International Business Machines Corporation
Predicting a branch instruction classified as simple or hard to predict based on a confidence counter in a branch type table

Abstract:

A processor including a processor pipeline having one or more execution units configured to execute branch instructions, a branch predictor coupled to the processor pipeline and configured to predict a branch instruction outcome, and a branch classification unit coupled to the processor pipeline and the branch predictor. The branch classification unit is configured to, in response to detecting a branch instruction, classify the branch instruction as at least one of the following: a simple branch and a hard-to-predict branch. The branch classification unit includes a direct mapped branch type table (BTT) and a branch classification table (BCT).