User guide

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VPD and EVCD File Generation
• Saving statement execution for an entire design can increase
simulation time by eight times or more. To limit performance
degradation, limit the use of statement saves to certain scopes.
Instead of saving statement execution from time 0, turn on tracing
just prior to the time of a suspected problem and off after that time.
• The file size increases from 200 to 500 percent when saving line
execution data.
• Glitch detection and delta cycle may significantly increase the size
of the VPD file.
• The +vpdports option costs some CPU time and memory in the
initialization. It allows telling ports from internal signals in the
hierarchy browser.
• The +vpddrivers option costs some CPU time and memory
during the simulation. However, it allows visibility to the individual
values of drivers of a multiply driven net.
• You can use the +vpdfilesize option (file wrap) in a verification
environment where stimuli are automatically generated or read
and the results are verified by the testbench. Then, you can stop
the simulation when an error occurs, and the required history data
will remain even in the relatively small file that is left.