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[libc++] Optimize __tree::find and __tree::__erase_unique #152370

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merged 1 commit into from
Aug 15, 2025
Merged

[libc++] Optimize __tree::find and __tree::__erase_unique #152370

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2 changes: 2 additions & 0 deletions libcxx/docs/ReleaseNotes/22.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,8 @@ Improvements and New Features
- The performance of ``map::operator=(const map&)`` has been improved by up to 11x
- The performance of ``unordered_set::unordered_set(const unordered_set&)`` has been improved by up to 3.3x.
- The performance of ``unordered_set::operator=(const unordered_set&)`` has been improved by up to 5x.
- The performance of ``map::erase`` and ``set::erase`` has been improved by up to 2x
- The performance of ``find(key)`` in ``map``, ``set``, ``multimap`` and ``multiset`` has been improved by up to 2.3x

Deprecations and Removals
-------------------------
Expand Down
36 changes: 15 additions & 21 deletions libcxx/include/__tree
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Original file line number Diff line number Diff line change
Expand Up @@ -1038,9 +1038,22 @@ public:
__insert_node_at(__end_node_pointer __parent, __node_base_pointer& __child, __node_base_pointer __new_node) _NOEXCEPT;

template <class _Key>
_LIBCPP_HIDE_FROM_ABI iterator find(const _Key& __v);
_LIBCPP_HIDE_FROM_ABI iterator find(const _Key& __key) {
__end_node_pointer __parent;
__node_base_pointer __match = __find_equal(__parent, __key);
if (__match == nullptr)
return end();
return iterator(static_cast<__node_pointer>(__match));
}

template <class _Key>
_LIBCPP_HIDE_FROM_ABI const_iterator find(const _Key& __v) const;
_LIBCPP_HIDE_FROM_ABI const_iterator find(const _Key& __key) const {
__end_node_pointer __parent;
__node_base_pointer __match = __find_equal(__parent, __key);
if (__match == nullptr)
return end();
return const_iterator(static_cast<__node_pointer>(__match));
}

template <class _Key>
_LIBCPP_HIDE_FROM_ABI size_type __count_unique(const _Key& __k) const;
Expand Down Expand Up @@ -2060,25 +2073,6 @@ __tree<_Tp, _Compare, _Allocator>::__erase_multi(const _Key& __k) {
return __r;
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::iterator __tree<_Tp, _Compare, _Allocator>::find(const _Key& __v) {
iterator __p = __lower_bound(__v, __root(), __end_node());
if (__p != end() && !value_comp()(__v, *__p))
return __p;
return end();
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::const_iterator
__tree<_Tp, _Compare, _Allocator>::find(const _Key& __v) const {
const_iterator __p = __lower_bound(__v, __root(), __end_node());
if (__p != end() && !value_comp()(__v, *__p))
return __p;
return end();
}

template <class _Tp, class _Compare, class _Allocator>
template <class _Key>
typename __tree<_Tp, _Compare, _Allocator>::size_type
Expand Down
51 changes: 30 additions & 21 deletions libcxx/test/std/containers/associative/multimap/multimap.ops/find.pass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,15 @@
#include "private_constructor.h"
#include "is_transparent.h"

template <class Iter>
bool iter_in_range(Iter first, Iter last, Iter to_find) {
for (; first != last; ++first) {
if (first == to_find)
return true;
}
return false;
}

int main(int, char**) {
typedef std::pair<const int, double> V;
{
Expand All @@ -30,15 +39,15 @@ int main(int, char**) {
V ar[] = {V(5, 1), V(5, 2), V(5, 3), V(7, 1), V(7, 2), V(7, 3), V(9, 1), V(9, 2), V(9, 3)};
M m(ar, ar + sizeof(ar) / sizeof(ar[0]));
R r = m.find(5);
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(6);
assert(r == m.end());
r = m.find(7);
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(8);
assert(r == m.end());
r = m.find(9);
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(10);
assert(r == m.end());
}
Expand All @@ -47,15 +56,15 @@ int main(int, char**) {
V ar[] = {V(5, 1), V(5, 2), V(5, 3), V(7, 1), V(7, 2), V(7, 3), V(9, 1), V(9, 2), V(9, 3)};
const M m(ar, ar + sizeof(ar) / sizeof(ar[0]));
R r = m.find(5);
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(6);
assert(r == m.end());
r = m.find(7);
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(8);
assert(r == m.end());
r = m.find(9);
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(10);
assert(r == m.end());
}
Expand All @@ -68,15 +77,15 @@ int main(int, char**) {
V ar[] = {V(5, 1), V(5, 2), V(5, 3), V(7, 1), V(7, 2), V(7, 3), V(9, 1), V(9, 2), V(9, 3)};
M m(ar, ar + sizeof(ar) / sizeof(ar[0]));
R r = m.find(5);
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(6);
assert(r == m.end());
r = m.find(7);
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(8);
assert(r == m.end());
r = m.find(9);
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(10);
assert(r == m.end());
}
Expand All @@ -85,15 +94,15 @@ int main(int, char**) {
V ar[] = {V(5, 1), V(5, 2), V(5, 3), V(7, 1), V(7, 2), V(7, 3), V(9, 1), V(9, 2), V(9, 3)};
const M m(ar, ar + sizeof(ar) / sizeof(ar[0]));
R r = m.find(5);
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(6);
assert(r == m.end());
r = m.find(7);
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(8);
assert(r == m.end());
r = m.find(9);
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(10);
assert(r == m.end());
}
Expand All @@ -107,28 +116,28 @@ int main(int, char**) {
V ar[] = {V(5, 1), V(5, 2), V(5, 3), V(7, 1), V(7, 2), V(7, 3), V(9, 1), V(9, 2), V(9, 3)};
M m(ar, ar + sizeof(ar) / sizeof(ar[0]));
R r = m.find(5);
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(6);
assert(r == m.end());
r = m.find(7);
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(8);
assert(r == m.end());
r = m.find(9);
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(10);
assert(r == m.end());

r = m.find(C2Int(5));
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(C2Int(6));
assert(r == m.end());
r = m.find(C2Int(7));
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(C2Int(8));
assert(r == m.end());
r = m.find(C2Int(9));
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(C2Int(10));
assert(r == m.end());
}
Expand All @@ -150,15 +159,15 @@ int main(int, char**) {
m.insert(std::make_pair<PC, double>(PC::make(9), 3));

R r = m.find(5);
assert(r == m.begin());
assert(iter_in_range(std::next(m.begin(), 0), std::next(m.begin(), 3), r));
r = m.find(6);
assert(r == m.end());
r = m.find(7);
assert(r == std::next(m.begin(), 3));
assert(iter_in_range(std::next(m.begin(), 3), std::next(m.begin(), 6), r));
r = m.find(8);
assert(r == m.end());
r = m.find(9);
assert(r == std::next(m.begin(), 6));
assert(iter_in_range(std::next(m.begin(), 6), std::next(m.begin(), 9), r));
r = m.find(10);
assert(r == m.end());
}
Expand Down
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