Optimization in GCC
Marc Jones · Linux journal · 2005
Let's first look at how GCC categorizes optimizations and how a developer can control which are used and, sometimes more important, which are not. A large variety of optimizations are provided by GCC. Most are categorized into one of three levels, but some are provided at multiple levels. Some optimizations reduce the size of the resulting machine code, while others try to create code that is faster, potentially increasing its size. For completeness, the default optimization level is zero, which provides no optimization at all. This can be explicitly specified with option -O or -O0.