[PATCH] D46756: [AMDGPU] Reworked SIFixWWMLiveness

[Tim Renouf via Phabricator via llvm-commits]

tpr added a comment.

Actually that plan does not work for one of the cases handled in the current change: when there is a def towards the end of a loop and a use outside the loop, and there is some WWM inside the loop. There is no phi node at the top of the loop at all for that, but we need to spot the case and introduce one (and make its value undef from the loop pre-header) because the liveness needs to go round the loop to allow for lanes that were in the loop but have become inactive because they have already decided to leave the loop.


Repository:
  rL LLVM

https://reviews.llvm.org/D46756