[llvm] TargetInstrInfo: make getOperandLatency return optional (NFC) (PR #73769)

[Francesco Petrogalli via llvm-commits]

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@@ -4070,11 +4064,11 @@ ARMBaseInstrInfo::getOperandLatency(const InstrItineraryData *ItinData,
     break;
   }
 
-  if (DefCycle == -1)
+  if (!DefCycle)
     // We can't seem to determine the result latency of the def, assume it's 2.
     DefCycle = 2;
 
-  int UseCycle = -1;
+  std::optional<unsigned> UseCycle = std::nullopt;
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fpetrogalli wrote:

Same:
```suggestion
  std::optional<unsigned> UseCycle;
```

https://github.com/llvm/llvm-project/pull/73769