RE: [sv-bc] Re: [sv-ac] Is concurrent assertion not allowed inside task/function?

To answer Srini's question, yes, calling the same task from multiple
always blocks creates a bookkeeping problem for identifying unique
assertions. You can even have the same bookkeeping problem within a
single always block because there can be multiple paths to calling the
same task. Without any restrictions, you would essentially need to
identify an assertion by a dynamically created call stack.

 

Dave

 

 

________________________________

From: owner-sv-ac@server.eda.org [mailto:owner-sv-ac@server.eda.org] On
Behalf Of Korchemny, Dmitry
Sent: Tuesday, December 15, 2009 8:18 AM
To: Srinivasan Venkataramanan
Cc: Surya Pratik Saha; Abhishek Muchandikar; sv-bc@eda.org;
sv-ac@server.eda.org; Adhip Das
Subject: RE: [sv-bc] Re: [sv-ac] Is concurrent assertion not allowed
inside task/function?

 

But these are syntactical limitations. I am not talking that this cannot
be allowed, and I even think it would be useful to allow concurrent
assertions in functions and tasks, but it requires some additional
definition work that has not been completed yet.

 

Thanks,

Dmitry

 

From: Srinivasan Venkataramanan [mailto:svenka3@gmail.com] 
Sent: Tuesday, December 15, 2009 5:43 PM
To: Korchemny, Dmitry
Cc: Surya Pratik Saha; Abhishek Muchandikar; sv-bc@eda.org;
sv-ac@server.eda.org; Adhip Das
Subject: Re: [sv-bc] Re: [sv-ac] Is concurrent assertion not allowed
inside task/function?

 

But I believe allowing it inside "always" is in some cases is equivalent
to allowing it inside "task" - potentially two different modeling
styles, are there semantic concerns (a task maybe called by several
always blocks etc.?). 

 

Functions - maybe (though join_none is allowed, so if we were to think
of "spawning threads" it is similar).

 

Thanks

Srini

www.cvcblr.com 

On Tue, Dec 15, 2009 at 8:16 PM, Korchemny, Dmitry
<dmitry.korchemny@intel.com> wrote:

Hi Surya,

I was wrong about the BNF, but note the following:


The LRM states explicitly in 16.15 Concurrent assertions:

A concurrent assertion statement may be specified in any of the
following:
- An always procedure or initial procedure as a statement, wherever
these procedures may appear (see
9.2)
- A module
- An interface
- A program
- A generate block
- A checker

Thanks,
Dmitry



-----Original Message-----
From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On
Behalf Of Surya Pratik Saha
Sent: Tuesday, December 15, 2009 12:02 PM
To: Abhishek Muchandikar
Cc: sv-bc@eda.org; sv-ac@server.eda.org; Adhip Das
Subject: [sv-bc] Re: [sv-ac] Is concurrent assertion not allowed inside
task/function?

Hi Abhishek,
Then LRM should have some text restricting that, but there is nothing
like that. Is there any Mantis?

Hi Shalom,
BNF of both SV 2005 and SV 2009 draft 7a LRM allows it. Here is the
snippet:

task_declaration ::= task [ lifetime ] task_body_declaration
task_body_declaration ::=
[ interface_identifier . | class_scope ] task_identifier ;
{ tf_item_declaration }
{ statement_or_null }
endtask [ : task_identifier ]

statement_or_null ::=
statement
| { attribute_instance } ;
statement ::= [ block_identifier : ] { attribute_instance }
statement_item
statement_item ::=
[...]
| procedural_assertion_statement
[...]

procedural_assertion_statement ::=
concurrent_assertion_statement
| immediate_assertion_statement
| checker_instantiation

So BNF does not restrict it.

Regards
Surya



-------- Original Message  --------
Subject: Re:[sv-ac] Is concurrent assertion not allowed inside
task/function?
From: Abhishek Muchandikar <Abhishek.Muchandikar@synopsys.com>
To: Surya Pratik Saha <spsaha@cal.interrasystems.com>, sv-bc@eda.org
<sv-bc@eda.org>, sv-ac@server.eda.org <sv-ac@eda.org>
Cc: Adhip Das <adhip@cal.interrasystems.com>
Date: Tuesday, December 15, 2009 3:20:36 PM
> Hi,
>
> In my views, the core functionality of tasks and functions restricts
such a kind of use model and is correct.
> The intended use model for tasks and functions is ability to execute
common procedures.
> The result of these execution is either passed as a single value thru
function or thru output/inout args from a task.
>
> How do you plan to see the assertion results thru them for a whole
bunch of assertions encapsulate in them,
> By nature assertion are declarative in form , spanning over the
temporal domain.
>
> Also since functions are supposed to  execute in one time unit, it
really is not feasible to have assertions in them spanning over a period
of time.
>
> Thanks
> Abhishek
>
> -----Original Message-----
> From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
Surya Pratik Saha
> Sent: Tuesday, December 15, 2009 2:40 PM
> To: sv-bc@eda.org; sv-ac@server.eda.org
> Cc: Adhip Das
> Subject: [sv-ac] Is concurrent assertion not allowed inside
task/function?
>
> Hi,
> I did not see any restriction in the LRM that prevents concurrent
> assertion statement inside task/function. Though all the standard
> simulators fail for the following case for same reason:
>
> module top(input clk,a,b,c);
>
>         property prop;
>                 @(posedge clk)  a ##1 b ##1 c;
>         endproperty
>         task tsk;
>                 assert property(prop)
>                             $display("\n time = %g , testname = %s
Passed",$time,"test1_16_7");
>                         else
>                             $display("\n time = %g , testname = %s
> Failed",$time,"test1_16_7");
>
>         endtask
>
>         function func();
>                 assert property(prop)
>                             $display("\n time = %g , testname = %s
> Passed",$time,"test1_16_7");
>                         else
>                             $display("\n time = %g , testname = %s
> Failed",$time,"test1_16_7");
>
>         endfunction
>
> endmodule
>
> Please comment on it.
>
>

 

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