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Proceedings.International Conference on Parallel Architectures and Compilation Techniques (2002)
Charlottesville, Virginia
Sept. 22, 2002 to Sept. 25, 2002
ISSN: 1089-795X
ISBN: 0-7695-1620-3
pp: 18
Samuel Larsen , Massachusetts Institute of Technology
Emmett Witchel , Massachusetts Institute of Technology
Saman Amarasinghe , Massachusetts Institute of Technology
<p>A static memory reference exhibits a unique property when its dynamic memory addresses are congruent with respect to some non-trivial modulus. Extraction of this congruence information at compile-time enables new classes of program optimization. In this paper, we present methods for forcing congruence among the dynamic addresses of a memory reference. We also introduce a compiler algorithm for detecting this property. Our transformations do not require interprocedural analysis and introduce almost no overhead. As a result, they can be incorporated into real compilation systems.</p> <p>On average, our transformations are able to achieve a five-fold increase in the number of congruent memory operations. We are then able to detect 95% of these references. This success is invaluable in providing performance gains in a variety of areas. When congruence information is incorporated into a vectorizing compiler, we can increase the performance of a G4 AltiVec processor up to a factor of two. Using the same methods, we are able to reduce energy consumption in a data cache by as much as 35%.</p>

S. Amarasinghe, S. Larsen and E. Witchel, "Increasing and Detecting Memory Address Congruence," Proceedings.International Conference on Parallel Architectures and Compilation Techniques(PACT), Charlottesville, Virginia, 2002, pp. 18.
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