Computers as Components, 3rd Edition

5.7 Software Performance Optimization

In this section we will look at several techniques for optimizing software performance, including both loop and cache optimizations as well as more generic strategies.

5.7.1 Loop Optimizations

Loops are important targets for optimization because programs with loops tend to spend a lot of time executing those loops. There are three important techniques in optimizing loops: code motion, induction variable elimination, and strength reduction.

Code motion lets us move unnecessary code out of a loop. If a computation’s result does not depend on operations performed in the loop body, then we can safely move it out of the loop. Code motion opportunities can arise because programmers may find some computations clearer ...