Optimized C++

The world has a stupendous appetite for computation. Whether the code you are writing runs on a watch, phone, tablet, workstation, supercomputer, or planetspanning network of data centers, there are many programs that must run flat-out all the time. So it may not be enough merely to accurately convert the cool idea in your head into lines of code. It may not be enough even to comb the code for defects until it runs correctly all the time. Your application may be sluggish on the kind of hard‐ ware your customers can afford. Your hardware team may have saddled you with a tiny processor to meet their power consumption goals. You may be battling a compet‐ itor over throughput or frames per second. Or you may be building out to planetary scale and just slightly nervous about boiling the oceans. Enter optimization. This book is about optimization—specifically, optimizing C++ programs, with partic‐ ular reference to patterns of behavior of C++ code.

Some of the techniques in this book are applicable to other programming languages, but I have made no attempt to explain the techniques in a universal way. Some optimizations that are effective on C++ code have no effect or are simply not possible in other languages. This book is about taking correct code that embodies best practices of C++ design, and changing it into correct code that still embodies good C++ design but also runs faster and consumes fewer resources on pretty much any computer. Many opportuni‐ ties for optimization occur because some C++ features, used casually, run slowly and consume many resources. Such code, while correct, is ill-considered, given just a little general knowledge about modern microprocessor devices or a little thought about the costs of various C++ constructs. Other optimizations are available because of the fine control C++ offers over memory management and copying.