How can I debug a delta count overflow?

Solution

A delta count overflow usually means that there is a combinatorial feedback loop within your design. For example:

B <= not A;
A <= B;

If the loop is intentional, at least one delay needs to be added somewhere within the chain. If it is not intentional, please try the following:

1. Analyze the process statement mentioned in the printed error message

2. Run the simulation to the moment just before the time reported in the message, and single-step through the code to identify the lines that are executed repeatedly

3. Use the Advanced Dataflow to graphically locate the loop

4. Run the simulation with Code Coverage and check the coverage report to identify the most frequently executed lines