A Loop Transformation Algorithm Based on Explicit Data Layout Representation for Optimizing Locality

  • Authors:
  • Mahmut T. Kandemir;J. Ramanujam;Alok N. Choudhary;Prithviraj Banerjee

  • Affiliations:
  • -;-;-;-

  • Venue:
  • LCPC '98 Proceedings of the 11th International Workshop on Languages and Compilers for Parallel Computing
  • Year:
  • 1998

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Abstract

We present a cache locality optimization technique that can optimize a loop nest even if the arrays referenced have different layouts in memory. Such a capability is required for a global locality optimization framework that applies both loop and data transformations to a sequence of loop nests for optimizingl ocality. Our method finds a nonsingular iteration-space transformation matrix such that in a given loop nest spatial locality is exploited in the innermost loops where it is most useful. The method builds inverse of a non-singular transformation matrix column-by-column startingfrom the rightmost column. In addition, our approach can work in those cases where the data layouts of a subset of the referenced arrays is unknown. Experimental results on an 8-processor SGI Origin 2000 show that our technique reduces execution times by up to 72%.