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Prevent OptDesign in between paths

dinac123

I am trying to prevent Optimization between a path. 

set_dont_touch, works only for the complete net, but not between a begin pin to a End Pin.

Is there any other option to achieve this type ofcontraints?

Thank You 

  • ajay01

     Hi dinac123,

    use below command:

    set_false_path -from beginpin -to endpin

     

  • dinac123

    That will not work. set_false_path is only to ignore paths for the timing engine and would still add optimization buffer in the path.

    I think there is no option availabe to do this. For now only trick, I found is to add Fence. [ running with setOptMode -honorFence true , prevent

    addtion of buffer under this region, and hence force encounter to buffer after/outer ] 

  • ajay01
    fence will work for a module or group not for path..........
  • skmhs PD
    you'd need to develop a Tcl script to obtain all net names along the path then set_dont_touch.
  • dinac123

    yes, set_dont_touch would work for the nets.

    In my case, for example U1/a is connect with N1 to U2/a, U3/a,U4/a.

    I want no optimization buffers only for the path U1/a to U3/a  

  • skmhs PD
    That doesn't quite make sense. Are you talking about setup or hold opt? And what's the reason behind this requirement?

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