[PATCH] D116554: [VPlan] Add & use utility to check if only the first lane is used.

[David Sherwood via Phabricator via llvm-commits]

david-arm added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/VPlan.cpp:1658
+
+bool VPUtils::onlyFirstLaneDemanded(VPValue *Def) {
+  return all_of(Def->users(), [](VPUser *U) {
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Hi @fhahn, on the face of it this looks like a reasonable change, but I'm just wondering if we're now going to have to update two places in the code when someone makes a change to `isUniformAfterVectorization`. For example, can we guarantee that for all cases where `isUniformAfterVectorization` returns true we will generate a VPReplicateRecipe that is uniform? 

During creations of vplans is there a way to assert that if `isUniformAfterVectorization` returns true then VPUtils::onlyFirstLaneDemanded should also be true?


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Comment at: llvm/lib/Transforms/Vectorize/VPlan.h:2748
 
+struct VPUtils {
+  VPUtils() = delete;
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Given you can't create an instance of this, does it even need to be a struct? Could you just use a namespace VPUtils instead?


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D116554/new/

https://reviews.llvm.org/D116554