What should a good predictor do?

• In previous example if both b1 and b2 are Taken, b3 should be Not-Taken

• A two-bit counter scheme cannot predict this behavior.

• Needs history of previous branches hence correlated schemes for BPT’s

  • Requires history of n previous branches (shift register)
  • Use of this vector (maybe more than one) to index a Pattern History Table (PHT) (maybe more than one)

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