[llvm] [VPlan] Move predication to VPlanTransform (NFC). (PR #128420)

[via llvm-commits]

================
@@ -9442,43 +9232,32 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range,
   }
 
   // ---------------------------------------------------------------------------
-  // Construct recipes for the instructions in the loop
+  // Predicate and linearize the top-level loop region.
   // ---------------------------------------------------------------------------
+  DenseMap<VPBasicBlock *, VPValue *> BlockMaskCache;
+  VPlanTransforms::predicateAndLinearize(*Plan, CM.foldTailByMasking(),
+                                         BlockMaskCache);
 
-  VPRegionBlock *LoopRegion = Plan->getVectorLoopRegion();
-  VPBasicBlock *HeaderVPBB = LoopRegion->getEntryBasicBlock();
-  BasicBlock *HeaderBB = OrigLoop->getHeader();
-  bool NeedsMasks =
-      CM.foldTailByMasking() ||
-      any_of(OrigLoop->blocks(), [this, HeaderBB](BasicBlock *BB) {
-        bool NeedsBlends = BB != HeaderBB && !BB->phis().empty();
-        return Legal->blockNeedsPredication(BB) || NeedsBlends;
-      });
-
+  // ---------------------------------------------------------------------------
+  // Construct recipes for the instructions in the loop
----------------
ayalz wrote:

```suggestion
  // Construct wide recipes and apply predication for original scalar VPInstructions in the loop.
```
?

Follow-up: outline this into a VPlanTransform?

https://github.com/llvm/llvm-project/pull/128420