MLIR code slide

//遍历一个function
func.walk([&](Operation *op) {
  size_t nUser =
      llvm::count_if(op->getUsers(), [](auto *) { return true; });
  unresolvedUsers[op] = nUser;
});

//返乡遍历operand
for (auto opr : llvm::reverse(op->getOperands())) {
  if (auto def = opr.getDefiningOp<StcGoatInterface>()) {
    if (--unresolvedUsers[def] == 0) {
      todoList.push_front(def);
    }
  }
}
//OpBuilder使用Context初始化：
OpBuilder builder(op->getContext());