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BTreeMap: reuse BoxedNode instances directly instead of their contents #77408

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BTreeMap: reuse BoxedNode instances directly instead of their contents #77408

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10 changes: 3 additions & 7 deletions library/alloc/src/collections/btree/node.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -128,10 +128,6 @@ impl<K, V> BoxedNode<K, V> {
BoxedNode { ptr: Unique::from(&mut Box::leak(node).data) }
}

unsafe fn from_ptr(ptr: NonNull<LeafNode<K, V>>) -> Self {
BoxedNode { ptr: unsafe { Unique::new_unchecked(ptr.as_ptr()) } }
}

fn as_ptr(&self) -> NonNull<LeafNode<K, V>> {
NonNull::from(self.ptr)
}
Expand Down Expand Up @@ -199,7 +195,7 @@ impl<K, V> Root<K, V> {
/// and is the opposite of `pop_internal_level`.
pub fn push_internal_level(&mut self) -> NodeRef<marker::Mut<'_>, K, V, marker::Internal> {
let mut new_node = Box::new(unsafe { InternalNode::new() });
new_node.edges[0].write(unsafe { BoxedNode::from_ptr(self.node.as_ptr()) });
new_node.edges[0].write(unsafe { ptr::read(&mut self.node) });

self.node = BoxedNode::from_internal(new_node);
self.height += 1;
Expand All @@ -225,8 +221,8 @@ impl<K, V> Root<K, V> {

let top = self.node.ptr;

let internal_node = unsafe { self.internal_node_as_mut() };
self.node = unsafe { BoxedNode::from_ptr(internal_node.first_edge().descend().node) };
let mut internal_node = unsafe { self.internal_node_as_mut() };
self.node = unsafe { internal_node.as_internal_mut().edges[0].assume_init_read() };
self.height -= 1;
self.node_as_mut().as_leaf_mut().parent = None;

Expand Down