> What are typically the speed gains that are possible with dynarec?
It depends on the system, the processor being emulated, and the nature of the code. The speed gains can be very high in the right situations.
> I'm thinking about doing dead flag removal as well, but I have the feeling it
> might not make much of a difference when doing it in java since these kinds of
> things are typically those things that HotSpot should be very good at.
Dead flag removal is definitely an optimization that's worthwhile for many older CISC processors with lots of flags (especially 68K.)
> Does anybody have experience with this, and especially using java? Is there some
> good documentation somewhere about dynarec techniques that I should be aware
> about? Thoughts, suggestions?
I don't know anything about using Java but you might want to turn to the dynarec mailing list if you want to discuss the subject.