Re: [sv-bc] Simulation semantics of deferred assertions (Mantis 3206)

Hi Dmitry,

My suggestion is to leave things as they are and not write assertions
that suffer from this problem.

Neil

On 11/05/10 17:24, Korchemny, Dmitry wrote:
> Hi all,
>
>
>
> Deferred assertions were designed to avoid simulation glitches. However
> simulation glitches are still possible when some of the assertion
> subexpressions are evaluated in the Active region and the others in the
> Reactive one. In this case the assertion matures twice: the first time
> when it reaches the Observed region for the first time, and the second
> time when it reaches it again upon the evaluation in the Reactive
> region. One such example is discussed in Mantis 3206
> (http://www.eda-stds.org/mantis/file_download.php?file_id=4571&type=bug
> <http://www.eda-stds.org/mantis/file_download.php?file_id=4571&type=bug>).
> This situation is going also to occur in checkers when the continuous
> assignments in checkers are introduced.
>
>
>
> To address these problems the simulation semantics of deferred
> assertions should be changed. I can think of the following options:
>
> 1. Make assertions mature in the Postponed region instead of the
> Observed one. The advantage of this solution is its simplicity, the
> obvious disadvantage is the inability to change anything from the
> assertion action blocks.
>
> 2. Require deferred assertions to “make two full iterations through
> simulation regions”, and make them mature only starting at the second
> visit in the Observed region. The advantages is the ability to change
> design variables from the assertion action blocks (e.g., to count), its
> disadvantage is performance penalty and more complicate simulation
> semantics.
>
>
>
> What would you suggest?
>
>
>
> Thanks,
>
> Dmitry
>
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