[PATCH] D40831: [AArch64] Only use writeback in the load/store optimizer when needed

[Matthias Braun via Phabricator via llvm-commits]

MatzeB added a comment.

Yes please don't add new code that relies on kill flags, you will see them used less and less, your code will be less and less effective.

Post-RA you should perform all your liveness query needs with LiveRegUnits (or LivePhysRegs). They allow you to start from the end of a basic block where we have live-out information (it's actually live-in information of the successors) and simulating liveness while walking backwards to the point you are interested in. You have to be a bit careful about the performance implications (ideally you change your highlevel algorithms to work backwards through basic blocks as well so you only simulate once for all transformations you do in a basic block rather than simulating anew for every single transformation you perform).


Repository:
  rL LLVM

https://reviews.llvm.org/D40831