How to check signal waveform.

For functional sims, use pre-synthesis. For timing use post-fit. THe other ones work too. For example, if you choose post-fit and select a register, and that node name exists in the pre-synthesis, it will use it in the functional simulation. Worst thing that happens is you choose a node that doesn't exist in your simulation and have to go back and find one that does. You'll quickly get an understanding of what's available.