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What if inheritance occurs for a class with an embedded covergroup?

Jeff000

As the code shown below, what is the relationship between those two covergroup named cg?


  class A;
     int a;
     
     covergroup cg @(clk);
        option.per_instance = 1;
        v_a: coverpoint a
          iff(reset){}
        
     endgroup // cg
     
  endclass // A

   class B extends A;
     int b;
      
     covergroup cg @(clk);
        option.per_instance = 1;
        v_b: coverpoint b
          iff(reset){}
        
     endgroup // cg

   endclass // B
Parents

  • Thanks TAM1 for your kind reply.

    What I expect is to have A and B take their own covergroup, i.e. A with covergroup defined in class A while B has covergroup defined in class B. I've "new" both for A and B as below and assign distinct name for each by calling cg.set_inst_name(), which I think will have the same effect as cg.option.name = "".

    
reg clk=0;
always #5 clk = !clk;

class A;
    bit[1:0] a;

    covergroup cg @(clk);
    option.per_instance = 1;
    v_a: coverpoint a
        iff(reset){}
    endgroup // cg

function new;
    cg = new;
    cg.option.name = "A_group"; // optional
endfunction

endclass // A

class B extends A;
    bit[1:0] b;

    covergroup cg @(clk);
    option.per_instance = 1;
    v_b: coverpoint b
        iff(reset){}
    endgroup // cg

    function new;
    super.new;  // optional
    cg = new;
    cg.option.name = "B_group"; // optional
    endfunction 
endclass // B

A c_a;
B c_b;
initial
begin
    c_a = new;
    c_b = new;
    c_a.a = 1;
    c_b.a = 2;
    c_b.b = 3;
    #10 $finish;
end

    As the instance-based report shows, the A's covergroup still exists in B's covergroup (even without calling super.new in B), is there any way to ignore cov_A in cov_B?

    Thanks.

    
Name         Average, Covered Grade Line Source Code
c_a.A_group  25.00%, 25.00% (1/4)   299  covergroup cg (@clk);
|--v_a       25.00% (1/4)           301  coverpoint a
| --auto[0]  0.00% (0/1)            301  coverpoint a
| |--auto[1] 100.00% (39/1)         301  coverpoint a
| |--auto[2] 0.00% (0/1)            301  coverpoint a
| |--auto[3] 0.00% (0/1)            301  coverpoint a
c_b.A_group  25.00%, 25.00% (1/4)   299  covergroup cg (@clk);
| - -v_a     25.00% (1/4)           301  coverpoint a
| |--auto[0] 0.00% (0/1)            301  coverpoint a
| |--auto[1] 0.00% (0/1)            301  coverpoint a
| |--auto[2]  100.00% (39/1)         301  coverpoint a
| |--auto[3] 0.00% (0/1)            301  coverpoint a
c_b.B_group  25.00%, 25.00% (1/4)   315  covergroup cg (@clk);
|--v_b       25.00% (1/4)           317  coverpoint b
| |--auto[0] 0.00% (0/1)            317  coverpoint b
| |--auto[1] 0.00% (0/1)            317  coverpoint b
| |--auto[2] 0.00% (0/1)            317  coverpoint b
| |--auto[3] 100.00% (39/1)         317  coverpoint b
Reply

  • Thanks TAM1 for your kind reply.

    What I expect is to have A and B take their own covergroup, i.e. A with covergroup defined in class A while B has covergroup defined in class B. I've "new" both for A and B as below and assign distinct name for each by calling cg.set_inst_name(), which I think will have the same effect as cg.option.name = "".

    
reg clk=0;
always #5 clk = !clk;

class A;
    bit[1:0] a;

    covergroup cg @(clk);
    option.per_instance = 1;
    v_a: coverpoint a
        iff(reset){}
    endgroup // cg

function new;
    cg = new;
    cg.option.name = "A_group"; // optional
endfunction

endclass // A

class B extends A;
    bit[1:0] b;

    covergroup cg @(clk);
    option.per_instance = 1;
    v_b: coverpoint b
        iff(reset){}
    endgroup // cg

    function new;
    super.new;  // optional
    cg = new;
    cg.option.name = "B_group"; // optional
    endfunction 
endclass // B

A c_a;
B c_b;
initial
begin
    c_a = new;
    c_b = new;
    c_a.a = 1;
    c_b.a = 2;
    c_b.b = 3;
    #10 $finish;
end

    As the instance-based report shows, the A's covergroup still exists in B's covergroup (even without calling super.new in B), is there any way to ignore cov_A in cov_B?

    Thanks.

    
Name         Average, Covered Grade Line Source Code
c_a.A_group  25.00%, 25.00% (1/4)   299  covergroup cg (@clk);
|--v_a       25.00% (1/4)           301  coverpoint a
| --auto[0]  0.00% (0/1)            301  coverpoint a
| |--auto[1] 100.00% (39/1)         301  coverpoint a
| |--auto[2] 0.00% (0/1)            301  coverpoint a
| |--auto[3] 0.00% (0/1)            301  coverpoint a
c_b.A_group  25.00%, 25.00% (1/4)   299  covergroup cg (@clk);
| - -v_a     25.00% (1/4)           301  coverpoint a
| |--auto[0] 0.00% (0/1)            301  coverpoint a
| |--auto[1] 0.00% (0/1)            301  coverpoint a
| |--auto[2]  100.00% (39/1)         301  coverpoint a
| |--auto[3] 0.00% (0/1)            301  coverpoint a
c_b.B_group  25.00%, 25.00% (1/4)   315  covergroup cg (@clk);
|--v_b       25.00% (1/4)           317  coverpoint b
| |--auto[0] 0.00% (0/1)            317  coverpoint b
| |--auto[1] 0.00% (0/1)            317  coverpoint b
| |--auto[2] 0.00% (0/1)            317  coverpoint b
| |--auto[3] 100.00% (39/1)         317  coverpoint b
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