1. In a processing system including a processor for fetching and executing a pluarlity of instructions having at least one branch instruction, and a storage from which said processor fetches the instructions, said processor comprising: means for generating control tags each of whose current value is changed when a branch instruction is executed; means connected to said generating means for appending one of said control tags to a request from a sending means before said request is sent to said storage by combining said request with said control tag; said sending means connected to said appending means for sending said request for instructions to said storage with said control tag; means connected to said storage for receiving requests with said control tags and instructions from said storage; means connected to said generating and recieving means, for determining if the control tag of the request for a received instruction is equal to the current value of the control tag in said generating means; and means connected to said determining and receiving means, for retaining each instruction received from said storage only if the control tag of the request for the received instruction is equal to the current value of the control tag in said generating means.