[PATCH] D60093: [LoopPredication] Allow predication of loop invariant computations

Philip Reames via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Apr 5 16:21:01 PDT 2019


reames planned changes to this revision.
reames added a comment.

In D60093#1453993 <https://reviews.llvm.org/D60093#1453993>, @apilipenko wrote:

> 2. Invariant expression analysis over IR is a bit non-trivial. It looks like extending SCEV would be a simpler option. Alternatively, we can build up the complexity of the IR analysis incrementally as I suggest in the comment below.


I started prototyping the SCEV change, and found one downside.  Because SCEV doesn't have access to AA, I can't use the pointsToConstantMemory as I do with the current scheme.  I think this is a fairly minor impact since loads from constant memory which can't be proven trivial dereferenceable should be rare, but I'd like a second opinion on that.

(Also, marking as plan changes so that this shows up in my queue of things to do)


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60093/new/

https://reviews.llvm.org/D60093





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