Lecture Notes on Loop Transformations for Cache Optimization 15-411: Compiler Design

In this lecture we consider loop transformations that can be used for cache optimization. The transformations can improve cache locality of the loop traversal or enable other optimizations that have been impossible before due to bad data dependencies. Those loop transformations can be used in a very flexible way and are used repeatedly until the loop dependencies are well aligned with the memory layout and cache effects are optimal. What is most important, however, is to keep track carefully under which circumstances the loop transformations are actually correct. We will pay attention to that. The same loop transformations are needed for loop parallelization and vectorization.