is maintained in a much cleaner state than otherwise thereby creating a more efficient environment for identifying and removing defects in the design application_number US 5774208 A description while the present invention will be described more fully hereinafter with reference to the accompanying drawings in which a preferred embodiment of the present invention is shown it is to be understood at the outset of the description which follows that persons of skill in the appropriate arts may modify the invention here described while still achieving the favorable results of the invention accordingly the description which follows is to be understood as being a broad teaching disclosure directed to persons of skill in the appropriate arts and not as limiting upon the present invention turning now to the drawings in greater detail it will be seen that in fig1 there are three layers in the regression system of the present invention updates to simulation code indicated at 11 or to the hdl design indicated at 12 must progress to layer 3 in order to be considered part of general regression as changes are committed to the simulation code base and to the hdl design and introduced to layer 1 routine checks are performed to ensure that the resulting code and model can compile without error if this step is successful the code and logic are checkpointed for possible restart in a future self healing action as described hereinafter if the latest code or model fails during compilation in this.