[PATCH] D79100: [LV][TTI] Emit new IR intrinsic llvm.get.active.mask for tail-folded loops

[Florian Hahn via Phabricator via llvm-commits]

fhahn added a comment.

In D79100#2054437 <https://reviews.llvm.org/D79100#2054437>, @SjoerdMeijer wrote:

> Thanks Eli for commenting and explaining.
>
> I guess it was the TODO in VPlan.cpp that looked a bit suspicious. But there wasn't much going on here, that was very straightforward. so fixed that. I.e., Ayal added support for decrementing loops in VPlan recently. The Backedge Taken Count value looks slightly different for these cases, but extracting it is easy which I have added here. As a result, this now also triggers in `test/Transforms/LoopVectorize/ARM/tail-folding-counting-down.ll` which I updated


I think introducing a VPInstruction opcode for the new intrinsic makes sense and fits in the current scheme. But I think there's no need to bundle the langref, TTI and LV changes into a single patch. IMO would be good to split at least the LV part off, to focus on discussing the implementation details in LV there.


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https://reviews.llvm.org/D79100