Re: [sv-ec] Query Regarding Coverpoints

Sandeep --

This was clarified in the 2008 version of the specification. The latest 
2008 draft is now available for purchase through the IEEE, I believe; if 
you don't have it, I highly recommend it.

Whether or not you consider that the covergroup has "two different 
objects of the same name", the rules for visibility have been clarified 
so that only one type of object is visible in a given context. To quote:

> A coverpoint name has limited visibility. An identifier can only refer 
> to a coverpoint in the following contexts:
> — In the coverpoint list of a cross declaration (see 18.6),
> — In a hierarchical name where the prefix specifies the name of a 
> covergroup variable. For example,
> cov1.cp.option.weight where cov1 is the name of a covergroup variable 
> and cp is the name of
> a coverpoint declared within the covergroup.
> — Following ::, where the left operand of the scope resolution 
> operator refers to a covergroup. For
> example, covtype :: cp :: type_option.weight.

In other contexts -- which includes at least option assignments within 
the covergroup, the coverpoint declaration itself, and of course bin 
declarations (though not in the case of a ref argument like "ra") -- the 
name could not refer to the coverpoint.

By the way, I have just realized that "binsof" expressions should be 
added to the list above for coverpoint name visibility.

Anyway, with this rule, it is unambiguous what "ra" means in a given 
context.

-- Dave Scott, Mentor Graphics


Sandeep Dasgupta wrote:
> Hi,
>
> I have the following query regarding coverpoints,
>
> Consider the test case as is given in IEEE Std 1800-2005, section 18.4,
> covergroup gc (ref int ra, int low, int high ) @(posedge clk);
> coverpoint ra // sample variable passed by reference
> {
> bins good = { [low : high] };
> bins bad[] = default;
> }
> endgroup
>
> Now as per section 18.4 "Defining coverage points",
> A coverage point creates a hierarchical scope and can be optionally 
> labeled. If the label is specified, then it
> designates the name of the coverage point. This name can be used to 
> add this coverage point to a cross coverage
> specification or to access the methods of the coverage point. If the 
> label is omitted and the coverage
> point is associated with a single variable, then the variable name 
> becomes the name of the coverage point.
>
> So as per the above specification, the coverpoint used in the example 
> above should be labeled with
> the name of the single variable associated with the coverpoint, i.e. ra.
> Also the covergroup gc contain a variable with the same name, ref int ra.
> So is it possible for a scope (in this case a covergroup scope) to 
> have two objects with same name(in this case ra )?
> Please give your suggestions.
>
>
> Thanks and Regards,
> Sandeep Dasgupta.
>
>
>
>
>
>
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>


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