ARM Assembly Language, 2nd Edition

Chapter 8

Branches and Loops

8.1 Introduction

Branches are a necessary evil. Software cannot avoid using them, and hardware engineers treat them as anathema. So much so that computer architects will go to extreme lengths to get rid of them. In fact, researchers spend years and years trying to come up with new strategies to either predict their effects before they arrive or avoid them entirely. A quick read through most computer architecture literature will highlight the elaborate hardware that is included with every modern design: static branch predictors, dynamic branch predictors, two-level adaptive branch predictors, instruction trace caches—the research continues. Certainly, ARM is no stranger to the phenomenon. However, the whole notion ...