Write Great Code, Volume 2

Chapter 7. Constants and High-Level Languages

Some programmers may not realize it, but many CPUs do not treat constant and variable data identically at the machine-code level. Most CPUs provide a special immediate addressing mode that lets a language translator incorporate a constant value directly into a machine instruction rather than storing that constant’s value in a memory location and accessing it as a variable. However, the ability to represent constant data efficiently varies by CPU and, in fact, by the type of the data. By understanding how a CPU represents constants at the machine-code level, you can appropriately represent constants in ...