[libc++] Optimize __tree copy/move constructor/assignment with allocator

Author: philnik777

libcxx/include/__tree

@@ -899,6 +899,18 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI __tree(const __tree& __t);
+
+  _LIBCPP_HIDE_FROM_ABI __tree(const __tree& __other, const allocator_type& __alloc)
+      : __begin_node_(__end_node()), __node_alloc_(__alloc), __size_(0), __value_comp_(__other.value_comp()) {
+    if (__other.size() == 0)
+      return;
+
+    *__root_ptr()       = static_cast<__node_base_pointer>(__copy_construct_tree(__other.__root()));
+    __root()->__parent_ = __end_node();
+    __begin_node_       = static_cast<__end_node_pointer>(std::__tree_min(__end_node()->__left_));
+    __size_             = __other.size();
+  }
+
   _LIBCPP_HIDE_FROM_ABI __tree& operator=(const __tree& __t);
   template <class _ForwardIterator>
   _LIBCPP_HIDE_FROM_ABI void __assign_unique(_ForwardIterator __first, _ForwardIterator __last);
@@ -1007,27 +1019,6 @@ public:
         std::forward<_Args>(__args)...);
   }
 
-  template <class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI void
-  __insert_unique_from_orphaned_node(const_iterator __p, __get_node_value_type_t<_Tp>&& __value) {
-    __emplace_hint_unique(__p, const_cast<key_type&&>(__value.first), std::move(__value.second));
-  }
-
-  template <class _ValueT = _Tp, __enable_if_t<!__is_tree_value_type_v<_ValueT>, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI void __insert_unique_from_orphaned_node(const_iterator __p, _Tp&& __value) {
-    __emplace_hint_unique(__p, std::move(__value));
-  }
-
-  template <class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI void __insert_multi_from_orphaned_node(const_iterator __p, value_type&& __value) {
-    __emplace_hint_multi(__p, const_cast<key_type&&>(__value.first), std::move(__value.second));
-  }
-
-  template <class _ValueT = _Tp, __enable_if_t<!__is_tree_value_type_v<_ValueT>, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI void __insert_multi_from_orphaned_node(const_iterator __p, _Tp&& __value) {
-    __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)
@@ -1400,19 +1391,20 @@ private:
   // copy the exact structure 1:1. Since this is for copy construction _only_ we know that we get a correct tree. If we
   // didn't get a correct tree, the invariants of __tree are broken and we have a much bigger problem than an improperly
   // balanced tree.
+  template <class _NodeConstructor>
 #ifdef _LIBCPP_COMPILER_CLANG_BASED // FIXME: GCC complains about not being able to always_inline a recursive function
   _LIBCPP_HIDE_FROM_ABI
 #endif
   __node_pointer
-  __copy_construct_tree(__node_pointer __src) {
+  __construct_from_tree(__node_pointer __src, _NodeConstructor __construct) {
     if (!__src)
       return nullptr;
 
-    __node_holder __new_node = __construct_node(__src->__get_value());
+    __node_holder __new_node = __construct(__src->__get_value());
 
     unique_ptr<__node, __tree_deleter> __left(
-        __copy_construct_tree(static_cast<__node_pointer>(__src->__left_)), __node_alloc_);
-    __node_pointer __right = __copy_construct_tree(static_cast<__node_pointer>(__src->__right_));
+        __construct_from_tree(static_cast<__node_pointer>(__src->__left_), __construct), __node_alloc_);
+    __node_pointer __right = __construct_from_tree(static_cast<__node_pointer>(__src->__right_), __construct);
 
     __node_pointer __new_node_ptr = __new_node.release();
 
@@ -1426,46 +1418,85 @@ private:
     return __new_node_ptr;
   }
 
+  _LIBCPP_HIDE_FROM_ABI __node_pointer __copy_construct_tree(__node_pointer __src) {
+    return __construct_from_tree(__src, [this](const value_type& __val) { return __construct_node(__val); });
+  }
+
+  template <class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
+  _LIBCPP_HIDE_FROM_ABI __node_pointer __move_construct_tree(__node_pointer __src) {
+    return __construct_from_tree(__src, [this](value_type& __val) {
+      return __construct_node(const_cast<key_type&&>(__val.first), std::move(__val.second));
+    });
+  }
+
+  template <class _ValueT = _Tp, __enable_if_t<!__is_tree_value_type_v<_ValueT>, int> = 0>
+  _LIBCPP_HIDE_FROM_ABI __node_pointer __move_construct_tree(__node_pointer __src) {
+    return __construct_from_tree(__src, [this](value_type& __val) { return __construct_node(std::move(__val)); });
+  }
+
+  template <class _Assignment, class _ConstructionAlg>
   // This copy assignment will always produce a correct red-black-tree assuming the incoming tree is correct, since our
   // own tree is a red-black-tree and the incoming tree is a red-black-tree. The invariants of a red-black-tree are
   // temporarily not met until all of the incoming red-black tree is copied.
 #ifdef _LIBCPP_COMPILER_CLANG_BASED // FIXME: GCC complains about not being able to always_inline a recursive function
   _LIBCPP_HIDE_FROM_ABI
 #endif
-  __node_pointer
-  __copy_assign_tree(__node_pointer __dest, __node_pointer __src) {
+  __node_pointer __assign_from_tree(
+      __node_pointer __dest, __node_pointer __src, _Assignment __assign, _ConstructionAlg __continue_with_construct) {
     if (!__src) {
       destroy(__dest);
       return nullptr;
     }
 
-    __assign_value(__dest->__get_value(), __src->__get_value());
+    __assign(__dest->__get_value(), __src->__get_value());
     __dest->__is_black_ = __src->__is_black_;
 
     // If we already have a left node in the destination tree, reuse it and copy-assign recursively
     if (__dest->__left_) {
-      __dest->__left_ = static_cast<__node_base_pointer>(__copy_assign_tree(
-          static_cast<__node_pointer>(__dest->__left_), static_cast<__node_pointer>(__src->__left_)));
+      __dest->__left_ = static_cast<__node_base_pointer>(__assign_from_tree(
+          static_cast<__node_pointer>(__dest->__left_),
+          static_cast<__node_pointer>(__src->__left_),
+          __assign,
+          __continue_with_construct));
 
       // Otherwise, we must create new nodes; copy-construct from here on
     } else if (__src->__left_) {
-      auto __new_left       = __copy_construct_tree(static_cast<__node_pointer>(__src->__left_));
+      auto __new_left       = __continue_with_construct(static_cast<__node_pointer>(__src->__left_));
       __dest->__left_       = static_cast<__node_base_pointer>(__new_left);
       __new_left->__parent_ = static_cast<__end_node_pointer>(__dest);
     }
 
     // Identical to the left case above, just for the right nodes
     if (__dest->__right_) {
-      __dest->__right_ = static_cast<__node_base_pointer>(__copy_assign_tree(
-          static_cast<__node_pointer>(__dest->__right_), static_cast<__node_pointer>(__src->__right_)));
+      __dest->__right_ = static_cast<__node_base_pointer>(__assign_from_tree(
+          static_cast<__node_pointer>(__dest->__right_),
+          static_cast<__node_pointer>(__src->__right_),
+          __assign,
+          __continue_with_construct));
     } else if (__src->__right_) {
-      auto __new_right       = __copy_construct_tree(static_cast<__node_pointer>(__src->__right_));
+      auto __new_right       = __continue_with_construct(static_cast<__node_pointer>(__src->__right_));
       __dest->__right_       = static_cast<__node_base_pointer>(__new_right);
       __new_right->__parent_ = static_cast<__end_node_pointer>(__dest);
     }
 
     return __dest;
   }
+
+  _LIBCPP_HIDE_FROM_ABI __node_pointer __copy_assign_tree(__node_pointer __dest, __node_pointer __src) {
+    return __assign_from_tree(
+        __dest,
+        __src,
+        [](value_type& __lhs, const value_type& __rhs) { __assign_value(__lhs, std::move(__rhs)); },
+        [this](__node_pointer __nd) { return __copy_construct_tree(__nd); });
+  }
+
+  _LIBCPP_HIDE_FROM_ABI __node_pointer __move_assign_tree(__node_pointer __dest, __node_pointer __src) {
+    return __assign_from_tree(
+        __dest,
+        __src,
+        [](value_type& __lhs, value_type& __rhs) { __assign_value(__lhs, std::move(__rhs)); },
+        [this](__node_pointer __nd) { return __move_construct_tree(__nd); });
+  }
 };
 
 // Precondition:  __size_ != 0
@@ -1606,21 +1637,26 @@ __tree<_Tp, _Compare, _Allocator>::__tree(__tree&& __t) _NOEXCEPT_(
 
 template <class _Tp, class _Compare, class _Allocator>
 __tree<_Tp, _Compare, _Allocator>::__tree(__tree&& __t, const allocator_type& __a)
-    : __node_alloc_(__node_allocator(__a)), __size_(0), __value_comp_(std::move(__t.value_comp())) {
+    : __begin_node_(__end_node()),
+      __node_alloc_(__node_allocator(__a)),
+      __size_(0),
+      __value_comp_(std::move(__t.value_comp())) {
+  if (__t.size() == 0)
+    return;
   if (__a == __t.__alloc()) {
-    if (__t.__size_ == 0)
-      __begin_node_ = __end_node();
-    else {
-      __begin_node_                    = __t.__begin_node_;
-      __end_node()->__left_            = __t.__end_node()->__left_;
-      __end_node()->__left_->__parent_ = static_cast<__end_node_pointer>(__end_node());
-      __size_                          = __t.__size_;
-      __t.__begin_node_                = __t.__end_node();
-      __t.__end_node()->__left_        = nullptr;
-      __t.__size_                      = 0;
-    }
+    __begin_node_                    = __t.__begin_node_;
+    __end_node()->__left_            = __t.__end_node()->__left_;
+    __end_node()->__left_->__parent_ = static_cast<__end_node_pointer>(__end_node());
+    __size_                          = __t.__size_;
+    __t.__begin_node_                = __t.__end_node();
+    __t.__end_node()->__left_        = nullptr;
+    __t.__size_                      = 0;
   } else {
-    __begin_node_ = __end_node();
+    *__root_ptr()       = static_cast<__node_base_pointer>(__move_construct_tree(__t.__root()));
+    __root()->__parent_ = __end_node();
+    __begin_node_       = static_cast<__end_node_pointer>(std::__tree_min(__end_node()->__left_));
+    __size_             = __t.size();
+    __t.clear(); // Ensure that __t is in a valid state after moving out the keys
   }
 }
 
@@ -1645,22 +1681,21 @@ void __tree<_Tp, _Compare, _Allocator>::__move_assign(__tree& __t, true_type)
 
 template <class _Tp, class _Compare, class _Allocator>
 void __tree<_Tp, _Compare, _Allocator>::__move_assign(__tree& __t, false_type) {
-  if (__node_alloc() == __t.__node_alloc())
+  if (__node_alloc() == __t.__node_alloc()) {
     __move_assign(__t, true_type());
-  else {
-    value_comp()       = std::move(__t.value_comp());
-    const_iterator __e = end();
+  } else {
+    value_comp() = std::move(__t.value_comp());
     if (__size_ != 0) {
-      _DetachedTreeCache __cache(this);
-      while (__cache.__get() != nullptr && __t.__size_ != 0) {
-        __assign_value(__cache.__get()->__get_value(), std::move(__t.remove(__t.begin())->__get_value()));
-        __node_insert_multi(__cache.__get());
-        __cache.__advance();
-      }
-    }
-    while (__t.__size_ != 0) {
-      __insert_multi_from_orphaned_node(__e, std::move(__t.remove(__t.begin())->__get_value()));
+      *__root_ptr() = static_cast<__node_base_pointer>(__move_assign_tree(__root(), __t.__root()));
+    } else {
+      *__root_ptr() = static_cast<__node_base_pointer>(__move_construct_tree(__t.__root()));
+      if (__root())
+        __root()->__parent_ = __end_node();
     }
+    __begin_node_ =
+        __end_node()->__left_ ? static_cast<__end_node_pointer>(std::__tree_min(__end_node()->__left_)) : __end_node();
+    __size_ = __t.size();
+    __t.clear(); // Ensure that __t is in a valid state after moving out the keys
   }
 }
 

libcxx/include/map

@@ -997,7 +997,7 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI map(map&& __m) = default;
 
-  _LIBCPP_HIDE_FROM_ABI map(map&& __m, const allocator_type& __a);
+  _LIBCPP_HIDE_FROM_ABI map(map&& __m, const allocator_type& __a) : __tree_(std::move(__m.__tree_), __a) {}
 
   _LIBCPP_HIDE_FROM_ABI map& operator=(map&& __m) = default;
 
@@ -1025,10 +1025,7 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI explicit map(const allocator_type& __a) : __tree_(typename __base::allocator_type(__a)) {}
 
-  _LIBCPP_HIDE_FROM_ABI map(const map& __m, const allocator_type& __a)
-      : __tree_(__m.__tree_.value_comp(), typename __base::allocator_type(__a)) {
-    insert(__m.begin(), __m.end());
-  }
+  _LIBCPP_HIDE_FROM_ABI map(const map& __m, const allocator_type& __alloc) : __tree_(__m.__tree_, __alloc) {}
 
   _LIBCPP_HIDE_FROM_ABI ~map() { static_assert(sizeof(std::__diagnose_non_const_comparator<_Key, _Compare>()), ""); }
 
@@ -1428,18 +1425,6 @@ map(initializer_list<pair<_Key, _Tp>>, _Allocator)
 #  endif
 
 #  ifndef _LIBCPP_CXX03_LANG
-template <class _Key, class _Tp, class _Compare, class _Allocator>
-map<_Key, _Tp, _Compare, _Allocator>::map(map&& __m, const allocator_type& __a)
-    : __tree_(std::move(__m.__tree_), typename __base::allocator_type(__a)) {
-  if (__a != __m.get_allocator()) {
-    const_iterator __e = cend();
-    while (!__m.empty()) {
-      __tree_.__insert_unique_from_orphaned_node(
-          __e.__i_, std::move(__m.__tree_.remove(__m.begin().__i_)->__get_value()));
-    }
-  }
-}
-
 template <class _Key, class _Tp, class _Compare, class _Allocator>
 _Tp& map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k) {
   return __tree_.__emplace_unique(std::piecewise_construct, std::forward_as_tuple(__k), std::forward_as_tuple())
@@ -1685,7 +1670,7 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI multimap(multimap&& __m) = default;
 
-  _LIBCPP_HIDE_FROM_ABI multimap(multimap&& __m, const allocator_type& __a);
+  _LIBCPP_HIDE_FROM_ABI multimap(multimap&& __m, const allocator_type& __a) : __tree_(std::move(__m.__tree_), __a) {}
 
   _LIBCPP_HIDE_FROM_ABI multimap& operator=(multimap&& __m) = default;
 
@@ -1714,10 +1699,7 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI explicit multimap(const allocator_type& __a) : __tree_(typename __base::allocator_type(__a)) {}
 
-  _LIBCPP_HIDE_FROM_ABI multimap(const multimap& __m, const allocator_type& __a)
-      : __tree_(__m.__tree_.value_comp(), typename __base::allocator_type(__a)) {
-    insert(__m.begin(), __m.end());
-  }
+  _LIBCPP_HIDE_FROM_ABI multimap(const multimap& __m, const allocator_type& __a) : __tree_(__m.__tree_, __a) {}
 
   _LIBCPP_HIDE_FROM_ABI ~multimap() {
     static_assert(sizeof(std::__diagnose_non_const_comparator<_Key, _Compare>()), "");
@@ -1992,19 +1974,6 @@ multimap(initializer_list<pair<_Key, _Tp>>, _Allocator)
     -> multimap<remove_const_t<_Key>, _Tp, less<remove_const_t<_Key>>, _Allocator>;
 #  endif
 
-#  ifndef _LIBCPP_CXX03_LANG
-template <class _Key, class _Tp, class _Compare, class _Allocator>
-multimap<_Key, _Tp, _Compare, _Allocator>::multimap(multimap&& __m, const allocator_type& __a)
-    : __tree_(std::move(__m.__tree_), typename __base::allocator_type(__a)) {
-  if (__a != __m.get_allocator()) {
-    const_iterator __e = cend();
-    while (!__m.empty())
-      __tree_.__insert_multi_from_orphaned_node(
-          __e.__i_, std::move(__m.__tree_.remove(__m.begin().__i_)->__get_value()));
-  }
-}
-#  endif
-
 template <class _Key, class _Tp, class _Compare, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool
 operator==(const multimap<_Key, _Tp, _Compare, _Allocator>& __x, const multimap<_Key, _Tp, _Compare, _Allocator>& __y) {

libcxx/include/set

@@ -673,12 +673,10 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI explicit set(const allocator_type& __a) : __tree_(__a) {}
 
-  _LIBCPP_HIDE_FROM_ABI set(const set& __s, const allocator_type& __a) : __tree_(__s.__tree_.value_comp(), __a) {
-    insert(__s.begin(), __s.end());
-  }
+  _LIBCPP_HIDE_FROM_ABI set(const set& __s, const allocator_type& __alloc) : __tree_(__s.__tree_, __alloc) {}
 
 #  ifndef _LIBCPP_CXX03_LANG
-  _LIBCPP_HIDE_FROM_ABI set(set&& __s, const allocator_type& __a);
+  _LIBCPP_HIDE_FROM_ABI set(set&& __s, const allocator_type& __alloc) : __tree_(std::move(__s.__tree_), __alloc) {}
 
   _LIBCPP_HIDE_FROM_ABI set(initializer_list<value_type> __il, const value_compare& __comp = value_compare())
       : __tree_(__comp) {
@@ -948,19 +946,6 @@ template <class _Key, class _Allocator, class = enable_if_t<__is_allocator_v<_Al
 set(initializer_list<_Key>, _Allocator) -> set<_Key, less<_Key>, _Allocator>;
 #  endif
 
-#  ifndef _LIBCPP_CXX03_LANG
-
-template <class _Key, class _Compare, class _Allocator>
-set<_Key, _Compare, _Allocator>::set(set&& __s, const allocator_type& __a) : __tree_(std::move(__s.__tree_), __a) {
-  if (__a != __s.get_allocator()) {
-    const_iterator __e = cend();
-    while (!__s.empty())
-      insert(__e, std::move(__s.__tree_.remove(__s.begin())->__get_value()));
-  }
-}
-
-#  endif // _LIBCPP_CXX03_LANG
-
 template <class _Key, class _Compare, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool
 operator==(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
@@ -1130,13 +1115,10 @@ public:
 #  ifndef _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI multiset(multiset&& __s) = default;
 
-  _LIBCPP_HIDE_FROM_ABI multiset(multiset&& __s, const allocator_type& __a);
+  _LIBCPP_HIDE_FROM_ABI multiset(multiset&& __s, const allocator_type& __a) : __tree_(std::move(__s.__tree_), __a) {}
 #  endif // _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI explicit multiset(const allocator_type& __a) : __tree_(__a) {}
-  _LIBCPP_HIDE_FROM_ABI multiset(const multiset& __s, const allocator_type& __a)
-      : __tree_(__s.__tree_.value_comp(), __a) {
-    insert(__s.begin(), __s.end());
-  }
+  _LIBCPP_HIDE_FROM_ABI multiset(const multiset& __s, const allocator_type& __a) : __tree_(__s.__tree_, __a) {}
 
 #  ifndef _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI multiset(initializer_list<value_type> __il, const value_compare& __comp = value_compare())
@@ -1409,20 +1391,6 @@ template <class _Key, class _Allocator, class = enable_if_t<__is_allocator_v<_Al
 multiset(initializer_list<_Key>, _Allocator) -> multiset<_Key, less<_Key>, _Allocator>;
 #  endif
 
-#  ifndef _LIBCPP_CXX03_LANG
-
-template <class _Key, class _Compare, class _Allocator>
-multiset<_Key, _Compare, _Allocator>::multiset(multiset&& __s, const allocator_type& __a)
-    : __tree_(std::move(__s.__tree_), __a) {
-  if (__a != __s.get_allocator()) {
-    const_iterator __e = cend();
-    while (!__s.empty())
-      insert(__e, std::move(__s.__tree_.remove(__s.begin())->__get_value()));
-  }
-}
-
-#  endif // _LIBCPP_CXX03_LANG
-
 template <class _Key, class _Compare, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI bool
 operator==(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {