[PATCH] D67805: [LV] Allow vectorization of hot short trip count loops with epilog

[Evgeniy via Phabricator via llvm-commits]

ebrevnov marked an inline comment as done.
ebrevnov added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7411
+        if (LoopCount && FunctionCount &&
+            (*LoopCount > *FunctionCount * LocalHotnessThreshold)) {
+          LLVM_DEBUG(dbgs() << "Allow epilog for short trip count loop due to "
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Some rational for the chosen heuristic. In general if nobody actually asked to optimize for size it seems reasonable to relay on cost model to decide if vectorization is profitable or not even for short trip count loops. If we still want to have some balance between code bloat and performance we should decide based on potential gain and loop size for all loops. Even though the described approach looks simple and reasonable in theory it most likely will have big implications on existing apps. That's why I decided take more conservative approach and give a chance for hot loops to be vectorized. 


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https://reviews.llvm.org/D67805