Guard transaction-to-MLIR conversion when no parent aie.device exists

[Copilot]

convertTransactionOpsToMLIR assumed the builder insertion point was always nested under aie.device and unconditionally dereferenced the derived DeviceOp. This change makes that failure mode explicit and returns a clean LogicalResult failure with a diagnostic instead of crashing.

• What changed

  • Preserve the existing search for a parent DeviceOp from the current insertion point.
  • Add an explicit null check after the ancestor lookup.
  • Emit a diagnostic on the enclosing parent op when no aie.device is found.
  • Return failure() before any use of device.getLoc() / device.getBody().

• Behavioral impact

  • Valid call sites continue to behave unchanged.
  • Invalid insertion points now fail deterministically with a clear error instead of triggering a null dereference.

• Example

  Operation *parentOp = builder.getBlock()->getParentOp();
  DeviceOp device = llvm::dyn_cast<DeviceOp>(parentOp);
  if (!device)
    device = parentOp->getParentOfType<DeviceOp>();
  if (!device) {
    parentOp->emitError(
        "expected insertion point to be nested under an aie.device op");
    return failure();
  }

[fifield]

wrong branch