A New Dispatching Mechanism - Using Value Classification and Indexing - for Value Predictors

Value prediction can be used to break data dependency between instructions, ensuring simultaneous handling of multiple instructions in processors. When such instruction-level parallelism is lifted, it helps reduce a processor’s idle time and thus enhances the performance. To improve the accuracy of value prediction at low additional cost, this paper presents a new dispatching mechanism with special data value classifications and simple indexing devices. The proposed dispatching mechanism classifies data values based on their distribution patterns to attain more balanced utilization of all prediction entries. Three different value indexing devices are also introduced to set up more sophisticated and precise predicting steps. Experimental evaluation shows that the new dispatching mechanism is able to enhance the accuracy of value predictors at small extra cost.