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Newbie irun2
Newbie
2,994 Views
Registered: ‎08-05-2013

How to prevent the mapper to remove logics?

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My design has some delay cells building up with several BUF primitives. At the end of every instance line I've put (*KEEP = "TRUE" *), and synthesis report shows:

    Set user-defined property "KEEP =  TRUE" for instance <dly_loop[0].buf_gen> in unit <delay>.

This makes me believe the KEEP attribute has take effect...

 

But in the implementation stage, *mapper* considered the BUFs are redundant and removed them all. I've tried almost every option in the map properties, the result is the same.

Section 5 - Removed Logic
-------------------------

Redundant Block(s):
TYPE 		BLOCK
LUT1 		dly7/buf_head
LUT1 		dly7/dly_loop[0].buf_gen

 

Is there any way to prevent the tool doing so?

 

Thanks!

 

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Xilinx Employee
Xilinx Employee
3,766 Views
Registered: ‎07-23-2012

Re: How to prevent the mapper to remove logics?

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Hi,

Please try the save attribute to prevent any ent from getting trimmed during implementation. Refer to page no 245 of http://www.xilinx.com/support/documentation/sw_manuals/xilinx14_2/cgd.pdf .

The attribute keep is syntheis only attribute hence it doesn't have any impact during implementation.

Regards,
Krishna
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Xilinx Employee
Xilinx Employee
3,767 Views
Registered: ‎07-23-2012

Re: How to prevent the mapper to remove logics?

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Hi,

Please try the save attribute to prevent any ent from getting trimmed during implementation. Refer to page no 245 of http://www.xilinx.com/support/documentation/sw_manuals/xilinx14_2/cgd.pdf .

The attribute keep is syntheis only attribute hence it doesn't have any impact during implementation.

Regards,
Krishna
-----------------------------------------------------------------------------------------------
Please mark the post as "Accept as solution" if the information provided answers your query/resolves your issue.

Give Kudos to a post which you think is helpful.
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Newbie irun2
Newbie
2,984 Views
Registered: ‎08-05-2013

Re: How to prevent the mapper to remove logics?

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It works, thanks a lot!
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