[VPlan] Strip pred-block check in inLoopReductions (NFC) (#194086)

A VPInstruction will only have a mask if the block needs predication.

Author: artagnon

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -6997,14 +6997,8 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VPlanPtr Plan,
   ReversePostOrderTraversal<VPBlockShallowTraversalWrapper<VPBlockBase *>> RPOT(
       HeaderVPBB);
 
-  // Collect blocks that need predication for in-loop reduction recipes.
-  DenseSet<BasicBlock *> BlocksNeedingPredication;
-  for (BasicBlock *BB : OrigLoop->blocks())
-    if (CM.blockNeedsPredicationForAnyReason(BB))
-      BlocksNeedingPredication.insert(BB);
-
   RUN_VPLAN_PASS(VPlanTransforms::createInLoopReductionRecipes, *Plan,
-                 BlocksNeedingPredication, Range.Start);
+                 Range.Start);
 
   VPCostContext CostCtx(CM.TTI, *CM.TLI, *Plan, CM, Config.CostKind, CM.PSE,
                         OrigLoop);

llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp

@@ -993,9 +993,8 @@ bool VPlanTransforms::createHeaderPhiRecipes(
   return true;
 }
 
-void VPlanTransforms::createInLoopReductionRecipes(
-    VPlan &Plan, const DenseSet<BasicBlock *> &BlocksNeedingPredication,
-    ElementCount MinVF) {
+void VPlanTransforms::createInLoopReductionRecipes(VPlan &Plan,
+                                                   ElementCount MinVF) {
   VPTypeAnalysis TypeInfo(Plan);
   VPBasicBlock *Header = Plan.getVectorLoopRegion()->getEntryBasicBlock();
   SmallVector<VPRecipeBase *> ToDelete;
@@ -1124,13 +1123,9 @@ void VPlanTransforms::createInLoopReductionRecipes(
             "PreviousLink must be the operand other than VecOp");
       }
 
-      // Get block mask from CurrentLink, if it needs predication.
-      VPValue *CondOp = nullptr;
-      if (BlocksNeedingPredication.contains(CurrentLinkI->getParent()))
-        CondOp = cast<VPInstruction>(CurrentLink)->getMask();
-
       assert(PhiR->getVFScaleFactor() == 1 &&
              "inloop reductions must be unscaled");
+      VPValue *CondOp = cast<VPInstruction>(CurrentLink)->getMask();
       auto *RedRecipe = new VPReductionRecipe(
           Kind, FMFs, CurrentLinkI, PreviousLink, VecOp, CondOp,
           getReductionStyle(/*IsInLoop=*/true, PhiR->isOrdered(), 1),

llvm/lib/Transforms/Vectorize/VPlanTransforms.h

@@ -149,9 +149,7 @@ struct VPlanTransforms {
   /// Create VPReductionRecipes for in-loop reductions. This processes chains
   /// of operations contributing to in-loop reductions and creates appropriate
   /// VPReductionRecipe instances.
-  static void createInLoopReductionRecipes(
-      VPlan &Plan, const DenseSet<BasicBlock *> &BlocksNeedingPredication,
-      ElementCount MinVF);
+  static void createInLoopReductionRecipes(VPlan &Plan, ElementCount MinVF);
 
   /// Update \p Plan to account for all early exits. If \p Style is not
   /// NoUncountableExit, handles uncountable early exits and checks that all