Self-Modifying code for user settings optimization

[Rikki Cattermole via Digitalmars-d]

I've been looking into this issue for web routing.
Over all its definitely more performant.

But:
- You need some way to generate code
- ABI compatibility
- Host binary compatibility (not the same as ABI)
- Front end for the "language" to specify what to generate

I'm either going sljit way or my own.
ATM I'm looking at building a c frontend to help with porting of sljit 
and for the future AOT generation of binaries.

Most of the work to get x86 done for sljit has been done, about 2-3k left.
https://github.com/rikkimax/sljitd

Regarding if CPU's allow for JIT'ing code, yup they do allow it still.
If they didn't, that CPU would be next to useless.

However, an OS is not required to expose this. But if you're dealing 
with Windows and *nix. Don't worry about it.

If you're interested in working on helping to port sljit please do.
Just note that it isn't a very optimized JIT but it is fairly small and 
easy to use. Important to me is that it can be fully ported to D without 
much worries unlike LLVM, which is a pain to compile anyway.