LLVM Cookbook

Understanding modular design

LLVM is designed as a set of libraries unlike other compilers such as GNU Compiler Collection (GCC). In this recipe, LLVM optimizer will be used to understand this design. As LLVM optimizer's design is library-based, it allows you to order the passes to be run in a specified order. Also, this design allows you to choose which optimization passes you can run—that is, there might be a few optimizations that might not be useful to the type of system you are designing, and only a few optimizations will be specific to the system. When looking at traditional compiler optimizers, they are built as a tightly interconnected mass of code, that is difficult to break down into small parts that you can understand and use easily. ...