LLVM: Improve alias analysis / performance
- LLVM doesn't generate as good as code as we feel it should in many situations
- We've often felt its a alias anlysis issue.
- I'm a little more doubtful of that than others (I feel its part of the bigger problem, not the whole thing).
- I think there may be some register allocation / instruction selection / live range splitting issue going on.
- We could also do with looking at what optimisation passes we should run and in what order...
Here is some work Max did on the alias issue, his results for nofib weren't good:
So this ticket is just a high level ticket about figuring out and improving the performance of LLVM backend.