Fast and accurate branch predictor simulation

International audienceThe complexity of embedded processors has raised dramatically, due to the addition of architectural add-ons which improve performances significantly. High level models used in system simulation usually ignore these additions as the major issue is functional correctness. However, accurate estimates of software execution is sometimes required, therefore we focus in this paper on one of theses architectural features, the branch predictor. Unfortunately, advanced branch predictors use large tables, so that models directly implementing these schemes slow down simulation dramatically. To limit the simulation overhead, we define a modeling approach that we demonstrate on a state of the art predictor. We implemented the model in a dynamic binary translation based instruction set simulator and measured an accuracy of prediction of about 95% for a run-time overhead of less than 5%