Warning: Cannot trace SLP signal <signal_name> in standard Waveform module. Please use Accelerated Waveform Viewer instead.


I received the above error when I initialize the simulation and add signals to the Standard Waveform Viewer. If I continue and run the simulation, question marks are displayed instead of the correct signal values. What am I doing wrong?


The Standard Waveform Viewer does not support Verilog optimized (SLP) signals. If you want to use Verilog optimization, you need to use the Accelerated Waveform Viewer. If you want to use Standard Waveform Viewer, then you need to disable the Verilog optimization.

  1. You have the Verilog Optimization enabled. To disable:

    If you use GUI:

    • Go to Design | Settings

    • In the Simulation category, select Verilog and uncheck the Verilog Optimization option.

      If you use batch mode/script:

    • Please use switch -o2 r for asim command:

      asim -o2 ....
  2. If you want to use the Verilog Optimization:

    • You will need to switch from the Standard Waveform Viewer to the Accelerated Waveform Viewer.

    • Go to Tools | Preferences

    • In the Editors category, select Waveform Viewer/Editor, and select Accelerated Waveform Viewer as the default from the drop-down box.

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