[clang] [CIR] Upstream ArraySubscriptExpr for fixed size array (PR #134536)

[Erich Keane via cfe-commits]

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@@ -232,6 +233,161 @@ LValue CIRGenFunction::emitUnaryOpLValue(const UnaryOperator *e) {
   llvm_unreachable("Unknown unary operator kind!");
 }
 
+/// If the specified expr is a simple decay from an array to pointer,
+/// return the array subexpression.
+/// FIXME: this could be abstracted into a commeon AST helper.
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erichkeane wrote:

```suggestion
/// FIXME: this could be abstracted into a common AST helper.
```

https://github.com/llvm/llvm-project/pull/134536