RE: [sv-ec] RE: [sv-bc] Can a function contain a fork/join/any/none?

Arturo,

I agree the question is valid.
The reason I have the answer I do is to provide for
a means of singleton object construction and destruction.

Even if others don't agree with my take on it, I still think the
LRM should address the issue about allocation and initialization
of declaration initializers for package items that are not explicitly
imported into the simulation's elaborated image.

Note that this issue can apply in a few scenarios:
1. A package contains multiple object declarations with initializers.
   Some are imported or explicitly referenced, others are not.
   Are the unimported objects allocated and initialized?
2. A package contains multiple object declarations with initializers.
   A wildcard import statement in the design references the package,
   but in fact no items are imported from the package at all.
   Are any objects in the package allocated and initialized?
3. A package is somehow included in a simulation database, but there
   are no import statements or explicit references to the package.
   Are any objects in the package allocated and initialized?

Probably 3 is out of the scope of the LRM.  I would expect that
if a tool did provide a means for inclusion of such a package in
the simulation database, the answer to 3 would follow the pattern
established in 1 and 2.

For ease of reasoning and intuitive behavior, I would like the
answers to questions 1 and 2 to be "yes".  This also allows users
the possibility of singleton initializer function semantics.
If an implementation determines that an initializer function has
no side effects, then it can optimize away calls to that function.

We should address both issues 1 and 2 in the LRM.
Otherwise we'll get into a lack of portability across tools.

If SV-EC agrees with my answers of "yes", I can create a proposal
instituting this semantic in the LRM.

If anyone thinks "no" is the right answer, please explain.

Regards,
Doug
 

-----Original Message-----
From: Arturo Salz [mailto:Arturo.Salz@synopsys.com] 
Sent: Friday, February 24, 2006 1:19 AM
To: Warmke, Doug; Rich, Dave; sv-bc@eda.org; sv-ec@eda.org
Subject: RE: [sv-ec] RE: [sv-bc] Can a function contain a
fork/join/any/none?

Doug,

But, Dave's question is still valid. If a package is (by some
unspecified tool dependent mechanism) included in a design but no
element from the package is imported either via an import statement or
using the package-qualified name then should the simulator even allocate
and execute the declaration initializers (which may contain functions
with additional side effects)?  And, if no data from a package is ever
used and no function from the package is ever called, should the
simulator even call the corresponding final block (assuming we allow
that).

So is this behavior just an optimization, or something that the LRM
should address.

	Arturo

-----Original Message-----
From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
Warmke, Doug
Sent: Thursday, February 23, 2006 4:30 PM
To: Rich, Dave; sv-bc@eda.org; sv-ec@eda.org
Subject: RE: [sv-ec] RE: [sv-bc] Can a function contain a
fork/join/any/none?

Dave,

I would like the answer to your question to be "yes".
And I think this should be specified in the LRM.

That way folks could count on using VDA's in packages
as a way of getting singleton initialization code
to run.

SV currently lacks a way to run singleton destruction
code based in packages.

See http://www.eda.org/svdb/bug_view_page.php?bug_id=0000878,
which expresses the possibility of allowing final blocks to
be declared in packages for this purpose.

I also thought of Francoise's refinement points, but she
beat me to the punch on those.

Regards,
Doug

 

> -----Original Message-----
> From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On 
> Behalf Of Rich, Dave
> Sent: Thursday, February 23, 2006 3:14 PM
> To: Steven Sharp; sv-ec@eda.org; sv-bc@eda.org; 
> Arturo.Salz@synopsys.com
> Subject: RE: [sv-ec] RE: [sv-bc] Can a function contain a 
> fork/join/any/none?
> 
> This raises the question "Does a package exist if no one imports it?"
> Having static space allocated by an unused package is not usually an
> issue, but if it creates threads, I can see that as being a problem. I
> vaguely remember this as the reason that modules and continuous
> assignments were not allowed in packages. 
> 
> > -----Original Message-----
> > From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
> Steven
> > Sharp
> > Sent: Thursday, February 23, 2006 12:24 PM
> > To: sharp@cadence.com; sv-ec@eda.org; sv-bc@eda.org;
> > Arturo.Salz@synopsys.com
> > Subject: RE: [sv-ec] RE: [sv-bc] Can a function contain a
> > fork/join/any/none?
> > 
> > 
> > >[Arturo]
> > >My point is that all of these issues exist in other 
> contexts and the
> > >tools must be able to deal with them. By extension, these do not
> > >represent any fundamental or implementation problem.
> > 
> > But Dave has pointed out that this allows some things that are not
> > possible with functions triggering other processes, or with tasks.
> > In particular, it allows creating a thread whose parent is a
> > variable initialization.  This in turn means it has allowed root
> > threads to be created in a package, which could not happen before.
> > 
> > I don't know what specific problems Dave is concerned this 
> will cause.
> > 
> > Steven Sharp
> > sharp@cadence.com
> 
> 
>