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

[Luke Lau via llvm-commits]

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@@ -65,7 +65,7 @@ for.body:
   %r = phi i64 [ 0, %entry ], [ %var6, %for.inc ]
   %var0 = getelementptr inbounds i64, ptr %a, i64 %i
   %var2 = load i64, ptr %var0, align 4
-  %cond0 = icmp sgt i64 %var2, 0
+  %cond0 = icmp sgt i64 %var2, 1
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lukel97 wrote:

This constant was changed to keep the old branch probability the same and keep the block scalarized, since with BFI `icmp sgt %x, 0` is predicted to be slightly > 50%. 

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