Collaboration Summit 2014

The GCC compiler is, since its 4.5 release, customizable and extensible through plugins. This talk introduces some of the GCC internal representations (Gimple-s, Tree-s ...) and organization into passes, from the perspective of a plugin writer not yet knowing well GCC internals. We explain what GCC plugins could be useful for, what are the existing plugin hooks in the latest versions of the compiler, how to use them effectively, and for which purposes they can be exploited. We use the MELT meta-plugin as an example: MELT is a high-level compiled lisp-like domain specific language (translated into C++ code fitted to GCC internals) to facilitate the development of useful GCC extensions, bringing powerful features (functional & reflective programming styles, powerful pattern matching on GCC internal representations) to lower the effort to extend GCC.