cl-return-from is an autoloaded Lisp macro in `cl-macs.el'.

(cl-return-from NAME &optional RESULT)

Return from the block named NAME.
This jumps out to the innermost enclosing `(cl-block NAME ...)' form,
returning RESULT from that form (or nil if RESULT is omitted).
This is compatible with Common Lisp, but note that `defun' and
`defmacro' do not create implicit blocks as they do in Common Lisp.