Re: [sv-ec] Query Regarding Coverpoints

SV-EC members,

I think Ray's Mantis 1279 -- approved long ago, I know -- missed a 
context in which an identifier can refer to a coverpoint.  See the 
quotation below from 18.5 in my response to Sandeep Dasgupta.

That list needs to include "binsof" expressions (in the cross bin 
declaration syntax, the "bins_expression" production), as clearly those 
can refer to a coverpoint.

Do we require that this list be complete?  It seems to me yes.

If you'd like me to file another Mantis, please let me know.  Presumably 
we'd leave 1279 alone and file a new one?

Dave S


David Scott wrote:
> 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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