You raise a good question here in your pursuit of validating the coverage of your testbench. Our team reviewed this and here are our observations and recommendations.
Design teams use coverage at RTL to determine whether they have fully tested everything. When properly enabled, HDL cosimulation with Mentor ModelSim (or Questa) may be used to evaluate HDL code coverage. This is due to ModelSim’s ability to trace line-by-line “execution” of each line of HDL during simulation and provide coverage reports.
Beyond RTL, especially in ASICs we see designers using formal equivalence checking to determine whether each incremental step toward silicon introduces changes from that RTL. There might be some amount of gate-level simulation for timing effects, but that’s not anything that coverage would help you with. Once you get through the equivalence check after place & route, you build the bitstream and burn it to the device.
Our current FPGA-in-the-Loop support cannot support coverage at this level, though, because the RTL HDL is compiled into a netlist using third-party synthesis and place & route tools. Once a design has been rendered into this form, though, we would have no comparable ability to monitor execution from MathWorks products.
That said, there are other forms of validation that might be performed within FPGA vendor tools – for instance, “toggle coverage” and other forms of “stuck at” analysis could be performed by manipulating JTAG scan chains. These forms of validation are tests of manufacturing defects or failures such as those induced by exposure to radiation. Your FPGA vendor would be the appropriate source of information on such tests.
If you are interested in probing internal signals within the FPGA implmentation -- which would be more of a debug activity -- we'd suggest that you look at HDL Verifier's FPGA Data Capture capabilities to see whether they would be of interest.
All that said, it’s possible we’ve misinterpreted your post, so we would like to follow up with you through your local account team to make certain we’ve addressed your areas of concern.
Thank you for posting this,