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

[Sam Tebbs via llvm-commits]

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@@ -2866,6 +2881,19 @@ bool LoopVectorizationCostModel::isPredicatedInst(Instruction *I) const {
   }
 }
 
+unsigned LoopVectorizationCostModel::getPredBlockCostDivisor(
+    TargetTransformInfo::TargetCostKind CostKind, const BasicBlock *BB) const {
+  if (CostKind == TTI::TCK_CodeSize)
+    return 1;
+
+  uint64_t HeaderFreq = BFI->getBlockFreq(TheLoop->getHeader()).getFrequency();
+  uint64_t BBFreq = BFI->getBlockFreq(BB).getFrequency();
+  assert(HeaderFreq >= BBFreq &&
+         "Header has smaller block freq than dominated BB?");
+  return BFI->getBlockFreq(TheLoop->getHeader()).getFrequency() /
+         BFI->getBlockFreq(BB).getFrequency();
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SamTebbs33 wrote:

You already have `HeaderFreq` and `BBFreq` so I don't think you need to call `getBlockFreq` again when returning.

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