Sharing global route topologies in detailed routing

1. A system for creating layouts of integrated circuits, the system comprising:

a memory storing computer readable instructions; and

a processor for executing the computer readable instructions to cause the system to perform:

accessing an initial layout of global wires and a congestion related metric for each net in a gate level design description of an integrated circuit, the initial layout created by a global router based on the gate level design description, the initial layout of wires specifying connections between regions on the integrated circuit;

accessing a second layout that specifies, for each net, detailed routing information including connections between specific wires in the regions of the integrated circuit, the second layout created by a detailed router based on the initial layout and including a failing net that is missing a connection in the second layout between two of the regions;

generating a list of nets with a same source region and target region in the initial layout as the failing net;

selecting a net in the list of nets;

rerouting the failing net over the selected net, the rerouting comprising the global router updating the initial layout and the detailed router updating the second layout;

updating the congestion related metric for each net in response to the global router updating the initial layout; and

causing the integrated circuit to be fabricated based at least in part on the updated initial layout and the updated second layout.

2. The system of claim 1 , wherein the selecting comprises iterating through the list of nets in an order determined by the congestion related metrics until one of a net that corrects the failing net is identified and there are no more nets in the list of nets.

3. The system of claim 1 , wherein the instructions further cause the system to compute a congestion value for each pair of adjacent regions, wherein the congestion value is input to the selecting and the rerouting.

4. The system of claim 1 , wherein the instructions further cause the system to compute a weighted congestion score as the congestion metric for each net, the computing comprising:

computing a congestion value for each pair of adjacent regions that reflects a number of connections between the pair;

computing an average of the congestion values along a path of the net from source region to target region;

computing a maximum value of the congestion values along the path of the net from the source region to the target region; and

weighting the average and maximum congestion values along with an input weight of the net to generate the weighted congestion score for the net.

5. The system of claim 1 , wherein each net has two pin connections.

6. The system of claim 1 , wherein each net has at least three pin connections.

7. The system of claim 1 , wherein the instructions further cause the system to perform:

identifying a net which causes a design rule violation for the initial layout;

generating a second list of nets with the same source region and target region in the initial layout as the identified net;

selecting a second net in the second list of nets;

rerouting the identified net over the second selected net, the rerouting comprising the global router updating the initial layout; and

updating the congestion related metric for each net in response to rerouting the identified net over the second selected net.

8. The system of claim 7 , wherein the design rule violation is selected from the group consisting of a congestion violation, a length violation, and a timing violation.

9. A computer program for creating layouts of integrated circuits, the computer program product comprising:

a tangible storage medium readable by a processor and storing instructions executable by the processor for:

accessing, using a processor, an initial layout of global wires and a congestion related metric for each net in a gate level design description of an integrated circuit, the initial layout created by a global router based on the gate level design description, the initial layout of wires specifying connections between regions on the integrated circuit;

accessing, using the processor, a second layout that specifies, for each net, detailed routing information including connections between specific wires in the regions of the integrated circuit, the second layout created by a detailed router based on the initial layout and including a failing net that is missing a connection in the second layout between two of the regions;

generating a list of nets with a same source region and target region in the initial layout as the failing net;

selecting a net in the list of nets;

rerouting the failing net over the selected net, the rerouting comprising the global router updating the initial layout and the detailed router updating the second layout;

updating the congestion related metric for each net in response to the global router updating the initial layout; and

causing the integrated circuit to be fabricated based at least in part on the updated initial layout and the updated second layout.

10. The computer program product of claim 9 , wherein the selecting comprises iterating through the list of nets in an order based on the congestion related metrics until one of a net that corrects the failing net is identified and there are no more nets in the list of nets.

11. The computer program product of claim 9 , wherein the instructions are further executable for computing a congestion value for each pair of adjacent regions, wherein the congestion value is input to the selecting and the rerouting.

12. The computer program product of claim 9 , wherein the instructions are further executable for:

identifying a net which causes a design rule violation for the initial layout;

generating a second list of nets with the same source region and target region in the initial layout as the identified net;

selecting a second net in the second list of nets;

rerouting the identified net over the second selected net, the rerouting comprising the global router updating the initial layout; and

updating the congestion related metric for each net in response to rerouting the identified net over the second selected net.