[libc++] Optimize {map,set}::insert(InputIterator, InputIterator) (#154703)

philnik777 · web-flow · commit 7624c6141974 · 2025-09-03T08:15:29.000+02:00
``` ---------------------------------------------------------------------------------------------------------------------------- Benchmark old new ---------------------------------------------------------------------------------------------------------------------------- std::map<int, int>::ctor(iterator, iterator) (unsorted sequence)/0 14.2 ns 14.8 ns std::map<int, int>::ctor(iterator, iterator) (unsorted sequence)/32 519 ns 404 ns std::map<int, int>::ctor(iterator, iterator) (unsorted sequence)/1024 52460 ns 36242 ns std::map<int, int>::ctor(iterator, iterator) (unsorted sequence)/8192 724222 ns 706496 ns std::map<int, int>::ctor(iterator, iterator) (sorted sequence)/0 14.2 ns 14.7 ns std::map<int, int>::ctor(iterator, iterator) (sorted sequence)/32 429 ns 349 ns std::map<int, int>::ctor(iterator, iterator) (sorted sequence)/1024 23601 ns 14734 ns std::map<int, int>::ctor(iterator, iterator) (sorted sequence)/8192 267753 ns 112155 ns std::map<int, int>::insert(iterator, iterator) (all new keys)/0 434 ns 448 ns std::map<int, int>::insert(iterator, iterator) (all new keys)/32 950 ns 963 ns std::map<int, int>::insert(iterator, iterator) (all new keys)/1024 27205 ns 25344 ns std::map<int, int>::insert(iterator, iterator) (all new keys)/8192 294248 ns 280713 ns std::map<int, int>::insert(iterator, iterator) (half new keys)/0 435 ns 449 ns std::map<int, int>::insert(iterator, iterator) (half new keys)/32 771 ns 706 ns std::map<int, int>::insert(iterator, iterator) (half new keys)/1024 30841 ns 17495 ns std::map<int, int>::insert(iterator, iterator) (half new keys)/8192 468807 ns 285847 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from same type)/0 449 ns 453 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from same type)/32 1021 ns 932 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from same type)/1024 29796 ns 19518 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from same type)/8192 345688 ns 153966 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/0 449 ns 450 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/32 1026 ns 807 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/1024 31632 ns 15573 ns std::map<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/8192 303024 ns 128946 ns std::map<int, int>::erase(iterator, iterator) (erase half the container)/0 447 ns 452 ns std::map<int, int>::erase(iterator, iterator) (erase half the container)/32 687 ns 710 ns std::map<int, int>::erase(iterator, iterator) (erase half the container)/1024 8604 ns 8581 ns std::map<int, int>::erase(iterator, iterator) (erase half the container)/8192 65693 ns 67406 ns std::map<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/0 15.0 ns 15.0 ns std::map<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/32 2781 ns 1845 ns std::map<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/1024 187999 ns 182103 ns std::map<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/8192 2937242 ns 2934912 ns std::map<std::string, int>::ctor(iterator, iterator) (sorted sequence)/0 15.0 ns 15.2 ns std::map<std::string, int>::ctor(iterator, iterator) (sorted sequence)/32 1326 ns 2462 ns std::map<std::string, int>::ctor(iterator, iterator) (sorted sequence)/1024 81778 ns 72193 ns std::map<std::string, int>::ctor(iterator, iterator) (sorted sequence)/8192 1177292 ns 669152 ns std::map<std::string, int>::insert(iterator, iterator) (all new keys)/0 439 ns 454 ns std::map<std::string, int>::insert(iterator, iterator) (all new keys)/32 2483 ns 2465 ns std::map<std::string, int>::insert(iterator, iterator) (all new keys)/1024 187614 ns 188072 ns std::map<std::string, int>::insert(iterator, iterator) (all new keys)/8192 1654675 ns 1706603 ns std::map<std::string, int>::insert(iterator, iterator) (half new keys)/0 437 ns 452 ns std::map<std::string, int>::insert(iterator, iterator) (half new keys)/32 1836 ns 1820 ns std::map<std::string, int>::insert(iterator, iterator) (half new keys)/1024 114885 ns 121865 ns std::map<std::string, int>::insert(iterator, iterator) (half new keys)/8192 1151960 ns 1197318 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/0 438 ns 455 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/32 1599 ns 1614 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/1024 95935 ns 82159 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/8192 776480 ns 941043 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/0 435 ns 462 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/32 1723 ns 1550 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/1024 107096 ns 92850 ns std::map<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/8192 893976 ns 775046 ns std::map<std::string, int>::erase(iterator, iterator) (erase half the container)/0 436 ns 453 ns std::map<std::string, int>::erase(iterator, iterator) (erase half the container)/32 775 ns 824 ns std::map<std::string, int>::erase(iterator, iterator) (erase half the container)/1024 20241 ns 20454 ns std::map<std::string, int>::erase(iterator, iterator) (erase half the container)/8192 139038 ns 138032 ns std::set<int>::ctor(iterator, iterator) (unsorted sequence)/0 14.8 ns 14.7 ns std::set<int>::ctor(iterator, iterator) (unsorted sequence)/32 468 ns 426 ns std::set<int>::ctor(iterator, iterator) (unsorted sequence)/1024 54289 ns 39028 ns std::set<int>::ctor(iterator, iterator) (unsorted sequence)/8192 738438 ns 695720 ns std::set<int>::ctor(iterator, iterator) (sorted sequence)/0 14.7 ns 14.6 ns std::set<int>::ctor(iterator, iterator) (sorted sequence)/32 478 ns 391 ns std::set<int>::ctor(iterator, iterator) (sorted sequence)/1024 24017 ns 13905 ns std::set<int>::ctor(iterator, iterator) (sorted sequence)/8192 267862 ns 111378 ns std::set<int>::insert(iterator, iterator) (all new keys)/0 458 ns 450 ns std::set<int>::insert(iterator, iterator) (all new keys)/32 1066 ns 956 ns std::set<int>::insert(iterator, iterator) (all new keys)/1024 29190 ns 25212 ns std::set<int>::insert(iterator, iterator) (all new keys)/8192 320441 ns 279602 ns std::set<int>::insert(iterator, iterator) (half new keys)/0 454 ns 453 ns std::set<int>::insert(iterator, iterator) (half new keys)/32 816 ns 709 ns std::set<int>::insert(iterator, iterator) (half new keys)/1024 32072 ns 17074 ns std::set<int>::insert(iterator, iterator) (half new keys)/8192 403386 ns 286202 ns std::set<int>::erase(iterator, iterator) (erase half the container)/0 451 ns 452 ns std::set<int>::erase(iterator, iterator) (erase half the container)/32 710 ns 703 ns std::set<int>::erase(iterator, iterator) (erase half the container)/1024 8261 ns 8499 ns std::set<int>::erase(iterator, iterator) (erase half the container)/8192 64466 ns 67343 ns std::set<std::string>::ctor(iterator, iterator) (unsorted sequence)/0 15.2 ns 15.0 ns std::set<std::string>::ctor(iterator, iterator) (unsorted sequence)/32 3069 ns 3005 ns std::set<std::string>::ctor(iterator, iterator) (unsorted sequence)/1024 189552 ns 180933 ns std::set<std::string>::ctor(iterator, iterator) (unsorted sequence)/8192 2887579 ns 2691678 ns std::set<std::string>::ctor(iterator, iterator) (sorted sequence)/0 15.1 ns 14.9 ns std::set<std::string>::ctor(iterator, iterator) (sorted sequence)/32 2611 ns 2514 ns std::set<std::string>::ctor(iterator, iterator) (sorted sequence)/1024 91581 ns 78727 ns std::set<std::string>::ctor(iterator, iterator) (sorted sequence)/8192 1192640 ns 1158959 ns std::set<std::string>::insert(iterator, iterator) (all new keys)/0 452 ns 457 ns std::set<std::string>::insert(iterator, iterator) (all new keys)/32 2530 ns 2544 ns std::set<std::string>::insert(iterator, iterator) (all new keys)/1024 195352 ns 179614 ns std::set<std::string>::insert(iterator, iterator) (all new keys)/8192 1737890 ns 1749615 ns std::set<std::string>::insert(iterator, iterator) (half new keys)/0 451 ns 454 ns std::set<std::string>::insert(iterator, iterator) (half new keys)/32 1949 ns 1766 ns std::set<std::string>::insert(iterator, iterator) (half new keys)/1024 128853 ns 109467 ns std::set<std::string>::insert(iterator, iterator) (half new keys)/8192 1233077 ns 1177289 ns std::set<std::string>::erase(iterator, iterator) (erase half the container)/0 450 ns 451 ns std::set<std::string>::erase(iterator, iterator) (erase half the container)/32 809 ns 812 ns std::set<std::string>::erase(iterator, iterator) (erase half the container)/1024 21736 ns 21922 ns std::set<std::string>::erase(iterator, iterator) (erase half the container)/8192 135884 ns 133228 ns ``` Fixes #154650
diff --git a/libcxx/docs/ReleaseNotes/22.rst b/libcxx/docs/ReleaseNotes/22.rst
@@ -53,9 +53,10 @@ Improvements and New Features
 - The performance of ``find(key)`` in ``map``, ``set``, ``multimap`` and ``multiset`` has been improved by up to 2.3x
 - Some reallocations are now avoided in `std::filesystem::path::lexically_relative`, resulting in a performance
   improvement of up to 1.7x.
-- The performance of the ``(iterator, iterator)`` constructors of ``multimap`` and ``multiset``
+- The performance of the ``(iterator, iterator)`` constructors of ``map``, ``set``, ``multimap`` and ``multiset``
   has been improved by up to 3x
-- The performance of ``insert(iterator, iterator)`` of ``multimap`` and ``multiset`` has been improved by up to 2.5x
+- The performance of ``insert(iterator, iterator)`` of ``map``, ``set``, ``multimap`` and ``multiset`` has been improved
+  by up to 2.5x
 - The performance of ``erase(iterator, iterator)`` in the unordered containers has been improved by up to 1.9x
 - The performance of ``map::insert_or_assign`` has been improved by up to 2x
 
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
@@ -1025,6 +1025,58 @@ public:
   _LIBCPP_HIDE_FROM_ABI iterator __node_insert_multi(__node_pointer __nd);
   _LIBCPP_HIDE_FROM_ABI iterator __node_insert_multi(const_iterator __p, __node_pointer __nd);
 
+  template <class _InIter, class _Sent>
+  _LIBCPP_HIDE_FROM_ABI void __insert_range_unique(_InIter __first, _Sent __last) {
+    if (__first == __last)
+      return;
+
+    if (__root() == nullptr) {
+      __insert_node_at(
+          __end_node(), __end_node()->__left_, static_cast<__node_base_pointer>(__construct_node(*__first).release()));
+      ++__first;
+    }
+
+    auto __max_node = static_cast<__node_pointer>(std::__tree_max(static_cast<__node_base_pointer>(__root())));
+
+    using __reference = decltype(*__first);
+
+    for (; __first != __last; ++__first) {
+      std::__try_key_extraction<key_type>(
+          [this, &__max_node](const key_type& __key, __reference&& __val) {
+            if (value_comp()(__max_node->__get_value(), __key)) { // __key > __max_node
+              __node_holder __nd = __construct_node(std::forward<__reference>(__val));
+              __insert_node_at(static_cast<__end_node_pointer>(__max_node),
+                               __max_node->__right_,
+                               static_cast<__node_base_pointer>(__nd.get()));
+              __max_node = __nd.release();
+            } else {
+              __end_node_pointer __parent;
+              __node_base_pointer& __child = __find_equal(__parent, __key);
+              if (__child == nullptr) {
+                __node_holder __nd = __construct_node(std::forward<__reference>(__val));
+                __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd.release()));
+              }
+            }
+          },
+          [this, &__max_node](__reference&& __val) {
+            __node_holder __nd = __construct_node(std::forward<__reference>(__val));
+            if (value_comp()(__max_node->__get_value(), __nd->__get_value())) { // __node > __max_node
+              __insert_node_at(static_cast<__end_node_pointer>(__max_node),
+                               __max_node->__right_,
+                               static_cast<__node_base_pointer>(__nd.get()));
+              __max_node = __nd.release();
+            } else {
+              __end_node_pointer __parent;
+              __node_base_pointer& __child = __find_equal(__parent, __nd->__get_value());
+              if (__child == nullptr) {
+                __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd.release()));
+              }
+            }
+          },
+          *__first);
+    }
+  }
+
   _LIBCPP_HIDE_FROM_ABI iterator __remove_node_pointer(__node_pointer) _NOEXCEPT;
 
 #if _LIBCPP_STD_VER >= 17
diff --git a/libcxx/include/map b/libcxx/include/map
@@ -1089,18 +1089,14 @@ public:
 #  endif
 
   template <class _InputIterator>
-  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __f, _InputIterator __l) {
-    for (const_iterator __e = cend(); __f != __l; ++__f)
-      insert(__e.__i_, *__f);
+  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last) {
+    __tree_.__insert_range_unique(__first, __last);
   }
 
 #  if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<value_type> _Range>
   _LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {
-    const_iterator __end = cend();
-    for (auto&& __element : __range) {
-      insert(__end.__i_, std::forward<decltype(__element)>(__element));
-    }
+    __tree_.__insert_range_unique(ranges::begin(__range), ranges::end(__range));
   }
 #  endif
 
diff --git a/libcxx/include/set b/libcxx/include/set
@@ -742,18 +742,14 @@ public:
   }
 
   template <class _InputIterator>
-  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __f, _InputIterator __l) {
-    for (const_iterator __e = cend(); __f != __l; ++__f)
-      __tree_.__emplace_hint_unique(__e, *__f);
+  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last) {
+    __tree_.__insert_range_unique(__first, __last);
   }
 
 #  if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<value_type> _Range>
   _LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {
-    const_iterator __end = cend();
-    for (auto&& __element : __range) {
-      __tree_.__emplace_hint_unique(__end, std::forward<decltype(__element)>(__element));
-    }
+    __tree_.__insert_range_unique(ranges::begin(__range), ranges::end(__range));
   }
 #  endif
 
diff --git a/libcxx/test/std/containers/associative/map/map.modifiers/insert_iter_iter.pass.cpp b/libcxx/test/std/containers/associative/map/map.modifiers/insert_iter_iter.pass.cpp
@@ -13,64 +13,188 @@
 // template <class InputIterator>
 //   void insert(InputIterator first, InputIterator last);
 
-#include <map>
+#include <array>
 #include <cassert>
+#include <map>
 
-#include "test_macros.h"
 #include "test_iterators.h"
 #include "min_allocator.h"
 
-int main(int, char**) {
-  {
-    typedef std::map<int, double> M;
-    typedef std::pair<int, double> P;
-    P ar[] = {
-        P(1, 1),
-        P(1, 1.5),
-        P(1, 2),
-        P(2, 1),
-        P(2, 1.5),
-        P(2, 2),
-        P(3, 1),
-        P(3, 1.5),
-        P(3, 2),
-    };
-    M m;
-    m.insert(cpp17_input_iterator<P*>(ar), cpp17_input_iterator<P*>(ar + sizeof(ar) / sizeof(ar[0])));
-    assert(m.size() == 3);
-    assert(m.begin()->first == 1);
-    assert(m.begin()->second == 1);
-    assert(std::next(m.begin())->first == 2);
-    assert(std::next(m.begin())->second == 1);
-    assert(std::next(m.begin(), 2)->first == 3);
-    assert(std::next(m.begin(), 2)->second == 1);
+template <class Iter, class Alloc>
+void test_alloc() {
+  {   // Check that an empty range works correctly
+    { // Without elements in the container
+      using Map = std::map<int, int, std::less<int>, Alloc>;
+
+      std::array<std::pair<const int, int>, 0> arr;
+
+      Map map;
+      map.insert(Iter(arr.data()), Iter(arr.data() + arr.size()));
+      assert(map.size() == 0);
+      assert(map.begin() == map.end());
+    }
+    { // With 1 element in the container
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      std::array<Pair, 0> arr;
+
+      Map map;
+      map.insert(Pair(0, 0));
+      map.insert(Iter(arr.data()), Iter(arr.data() + arr.size()));
+      assert(map.size() == 1);
+      assert(*std::next(map.begin(), 0) == Pair(0, 0));
+      assert(std::next(map.begin(), 1) == map.end());
+    }
+    { // With multiple elements in the container
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      std::array<Pair, 0> arr;
+
+      Map map;
+      map.insert(Pair(0, 0));
+      map.insert(Pair(1, 1));
+      map.insert(Pair(2, 2));
+      map.insert(Iter(arr.data()), Iter(arr.data() + arr.size()));
+      assert(map.size() == 3);
+      assert(*std::next(map.begin(), 0) == Pair(0, 0));
+      assert(*std::next(map.begin(), 1) == Pair(1, 1));
+      assert(*std::next(map.begin(), 2) == Pair(2, 2));
+      assert(std::next(map.begin(), 3) == map.end());
+    }
   }
-#if TEST_STD_VER >= 11
-  {
-    typedef std::map<int, double, std::less<int>, min_allocator<std::pair<const int, double>>> M;
-    typedef std::pair<int, double> P;
-    P ar[] = {
-        P(1, 1),
-        P(1, 1.5),
-        P(1, 2),
-        P(2, 1),
-        P(2, 1.5),
-        P(2, 2),
-        P(3, 1),
-        P(3, 1.5),
-        P(3, 2),
-    };
-    M m;
-    m.insert(cpp17_input_iterator<P*>(ar), cpp17_input_iterator<P*>(ar + sizeof(ar) / sizeof(ar[0])));
-    assert(m.size() == 3);
-    assert(m.begin()->first == 1);
-    assert(m.begin()->second == 1);
-    assert(std::next(m.begin())->first == 2);
-    assert(std::next(m.begin())->second == 1);
-    assert(std::next(m.begin(), 2)->first == 3);
-    assert(std::next(m.begin(), 2)->second == 1);
+  {   // Check that 1 element is inserted correctly
+    { // Without elements in the container
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1)};
+
+      Map map;
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 1);
+      assert(*std::next(map.begin(), 0) == Pair(1, 1));
+      assert(std::next(map.begin(), 1) == map.end());
+    }
+    { // With 1 element in the container - a different key
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1)};
+
+      Map map;
+      map.insert(Pair(0, 0));
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 2);
+      assert(*std::next(map.begin(), 0) == Pair(0, 0));
+      assert(*std::next(map.begin(), 1) == Pair(1, 1));
+      assert(std::next(map.begin(), 2) == map.end());
+    }
+    { // With 1 element in the container - the same key
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1)};
+
+      Map map;
+      map.insert(Pair(1, 2));
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 1);
+      assert(*std::next(map.begin(), 0) == Pair(1, 2));
+      assert(std::next(map.begin(), 1) == map.end());
+    }
+    { // With multiple elements in the container
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1)};
+
+      Map map;
+      map.insert(Pair(0, 0));
+      map.insert(Pair(1, 1));
+      map.insert(Pair(2, 2));
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 3);
+      assert(*std::next(map.begin(), 0) == Pair(0, 0));
+      assert(*std::next(map.begin(), 1) == Pair(1, 1));
+      assert(*std::next(map.begin(), 2) == Pair(2, 2));
+      assert(std::next(map.begin(), 3) == map.end());
+    }
   }
-#endif
+  {   // Check that multiple elements are inserted correctly
+    { // Without elements in the container
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1), Pair(1, 1), Pair(3, 3)};
+
+      Map map;
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 2);
+      assert(*std::next(map.begin(), 0) == Pair(1, 1));
+      assert(*std::next(map.begin(), 1) == Pair(3, 3));
+      assert(std::next(map.begin(), 2) == map.end());
+    }
+    { // With 1 element in the container - a different key
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1), Pair(1, 1), Pair(3, 3)};
+
+      Map map;
+      map.insert(Pair(0, 0));
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 3);
+      assert(*std::next(map.begin(), 0) == Pair(0, 0));
+      assert(*std::next(map.begin(), 1) == Pair(1, 1));
+      assert(*std::next(map.begin(), 2) == Pair(3, 3));
+      assert(std::next(map.begin(), 3) == map.end());
+    }
+    { // With 1 element in the container - the same key
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1), Pair(2, 2), Pair(3, 3)};
+
+      Map map;
+      map.insert(Pair(1, 1));
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 3);
+      assert(*std::next(map.begin(), 0) == Pair(1, 1));
+      assert(*std::next(map.begin(), 1) == Pair(2, 2));
+      assert(*std::next(map.begin(), 2) == Pair(3, 3));
+      assert(std::next(map.begin(), 3) == map.end());
+    }
+    { // With multiple elements in the container
+      using Map  = std::map<int, int, std::less<int>, Alloc>;
+      using Pair = std::pair<const int, int>;
+
+      Pair arr[] = {Pair(1, 1), Pair(3, 3), Pair(4, 4)};
+
+      Map map;
+      map.insert(Pair(0, 0));
+      map.insert(Pair(1, 1));
+      map.insert(Pair(2, 2));
+      map.insert(Iter(std::begin(arr)), Iter(std::end(arr)));
+      assert(map.size() == 5);
+      assert(*std::next(map.begin(), 0) == Pair(0, 0));
+      assert(*std::next(map.begin(), 1) == Pair(1, 1));
+      assert(*std::next(map.begin(), 2) == Pair(2, 2));
+      assert(*std::next(map.begin(), 3) == Pair(3, 3));
+      assert(*std::next(map.begin(), 4) == Pair(4, 4));
+      assert(std::next(map.begin(), 5) == map.end());
+    }
+  }
+}
+
+void test() {
+  test_alloc<cpp17_input_iterator<std::pair<const int, int>*>, std::allocator<std::pair<const int, int> > >();
+  test_alloc<cpp17_input_iterator<std::pair<const int, int>*>, min_allocator<std::pair<const int, int> > >();
+}
+
+int main(int, char**) {
+  test();
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/set/insert_iter_iter.pass.cpp b/libcxx/test/std/containers/associative/set/insert_iter_iter.pass.cpp

Original file line number	Diff line number	Diff line change
`@@ -742,18 +742,14 @@ public:`
`742`	`742`	`}`
`743`	`743`
`744`	`744`	`template <class _InputIterator>`
`745`		`- _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __f, _InputIterator __l) {`
`746`		`- for (const_iterator __e = cend(); __f != __l; ++__f)`
`747`		`- __tree_.__emplace_hint_unique(__e, *__f);`
	`745`	`+ _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last) {`
	`746`	`+ __tree_.__insert_range_unique(__first, __last);`
`748`	`747`	`}`
`749`	`748`
`750`	`749`	`# if _LIBCPP_STD_VER >= 23`
`751`	`750`	`template <_ContainerCompatibleRange<value_type> _Range>`
`752`	`751`	`_LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {`
`753`		`- const_iterator __end = cend();`
`754`		`- for (auto&& __element : __range) {`
`755`		`- __tree_.__emplace_hint_unique(__end, std::forward<decltype(__element)>(__element));`
`756`		`- }`
	`752`	`+ __tree_.__insert_range_unique(ranges::begin(__range), ranges::end(__range));`
`757`	`753`	`}`
`758`	`754`	`# endif`
`759`	`755`