[clang] [CIR] Upstream DynamicCastOp (PR #161734)

[Henrich Lauko via cfe-commits]

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@@ -601,6 +601,60 @@ def CIR_VTableAttr : CIR_Attr<"VTable", "vtable", [TypedAttrInterface]> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// DynamicCastInfoAttr
+//===----------------------------------------------------------------------===//
+
+def CIR_DynamicCastInfoAttr : CIR_Attr<"DynamicCastInfo", "dyn_cast_info"> {
+  let summary = "ABI specific information about a dynamic cast";
+  let description = [{
+    Provide ABI specific information about a dynamic cast operation.
+
+    The `srcRtti` and the `destRtti` parameters give the RTTI of the source
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xlauko wrote:

No strong opinion here, I see pros/cons for both. I think snake_case is more conventional for tablegen primitives. PErsonaly I find it more readable, though this sometimes leads to weird names as it is used to generate camelCase in C++. (e.g. `openMP_xxx`). Advantage of having camelCase is to have same name is in C++ and easier code grepping and orientation.

https://github.com/llvm/llvm-project/pull/161734