Comparative Study of Path Prediction Method for Speculative Loop Execution

Execution path ratio is mostly dominated by two execution paths in program loops. We have developed Two-Path Limited Speculation Method that achieves speed-up in programs using optimization of the most frequent two paths and speculative multi-thread execution of them. The path predictor used in the method predicts the next execution path in Two-Path Limited Speculation Method, and plays an important role in performance improvement of the method. In this paper, we apply several well-known branch prediction methods to the path prediction and evaluate them in terms of mis-prediction ratio. Experimental results show that the mis-prediction ratios of the path predictors vary from 10% to 45%, depending on the benchmark programs, and are 20% on average, the Gshare path predictor performs best in eight path prediction methods.