combinational loops as latches

Thanks for all your help. However, I have checked very carefully, and, actually, I use "<=" instead of "=" whenever I could (I have used many always blocks for the updates). Besides, I use intermediate variables (wire types) outsides the always loops for the calculations before the next rising edge of the clock so that the registers' input values could be updated quickly at the posedge of clock. I really couldn't see any pure combinational loops. Is there a way the tool could tell me what the combinational loops are corresponding to the warning? This warning is very brief and doesn't have any specific details. Thanks