6912 - Diamond: How to avoid optimization of inputs or nets during synthesis?

6912 - Diamond: How to avoid optimization of inputs or nets during synthesis?

Description:
For keeping the nets during synthesis or in mapping process, 
the user can use the attribute /* synthesis syn_keep=1 nomerge="on"*/ on the nets or other signal wanted to retain. 
 
Solution:
Verilog example: 
input wire A /* synthesis syn_keep=1 NOMERGE="ON" */ 
 
VHDL example:
attribute syn_keep : boolean;
attribute syn_keep of A: signal is true;
attribute nomerge : string;
attribute nomerge of A: signal is "ON";