[PATCH] D119558: [SCEV] Add SCEVCompareExpr node

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

> I want to highlight that adding the node does not mean we have to extend IR pattern matching. At the moment, I'm planning on using this to simplify and generalize PredicatedScalarEvolution and the loop versioning checks used by various transforms. The decision as to whether we want these in generic SCEV expressions can (and should be) explicitly deferred here.

Could you provide a bit more information on how this is going to be used? It's not completely clear to me whether/why this should be part of the SCEV hierarchy, rather than something that uses SCEV nodes but is not one itself.

Having it as a SCEV makes sense if you want to make it a part of a larger expression, but it's not immediately obvious how that will look in practice (I guess you could use umin/umax as an awkward way to and/or conditions).


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  https://reviews.llvm.org/D119558/new/

https://reviews.llvm.org/D119558