[llvm] [VPlan] Delay adding canonical IV increment. (PR #82270)

[via llvm-commits]

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@@ -10272,7 +10271,7 @@ preparePlanForEpilogueVectorLoop(VPlan &Plan, Loop *L,
                              isa<VPScalarCastRecipe>(U) ||
                              isa<VPDerivedIVRecipe>(U) ||
                              cast<VPInstruction>(U)->getOpcode() ==
-                                 Instruction::Add;
+                                 VPInstruction::BranchOnCount;
                     }) &&
              "the canonical IV should only be used by its increment or "
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ayalz wrote:

```suggestion
             "the canonical IV should only be used by its BranchOnCount or "
```

https://github.com/llvm/llvm-project/pull/82270