Title:
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Selective branch prediction reversal by correlating with data values and control flow
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Author:
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Aragón, Juan Luis; González, José; García Carrasco, José M.; González Colás, Antonio María
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Other authors:
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Universitat Politècnica de Catalunya. Departament d'Arquitectura de Computadors; Universitat Politècnica de Catalunya. ARCO - Microarquitectura i Compiladors |
Abstract:
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Branch prediction is one of the main hurdles in the roadmap towards deeper pipelines and higher clock frequencies. This work presents a new approach to enhancing current branch predictors: Selective Branch Prediction Reversal. The rationale behind this proposal is the fact that many branch mispredictions can be avoided if branch prediction is selectively reversed. We present a Branch Prediction Reversal Unit (BPRU) that selectively reverses branch predictions by correlating with the predicted values of the branch inputs, in addition to recent control flow. As a case study, we have included the BPRU in an already proposed branch predictor, the Branch Predictor through Value Prediction (BPVP). The effect is a reduction by half in its original misprediction rate. We have also measured the improvement when the BPRU engine is used in a hybrid scheme composed of a BPVP and a gshare predictor. Results using immediate updates show average reductions in misprediction rate ranging from 7% to 14%. Performance evaluation of the proposed BPRU in a 20-stage superscalar processor shows an IPC improvement of up to 9%. |
Abstract:
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Peer Reviewed |
Subject(s):
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-Àrees temàtiques de la UPC::Informàtica::Arquitectura de computadors -Parallel processing (Electronic computers) -Performance evaluation -Parallel architectures -Pipeline processing -Processament en paral·lel (Ordinadors) |
Rights:
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Document type:
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Article - Published version Conference Object |
Published by:
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Institute of Electrical and Electronics Engineers (IEEE)
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