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 How to force RTL compiler to use a particular net name 

Last post Thu, Dec 1 2011 12:52 AM by deeps4. 3 replies.
Started by deeps4 30 Nov 2011 06:45 AM. Topic has 3 replies and 3871 views
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  • Wed, Nov 30 2011 6:45 AM

    • deeps4
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    • Joined on Thu, Jul 29 2010
    • Posts 12
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    How to force RTL compiler to use a particular net name Reply

     Hi,

    I have a RTL which after synthesis looks as in  the snippet  mentioned below..

     ===================================

    wire [2:0] seed_inp;
     wire [2:0] seed_outp;

    output[2:0] seed_outp;

      wire scan_5_q, scan_9_q, scan_10_n_0, scan_10_q, scan_11_n_0,
           scan_11_q, scan_12_n_0, scan_12_q;
      wire scan_fix0_6_n_0, scan_fix0_6_n_1, scan_fix0_6_q,
           scan_fix0_8_n_6, scan_fix0_8_n_8, scan_fix0_8_n_14,
           scan_fix1_2_n_0, scan_fix1_2_q;
      df1qpdw scan_10_q_reg(.CP (clk), .D (scan_10_n_0), .Q (scan_10_q));
      mx21x2pdw scan_10_g22(.D0 (seed_inp[2]), .D1 (scan_10_q), .S0
           (scan), .Z (scan_10_n_0)); 

    ....

    .....

    ==================================================

    I wanted RTL compiler to take the above sinppet as

    df1qpd scan_8_q_reg(.CP (clk), .D (seed_outp[2]), .Q (scan_8_q)); 

    mx21x2pd scan_8_g20(.D0 (seed_inp[2]), .D1 (scan_8_q), .S0
           (scan), .Z (seed_outp[2]));

    ==================================================

    Functionality wise both are same but I am getting unnconnected  in the netlist because of this issue..

     wire [2:0] seed_inp;
     wire [2:0] seed_outp;

    Is as written in the RTL and scan_9* scan_10* etc are as written out by RTL compiler after synthesis.

    Is there a way I can force the RTL compiler not to use its own wire names but to retain the wire names as written in RTL ?

     

    Regards,

    -DN

    • Post Points: 20
  • Wed, Nov 30 2011 6:55 AM

    • grasshopper
    • Top 25 Contributor
    • Joined on Fri, Jul 18 2008
    • Chelmsford, MA
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    Re: How to force RTL compiler to use a particular net name Reply

     Hi DN,

     I believe you are looking for this

       attribute name: write_vlog_preserve_net_name
              category: write (controls write output)
           object type: root
           access type: read-write
             data type: boolean
         default value: false
                  help: Determines whether to preserve net names present in user input or not.

    Note that dangling wires resulting in incorrectly implemented functionality would be a bug in the tool. Did you run LEC ? I suspect if the wire became unconnected it probably could be optimized out but obviously I have no knowledge of RTL or functionality

     

    gh-

     

    • Post Points: 20
  • Wed, Nov 30 2011 9:00 PM

    • deeps4
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    Re: How to force RTL compiler to use a particular net name Reply

     Hi gh,

    I could not find that command in the manual. But some how that also did not help. May be I will try different version of RTL compiler and check.

    Thanks,

    DN

     

     

    • Post Points: 5
  • Thu, Dec 1 2011 12:52 AM

    • deeps4
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    • Joined on Thu, Jul 29 2010
    • Posts 12
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    Re: How to force RTL compiler to use a particular net name Reply

     Hi gh,

    The signal was getting optimized out. I have one generic question to you. How does these unconnected or optimised nets gets handled

     during PNR. I mean if the gate levels has few ports as "unconnected" how does this gets sorted out during further stages, will it be tied off?

     

    Regards,

    -DN

     

    • Post Points: 5
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Started by deeps4 at 30 Nov 2011 06:45 AM. Topic has 3 replies.