errata/566: Re: errata/566: 9.5: case item expression ambiguity

From: Brad Pierce (Brad.Pierce@synopsys.com)
Date: Wed Mar 24 2004 - 09:00:00 PST

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    The following reply was made to PR errata/566; it has been noted by GNATS.

    From: "Brad Pierce" <Brad.Pierce@synopsys.com>
    To: <etf-bugs@boyd.com>
    Cc:
    Subject: Re: errata/566: 9.5: case item expression ambiguity
    Date: Wed, 24 Mar 2004 09:08:10 -0800

     First, if this would effect the simulation efficiency
     of even those case statements without side-effecting
     case item expressions, then I wouldn't want it. I
     assumed that static analysis could determine which
     case statements are afflicted with this rather rare
     style, and treat only those case statements in the
     new way. If not, then never mind.
     
     Having said that, the reason I was attracted to your
     interpretation is that it seemed to fit better with
     the handling of full_case parallel_case pragmas, which,
     unlike side-effecting case item expressions, are very
     common. It seemed natural to pull out all the side-effects,
     do them in sequence, and only then do the case. (But
     maybe it's just me, because full_case parallel_case
     itself seems more natural to me than priority style.)
     
     -- Brad
     
     -----Original Message-----
     From: owner-etf@boyd.com [mailto:owner-etf@boyd.com]On Behalf Of
     Shalom.Bresticker@motorola.com
     Sent: Tuesday, March 23, 2004 7:40 PM
     To: etf-bugs@boyd.com
     Subject: errata/566: Re: errata/566: 9.5: case item expression ambiguity
     
     
     The following reply was made to PR errata/566; it has been noted by GNATS.
     
     From: Shalom.Bresticker@motorola.com
     To: Brad Pierce <Brad.Pierce@synopsys.com>
     Cc: etf-bugs@boyd.com
     Subject: Re: errata/566: 9.5: case item expression ambiguity
     Date: Wed, 24 Mar 2004 05:49:51 +0200 (IST)
     
      Why do you want them to be evaluated before the comparisons?
     
    > The text could specify that, just as with the case expression
    > in parentheses, all the case item expressions shall be evaluated
    > exactly once, in order, and before any comparisons. The only time
    > one would notice the difference would be in the presence of
     side-effects.
     
     

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