Optimize std::__tree::__assign_multi to insert the provided range at the end of the tree every time

higher-performance · higher-performance · commit 4f12629a16ca · 2025-03-12T16:55:27.000-04:00
This improves performance for the copy-assignment operators of associative containers such as std::map
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
@@ -1432,8 +1432,9 @@ void __tree<_Tp, _Compare, _Allocator>::__assign_multi(_InputIterator __first, _
       __cache.__advance();
     }
   }
+  const_iterator __e = end();
   for (; __first != __last; ++__first)
-    __insert_multi(_NodeTypes::__get_value(*__first));
+    __insert_multi(__e, _NodeTypes::__get_value(*__first));
 }
 
 template <class _Tp, class _Compare, class _Allocator>

Original file line number	Diff line number	Diff line change
`@@ -1432,8 +1432,9 @@ void __tree<_Tp, _Compare, _Allocator>::__assign_multi(_InputIterator __first, _`
`1432`	`1432`	`__cache.__advance();`
`1433`	`1433`	`}`
`1434`	`1434`	`}`
	`1435`	`+ const_iterator __e = end();`
`1435`	`1436`	`for (; __first != __last; ++__first)`
`1436`		`- __insert_multi(_NodeTypes::__get_value(*__first));`
	`1437`	`+ __insert_multi(__e, _NodeTypes::__get_value(*__first));`
`1437`	`1438`	`}`
`1438`	`1439`
`1439`	`1440`	`template <class _Tp, class _Compare, class _Allocator>`