How does set_inst_override_by_type work?

UVM
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1

Hi,

Can somebody help me to understand how factory.set_inst_override_by_type work when the override class contains an original class object?

A original_type
B override_type, which contains A object

When use B override A, should I expect the A_obj also get override?
I tried it on irun, it gets stuck?

module tb;
import uvm_pkg::*; 
`include "uvm_macros.svh"
   
class A extends uvm_object;
   rand bit[7:0] pkt_len;
   `uvm_object_utils_begin(A)
      `uvm_field_int(pkt_len, UVM_ALL_ON)
   `uvm_object_utils_end
   
   function new(string name="A");
      super.new(name);
   endfunction // new
endclass // A

typedef enum {ETH, IPV4} pkt_type_e;

class B extends A;
   rand  pkt_type_e pkt_type;
   A A_obj;
   
   `uvm_object_utils_begin(B)
      `uvm_field_enum(pkt_type_e, pkt_type, UVM_ALL_ON)
      `uvm_field_object(A_obj, UVM_ALL_ON)
   `uvm_object_utils_end
   
   function new(string name="B");
      super.new(name);
      A_obj = A::type_id::create("A");
   endfunction // new
endclass // B

class test1 extends uvm_test;
    A A1;
    B B1;

   `uvm_component_utils(test1)
   function new(string name="test1", uvm_component parent);
      super.new(name, parent);
   endfunction // new

   function void build_phase(uvm_phase phase);
      super.build_phase(phase);

      A::type_id::set_inst_override(B::get_type(), "*");
      A1 = A::type_id::create("A1");
      A1.print();

   endfunction // build_phase
endclass // test1
   
initial run_test("test1");
endmodule
2

In reply to mlsxdx:

You are getting into an infinite loop because you are using the wildcard “*” as the instance name, which is the same as overriding all A class types with B. Then you are creating a B object which contains a B object, which contains a B object.

With class derived from uvm_object, the instance name is just the simple name of the object, so if you change your override to

      A::type_id::set_inst_override(B::get_type(), "A1");

It should work that way you expect it to.

3

In reply to dave_59:

Thanks Dave. It works as you said.