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Page 234 If we guess in-line and go to the target, we have: In-line penalty = 0 cycles Target penalty = 6 cycles If we guess the target and go in-line we have: If we guess the target and go to the target, we have: In-line penalty = 5 cycles Target penalty = 3 cycles Let P = the probability of branch going to target. Then expected in-line delay is 6P + 0(1 P). expected target delay is 3P + 5(1 P). Then we should guess the target path if 3P + 5(1- P) < 6 P ® P > 5/8 (c) For BR (unconditional) or for BAL: Target penalty = 4 cycles (d) For BC (conditional branch): If we guess in-line and go in-line: that is, zero penalty. If we guess in-line and go to target: In-line penalty = 0 cycles Target penalty = 6 cycles If we guess target and go in-line:* * Assumes in-line instructions already fetched are kept in IB. If we guess target and go to target:
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