[llvm] [VPlan] Add new VPInstruction ocpode for header mask. (PR #89603)

[via llvm-commits]

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@@ -8555,6 +8548,7 @@ void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
       // TODO: try to put it close to addActiveLaneMask().
       if (CM.foldTailWithEVL())
         VPlanTransforms::addExplicitVectorLength(*Plan);
+      VPlanTransforms::lowerRecipes(*Plan);
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ayalz wrote:

(TODO) The three passes that lower the header mask (addActiveLaneMask, addExplicitVectorLength, lowerRecipes) should arguably be applied together, depending on tail folding style, inside VPlanTransforms::optimize().

https://github.com/llvm/llvm-project/pull/89603