Natural Loops A natural loop is defined by two essential properties. 1.It must have a single-entry node,called the header. This entry node dominates all nodes in the loop,or it would not be the sole entry to the loop. 2.There must be a back edge that enters the loop header. Otherwise,it is not possible for the flow of control to return to the header directly from the "loop";i.e.,there really is no loop. CS308 Compiler Theory 11Natural Loops • A natural loop is defined by two essential properties. 1 . It must have a single-entry node, called the header. This entry node dominates all nodes in the loop, or it would not be the sole entry to the loop. 2. There must be a back edge that enters the loop header. Otherwise, it is not possible for the flow of control to return to the header directly from the "loop" ; i.e., there really is no loop. CS308 Compiler Theory 11