5. The importance of having a good branch predictor depends on how often conditional branches are executed. Together with bra 5. The importance of having a good branch predictor depends on how often conditional branches are executed. Together with branch predictor accuracy, this will determine how much time is spent stalling due to mispredicted branches. In this exercise, assume that the breakdown of dynamic instructions into various instuction categories is as follows: JMP R-Type ВЕQ LW sW 45% 20% 5% 20% 10% Also, assume the following branch predictor accuracies: Always-Taken Always-Not-Taken 2-Bit 45% 55% 85% 5.1 Stall cycles due to mispredicted branches increase the CPI. What is the extra CPI due to mispredicted branches with the always-taken predictor? Assume that branch outcomes are determined in the EX stage, that there are no data hazards, and that no delay slots are used 5.2 Repeat 5.1 for the “always-not-taken” predictor. 5.3 Repcat 5.1 for for the 2-bit predictor. 5.4 With the 2-bit predictor, what speedup would be achieved if we could convert half of the branch instructions in a way that replaces a branch instruction with an ALU instruction? Assume that correctly and incorrectly predicted instructions have the same chance of being replaced



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