General Description: A design that ran successfully in the 3.1i tools fails in the 4.1i tools due to a lost connection. The discrepancy occurs because of a difference in the way the two EDIF readers handle an unusual construct in the EDIF file. So far, this construct has only been seen in EDIF files written by an application named "CoreFire" from Annapolis Microsystems.
In this case, the EDIF file specifies that a single port is connected to two different nets. The 3.1i EDIF reader merges the two nets, while the 4.1i EDIF reader overrides the first net connection with the second. Generally, the symptom of this problem is lost connectivity. In specific cases, errors similar to the following are reported:
"ERROR:MapLib:32 - LUT2 symbol "u1/u_ResponseToPdrSou/u_BitwiseLUT2_INIT/u_LUT2" (output signal=u1:src_push) has an equation that uses an input pin connected to a trimmed signal. Make sure that all the pins used in the equation for this LUT have signals that are not trimmed. (See trim report for details on which signals were trimmed)."
NOTE: In most cases, this error message is an indication of design problems that are resulting in valid trimming. If your case does not match all of the characteristics stated above, the issue is probably design related.