RE: [sv-bc] changing the lifetime of begin end block

The LRM defines the behavior of automatic variables in procedural blocks:

"Such variables have the lifetime of the call or block and are initialized on each entry to the call or block".

and

integer unsigned I;

is indeed legal.

The LRM says,

"The data types byte, shortint, int, integer, and longint default to signed. The data types bit, reg, and logic default to unsigned, as do arrays of these types. The signedness can be explicitly defined using the keywords signed and unsigned.

int unsigned ui;
int signed si;"

By the way, it was recently asked, and there was not a final answer, what is the meaning of "class static"?

Shalom

> -----Original Message-----
> From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On
> Behalf Of John Michael Williams
> Sent: Friday, February 12, 2010 7:22 AM
> To: sv-bc@eda.org
> Subject: Re: [sv-bc] changing the lifetime of begin end block
>
> Hi Steven.
>
> A variable not on a stack is NOT "automatic". Whether a keyword
> was used on it or not -- if it can not be deallocated AUTOMATICALLY
> because of exit of some process or thread, it is not an automatic
> variable.
>
> I think there is a confusion here over what "automatic" means.
> The LRM has to be modified, if this is a real confusion, rather
> than just a confusion during this discussion.
>
> For another example, what if I declared,
>
> "integer unsigned I;" ?
>
> Would the keyword make an integer "unsigned"? No,
> because an integer is defined as a 32-bit variable
> having a sign bit as its MSB.
>
> A conforming compiler should report an error if
> it encountered "module automatic mod1;" just
> as it should "integer unsigned I;"
>
> Steven Sharp wrote:
> > Note that in most cases, variables outside of tasks and
> functions don't
> > need to use automatic storage. There cannot be multiple
> activations of the
> > scope except in certain circumstances involving
> fork..join_any/join_none
> > inside loops. An implementation might try to optimize the
> other cases by
> > treating them as statics regardless of how they were
> declared. They might
> > go too far and allow hierarchical references to them as if
> they were static,
> > exposing this treatment. That would be a faulty
> optimization, but would
> > not necessarily indicate that these variables are not
> otherwise treated as
> > automatics.
> >
> > If you really want to test whether these variables default
> to automatic,
> > you should write a testcase that creates multiple
> simultaneous activations
> > of the scope, and see whether each gets its own storage.
> >
> > Steven Sharp
> > sharp@cadence.com
> >
> >
>
> --
> John Michael Williams
> jwill@BasicISP.net
>
>
> --
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