[PATCH] D72714: [ARM][MVE] WIP: Tail-Predication: rematerialise iteration count in exit blocks

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added a comment.

Thanks for sharing your thoughts!

So I had also not realised that this requires LCSSA, and for a bit more context: in my first experiment, I was running the whole `IndVarSimplify` pass directly after `MVETailPredicationPass`, which takes care of bringing it in LCSSA form as this is a required pre-condition for a few things. The more focused approach, only using `rewriteLoopExitValues()` as a helper which is what this patch is about, and not running `IndVarSimplify`, this LCSSA assert was triggered.

I will now look into this, and thanks for your suggestions: if it is just calling `formLCSSA()` that would be ideal, but if that is a bit overkill I will just insert the Phi.


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