State machine-based filtering of pattern history tables based on distinguishable pattern detection

Abstract

Machine-based filtering of a pattern history table includes identifying a matching previous occurrence of a current branch instruction in an address history vector (AHV), the AHV storing addresses, or partial addresses, of most recently occurring branch instructions. In response to determining a direction history of the previous occurrence matches a direction history of the current branch, the machine-based filtering includes comparing the outcome of the previous occurrence with the outcome of the current branch instruction, and preventing the pattern history table from being updated with the outcome of the current branch instruction when the outcome of the previous occurrence does not match the outcome of the current branch instruction.