From: Shalom.Bresticker@motorola.com
Date: Wed Aug 14 2002 - 12:50:05 PDT
Precedence: bulk
The following reply was made to PR errata/84; it has been noted by GNATS.
From: Shalom.Bresticker@motorola.com
To: Steven Sharp <sharp@cadence.com>
Cc: etf-bugs@boyd.com
Subject: Re: errata/84: Should @* include delay controls?
Date: Wed, 14 Aug 2002 22:43:36 +0300 (IDT)
On Mon, 12 Aug 2002, Steven Sharp wrote:
> > But, regarding the "iterative vector indexing implicit sensitivity," at least
> in
> > the example you give, isn't that a case where i is a temporary variable
> assigned
> > before its use, where we say that it will not be included in the sensitivity
> > list?
>
> There is no such exception in the standard.
Really? Are you sure?
I was sure I had read it.
I don't have it with me to check.
> I don't know whether there was
> an attempt to put in such an exception at some point. I don't see a good way
> to add such an exception. In the general case, I believe that the question
> of whether a variable is guaranteed to be assigned before being used can be
> reduced to the halting problem, and is therefore uncomputable.
Not in the general case.
But there are cases where it is trivial.
E.g.,
always @*
begin
a = b ;
c = a ;
end
It is trivial to see that a is always assigned before being used.
Shalom
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