| 摘要 |
A method and apparatus for handling branch instructions contained within a source program includes applying a set of heuristics to classify each of the branch instructions in the source program as either a hard-to-predict type or a simple type of branch. A system implements a multi-heuristic branch predictor (21) comprising a large, relatively simple branch predictor (23) having many entries, to accommodate the majority of branch instructions encountered in a program, and a second, relatively small, sophisticated branch predictor (24) having a few entries. The sophisticated branch predictor (24) predicts the target addresses of the hard-to-predict branches. By mapping hard-to-predict branches to the sophisticated branch predictor (24), and easy-to-predict branches to the relatively simple branch predictor (23), overall performance is enhanced.
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