Re: [sv-ec] implicit sensitivity list and class dynamic members

From: Gordon Vreugdenhil <gordonv_at_.....>
Date: Fri Jul 24 2009 - 06:48:42 PDT
Daniel,

9.2.2.2.1 explicitly deals with always_comb:
    References to class objects and method calls of class objects do
    not add anything to the sensitivity list of an always_comb.

9.2.2.2.2 (on @(*)) is less clear although it claims that
    The SystemVerilog always_comb procedure differs from
    always @* (see 9.4.2.2) in the following ways:
       ...

Whether @(*) is sensitive to class refs was never explicitly
addressed in the LRM, but it would be reasonable to interpret
the lack of comment about classes in 9.2.2.2.2 to imply that
@(*) should be sensitized to class references either.

Gord.

Daniel Mlynek wrote:
> I've a question related to implicit sensitivity list (@*, always_comb). 
> This feature was assumed to help users in design code - for 
> combinatorial blocks. But in blocks under @* or always_comb also 
> references to dynamic class members can be used - as in below code. 
> Should such references be added to implicit sensitivity list>
> 
>     class class0;
>      int x; 
>     endclass
>      
>     module top_006;
>      class0 c0 = new;
>      class0 c1 = new; 
>      
>      initial begin
>         #10 c0.x = 1;
>         #10 c0.x = 0;
>         #10 c0.x = 1;
>         #10 c0 = c1; 
>      end
>      always@* $display($time, c0.x);        //should this be sensitive
>     to c0.x?
>     endmodule
> 
> DANiel
> 
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-- 
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Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com


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Received on Fri Jul 24 06:50:28 2009

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