[libc++][PSTL] Implement std::sort

Reviewed By: #libc, ldionne

Spies: ldionne, libcxx-commits, mgrang

Differential Revision: https://reviews.llvm.org/D152860

8 files changed, 205 insertions, 1 deletions

diff --git a/libcxx/docs/Status/PSTLPaper.csv b/libcxx/docs/Status/PSTLPaper.csv
index d2a51a3..ad18f80 100644
--- a/libcxx/docs/Status/PSTLPaper.csv
+++ b/libcxx/docs/Status/PSTLPaper.csv
@@ -62,7 +62,7 @@ Section,Description,Assignee,Complete
 | `[alg.set.operations] <https://wg21.link/alg.set.operations>`_,std::set_intersection,Nikolas Klauser,|Not Started|
 | `[alg.set.operations] <https://wg21.link/alg.set.operations>`_,std::set_symmetric_difference,Nikolas Klauser,|Not Started|
 | `[alg.set.operations] <https://wg21.link/alg.set.operations>`_,std::set_union,Nikolas Klauser,|Not Started|
-| `[alg.sort] <https://wg21.link/alg.sort>`_,std::sort,Nikolas Klauser,|Not Started|
+| `[alg.sort] <https://wg21.link/alg.sort>`_,std::sort,Nikolas Klauser,|Complete|
 | `[alg.partitions] <https://wg21.link/alg.partitions>`_,std::stable_partition,Nikolas Klauser,|Not Started|
 | `[alg.sort] <https://wg21.link/alg.sort>`_,std::stable_sort,Nikolas Klauser,|Complete|
 | `[alg.swap] <https://wg21.link/alg.swap>`_,std::swap_ranges,Nikolas Klauser,|Not Started|
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index b7c15a2..2bba97f 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -95,6 +95,7 @@ set(files
   __algorithm/pstl_is_partitioned.h
   __algorithm/pstl_merge.h
   __algorithm/pstl_replace.h
+  __algorithm/pstl_sort.h
   __algorithm/pstl_stable_sort.h
   __algorithm/pstl_transform.h
   __algorithm/push_heap.h
diff --git a/libcxx/include/__algorithm/pstl_backend.h b/libcxx/include/__algorithm/pstl_backend.h
index 4d02135..93372f0 100644
--- a/libcxx/include/__algorithm/pstl_backend.h
+++ b/libcxx/include/__algorithm/pstl_backend.h
@@ -150,6 +150,9 @@ implemented, all the algorithms will eventually forward to the basis algorithms
                               _Pred __pred,
                               const _Tp& __new_value);
 
+  template <class _ExecutionPolicy, class _Iterator, class _Comp>
+  void __pstl_sort(_Backend, _Iterator __first, _Iterator __last, _Comp __comp);
+
 // TODO: Complete this list
 
 */
diff --git a/libcxx/include/__algorithm/pstl_sort.h b/libcxx/include/__algorithm/pstl_sort.h
new file mode 100644
index 0000000..8151495
--- /dev/null
+++ b/libcxx/include/__algorithm/pstl_sort.h
@@ -0,0 +1,62 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PSTL_SORT_H
+#define _LIBCPP___ALGORITHM_PSTL_SORT_H
+
+#include <__algorithm/pstl_backend.h>
+#include <__algorithm/pstl_frontend_dispatch.h>
+#include <__algorithm/pstl_stable_sort.h>
+#include <__config>
+#include <__functional/operations.h>
+#include <__type_traits/is_execution_policy.h>
+#include <__type_traits/remove_cvref.h>
+#include <__utility/forward.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class>
+void __pstl_sort();
+
+template <class _ExecutionPolicy,
+          class _RandomAccessIterator,
+          class _Comp,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI void
+sort(_ExecutionPolicy&& __policy, _RandomAccessIterator __first, _RandomAccessIterator __last, _Comp __comp) {
+  std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_sort),
+      [&__policy](_RandomAccessIterator __g_first, _RandomAccessIterator __g_last, _Comp __g_comp) {
+        std::stable_sort(__policy, std::move(__g_first), std::move(__g_last), std::move(__g_comp));
+      },
+      std::move(__first),
+      std::move(__last),
+      std::move(__comp));
+}
+
+template <class _ExecutionPolicy,
+          class _RandomAccessIterator,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI void
+sort(_ExecutionPolicy&& __policy, _RandomAccessIterator __first, _RandomAccessIterator __last) {
+  std::sort(std::forward<_ExecutionPolicy>(__policy), std::move(__first), std::move(__last), less{});
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
+
+#endif // _LIBCPP___ALGORITHM_PSTL_SORT_H
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 35cfc1d..76e0d22 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -1818,6 +1818,7 @@ template <class BidirectionalIterator, class Compare>
 #include <__algorithm/pstl_is_partitioned.h>
 #include <__algorithm/pstl_merge.h>
 #include <__algorithm/pstl_replace.h>
+#include <__algorithm/pstl_sort.h>
 #include <__algorithm/pstl_stable_sort.h>
 #include <__algorithm/pstl_transform.h>
 #include <__algorithm/push_heap.h>
diff --git a/libcxx/test/libcxx/algorithms/pstl.robust_against_customization_points_not_working.pass.cpp b/libcxx/test/libcxx/algorithms/pstl.robust_against_customization_points_not_working.pass.cpp
index 4abd0ed..919945f 100644
--- a/libcxx/test/libcxx/algorithms/pstl.robust_against_customization_points_not_working.pass.cpp
+++ b/libcxx/test/libcxx/algorithms/pstl.robust_against_customization_points_not_working.pass.cpp
@@ -225,6 +225,22 @@ __pstl_reduce(TestBackend, ForwardIterator, ForwardIterator) {
   return {};
 }
 
+bool pstl_sort_called = false;
+
+template <class, class RandomAccessIterator, class Comp>
+void __pstl_sort(TestBackend, RandomAccessIterator, RandomAccessIterator, Comp) {
+  assert(!pstl_sort_called);
+  pstl_sort_called = true;
+}
+
+bool pstl_stable_sort_called = false;
+
+template <class, class RandomAccessIterator, class Comp>
+void __pstl_stable_sort(TestBackend, RandomAccessIterator, RandomAccessIterator, Comp) {
+  assert(!pstl_stable_sort_called);
+  pstl_stable_sort_called = true;
+}
+
 bool pstl_unary_transform_reduce_called = false;
 
 template <class, class ForwardIterator, class T, class UnaryOperation, class BinaryOperation>
@@ -314,6 +330,10 @@ int main(int, char**) {
   assert(std::pstl_reduce_with_init_called);
   (void)std::reduce(TestPolicy{}, std::begin(a), std::end(a));
   assert(std::pstl_reduce_without_init_called);
+  (void)std::sort(TestPolicy{}, std::begin(a), std::end(a));
+  assert(std::pstl_sort_called);
+  (void)std::stable_sort(TestPolicy{}, std::begin(a), std::end(a));
+  assert(std::pstl_stable_sort_called);
   (void)std::transform_reduce(TestPolicy{}, std::begin(a), std::end(a), 0, pred, pred);
   assert(std::pstl_unary_transform_reduce_called);
   (void)std::transform_reduce(TestPolicy{}, std::begin(a), std::end(a), std::begin(a), 0, pred, pred);
diff --git a/libcxx/test/std/algorithms/alg.sorting/alg.sort/sort/pstl.sort.pass.cpp b/libcxx/test/std/algorithms/alg.sorting/alg.sort/sort/pstl.sort.pass.cpp
new file mode 100644
index 0000000..ecde996
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.sorting/alg.sort/sort/pstl.sort.pass.cpp
@@ -0,0 +1,113 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14
+
+// UNSUPPORTED: libcpp-has-no-incomplete-pstl
+
+// template<class ExecutionPolicy, class RandomAccessIterator>
+//   void sort(ExecutionPolicy&& exec,
+//             RandomAccessIterator first, RandomAccessIterator last);
+//
+// template<class ExecutionPolicy, class RandomAccessIterator, class Compare>
+//   void sort(ExecutionPolicy&& exec,
+//             RandomAccessIterator first, RandomAccessIterator last,
+//             Compare comp);
+
+#include <algorithm>
+#include <cassert>
+#include <numeric>
+#include <random>
+#include <vector>
+
+#include "test_execution_policies.h"
+#include "test_iterators.h"
+#include "test_macros.h"
+
+template <class Iter>
+struct Test {
+  template <class ExecutionPolicy>
+  void operator()(ExecutionPolicy&& policy) {
+    { // simple test
+      int in[]       = {1, 2, 3, 2, 6, 4};
+      int expected[] = {1, 2, 2, 3, 4, 6};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // empty range works
+      int in[]       = {1, 2, 3, 2, 6, 4};
+      int expected[] = {1, 2, 3, 2, 6, 4};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::begin(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // single element range works
+      int in[]       = {1};
+      int expected[] = {1};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::begin(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // two element range works
+      int in[]       = {2, 1};
+      int expected[] = {1, 2};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // three element range works
+      int in[]       = {2, 1, 4};
+      int expected[] = {1, 2, 4};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // longer range works
+      int in[]       = {2, 1, 4, 4, 7, 2, 4, 1, 6};
+      int expected[] = {1, 1, 2, 2, 4, 4, 4, 6, 7};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // already sorted
+      int in[]       = {1, 1, 2, 2, 4, 4, 4, 6, 7};
+      int expected[] = {1, 1, 2, 2, 4, 4, 4, 6, 7};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // reversed
+      int in[]       = {7, 6, 4, 4, 4, 2, 2, 1, 1};
+      int expected[] = {1, 1, 2, 2, 4, 4, 4, 6, 7};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // repeating pattern
+      int in[]       = {1, 2, 3, 1, 2, 3, 1, 2, 3};
+      int expected[] = {1, 1, 1, 2, 2, 2, 3, 3, 3};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)));
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+    { // a custom comparator is used
+      int in[]       = {1, 2, 3, 2, 6, 4};
+      int expected[] = {6, 4, 3, 2, 2, 1};
+      std::sort(policy, Iter(std::begin(in)), Iter(std::end(in)), std::greater{});
+      assert(std::equal(std::begin(in), std::end(in), std::begin(expected)));
+    }
+#ifndef TEST_HAS_NO_RANDOM_DEVICE
+    { // large range
+      std::vector<int> vec(300);
+      std::iota(std::begin(vec), std::end(vec), 0);
+      auto expected = vec;
+      std::shuffle(std::begin(vec), std::end(vec), std::mt19937_64(std::random_device{}()));
+      std::sort(Iter(std::data(vec)), Iter(std::data(vec) + std::size(vec)));
+      assert(vec == expected);
+    }
+#endif
+  }
+};
+
+int main(int, char**) {
+  types::for_each(types::random_access_iterator_list<int*>{}, TestIteratorWithPolicies<Test>{});
+
+  return 0;
+}
diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
index 62bd85e..80cf600 100644
--- a/libcxx/test/support/test_macros.h
+++ b/libcxx/test/support/test_macros.h
@@ -398,6 +398,10 @@ inline void DoNotOptimize(Tp const& value) {
 #  define TEST_HAS_NO_C8RTOMB_MBRTOC8
 #endif
 
+#if defined(_LIBCPP_HAS_NO_RANDOM_DEVICE)
+#  define TEST_HAS_NO_RANDOM_DEVICE
+#endif
+
 #if defined(TEST_COMPILER_CLANG)
 #  define TEST_DIAGNOSTIC_PUSH _Pragma("clang diagnostic push")
 #  define TEST_DIAGNOSTIC_POP _Pragma("clang diagnostic pop")