Handling Irreducible Loops: Optimized Node Splitting vs DJ-Graphs.

Unger, S. ; Mueller, F.

Technical Information Center Oak Ridge Tennessee

关键词: Loops;    Optimization;    Graphs;    Scheduling;    Splitting;   

RP-ID  :  DE200415006265

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

This paper addresses the question of how to handle irreducible regions during optimization, which has become even more relevant for contemporary processors since recent VLIW-like architectures highly rely on instruction scheduling. The contributions of this paper are twofold. First, a method of optimized node splitting to transform irreducible regions of control flow into reducible regions is derived. This method is superior to approaches previously published since it reduces the number of replicated nodes by comparison. Second, three methods that handle regions of irreducible control flow are evaluated with respect to their impact on compiler optimizations: traditional and optimized node splitting as well as loop analysis through DJ graphs. Measurements show improvements of 1-40% for these methods of handling irreducible loop over the unoptimized case.