<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/138647>138647</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [DebugInfo] RAUW updates debug value addresses using undefined local variables
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            question,
            debuginfo
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          Apochens
      </td>
    </tr>
</table>

<pre>
    When inspecting debug value updates in MemCpyOptimizer, I encountered a case: https://godbolt.org/z/WW98j8dPf. In short, I found a testcase that leads to a `dbg_value` referring to an undefined local variable after applying MemCpyOptimizer:

```llvm
    #dbg_value(ptr %test_array_b, !9, !DIExpression(), !16) ; refers to a local variable defined after it
 %test_array_b = alloca [31 x float], align 4, !dbg !17
    #dbg_value(ptr %test_array_b, !11, !DIExpression(), !17)
```

The code in MemCpyOptimizer leading to the IR is given in below:

https://github.com/llvm/llvm-project/blob/716b02d8c575afde7af1af13df145019659abca2/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp#L1668-L1669

And the code root for updating the metadata (i.e., `dbg_value`) is:

https://github.com/llvm/llvm-project/blob/41b76119ecc2b22546dc27ca51947304cf5aca28/llvm/lib/IR/Metadata.cpp#L588-L594

Is this an expected behavior? cc @OCHyams 
</pre>
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