true_type) noexcept {
+  return __internal::__find_subrange(__first, __last, __last, __count, __value, __pred, std::true_type());
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
+_ForwardIterator __pattern_search_n(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _Size __count,
+    const _Tp& __value,
+    _BinaryPredicate __pred) noexcept {
+  return __internal::__brick_search_n(__first, __last, __count, __value, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator,
+          class _Size,
+          class _Tp,
+          class _BinaryPredicate>
+_RandomAccessIterator __pattern_search_n(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Size __count,
+    const _Tp& __value,
+    _BinaryPredicate __pred) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (static_cast<_Size>(__last - __first) == __count) {
+    const bool __result = !__internal::__pattern_any_of(
+        __tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [&__value, &__pred](const _Tp& __val) {
+          return !__pred(__val, __value);
+        });
+    return __result ? __first : __last;
+  } else {
+    return __internal::__except_handler([&__exec, __first, __last, __count, &__value, __pred]() {
+      return __internal::__parallel_find(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __first,
+          __last,
+          [__last, __count, &__value, __pred](_RandomAccessIterator __i, _RandomAccessIterator __j) {
+            return __internal::__find_subrange(__i, __j, __last, __count, __value, __pred, _IsVector{});
+          },
+          std::less<typename std::iterator_traits<_RandomAccessIterator>::difference_type>(),
+          /*is_first=*/true);
+    });
+  }
+}
+
+//------------------------------------------------------------------------
+// copy_n
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class _Size, class _OutputIterator>
+_OutputIterator
+__brick_copy_n(_ForwardIterator __first, _Size __n, _OutputIterator __result, /*vector=*/std::false_type) noexcept {
+  return std::copy_n(__first, __n, __result);
+}
+
+template <class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2>
+_RandomAccessIterator2
+__brick_copy_n(_RandomAccessIterator1 __first,
+               _Size __n,
+               _RandomAccessIterator2 __result,
+               /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_assign(
+      __first, __n, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
+        *__result = *__first;
+      });
+}
+
+//------------------------------------------------------------------------
+// copy
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _OutputIterator>
+_OutputIterator
+__brick_copy(_ForwardIterator __first,
+             _ForwardIterator __last,
+             _OutputIterator __result,
+             /*vector=*/std::false_type) noexcept {
+  return std::copy(__first, __last, __result);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2
+__brick_copy(_RandomAccessIterator1 __first,
+             _RandomAccessIterator1 __last,
+             _RandomAccessIterator2 __result,
+             /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_assign(
+      __first, __last - __first, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
+        *__result = *__first;
+      });
+}
+
+//------------------------------------------------------------------------
+// move
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _OutputIterator>
+_OutputIterator
+__brick_move(_ForwardIterator __first,
+             _ForwardIterator __last,
+             _OutputIterator __result,
+             /*vector=*/std::false_type) noexcept {
+  return std::move(__first, __last, __result);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2
+__brick_move(_RandomAccessIterator1 __first,
+             _RandomAccessIterator1 __last,
+             _RandomAccessIterator2 __result,
+             /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_assign(
+      __first, __last - __first, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
+        *__result = std::move(*__first);
+      });
+}
+
+struct __brick_move_destroy {
+  template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
+  _RandomAccessIterator2
+  operator()(_RandomAccessIterator1 __first,
+             _RandomAccessIterator1 __last,
+             _RandomAccessIterator2 __result,
+             /*vec*/ std::true_type) const {
+    using _IteratorValueType = typename std::iterator_traits<_RandomAccessIterator1>::value_type;
+
+    return __unseq_backend::__simd_assign(
+        __first, __last - __first, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
+          *__result = std::move(*__first);
+          (*__first).~_IteratorValueType();
+        });
+  }
+
+  template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
+  _RandomAccessIterator2
+  operator()(_RandomAccessIterator1 __first,
+             _RandomAccessIterator1 __last,
+             _RandomAccessIterator2 __result,
+             /*vec*/ std::false_type) const {
+    using _IteratorValueType = typename std::iterator_traits<_RandomAccessIterator1>::value_type;
+
+    for (; __first != __last; ++__first, ++__result) {
+      *__result = std::move(*__first);
+      (*__first).~_IteratorValueType();
+    }
+    return __result;
+  }
+};
+
+//------------------------------------------------------------------------
+// swap_ranges
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _OutputIterator>
+_OutputIterator __brick_swap_ranges(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator __result,
+    /*vector=*/std::false_type) noexcept {
+  return std::swap_ranges(__first, __last, __result);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2 __brick_swap_ranges(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    /*vector=*/std::true_type) noexcept {
+  using std::iter_swap;
+  return __unseq_backend::__simd_assign(
+      __first, __last - __first, __result, iter_swap<_RandomAccessIterator1, _RandomAccessIterator2>);
+}
+
+//------------------------------------------------------------------------
+// copy_if
+//------------------------------------------------------------------------
+template <class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
+_OutputIterator __brick_copy_if(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator __result,
+    _UnaryPredicate __pred,
+    /*vector=*/std::false_type) noexcept {
+  return std::copy_if(__first, __last, __result, __pred);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _UnaryPredicate>
+_RandomAccessIterator2 __brick_copy_if(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    _UnaryPredicate __pred,
+    /*vector=*/std::true_type) noexcept {
+#if defined(_PSTL_MONOTONIC_PRESENT)
+  return __unseq_backend::__simd_copy_if(__first, __last - __first, __result, __pred);
+#else
+  return std::copy_if(__first, __last, __result, __pred);
+#endif
+}
+
+// TODO: Try to use transform_reduce for combining __brick_copy_if_phase1 on IsVector.
+template <class _DifferenceType, class _ForwardIterator, class _UnaryPredicate>
+std::pair<_DifferenceType, _DifferenceType> __brick_calc_mask_1(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    bool* __restrict __mask,
+    _UnaryPredicate __pred,
+    /*vector=*/std::false_type) noexcept {
+  auto __count_true = _DifferenceType(0);
+  auto __size       = __last - __first;
+
+  static_assert(__are_random_access_iterators<_ForwardIterator>::value,
+                "Pattern-brick error. Should be a random access iterator.");
+
+  for (; __first != __last; ++__first, ++__mask) {
+    *__mask = __pred(*__first);
+    if (*__mask) {
+      ++__count_true;
+    }
+  }
+  return std::make_pair(__count_true, __size - __count_true);
+}
+
+template <class _DifferenceType, class _RandomAccessIterator, class _UnaryPredicate>
+std::pair<_DifferenceType, _DifferenceType> __brick_calc_mask_1(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    bool* __mask,
+    _UnaryPredicate __pred,
+    /*vector=*/std::true_type) noexcept {
+  auto __result = __unseq_backend::__simd_calc_mask_1(__first, __last - __first, __mask, __pred);
+  return std::make_pair(__result, (__last - __first) - __result);
+}
+
+template <class _ForwardIterator, class _OutputIterator, class _Assigner>
+void __brick_copy_by_mask(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator __result,
+    bool* __mask,
+    _Assigner __assigner,
+    /*vector=*/std::false_type) noexcept {
+  for (; __first != __last; ++__first, ++__mask) {
+    if (*__mask) {
+      __assigner(__first, __result);
+      ++__result;
+    }
+  }
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Assigner>
+void __brick_copy_by_mask(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    bool* __restrict __mask,
+    _Assigner __assigner,
+    /*vector=*/std::true_type) noexcept {
+#if defined(_PSTL_MONOTONIC_PRESENT)
+  __unseq_backend::__simd_copy_by_mask(__first, __last - __first, __result, __mask, __assigner);
+#else
+  __internal::__brick_copy_by_mask(__first, __last, __result, __mask, __assigner, std::false_type());
+#endif
+}
+
+template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2>
+void __brick_partition_by_mask(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator1 __out_true,
+    _OutputIterator2 __out_false,
+    bool* __mask,
+    /*vector=*/std::false_type) noexcept {
+  for (; __first != __last; ++__first, ++__mask) {
+    if (*__mask) {
+      *__out_true = *__first;
+      ++__out_true;
+    } else {
+      *__out_false = *__first;
+      ++__out_false;
+    }
+  }
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3>
+void __brick_partition_by_mask(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __out_true,
+    _RandomAccessIterator3 __out_false,
+    bool* __mask,
+    /*vector=*/std::true_type) noexcept {
+#if defined(_PSTL_MONOTONIC_PRESENT)
+  __unseq_backend::__simd_partition_by_mask(__first, __last - __first, __out_true, __out_false, __mask);
+#else
+  __internal::__brick_partition_by_mask(__first, __last, __out_true, __out_false, __mask, std::false_type());
+#endif
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
+_OutputIterator __pattern_copy_if(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator __result,
+    _UnaryPredicate __pred) noexcept {
+  return __internal::__brick_copy_if(__first, __last, __result, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _UnaryPredicate>
+_RandomAccessIterator2 __pattern_copy_if(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    _UnaryPredicate __pred) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType;
+  const _DifferenceType __n = __last - __first;
+  if (_DifferenceType(1) < __n) {
+    __par_backend::__buffer<bool> __mask_buf(__n);
+    return __internal::__except_handler([&__exec, __n, __first, __result, __pred, &__mask_buf]() {
+      bool* __mask = __mask_buf.get();
+      _DifferenceType __m{};
+      __par_backend::__parallel_strict_scan(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __n,
+          _DifferenceType(0),
+          [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
+            return __internal::__brick_calc_mask_1<_DifferenceType>(
+                       __first + __i, __first + (__i + __len), __mask + __i, __pred, _IsVector{})
+                .first;
+          },
+          std::plus<_DifferenceType>(),                                                // Combine
+          [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) { // Scan
+            __internal::__brick_copy_by_mask(
+                __first + __i,
+                __first + (__i + __len),
+                __result + __initial,
+                __mask + __i,
+                [](_RandomAccessIterator1 __x, _RandomAccessIterator2 __z) { *__z = *__x; },
+                _IsVector{});
+          },
+          [&__m](_DifferenceType __total) { __m = __total; });
+      return __result + __m;
+    });
+  }
+  // trivial sequence - use serial algorithm
+  return __internal::__brick_copy_if(__first, __last, __result, __pred, _IsVector{});
+}
+
+//------------------------------------------------------------------------
+// count
+//------------------------------------------------------------------------
+template <class _RandomAccessIterator, class _Predicate>
+typename std::iterator_traits<_RandomAccessIterator>::difference_type
+__brick_count(_RandomAccessIterator __first,
+              _RandomAccessIterator __last,
+              _Predicate __pred,
+              /* is_vector = */ std::true_type) noexcept {
+  return __unseq_backend::__simd_count(__first, __last - __first, __pred);
+}
+
+template <class _ForwardIterator, class _Predicate>
+typename std::iterator_traits<_ForwardIterator>::difference_type
+__brick_count(_ForwardIterator __first,
+              _ForwardIterator __last,
+              _Predicate __pred,
+              /* is_vector = */ std::false_type) noexcept {
+  return std::count_if(__first, __last, __pred);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Predicate>
+typename std::iterator_traits<_ForwardIterator>::difference_type __pattern_count(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) noexcept {
+  return __internal::__brick_count(__first, __last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Predicate>
+typename std::iterator_traits<_RandomAccessIterator>::difference_type __pattern_count(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Predicate __pred) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type _SizeType;
+  return __internal::__except_handler([&]() {
+    return __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        _SizeType(0),
+        [__pred](_RandomAccessIterator __begin, _RandomAccessIterator __end, _SizeType __value) -> _SizeType {
+          return __value + __internal::__brick_count(__begin, __end, __pred, _IsVector{});
+        },
+        std::plus<_SizeType>());
+  });
+}
+
+//------------------------------------------------------------------------
+// unique
+//------------------------------------------------------------------------
+
+template <class _RandomAccessIterator, class _BinaryPredicate>
+_RandomAccessIterator
+__brick_unique(_RandomAccessIterator __first,
+               _RandomAccessIterator __last,
+               _BinaryPredicate __pred,
+               /*is_vector=*/std::false_type) noexcept {
+  return std::unique(__first, __last, __pred);
+}
+
+template <class _RandomAccessIterator, class _BinaryPredicate>
+_RandomAccessIterator
+__brick_unique(_RandomAccessIterator __first,
+               _RandomAccessIterator __last,
+               _BinaryPredicate __pred,
+               /*is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::unique(__first, __last, __pred);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
+_ForwardIterator __pattern_unique(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred) noexcept {
+  return __internal::__brick_unique(__first, __last, __pred, typename _Tag::__is_vector{});
+}
+
+// That function is shared between two algorithms - remove_if (__pattern_remove_if) and unique (pattern unique). But a
+// mask calculation is different. So, a caller passes _CalcMask brick into remove_elements.
+template <class _IsVector, class _ExecutionPolicy, class _ForwardIterator, class _CalcMask>
+_ForwardIterator __remove_elements(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _CalcMask __calc_mask) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_ForwardIterator>::difference_type _DifferenceType;
+  typedef typename std::iterator_traits<_ForwardIterator>::value_type _Tp;
+  _DifferenceType __n = __last - __first;
+  __par_backend::__buffer<bool> __mask_buf(__n);
+  // 1. find a first iterator that should be removed
+  return __internal::__except_handler([&]() {
+    bool* __mask          = __mask_buf.get();
+    _DifferenceType __min = __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        _DifferenceType(0),
+        __n,
+        __n,
+        [__first, __mask, &__calc_mask](
+            _DifferenceType __i, _DifferenceType __j, _DifferenceType __local_min) -> _DifferenceType {
+          // Create mask
+          __calc_mask(__mask + __i, __mask + __j, __first + __i);
+
+          // if minimum was found in a previous range we shouldn't do anymore
+          if (__local_min < __i) {
+            return __local_min;
+          }
+          // find first iterator that should be removed
+          bool* __result = __internal::__brick_find_if(
+              __mask + __i, __mask + __j, [](bool __val) { return !__val; }, _IsVector{});
+          if (__result - __mask == __j) {
+            return __local_min;
+          }
+          return std::min(__local_min, _DifferenceType(__result - __mask));
+        },
+        [](_DifferenceType __local_min1, _DifferenceType __local_min2) -> _DifferenceType {
+          return std::min(__local_min1, __local_min2);
+        });
+
+    // No elements to remove - exit
+    if (__min == __n) {
+      return __last;
+    }
+    __n -= __min;
+    __first += __min;
+
+    __par_backend::__buffer<_Tp> __buf(__n);
+    _Tp* __result = __buf.get();
+    __mask += __min;
+    _DifferenceType __m{};
+    // 2. Elements that doesn't satisfy pred are moved to result
+    __par_backend::__parallel_strict_scan(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __n,
+        _DifferenceType(0),
+        [__mask](_DifferenceType __i, _DifferenceType __len) {
+          return __internal::__brick_count(
+              __mask + __i, __mask + __i + __len, [](bool __val) { return __val; }, _IsVector{});
+        },
+        std::plus<_DifferenceType>(),
+        [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) {
+          __internal::__brick_copy_by_mask(
+              __first + __i,
+              __first + __i + __len,
+              __result + __initial,
+              __mask + __i,
+              [](_ForwardIterator __x, _Tp* __z) {
+                __internal::__invoke_if_else(
+                    std::is_trivial<_Tp>(),
+                    [&]() { *__z = std::move(*__x); },
+                    [&]() { ::new (std::addressof(*__z)) _Tp(std::move(*__x)); });
+              },
+              _IsVector{});
+        },
+        [&__m](_DifferenceType __total) { __m = __total; });
+
+    // 3. Elements from result are moved to [first, last)
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __result,
+        __result + __m,
+        [__result, __first](_Tp* __i, _Tp* __j) {
+          __invoke_if_else(
+              std::is_trivial<_Tp>(),
+              [&]() { __brick_move(__i, __j, __first + (__i - __result), _IsVector{}); },
+              [&]() { __brick_move_destroy()(__i, __j, __first + (__i - __result), _IsVector{}); });
+        });
+    return __first + __m;
+  });
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate>
+_RandomAccessIterator __pattern_unique(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _BinaryPredicate __pred) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
+
+  if (__first == __last) {
+    return __last;
+  }
+  if (__first + 1 == __last || __first + 2 == __last) {
+    // Trivial sequence - use serial algorithm
+    return __internal::__brick_unique(__first, __last, __pred, _IsVector{});
+  }
+  return __internal::__remove_elements(
+      __tag,
+      std::forward<_ExecutionPolicy>(__exec),
+      ++__first,
+      __last,
+      [&__pred](bool* __b, bool* __e, _RandomAccessIterator __it) {
+        __internal::__brick_walk3(
+            __b,
+            __e,
+            __it - 1,
+            __it,
+            [&__pred](bool& __x, _ReferenceType __y, _ReferenceType __z) { __x = !__pred(__y, __z); },
+            _IsVector{});
+      });
+}
+
+//------------------------------------------------------------------------
+// unique_copy
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class OutputIterator, class _BinaryPredicate>
+OutputIterator __brick_unique_copy(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    OutputIterator __result,
+    _BinaryPredicate __pred,
+    /*vector=*/std::false_type) noexcept {
+  return std::unique_copy(__first, __last, __result, __pred);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
+_RandomAccessIterator2 __brick_unique_copy(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    _BinaryPredicate __pred,
+    /*vector=*/std::true_type) noexcept {
+#if defined(_PSTL_MONOTONIC_PRESENT)
+  return __unseq_backend::__simd_unique_copy(__first, __last - __first, __result, __pred);
+#else
+  return std::unique_copy(__first, __last, __result, __pred);
+#endif
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _BinaryPredicate>
+_OutputIterator __pattern_unique_copy(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator __result,
+    _BinaryPredicate __pred) noexcept {
+  return __internal::__brick_unique_copy(__first, __last, __result, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
+_DifferenceType __brick_calc_mask_2(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    bool* __restrict __mask,
+    _BinaryPredicate __pred,
+    /*vector=*/std::false_type) noexcept {
+  _DifferenceType __count = 0;
+  for (; __first != __last; ++__first, ++__mask) {
+    *__mask = !__pred(*__first, *(__first - 1));
+    __count += *__mask;
+  }
+  return __count;
+}
+
+template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
+_DifferenceType __brick_calc_mask_2(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    bool* __restrict __mask,
+    _BinaryPredicate __pred,
+    /*vector=*/std::true_type) noexcept {
+  return __unseq_backend::__simd_calc_mask_2(__first, __last - __first, __mask, __pred);
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _BinaryPredicate>
+_RandomAccessIterator2 __pattern_unique_copy(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    _BinaryPredicate __pred) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType;
+  const _DifferenceType __n = __last - __first;
+  if (_DifferenceType(2) < __n) {
+    __par_backend::__buffer<bool> __mask_buf(__n);
+    if (_DifferenceType(2) < __n) {
+      return __internal::__except_handler([&__exec, __n, __first, __result, __pred, &__mask_buf]() {
+        bool* __mask = __mask_buf.get();
+        _DifferenceType __m{};
+        __par_backend::__parallel_strict_scan(
+            __backend_tag{},
+            std::forward<_ExecutionPolicy>(__exec),
+            __n,
+            _DifferenceType(0),
+            [=](_DifferenceType __i, _DifferenceType __len) -> _DifferenceType { // Reduce
+              _DifferenceType __extra = 0;
+              if (__i == 0) {
+                // Special boundary case
+                __mask[__i] = true;
+                if (--__len == 0)
+                  return 1;
+                ++__i;
+                ++__extra;
+              }
+              return __internal::__brick_calc_mask_2<_DifferenceType>(
+                         __first + __i, __first + (__i + __len), __mask + __i, __pred, _IsVector{}) +
+                     __extra;
+            },
+            std::plus<_DifferenceType>(),                                                // Combine
+            [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) { // Scan
+              // Phase 2 is same as for __pattern_copy_if
+              __internal::__brick_copy_by_mask(
+                  __first + __i,
+                  __first + (__i + __len),
+                  __result + __initial,
+                  __mask + __i,
+                  [](_RandomAccessIterator1 __x, _RandomAccessIterator2 __z) { *__z = *__x; },
+                  _IsVector{});
+            },
+            [&__m](_DifferenceType __total) { __m = __total; });
+        return __result + __m;
+      });
+    }
+  }
+  // trivial sequence - use serial algorithm
+  return __internal::__brick_unique_copy(__first, __last, __result, __pred, _IsVector{});
+}
+
+//------------------------------------------------------------------------
+// reverse
+//------------------------------------------------------------------------
+template <class _BidirectionalIterator>
+void __brick_reverse(
+    _BidirectionalIterator __first, _BidirectionalIterator __last, /*__is_vector=*/std::false_type) noexcept {
+  std::reverse(__first, __last);
+}
+
+template <class _RandomAccessIterator>
+void __brick_reverse(
+    _RandomAccessIterator __first, _RandomAccessIterator __last, /*__is_vector=*/std::true_type) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
+
+  const auto __n = (__last - __first) / 2;
+  __unseq_backend::__simd_walk_2(
+      __first, __n, std::reverse_iterator<_RandomAccessIterator>(__last), [](_ReferenceType __x, _ReferenceType __y) {
+        using std::swap;
+        swap(__x, __y);
+      });
+}
+
+// this brick is called in parallel version, so we can use iterator arithmetic
+template <class _BidirectionalIterator>
+void __brick_reverse(_BidirectionalIterator __first,
+                     _BidirectionalIterator __last,
+                     _BidirectionalIterator __d_last,
+                     /*is_vector=*/std::false_type) noexcept {
+  for (--__d_last; __first != __last; ++__first, --__d_last) {
+    using std::iter_swap;
+    iter_swap(__first, __d_last);
+  }
+}
+
+// this brick is called in parallel version, so we can use iterator arithmetic
+template <class _RandomAccessIterator>
+void __brick_reverse(_RandomAccessIterator __first,
+                     _RandomAccessIterator __last,
+                     _RandomAccessIterator __d_last,
+                     /*is_vector=*/std::true_type) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
+
+  __unseq_backend::__simd_walk_2(
+      __first,
+      __last - __first,
+      std::reverse_iterator<_RandomAccessIterator>(__d_last),
+      [](_ReferenceType __x, _ReferenceType __y) {
+        using std::swap;
+        swap(__x, __y);
+      });
+}
+
+template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator>
+void __pattern_reverse(
+    _Tag, _ExecutionPolicy&&, _BidirectionalIterator __first, _BidirectionalIterator __last) noexcept {
+  __internal::__brick_reverse(__first, __last, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator>
+void __pattern_reverse(__parallel_tag<_IsVector> __tag,
+                       _ExecutionPolicy&& __exec,
+                       _RandomAccessIterator __first,
+                       _RandomAccessIterator __last) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  __par_backend::__parallel_for(
+      __backend_tag{},
+      std::forward<_ExecutionPolicy>(__exec),
+      __first,
+      __first + (__last - __first) / 2,
+      [__first, __last](_RandomAccessIterator __inner_first, _RandomAccessIterator __inner_last) {
+        __internal::__brick_reverse(__inner_first, __inner_last, __last - (__inner_first - __first), _IsVector{});
+      });
+}
+
+//------------------------------------------------------------------------
+// reverse_copy
+//------------------------------------------------------------------------
+
+template <class _BidirectionalIterator, class _OutputIterator>
+_OutputIterator __brick_reverse_copy(
+    _BidirectionalIterator __first,
+    _BidirectionalIterator __last,
+    _OutputIterator __d_first,
+    /*is_vector=*/std::false_type) noexcept {
+  return std::reverse_copy(__first, __last, __d_first);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2 __brick_reverse_copy(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __d_first,
+    /*is_vector=*/std::true_type) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator1>::reference _ReferenceType1;
+  typedef typename std::iterator_traits<_RandomAccessIterator2>::reference _ReferenceType2;
+
+  return __unseq_backend::__simd_walk_2(
+      std::reverse_iterator<_RandomAccessIterator1>(__last),
+      __last - __first,
+      __d_first,
+      [](_ReferenceType1 __x, _ReferenceType2 __y) { __y = __x; });
+}
+
+template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _OutputIterator>
+_OutputIterator __pattern_reverse_copy(
+    _Tag,
+    _ExecutionPolicy&&,
+    _BidirectionalIterator __first,
+    _BidirectionalIterator __last,
+    _OutputIterator __d_first) noexcept {
+  return __internal::__brick_reverse_copy(__first, __last, __d_first, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2 __pattern_reverse_copy(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __d_first) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  auto __len = __last - __first;
+  __par_backend::__parallel_for(
+      __backend_tag{},
+      std::forward<_ExecutionPolicy>(__exec),
+      __first,
+      __last,
+      [__first, __len, __d_first](_RandomAccessIterator1 __inner_first, _RandomAccessIterator1 __inner_last) {
+        __internal::__brick_reverse_copy(
+            __inner_first, __inner_last, __d_first + (__len - (__inner_last - __first)), _IsVector{});
+      });
+  return __d_first + __len;
+}
+
+//------------------------------------------------------------------------
+// rotate
+//------------------------------------------------------------------------
+template <class _ForwardIterator>
+_ForwardIterator
+__brick_rotate(_ForwardIterator __first,
+               _ForwardIterator __middle,
+               _ForwardIterator __last,
+               /*is_vector=*/std::false_type) noexcept {
+#if defined(_PSTL_CPP11_STD_ROTATE_BROKEN)
+  std::rotate(__first, __middle, __last);
+  return std::next(__first, std::distance(__middle, __last));
+#else
+  return std::rotate(__first, __middle, __last);
+#endif
+}
+
+template <class _RandomAccessIterator>
+_RandomAccessIterator
+__brick_rotate(_RandomAccessIterator __first,
+               _RandomAccessIterator __middle,
+               _RandomAccessIterator __last,
+               /*is_vector=*/std::true_type) noexcept {
+  auto __n                          = __last - __first;
+  auto __m                          = __middle - __first;
+  const _RandomAccessIterator __ret = __first + (__last - __middle);
+
+  bool __is_left = (__m <= __n / 2);
+  if (!__is_left)
+    __m = __n - __m;
+
+  while (__n > 1 && __m > 0) {
+    using std::iter_swap;
+    const auto __m_2 = __m * 2;
+    if (__is_left) {
+      for (; __last - __first >= __m_2; __first += __m) {
+        __unseq_backend::__simd_assign(
+            __first, __m, __first + __m, iter_swap<_RandomAccessIterator, _RandomAccessIterator>);
+      }
+    } else {
+      for (; __last - __first >= __m_2; __last -= __m) {
+        __unseq_backend::__simd_assign(
+            __last - __m, __m, __last - __m_2, iter_swap<_RandomAccessIterator, _RandomAccessIterator>);
+      }
+    }
+    __is_left = !__is_left;
+    __m       = __n % __m;
+    __n       = __last - __first;
+  }
+
+  return __ret;
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator>
+_ForwardIterator __pattern_rotate(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last) noexcept {
+  return __internal::__brick_rotate(__first, __middle, __last, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator>
+_RandomAccessIterator __pattern_rotate(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __middle,
+    _RandomAccessIterator __last) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
+  auto __n = __last - __first;
+  auto __m = __middle - __first;
+  if (__m <= __n / 2) {
+    __par_backend::__buffer<_Tp> __buf(__n - __m);
+    return __internal::__except_handler([&__exec, __n, __m, __first, __middle, __last, &__buf]() {
+      _Tp* __result = __buf.get();
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __middle,
+          __last,
+          [__middle, __result](_RandomAccessIterator __b, _RandomAccessIterator __e) {
+            __internal::__brick_uninitialized_move(__b, __e, __result + (__b - __middle), _IsVector{});
+          });
+
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __first,
+          __middle,
+          [__last, __middle](_RandomAccessIterator __b, _RandomAccessIterator __e) {
+            __internal::__brick_move(__b, __e, __b + (__last - __middle), _IsVector{});
+          });
+
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __result,
+          __result + (__n - __m),
+          [__first, __result](_Tp* __b, _Tp* __e) {
+            __brick_move_destroy()(__b, __e, __first + (__b - __result), _IsVector{});
+          });
+
+      return __first + (__last - __middle);
+    });
+  } else {
+    __par_backend::__buffer<_Tp> __buf(__m);
+    return __internal::__except_handler([&__exec, __n, __m, __first, __middle, __last, &__buf]() {
+      _Tp* __result = __buf.get();
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __first,
+          __middle,
+          [__first, __result](_RandomAccessIterator __b, _RandomAccessIterator __e) {
+            __internal::__brick_uninitialized_move(__b, __e, __result + (__b - __first), _IsVector{});
+          });
+
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __middle,
+          __last,
+          [__first, __middle](_RandomAccessIterator __b, _RandomAccessIterator __e) {
+            __internal::__brick_move(__b, __e, __first + (__b - __middle), _IsVector{});
+          });
+
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __result,
+          __result + __m,
+          [__n, __m, __first, __result](_Tp* __b, _Tp* __e) {
+            __brick_move_destroy()(__b, __e, __first + ((__n - __m) + (__b - __result)), _IsVector{});
+          });
+
+      return __first + (__last - __middle);
+    });
+  }
+}
+
+//------------------------------------------------------------------------
+// rotate_copy
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class _OutputIterator>
+_OutputIterator __brick_rotate_copy(
+    _ForwardIterator __first,
+    _ForwardIterator __middle,
+    _ForwardIterator __last,
+    _OutputIterator __result,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::rotate_copy(__first, __middle, __last, __result);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2 __brick_rotate_copy(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __middle,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result,
+    /*__is_vector=*/std::true_type) noexcept {
+  _RandomAccessIterator2 __res = __internal::__brick_copy(__middle, __last, __result, std::true_type());
+  return __internal::__brick_copy(__first, __middle, __res, std::true_type());
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator>
+_OutputIterator __pattern_rotate_copy(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __middle,
+    _ForwardIterator __last,
+    _OutputIterator __result) noexcept {
+  return __internal::__brick_rotate_copy(__first, __middle, __last, __result, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2>
+_RandomAccessIterator2 __pattern_rotate_copy(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __middle,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __result) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  __par_backend::__parallel_for(
+      __backend_tag{},
+      std::forward<_ExecutionPolicy>(__exec),
+      __first,
+      __last,
+      [__first, __last, __middle, __result](_RandomAccessIterator1 __b, _RandomAccessIterator1 __e) {
+        if (__b > __middle) {
+          __internal::__brick_copy(__b, __e, __result + (__b - __middle), _IsVector{});
+        } else {
+          _RandomAccessIterator2 __new_result = __result + ((__last - __middle) + (__b - __first));
+          if (__e < __middle) {
+            __internal::__brick_copy(__b, __e, __new_result, _IsVector{});
+          } else {
+            __internal::__brick_copy(__b, __middle, __new_result, _IsVector{});
+            __internal::__brick_copy(__middle, __e, __result, _IsVector{});
+          }
+        }
+      });
+  return __result + (__last - __first);
+}
+
+//------------------------------------------------------------------------
+// is_partitioned
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class _UnaryPredicate>
+bool __brick_is_partitioned(_ForwardIterator __first,
+                            _ForwardIterator __last,
+                            _UnaryPredicate __pred,
+                            /*is_vector=*/std::false_type) noexcept {
+  return std::is_partitioned(__first, __last, __pred);
+}
+
+template <class _RandomAccessIterator, class _UnaryPredicate>
+bool __brick_is_partitioned(_RandomAccessIterator __first,
+                            _RandomAccessIterator __last,
+                            _UnaryPredicate __pred,
+                            /*is_vector=*/std::true_type) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type _SizeType;
+  if (__first == __last) {
+    return true;
+  } else {
+    _RandomAccessIterator __result = __unseq_backend::__simd_first(
+        __first, _SizeType(0), __last - __first, [&__pred](_RandomAccessIterator __it, _SizeType __i) {
+          return !__pred(__it[__i]);
+        });
+    if (__result == __last) {
+      return true;
+    } else {
+      ++__result;
+      return !__unseq_backend::__simd_or(__result, __last - __result, __pred);
+    }
+  }
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
+bool __pattern_is_partitioned(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) noexcept {
+  return __internal::__brick_is_partitioned(__first, __last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
+bool __pattern_is_partitioned(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred) {
+  if (__first == __last) {
+    return true;
+  } else {
+    using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+    return __internal::__except_handler([&]() {
+      // State of current range:
+      // broken     - current range is not partitioned by pred
+      // all_true   - all elements in current range satisfy pred
+      // all_false  - all elements in current range don't satisfy pred
+      // true_false - elements satisfy pred are placed before elements that don't satisfy pred
+      enum _ReduceType { __not_init = -1, __broken, __all_true, __all_false, __true_false };
+      _ReduceType __init = __not_init;
+
+      // Array with states that we'll have when state from the left branch is merged with state from the right branch.
+      // State is calculated by formula: new_state = table[left_state * 4 + right_state]
+      _ReduceType __table[] = {
+          __broken,
+          __broken,
+          __broken,
+          __broken,
+          __broken,
+          __all_true,
+          __true_false,
+          __true_false,
+          __broken,
+          __broken,
+          __all_false,
+          __broken,
+          __broken,
+          __broken,
+          __true_false,
+          __broken};
+
+      __init = __par_backend::__parallel_reduce(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __first,
+          __last,
+          __init,
+          [&__pred,
+           &__table](_RandomAccessIterator __i, _RandomAccessIterator __j, _ReduceType __value) -> _ReduceType {
+            if (__value == __broken) {
+              return __broken;
+            }
+            _ReduceType __res = __not_init;
+            // if first element satisfy pred
+            if (__pred(*__i)) {
+              // find first element that don't satisfy pred
+              _RandomAccessIterator __x = __internal::__brick_find_if(__i + 1, __j, std::not_fn(__pred), _IsVector{});
+              if (__x != __j) {
+                // find first element after "x" that satisfy pred
+                _RandomAccessIterator __y = __internal::__brick_find_if(__x + 1, __j, __pred, _IsVector{});
+                // if it was found then range isn't partitioned by pred
+                if (__y != __j) {
+                  return __broken;
+                } else {
+                  __res = __true_false;
+                }
+              } else {
+                __res = __all_true;
+              }
+            } else { // if first element doesn't satisfy pred
+              // then we should find the first element that satisfy pred.
+              // If we found it then range isn't partitioned by pred
+              if (__internal::__brick_find_if(__i + 1, __j, __pred, _IsVector{}) != __j) {
+                return __broken;
+              } else {
+                __res = __all_false;
+              }
+            }
+            // if we have value from left range then we should calculate the result
+            return (__value == -1) ? __res : __table[__value * 4 + __res];
+          },
+
+          [&__table](_ReduceType __val1, _ReduceType __val2) -> _ReduceType {
+            if (__val1 == __broken || __val2 == __broken) {
+              return __broken;
+            }
+            // calculate the result for new big range
+            return __table[__val1 * 4 + __val2];
+          });
+      return __init != __broken;
+    });
+  }
+}
+
+//------------------------------------------------------------------------
+// partition
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class _UnaryPredicate>
+_ForwardIterator __brick_partition(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _UnaryPredicate __pred,
+    /*is_vector=*/std::false_type) noexcept {
+  return std::partition(__first, __last, __pred);
+}
+
+template <class _RandomAccessIterator, class _UnaryPredicate>
+_RandomAccessIterator __brick_partition(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred,
+    /*is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::partition(__first, __last, __pred);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
+_ForwardIterator __pattern_partition(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) noexcept {
+  return __internal::__brick_partition(__first, __last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
+_RandomAccessIterator __pattern_partition(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  // partitioned range: elements before pivot satisfy pred (true part),
+  //                    elements after pivot don't satisfy pred (false part)
+  struct _PartitionRange {
+    _RandomAccessIterator __begin;
+    _RandomAccessIterator __pivot;
+    _RandomAccessIterator __end;
+  };
+
+  return __internal::__except_handler([&]() {
+    _PartitionRange __init{__last, __last, __last};
+
+    // lambda for merging two partitioned ranges to one partitioned range
+    auto __reductor = [&__exec](_PartitionRange __val1, _PartitionRange __val2) -> _PartitionRange {
+      auto __size1     = __val1.__end - __val1.__pivot;
+      auto __size2     = __val2.__pivot - __val2.__begin;
+      auto __new_begin = __val2.__begin - (__val1.__end - __val1.__begin);
+
+      // if all elements in left range satisfy pred then we can move new pivot to pivot of right range
+      if (__val1.__end == __val1.__pivot) {
+        return {__new_begin, __val2.__pivot, __val2.__end};
+      }
+      // if true part of right range greater than false part of left range
+      // then we should swap the false part of left range and last part of true part of right range
+      else if (__size2 > __size1) {
+        __par_backend::__parallel_for(
+            __backend_tag{},
+            std::forward<_ExecutionPolicy>(__exec),
+            __val1.__pivot,
+            __val1.__pivot + __size1,
+            [__val1, __val2, __size1](_RandomAccessIterator __i, _RandomAccessIterator __j) {
+              __internal::__brick_swap_ranges(
+                  __i, __j, (__val2.__pivot - __size1) + (__i - __val1.__pivot), _IsVector{});
+            });
+        return {__new_begin, __val2.__pivot - __size1, __val2.__end};
+      }
+      // else we should swap the first part of false part of left range and true part of right range
+      else {
+        __par_backend::__parallel_for(
+            __backend_tag{},
+            std::forward<_ExecutionPolicy>(__exec),
+            __val1.__pivot,
+            __val1.__pivot + __size2,
+            [__val1, __val2](_RandomAccessIterator __i, _RandomAccessIterator __j) {
+              __internal::__brick_swap_ranges(__i, __j, __val2.__begin + (__i - __val1.__pivot), _IsVector{});
+            });
+        return {__new_begin, __val1.__pivot + __size2, __val2.__end};
+      }
+    };
+
+    _PartitionRange __result = __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        __init,
+        [__pred,
+         __reductor](_RandomAccessIterator __i, _RandomAccessIterator __j, _PartitionRange __value) -> _PartitionRange {
+          // 1. serial partition
+          _RandomAccessIterator __pivot = __internal::__brick_partition(__i, __j, __pred, _IsVector{});
+
+          // 2. merging of two ranges (left and right respectively)
+          return __reductor(__value, {__i, __pivot, __j});
+        },
+        __reductor);
+    return __result.__pivot;
+  });
+}
+
+//------------------------------------------------------------------------
+// stable_partition
+//------------------------------------------------------------------------
+
+template <class _BidirectionalIterator, class _UnaryPredicate>
+_BidirectionalIterator __brick_stable_partition(
+    _BidirectionalIterator __first,
+    _BidirectionalIterator __last,
+    _UnaryPredicate __pred,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::stable_partition(__first, __last, __pred);
+}
+
+template <class _RandomAccessIterator, class _UnaryPredicate>
+_RandomAccessIterator __brick_stable_partition(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred,
+    /*__is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::stable_partition(__first, __last, __pred);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate>
+_BidirectionalIterator __pattern_stable_partition(
+    _Tag,
+    _ExecutionPolicy&&,
+    _BidirectionalIterator __first,
+    _BidirectionalIterator __last,
+    _UnaryPredicate __pred) noexcept {
+  return __internal::__brick_stable_partition(__first, __last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
+_RandomAccessIterator __pattern_stable_partition(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  // partitioned range: elements before pivot satisfy pred (true part),
+  //                    elements after pivot don't satisfy pred (false part)
+  struct _PartitionRange {
+    _RandomAccessIterator __begin;
+    _RandomAccessIterator __pivot;
+    _RandomAccessIterator __end;
+  };
+
+  return __internal::__except_handler([&]() {
+    _PartitionRange __init{__last, __last, __last};
+
+    // lambda for merging two partitioned ranges to one partitioned range
+    auto __reductor = [](_PartitionRange __val1, _PartitionRange __val2) -> _PartitionRange {
+      auto __size1     = __val1.__end - __val1.__pivot;
+      auto __new_begin = __val2.__begin - (__val1.__end - __val1.__begin);
+
+      // if all elements in left range satisfy pred then we can move new pivot to pivot of right range
+      if (__val1.__end == __val1.__pivot) {
+        return {__new_begin, __val2.__pivot, __val2.__end};
+      }
+      // if true part of right range greater than false part of left range
+      // then we should swap the false part of left range and last part of true part of right range
+      else {
+        __internal::__brick_rotate(__val1.__pivot, __val2.__begin, __val2.__pivot, _IsVector{});
+        return {__new_begin, __val2.__pivot - __size1, __val2.__end};
+      }
+    };
+
+    _PartitionRange __result = __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        __init,
+        [&__pred,
+         __reductor](_RandomAccessIterator __i, _RandomAccessIterator __j, _PartitionRange __value) -> _PartitionRange {
+          // 1. serial stable_partition
+          _RandomAccessIterator __pivot = __internal::__brick_stable_partition(__i, __j, __pred, _IsVector{});
+
+          // 2. merging of two ranges (left and right respectively)
+          return __reductor(__value, {__i, __pivot, __j});
+        },
+        __reductor);
+    return __result.__pivot;
+  });
+}
+
+//------------------------------------------------------------------------
+// partition_copy
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2, class _UnaryPredicate>
+std::pair<_OutputIterator1, _OutputIterator2> __brick_partition_copy(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator1 __out_true,
+    _OutputIterator2 __out_false,
+    _UnaryPredicate __pred,
+    /*is_vector=*/std::false_type) noexcept {
+  return std::partition_copy(__first, __last, __out_true, __out_false, __pred);
+}
+
+template <class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _UnaryPredicate>
+std::pair<_RandomAccessIterator2, _RandomAccessIterator3> __brick_partition_copy(
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __out_true,
+    _RandomAccessIterator3 __out_false,
+    _UnaryPredicate __pred,
+    /*is_vector=*/std::true_type) noexcept {
+#if defined(_PSTL_MONOTONIC_PRESENT)
+  return __unseq_backend::__simd_partition_copy(__first, __last - __first, __out_true, __out_false, __pred);
+#else
+  return std::partition_copy(__first, __last, __out_true, __out_false, __pred);
+#endif
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _OutputIterator1,
+          class _OutputIterator2,
+          class _UnaryPredicate>
+std::pair<_OutputIterator1, _OutputIterator2> __pattern_partition_copy(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _OutputIterator1 __out_true,
+    _OutputIterator2 __out_false,
+    _UnaryPredicate __pred) noexcept {
+  return __internal::__brick_partition_copy(
+      __first, __last, __out_true, __out_false, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _UnaryPredicate>
+std::pair<_RandomAccessIterator2, _RandomAccessIterator3> __pattern_partition_copy(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __out_true,
+    _RandomAccessIterator3 __out_false,
+    _UnaryPredicate __pred) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType;
+  typedef std::pair<_DifferenceType, _DifferenceType> _ReturnType;
+  const _DifferenceType __n = __last - __first;
+  if (_DifferenceType(1) < __n) {
+    __par_backend::__buffer<bool> __mask_buf(__n);
+    return __internal::__except_handler([&__exec, __n, __first, __out_true, __out_false, __pred, &__mask_buf]() {
+      bool* __mask = __mask_buf.get();
+      _ReturnType __m{};
+      __par_backend::__parallel_strict_scan(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __n,
+          std::make_pair(_DifferenceType(0), _DifferenceType(0)),
+          [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
+            return __internal::__brick_calc_mask_1<_DifferenceType>(
+                __first + __i, __first + (__i + __len), __mask + __i, __pred, _IsVector{});
+          },
+          [](const _ReturnType& __x, const _ReturnType& __y) -> _ReturnType {
+            return std::make_pair(__x.first + __y.first, __x.second + __y.second);
+          },                                                                       // Combine
+          [=](_DifferenceType __i, _DifferenceType __len, _ReturnType __initial) { // Scan
+            __internal::__brick_partition_by_mask(
+                __first + __i,
+                __first + (__i + __len),
+                __out_true + __initial.first,
+                __out_false + __initial.second,
+                __mask + __i,
+                _IsVector{});
+          },
+          [&__m](_ReturnType __total) { __m = __total; });
+      return std::make_pair(__out_true + __m.first, __out_false + __m.second);
+    });
+  }
+  // trivial sequence - use serial algorithm
+  return __internal::__brick_partition_copy(__first, __last, __out_true, __out_false, __pred, _IsVector{});
+}
+
+//------------------------------------------------------------------------
+// sort
+//------------------------------------------------------------------------
+
+template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsMoveConstructible>
+void __pattern_sort(_Tag,
+                    _ExecutionPolicy&&,
+                    _RandomAccessIterator __first,
+                    _RandomAccessIterator __last,
+                    _Compare __comp,
+                    _IsMoveConstructible) noexcept {
+  std::sort(__first, __last, __comp);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_sort(__parallel_tag<_IsVector> __tag,
+                    _ExecutionPolicy&& __exec,
+                    _RandomAccessIterator __first,
+                    _RandomAccessIterator __last,
+                    _Compare __comp,
+                    /*is_move_constructible=*/std::true_type) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  __internal::__except_handler([&]() {
+    __par_backend::__parallel_stable_sort(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        __comp,
+        [](_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
+          std::sort(__first, __last, __comp);
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// stable_sort
+//------------------------------------------------------------------------
+
+template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_stable_sort(
+    _Tag, _ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) noexcept {
+  std::stable_sort(__first, __last, __comp);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_stable_sort(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  __internal::__except_handler([&]() {
+    __par_backend::__parallel_stable_sort(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        __comp,
+        [](_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
+          std::stable_sort(__first, __last, __comp);
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// partial_sort
+//------------------------------------------------------------------------
+
+template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_partial_sort(
+    _Tag,
+    _ExecutionPolicy&&,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __middle,
+    _RandomAccessIterator __last,
+    _Compare __comp) noexcept {
+  std::partial_sort(__first, __middle, __last, __comp);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_partial_sort(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __middle,
+    _RandomAccessIterator __last,
+    _Compare __comp) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  const auto __n = __middle - __first;
+  if (__n == 0)
+    return;
+
+  __internal::__except_handler([&]() {
+    __par_backend::__parallel_stable_sort(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        __comp,
+        [__n](_RandomAccessIterator __begin, _RandomAccessIterator __end, _Compare __comp) {
+          if (__n < __end - __begin)
+            std::partial_sort(__begin, __begin + __n, __end, __comp);
+          else
+            std::sort(__begin, __end, __comp);
+        },
+        __n);
+  });
+}
+
+//------------------------------------------------------------------------
+// partial_sort_copy
+//------------------------------------------------------------------------
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator, class _Compare>
+_RandomAccessIterator __pattern_partial_sort_copy(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _RandomAccessIterator __d_first,
+    _RandomAccessIterator __d_last,
+    _Compare __comp) noexcept {
+  return std::partial_sort_copy(__first, __last, __d_first, __d_last, __comp);
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _Compare>
+_RandomAccessIterator2 __pattern_partial_sort_copy(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first,
+    _RandomAccessIterator1 __last,
+    _RandomAccessIterator2 __d_first,
+    _RandomAccessIterator2 __d_last,
+    _Compare __comp) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__last == __first || __d_last == __d_first) {
+    return __d_first;
+  }
+  auto __n1 = __last - __first;
+  auto __n2 = __d_last - __d_first;
+  return __internal::__except_handler([&]() {
+    if (__n2 >= __n1) {
+      __par_backend::__parallel_stable_sort(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __d_first,
+          __d_first + __n1,
+          __comp,
+          [__first, __d_first](_RandomAccessIterator2 __i, _RandomAccessIterator2 __j, _Compare __comp) {
+            _RandomAccessIterator1 __i1 = __first + (__i - __d_first);
+            _RandomAccessIterator1 __j1 = __first + (__j - __d_first);
+
+        // 1. Copy elements from input to output
+#if !defined(_PSTL_ICC_18_OMP_SIMD_BROKEN)
+            __internal::__brick_copy(__i1, __j1, __i, _IsVector{});
+#else
+            std::copy(__i1, __j1, __i);
+#endif
+            // 2. Sort elements in output sequence
+            std::sort(__i, __j, __comp);
+          },
+          __n1);
+      return __d_first + __n1;
+    } else {
+      typedef typename std::iterator_traits<_RandomAccessIterator1>::value_type _T1;
+      typedef typename std::iterator_traits<_RandomAccessIterator2>::value_type _T2;
+      __par_backend::__buffer<_T1> __buf(__n1);
+      _T1* __r = __buf.get();
+
+      __par_backend::__parallel_stable_sort(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __r,
+          __r + __n1,
+          __comp,
+          [__n2, __first, __r](_T1* __i, _T1* __j, _Compare __comp) {
+            _RandomAccessIterator1 __it = __first + (__i - __r);
+
+            // 1. Copy elements from input to raw memory
+            for (_T1* __k = __i; __k != __j; ++__k, ++__it) {
+              ::new (__k) _T2(*__it);
+            }
+
+            // 2. Sort elements in temporary __buffer
+            if (__n2 < __j - __i)
+              std::partial_sort(__i, __i + __n2, __j, __comp);
+            else
+              std::sort(__i, __j, __comp);
+          },
+          __n2);
+
+      // 3. Move elements from temporary __buffer to output
+      __par_backend::__parallel_for(
+          __backend_tag{},
+          std::forward<_ExecutionPolicy>(__exec),
+          __r,
+          __r + __n2,
+          [__r, __d_first](_T1* __i, _T1* __j) {
+            __brick_move_destroy()(__i, __j, __d_first + (__i - __r), _IsVector{});
+          });
+      __par_backend::__parallel_for(
+          __backend_tag{}, std::forward<_ExecutionPolicy>(__exec), __r + __n2, __r + __n1, [](_T1* __i, _T1* __j) {
+            __brick_destroy(__i, __j, _IsVector{});
+          });
+
+      return __d_first + __n2;
+    }
+  });
+}
+
+//------------------------------------------------------------------------
+// adjacent_find
+//------------------------------------------------------------------------
+template <class _RandomAccessIterator, class _BinaryPredicate>
+_RandomAccessIterator __brick_adjacent_find(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _BinaryPredicate __pred,
+    /* IsVector = */ std::true_type,
+    bool __or_semantic) noexcept {
+  return __unseq_backend::__simd_adjacent_find(__first, __last, __pred, __or_semantic);
+}
+
+template <class _ForwardIterator, class _BinaryPredicate>
+_ForwardIterator __brick_adjacent_find(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _BinaryPredicate __pred,
+    /* IsVector = */ std::false_type,
+    bool) noexcept {
+  return std::adjacent_find(__first, __last, __pred);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
+_ForwardIterator __pattern_adjacent_find(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _BinaryPredicate __pred,
+    bool __or_semantic) noexcept {
+  return __internal::__brick_adjacent_find(__first, __last, __pred, typename _Tag::__is_vector{}, __or_semantic);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate>
+_RandomAccessIterator __pattern_adjacent_find(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _BinaryPredicate __pred,
+    bool __or_semantic) {
+  if (__last - __first < 2)
+    return __last;
+
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    return __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        __last,
+        [__last, __pred, __or_semantic](
+            _RandomAccessIterator __begin, _RandomAccessIterator __end, _RandomAccessIterator __value)
+            -> _RandomAccessIterator {
+          // TODO: investigate performance benefits from the use of shared variable for the result,
+          // checking (compare_and_swap idiom) its __value at __first.
+          if (__or_semantic && __value < __last) { // found
+            __par_backend::__cancel_execution();
+            return __value;
+          }
+
+          if (__value > __begin) {
+            // modify __end to check the predicate on the boundary __values;
+            // TODO: to use a custom range with boundaries overlapping
+            // TODO: investigate what if we remove "if" below and run algorithm on range [__first, __last-1)
+            // then check the pair [__last-1, __last)
+            if (__end != __last)
+              ++__end;
+
+            // correct the global result iterator if the "brick" returns a local "__last"
+            const _RandomAccessIterator __res =
+                __internal::__brick_adjacent_find(__begin, __end, __pred, _IsVector{}, __or_semantic);
+            if (__res < __end)
+              __value = __res;
+          }
+          return __value;
+        },
+        [](_RandomAccessIterator __x, _RandomAccessIterator __y) -> _RandomAccessIterator {
+          return __x < __y ? __x : __y;
+        } // reduce a __value
+    );
+  });
+}
+
+//------------------------------------------------------------------------
+// nth_element
+//------------------------------------------------------------------------
+
+template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_nth_element(
+    _Tag,
+    _ExecutionPolicy&&,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __nth,
+    _RandomAccessIterator __last,
+    _Compare __comp) noexcept {
+  std::nth_element(__first, __nth, __last, __comp);
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_nth_element(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __nth,
+    _RandomAccessIterator __last,
+    _Compare __comp) noexcept {
+  if (__first == __last || __nth == __last) {
+    return;
+  }
+
+  using std::iter_swap;
+  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
+  _RandomAccessIterator __x;
+  do {
+    __x = __internal::__pattern_partition(
+        __tag, std::forward<_ExecutionPolicy>(__exec), __first + 1, __last, [&__comp, __first](const _Tp& __x) {
+          return __comp(__x, *__first);
+        });
+    --__x;
+    if (__x != __first) {
+      iter_swap(__first, __x);
+    }
+    // if x > nth then our new range for partition is [first, x)
+    if (__x - __nth > 0) {
+      __last = __x;
+    }
+    // if x < nth then our new range for partition is [x, last)
+    else if (__x - __nth < 0) {
+      // if *x == *nth then we can start new partition with x+1
+      if (!__comp(*__nth, *__x) && !__comp(*__x, *__nth)) {
+        ++__x;
+      } else {
+        iter_swap(__nth, __x);
+      }
+      __first = __x;
+    }
+  } while (__x != __nth);
+}
+
+//------------------------------------------------------------------------
+// generate, generate_n
+//------------------------------------------------------------------------
+template <class _RandomAccessIterator, class _Generator>
+void __brick_generate(_RandomAccessIterator __first,
+                      _RandomAccessIterator __last,
+                      _Generator __g,
+                      /* is_vector = */ std::true_type) noexcept {
+  __unseq_backend::__simd_generate_n(__first, __last - __first, __g);
+}
+
+template <class _ForwardIterator, class _Generator>
+void __brick_generate(_ForwardIterator __first,
+                      _ForwardIterator __last,
+                      _Generator __g,
+                      /* is_vector = */ std::false_type) noexcept {
+  std::generate(__first, __last, __g);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Generator>
+void __pattern_generate(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Generator __g) noexcept {
+  __internal::__brick_generate(__first, __last, __g, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Generator>
+_RandomAccessIterator __pattern_generate(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Generator __g) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    __par_backend::__parallel_for(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        [__g](_RandomAccessIterator __begin, _RandomAccessIterator __end) {
+          __internal::__brick_generate(__begin, __end, __g, _IsVector{});
+        });
+    return __last;
+  });
+}
+
+template <class _RandomAccessIterator, class Size, class _Generator>
+_RandomAccessIterator __brick_generate_n(
+    _RandomAccessIterator __first,
+    Size __count,
+    _Generator __g,
+    /* is_vector = */ std::true_type) noexcept {
+  return __unseq_backend::__simd_generate_n(__first, __count, __g);
+}
+
+template <class OutputIterator, class Size, class _Generator>
+OutputIterator
+__brick_generate_n(OutputIterator __first, Size __count, _Generator __g, /* is_vector = */ std::false_type) noexcept {
+  return std::generate_n(__first, __count, __g);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _OutputIterator, class _Size, class _Generator>
+_OutputIterator
+__pattern_generate_n(_Tag, _ExecutionPolicy&&, _OutputIterator __first, _Size __count, _Generator __g) noexcept {
+  return __internal::__brick_generate_n(__first, __count, __g, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Generator>
+_RandomAccessIterator __pattern_generate_n(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _Size __count,
+    _Generator __g) {
+  static_assert(__are_random_access_iterators<_RandomAccessIterator>::value,
+                "Pattern-brick error. Should be a random access iterator.");
+  return __internal::__pattern_generate(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __first + __count, __g);
+}
+
+//------------------------------------------------------------------------
+// remove
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator, class _UnaryPredicate>
+_ForwardIterator __brick_remove_if(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _UnaryPredicate __pred,
+    /* __is_vector = */ std::false_type) noexcept {
+  return std::remove_if(__first, __last, __pred);
+}
+
+template <class _RandomAccessIterator, class _UnaryPredicate>
+_RandomAccessIterator __brick_remove_if(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred,
+    /* __is_vector = */ std::true_type) noexcept {
+#if defined(_PSTL_MONOTONIC_PRESENT)
+  return __unseq_backend::__simd_remove_if(__first, __last - __first, __pred);
+#else
+  return std::remove_if(__first, __last, __pred);
+#endif
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
+_ForwardIterator __pattern_remove_if(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) noexcept {
+  return __internal::__brick_remove_if(__first, __last, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
+_RandomAccessIterator __pattern_remove_if(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _UnaryPredicate __pred) noexcept {
+  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
+
+  if (__first == __last || __first + 1 == __last) {
+    // Trivial sequence - use serial algorithm
+    return __internal::__brick_remove_if(__first, __last, __pred, _IsVector{});
+  }
+
+  return __internal::__remove_elements(
+      __tag,
+      std::forward<_ExecutionPolicy>(__exec),
+      __first,
+      __last,
+      [&__pred](bool* __b, bool* __e, _RandomAccessIterator __it) {
+        __internal::__brick_walk2(
+            __b, __e, __it, [&__pred](bool& __x, _ReferenceType __y) { __x = !__pred(__y); }, _IsVector{});
+      });
+}
+
+//------------------------------------------------------------------------
+// inplace_merge
+//------------------------------------------------------------------------
+template <class _BidirectionalIterator, class _Compare>
+void __brick_inplace_merge(
+    _BidirectionalIterator __first,
+    _BidirectionalIterator __middle,
+    _BidirectionalIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::false_type) noexcept {
+  std::inplace_merge(__first, __middle, __last, __comp);
+}
+
+template <class _RandomAccessIterator, class _Compare>
+void __brick_inplace_merge(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __middle,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::true_type) noexcept {
+  // TODO: vectorize
+  std::inplace_merge(__first, __middle, __last, __comp);
+}
+
+template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _Compare>
+void __pattern_inplace_merge(
+    _Tag,
+    _ExecutionPolicy&&,
+    _BidirectionalIterator __first,
+    _BidirectionalIterator __middle,
+    _BidirectionalIterator __last,
+    _Compare __comp) noexcept {
+  __internal::__brick_inplace_merge(__first, __middle, __last, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+void __pattern_inplace_merge(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __middle,
+    _RandomAccessIterator __last,
+    _Compare __comp) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__first == __last || __first == __middle || __middle == __last) {
+    return;
+  }
+  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
+  auto __n = __last - __first;
+  __par_backend::__buffer<_Tp> __buf(__n);
+  _Tp* __r = __buf.get();
+  __internal::__except_handler([&]() {
+    auto __move_values = [](_RandomAccessIterator __x, _Tp* __z) {
+      __internal::__invoke_if_else(
+          std::is_trivial<_Tp>(),
+          [&]() { *__z = std::move(*__x); },
+          [&]() { ::new (std::addressof(*__z)) _Tp(std::move(*__x)); });
+    };
+
+    auto __move_sequences = [](_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Tp* __first2) {
+      return __internal::__brick_uninitialized_move(__first1, __last1, __first2, _IsVector());
+    };
+
+    __par_backend::__parallel_merge(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __middle,
+        __middle,
+        __last,
+        __r,
+        __comp,
+        [__n, __move_values, __move_sequences](
+            _RandomAccessIterator __f1,
+            _RandomAccessIterator __l1,
+            _RandomAccessIterator __f2,
+            _RandomAccessIterator __l2,
+            _Tp* __f3,
+            _Compare __comp) {
+          (__utils::__serial_move_merge(__n))(
+              __f1, __l1, __f2, __l2, __f3, __comp, __move_values, __move_values, __move_sequences, __move_sequences);
+          return __f3 + (__l1 - __f1) + (__l2 - __f2);
+        });
+    __par_backend::__parallel_for(
+        __backend_tag{}, std::forward<_ExecutionPolicy>(__exec), __r, __r + __n, [__r, __first](_Tp* __i, _Tp* __j) {
+          __brick_move_destroy()(__i, __j, __first + (__i - __r), _IsVector{});
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// includes
+//------------------------------------------------------------------------
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
+bool __pattern_includes(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _Compare __comp) noexcept {
+  return std::includes(__first1, __last1, __first2, __last2, __comp);
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _Compare>
+bool __pattern_includes(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _Compare __comp) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__first2 >= __last2)
+    return true;
+
+  if (__first1 >= __last1 || __comp(*__first2, *__first1) || __comp(*(__last1 - 1), *(__last2 - 1)))
+    return false;
+
+  __first1 = std::lower_bound(__first1, __last1, *__first2, __comp);
+  if (__first1 == __last1)
+    return false;
+
+  if (__last2 - __first2 == 1)
+    return !__comp(*__first1, *__first2) && !__comp(*__first2, *__first1);
+
+  return __internal::__except_handler([&]() {
+    return !__internal::__parallel_or(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first2,
+        __last2,
+        [__first1, __last1, __first2, __last2, &__comp](_RandomAccessIterator2 __i, _RandomAccessIterator2 __j) {
+          _LIBCPP_ASSERT_UNCATEGORIZED(__j > __i, "");
+          //_LIBCPP_ASSERT_UNCATEGORIZED(__j - __i > 1, "");
+
+          // 1. moving boundaries to "consume" subsequence of equal elements
+          auto __is_equal = [&__comp](_RandomAccessIterator2 __a, _RandomAccessIterator2 __b) -> bool {
+            return !__comp(*__a, *__b) && !__comp(*__b, *__a);
+          };
+
+          // 1.1 left bound, case "aaa[aaaxyz...]" - searching "x"
+          if (__i > __first2 && __is_equal(__i, __i - 1)) {
+            // whole subrange continues to content equal elements - return "no op"
+            if (__is_equal(__i, __j - 1))
+              return false;
+
+            __i = std::upper_bound(__i, __last2, *__i, __comp);
+          }
+
+          // 1.2 right bound, case "[...aaa]aaaxyz" - searching "x"
+          if (__j < __last2 && __is_equal(__j - 1, __j))
+            __j = std::upper_bound(__j, __last2, *__j, __comp);
+
+          // 2. testing is __a subsequence of the second range included into the first range
+          auto __b = std::lower_bound(__first1, __last1, *__i, __comp);
+
+          _LIBCPP_ASSERT_UNCATEGORIZED(!__comp(*(__last1 - 1), *__b), "");
+          _LIBCPP_ASSERT_UNCATEGORIZED(!__comp(*(__j - 1), *__i), "");
+          return !std::includes(__b, __last1, __i, __j, __comp);
+        });
+  });
+}
+
+constexpr auto __set_algo_cut_off = 1000;
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _OutputIterator,
+          class _Compare,
+          class _SizeFunction,
+          class _SetOP>
+_OutputIterator __parallel_set_op(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    _SizeFunction __size_func,
+    _SetOP __set_op) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_ForwardIterator1>::difference_type _DifferenceType;
+  typedef typename std::iterator_traits<_OutputIterator>::value_type _Tp;
+
+  struct _SetRange {
+    _DifferenceType __pos, __len, __buf_pos;
+    bool empty() const { return __len == 0; }
+  };
+
+  const _DifferenceType __n1 = __last1 - __first1;
+  const _DifferenceType __n2 = __last2 - __first2;
+
+  __par_backend::__buffer<_Tp> __buf(__size_func(__n1, __n2));
+
+  return __internal::__except_handler(
+      [&__exec, __n1, __first1, __last1, __first2, __last2, __result, __comp, __size_func, __set_op, &__buf]() {
+        auto __buffer = __buf.get();
+        _DifferenceType __m{};
+        auto __scan = [=](_DifferenceType, _DifferenceType, const _SetRange& __s) { // Scan
+          if (!__s.empty())
+            __brick_move_destroy()(
+                __buffer + __s.__buf_pos, __buffer + (__s.__buf_pos + __s.__len), __result + __s.__pos, _IsVector{});
+        };
+        __par_backend::__parallel_strict_scan(
+            __backend_tag{},
+            std::forward<_ExecutionPolicy>(__exec),
+            __n1,
+            _SetRange{0, 0, 0},                               //-1, 0},
+            [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
+              //[__b; __e) - a subrange of the first sequence, to reduce
+              _ForwardIterator1 __b = __first1 + __i, __e = __first1 + (__i + __len);
+
+              // try searching for the first element which not equal to *__b
+              if (__b != __first1)
+                __b = std::upper_bound(__b, __last1, *__b, __comp);
+
+              // try searching for the first element which not equal to *__e
+              if (__e != __last1)
+                __e = std::upper_bound(__e, __last1, *__e, __comp);
+
+              // check is [__b; __e) empty
+              if (__e - __b < 1) {
+                _ForwardIterator2 __bb = __last2;
+                if (__b != __last1)
+                  __bb = std::lower_bound(__first2, __last2, *__b, __comp);
+
+                const _DifferenceType __buf_pos = __size_func((__b - __first1), (__bb - __first2));
+                return _SetRange{0, 0, __buf_pos};
+              }
+
+              // try searching for "corresponding" subrange [__bb; __ee) in the second sequence
+              _ForwardIterator2 __bb = __first2;
+              if (__b != __first1)
+                __bb = std::lower_bound(__first2, __last2, *__b, __comp);
+
+              _ForwardIterator2 __ee = __last2;
+              if (__e != __last1)
+                __ee = std::lower_bound(__bb, __last2, *__e, __comp);
+
+              const _DifferenceType __buf_pos = __size_func((__b - __first1), (__bb - __first2));
+              auto __buffer_b                 = __buffer + __buf_pos;
+              auto __res                      = __set_op(__b, __e, __bb, __ee, __buffer_b, __comp);
+
+              return _SetRange{0, __res - __buffer_b, __buf_pos};
+            },
+            [](const _SetRange& __a, const _SetRange& __b) { // Combine
+              if (__b.__buf_pos > __a.__buf_pos || ((__b.__buf_pos == __a.__buf_pos) && !__b.empty()))
+                return _SetRange{__a.__pos + __a.__len + __b.__pos, __b.__len, __b.__buf_pos};
+              return _SetRange{__b.__pos + __b.__len + __a.__pos, __a.__len, __a.__buf_pos};
+            },
+            __scan,                                     // Scan
+            [&__m, &__scan](const _SetRange& __total) { // Apex
+              // final scan
+              __scan(0, 0, __total);
+              __m = __total.__pos + __total.__len;
+            });
+        return __result + __m;
+      });
+}
+
+// a shared parallel pattern for '__pattern_set_union' and '__pattern_set_symmetric_difference'
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _OutputIterator,
+          class _Compare,
+          class _SetUnionOp>
+_OutputIterator __parallel_set_union_op(
+    _Tag __tag,
+    _ExecutionPolicy&& __exec,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    _SetUnionOp __set_union_op) {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  typedef typename std::iterator_traits<_ForwardIterator1>::difference_type _DifferenceType;
+
+  const auto __n1 = __last1 - __first1;
+  const auto __n2 = __last2 - __first2;
+
+  auto copy_range1 = [](_ForwardIterator1 __begin, _ForwardIterator1 __end, _OutputIterator __res) {
+    return __internal::__brick_copy(__begin, __end, __res, typename _Tag::__is_vector{});
+  };
+  auto copy_range2 = [](_ForwardIterator2 __begin, _ForwardIterator2 __end, _OutputIterator __res) {
+    return __internal::__brick_copy(__begin, __end, __res, typename _Tag::__is_vector{});
+  };
+
+  // {1} {}: parallel copying just first sequence
+  if (__n2 == 0)
+    return __internal::__pattern_walk2_brick(
+        __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result, copy_range1);
+
+  // {} {2}: parallel copying justmake  second sequence
+  if (__n1 == 0)
+    return __internal::__pattern_walk2_brick(
+        __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result, copy_range2);
+
+  // testing  whether the sequences are intersected
+  _ForwardIterator1 __left_bound_seq_1 = std::lower_bound(__first1, __last1, *__first2, __comp);
+
+  if (__left_bound_seq_1 == __last1) {
+    //{1} < {2}: seq2 is wholly greater than seq1, so, do parallel copying seq1 and seq2
+    __par_backend::__parallel_invoke(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        [=] {
+          __internal::__pattern_walk2_brick(
+              __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result, copy_range1);
+        },
+        [=] {
+          __internal::__pattern_walk2_brick(
+              __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result + __n1, copy_range2);
+        });
+    return __result + __n1 + __n2;
+  }
+
+  // testing  whether the sequences are intersected
+  _ForwardIterator2 __left_bound_seq_2 = std::lower_bound(__first2, __last2, *__first1, __comp);
+
+  if (__left_bound_seq_2 == __last2) {
+    //{2} < {1}: seq2 is wholly greater than seq1, so, do parallel copying seq1 and seq2
+    __par_backend::__parallel_invoke(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        [=] {
+          __internal::__pattern_walk2_brick(
+              __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result, copy_range2);
+        },
+        [=] {
+          __internal::__pattern_walk2_brick(
+              __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result + __n2, copy_range1);
+        });
+    return __result + __n1 + __n2;
+  }
+
+  const auto __m1 = __left_bound_seq_1 - __first1;
+  if (__m1 > __set_algo_cut_off) {
+    auto __res_or = __result;
+    __result += __m1; // we know proper offset due to [first1; left_bound_seq_1) < [first2; last2)
+    __par_backend::__parallel_invoke(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        // do parallel copying of [first1; left_bound_seq_1)
+        [=] {
+          __internal::__pattern_walk2_brick(
+              __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __left_bound_seq_1, __res_or, copy_range1);
+        },
+        [=, &__result] {
+          __result = __internal::__parallel_set_op(
+              __tag,
+              std::forward<_ExecutionPolicy>(__exec),
+              __left_bound_seq_1,
+              __last1,
+              __first2,
+              __last2,
+              __result,
+              __comp,
+              [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
+              __set_union_op);
+        });
+    return __result;
+  }
+
+  const auto __m2 = __left_bound_seq_2 - __first2;
+  _LIBCPP_ASSERT_UNCATEGORIZED(__m1 == 0 || __m2 == 0, "");
+  if (__m2 > __set_algo_cut_off) {
+    auto __res_or = __result;
+    __result += __m2; // we know proper offset due to [first2; left_bound_seq_2) < [first1; last1)
+    __par_backend::__parallel_invoke(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        // do parallel copying of [first2; left_bound_seq_2)
+        [=] {
+          __internal::__pattern_walk2_brick(
+              __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __left_bound_seq_2, __res_or, copy_range2);
+        },
+        [=, &__result] {
+          __result = __internal::__parallel_set_op(
+              __tag,
+              std::forward<_ExecutionPolicy>(__exec),
+              __first1,
+              __last1,
+              __left_bound_seq_2,
+              __last2,
+              __result,
+              __comp,
+              [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
+              __set_union_op);
+        });
+    return __result;
+  }
+
+  return __internal::__parallel_set_op(
+      __tag,
+      std::forward<_ExecutionPolicy>(__exec),
+      __first1,
+      __last1,
+      __first2,
+      __last2,
+      __result,
+      __comp,
+      [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
+      __set_union_op);
+}
+
+//------------------------------------------------------------------------
+// set_union
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
+_OutputIterator __brick_set_union(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <typename _IsVector>
+struct __BrickCopyConstruct {
+  template <typename _ForwardIterator, typename _OutputIterator>
+  _OutputIterator operator()(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result) {
+    return __brick_uninitialized_copy(__first, __last, __result, _IsVector());
+  }
+};
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
+_OutputIterator __brick_set_union(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    /*__is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _OutputIterator,
+          class _Compare>
+_OutputIterator __pattern_set_union(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp) noexcept {
+  return __internal::__brick_set_union(
+      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _OutputIterator,
+          class _Compare>
+_OutputIterator __pattern_set_union(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp) {
+  const auto __n1 = __last1 - __first1;
+  const auto __n2 = __last2 - __first2;
+
+  // use serial algorithm
+  if (__n1 + __n2 <= __set_algo_cut_off)
+    return std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
+
+  typedef typename std::iterator_traits<_OutputIterator>::value_type _Tp;
+  return __parallel_set_union_op(
+      __tag,
+      std::forward<_ExecutionPolicy>(__exec),
+      __first1,
+      __last1,
+      __first2,
+      __last2,
+      __result,
+      __comp,
+      [](_RandomAccessIterator1 __first1,
+         _RandomAccessIterator1 __last1,
+         _RandomAccessIterator2 __first2,
+         _RandomAccessIterator2 __last2,
+         _Tp* __result,
+         _Compare __comp) {
+        return __pstl::__utils::__set_union_construct(
+            __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
+      });
+}
+
+//------------------------------------------------------------------------
+// set_intersection
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
+_OutputIterator __brick_set_intersection(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::set_intersection(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
+_RandomAccessIterator3 __brick_set_intersection(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __result,
+    _Compare __comp,
+    /*__is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::set_intersection(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _OutputIterator,
+          class _Compare>
+_OutputIterator __pattern_set_intersection(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp) noexcept {
+  return __internal::__brick_set_intersection(
+      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _Compare>
+_RandomAccessIterator3 __pattern_set_intersection(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __result,
+    _Compare __comp) {
+  typedef typename std::iterator_traits<_RandomAccessIterator3>::value_type _Tp;
+  typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType;
+
+  const auto __n1 = __last1 - __first1;
+  const auto __n2 = __last2 - __first2;
+
+  // intersection is empty
+  if (__n1 == 0 || __n2 == 0)
+    return __result;
+
+  // testing  whether the sequences are intersected
+  _RandomAccessIterator1 __left_bound_seq_1 = std::lower_bound(__first1, __last1, *__first2, __comp);
+  //{1} < {2}: seq 2 is wholly greater than seq 1, so, the intersection is empty
+  if (__left_bound_seq_1 == __last1)
+    return __result;
+
+  // testing  whether the sequences are intersected
+  _RandomAccessIterator2 __left_bound_seq_2 = std::lower_bound(__first2, __last2, *__first1, __comp);
+  //{2} < {1}: seq 1 is wholly greater than seq 2, so, the intersection is empty
+  if (__left_bound_seq_2 == __last2)
+    return __result;
+
+  const auto __m1 = __last1 - __left_bound_seq_1 + __n2;
+  if (__m1 > __set_algo_cut_off) {
+    // we know proper offset due to [first1; left_bound_seq_1) < [first2; last2)
+    return __internal::__parallel_set_op(
+        __tag,
+        std::forward<_ExecutionPolicy>(__exec),
+        __left_bound_seq_1,
+        __last1,
+        __first2,
+        __last2,
+        __result,
+        __comp,
+        [](_DifferenceType __n, _DifferenceType __m) { return std::min(__n, __m); },
+        [](_RandomAccessIterator1 __first1,
+           _RandomAccessIterator1 __last1,
+           _RandomAccessIterator2 __first2,
+           _RandomAccessIterator2 __last2,
+           _Tp* __result,
+           _Compare __comp) {
+          return __pstl::__utils::__set_intersection_construct(__first1, __last1, __first2, __last2, __result, __comp);
+        });
+  }
+
+  const auto __m2 = __last2 - __left_bound_seq_2 + __n1;
+  if (__m2 > __set_algo_cut_off) {
+    // we know proper offset due to [first2; left_bound_seq_2) < [first1; last1)
+    __result = __internal::__parallel_set_op(
+        __tag,
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        __left_bound_seq_2,
+        __last2,
+        __result,
+        __comp,
+        [](_DifferenceType __n, _DifferenceType __m) { return std::min(__n, __m); },
+        [](_RandomAccessIterator1 __first1,
+           _RandomAccessIterator1 __last1,
+           _RandomAccessIterator2 __first2,
+           _RandomAccessIterator2 __last2,
+           _Tp* __result,
+           _Compare __comp) {
+          return __pstl::__utils::__set_intersection_construct(__first2, __last2, __first1, __last1, __result, __comp);
+        });
+    return __result;
+  }
+
+  // [left_bound_seq_1; last1) and [left_bound_seq_2; last2) - use serial algorithm
+  return std::set_intersection(__left_bound_seq_1, __last1, __left_bound_seq_2, __last2, __result, __comp);
+}
+
+//------------------------------------------------------------------------
+// set_difference
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
+_OutputIterator __brick_set_difference(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::set_difference(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
+_RandomAccessIterator3 __brick_set_difference(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __result,
+    _Compare __comp,
+    /*__is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::set_difference(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _OutputIterator,
+          class _Compare>
+_OutputIterator __pattern_set_difference(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp) noexcept {
+  return __internal::__brick_set_difference(
+      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _Compare>
+_RandomAccessIterator3 __pattern_set_difference(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __result,
+    _Compare __comp) {
+  typedef typename std::iterator_traits<_RandomAccessIterator3>::value_type _Tp;
+  typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType;
+
+  const auto __n1 = __last1 - __first1;
+  const auto __n2 = __last2 - __first2;
+
+  // {} \ {2}: the difference is empty
+  if (__n1 == 0)
+    return __result;
+
+  // {1} \ {}: parallel copying just first sequence
+  if (__n2 == 0)
+    return __internal::__pattern_walk2_brick(
+        __tag,
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        __result,
+        [](_RandomAccessIterator1 __begin, _RandomAccessIterator1 __end, _RandomAccessIterator3 __res) {
+          return __internal::__brick_copy(__begin, __end, __res, _IsVector{});
+        });
+
+  // testing  whether the sequences are intersected
+  _RandomAccessIterator1 __left_bound_seq_1 = std::lower_bound(__first1, __last1, *__first2, __comp);
+  //{1} < {2}: seq 2 is wholly greater than seq 1, so, parallel copying just first sequence
+  if (__left_bound_seq_1 == __last1)
+    return __internal::__pattern_walk2_brick(
+        __tag,
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        __result,
+        [](_RandomAccessIterator1 __begin, _RandomAccessIterator1 __end, _RandomAccessIterator3 __res) {
+          return __internal::__brick_copy(__begin, __end, __res, _IsVector{});
+        });
+
+  // testing  whether the sequences are intersected
+  _RandomAccessIterator2 __left_bound_seq_2 = std::lower_bound(__first2, __last2, *__first1, __comp);
+  //{2} < {1}: seq 1 is wholly greater than seq 2, so, parallel copying just first sequence
+  if (__left_bound_seq_2 == __last2)
+    return __internal::__pattern_walk2_brick(
+        __tag,
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        __result,
+        [](_RandomAccessIterator1 __begin, _RandomAccessIterator1 __end, _RandomAccessIterator3 __res) {
+          return __internal::__brick_copy(__begin, __end, __res, _IsVector{});
+        });
+
+  if (__n1 + __n2 > __set_algo_cut_off)
+    return __parallel_set_op(
+        __tag,
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __last1,
+        __first2,
+        __last2,
+        __result,
+        __comp,
+        [](_DifferenceType __n, _DifferenceType) { return __n; },
+        [](_RandomAccessIterator1 __first1,
+           _RandomAccessIterator1 __last1,
+           _RandomAccessIterator2 __first2,
+           _RandomAccessIterator2 __last2,
+           _Tp* __result,
+           _Compare __comp) {
+          return __pstl::__utils::__set_difference_construct(
+              __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
+        });
+
+  // use serial algorithm
+  return std::set_difference(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+//------------------------------------------------------------------------
+// set_symmetric_difference
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
+_OutputIterator __brick_set_symmetric_difference(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp,
+    /*__is_vector=*/std::false_type) noexcept {
+  return std::set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
+_RandomAccessIterator3 __brick_set_symmetric_difference(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __result,
+    _Compare __comp,
+    /*__is_vector=*/std::true_type) noexcept {
+  // TODO: vectorize
+  return std::set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _Tag,
+          class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _OutputIterator,
+          class _Compare>
+_OutputIterator __pattern_set_symmetric_difference(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _OutputIterator __result,
+    _Compare __comp) noexcept {
+  return __internal::__brick_set_symmetric_difference(
+      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _RandomAccessIterator3,
+          class _Compare>
+_RandomAccessIterator3 __pattern_set_symmetric_difference(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _RandomAccessIterator3 __result,
+    _Compare __comp) {
+  const auto __n1 = __last1 - __first1;
+  const auto __n2 = __last2 - __first2;
+
+  // use serial algorithm
+  if (__n1 + __n2 <= __set_algo_cut_off)
+    return std::set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp);
+
+  typedef typename std::iterator_traits<_RandomAccessIterator3>::value_type _Tp;
+  return __internal::__parallel_set_union_op(
+      __tag,
+      std::forward<_ExecutionPolicy>(__exec),
+      __first1,
+      __last1,
+      __first2,
+      __last2,
+      __result,
+      __comp,
+      [](_RandomAccessIterator1 __first1,
+         _RandomAccessIterator1 __last1,
+         _RandomAccessIterator2 __first2,
+         _RandomAccessIterator2 __last2,
+         _Tp* __result,
+         _Compare __comp) {
+        return __pstl::__utils::__set_symmetric_difference_construct(
+            __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
+      });
+}
+
+//------------------------------------------------------------------------
+// is_heap_until
+//------------------------------------------------------------------------
+
+template <class _RandomAccessIterator, class _Compare>
+_RandomAccessIterator __brick_is_heap_until(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::false_type) noexcept {
+  return std::is_heap_until(__first, __last, __comp);
+}
+
+template <class _RandomAccessIterator, class _Compare>
+_RandomAccessIterator __brick_is_heap_until(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::true_type) noexcept {
+  if (__last - __first < 2)
+    return __last;
+  typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type _SizeType;
+  return __unseq_backend::__simd_first(
+      __first, _SizeType(0), __last - __first, [&__comp](_RandomAccessIterator __it, _SizeType __i) {
+        return __comp(__it[(__i - 1) / 2], __it[__i]);
+      });
+}
+
+template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+_RandomAccessIterator __pattern_is_heap_until(
+    _Tag, _ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) noexcept {
+  return __internal::__brick_is_heap_until(__first, __last, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
+_RandomAccessIterator __is_heap_until_local(
+    _RandomAccessIterator __first,
+    _DifferenceType __begin,
+    _DifferenceType __end,
+    _Compare __comp,
+    /* __is_vector = */ std::false_type) noexcept {
+  _DifferenceType __i = __begin;
+  for (; __i < __end; ++__i) {
+    if (__comp(__first[(__i - 1) / 2], __first[__i])) {
+      break;
+    }
+  }
+  return __first + __i;
+}
+
+template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
+_RandomAccessIterator __is_heap_until_local(
+    _RandomAccessIterator __first,
+    _DifferenceType __begin,
+    _DifferenceType __end,
+    _Compare __comp,
+    /* __is_vector = */ std::true_type) noexcept {
+  return __unseq_backend::__simd_first(
+      __first, __begin, __end, [&__comp](_RandomAccessIterator __it, _DifferenceType __i) {
+        return __comp(__it[(__i - 1) / 2], __it[__i]);
+      });
+}
+
+template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
+_RandomAccessIterator __pattern_is_heap_until(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__last - __first < 2)
+    return __last;
+
+  return __internal::__except_handler([&]() {
+    return __parallel_find(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first,
+        __last,
+        [__first, __comp](_RandomAccessIterator __i, _RandomAccessIterator __j) {
+          return __internal::__is_heap_until_local(__first, __i - __first, __j - __first, __comp, _IsVector{});
+        },
+        std::less<typename std::iterator_traits<_RandomAccessIterator>::difference_type>(),
+        /*is_first=*/true);
+  });
+}
+
+//------------------------------------------------------------------------
+// min_element
+//------------------------------------------------------------------------
+
+template <typename _ForwardIterator, typename _Compare>
+_ForwardIterator __brick_min_element(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::false_type) noexcept {
+  return std::min_element(__first, __last, __comp);
+}
+
+template <typename _RandomAccessIterator, typename _Compare>
+_RandomAccessIterator __brick_min_element(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::true_type) noexcept {
+#if defined(_PSTL_UDR_PRESENT)
+  return __unseq_backend::__simd_min_element(__first, __last - __first, __comp);
+#else
+  return std::min_element(__first, __last, __comp);
+#endif
+}
+
+template <typename _Tag, typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare>
+_ForwardIterator __pattern_min_element(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) noexcept {
+  return __internal::__brick_min_element(__first, __last, __comp, typename _Tag::__is_vector{});
+}
+
+template <typename _IsVector, typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare>
+_RandomAccessIterator __pattern_min_element(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp) {
+  if (__first == __last)
+    return __last;
+
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    return __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first + 1,
+        __last,
+        __first,
+        [=](_RandomAccessIterator __begin, _RandomAccessIterator __end, _RandomAccessIterator __init)
+            -> _RandomAccessIterator {
+          const _RandomAccessIterator subresult = __internal::__brick_min_element(__begin, __end, __comp, _IsVector{});
+          return __internal::__cmp_iterators_by_values(__init, subresult, __comp);
+        },
+        [=](_RandomAccessIterator __it1, _RandomAccessIterator __it2) -> _RandomAccessIterator {
+          return __internal::__cmp_iterators_by_values(__it1, __it2, __comp);
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// minmax_element
+//------------------------------------------------------------------------
+
+template <typename _ForwardIterator, typename _Compare>
+std::pair<_ForwardIterator, _ForwardIterator> __brick_minmax_element(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::false_type) noexcept {
+  return std::minmax_element(__first, __last, __comp);
+}
+
+template <typename _RandomAccessIterator, typename _Compare>
+std::pair<_RandomAccessIterator, _RandomAccessIterator> __brick_minmax_element(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    /* __is_vector = */ std::true_type) noexcept {
+#if defined(_PSTL_UDR_PRESENT)
+  return __unseq_backend::__simd_minmax_element(__first, __last - __first, __comp);
+#else
+  return std::minmax_element(__first, __last, __comp);
+#endif
+}
+
+template <typename _Tag, typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare>
+std::pair<_ForwardIterator, _ForwardIterator> __pattern_minmax_element(
+    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) noexcept {
+  return __internal::__brick_minmax_element(__first, __last, __comp, typename _Tag::__is_vector{});
+}
+
+template <typename _IsVector, typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare>
+std::pair<_RandomAccessIterator, _RandomAccessIterator> __pattern_minmax_element(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp) {
+  if (__first == __last)
+    return std::make_pair(__first, __first);
+
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    typedef std::pair<_RandomAccessIterator, _RandomAccessIterator> _Result;
+
+    return __par_backend::__parallel_reduce(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first + 1,
+        __last,
+        std::make_pair(__first, __first),
+        [=](_RandomAccessIterator __begin, _RandomAccessIterator __end, _Result __init) -> _Result {
+          const _Result __subresult = __internal::__brick_minmax_element(__begin, __end, __comp, _IsVector{});
+          return std::make_pair(
+              __internal::__cmp_iterators_by_values(__subresult.first, __init.first, __comp),
+              __internal::__cmp_iterators_by_values(__init.second, __subresult.second, std::not_fn(__comp)));
+        },
+        [=](_Result __p1, _Result __p2) -> _Result {
+          return std::make_pair(__internal::__cmp_iterators_by_values(__p1.first, __p2.first, __comp),
+                                __internal::__cmp_iterators_by_values(__p2.second, __p1.second, std::not_fn(__comp)));
+        });
+  });
+}
+
+//------------------------------------------------------------------------
+// mismatch
+//------------------------------------------------------------------------
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+std::pair<_ForwardIterator1, _ForwardIterator2> __mismatch_serial(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _BinaryPredicate __pred) {
+  return std::mismatch(__first1, __last1, __first2, __last2, __pred);
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
+std::pair<_ForwardIterator1, _ForwardIterator2> __brick_mismatch(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _Predicate __pred,
+    /* __is_vector = */ std::false_type) noexcept {
+  return __mismatch_serial(__first1, __last1, __first2, __last2, __pred);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Predicate>
+std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __brick_mismatch(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _Predicate __pred,
+    /* __is_vector = */ std::true_type) noexcept {
+  auto __n = std::min(__last1 - __first1, __last2 - __first2);
+  return __unseq_backend::__simd_first(__first1, __n, __first2, std::not_fn(__pred));
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
+std::pair<_ForwardIterator1, _ForwardIterator2> __pattern_mismatch(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _Predicate __pred) noexcept {
+  return __internal::__brick_mismatch(__first1, __last1, __first2, __last2, __pred, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _Predicate>
+std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __pattern_mismatch(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _Predicate __pred) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  return __internal::__except_handler([&]() {
+    auto __n      = std::min(__last1 - __first1, __last2 - __first2);
+    auto __result = __internal::__parallel_find(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __first1 + __n,
+        [__first1, __first2, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          return __internal::__brick_mismatch(
+                     __i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1), __pred, _IsVector{})
+              .first;
+        },
+        std::less<typename std::iterator_traits<_RandomAccessIterator1>::difference_type>(),
+        /*is_first=*/true);
+    return std::make_pair(__result, __first2 + (__result - __first1));
+  });
+}
+
+//------------------------------------------------------------------------
+// lexicographical_compare
+//------------------------------------------------------------------------
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _Compare>
+bool __brick_lexicographical_compare(
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _Compare __comp,
+    /* __is_vector = */ std::false_type) noexcept {
+  return std::lexicographical_compare(__first1, __last1, __first2, __last2, __comp);
+}
+
+template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Compare>
+bool __brick_lexicographical_compare(
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _Compare __comp,
+    /* __is_vector = */ std::true_type) noexcept {
+  if (__first2 == __last2) { // if second sequence is empty
+    return false;
+  } else if (__first1 == __last1) { // if first sequence is empty
+    return true;
+  } else {
+    typedef typename std::iterator_traits<_RandomAccessIterator1>::reference ref_type1;
+    typedef typename std::iterator_traits<_RandomAccessIterator2>::reference ref_type2;
+    --__last1;
+    --__last2;
+    auto __n = std::min(__last1 - __first1, __last2 - __first2);
+    std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __result = __unseq_backend::__simd_first(
+        __first1, __n, __first2, [__comp](const ref_type1 __x, const ref_type2 __y) mutable {
+          return __comp(__x, __y) || __comp(__y, __x);
+        });
+
+    if (__result.first == __last1 && __result.second != __last2) { // if first sequence shorter than second
+      return !__comp(*__result.second, *__result.first);
+    } else { // if second sequence shorter than first or both have the same number of elements
+      return __comp(*__result.first, *__result.second);
+    }
+  }
+}
+
+template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
+bool __pattern_lexicographical_compare(
+    _Tag,
+    _ExecutionPolicy&&,
+    _ForwardIterator1 __first1,
+    _ForwardIterator1 __last1,
+    _ForwardIterator2 __first2,
+    _ForwardIterator2 __last2,
+    _Compare __comp) noexcept {
+  return __internal::__brick_lexicographical_compare(
+      __first1, __last1, __first2, __last2, __comp, typename _Tag::__is_vector{});
+}
+
+template <class _IsVector,
+          class _ExecutionPolicy,
+          class _RandomAccessIterator1,
+          class _RandomAccessIterator2,
+          class _Compare>
+bool __pattern_lexicographical_compare(
+    __parallel_tag<_IsVector> __tag,
+    _ExecutionPolicy&& __exec,
+    _RandomAccessIterator1 __first1,
+    _RandomAccessIterator1 __last1,
+    _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2,
+    _Compare __comp) noexcept {
+  using __backend_tag = typename decltype(__tag)::__backend_tag;
+
+  if (__first2 == __last2) { // if second sequence is empty
+    return false;
+  } else if (__first1 == __last1) { // if first sequence is empty
+    return true;
+  } else {
+    typedef typename std::iterator_traits<_RandomAccessIterator1>::reference _RefType1;
+    typedef typename std::iterator_traits<_RandomAccessIterator2>::reference _RefType2;
+    --__last1;
+    --__last2;
+    auto __n      = std::min(__last1 - __first1, __last2 - __first2);
+    auto __result = __internal::__parallel_find(
+        __backend_tag{},
+        std::forward<_ExecutionPolicy>(__exec),
+        __first1,
+        __first1 + __n,
+        [__first1, __first2, &__comp](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
+          return __internal::__brick_mismatch(
+                     __i,
+                     __j,
+                     __first2 + (__i - __first1),
+                     __first2 + (__j - __first1),
+                     [&__comp](const _RefType1 __x, const _RefType2 __y) {
+                       return !__comp(__x, __y) && !__comp(__y, __x);
+                     },
+                     _IsVector{})
+              .first;
+        },
+        std::less<typename std::iterator_traits<_RandomAccessIterator1>::difference_type>(),
+        /*is_first=*/true);
+
+    if (__result == __last1 && __first2 + (__result - __first1) != __last2) { // if first sequence shorter than second
+      return !__comp(*(__first2 + (__result - __first1)), *__result);
+    } else { // if second sequence shorter than first or both have the same number of elements
+      return __comp(*__result, *(__first2 + (__result - __first1)));
+    }
+  }
+}
+
+} // namespace __internal
+} // namespace __pstl
+
+#endif /* _PSTL_ALGORITHM_IMPL_H */