An optimizing compiler for Brainfuck.
Many patterns of loops are recognized and transformed into the closed form arithmetic expressions they compute.
Architecturally, its intermediate representation is very similar to the design of Cranelift: It has a control-flow graph with effectful nodes strictly ordered in basic blocks and pure values ordered by data dependencies, i.e., a control data flow graph. Pure values are managed in an arena with global value-numbering and are rewritten to an idealized form on construction.
See the Brainfuck Program Corpus for a large collection of Brainfuck programs.