Scalar Optimization

An optimizing compiler improves the quality of the code that it generates by applying transformations to rewrite the code. “Quality” might be measured in runtime speed, in code size, or in more complex metrics, such as the energy expended by the processor at runtime. This chapter builds on the introduction to optimization provided in Chapter 8 and the material on static analysis in Chapter 9 to focus on optimization of the code for a single thread of control—so-called scalar optimization. The chapter introduces a selection of machine-independent scalar transformations that address a variety of inefficiencies in compiled code.