[llvm] [LV] Mark functions in legacy cost model const (NFC) (PR #216282)

[Florian Hahn via llvm-commits]

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@@ -2496,8 +2488,8 @@ uint64_t LoopVectorizationCostModel::getPredBlockCostDivisor(
     return 1;
 
   uint64_t HeaderFreq =
-      getBFI().getBlockFreq(TheLoop->getHeader()).getFrequency();
-  uint64_t BBFreq = getBFI().getBlockFreq(BB).getFrequency();
+      GetBFI().getBlockFreq(TheLoop->getHeader()).getFrequency();
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fhahn wrote:

>   /// Returns the BlockFrequencyInfo for the function if cached, otherwise
>  /// fetches it via GetBFI. Avoids an indirect call to the std::function.

I think the comment still applies, we need to go through `std::function` on each call?

https://github.com/llvm/llvm-project/pull/216282