+ ;; 64-bit platforms have immediate single-floats.
+ #!+#.(cl:if (cl:= sb!vm:n-word-bits 64) '(and) '(or))
+ (make-random-descriptor (logior (ash (single-float-bits x) 32)
+ sb!vm::single-float-widetag))
+ #!-#.(cl:if (cl:= sb!vm:n-word-bits 64) '(and) '(or))