run_test() 验证平台的入口

Run,just run!    ——阿甘正传

 

一个简单的例子：

module tb_top;
    dut u_dut ();

    initial begin
        run_test();
    end

    config_db #()::set();
    
endmoudle

UVM验证平台从仿真器执行时，开始执行initial中的run_test(); 这时首先去uvm_global.svh中查找run_test();

// Title: Globals

//------------------------------------------------------------------------------
//
// Group: Simulation Control
//
//------------------------------------------------------------------------------

// Task: run_test
//
// Convenience function for uvm_top.run_test(). See <uvm_root> for more
// information.

task run_test (string test_name="");
  uvm_root top;
  uvm_coreservice_t cs;
  cs = uvm_coreservice_t::get();
  top = cs.get_root();
  top.run_test(test_name);
endtask

全局的run_test() 又调用uvm_root.svh的run_test（）

//----------------------------------------------------------------------------
  // Group: Simulation Control
  //----------------------------------------------------------------------------


  // Task: run_test
  //
  // Phases all components through all registered phases. If the optional
  // test_name argument is provided, or if a command-line plusarg,
  // +UVM_TESTNAME=TEST_NAME, is found, then the specified component is created
  // just prior to phasing. The test may contain new verification components or
  // the entire testbench, in which case the test and testbench can be chosen from
  // the command line without forcing recompilation. If the global (package)
  // variable, finish_on_completion, is set, then $finish is called after
  // phasing completes.

  extern virtual task run_test (string test_name="");


// run_test
// --------

task uvm_root::run_test(string test_name="");

  uvm_report_server l_rs;
  uvm_coreservice_t cs = uvm_coreservice_t::get();                                                     
  uvm_factory factory=cs.get_factory();
  bit testname_plusarg;
  int test_name_count;
  string test_names[$];
  string msg;
  uvm_component uvm_test_top;

  process phase_runner_proc; // store thread forked below for final cleanup

  testname_plusarg = 0;

  // Set up the process that decouples the thread that drops objections from
  // the process that processes drop/all_dropped objections. Thus, if the
  // original calling thread (the "dropper") gets killed, it does not affect
  // drain-time and propagation of the drop up the hierarchy.
  // Needs to be done in run_test since it needs to be in an
  // initial block to fork a process.
  uvm_objection::m_init_objections();

`ifndef UVM_NO_DPI

  // Retrieve the test names provided on the command line.  Command line
  // overrides the argument.
  test_name_count = clp.get_arg_values("+UVM_TESTNAME=", test_names);

  // If at least one, use first in queue.
  if (test_name_count > 0) begin
    test_name = test_names[0];
    testname_plusarg = 1;
  end

  // If multiple, provided the warning giving the number, which one will be
  // used and the complete list.
  if (test_name_count > 1) begin
    string test_list;
    string sep;
    for (int i = 0; i < test_names.size(); i++) begin
      if (i != 0)
        sep = ", ";
      test_list = {test_list, sep, test_names[i]};
    end
    uvm_report_warning("MULTTST", 
      $sformatf("Multiple (%0d) +UVM_TESTNAME arguments provided on the command line.  '%s' will be used.  Provided list: %s.", test_name_count, test_name, test_list), UVM_NONE);
  end

`else

     // plusarg overrides argument
  if ($value$plusargs("UVM_TESTNAME=%s", test_name)) begin
    `uvm_info("NO_DPI_TSTNAME", "UVM_NO_DPI defined--getting UVM_TESTNAME directly, without DPI", UVM_NONE)
    testname_plusarg = 1;
  end

`endif

  // if test now defined, create it using common factory
  if (test_name != "") begin
      uvm_coreservice_t cs = uvm_coreservice_t::get();                                                     
      uvm_factory factory=cs.get_factory();
      
    if(m_children.exists("uvm_test_top")) begin
      uvm_report_fatal("TTINST",
          "An uvm_test_top already exists via a previous call to run_test", UVM_NONE);
      #0; // forces shutdown because $finish is forked
    end
    $cast(uvm_test_top, factory.create_component_by_name(test_name,
          "", "uvm_test_top", null));

    if (uvm_test_top == null) begin
      msg = testname_plusarg ? {"command line +UVM_TESTNAME=",test_name} : 
                               {"call to run_test(",test_name,")"};
      uvm_report_fatal("INVTST",
          {"Requested test from ",msg, " not found." }, UVM_NONE);
    end
  end

  if (m_children.num() == 0) begin
    uvm_report_fatal("NOCOMP",
          {"No components instantiated. You must either instantiate",
           " at least one component before calling run_test or use",
           " run_test to do so. To run a test using run_test,",
           " use +UVM_TESTNAME or supply the test name in",
           " the argument to run_test(). Exiting simulation."}, UVM_NONE);
    return;
  end

  begin
      if(test_name=="") 
          uvm_report_info("RNTST", "Running test ...", UVM_LOW); 
      else if (test_name == uvm_test_top.get_type_name())
          uvm_report_info("RNTST", {"Running test ",test_name,"..."}, UVM_LOW); 
      else
          uvm_report_info("RNTST", {"Running test ",uvm_test_top.get_type_name()," (via factory override for test \"",test_name,"\")..."}, UVM_LOW);
  end
  
  // phase runner, isolated from calling process
  fork begin
    // spawn the phase runner task
    phase_runner_proc = process::self();
    uvm_phase::m_run_phases();
  end
  join_none
  #0; // let the phase runner start
  
  wait (m_phase_all_done == 1);
  
  // clean up after ourselves
  phase_runner_proc.kill();

  l_rs = uvm_report_server::get_server();
  l_rs.report_summarize();

  if (finish_on_completion)
    $finish;

endtask

在该run_test 实现中根据有没有DPI调用phase.这样在运行仿真命令时通过simcmd +UVM_TESTNAME=my_case 来执行该case,这样整个系统就被调用了起来。这样做有什么好处？它根据传入的字符串或者从运行参数+UVM_TESTNAME="test_name"读取字符串来生成uvm_test对象, 并运行这个对象的全部phase函数来执行一次测试用例的运行,很方便实现regression。

 

参考文献：

1 Just Run.https://movie.douban.com/review/5526733/