( ESNUG 272 Item 6 ) -------------------------------------------- [11/19/97]
Subject: ( ESNUG 271 #3 ) DC 97.08 & Problems With Parameterized Sub-modules
> Our fatal errors with 1997.08 are related to the use of parameterized
> sub-modules. If you analyze/elaborate a design that instantiates
> a parameterized block, dc_shell croaks just as it tries to build
> the sub-module. So far I've observed this on two separate designs.
> Since we make heavy use of parameterized blocks, this is a major
> roadblock for us.
>
> We're using Verilog, although I'm not sure yet if that's significant.
> Unlike Howard Landman, we don't use connection_class at all. For
> now, 1997.08 has been declared unfit for human consumption around
> here while I try to find a work-around.
From: "Tom Harrington" <tharring@ford.com>
John,
Since discovering problems with 1997.08, I've received a work-around from
Synopsys support. If we set the undocumented variable "dont_clean_design"
to "true", our fatal errors disappear. I've added this to our system-
wide setup script for dc_shell verion 1997.08. It's my understanding
that this variable only needs to be "true" when reading or elaborating
RTL code, but I wanted to make it as simple as possible for our users
to avoid the fatal errors we saw.
Results with this work-around are very similar to those produced by
1997.01; designs are either slower or faster, larger or smaller, by very
small amounts. Execution time seems to be 15-20% longer, though.
I've re-released 1997.08 to our users, but with the long execution times
I don't expect that many of them will use this version of Design Compiler.
Other tools may get used, though.
- Tom Harrington
Ford Microelectronics, Inc.
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