System for rejecting and reissuing instructions after a variable delay time period

1. Field of the Present Invention A method, processor, and data processing system implementing a delayed reject mechanism are disclosed. The processor includes an issue unit suitable for issuing an instruction in a first cycle and a load store unit (LSU). The LSU includes an extend reject calculator...

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Bibliographische Detailangaben
Hauptverfasser: Le, Hung Qui, Shippy, David James
Format: Patent
Sprache:eng
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Zusammenfassung:1. Field of the Present Invention A method, processor, and data processing system implementing a delayed reject mechanism are disclosed. The processor includes an issue unit suitable for issuing an instruction in a first cycle and a load store unit (LSU). The LSU includes an extend reject calculator circuit configured to receive a set of completion information signals and generate a delay value based thereon. The LSU is adapted to determine whether to reject the instruction in a determination cycle. The number of cycles between the first cycle and the determination cycle is a function of the delay value such that reject timing is variable with respect to the first cycle. In one embodiment, the processor is further configured to reissue the instruction after the determination cycle if the instruction was rejected in the determination cycle. The delay value is conveyed via a 2-bit bus in one embodiment. The 2 bit bus permits delaying the determination cycle from 0 to 3 cycles after a finish cycle. In one embodiment, the number of cycles between the first cycle and the determination cycle includes the number of cycles required to travel a pipeline of the microprocessor plus the number of cycles indicated by the delay value.