TRACKING SPECULATIVE EXECUTION OF INSTRUCTIONS FOR A REGISTER RENAMING DATA STORE

摘要

First processing circuitry processes at least part of a stream of program instructions. The first processing circuitry has registers for storing data and register renaming circuitry for mapping architectural register specifiers to physical register specifiers. A renaming data store stores renaming entries for identifying a register mapping between the architectural and physical register specifiers. At least some renaming entries have a count value indicating a number of speculation points occurring between generation of a previous count value and generation of the count value. The speculation points may for example be branch operation or load/store operations.

主权项

1. A data processing apparatus for processing a stream of program instructions, comprising first processing circuitry configured to process at least some of the program instructions, the first processing circuitry comprising:
a plurality of registers for storing data; register renaming circuitry configured to map architectural register specifiers identified by the program instructions to physical register specifiers identifying the plurality of registers; and a renaming data store configured to store a plurality of renaming entries, each renaming entry for identifying a register mapping between at least one of the architectural register specifiers and at least one of the physical register specifiers; wherein: at least some renaming entries have a corresponding count value, the count value indicating a number of speculation points occurring between generation of a previous count value and generation of the count value; a speculation point comprising a point of program flow of the stream of program instructions following which at least one program instruction is executed speculatively by the data processing apparatus before it is known whether the at least one program instruction should have been executed following the speculation point; and the count value comprises an N-bit value, where N is an integer and N>1.