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AR# 5249

SYNPLIFY: How to preserve a signal through synthesis using the syn_keep attribute?


General Description: How to preserve a signal or wire through Synplify,

so it does not get optimized?

The syn_keep attribute is declared on a wire or signal. This attribute

preserves the specified wire through synthesis and prevents it from

being optimized out in the final design.

NOTE: Use Synplify 5.0.8 or greater.




library synplify;

use synplify.attributes.all;

entity example is

port ( <port list> )

end entity;

architecture XILINX of example is

signal temp : bit_vector (7 downto 0);

attribute syn_keep of temp : signal is true;



module example (<port list>);

wire [7:0] temp /* synthesis syn_keep = 1 */;
AR# 5249
Date Created 08/31/2007
Last Updated 05/16/2011
Status Archive
Type General Article