[libcxx-commits] [libcxx] [libc++] Optimize {set, map}::{lower, upper}_bound (PR #161366)
via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Oct 1 08:24:55 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libcxx
Author: Nikolas Klauser (philnik777)
<details>
<summary>Changes</summary>
Apple M4:
```
Benchmark Baseline Candidate Difference % Difference
--------------------------------------------------------------------------------------------- ---------- ----------- ------------ --------------
std::map<int,_int>::lower_bound(key)_(existent)/0 0.01 0.01 -0.00 -25.78
std::map<int,_int>::lower_bound(key)_(existent)/1024 7.94 4.28 -3.66 -46.09
std::map<int,_int>::lower_bound(key)_(existent)/32 2.73 1.69 -1.03 -37.89
std::map<int,_int>::lower_bound(key)_(existent)/8192 11.63 5.52 -6.11 -52.55
std::map<int,_int>::lower_bound(key)_(non-existent)/0 0.28 0.28 -0.00 -1.35
std::map<int,_int>::lower_bound(key)_(non-existent)/1024 17.21 7.63 -9.58 -55.67
std::map<int,_int>::lower_bound(key)_(non-existent)/32 4.71 3.26 -1.45 -30.71
std::map<int,_int>::lower_bound(key)_(non-existent)/8192 26.82 10.58 -16.24 -60.55
std::map<int,_int>::upper_bound(key)_(existent)/0 0.01 0.01 0.00 20.62
std::map<int,_int>::upper_bound(key)_(existent)/1024 7.93 3.61 -4.32 -54.49
std::map<int,_int>::upper_bound(key)_(existent)/32 2.83 1.98 -0.85 -30.01
std::map<int,_int>::upper_bound(key)_(existent)/8192 11.69 5.72 -5.97 -51.06
std::map<int,_int>::upper_bound(key)_(non-existent)/0 0.28 0.28 -0.00 -1.36
std::map<int,_int>::upper_bound(key)_(non-existent)/1024 17.21 8.00 -9.21 -53.53
std::map<int,_int>::upper_bound(key)_(non-existent)/32 4.70 2.93 -1.78 -37.76
std::map<int,_int>::upper_bound(key)_(non-existent)/8192 26.54 11.18 -15.36 -57.89
std::map<std::string,_int>::lower_bound(key)_(existent)/0 0.04 0.04 -0.00 -3.26
std::map<std::string,_int>::lower_bound(key)_(existent)/1024 27.46 26.25 -1.22 -4.43
std::map<std::string,_int>::lower_bound(key)_(existent)/32 19.17 15.71 -3.46 -18.07
std::map<std::string,_int>::lower_bound(key)_(existent)/8192 35.33 35.03 -0.30 -0.84
std::map<std::string,_int>::lower_bound(key)_(non-existent)/0 0.27 0.27 -0.00 -1.45
std::map<std::string,_int>::lower_bound(key)_(non-existent)/1024 24.88 24.17 -0.70 -2.83
std::map<std::string,_int>::lower_bound(key)_(non-existent)/32 11.67 11.63 -0.04 -0.32
std::map<std::string,_int>::lower_bound(key)_(non-existent)/8192 31.81 32.33 0.52 1.64
std::map<std::string,_int>::upper_bound(key)_(existent)/0 0.04 0.04 -0.00 -2.22
std::map<std::string,_int>::upper_bound(key)_(existent)/1024 29.91 26.51 -3.40 -11.38
std::map<std::string,_int>::upper_bound(key)_(existent)/32 19.69 17.74 -1.95 -9.92
std::map<std::string,_int>::upper_bound(key)_(existent)/8192 32.55 35.24 2.69 8.25
std::map<std::string,_int>::upper_bound(key)_(non-existent)/0 0.27 0.27 -0.00 -1.74
std::map<std::string,_int>::upper_bound(key)_(non-existent)/1024 23.87 26.77 2.91 12.18
std::map<std::string,_int>::upper_bound(key)_(non-existent)/32 11.44 11.81 0.37 3.24
std::map<std::string,_int>::upper_bound(key)_(non-existent)/8192 33.02 32.59 -0.43 -1.29
std::set<int>::lower_bound(key)_(existent)/0 0.01 0.01 0.00 0.48
std::set<int>::lower_bound(key)_(existent)/1024 7.83 4.21 -3.62 -46.23
std::set<int>::lower_bound(key)_(existent)/32 2.74 1.68 -1.06 -38.81
std::set<int>::lower_bound(key)_(existent)/8192 22.75 11.12 -11.63 -51.12
std::set<int>::lower_bound(key)_(non-existent)/0 0.28 0.27 -0.01 -3.52
std::set<int>::lower_bound(key)_(non-existent)/1024 17.15 8.40 -8.75 -51.03
std::set<int>::lower_bound(key)_(non-existent)/32 4.63 2.50 -2.13 -46.03
std::set<int>::lower_bound(key)_(non-existent)/8192 28.88 11.05 -17.82 -61.72
std::set<int>::upper_bound(key)_(existent)/0 0.01 0.01 -0.00 -7.79
std::set<int>::upper_bound(key)_(existent)/1024 7.80 3.63 -4.16 -53.42
std::set<int>::upper_bound(key)_(existent)/32 2.81 1.90 -0.91 -32.44
std::set<int>::upper_bound(key)_(existent)/8192 21.93 11.35 -10.58 -48.26
std::set<int>::upper_bound(key)_(non-existent)/0 0.28 0.27 -0.01 -3.81
std::set<int>::upper_bound(key)_(non-existent)/1024 16.76 7.38 -9.38 -55.98
std::set<int>::upper_bound(key)_(non-existent)/32 4.58 3.10 -1.48 -32.31
std::set<int>::upper_bound(key)_(non-existent)/8192 26.95 10.70 -16.25 -60.29
std::set<std::string>::lower_bound(key)_(existent)/0 0.04 0.04 0.00 0.02
std::set<std::string>::lower_bound(key)_(existent)/1024 28.08 27.04 -1.04 -3.71
std::set<std::string>::lower_bound(key)_(existent)/32 17.53 16.94 -0.58 -3.34
std::set<std::string>::lower_bound(key)_(existent)/8192 32.79 33.28 0.49 1.49
std::set<std::string>::lower_bound(key)_(non-existent)/0 0.28 0.28 -0.00 -0.06
std::set<std::string>::lower_bound(key)_(non-existent)/1024 25.23 24.38 -0.85 -3.38
std::set<std::string>::lower_bound(key)_(non-existent)/32 11.45 11.68 0.24 2.07
std::set<std::string>::lower_bound(key)_(non-existent)/8192 32.30 36.80 4.50 13.95
std::set<std::string>::upper_bound(key)_(existent)/0 0.04 0.04 -0.00 -0.14
std::set<std::string>::upper_bound(key)_(existent)/1024 26.71 26.37 -0.34 -1.27
std::set<std::string>::upper_bound(key)_(existent)/32 20.07 19.06 -1.02 -5.06
std::set<std::string>::upper_bound(key)_(existent)/8192 36.69 35.50 -1.19 -3.25
std::set<std::string>::upper_bound(key)_(non-existent)/0 0.28 0.28 -0.00 -0.16
std::set<std::string>::upper_bound(key)_(non-existent)/1024 24.48 24.90 0.42 1.73
std::set<std::string>::upper_bound(key)_(non-existent)/32 11.68 11.77 0.09 0.77
std::set<std::string>::upper_bound(key)_(non-existent)/8192 33.16 34.12 0.96 2.89
```
---
Full diff: https://github.com/llvm/llvm-project/pull/161366.diff
3 Files Affected:
- (modified) libcxx/include/__tree (+42)
- (modified) libcxx/include/map (+7-3)
- (modified) libcxx/include/set (+8-4)
``````````diff
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
index 61c910c52c536..ef53bf1fa8364 100644
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -1165,6 +1165,48 @@ public:
template <class _Key>
_LIBCPP_HIDE_FROM_ABI size_type __count_multi(const _Key& __k) const;
+ template <bool _LowerBound, class _Key>
+ _LIBCPP_HIDE_FROM_ABI __end_node_pointer __lower_upper_bound_unique_impl(const _Key& __v) const {
+ auto __rt = __root();
+ auto __result = __end_node();
+ auto __comp = __lazy_synth_three_way_comparator<_Compare, _Key, value_type>(value_comp());
+ while (__rt != nullptr) {
+ auto __comp_res = __comp(__v, __rt->__get_value());
+
+ if (__comp_res.__less()) {
+ __result = static_cast<__end_node_pointer>(__rt);
+ __rt = static_cast<__node_pointer>(__rt->__left_);
+ } else if (__comp_res.__greater()) {
+ __rt = static_cast<__node_pointer>(__rt->__right_);
+ } else if _LIBCPP_CONSTEXPR (_LowerBound) {
+ return static_cast<__end_node_pointer>(__rt);
+ } else {
+ return __rt->__right_ ? static_cast<__end_node_pointer>(std::__tree_min(__rt->__right_)) : __result;
+ }
+ }
+ return __result;
+ }
+
+ template <class _Key>
+ _LIBCPP_HIDE_FROM_ABI iterator __lower_bound_unique(const _Key& __v) {
+ return iterator(__lower_upper_bound_unique_impl<true>(__v));
+ }
+
+ template <class _Key>
+ _LIBCPP_HIDE_FROM_ABI const_iterator __lower_bound_unique(const _Key& __v) const {
+ return const_iterator(__lower_upper_bound_unique_impl<true>(__v));
+ }
+
+ template <class _Key>
+ _LIBCPP_HIDE_FROM_ABI iterator __upper_bound_unique(const _Key& __v) {
+ return iterator(__lower_upper_bound_unique_impl<false>(__v));
+ }
+
+ template <class _Key>
+ _LIBCPP_HIDE_FROM_ABI const_iterator __upper_bound_unique(const _Key& __v) const {
+ return iterator(__lower_upper_bound_unique_impl<false>(__v));
+ }
+
template <class _Key>
_LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _Key& __v) {
return __lower_bound(__v, __root(), __end_node());
diff --git a/libcxx/include/map b/libcxx/include/map
index a63dfec910aae..58840556d42f5 100644
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -1269,7 +1269,9 @@ public:
# endif // _LIBCPP_STD_VER >= 20
_LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { return __tree_.lower_bound(__k); }
- _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const { return __tree_.lower_bound(__k); }
+ _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const {
+ return __tree_.__lower_bound_unique(__k);
+ }
# if _LIBCPP_STD_VER >= 14
template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
_LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _K2& __k) {
@@ -1282,8 +1284,10 @@ public:
}
# endif
- _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.upper_bound(__k); }
- _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const { return __tree_.upper_bound(__k); }
+ _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.__upper_bound_unique(__k); }
+ _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const {
+ return __tree_.__upper_bound_unique(__k);
+ }
# if _LIBCPP_STD_VER >= 14
template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
_LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _K2& __k) {
diff --git a/libcxx/include/set b/libcxx/include/set
index 75529e7bac6ff..f77dc4821e997 100644
--- a/libcxx/include/set
+++ b/libcxx/include/set
@@ -849,8 +849,10 @@ public:
}
# endif // _LIBCPP_STD_VER >= 20
- _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { return __tree_.lower_bound(__k); }
- _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const { return __tree_.lower_bound(__k); }
+ _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { return __tree_.__lower_bound_unique(__k); }
+ _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const {
+ return __tree_.__lower_bound_unique(__k);
+ }
# if _LIBCPP_STD_VER >= 14
template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
_LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _K2& __k) {
@@ -863,8 +865,10 @@ public:
}
# endif
- _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.upper_bound(__k); }
- _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const { return __tree_.upper_bound(__k); }
+ _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.__upper_bound_unique(__k); }
+ _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const {
+ return __tree_.__upper_bound_unique(__k);
+ }
# if _LIBCPP_STD_VER >= 14
template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
_LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _K2& __k) {
``````````
</details>
https://github.com/llvm/llvm-project/pull/161366
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