Examine the accuracy of the following branch predictors for this repeated pattern (in a loop) of branch outcomes: T, NT, T, T, NT. (24 pts) 4. What is the accuracy of the always-taken and always-not-taken branch predictors for this sequence of branch outcomes? (4 pts) a. b. What is the accuracy of the 2-bit branch predictor for the first 4 branches (T, T) in the pattern above. Assume we start in the "predict strongly not taken" state. (4 pts) NT, T, What is the accuracy of the 2-bit branch predictor if this pattern is repeated forever? (4 pts) c. d. Design a predictor that would achieve a perfect accuracy if this pattern is repeated forever. Your predictor should be a sequential circuit with one output that provides a prediction (1 for taken, O for not taken) and no inputs other than the clock and the control signal that indicates that the instruction is a conditional branch. (4 pts) What is accuracy of the predictor above if it is given a repeating pattern that is the exact opposite of this one? (4 pts) e. f. Repeat the predictor above, but now your predictor should be able to eventually (after a warm-up period during which it can make wrong predictions) start perfectly predicting both this pattern and its opposite. Your predictor should have an input that tells it what the real outcome was. Hint: this input lets your predictor determine which of the two repeating patterns it is given. (4 pts) Examine the accuracy of the following branch predictors for this repeated pattern (in a loop) of branch outcomes: T, NT, T, T, NT. (24 pts) 4. What is the accuracy of the always-taken and always-not-taken branch predictors for this sequence of branch outcomes? (4 pts) a. b. What is the accuracy of the 2-bit branch predictor for the first 4 branches (T, T) in the pattern above. Assume we start in the "predict strongly not taken" state. (4 pts) NT, T, What is the accuracy of the 2-bit branch predictor if this pattern is repeated forever? (4 pts) c. d. Design a predictor that would achieve a perfect accuracy if this pattern is repeated forever. Your predictor should be a sequential circuit with one output that provides a prediction (1 for taken, O for not taken) and no inputs other than the clock and the control signal that indicates that the instruction is a conditional branch. (4 pts) What is accuracy of the predictor above if it is given a repeating pattern that is the exact opposite of this one? (4 pts) e. f. Repeat the predictor above, but now your predictor should be able to eventually (after a warm-up period during which it can make wrong predictions) start perfectly predicting both this pattern and its opposite. Your predictor should have an input that tells it what the real outcome was. Hint: this input lets your predictor determine which of the two repeating patterns it is given. (4 pts)
