[clang] [llvm] [PowerPC] Fix codegen for transparent_union function params (PR #101738)

[Hubert Tong via cfe-commits]

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@@ -65,6 +65,10 @@ CGCXXABI::RecordArgABI getRecordArgABI(QualType T, CGCXXABI &CXXABI);
 bool classifyReturnType(const CGCXXABI &CXXABI, CGFunctionInfo &FI,
                         const ABIInfo &Info);
 
+// For transparent union types, return the type of the first element.
+// Set reference TU to true if Ty given was a transparent union.
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hubert-reinterpretcast wrote:

```suggestion
// Set TU to true if Ty given was a transparent union and to false otherwise.
```

https://github.com/llvm/llvm-project/pull/101738