[PATCH] D102615: [LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration (try 3)

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

After looking through the tests, why does this need to use SCEV at all? As far as I can tell, simply using InstSimplify would be sufficient to prove all these cases (or just ConstFold for that matter). Without isKnownPredicateAt(), where symbolic reasoning is necessary, SCEV doesn't seem to provide much value here, or at least it's not obvious from the tests. (Of course, there will be cases where it can do more, but the converse also holds -- in particular, InstSimplify/ConstFold support arbitrary instructions, no need to special-case a limited set of them.)


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https://reviews.llvm.org/D102615