Patent ID: 7805595

Claim:
A data processing apparatus, comprising: processing circuitry for performing processing operations including high priority operations and low priority operations, events occurring during performance of said processing operations; and prediction circuitry, responsive to a received event, for generating prediction data used by the processing circuitry in performing said processing operations, the prediction circuitry comprising: a history storage having a plurality of counter entries for storing count values, wherein each of the plurality of counter entries of the history storage are shared for both the high priority operations and the low priority operations; index circuitry for identifying, dependent on the received event, at least one counter entry and for causing the history storage to output a count value stored in each of said identified at least one counter entry, the prediction data being derived from the count value output from the history storage; update control circuitry, responsive to update data generated by the processing circuitry during performance of said processing operations, for modifying at least one of said count values stored in the history storage, the update control circuitry having a priority dependent modification mechanism such that the modification to the at least one of said count values is dependent on a priority of the processing operation with which that update data is associated, the priority dependent modification mechanism being such that the prediction data output for a received event associated with a high priority operation is more accurate than the prediction data output for a received event associated with a low priority operation, wherein the update control circuitry is responsive to the update data to determine whether the at least one of said count values should be incremented or decremented, and the priority dependent modification mechanism specifies an amount by which the at least one of said count values is to be incremented or decremented, the priority dependent modification mechanism specifying said amount to be larger for update data associated with a high priority operation than for update data associated with a low priority operation.