UVM basics --------- UVM Report Mechanism Analysis

The information reporting mechanism in UVM is relatively simple, and the function is mainly divided into two parts:
First, the Information Report redundancy level of component is controlled by ID, and different behavior control is performed for each redundancy level. This part of work is mainly implemented by uvm_report_hander: The main involved methods include get_report_verbosity_level (severity, ID)/get_report_action (severity, ID) = uvm_action '(uvm_no_action) the second is to format the message output. uvm_report_server is used to implement message_compose.
We analyze the execution of a 'vm _ error macro, 'vm _ error ("driver", "The Config object is null ")
This is a UVM macro called in TB. It mainly receives two parameter IDs and the MSG to be printed. This macro is defined in uvm_message_defines.svh and is defined as follows:
140 'define uvm_error (ID, MSG) \ 141 begin \ 142 If (uvm_report_enabled (uvm_none, uvm_error, ID) \ 143 uvm_report_error (ID, MSG, uvm_none, 'uvm _ file, 'uvm _ line); \ 144 end
The uvm_report_enabled function is called to check whether the message allows output. This function has two versions. If the uvm_error macro is called in a component, the component function is used, which is defined in uvm_report_object: 447 function int uvm_report_enabled (INT verbosity, 448 uvm_severity severity = uvm_info, string id = ""); 449 If (if (severity, ID) <verbosity | // check the corresponding severity, whether the verbosity (redundancy level) of the ID is greater than the verbosity450 get_report_action (severity, ID) = uvm_action '(uvm_no_action) that can be output. // check the corresponding severity, whether the ID action is uvm_no_action451 return 0; 452 else 453 return 1; 454 if the endfunction uses this macro in a sequence or a class derived from uvm_object, the global function 115 function bit uvm_report_enabled (INT verbosity, 116 uvm_severity severity = uvm_info, string id = ""); 117 uvm_root top; 118 Top = uvm_root :: get (); 119 return top. uvm_report_enabled (verbosity, severity, ID); 120 endfunction
Get_report_verbosity_level is defined as follows: m_rh is a uvm_report_handler type variable, which will be instantiated when each component is instantiated, that is, each component corresponds to a m_rh, this variable is used to record some report information of this component, such as whether the report redundancy level (verbosity_lever) is set for this component separately ). The get_report_verbosity_level function calls the get_verbosity_level function of uvm_report_handler.
81 class uvm_report_object extends uvm_object; 82 83 uvm_report_handler m_rh ;... 90 function new (string name = ""); 91 super. New (name); 92 m_rh = new (); 93 endfunction... 413 function int get_report_verbosity_level (uvm_severity severity = uvm_info, string id = ""); 414 return m_rh.get_verbosity_level (severity, ID); 415 endfunction... 539 endclas
The following is a brief analysis of the get_verbosity_level function used in uvm_report_handler. We can learn some Array Control Methods: 55 class uvm_report_handler ;... 236 function int get_verbosity_level (uvm_severity severity = uvm_info, string id = ""); 237 238 239 rows array; If (if (severity) Begin // first judge severity_id_verbosities (Union array, whether the index is severity) has a 240 array = severity_id_verbosities [severity] record corresponding to serverity; // The Union array returns a uvm_id_verbosities_array, which is an instance of uvm_pool, 241 if (array. exists (ID) Begin // This uvm_id_v The index of erbosities_array is the corresponding message_id, And the content is the redundant integer 242 return array of the message_id. get (ID); // Where is the severity_id_verbosities written ?? 243 end 244 end 245 246 if (id_verbosities.exists (ID) Begin // id_verbosities is a sort type variable 247 return id_verbosities.get (ID); // The index is the corresponding message_id, the content is the same as the redundant integer of message_id 248 end //. When will this id_verbosities be written ?? 249 250 return m_max_verbosity_level; 251 252 endfunction... 622 endclass: uvm_report_handle

The processing of uvm_action and file handle is similar to get_verbosity_level. We will not analyze them here. Now we analyze the two problems mentioned in the code analysis above:
1. Where is the severity_id_verbosities written? We will analyze the uvm_report_handler Code directly, because as mentioned above, handler is used to implement and manage this part of work:
Function void set_severity_id_verbosity (uvm_severity severity, string ID, int verbosity); If (! Severity_id_verbosities.exists (severity) severity_id_verbosities [severity] = new; severity_id_verbosities [severity]. Add (ID, verbosity); endfunction
2. When will id_verbosities be written? Function void set_id_verbosity (input string ID, input int verbosity); id_verbosities.add (ID, verbosity); endfunction
The code above shows that set_severity_id_verbosity has a higher priority than set_id_verbosity.
As we mentioned earlier, the output of message formatting is mainly implemented by uvm_report_server. Therefore, after uvm_report_error is passed, the report function in uvm_report_server will be called, here we need to mention that uvm_report_server is a single instance. Here we reiterate the relationship between several classes in the uvm_report mechanism. The relationship between Report-object and report_handler is one-to-one, of course, multiple report_objects can correspond to one report_handler (set_report_handler ). the handler-to-server relationship is many-to-one.
243 virtual function void report (244 uvm_severity severity, 245 string name, 246 string ID, 247 string message, 248 int verbosity_level, 249 string filename, 250 int line, 251 uvm_report_object client 252 ); 253 string m; 254 uvm_action A; 255 uvm_file F; 256 bit report_ OK; 257 uvm_report_handler RH; 258 259 RH = client. get_report_handler (); // get the instance pointer of uvm_component again to perform uvm_report_enabled check again and get file_handle260 261/Filter Based on verbosity level 262 In uvm_report_handler.
273 F = RH. get_file_handle (severity, ID); 274 275 // The hooks can do additional filtering. if the hook function 276 // return 1 then continue processing the report. if the hook 277 // returns 0 Then skip processing the report. 278 279 if (A & uvm_call_hook) 280 report_ OK = RH. run_hooks (client, severity, ID, 281 message, verbosity_level, filename, line); // call the run_hooks function to confirm whether to print the information again. Define in ort_handler and call the report_info_hook/hooks/report_error_hook/report_fatal_hook function defined in uvm_report_object. You can reload these hooks when inheriting uvm_component. In this way, message control is implemented.
282 else 283 report_ OK = 1;
285 If (report_ OK) 286 report_ OK = uvm_report_catcher: process_all_report_catchers (// This Is A uvm_callback class. Its main use is to control the information to be printed again before the actual information is printed, every uvm_catcher must implement a catch function! 287 this, client, severity, name, ID, message, 288 verbosity_level, A, filename, line); 289 290 if (report_ OK) Begin 291 M = compose_message (severity, name, ID, message, filename, line); 292 process_report (severity, name, ID, message, A, F, filename,


This is the process_report_catcher function in uvm_catcher:
Local function int process_report_catcher (); action_e Act; Act = This. catch (); If (Act = unknown_action) This. uvm_report_error ("rptcthr", {"uvm_report_this.catch () in Catcher instance", this. get_name (), "Must return throw or caught"}, uvm_none, 'vm _ file, 'uvm _ line); If (m_debug_flags & do_not_modify) Begin m_modified_severity = m_orig_severity; m_modified_id = m_orig_id; m_modified_verbosity = M _ Orig_verbosity; m_modified_action = m_orig_action; m_modified_message = m_orig_message; end if (Act = caught &&! (M_debug_flags & do_not_catch) Begin return 0; end return 1; endfunction






From Weizhi note (wiz)