RE: [sv-ac] immediate assert

Subject: RE: [sv-ac] immediate assert
From: Bassam Tabbara (bassam@novas.com)
Date: Tue Apr 22 2003 - 11:45:16 PDT

Arturo, I am just reading your email, I sent an exact opposite version
to sv-ac just now (although I never claimed to represent the scheduling
team :-) I did however back the thinking we did on this way back when).

I would agree with you only if the "statement" type in the action block
is restricted. In other words I do not mind the "immediate"
warnings/errors (i.e. give up on the "observe") since this is immediate
(may be we gave up on that already, I am probably revisiting that
portion...), however the "reactive" placing of the action_block is
tougher to give up on in my mind since that would entail additional
evals/races to the design portion e.g. we are not just saying:
Assert (....)
Else
  $error .....

But rather

Assert (....)
Else
   count = 7;
   #.... ????
   $error .....

Granted this is not a major headache, but I thought the intent was to
avoid worrying about it (potential for trouble is there). We worried
about this back in SV 3.0 before adding the additional scheduling
semantics/regions and coined side-effects and the like...

** That said, I will still defer to your and other expert opinion just
give me another run through, seems a drastic "correction" at this late
stage, ok ?

Thx.
-Bassam. 

--
Dr. Bassam Tabbara
Technical Manager, R&D
Novas Software, Inc.

http://www.novas.com
(408) 467-7893

> -----Original Message-----
> From: owner-sv-ac@server.eda.org 
> [mailto:owner-sv-ac@server.eda.org] On Behalf Of Arturo Salz
> Sent: Tuesday, April 22, 2003 11:16 AM
> To: sv-ac@server.eda.org; Surrendra Dudani; sv-ec@server.eda.org
> Subject: Re: [sv-ac] immediate assert
> 
> 
> Surrendra is absolutely correct.
> 
> Property assertions are declarative and do not have an 
> execution context 
> in which to execute the pass/fail action.  Thus, having them 
> execute in the 
> Reactive region gives users the ability to react to them in a 
> deterministic 
> manner, regardless of how vendors choose to implement the 
> property evaluation. Immediate assertions do have a well 
> defined execution context so there's no need to have them 
> execute anywhere other than in their context.
> 
>     Arturo
> 
> ----- Original Message ----- 
> From: "Surrendra Dudani" <Surrendra.Dudani@synopsys.COM>
> To: <sv-ac@eda.org>
> Sent: Tuesday, April 22, 2003 10:18 AM
> Subject: [sv-ac] immediate assert
> 
> 
> We came across one issue that seemed to have been overlooked. 
> This relates 
> to the execution of the action block for the immediate 
> assert. The draft5 
> LRM says that the action block gets executed in the reactive 
> region. This 
> is correct for the concurrent assertions, but not for the 
> immediate assertions. Since the immediate assertion is 
> treated like an "if" 
> statement, the action block should also execute like the if statement 
> true/false blocks. Otherwise, the values seen in the action 
> blocks would be 
> different that the values used for the evaluation. Also, since the 
> immediate assertion can be placed in the action blocks, its 
> execution would 
> have little use.
> 
> The suggestion for the change in the LRM is to execute the 
> action blocks 
> for the immediate assertions in the same region as the assert 
> statement itself. Surrendra
> 
> 
> **********************************************
> Surrendra A. Dudani
> Synopsys, Inc.
> 377 Simarano Drive, Suite 300
> Marlboro, MA 01752
> 
> Tel:   508-263-8072
> Fax:   508-263-8123
> email: Surrendra.Dudani@synopsys.com
> **********************************************
> 
>

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