[llvm] [VPlan] Sink retrieving legacy costs to more specific computeCost impls. (PR #109708)

[via llvm-commits]

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@@ -2156,6 +2158,11 @@ void VPBranchOnMaskRecipe::execute(VPTransformState &State) {
   ReplaceInstWithInst(CurrentTerminator, CondBr);
 }
 
+InstructionCost VPBranchOnMaskRecipe::computeCost(ElementCount VF,
+                                                  VPCostContext &Ctx) const {
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ayalz wrote:

Some explanation for treating this branch as free.

https://github.com/llvm/llvm-project/pull/109708