2003 12th International Conference on Parallel Architectures and Compilation Techniques (2003)
New Orleans, Louisiana
Sept. 27, 2003 to Oct. 1, 2003
Nicholas Wang , University of Illinois at Urbana-Champaign
Michael Fertig , University of Illinois at Urbana-Champaign
Sanjay Patel , University of Illinois at Urbana-Champaign
<p>In this paper, we study the effects of manipulating the architected direction of conditional branches. Through the use of statistical sampling, we .nd that about 40% of all dynamic branches and about 50% of mispredicted branches do not affect correct program behavior when forced down the incorrect path. We call such branches Y-branches.</p> <p>To further examine this unexpected phenomenon, we provide a characterization of the coding constructs that give rise to such branches. Examples of such coding constructs include short-circuits and ineffectual loop iterations. We provide a statistical breakdown of the frequency of these branches and their constructs. Finally, we suggest some techniques for exploiting this behavior, particularly when it results from short-circuit constructs.</p>
M. Fertig, N. Wang and S. Patel, "Y-Branches: When You Come to a Fork in the Road, Take It," 2003 12th International Conference on Parallel Architectures and Compilation Techniques(PACT), New Orleans, Louisiana, 2003, pp. 56.