1. Introduction

Abstract

Constant propagation is one of the most widely used optimizations in practice (cf. [2, 30, 56]). Its goal is to replace expressions that always yield a unique constant value at run-time by this value. This transformation can both speed up execution and reduce code size by replacing a computation or memory access by a load-constant instruction. Often constant propagation enables powerful further program transformations. An example is branch elimination: if the condition guarding a branch of a conditional can be identified as being constantly false, the whole code in this branch is dynamically unreachable and can be removed.