[llvm] [VPlan] First step towards VPlan cost modeling. (PR #67934)

[via llvm-commits]

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@@ -699,6 +700,14 @@ class VPLiveOut : public VPUser {
 #endif
 };
 
+struct VPCostContext {
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ayalz wrote:

Document what this is for.

https://github.com/llvm/llvm-project/pull/67934