[clang] [CIR] Add support for array cleanups (PR #150499)

[Henrich Lauko via cfe-commits]

================
@@ -658,10 +693,38 @@ void CIRGenFunction::emitNullabilityCheck(LValue lhs, mlir::Value rhs,
 ///   elements
 void CIRGenFunction::emitDestroy(Address addr, QualType type,
                                  Destroyer *destroyer) {
-  if (getContext().getAsArrayType(type))
-    cgm.errorNYI("emitDestroy: array type");
+  const ArrayType *arrayType = getContext().getAsArrayType(type);
+  if (!arrayType)
+    return destroyer(*this, addr, type);
+
+  mlir::Value length = emitArrayLength(arrayType, type, addr);
+
+  CharUnits elementAlign = addr.getAlignment().alignmentOfArrayElement(
+      getContext().getTypeSizeInChars(type));
+
+  // Normally we have to check whether the array is zero-length.
+  bool checkZeroLength = true;
+
+  // But if the array length is constant, we can suppress that.
+  auto constantCount = dyn_cast<cir::ConstantOp>(length.getDefiningOp());
----------------
xlauko wrote:

```suggestion
  auto constantCount = length.getDefiningOp<cir::ConstantOp>();
```

https://github.com/llvm/llvm-project/pull/150499