[PATCH] D114650: [SCEV] Construct SCEV iteratively (WIP).

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

I want to make sure I understand the problem to be solved.  The description and discussion confused me a bit, so I may in fact be wildly off here.

Is the basis issue being solved that calling createSCEV on some IR instruction can require recursing through a very deep chain of instructions which have not yet had SCEVs formed for them?  More specifically, is that the *only* deep recursion we're concerned by?  The discussion about new invariants for creating a SCEV seemed to indicate it might be much wider, but that discussion didn't parse for me.

If my understanding is correct, then I would have expected this to be effectively a change strictly inside createSCEV.  The fact we seem to be changing things much more broadly confuses me.  Maybe there's some complexity coming from the phi handling, but if so, maybe a first patch which *only* iteratively constructs arithmetic chains and relies on recursion for the tricky phi parts?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D114650/new/

https://reviews.llvm.org/D114650