F. C H A P T E R 2

Definitions

This chapter defines concepts unique to the SPARC64 V, the Fujitsu implementation of SPARC JPS1. For definition of terms that are common to all implementations, please refer to Chapter 2 of Commonality.

committed Term applied to an instruction when it has completed without error and all prior instructions have completed without error and have been committed. When an instruction is committed, the state of the machine is permanently changed to reflect the result of the instruction; the previously existing state is no longer needed and can be discarded.

completed Term applied to an instruction after it has finished, has sent a nonerror status to the issue unit, and all of its source operands are nonspeculative. Note: Although the state of the machine has been temporarily altered by completion of an instruction, the state has not yet been permanently changed and the old state can be recovered until the instruction has been committed.

executed Term applied to an instruction that has been processed by an execution unit such as a load unit. An instruction is in execution as long as it is still being processed by an execution unit.

fetched Term applied to an instruction that is obtained from the I2 instruction cache or from the on-chip internal cache and sent to the issue unit.

finished Term applied to an instruction when it has completed execution in a functional unit and has forwarded its result onto a result bus. Results on the result bus are transferred to the register file, as are the waiting instructions in the instruction queues.

initiated Term applied to an instruction when it has all of the resources that it needs (for example, source operands) and has been selected for execution.

instruction dispatch Synonym: instruction initiation.

instruction issued Term applied to an instruction when it has been dispatched to a reservation station.

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Fujitsu Fujitsu SPARC64 V manual Definitions, Instruction dispatch Synonym instruction initiation