RE: [sv-bc] E-mail ballot: DUE 8am PST, Jan 21, 2008

I vote NO on 2008 because I think the concerns 1) through 3) raised by Doug
need to be addressed.

Regarding 4), I think this is one of those rare times that it is important
to break backward compatibility.  My experience is that unique case is
frequently used in pure combinational logic blocks, and the current behavior
is broken.  I see the backward compatibility issue as minor.  It is similar
to the logic Z extension beyond 32 bits that we added in Verilog-2001.  It
is not backward compatible, but existing user models that have the problem
have already worked around it, so the impact on existing models is minimal,
if not non-existent. 

Stu
~~~~~~~~~~~~~~~~~~~~~~~~~
Stuart Sutherland
stuart@sutherland-hdl.com
+1-503-692-0898

> -----Original Message-----
> From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On
> Behalf Of Warmke, Doug
> Sent: Tuesday, January 15, 2008 12:22 AM
> To: Maidment, Matthew R; sv-bc@server.eda.org
> Subject: RE: [sv-bc] E-mail ballot: DUE 8am PST, Jan 21, 2008
> 
> Hello all,
> 
> 
> 
> I vote No on Mantis 2008 for the following reasons:
> 
> 
> 
> 1)      The related Mantis 2005 has been rewritten such that the event-
> control
> form of the syntax is no longer present.  That had too many unresolved
> issues,
> 
> so SV-AC decided to postpone that enhancement until sometime in the
> future.
> 
> Thus, the event-control aspect of 2008 should be removed, too.
> 
> 2)      The example in the unique/priority if area specifically
> mentions a 4 ns delay.
> But that is not actually the case in the example.  Rather, this is an
> example
> that is immune to zero-delay glitches in the active region set.  Note
> that
> evaluation of the unique-ness/priority-ness of the conditions is
> supposed
> 
> to happen in the Observed region, as per alignment with the deferred
> assertion feature of Mantis 2005.  Thus, "zero-delay glitch" isn't
> quite an
> 
> accurate term.  It should be "zero-delay glitch in the active region
> set".
> 
> (Since oddball glitches caused by zero-delay oscillations across the
> 
> active and reactive region sets would still fire the violation checks)
> 
> 3)      Speaking of "violation checks", I would prefer it if 2008
> caused that wording
> 
> to be used when describing unique/priority if/case.
> 
> 4)      I'm not in favor of the compatibility break.  I think that the
> proposed default
> behavior is too sophisticated to be allowed without the #0 syntactic
> clue.
> It's not hard to add those #0 into the source code, and it does give
> the
> reader the clue that unique/priority violations will be checked with
> some
> zero-delay semantic.  In addition, the current version of the construct
> can
> 
> work fine if placed in clocked procedures that include logic when
> assigning
> the clocked output variables of the procedure.  (Thus, the current
> semantics
> 
> aren't totally useless, though I do agree they are pretty useless for
> combinational
> 
> procedures)
> 
> 
> 
> I'd like to hear what others have to say about 4).
> 
> If there was enough weight in favor of making the compatibility break,
> 
> I will lift this particular objection, since I do think 2008 has a lot
> of value
> 
> and should be passed in this version of the standard.
> 
> 
> 
> Regards,
> 
> Doug
> 
> 
> 
> From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On
> Behalf Of Maidment, Matthew R
> Sent: Monday, January 14, 2008 4:53 PM
> To: sv-bc@server.eda.org
> Subject: [sv-bc] E-mail ballot: DUE 8am PST, Jan 21, 2008
> 
> 
> 
> 
> 
> -You have until 8am PST, Monday, January 21, 2008 to respond
> -An issue passes if there are zero NO votes and half of the eligible
>  voters respond with a YES vote.
> -If you vote NO on any issue, your vote must be accompanied by a
> reason.
>  The issue will then be up for discussion during a future conference
> call.
> -Note: For some issues, the proposed action is captured in the bug note
>        (resolve as duplicate, already addressed, etc.).
> 
> As of the January 7, 2008 meeting, the eligible voters are:
> 
> Brad Pierce
> Shalom Bresticker
> Cliff Cummings
> Mark Hartoog
> Francoise Martinolle
> Karen Pieper
> Dave Rich
> Steven Sharp
> Gordon Vreugdenhil
> Stu Sutherland
> Alex Gran
> Don Mills
> Heath Chambers
> Tom Alsop
> Doug Warmke
> Mike Burns
> 
> SVDB 2008 ___Yes   ___No
> http://www.eda.org/svdb/view.php?id=2008
> <http://www.eda.org/svdb/view.php?id=2008>
> 
> 
> 
> 
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