[llvm] [LV][VPlan] Implement VPlan-based cost for exit condition. (PR #125640)

[David Sherwood via llvm-commits]

================
@@ -823,6 +823,29 @@ bool VPInstruction::onlyFirstPartUsed(const VPValue *Op) const {
   llvm_unreachable("switch should return");
 }
 
+InstructionCost VPInstruction::computeCost(ElementCount VF,
+                                           VPCostContext &Ctx) const {
+  Type *ValTy = Ctx.Types.inferScalarType(getOperand(0));
+
+  switch (getOpcode()) {
+  case VPInstruction::BranchOnCount: {
+    // BranchOnCount will genearte icmp_eq + br instructions and the
----------------
david-arm wrote:

nit: I think that should be `generate` instead of `genearte`

https://github.com/llvm/llvm-project/pull/125640