[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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@@ -376,6 +378,10 @@ bool RecurrenceDescriptor::AddReductionVar(
       ExactFPMathInst = ExactFPMathInst == nullptr
                             ? ReduxDesc.getExactFPMathInst()
                             : ExactFPMathInst;
+      if (auto *Sentinel = ReduxDesc.getSentinelValue()) {
+        assert(!SentinelValue && "Sentinel value can only be assigned once");
+        SentinelValue = Sentinel;
+      }
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artagnon wrote:

Move to end of block?

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