[llvm] [LV] Add epilogue minimum iteration check in VPlan as well. (PR #189372)

[Ramkumar Ramachandra via llvm-commits]

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@@ -9817,18 +9665,51 @@ bool LoopVectorizePass::processLoop(Loop *L) {
         preparePlanForMainVectorLoop(*BestMainPlan, BestEpiPlan);
     EpilogueLoopVectorizationInfo EPI(VF.Width, IC, EpilogueVF.Width, 1,
                                       BestEpiPlan);
+
+    // Add minimum iteration check for the epilogue plan, followed by runtime
+    // checks for the main plan.
+    LVP.addMinimumIterationCheck(*BestMainPlan, EPI.EpilogueVF, EPI.EpilogueUF,
+                                 ElementCount::getFixed(0));
+    bool HasBranchWeights =
+        hasBranchWeightMD(*L->getLoopLatch()->getTerminator());
+    LVP.attachRuntimeChecks(*BestMainPlan, Checks, HasBranchWeights);
+    LVP.addIterationCountCheckBlock(*BestMainPlan, EPI.MainLoopVF,
+                                    EPI.MainLoopUF);
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artagnon wrote:

Could pass the BranchWeights here directly, simplifying and possibly eliminating LoopVectorizationPlanner::addIterationCountCheckBlock altogether?

https://github.com/llvm/llvm-project/pull/189372