RE: [sv-ac] sequence as clocking event to covergroup

True... actually I missed that in the LRM. But is this a good solution?
Would uniqueness even if chosen non-deterministically be better? (I
know, local variables...)

ed


> -----Original Message-----
> From: John Havlicek [mailto:john.havlicek@freescale.com] 
> Sent: Monday, January 15, 2007 9:33 AM
> To: Eduard.Cerny@synopsys.COM
> Cc: john.havlicek@freescale.com; tej_singh@mentor.com; sv-ac@eda.org
> Subject: Re: [sv-ac] sequence as clocking event to covergroup
> 
> Hi Ed:
> 
> Your suggestion contradicts what we already have
> written about first_match in section 17.
> 
> Do you intend to make this inconsistent with the
> currently existing first_match semantics?
> 
> J.H.
> 
> > X-MimeOLE: Produced By Microsoft Exchange V6.5
> > Content-class: urn:content-classes:message
> > Date: Mon, 15 Jan 2007 06:27:41 -0800
> > Thread-Topic: [sv-ac] sequence as clocking event to covergroup
> > Thread-Index: Acc3Yk/jxmzGV+eTSIWbGNAy5ZE/HwBTrOYg
> > From: "Eduard Cerny" <Eduard.Cerny@synopsys.com>
> > Cc: <sv-ac@eda.org>
> > X-OriginalArrivalTime: 15 Jan 2007 14:27:43.0158 (UTC) 
> FILETIME=[5187F560:01C738B1]
> > 
> > Hi John,
> > 
> > I agree with you that the covergroup should trigger on 
> multiple matches
> > of a seuqnce, but I think that with first_match it should 
> give only one
> > match even if there are possible multiple matches (by choosing
> > non-deterministically one of them).=20
> > 
> > Regards,
> > ed
> > 
> > 
> > > -----Original Message-----
> > > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On=20
> > > Behalf Of John Havlicek
> > > Sent: Monday, January 08, 2007 9:31 AM
> > > To: tej_singh@mentor.com
> > > Cc: sv-ac@eda.org
> > > Subject: Re: [sv-ac] sequence as clocking event to covergroup
> > >=20
> > > Hi Tej:
> > >=20
> > > I have a few comments.
> > >=20
> > > It is true that the LRM does not give a complete definition of
> > > multiplicity of matching and of when matching occurs.  On 
> the other
> > > hand, the LRM also does not leave these things completely 
> undefined.
> > >=20
> > > I think that if a covergroup has a sequence instance as 
> its clocking
> > > event, then multiple matches of the sequence instance in the same
> > > timestep should result in multiple triggerings of the covergroup.
> > >=20
> > > I think we should avoid allowing the rules for multiplicity=20
> > > of covergroup
> > > triggering on sequences to differ from the rules for 
> multiplicity of
> > > matching that apply in other scenarios, e.g.
> > >=20
> > >    cover property (
> > >       @(posedge clk)
> > >       sequence_instance ##0 (1, task_call);
> > >    );
> > >=20
> > > I don't like the idea of trying to incorporate 
> first_match into the
> > > semantics of covergroups with sequence clocking event.  I 
> think the=20
> > > user can use first_match in defining a sequence, but then 
> the general
> > > rules for multiplicity of sequence matching should apply.
> > >=20
> > > In particular, a first_match can have multiplicity, e.g. if both
> > > a ##1 b and c ##1 d match over a two-cycle interval, then=20
> > >=20
> > >    first_match((a ##1 b) or (c ##1 d))
> > >=20
> > > should match with multiplicity two over that interval.
> > >=20
> > > Best regards,
> > >=20
> > > John H.
> > >=20
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> > > > Date: Wed, 6 Dec 2006 15:12:02 -0800
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> > > > Thread-Topic: [sv-ac] sequence as clocking event to covergroup
> > > > Thread-Index: =
> > AccZfiKOmZ5lYIN/QgGxOLcn04V72QABWXHgAAFLp5AAAHSA7A=3D=3D
> > > > From: "Singh, Tej" <tej_singh@mentor.com>
> > > > Cc: <sv-ac@eda.org>
> > > > X-OriginalArrivalTime: 06 Dec 2006 23:12:03.0364 (UTC)=20
> > > FILETIME=3D[F0C06E40:01C7198B]
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> > > >=20
> > > > This is a multi-part message in MIME format.
> > > >=20
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> > > >=20
> > > > But as Doron pointed out, the LRM does not define the=20
> > > number of threads.
> > > >=20
> > > > How about defining it so that the number of events at a=20
> > > clock is same as
> > > > number of sequence attempts that matched at that clock.=20
> > > This is what I =3D
> > > > was trying
> > > > to do with first_match but first_match will kill any 
> future matches.
> > > >=20
> > > > So for a sequence expr that looks like
> > > >=20
> > > > a ##[1:$](b ##1 c) or (d ##1 e)
> > > >=20
> > > > it will not matter whether 'or' results in two matches or=20
> > > one match =3D
> > > > since
> > > > both correspond to the same attempt.=3D20
> > > >=20
> > > > Tej
> > > >=20
> > > >=20
> > >=20
> > > --=20
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> > >=20
> > >=20
> 

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