llvm::SmallVector<mlir::OpAsmParser::UnresolvedOperand, 2>
      chain_and_allocator;
  if (parser.parseOperandList(chain_and_allocator,
                              /*requiredOperandCount=*/2,
                              mlir::OpAsmParser::Delimiter::Paren))
    return mlir::failure();

  auto &chain = chain_and_allocator[0];
  auto &allocator = chain_and_allocator[1];