The document introduces a Brainf**k interpreter called fast-bf that is the fastest existing Brainf**k interpreter. It benchmarks fast-bf against other interpreters on a Mandelbrot set generating Brainf**k program, showing that fast-bf with just-in-time compilation and optimizations runs over 4 times faster than the next fastest interpreter. The document also provides examples of optimizations performed in fast-bf like replacing multiple increment operations with a single addition and removing unnecessary branching. Faster optimizations and implementations are welcome if they can outperform fast-bf.

1. hogelog
http://hogel.org/
http://twitter.com/hogelog

2. Where is fastest
BF interpreter?

3. It’s here!
https://github.com/
hogelog/fast-bf

4. Demo

5. http://esoteric.sange.fi/brainfuck/utils/mandelbrot
/mandelbrot.b

6. Existing fastest(?) BF interpreter
$ time ./bff4 <sample/mandelbrot.b
real 0m8.525s
user 0m8.457s
sys 0m0.004s

7. Interpret with JIT
$ time ./bf-jit <sample/mandelbrot.b
real 0m3.906s
user 0m3.860s
sys 0m0.000s
Faster!

8. Interpret with optimizations
$ time ./bf-vm-opt <sample/mandelbrot.b
real 0m3.770s
user 0m3.724s
sys 0m0.000s
Faster!

9. Interpret with JIT, optimizations
$ time ./bf-jit-opt <sample/mandelbrot.b
real 0m1.573s
user 0m1.540s
sys 0m0.000s
Fastest!

10. If any other faster,
It’s bug!

11. throw New Issue

12. Appendix A:
Brainf**k
Design Pattern

13. ++++++++++
*ptr += 10

14. >>>>>>>>>>
ptr += 10

15. [-]
*ptr = 0

16. [>+<-]
*(ptr+1) += *ptr
*ptr = 0

17. Appendix B:
Brainf**k
Optimization

18. BF: ++++++++++
Interpret: ++*ptr;++*ptr; …
Fetch
Instruction
Eval
Increment
Fetch
Instruction
Eval
Increment
…
10 Instructions

19. BF: ++++++++++
Interpret: *ptr += 10
Fetch Eval
Instruction Calc +10
1 Instruction

20. BF: >>>>>>>>>>
Interpret: ++ptr;++ptr; …
Fetch
Instruction
Eval
Next
Fetch
Instruction
Eval
Next
…
10 Instructions

21. BF: >>>>>>>>>>
Interpret: ptr += 10
Fetch Eval
Instruction Move +10
1 Instruction

22. BF: [-]
Interpret:
if(!*ptr) goto ];--*ptr;goto [;
Fetch Jump If Fetch Eval Fetch
Jump
Instruction Zero Instruction Decrement Instruction
Contains Branch

23. BF: [-]
Interpret: *ptr = 0
Fetch Eval
Instruction Reset Zero
1 Instruction, No Branch

24. And others
https://github.com/
hogelog/fast-bf