[llvm] [IR][NFC] Switch to use `LifetimeIntrinsic` (PR #125528)

[Nikita Popov via llvm-commits]

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@@ -535,13 +535,10 @@ void CodeExtractor::findAllocas(const CodeExtractorAnalysisCache &CEAC,
 
       Instruction *Bitcast = cast<Instruction>(U);
       for (User *BU : Bitcast->users()) {
-        IntrinsicInst *IntrInst = dyn_cast<IntrinsicInst>(BU);
+        IntrinsicInst *IntrInst = dyn_cast<LifetimeIntrinsic>(BU);
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nikic wrote:

```suggestion
        auto *IntrInst = dyn_cast<LifetimeIntrinsic>(BU);
```

https://github.com/llvm/llvm-project/pull/125528