DYNAMICALLY ENABLED BRANCH PREDICTION

摘要

Embodiments for a processor that selectively enables and disables branch prediction are disclosed. The processor may include counters to track a number of fetched instructions, a number of branches, and a number of mispredicted branches. A misprediction threshold may be calculated dependent upon the tracked number of branches and a predefined misprediction ratio. Branch prediction may then be disabled when the number of mispredictions exceed the determined threshold value and dependent upon the branch rate.

主权项

1. An processor, comprising:
a fetch unit configured to speculatively fetch instructions of a predicted branch responsive to a determination that a branch prediction mode has been enabled; a control circuit configured to:
determine, responsive to a determination that a predetermined number of instructions have been fetched, a branch rate value indicative of a number of branch instructions included in the predetermined number of instructions;determine a branch misprediction rate value indicative of a number of mispredicted branch instructions included in the number of branch instructions;enable the branch prediction mode responsive to a determination that the branch misprediction rate value is less than or equal to a first threshold value; anddisable the branch prediction mode responsive to a determination that the branch misprediction rate value is greater than the first threshold value and a determination that the branch rate value is less than a second threshold value.