( ESNUG 378 Item 4 ) -------------------------------------------- [10/03/01]
Subject: ( ESNUG 371 #14 ) We're Disappointed With Synopsys Presto, Too
> We're investigating using the new Synopsys Presto Verilog 2000 features
> like arrayed instantiation and multiply-dimensioned arrays. In our
> preliminary evaluations of Presto's support for these features,
> I have been sorely disappointed (using 2000.11-SP1). I have been even
> more disappointed by the Synopsys On Line Documentation provided
> describing Presto's support of these particular features.
>
> We have also encountered some serious backwards incompatibility with HDL
> Compiler issues (i.e., Verilog that works fine with HDL Compiler that
> breaks Presto), and Synopsys has publicly stated its intent to make Presto
> the default Verilog reader starting with the 2001.08 release.
>
> I would be very interested in hearing about others' experiences with
> Verilog 2000 and Presto to date.
>
> - Rich Conlin
> Paradigm Works Andover, MA
From: "Gabriel Ricardo" <Gabriel.Ricardo@tsc.tdk.com>
John,
This was for DC 2000.11. We subsequently abandoned the use of Presto so I
don't know if these problems have been fixed in later releases.
A couple of months ago I discovered that Presto (DC's new HDL Compiler)
doesn't have all the kinks worked out. Our team decided to use Presto's
support for new Verilog features in our RTL code. Specifically we had a
parameterizable design with many instances all configured differently and
we wanted to use Presto's support for the defparam construct to control the
overriding of parameters in each instance. Turned out defparam didn't do
what we wanted it to do. The construct would override the first two
parameters passed down and do nothing to the rest of the parameters.
Seems as though Presto is bug ridden. The Synopsys support engineer
conveyed that much to me through my email exchanges with them. So the
problem with defparam has been captured as a STAR, which had I known that
when I ran into the problem, would have saved me some time. It would be
nice if as a user, I could search a database for related STARs and any
known workarounds. But as I've been told by Synopsys support, Synopsys
makes it clear when a STAR is fixed but doesn't do much to let user's know
about "known" bugs. I think users should have access to a list of STARs
(and known workarounds) and how they impact the use of the tool. In all
fairness, I do have to say the Synopsys support was much better at getting
back to me this time.
So our project switched to using HDL Compiler and using the #(param, param
...) construct to override parameters. Switching to the older construct
and disabling the use of Presto wasn't such a big deal.
As I mentioned above, if I had been able to find out about the Presto STAR
up front it would have saved me a hassle.
- Gabriel Ricardo
TDK Semiconductor Nevada City, CA
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