Exploiting Postdominance for Speculative Parallelization

Task-selection policies are critical to the performance of any architecture that uses speculation to extract parallel tasks from a sequential thread. This paper demonstrates that the immediate postdominators of conditional branches provide a larger set of parallel tasks than existing taskselection heuristics, which are limited to programming language constructs (such as loops or procedure calls). Our evaluation shows that postdominance-based task selection achieves, on average, more than double the speedup of the best individual heuristic, and 33% more speedup than the best combination of heuristics. The specific contributions of this paper include, first, a description of task selection based on immediate postdominance for a system that speculatively creates tasks. Second, our experimental evaluation demonstrates that existing task-selection heuristics based on loops, procedure calls, and if-else statements are all subsumed by compilergenerated immediate postdominators. Finally, by d...

• Type: Conference
• Year: 2007
• Where: HPCA
• Authors: Mayank Agarwal, Kshitiz Malik, Kevin M. Woley, Sam S. Stone, Matthew I. Frank
• Keywords: Computer Architecture, Dynamic Task Selection, HPCA 2007, Immediate Postdominator Analysis, Immediate Postdominators