User guide

14-13
Negative Timing Checks
delayed_data_signal
The name of the delayed version of the data signal, typically a
clock signal.
Enabling Negative Timing Checks
To use a negative timing check you must include the +neg_tchk
compile-time option when you compile your design. If you omit this
option, VCS changes all negative limits to 0.
If you include the +no_notifier compile-time option with the
+neg_tchk option, you only disable notifier toggling. VCS still
creates the delayed versions of the reference and data signals and
displays timing violation messages.
Conversely, if you include the +no_tchk_msg compile-time option
with the +neg_tchk option, you only disable timing violation
messages. VCS still creates the delayed versions of the reference
and data signals and toggles notifier regs when there are timing
violations.
If you include the +neg_tchk compile-time option but also include
the +notimingcheck or +nospecify compile-time options, VCS
does not compile the $setuphold and $recrem timing checks into
the simv executable. However, it does create the signals that you
specified in the delayed_reference_signal and
delayed_data_signal arguments, and you can use these to drive
sequential devices in the cell. Note that there is no delay on these
"delayed" and they have the same transition times as the signals
specified in the reference_event and data_event arguments.