bf

This is an optimizing compiler for brainfuck. It's mostly a toy for playing with optimization and code generation.

Usage

bf reads a brainfuck program from stdin and writes AT&T assembler to stdout.

bf < program.bf > program.s

The assembler can be assembled with gcc (and possibly others, but that's completely untested).

gcc -nostdlib program.s -o program

The -nostdlib flag is required since _start is defined directly in the assembler and the stdlib typically tries to define its own.

Optimizations

• Combining adjacent operations
  • For example, ++-++-++- becomes +3.
• Making "fixed loops" run in a single pass.
  • A "fixed loop" is a loop without IO where the cursor is at the same position for each instruction for each iteration of the loop.
  • This means operations can be easily combined across loop iterations.
  • For example, +[>+<+] would become + > +255 < +255.
• Removing cursor movements
  • Instead, instructions can be encoded with offsets.
  • For example, +>>>>+<<<< would become +(0) +(4)