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report_timing issue

meds7

Dear all,


I am using multimode analysis views for creation of multi corner timing info in my .sdf file.

After setting the analysis view and trying to report timing with the 'report_timing' command in encounter I see that no delays are used for my clock tree. It is only the clock tree timing info which is missing in the timing reports. All other delays are present.

Does anybody know what I am doing wrong?

regard

Henk

  • sounds like your clocks are not propagated
  • Hi Kari, thanks for your response. I hope you can help me a little bit further. How do I force propagated clocks? Do i need to use the set_propagated_clocks command? I tried that but it informs me that this is not allowed in interactive mode....
  • It's been a while since i've dealt with clocks and constraints, but i think there are a few ways you can do it. you can use set_interactive_constraint_modes to the analysis view you want (but ideally all of them), then issue the set_propagated_clock command. Or, you can have two sets of SDC files (constraints): one "ideal", like you already have, and another "propagated" which contain the set_propagated_clock statement(s). Then you use the propagated version of the SDCs after your clock trees are built. However, I thought that when going through the design flow in EDI, once clock trees were in, then clocks would automatically be propagated, but like I said it's been a while since I did this, and I also don't know anything about your flow. Hope that helps!

  • Hi Kari,

    Maybe I am using MMMC wrong.

    My flow uses the default_mode_setup and default_mode_hold constraints which are created by the tool (of course based on my sdc constraints).

    I just wanted to generate one additional corner (typical 25 degree corner) to the results in my generated sdf file. Therefore I added one additonal rc corner, a delay corner and a typical constraint mode in order to create the typical new analysis view for 25 degrees.

    Then I generate the layout with clocktree and at the end the timing reports are correctly generated as a result of the optDesign command I believe.

    At that point I can see all correct timing info in the reports including delays inside the clock tree.

    At the end of my script where I want to generate the sdf file I set my analysis views again with this command:

    set_analysis_view -setup {default_view_hold typical_view default_view_setup} -hold {default_view_hold typical_view default_view_setup}

    after which I generate the sdf with write_sdf

    However, from that point when I type report_timing from the prompt I get a report which does not involve the clocktree delays anymore.

    Interactive constraint mode does not seem to be possible at that poinr because I am using the default_view_setup and the default_view_hold.

    Therefore, I still don't understand now where I went wrong...

    regards

  • Hi Kari,

    Maybe I am using MMMC wrong.

    My flow uses the default_mode_setup and default_mode_hold constraints which are created by the tool (of course based on my sdc constraints).

    I just wanted to generate one additional corner (typical 25 degree corner) to the results in my generated sdf file. Therefore I added one additonal rc corner, a delay corner and a typical constraint mode in order to create the typical new analysis view for 25 degrees.

    Then I generate the layout with clocktree and at the end the timing reports are correctly generated as a result of the optDesign command I believe.

    At that point I can see all correct timing info in the reports including delays inside the clock tree.

    At the end of my script where I want to generate the sdf file I set my analysis views again with this command:

    set_analysis_view -setup {default_view_hold typical_view default_view_setup} -hold {default_view_hold typical_view default_view_setup}

    after which I generate the sdf with write_sdf

    However, from that point when I type report_timing from the prompt I get a report which does not involve the clocktree delays anymore.

    Interactive constraint mode does not seem to be possible at that poinr because I am using the default_view_setup and the default_view_hold.

    Therefore, I still don't understand now where I went wrong...

    regards

  • I think you need to add the set_propagated_clock command to your SDC file(s). When you re-issue the set_analysis_view command, everything is reset to the associated SDCs. Previous to that, I think the tool understood that your clocks were propagated.

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