[llvm] [VPlan] Use BlockFrequencyInfo in getPredBlockCostDivisor (PR #158690)

[Luke Lau via llvm-commits]

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@@ -1239,22 +1241,9 @@ class LoopVectorizationCostModel {
   /// only contribute 1/X of its cost to the total cost calculation, but when
   /// optimizing for code size it will just be 1 as code size costs don't depend
   /// on execution probabilities.
-  ///
-  /// TODO: We should use actual block probability here, if available.
-  /// Currently, we always assume predicated blocks have a 50% chance of
-  /// executing, apart from blocks that are only predicated due to tail folding.
   inline unsigned
   getPredBlockCostDivisor(TargetTransformInfo::TargetCostKind CostKind,
-                          BasicBlock *BB) const {
-    // If a block wasn't originally predicated but was predicated due to
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lukel97 wrote:

I've moved part of this explanation for tail folded loops back into the definition in 6ee702b1052b

https://github.com/llvm/llvm-project/pull/158690