Writing Efficient Programs

Abstract

The primary task of software engineers is the cost-effective development of maintainable and useful software. There are many secondary problems lurking in that definition. One such problem arises from the term useful: to be useful in the application at hand, software must often be efficient (that is, use little time or space). The problem we will consider in this book is building efficient software systems. There are a number of levels at which we may confront the problem of efficiency. These are defined in Section 1.2 and include the overall system design, the program's algorithms and data structures, the translation to machine code, and the underlying system software and hardware; many books discuss efficiency. at each of those levels. In this book we will investigate efficiency at a design level that is practiced by many but discussed by few. This level is called efficient and can be defined as follows: The activity of writing efficient code takes as input a high-level language program (which incorporates efficient algorithms and data structures) and produces as output a program in the same high-level language that is suitable for compilation into efficient machine code. The operations undertaken at this level are beneath most work on algorithms and data structures yet are too complex for most current and foreseeable compilers.