// 'ops_to_avoid' set, then the dependency walking is terminated.
  llvm::SetVector<Operation*> ops_to_process(*operations);
  llvm::SetVector<Operation*> new_ops;

  while (!ops_to_process.empty()) {
    for (Operation* op : ops_to_process) {
      if (predecessors) {
        for (Value operand : op->getOperands()) {
          // Stop at the block boundary.