[libc++][ranges] Implement ranges::sort.

Differential Revision: https://reviews.llvm.org/D127557

libcxx/benchmarks/CMakeLists.txt

@@ -166,6 +166,7 @@ set(BENCHMARK_TESTS
     algorithms/min_max_element.bench.cpp
     algorithms/pop_heap.bench.cpp
     algorithms/push_heap.bench.cpp
+    algorithms/ranges_sort.bench.cpp
     algorithms/sort.bench.cpp
     algorithms/sort_heap.bench.cpp
     algorithms/stable_sort.bench.cpp

libcxx/benchmarks/algorithms/ranges_sort.bench.cpp

@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include <algorithm>
+
+#include "common.h"
+
+namespace {
+template <class ValueType, class Order>
+struct Sort {
+  size_t Quantity;
+
+  void run(benchmark::State& state) const {
+    runOpOnCopies<ValueType>(
+        state, Quantity, Order(), BatchSize::CountElements,
+        [](auto& Copy) { std::ranges::sort(Copy); });
+  }
+
+  bool skip() const { return Order() == ::Order::Heap; }
+
+  std::string name() const {
+    return "BM_RangesSort" + ValueType::name() + Order::name() + "_" +
+           std::to_string(Quantity);
+  }
+};
+} // namespace
+
+int main(int argc, char** argv) {
+  benchmark::Initialize(&argc, argv);
+  if (benchmark::ReportUnrecognizedArguments(argc, argv))
+    return 1;
+  makeCartesianProductBenchmark<Sort, AllValueTypes, AllOrders>(Quantities);
+  benchmark::RunSpecifiedBenchmarks();
+}

libcxx/docs/Status/RangesAlgorithms.csv

@@ -73,7 +73,7 @@ Permutation,shuffle,Not assigned,n/a,Not started
 Permutation,unique,Not assigned,n/a,Not started
 Permutation,partition,Not assigned,n/a,Not started
 Permutation,stable_partition,Not assigned,n/a,Not started
-Permutation,sort,Konstantin Varlamov,n/a,In progress
+Permutation,sort,`D127557 <https://llvm.org/D127557>`_,Konstantin Varlamov,✅
 Permutation,stable_sort,Konstantin Varlamov,n/a,In progress
 Permutation,partial_sort,Konstantin Varlamov,n/a,In progress
 Permutation,nth_element,Not assigned,n/a,Not started

libcxx/include/CMakeLists.txt

@@ -45,6 +45,7 @@ set(files
   __algorithm/lexicographical_compare.h
   __algorithm/lower_bound.h
   __algorithm/make_heap.h
+  __algorithm/make_projected.h
   __algorithm/max.h
   __algorithm/max_element.h
   __algorithm/merge.h
@@ -102,6 +103,7 @@ set(files
   __algorithm/ranges_replace.h
   __algorithm/ranges_replace_if.h
   __algorithm/ranges_reverse.h
+  __algorithm/ranges_sort.h
   __algorithm/ranges_swap_ranges.h
   __algorithm/ranges_transform.h
   __algorithm/ranges_upper_bound.h

libcxx/include/__algorithm/make_projected.h

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_MAKE_PROJECTED_H
+#define _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
+
+#include <__concepts/same_as.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__utility/forward.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+
+template <class _Comp, class _Proj>
+_LIBCPP_HIDE_FROM_ABI constexpr static
+decltype(auto) __make_projected_comp(_Comp& __comp, _Proj& __proj) {
+  if constexpr (same_as<_Proj, identity>) {
+    // Avoid creating the lambda and just use the pristine comparator -- for certain algorithms, this would enable
+    // optimizations that rely on the type of the comparator.
+    return __comp;
+
+  } else {
+    return [&](auto&& __lhs, auto&& __rhs) {
+      return std::invoke(__comp,
+                        std::invoke(__proj, std::forward<decltype(__lhs)>(__lhs)),
+                        std::invoke(__proj, std::forward<decltype(__rhs)>(__rhs)));
+    };
+  }
+}
+
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_MAKE_PROJECTED_H

libcxx/include/__algorithm/ranges_sort.h

@@ -0,0 +1,79 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_RANGES_SORT_H
+#define _LIBCPP___ALGORITHM_RANGES_SORT_H
+
+#include <__algorithm/make_projected.h>
+#include <__algorithm/sort.h>
+#include <__concepts/same_as.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <__iterator/projected.h>
+#include <__iterator/sortable.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+namespace __sort {
+
+struct __fn {
+  template <class _Iter, class _Sent, class _Comp, class _Proj>
+  _LIBCPP_HIDE_FROM_ABI constexpr static
+  _Iter __sort_fn_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
+    auto __last_iter = ranges::next(__first, __last);
+
+    auto&& __projected_comp = __make_projected_comp(__comp, __proj);
+    std::__sort_impl(std::move(__first), __last_iter, __projected_comp);
+
+    return __last_iter;
+  }
+
+  template <random_access_iterator _Iter, sentinel_for<_Iter> _Sent, class _Comp = ranges::less, class _Proj = identity>
+    requires sortable<_Iter, _Comp, _Proj>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  _Iter operator()(_Iter __first, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
+    return __sort_fn_impl(std::move(__first), std::move(__last), __comp, __proj);
+  }
+
+  template <random_access_range _Range, class _Comp = ranges::less, class _Proj = identity>
+    requires sortable<iterator_t<_Range>, _Comp, _Proj>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  borrowed_iterator_t<_Range> operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
+    return __sort_fn_impl(ranges::begin(__r), ranges::end(__r), __comp, __proj);
+  }
+};
+
+} // namespace __sort
+
+inline namespace __cpo {
+  inline constexpr auto sort = __sort::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_SORT_H

libcxx/include/__algorithm/sort.h

@@ -18,6 +18,7 @@
 #include <__config>
 #include <__debug>
 #include <__functional/operations.h>
+#include <__functional/ranges_operations.h>
 #include <__iterator/iterator_traits.h>
 #include <__utility/swap.h>
 #include <climits>
@@ -115,6 +116,7 @@ _LIBCPP_HIDDEN unsigned __sort5(_ForwardIterator __x1, _ForwardIterator __x2, _F
   return __r;
 }
 
+// The comparator being simple is a prerequisite for using the branchless optimization.
 template <class _Tp>
 struct __is_simple_comparator : false_type {};
 template <class _Tp>
@@ -123,6 +125,12 @@ template <class _Tp>
 struct __is_simple_comparator<less<_Tp>&> : true_type {};
 template <class _Tp>
 struct __is_simple_comparator<greater<_Tp>&> : true_type {};
+#if _LIBCPP_STD_VER > 17
+template <>
+struct __is_simple_comparator<ranges::less&> : true_type {};
+template <>
+struct __is_simple_comparator<ranges::greater&> : true_type {};
+#endif
 
 template <class _Compare, class _Iter, class _Tp = typename iterator_traits<_Iter>::value_type>
 using __use_branchless_sort =
@@ -571,22 +579,28 @@ extern template _LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long do
 
 extern template _LIBCPP_FUNC_VIS unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&);
 
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 void
-sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
+template <class _RandomAccessIterator, class _Comp>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+void __sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, _Comp& __comp) {
   _LIBCPP_DEBUG_RANDOMIZE_RANGE(__first, __last);
-  typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+  using _Comp_ref = typename __comp_ref_type<_Comp>::type;
   if (__libcpp_is_constant_evaluated()) {
-    _VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
+    std::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
   } else {
-    _VSTD::__sort<_Comp_ref>(_VSTD::__unwrap_iter(__first), _VSTD::__unwrap_iter(__last), _Comp_ref(__comp));
+    std::__sort<_Comp_ref>(std::__unwrap_iter(__first), std::__unwrap_iter(__last), _Comp_ref(__comp));
   }
 }
 
+template <class _RandomAccessIterator, class _Comp>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+void sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Comp __comp) {
+  std::__sort_impl(std::move(__first), std::move(__last), __comp);
+}
+
 template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 void sort(_RandomAccessIterator __first,
-                                                                         _RandomAccessIterator __last) {
-  _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+void sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
+  std::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
 }
 
 _LIBCPP_END_NAMESPACE_STD

libcxx/include/algorithm

@@ -53,7 +53,6 @@ namespace ranges {
     indirect_strict_weak_order<projected<iterator_t<R>, Proj>> Comp = ranges::less>
   constexpr borrowed_iterator_t<R> ranges::max_element(R&& r, Comp comp = {}, Proj proj = {});             // since C++20
 
-
   template <input_iterator I1, sentinel_for<_I1> S1, input_iterator I2, sentinel_for<_I2> S2,
           class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
     requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
@@ -283,6 +282,17 @@ namespace ranges {
     requires permutable<iterator_t<R>>
     constexpr borrowed_iterator_t<R> ranges::reverse(R&& r);                                // since C++20
 
+  template<random_access_iterator I, sentinel_for<I> S, class Comp = ranges::less,
+            class Proj = identity>
+    requires sortable<I, Comp, Proj>
+    constexpr I
+      sort(I first, S last, Comp comp = {}, Proj proj = {});                                // since C++20
+
+  template<random_access_range R, class Comp = ranges::less, class Proj = identity>
+    requires sortable<iterator_t<R>, Comp, Proj>
+    constexpr borrowed_iterator_t<R>
+      sort(R&& r, Comp comp = {}, Proj proj = {});                                          // since C++20
+
   template<class T, output_iterator<const T&> O, sentinel_for<O> S>
     constexpr O ranges::fill(O first, S last, const T& value);                              // since C++20
 
@@ -1190,6 +1200,7 @@ template <class BidirectionalIterator, class Compare>
 #include <__algorithm/ranges_replace.h>
 #include <__algorithm/ranges_replace_if.h>
 #include <__algorithm/ranges_reverse.h>
+#include <__algorithm/ranges_sort.h>
 #include <__algorithm/ranges_swap_ranges.h>
 #include <__algorithm/ranges_transform.h>
 #include <__algorithm/ranges_upper_bound.h>

libcxx/include/module.modulemap.in

@@ -284,6 +284,7 @@ module std [system] {
       module lexicographical_compare         { private header "__algorithm/lexicographical_compare.h" }
       module lower_bound                     { private header "__algorithm/lower_bound.h" }
       module make_heap                       { private header "__algorithm/make_heap.h" }
+      module make_projected                  { private header "__algorithm/make_projected.h" }
       module max                             { private header "__algorithm/max.h" }
       module max_element                     { private header "__algorithm/max_element.h" }
       module merge                           { private header "__algorithm/merge.h" }
@@ -341,6 +342,7 @@ module std [system] {
       module ranges_replace                  { private header "__algorithm/ranges_replace.h" }
       module ranges_replace_if               { private header "__algorithm/ranges_replace_if.h" }
       module ranges_reverse                  { private header "__algorithm/ranges_reverse.h" }
+      module ranges_sort                     { private header "__algorithm/ranges_sort.h" }
       module ranges_swap_ranges              { private header "__algorithm/ranges_swap_ranges.h" }
       module ranges_transform                { private header "__algorithm/ranges_transform.h" }
       module ranges_upper_bound              { private header "__algorithm/ranges_upper_bound.h" }

libcxx/src/algorithm.cpp

@@ -10,6 +10,8 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+// TODO(varconst): this currently doesn't benefit `ranges::sort` because it uses `ranges::less` instead of `__less`.
+
 template void __sort<__less<char>&, char*>(char*, char*, __less<char>&);
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 template void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&);

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_comparators.pass.cpp

@@ -207,8 +207,8 @@ constexpr bool all_the_algorithms()
     //(void)std::ranges::set_symmetric_difference(a, b, first2, Less(&copies)); assert(copies == 0);
     //(void)std::ranges::set_union(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);
     //(void)std::ranges::set_union(a, b, first2, Less(&copies)); assert(copies == 0);
-    //(void)std::ranges::sort(first, last, Less(&copies)); assert(copies == 0);
-    //(void)std::ranges::sort(a, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::sort(first, last, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::sort(a, Less(&copies)); assert(copies == 0);
     //(void)std::ranges::sort_heap(first, last, Less(&copies)); assert(copies == 0);
     //(void)std::ranges::sort_heap(a, Less(&copies)); assert(copies == 0);
     //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_partition(first, last, UnaryTrue(&copies)); assert(copies == 0); }

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_projections.pass.cpp

@@ -198,8 +198,8 @@ constexpr bool all_the_algorithms()
     //(void)std::ranges::set_symmetric_difference(a, b, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
     //(void)std::ranges::set_union(first, mid, mid, last, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
     //(void)std::ranges::set_union(a, b, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
-    //(void)std::ranges::sort(first, last, Less(), Proj(&copies)); assert(copies == 0);
-    //(void)std::ranges::sort(a, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::sort(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::sort(a, Less(), Proj(&copies)); assert(copies == 0);
     //(void)std::ranges::sort_heap(first, last, Less(), Proj(&copies)); assert(copies == 0);
     //(void)std::ranges::sort_heap(a, Less(), Proj(&copies)); assert(copies == 0);
     //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_partition(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0); }

libcxx/test/libcxx/private_headers.verify.cpp

@@ -82,6 +82,7 @@ END-SCRIPT
 #include <__algorithm/lexicographical_compare.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/lexicographical_compare.h'}}
 #include <__algorithm/lower_bound.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/lower_bound.h'}}
 #include <__algorithm/make_heap.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/make_heap.h'}}
+#include <__algorithm/make_projected.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/make_projected.h'}}
 #include <__algorithm/max.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/max.h'}}
 #include <__algorithm/max_element.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/max_element.h'}}
 #include <__algorithm/merge.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/merge.h'}}
@@ -139,6 +140,7 @@ END-SCRIPT
 #include <__algorithm/ranges_replace.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_replace.h'}}
 #include <__algorithm/ranges_replace_if.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_replace_if.h'}}
 #include <__algorithm/ranges_reverse.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_reverse.h'}}
+#include <__algorithm/ranges_sort.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_sort.h'}}
 #include <__algorithm/ranges_swap_ranges.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_swap_ranges.h'}}
 #include <__algorithm/ranges_transform.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_transform.h'}}
 #include <__algorithm/ranges_upper_bound.h> // expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_upper_bound.h'}}