1. An execution slice circuit for use within a processor core, the execution slice circuit comprising: a master execution slice having a first reservation station for receiving instructions of a first instruction stream and first portions of instructions of the first instruction stream that have a greater execution width than an execution width of the master execution slice; a slave execution slice having a second reservation station for receiving instructions of a second instruction stream and second portions of instructions of the first instruction stream that have the greater execution width, wherein the master execution slice further includes a queue position array for storing indices to entries in the second reservation station of the slave execution slice that correspond to the second portions of the instructions of the first instruction stream that require the greater execution width; and a control logic circuit that detects when a first instruction of the first instruction stream has the greater width and controls the slave execution slice to reserve a first issue cycle for issuing the first instruction in parallel across the master execution slice and the slave execution slice, by storing the first portions of the instructions of the first instruction stream in the first reservation station of the master execution slice, storing the second portions of the instructions of the first instruction stream in the second reservation station of the slave execution slice, and storing the indices to the entries in the second reservation station corresponding to the second portions of the instructions of the first instruction stream that require the greater execution width, wherein the slave execution slice further includes an override circuit to override an index provided by the slave execution slice to the second reservation station with one of the indices stored in the queue position array of the master execution slice when an instruction of the first instruction stream having the greater execution width is issued.