[PATCH] D67948: [LV] Interleaving should not exceed estimated loop trip count.

[Hideki Saito via Phabricator via llvm-commits]

hsaito added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:5213
   // Do not interleave loops with a relatively small trip count.
-  unsigned TC = PSE.getSE()->getSmallConstantTripCount(TheLoop);
-  if (TC > 1 && TC < TinyTripCountInterleaveThreshold)
+  auto BestKnownTC = getSmallBestKnownTC(*PSE.getSE(), TheLoop);
+  if (BestKnownTC && *BestKnownTC < TinyTripCountInterleaveThreshold)
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This assumes constant trip count case is handled well by getSmallConstantMaxTripCount called from getSmallBestKnownTC ---- but if that is not the case, that would be a bug on the SCEV side. I traced a little bit but could not verify it myself as I'm not familiar with SCEV code. As such, I'm just pointing out a different SCEV function will be called as a result of this change.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67948/new/

https://reviews.llvm.org/D67948