[clang] [CIR] Upstream Re-Throw with no return (PR #154994)

[Andy Kaylor via cfe-commits]

================
@@ -2646,6 +2646,24 @@ ParseResult cir::InlineAsmOp::parse(OpAsmParser &parser,
   return mlir::success();
 }
 
+//===----------------------------------------------------------------------===//
+// ThrowOp
+//===----------------------------------------------------------------------===//
+
+mlir::LogicalResult cir::ThrowOp::verify() {
+  // For the no-rethrow version, it must have at least the exception pointer.
+  if (rethrows())
+    return success();
+
+  if (getNumOperands() == 1) {
----------------
andykaylor wrote:

```suggestion
  if (getNumOperands() != 0) {
```
I don't think this will ever be 1. In fact, maybe we should check for that. We need at least type info and an exception pointer if this isn't a rethrow.

When RTTI is implemented, it might be good to add a check to verify that `type_info` references valid type info, and perhaps also that `dtor`, if present, references a destructor.

https://github.com/llvm/llvm-project/pull/154994