Method and apparatus for generating branch predictions for multiple branch instructions indexed by a single instruction pointer

摘要

A method and apparatus for generating respective branch predictions for first and second branch instructions, both indexed by a first instruction pointer, is disclosed. The apparatus includes dynamic branch prediction circuitry for generating a branch prediction based on the outcome of previous branch resolution activity, as well as static branch prediction circuitry configured to generate a branch prediction based on static branch prediction information. Prediction output circuitry, coupled to the both the dynamic and static branch prediction circuitry, outputs the respective branch predictions for the first and second branch instructions in first and second clock cycles to an instruction buffer (or "rotator"). Specifically, the prediction output control circuitry outputs the branch prediction for the second branch instruction in the second clock cycle and in response to the initiation of a recycle stall during the first clock cycle. The receipt of the predictions and their corresponding branch instructions at the instruction buffer is thus synchronized, and the opportunity of generating a prediction for the second branch instruction is not lost.