What is it about?

Conditional branch prediction allows the speculative fetching and execution of instructions before knowing the direction of conditional statements. As in other areas, machine learning techniques are a promising approach to building branch predictors, e.g., the Perceptron predictor. However, those traditional solutions demand large input sizes, which impose a considerable area overhead. We propose a conditional branch predictor based on the WiSARD (Wilkie, Stoneham, and Aleksander’s Recognition Device) weightless neural network model.

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Why is it important?

The WiSARD-based predictor implements one-shot online training designed to address branch prediction as a binary classification problem. We compare the WiSARD-based predictor with two state-of-the-art predictors: TAGE- SC-L (TAgged GEometric-Statistical Corrector-Loop) and the Multiperspective Perceptron. Our experimental evaluation shows that our proposed predictor, with a smaller input size, outperforms the perceptron-based predictor by about 0.09% and achieves similar accuracy to that of TAGE-SC-L. In addition, we perform an experimental sensitivity analysis to find the best predictor for each dataset, and based on these results, we designed new specialized predictors using a particular parameter composition for each dataset.


The results show that the specialized WiSARD-based predictor outperforms the state-of-the-art by more than 2.3% in the best case. Furthermore, through the implementation of specialized predictor classifiers, we discovered that utilizing 90% of the specialized predictor for a specific dataset yielded comparable performance to the corresponding specialized predictor.

Felipe França
Instituto de Telecomunicações

Read the Original

This page is a summary of: A conditional branch predictor based on weightless neural networks, Neurocomputing, October 2023, Elsevier,
DOI: 10.1016/j.neucom.2023.126637.
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