[llvm] [VPlan] Manage Sentinel value for FindLastIV in VPlan. (PR #142291)

[via llvm-commits]

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@@ -7266,9 +7266,11 @@ static void fixReductionScalarResumeWhenVectorizingEpilog(
     using namespace llvm::PatternMatch;
     Value *Cmp, *OrigResumeV, *CmpOp;
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ayalz wrote:

`Value *Sentinel = ‏EpiRedResult->getOperand(2)->getLiveInIRValue();`

Perhaps worth a `Value *vputils::getSentinel(VPInstruction*)`?

https://github.com/llvm/llvm-project/pull/142291