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mukesh_patel
Participant
Participant
482 Views
Registered: ‎10-11-2017

Combinatorial Loop

Hi 

I am working on complex project, I generated bitfile , bitfile got generated with a lot of slacks. When I look into implementation log I found around 100+ combinatorial  loop found in Log file , but in implementation design timing report summary loops are 0.

So I want to ask which combinatorial loop I have to consider?

 

Regards,

Mukesh

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5 Replies
calibra
Scholar
Scholar
457 Views
Registered: ‎06-20-2012

You MUST remove ALL combinatorial loop.

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mukesh_patel
Participant
Participant
379 Views
Registered: ‎10-11-2017

Right All combinatorial loop needs to remove.

Can any one suggest how to remove combinatorial loop using constraints only?

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drjohnsmith
Teacher
Teacher
363 Views
Registered: ‎07-09-2009

Combinational loops

  are not caused by the tools, but by your code,

Sorry, but when you simulated, this should have been fairly obvious report.

 

a constraint can not tell your code where to break a loop

   

 

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u4223374
Advisor
Advisor
312 Views
Registered: ‎04-26-2015

If the code actually built successfully despite combinatorial loops being reported early in the build, that most likely means that the tools have made some major optimisations which removed the loops completely (eg. output was never used). You should have a hunt for the warnings about that...

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calibra
Scholar
Scholar
278 Views
Registered: ‎06-20-2012

Look for latchs on the synthesis process.

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