[llvm] [ConstantFolding] Add ilogb in isMathLibCallNoop (PR #122582)

[Yingwei Zheng via llvm-commits]

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@@ -3807,6 +3807,9 @@ bool llvm::isMathLibCallNoop(const CallBase *Call,
       case LibFunc_log10f:
         return Op.isNaN() || (!Op.isZero() && !Op.isNegative());
 
+      case LibFunc_ilogb:
+        return !Op.isNaN() && (!Op.isZero() && !Op.isInfinity());
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dtcxzyw wrote:

```suggestion
        return !Op.isNaN() && !Op.isZero() && !Op.isInfinity();
```

https://github.com/llvm/llvm-project/pull/122582