It was mentioned in thew video that when there is a cold load of a program there is no history to use for prediction, so branch operations just guess. Might it be possible to prime the history with an annotation in source code? I suppose this could be an innate field in a branch instruction, or a separate instruction to to inform the predictor similar to __builtin_expect. The difference from __builtin_expect being, the value would only inform a cold predictor. It seems like this might be a large benefit for initial program performance; i.e., one of the larger factors in users’ subjective performance perception.
Reply To: Prediction casten