[libcxx-commits] [libcxx] [libc++] Optimize {set, map}::{lower, upper}_bound (PR #161366)

[Louis Dionne via libcxx-commits]

================
@@ -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) {
----------------
ldionne wrote:

Let's do some cleanup as part of this patch. Let's rename this to `__lower_bound_multi` and do something similar for `upper_bound`. We basically shouldn't have members named `upper_bound` and `lower_bound` (public names) in `__tree` after this patch.

https://github.com/llvm/llvm-project/pull/161366