[llvm] LV]: consider scalable VF during deciding dead epilogue. (PR #156724)

[David Sherwood via llvm-commits]

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@@ -4407,6 +4407,13 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
     LLVM_DEBUG(dbgs() << "LEV: Maximum Trip Count for Epilogue: "
                       << MaxTripCount << "\n");
   }
+  // Check if the RemainingIterations is scalable.
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david-arm wrote:

It's about how common it is, but more about the complexity of the code and the missing cases. Im my opinion, I think if we proceed with this approach there still needs to be some changes because I don't think it really makes sense to try comparing values in different spaces without using estimates.

https://github.com/llvm/llvm-project/pull/156724