( ESNUG 468 Item 7 ) -------------------------------------------- [09/13/07]

Subject: ( ESNUG 467 #3 ) That DC "bad logic" bug was in version 2006.06

> Yes, DC did create bad logic.  We struggled together with the Synopsys R&D
> folks to figure out the root cause.  We were given multiple patches, but
> the bug persisted.  Due to lack of time, we couldn't afford anymore
> debugging and switched to BlastCreate.  Synopsys claimed that it was a
> "ghost bug" which appeared once in a while.  Unfortunately, in our case,
> on that specific design it happened every time.
>
>     - Jay Pragasam
>       PLX Technology                             Sunnyvale, CA


From: Linming Jin <ljin=user domain=brocade not calm>
To: Akhil Bagri <akhil.bagri=user domain=synopsys not calm>

Hi, Akhil,

I'd appreciate if you can get the detail of "bad logic".  What is the DC
"ghost bug"?  Is it fixed?

    - Linming Jin
      Brocade Communications                     San Jose, CA

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From: Akhil Bagri <akhil.bagri=user domain=synopsys not calm>
To: Linming Jin <ljin=user domain=brocade not calm>

Sure, Linming! Let me look into it.

I believe this Star to be more then a year old that has already been fixed.
Anyhow, I will get back to you with more details on it.

    - Akhil Bagri
      Synopsys, Inc.                             Mountain View, CA

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From: Akhil Bagri <akhil.bagri=user domain=synopsys not calm>
To: Linming Jin <ljin=user domain=brocade not calm>

Hi, Linming,

I was able to gather some more information on that bad-logic bug.

As I mentioned earlier, it is over a year old and was reported with the
2006.06 release.  The bug was fixed in 2006.06-SP1 release.  And, the
workaround was to not run "simplify_constants -boundary" command before
compile_ultra.

    - Akhil Bagri
      Synopsys, Inc.                             Mountain View, CA

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From: Linming Jin <ljin=user domain=brocade not calm>
To: John Cooley <jcooley=user domain=zeroskew not calm>

Hi, John,

I was concerned about this bad logic "ghost" DC bug.  Here is the response
from my Synopsys AE.

    - Linming Jin
      Brocade Communications                     San Jose, CA

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From: John Cooley <jcooley=user domain=zeroskew not calm>
To: Linming Jin <ljin=user domain=brocade not calm>

Hi, Linming,

Thanks for forwarding the follow-ups on this.  It's good to know that it's
an old DC bug plus to have its workaround!

    - John Cooley
      ESNUG/DeepChip.com                         Holliston, MA