Abstract:

In most current high-performance microprocessors, the predicted target addresses of procedure returns are provided by a return-address stack （RAS）.   In order to achieve higher prediction accuracy, it is necessary to repair the return-address-stack after branch mispredictions. First, three kinds of re  turn-address stack repair mechanisms used widely are analyzed, a novel retura-address stack repair technique called backup stack is proposed, and its im plementation is detailed. At last, the backup stack repair mechanism is compared with other three ones and a conclusion is drawn. With the backup stack  technique used to repair the return-address stack, a 100% retura-address prediction accuracy can be achieved unless overflow appears.

Key words: return-address stack, return-address stack repair mechanism, backup stack, branch prediction