RE: [sv-ec]e-mail ballot Closes Wednesday February 20 2008, 11:59pm PST

Hi Gord,

I don't think that let is an issue here since the let construct cannot
be used to define covergroup elements even in checkers, so from this
point of view the situation should not be different from covergroups in
modules.

Regards,
Dmitry

-----Original Message-----
From: owner-sv-ec@server.eda.org [mailto:owner-sv-ec@server.eda.org] On
Behalf Of Gordon Vreugdenhil
Sent: Friday, February 15, 2008 1:30 AM
To: Mehdi Mohtashemi
Cc: sv-ec@server.eda-stds.org
Subject: Re: [sv-ec]e-mail ballot Closes Wednesday February 20 2008,
11:59pm PST



Mehdi Mohtashemi wrote:
>  We are conducting an email based on request from SV-AC on the
following
> mantis items:  2088 and 2089.
> 
> the latest documents associated with the mantis items are:
>  2088_covergroups_20080211.pdf
>  2089_finalInChecker_20080129.pdf
...
> 
>  Please mark your vote below by an x. If No, then specify a reason. 
>  Send it to the reflector.
> 
>  2088  ___ Yes   _X_ No  
> http://www.eda.org/svdb/view.php?id=2088    


No for a couple of reasons.  First, I need more time to be
able to adequately review this.  Second, the interactions
between the type space (the covergroup type) and the checker
"instantiations" are not obvious to me.  Is a checker
now a sneaky way of introducing type declarations (covergroups)
into a procedural (even conditional) block?   What
assumptions are being made about whether new covergroup
types are introduced with such checker "instantiations"?
Remember -- covergroups have class-static properties so
type uniqueness is important to have absolutely clear.
Are unreachable (sequentially dead) covergroup types
still alive?  When are they created (via the "new") in
such scenarios?  Can a covergroup look at a free var from
the checker?

I am also concerned that there might be lurking assumptions
about essentially having "macro like" expansions involving
"let" and other untyped aspects.  All of this is related
to my early serious objections to "let" and checkers as
a whole and how they interact with the rest of the language.
"let" was tied down to only be used in assertions
constructs but now AC needs to inject a non-assertions
construct back into an assertions context.  Many of
my earlier concerns are likely going to reappear in
this context as well.

In short, there are all sorts of interactions here that are
not at all obvious to me and could pose major issues unless
the instantiation points of checkers with covergroups are
restricted to contexts in which a covergroup type itself
is a legal declaration.


>  2089  ___ Yes   _X_ No  
> http://www.eda.org/svdb/view.php?id=2089   

Similarly here, there are unanswered questions.  If checker
is "instantiated" in a loop or conditional sequential
construct, in what state is its "final" block?  What if
the checker is not sequentially reachable?  The final
is allowed to read from checker vars -- does that include
free vars?


Gord
-- 
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Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com


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