Dynamic memory interval test vs. interprocedural pointer analysis in multimedia applications
Techniques to detect aliasing between access patterns of array elements are quite effective for many numeric applications. However, although multimedia codes usually follow very regular memory access patterns, current commercial compilers remain unsuccessful in disambiguating them due mainly to complex pointer references. The Dynamic Memory Interval Test is a runtime memory disambiguation technique that takes advantage of the specific behavior of multimedia memory access patterns. It evaluates whether or not the full loop is disambiguated by analyzing the region domain of each load or store before each invocation of the loop.This paper provides a detailed evaluation of the approach, compares it against an advanced interprocedural pointer analysis framework, and analyzes the possibility of using both techniques at the same time. Both techniques achieve similar speedups separately (1.25X in average for a 8-issue width architecture). Furthermore, they can be used together to improve performance (reaching an average speed-up of 1.32X). Results also confirm that memory disambiguation is a key optimization to exploit the available parallelism in multimedia codes, especially for wide-issue architectures (1.50X average speed-up when scaling from 4- to 12-issue width in contrast to a low 1.10X for the baseline compiler).