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

[Luke Lau via llvm-commits]

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@@ -105,7 +105,7 @@ loop.header:
   %gep.src = getelementptr inbounds i64, ptr %src, i64 %iv
   %l = load i64, ptr %gep.src, align 1
   %t = trunc i64 %l to i1
-  br i1 %t, label %exit.0, label %loop.latch
+  br i1 %t, label %exit.0, label %loop.latch, !prof !0
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lukel97 wrote:

Added to retain the old branch probability. With BFI, the probability of exit.0 being taken is computed as 3% (why that is, I'm not sure) and the IV increment isn't discounted in the VF=1 plan. 

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