--- a/libiberty/splay-tree.c	Thu Oct 25 07:37:49 2018 +0900
+++ b/libiberty/splay-tree.c	Thu Feb 13 11:34:05 2020 +0900
@@ -1,5 +1,5 @@
 /* A splay-tree datatype.  
-   Copyright (C) 1998-2018 Free Software Foundation, Inc.
+   Copyright (C) 1998-2020 Free Software Foundation, Inc.
    Contributed by Mark Mitchell (mark@markmitchell.com).
 
 This file is part of GNU CC.
@@ -318,7 +318,11 @@
 
 The splay tree will use @var{compare_fn} to compare nodes,
 @var{delete_key_fn} to deallocate keys, and @var{delete_value_fn} to
-deallocate values.
+deallocate values.  Keys and values will be deallocated when the
+tree is deleted using splay_tree_delete or when a node is removed
+using splay_tree_remove.  splay_tree_insert will release the previously
+inserted key and value using @var{delete_key_fn} and @var{delete_value_fn}
+if the inserted key is already found in the tree.
 
 @end deftypefn
 
@@ -372,10 +376,13 @@
 
   if (sp->root && comparison == 0)
     {
-      /* If the root of the tree already has the indicated KEY, just
-	 replace the value with VALUE.  */
+      /* If the root of the tree already has the indicated KEY, delete
+         the old key and old value, and replace them with KEY and  VALUE.  */
+      if (sp->delete_key)
+	(*sp->delete_key) (sp->root->key);
       if (sp->delete_value)
 	(*sp->delete_value)(sp->root->value);
+      sp->root->key = key;
       sp->root->value = value;
     } 
   else 
@@ -425,6 +432,8 @@
       right = sp->root->right;
 
       /* Delete the root node itself.  */
+      if (sp->delete_key)
+	(*sp->delete_key) (sp->root->key);
       if (sp->delete_value)
 	(*sp->delete_value) (sp->root->value);
       (*sp->deallocate) (sp->root, sp->allocate_data);