Introduction to Compiler Construction in a Java World

Chapter 7

Register Allocation

7.1 Introduction

Register allocation is the process of assigning as many local variables and temporaries to

physical registers as possible. The more values that we can keep in registers instead of in

memory, the faster our programs will run. This makes register allocation the most effective

optimization technique that we have.

With respect to our LIR discussed in Chapter 6, we wish to assign physical registers

to each of the virtual registers that serve as operands to instructions. The problem is that

there are often many fewer physical registers than there are virtual registers. Sometimes,

as program execution progresses, ...