Building blocks of a compiler

Since computers became available, thousands of programming languages have been developed. It turns out that all compilers must solve the same tasks and that the implementation of a compiler is best structured according to these tasks. At a high level, there are three components. The frontend turns the source code into an intermediate representation (IR). Then the middle end performs transformations on the IR, with the goal of either improving performance or reducing the size of the code. Finally, the backend produces machine code from the IR. The LLVM core libraries provide a middle end consisting of very sophisticated transformations and backends for all popular platforms. Furthermore, the LLVM core libraries also defines an intermediate representation used as input for the middle end and the backend. This design has the advantage that you only need to care about the frontend for the programming language you want to implement.

The input for the frontend...