Tootfinder

Taming Wild Branches: Overcoming Hard-to-Predict Branches using the Bullseye Predictor
Emet Behrendt, Shing Wai Pun, Prashant J. Nair
https://arxiv.org/abs/2506.06773

Taming Wild Branches: Overcoming Hard-to-Predict Branches using the Bullseye Predictor
Branch prediction is key to the performance of out-of-order processors. While the CBP-2016 winner TAGE-SC-L combines geometric-history tables, a statistical corrector, and a loop predictor, over half of its remaining mispredictions stem from a small set of hard-to-predict (H2P) branches. These branches occur under diverse global histories, causing repeated thrashing in TAGE and eviction before usefulness counters can mature. Prior work shows that simply enlarging the tables offers only marginal…