Simulation with the Vivado simulator happens in two phases:
- In the first phase, the simulator compiler xelab, compiles your HDL model into a snapshot, which is a representation of the model in a form that the simulator can execute.
- In the second phase, the simulator loads and executes (using the
xsimcommand) the snapshot to simulate the model. In Non-Project Mode, you can reuse the snapshot by skipping the first phase and repeating the second.
When the simulator creates a snapshot, it assigns the snapshot a name based on the names of the top modules in the model. However, you can override the default by specifying a snapshot name as an option to the compiler. Snapshot names must be unique in a directory or SIMSET; reusing a snapshot name, whether default or custom, results in overwriting a previously-built snapshot with that name.