Interesting! I just read [1] this morning, which describes an optimizing BF compiler (written in Rust) that compiles to LLVM IR. The article also gives a good overview of optimization techniques used.

[1]: http://www.wilfred.me.uk/blog/2015/08/29/an-optimising-bf-co...

Edit: Just saw this was also discussed on HN: https://news.ycombinator.com/item?id=10141604

Nice work; how about optimising the C output? Ten plusses in a row can be shortened to *p+=10 for example.