https://github.com/philnik777 updated
https://github.com/llvm/llvm-project/pull/147681
>From 019af0059fa1d33deb0aaf278212f9a37dcbf8de Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklau...@berlin.de>
Date: Tue, 10 Jun 2025 05:56:20 +0200
Subject: [PATCH] [libc++] Add ABI flag to make __tree nodes more compact
---
libcxx/include/__configuration/abi.h | 3 +++
libcxx/include/__tree | 40 ++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/libcxx/include/__configuration/abi.h
b/libcxx/include/__configuration/abi.h
index a75cd0a675339..759687914be91 100644
--- a/libcxx/include/__configuration/abi.h
+++ b/libcxx/include/__configuration/abi.h
@@ -75,6 +75,7 @@
# define _LIBCPP_ABI_OPTIMIZED_FUNCTION
# define _LIBCPP_ABI_REGEX_CONSTANTS_NONZERO
# define _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
+# define _LIBCPP_ABI_TREE_POINTER_INT_PAIR
# define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_ARRAY
# define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_STRING_VIEW
# define _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
@@ -98,6 +99,8 @@
# endif
#endif
+#define _LIBCPP_ABI_TREE_POINTER_INT_PAIR
+
// We had some bugs where we use [[no_unique_address]] together with
construct_at,
// which causes UB as the call on construct_at could write to overlapping
subobjects
//
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
index 0f80f83e91619..ae7b348090300 100644
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -41,6 +41,7 @@
#include <__utility/forward.h>
#include <__utility/move.h>
#include <__utility/pair.h>
+#include <__utility/pointer_int_pair.h>
#include <__utility/swap.h>
#include <limits>
@@ -573,6 +574,8 @@ public:
using pointer = __rebind_pointer_t<_VoidPtr,
__tree_node_base>;
using __end_node_pointer _LIBCPP_NODEBUG = __rebind_pointer_t<_VoidPtr,
__tree_end_node<pointer> >;
+ static_assert(is_same<typename pointer_traits<_VoidPtr>::element_type,
void>::value);
+
pointer __right_;
private:
@@ -593,6 +596,43 @@ public:
__tree_node_base& operator=(__tree_node_base const&) = delete;
};
+#ifdef _LIBCPP_ABI_TREE_POINTER_INT_PAIR
+template <>
+class __tree_node_base<void*> : public
__tree_end_node<__tree_node_base<void*>*> {
+public:
+ using pointer = __tree_node_base<void*>*;
+ using __end_node_pointer _LIBCPP_NODEBUG =
__tree_end_node<__tree_node_base<void*>*>*;
+
+ pointer __right_;
+
+private:
+ using __pair_t = __pointer_int_pair<__end_node_pointer, bool,
__integer_width(1)>;
+
+ __pair_t __parent_and_color_;
+
+public:
+ _LIBCPP_HIDE_FROM_ABI pointer __parent_unsafe() const {
+ return static_cast<pointer>(__parent_and_color_.__get_ptr());
+ }
+
+ _LIBCPP_HIDE_FROM_ABI void __set_parent(pointer __ptr) {
__set_parent(static_cast<__end_node_pointer>(__ptr)); }
+
+ _LIBCPP_HIDE_FROM_ABI void __set_parent(__end_node_pointer __ptr) {
+ __parent_and_color_ = __pair_t(__ptr, __parent_and_color_.__get_value());
+ }
+
+ _LIBCPP_HIDE_FROM_ABI __end_node_pointer __get_parent() const { return
__parent_and_color_.__get_ptr(); }
+ _LIBCPP_HIDE_FROM_ABI __tree_color __get_color() const {
+ return static_cast<__tree_color>(__parent_and_color_.__get_value());
+ }
+ _LIBCPP_HIDE_FROM_ABI void __set_color(__tree_color __color) {
+ __parent_and_color_ = __pair_t(__parent_and_color_.__get_ptr(), __color ==
__tree_color::__black);
+ }
+};
+#endif // _LIBCPP_ABI_TREE_POINTER_INT_PAIR
+
+static_assert(sizeof(__tree_node_base<void*>) == 24);
+
template <class _Tp, class _VoidPtr>
class _LIBCPP_STANDALONE_DEBUG __tree_node : public __tree_node_base<_VoidPtr>
{
public:
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