[PATCH] D99750: [LV, VP]VP intrinsics support for the Loop Vectorizer

[Alexey Bataev via Phabricator via llvm-commits]

ABataev added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:8112
   // When not folding the tail, use nullptr to model all-true mask.
-  if (!CM.foldTailByMasking()) {
+  if (!CM.foldTailByMasking() || CM.useVPIVectorization()) {
     BlockMaskCache[Header] = nullptr;
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fhahn wrote:
> Better to replace the mask together with introducing EVL to make sure EVL gets added when the mask gets removed?
Currently it will require some extra work. We'll need to handle both cases, with activelane instrnsics and direct comparison. Would be possible to keep it for now and fix it once you land emission of activelane intrinsic in VPlan-toVPlan transform?


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Comment at: llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp:832
+      continue;
+    auto *NewInst =
+        new VPInstruction(VPInstruction::ExplicitVectorLengthIVIncrement,
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fhahn wrote:
> I think turning the step of the canonical induction non-loop-invariant technically turns the canonical IV into a phi that's not a canonical IV any more (which is guaranteed to step the same amount each iteration). Would it work to keep the increment unchanged and keep rounding up the trip count was with regular tail folding initially? Further down the line, the canonical IV issue may be resolved by also replacing the canonical IV node with a regular scalar phi when doing the replacement here.
I'll try to improve this.


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  https://reviews.llvm.org/D99750/new/

https://reviews.llvm.org/D99750