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.

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> 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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> > > 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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