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 = ;
 
   // 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 > ) begin
     test_name = test_names[];
     testname_plusarg = ;
   end
 
   // If multiple, provided the warning giving the number, which one will be
   // used and the complete list.
   if (test_name_count > ) begin
     string test_list;
     string sep;
     for (int i = ; i < test_names.size(); i++) begin
       if (i != )
         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 = ;
   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);
       #; // 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() == ) 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
   #; // let the phase runner start
 
   wait (m_phase_all_done == );
 
   // 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/