[llvm] [LV] Skip sentinel value for FindLastIV reductions when start value is provably less than IV start. (PR #141788)

[Ramkumar Ramachandra via llvm-commits]

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@@ -700,18 +707,18 @@ RecurrenceDescriptor::isFindLastIVPattern(Loop *TheLoop, PHINode *OrigPhi,
                                      m_Value(NonRdxPhi)))))
     return InstDesc(false, I);
 
-  auto IsIncreasingLoopInduction = [&](Value *V) {
+  auto IsIncreasingLoopInduction = [&](Value *V) -> std::pair<bool, Value *> {
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artagnon wrote:

std::optional<Value *>?

https://github.com/llvm/llvm-project/pull/141788