RE: [sv-ac] idea of multi matches for cover

So you may add "cover sequence" to list of deprecated contstruct at once;)
because it will slow down the simulation heavily for some kinds of sequences



DANiel 

-----Original Message-----
From: Fais Yaniv [mailto:yaniv.fais@freescale.com] 
Sent: Wednesday, November 21, 2007 11:48 AM
To: danielm; Korchemny, Dmitry; Neil.Korpusik@sun.com
Cc: sv-ac@eda-stds.org
Subject: RE: [sv-ac] idea of multi matches for cover


Hi, 

it was poorly defined in the 2005 version but in the current version of the
LRM (2008 draft 4) it is defined properly such that for a cover property
only one match should count and cause an execution of the action block.


 16.14.3 

"The difference between the two categories is that for sequence coverage,
all matches per evaluation attempt are reported, whereas for property
coverage the coverage count is incremented at most once per evaluation
Attempt"
....
for cover property:
"The pass statement specified in statement_or_null shall be executed once
for each successful evaluation attempt of the underlying property_spec"

For cover sequence:
...
"For a given attempt of the cover sequence statement, all matches of the
sequence_expr that complete without the occurrence of the disable iff
condition shall be counted, with multiplicity, toward the total number of
times matched for the attempt. No other match shall be counted towards the
total for the attempt.
The pass statement specified in statement_or_null shall be executed, with
multiplicity, for each match that is counted toward the total for the
attempt."


Yaniv


-----Original Message-----
From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of danielm
Sent: Wednesday, November 21, 2007 12:19
To: 'Korchemny, Dmitry'; Neil.Korpusik@sun.com
Cc: sv-ac@eda-stds.org
Subject: RE: [sv-ac] idea of multi matches for cover

This is obvious that both assertion and cover should be checked for each
evaluation attempt, and lets say that  this is also ok. 

That tool may limit reports.

The problem is action blocks. Standard has to define how it should work.
IMHO currently standard defines that for cover each attempt (each starting
time) may have multiple covers (cover action block will be executed ) while
for assertion the same property for single attempt will have single result
(pass, fail, vacuous fail, disable) and action block will be called once.

So the language is responsible for control action block behavior (exactly
like it was done for vacuous passes mantis  0001361)


DANiel

-----Original Message-----
From: Korchemny, Dmitry [mailto:dmitry.korchemny@intel.com]
Sent: Wednesday, November 21, 2007 9:06 AM
To: danielm; Neil.Korpusik@sun.com
Cc: sv-ac@server.eda-stds.org
Subject: RE: [sv-ac] idea of multi matches for cover

Hi Daniel,

According to the LRM both assert and cover statement will be checked for
each evaluation attempt. I am not sure the LRM should prescribe the way to
limit the number of reports by some predefined constant, it might be just a
tool option. There is always a vague boundary between what should be
standardized and what shouldn't.

Regards,
Dmitry

-----Original Message-----
From: owner-sv-ac@server.eda.org [mailto:owner-sv-ac@server.eda.org] On
Behalf Of danielm
Sent: Wednesday, November 21, 2007 9:46 AM
To: Neil.Korpusik@sun.com
Cc: sv-ac@server.eda-stds.org
Subject: RE: [sv-ac] idea of multi matches for cover

I think that here we hit some kind of misunderstanding.
I mean stmt like:
	cover property(a ##[1:$] b); 

For single a occurence above have to be checked and raported till EOS, while

	assert property (a ##[1:$] b);
Will not be checked and raported after first occuerence of a ##N b

So for cover we may get huge output, and simulation slowdown much bigger
than for assertion.

I just want to have the way to switch raports for "extra" passes of
assertion.

DANiel

-----Original Message-----
From: Neil.Korpusik@Sun.COM [mailto:Neil.Korpusik@Sun.COM]
Sent: Tuesday, November 20, 2007 7:29 PM
To: danielm
Cc: sv-ac@eda-stds.org
Subject: Re: [sv-ac] idea of multi matches for cover

Hi Daniel,

I suggest that you review 18.3, which describes the strobe option for
covergroups. Conceptually this is similar to what you are suggesting.

Neil



danielm wrote On 11/20/07 04:13 AM,:
> LRM wants that cover in contrast to assert and assume should react on 
> all matches of sequence. This aproach may have big impact on 
> simulation performance - in some case properties used in cover wil 
> have to be tracked from start point till end of simulation. Maybe 
> there should be way to turn off such extra passes - similarly to 
> switching off vacuous passes (see mantis  0001361) Such possibility to

> turn on off extra passes should be added to covers but also to assert 
> and assume.
>  
> 
> LRM about cover directive> In addition, statement_or_null gets 
> executed for every match. If there are multiple matches at the same 
> time, the statement gets executed multiple times, one for each match.
> 
>  
> 
> DANiel
> 
> 
> --
> This message has been scanned for viruses and dangerous content by
> *MailScanner* <http://www.mailscanner.info/>, and is believed to be 
> clean.



--
This message has been scanned for viruses and dangerous content by
MailScanner, and is believed to be clean.
---------------------------------------------------------------------
Intel Israel (74) Limited

This e-mail and any attachments may contain confidential material for the
sole use of the intended recipient(s). Any review or distribution by others
is strictly prohibited. If you are not the intended recipient, please
contact the sender and delete all copies.


--
This message has been scanned for viruses and dangerous content by
MailScanner, and is believed to be clean.


-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.