New primitives sxhash-eq, sxhash-eql

* doc/lispref/hash.texi (Defining Hash), etc/NEWS: Document this.
* lisp/emacs-lisp/byte-opt.el (side-effect-free-fns):
Add sxhash-equal, sxhash-eq, sxhash-eql.
* lisp/subr.el (sxhash): Now an alias for sxhash-equal.
* src/fns.c (Fsxhash_eq, Fsxhash_eql): New functions.n

1 files changed, 22 insertions, 2 deletions

diff --git a/src/fns.c b/src/fns.c
index 1ace3bb888e..da74b9cb489 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -4447,8 +4447,26 @@ sxhash (Lisp_Object obj, int depth)
                             Lisp Interface
  ***********************************************************************/
 
+DEFUN ("sxhash-eq", Fsxhash_eq, Ssxhash_eq, 1, 1, 0,
+       doc: /* Compute identity hash code for OBJ and return it as integer.
+In other words, hash codes of two non-`eq' lists will be (most likely)
+different, even if the lists contain the same elements. */)
+  (Lisp_Object obj)
+{
+  return make_number (hashfn_eq (NULL, obj));
+}
+
+DEFUN ("sxhash-eql", Fsxhash_eql, Ssxhash_eql, 1, 1, 0,
+       doc: /* Compute identity hash code for OBJ and return it as integer.
+In comparison to `sxhash-eq', it is also guaranteed that hash codes
+of equal float numbers will be the same, even if the numbers are not
+the same Lisp object. */)
+  (Lisp_Object obj)
+{
+  return make_number (hashfn_eql (NULL, obj));
+}
 
-DEFUN ("sxhash", Fsxhash, Ssxhash, 1, 1, 0,
+DEFUN ("sxhash-equal", Fsxhash_equal, Ssxhash_equal, 1, 1, 0,
        doc: /* Compute a hash code for OBJ and return it as integer.  */)
   (Lisp_Object obj)
 {
@@ -5066,7 +5084,9 @@ syms_of_fns (void)
   DEFSYM (Qkey_or_value, "key-or-value");
   DEFSYM (Qkey_and_value, "key-and-value");
 
-  defsubr (&Ssxhash);
+  defsubr (&Ssxhash_eq);
+  defsubr (&Ssxhash_eql);
+  defsubr (&Ssxhash_equal);
   defsubr (&Smake_hash_table);
   defsubr (&Scopy_hash_table);
   defsubr (&Shash_table_count);