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Merged
merged 1 commit into from
Aug 22, 2025
Merged

[libc++] Optimize multi{map,set}::insert(InputIterator, InputIterator) #152691

merged 1 commit into from
Aug 22, 2025

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@philnik777 philnik777 commented Aug 8, 2025 •
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---------------------------------------------------------------------------------------------------------------------------------
Benchmark                                                                                                      old            new
---------------------------------------------------------------------------------------------------------------------------------
std::multimap<int, int>::ctor(iterator, iterator) (unsorted sequence)/0                                    15.0 ns        14.9 ns
std::multimap<int, int>::ctor(iterator, iterator) (unsorted sequence)/32                                    499 ns         453 ns
std::multimap<int, int>::ctor(iterator, iterator) (unsorted sequence)/1024                                48042 ns       45413 ns
std::multimap<int, int>::ctor(iterator, iterator) (unsorted sequence)/8192                               720794 ns      699102 ns
std::multimap<int, int>::ctor(iterator, iterator) (sorted sequence)/0                                      14.9 ns        15.0 ns
std::multimap<int, int>::ctor(iterator, iterator) (sorted sequence)/32                                      469 ns         312 ns
std::multimap<int, int>::ctor(iterator, iterator) (sorted sequence)/1024                                  24870 ns       12535 ns
std::multimap<int, int>::ctor(iterator, iterator) (sorted sequence)/8192                                 320474 ns       98615 ns
std::multimap<int, int>::insert(iterator, iterator) (all new keys)/0                                        455 ns         462 ns
std::multimap<int, int>::insert(iterator, iterator) (all new keys)/32                                      1069 ns        1024 ns
std::multimap<int, int>::insert(iterator, iterator) (all new keys)/1024                                   29448 ns       29650 ns
std::multimap<int, int>::insert(iterator, iterator) (all new keys)/8192                                  316087 ns      307652 ns
std::multimap<int, int>::insert(iterator, iterator) (half new keys)/0                                       456 ns         459 ns
std::multimap<int, int>::insert(iterator, iterator) (half new keys)/32                                      982 ns         926 ns
std::multimap<int, int>::insert(iterator, iterator) (half new keys)/1024                                  40963 ns       35205 ns
std::multimap<int, int>::insert(iterator, iterator) (half new keys)/8192                                 470584 ns      411297 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from same type)/0                     455 ns         455 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from same type)/32                    981 ns         908 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from same type)/1024                29573 ns       18495 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from same type)/8192               373138 ns      145490 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/0                      456 ns         457 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/32                    1001 ns         846 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/1024                 28886 ns       16380 ns
std::multimap<int, int>::insert(iterator, iterator) (product_iterator from zip_view)/8192                296621 ns      129634 ns
std::multimap<int, int>::erase(iterator, iterator) (erase half the container)/0                             461 ns         459 ns
std::multimap<int, int>::erase(iterator, iterator) (erase half the container)/32                            712 ns         721 ns
std::multimap<int, int>::erase(iterator, iterator) (erase half the container)/1024                         8683 ns        9032 ns
std::multimap<int, int>::erase(iterator, iterator) (erase half the container)/8192                        67316 ns       70256 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/0                            15.0 ns        17.0 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/32                           3133 ns        3079 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/1024                       189504 ns      190940 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (unsorted sequence)/8192                      2578482 ns     2534645 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (sorted sequence)/0                              15.2 ns        16.9 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (sorted sequence)/32                             2690 ns        2189 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (sorted sequence)/1024                          98889 ns       71348 ns
std::multimap<std::string, int>::ctor(iterator, iterator) (sorted sequence)/8192                        1274108 ns     1159230 ns
std::multimap<std::string, int>::insert(iterator, iterator) (all new keys)/0                                455 ns         456 ns
std::multimap<std::string, int>::insert(iterator, iterator) (all new keys)/32                              2007 ns        2076 ns
std::multimap<std::string, int>::insert(iterator, iterator) (all new keys)/1024                          160027 ns      156791 ns
std::multimap<std::string, int>::insert(iterator, iterator) (all new keys)/8192                         1540491 ns     1470501 ns
std::multimap<std::string, int>::insert(iterator, iterator) (half new keys)/0                               455 ns         457 ns
std::multimap<std::string, int>::insert(iterator, iterator) (half new keys)/32                             2003 ns        2063 ns
std::multimap<std::string, int>::insert(iterator, iterator) (half new keys)/1024                         163551 ns      167734 ns
std::multimap<std::string, int>::insert(iterator, iterator) (half new keys)/8192                        1592041 ns     1519982 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/0             452 ns         451 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/32           1647 ns        1553 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/1024       115961 ns       82969 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from same type)/8192       805502 ns      809357 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/0              456 ns         461 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/32            1599 ns        1569 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/1024        105381 ns       83137 ns
std::multimap<std::string, int>::insert(iterator, iterator) (product_iterator from zip_view)/8192        769359 ns      627449 ns
std::multimap<std::string, int>::erase(iterator, iterator) (erase half the container)/0                     454 ns         459 ns
std::multimap<std::string, int>::erase(iterator, iterator) (erase half the container)/32                    831 ns         826 ns
std::multimap<std::string, int>::erase(iterator, iterator) (erase half the container)/1024                22997 ns       22864 ns
std::multimap<std::string, int>::erase(iterator, iterator) (erase half the container)/8192               138008 ns      137066 ns
std::multiset<int>::ctor(iterator, iterator) (unsorted sequence)/0                                         15.0 ns        14.7 ns
std::multiset<int>::ctor(iterator, iterator) (unsorted sequence)/32                                         529 ns         425 ns
std::multiset<int>::ctor(iterator, iterator) (unsorted sequence)/1024                                     49784 ns       42171 ns
std::multiset<int>::ctor(iterator, iterator) (unsorted sequence)/8192                                    725039 ns      699864 ns
std::multiset<int>::ctor(iterator, iterator) (sorted sequence)/0                                           14.9 ns        14.8 ns
std::multiset<int>::ctor(iterator, iterator) (sorted sequence)/32                                           513 ns         354 ns
std::multiset<int>::ctor(iterator, iterator) (sorted sequence)/1024                                       25201 ns       12103 ns
std::multiset<int>::ctor(iterator, iterator) (sorted sequence)/8192                                      320001 ns       96768 ns
std::multiset<int>::insert(iterator, iterator) (all new keys)/0                                             452 ns         458 ns
std::multiset<int>::insert(iterator, iterator) (all new keys)/32                                           1048 ns        1026 ns
std::multiset<int>::insert(iterator, iterator) (all new keys)/1024                                        29217 ns       29509 ns
std::multiset<int>::insert(iterator, iterator) (all new keys)/8192                                       310906 ns      309259 ns
std::multiset<int>::insert(iterator, iterator) (half new keys)/0                                            462 ns         454 ns
std::multiset<int>::insert(iterator, iterator) (half new keys)/32                                           988 ns         908 ns
std::multiset<int>::insert(iterator, iterator) (half new keys)/1024                                       41545 ns       32431 ns
std::multiset<int>::insert(iterator, iterator) (half new keys)/8192                                      470042 ns      409618 ns
std::multiset<int>::erase(iterator, iterator) (erase half the container)/0                                  453 ns         453 ns
std::multiset<int>::erase(iterator, iterator) (erase half the container)/32                                 725 ns         717 ns
std::multiset<int>::erase(iterator, iterator) (erase half the container)/1024                              8734 ns        8848 ns
std::multiset<int>::erase(iterator, iterator) (erase half the container)/8192                             70278 ns       68465 ns
std::multiset<std::string>::ctor(iterator, iterator) (unsorted sequence)/0                                 15.4 ns        16.5 ns
std::multiset<std::string>::ctor(iterator, iterator) (unsorted sequence)/32                                3060 ns        1894 ns
std::multiset<std::string>::ctor(iterator, iterator) (unsorted sequence)/1024                            185144 ns      180302 ns
std::multiset<std::string>::ctor(iterator, iterator) (unsorted sequence)/8192                           2780124 ns     1883800 ns
std::multiset<std::string>::ctor(iterator, iterator) (sorted sequence)/0                                   15.6 ns        16.8 ns
std::multiset<std::string>::ctor(iterator, iterator) (sorted sequence)/32                                  2694 ns        2395 ns
std::multiset<std::string>::ctor(iterator, iterator) (sorted sequence)/1024                               85031 ns       80462 ns
std::multiset<std::string>::ctor(iterator, iterator) (sorted sequence)/8192                              854175 ns     1122345 ns
std::multiset<std::string>::insert(iterator, iterator) (all new keys)/0                                     459 ns         457 ns
std::multiset<std::string>::insert(iterator, iterator) (all new keys)/32                                   2120 ns        1999 ns
std::multiset<std::string>::insert(iterator, iterator) (all new keys)/1024                               161187 ns      141931 ns
std::multiset<std::string>::insert(iterator, iterator) (all new keys)/8192                              1416852 ns     1343619 ns
std::multiset<std::string>::insert(iterator, iterator) (half new keys)/0                                    459 ns         455 ns
std::multiset<std::string>::insert(iterator, iterator) (half new keys)/32                                  2022 ns        1927 ns
std::multiset<std::string>::insert(iterator, iterator) (half new keys)/1024                              169273 ns      152779 ns
std::multiset<std::string>::insert(iterator, iterator) (half new keys)/8192                             1640003 ns     1489332 ns
std::multiset<std::string>::erase(iterator, iterator) (erase half the container)/0                          453 ns         452 ns
std::multiset<std::string>::erase(iterator, iterator) (erase half the container)/32                         827 ns         806 ns
std::multiset<std::string>::erase(iterator, iterator) (erase half the container)/1024                     20004 ns       20002 ns
std::multiset<std::string>::erase(iterator, iterator) (erase half the container)/8192                    135073 ns      134105 ns

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github-actions bot commented Aug 8, 2025 •
edited
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✅ With the latest revision this PR passed the C/C++ code formatter.

@philnik777 philnik777 changed the title [libc++] Optimize multi{map,set}::insert [libc++] Optimize multi{map,set}::insert(InputIterator, InputIterator) Aug 11, 2025
@philnik777 philnik777 force-pushed the optimize_tree_insert_range_multi branch 2 times, most recently from 2f03769 to 8bed2d3 Compare August 11, 2025 09:41
ldionne
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@ldionne ldionne marked this pull request as ready for review August 12, 2025 15:05
@ldionne ldionne requested a review from a team as a code owner August 12, 2025 15:05
@llvmbot llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Aug 12, 2025
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llvmbot commented Aug 12, 2025

@llvm/pr-subscribers-libcxx

Author: Nikolas Klauser (philnik777)

Changes 
--------------------------------------------------------------------------------------------------------------------
Benchmark                                                                                        old             new
--------------------------------------------------------------------------------------------------------------------
std::multiset&lt;int&gt;::ctor(iterator, iterator) (unsorted sequence)/0                           14.8 ns         16.0 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (unsorted sequence)/32                           513 ns          536 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (unsorted sequence)/1024                       50523 ns        49099 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (unsorted sequence)/8192                      712956 ns       773317 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (sorted sequence)/0                             14.6 ns         16.0 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (sorted sequence)/32                             505 ns          404 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (sorted sequence)/1024                         24907 ns        14673 ns
std::multiset&lt;int&gt;::ctor(iterator, iterator) (sorted sequence)/8192                        317355 ns       115852 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (all new keys)/0                               449 ns          458 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (all new keys)/32                             1036 ns          965 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (all new keys)/1024                          29504 ns        20190 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (all new keys)/8192                         313616 ns       150854 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (half new keys)/0                              456 ns          459 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (half new keys)/32                            1013 ns          971 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (half new keys)/1024                         41227 ns        24008 ns
std::multiset&lt;int&gt;::insert(iterator, iterator) (half new keys)/8192                        478994 ns       343475 ns
std::multiset&lt;int&gt;::erase(iterator, iterator) (erase half the container)/0                    459 ns          456 ns
std::multiset&lt;int&gt;::erase(iterator, iterator) (erase half the container)/32                   732 ns          720 ns
std::multiset&lt;int&gt;::erase(iterator, iterator) (erase half the container)/1024               10027 ns         8581 ns
std::multiset&lt;int&gt;::erase(iterator, iterator) (erase half the container)/8192               74175 ns        65850 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (unsorted sequence)/0                   15.2 ns         17.1 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (unsorted sequence)/32                  3093 ns         3015 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (unsorted sequence)/1024              164606 ns       178851 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (unsorted sequence)/8192             2239105 ns      2458905 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (sorted sequence)/0                     15.1 ns         16.9 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (sorted sequence)/32                    1293 ns         2497 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (sorted sequence)/1024                 94936 ns        68618 ns
std::multiset&lt;std::string&gt;::ctor(iterator, iterator) (sorted sequence)/8192               1252379 ns      1136337 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (all new keys)/0                       456 ns          463 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (all new keys)/32                     2024 ns         1807 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (all new keys)/1024                 159767 ns       105691 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (all new keys)/8192                1424748 ns       762697 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (half new keys)/0                      461 ns          458 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (half new keys)/32                    2013 ns         2040 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (half new keys)/1024                166583 ns       141373 ns
std::multiset&lt;std::string&gt;::insert(iterator, iterator) (half new keys)/8192               1566078 ns      1358940 ns
std::multiset&lt;std::string&gt;::erase(iterator, iterator) (erase half the container)/0            454 ns          454 ns
std::multiset&lt;std::string&gt;::erase(iterator, iterator) (erase half the container)/32           841 ns          813 ns
std::multiset&lt;std::string&gt;::erase(iterator, iterator) (erase half the container)/1024       18878 ns        20836 ns
std::multiset&lt;std::string&gt;::erase(iterator, iterator) (erase half the container)/8192      136735 ns       135926 ns

Full diff: https://github.com/llvm/llvm-project/pull/152691.diff

3 Files Affected:

  • (modified) libcxx/include/__tree (+30)
  • (modified) libcxx/include/map (+1)
  • (modified) libcxx/include/set (+4-7)
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
index 6dadd0915c984..5baadca719ac4 100644
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -970,6 +970,36 @@ public:
     __emplace_hint_multi(__p, std::move(__value));
   }
 
+  template <class _InIter, class _Sent>
+  _LIBCPP_HIDE_FROM_ABI void __insert_range_multi(_InIter __first, _Sent __last) {
+    if (__first == __last)
+      return;
+
+    if (__root() == nullptr) { // Make sure we always have a root node
+      __node_holder __node = __construct_node(*__first);
+      __insert_node_at(__end_node(), __end_node()->__left_, static_cast<__node_base_pointer>(__node.release()));
+      ++__first;
+    }
+
+    auto __max_node = static_cast<__node_pointer>(std::__tree_max(static_cast<__node_base_pointer>(__root())));
+    __node_pointer __last_insertion = __root();
+
+    for (; __first != __last; ++__first) {
+      __node_holder __node = __construct_node(*__first);
+      if (!value_comp()(__node->__get_value(), __max_node->__get_value())) { // __node >= __max_val
+        __insert_node_at(static_cast<__end_node_pointer>(__max_node),
+                         __max_node->__right_,
+                         static_cast<__node_base_pointer>(__node.get()));
+        __max_node = __node.release();
+      } else {
+        __end_node_pointer __parent;
+        __node_base_pointer& __child = __find_leaf(++iterator(__last_insertion), __parent, __node->__value_);
+        __last_insertion             = __node.get();
+        __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__node.release()));
+      }
+    }
+  }
+
   _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> __node_assign_unique(const value_type& __v, __node_pointer __dest);
 
   _LIBCPP_HIDE_FROM_ABI iterator __node_insert_multi(__node_pointer __nd);
diff --git a/libcxx/include/map b/libcxx/include/map
index 9f98abef9afe0..a84b5592244fa 100644
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -593,6 +593,7 @@ erase_if(multimap<Key, T, Compare, Allocator>& c, Predicate pred);  // C++20
 #  include <__memory/unique_ptr.h>
 #  include <__memory_resource/polymorphic_allocator.h>
 #  include <__node_handle>
+#  include <__ranges/access.h>
 #  include <__ranges/concepts.h>
 #  include <__ranges/container_compatible_range.h>
 #  include <__ranges/from_range.h>
diff --git a/libcxx/include/set b/libcxx/include/set
index c77345bc5dc1f..18488b56e7dd2 100644
--- a/libcxx/include/set
+++ b/libcxx/include/set
@@ -530,6 +530,7 @@ erase_if(multiset<Key, Compare, Allocator>& c, Predicate pred);  // C++20
 #  include <__memory/allocator_traits.h>
 #  include <__memory_resource/polymorphic_allocator.h>
 #  include <__node_handle>
+#  include <__ranges/access.h>
 #  include <__ranges/concepts.h>
 #  include <__ranges/container_compatible_range.h>
 #  include <__ranges/from_range.h>
@@ -1205,18 +1206,14 @@ 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_multi(__e, *__f);
+  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last) {
+    __tree_.__insert_range_multi(__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_multi(__end, std::forward<decltype(__element)>(__element));
-    }
+    __tree_.__insert_range_multi(ranges::begin(__range), ranges::end(__range));
   }
 #  endif

@ldionne ldionne mentioned this pull request Aug 13, 2025
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@philnik777 philnik777 force-pushed the optimize_tree_insert_range_multi branch 3 times, most recently from 0e5d4f1 to 691222a Compare August 15, 2025 08:19
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ldionne approved these changes Aug 19, 2025
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LGTM

ldionne
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It seems like we forgot to look at the existing tests. The current coverage is very basic. Let's add at least:

  • Inserting an empty range
  • Inserting a range with 1 element (existing AND non-existing)
  • Inserting a range with no existing elements
  • Inserting a range with existing elements
  • Inserting a range with sorted and non-sorted elements

Requesting changes until we have that.

ldionne
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More test cases:

  • Inserting into an empty / non-empty / 1-element multimap

@philnik777 philnik777 force-pushed the optimize_tree_insert_range_multi branch 3 times, most recently from 21c073a to dd319b1 Compare August 20, 2025 13:35
@ldionne ldionne mentioned this pull request Aug 20, 2025
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@philnik777 philnik777 force-pushed the optimize_tree_insert_range_multi branch from dd319b1 to e890a85 Compare August 21, 2025 07:48
@ldionne ldionne merged commit 1c7f140 into llvm:main Aug 22, 2025
75 of 79 checks passed
@philnik777 philnik777 deleted the optimize_tree_insert_range_multi branch August 25, 2025 07:08
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