Advanced Computer Architecture, Imperial
College 2001
Global history
•Definition:
Global history. The taken - not-taken history for all
previously-executed branches.
•Idea:
use global history to improve branch prediction
•Compromise: use m most
recently-executed branches
•Implementation:
keep an m-bit Branch History Register (BHR) - a shift register
recording taken - not-taken direction of the last m branches
•Question: How to combine local
information with global information?