( ESNUG 135 #1 ) -------------------------------------------------- [7/21/93]
From: jcooley@world.std.com (John Cooley)
Subject: Synopsys White Space / Comments Bug
As an ASIC design consultant, I usually find myself working at a customer's
site using quickly written Verilog or VHDL source code as working copy
which is later "cleaned up" with proper comments and spacing come
time to present the code to the client or it appears that I'm not going
to see the source code for a while.
Since I tend to use Synopsys a lot, I use it as a post clean-up syntax
checker.
While using Synopsys 3.0a-100052, I ran a "customer presentable" design
through Design Compiler and found that the design compiled to a different
gate count than expected. After some considerable examination (and
going back to the orginal non-presentable code) the different gate
count after compiling was caused by white space and comments!
To check this, I created four versions of the EXACT same design which differed
only in white space (blanks, tabs and newlines) and comments (both the
"//" and the "/* ... */" types). Using the exact same compile script for
each design, I got four different gate counts!
This bug was presented to Synopsys and they confirmed it. In addition,
they found:
Synopsys 3.0a Has the White Space / Comments Bug
Synopsys 3.0a-9746 Unknown Status
Synopsys 3.0a-100052 Has the White Space / Comments Bug
Synopsys 3.0a-100063 Does NOT have the White Space / Comments Bug
and Synopsys Technical Support sent the recommendation that customers
should upgrade to Synopsys 3.0a-100063 to avoid this problem. (The
other Synopsys 3.0a-XXXXX releases were specific bug patches for specific
sets of customers. Synopsys 3.0a-100063 incorporates ALL of these bug
patches plus some more bug patches plus some software enhancements.)
It's also a good idea to read the Synopsys v3.0a-100063 release notes
because there's an updated installation procedure amoungst the new
software enhancements. The only source of documentation for these
changes are in the release notes!
So, if you're not using Synopsys3.0a-100063, you should check with your
SysAdmin people because everyone who got a Synopsys 3.0a tape got a
Synopsys 3.0a-100063 tape. If you don't have one, call your local FAE.
- John Cooley
EDA & ASIC Design Consultant
(and ESNUG Moderator, too!)
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