[llvm] [VPlan] Give zero-weight edges minimum probability. (PR #226150)

[David Sherwood via llvm-commits]

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@@ -67,6 +67,67 @@ exit:
   ret void
 }
 
+define void @single_pred_zero_weight(ptr noalias %a, ptr noalias %b, ptr noalias %idx) {
+; %if.then is only entered via an edge with zero branch weight. BFI treats the
+; edge as cold, not as never taken, and gives %if.then the minimum non-zero
+; frequency of 2^-31.
+;
+;   %loop       1 =        1
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david-arm wrote:

I'm not sure what the "1 = 1" comment here means?

https://github.com/llvm/llvm-project/pull/226150