llvm::DenseSet<BlockArgument> options;
    for (Block *block : blockArg.getOwner()->getPredecessors()) {
      if (!block->empty()) {
        Operation *back = &block->back();
        if (BranchOpInterface branchOp = dyn_cast<BranchOpInterface>(back)) {
          for (int i = 0; i < branchOp->getNumSuccessors(); i++) {
            if (branchOp->getSuccessor(i) != blockArg.getOwner()) continue;