[LV]: Ensure fairness when selecting epilogue VF. (#155547)

Consider IC when deciding if epilogue profitable for scalable vectors,
same as fixed-width vectors.

Author: hassnaaHamdi

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -4320,16 +4320,10 @@ bool LoopVectorizationCostModel::isEpilogueVectorizationProfitable(
   if (TTI.getMaxInterleaveFactor(VF) <= 1)
     return false;
 
-  // TODO: PR #108190 introduced a discrepancy between fixed-width and scalable
-  // VFs when deciding profitability.
-  // See related "TODO: extend to support scalable VFs." in
-  // selectEpilogueVectorizationFactor.
-  unsigned Multiplier = VF.isFixed() ? IC : 1;
   unsigned MinVFThreshold = EpilogueVectorizationMinVF.getNumOccurrences() > 0
                                 ? EpilogueVectorizationMinVF
                                 : TTI.getEpilogueVectorizationMinVF();
-  return estimateElementCount(VF * Multiplier, VScaleForTuning) >=
-         MinVFThreshold;
+  return estimateElementCount(VF * IC, VScaleForTuning) >= MinVFThreshold;
 }
 
 VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(