Make gshareN_ahead slightly more accurate.#27
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The optimal global history length is a tradeoff between footprint (that is, PHT aliasing) and branch correlations. Global history footprint is a function of the global history length in branches, not in blocks. So we shift the global history by the number of branches in the block. NB: the same optimization could be applied to other gshare predictors.
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The optimal global history length is a tradeoff between footprint (that is, PHT aliasing) and branch correlations. Global history footprint is a function of the global history length in branches, not in blocks. So we shift the global history by the number of branches in the block. NB: the same optimization could be applied to other gshare predictors.