Method and apparatus for automatic relative placement generation for clock trees

1. A system for circuit design, comprising:

an EDA system performing a transformation of a hardware description language circuit representation into a physical circuit representation with a clock tree of clock network flip-flops,

wherein the EDA system complies with a plurality of sets of rules created at different times, and

wherein the EDA system adds clock network buffer circuitry, including an instance with the clock network flip-flops having integrated clock gating,

wherein the system automatically creates the clock network flip-flops after coarse placement and before clock tree synthesis.

2. The system of claim 1 , wherein the plurality of sets of rules includes:

a first set of rules guiding coarse placement during the transformation specifically and automatically for a set of circuit elements in a netlist during the transformation including clock network flip-flops, the first set of rules specifying positioning of each circuit element of the set of circuit elements relative to other circuit elements of the set of circuit elements; and

a second set of rules guiding placement of the clock network flip-flops after the coarse placement and before clock tree synthesis.

3. The system of claim 1 , wherein the system automatically creates the clock network flip-flops after coarse placement and before clock tree synthesis based on clock sinks.

4. The system of claim 2 , wherein the system automatically groups the clock network flip-flops into a plurality of flip-flop groups after coarse placement and before clock tree synthesis.

5. The system of claim 4 , wherein the second set of rules are based on the plurality of flip-flop groups.

6. The system of claim 4 , wherein the system performs clock tree clustering that automatically groups the clock network flip-flops into the plurality of flip-flop groups.

7. The system of claim 6 , wherein the system performs the clock tree clustering without creating clock network buffer circuitry.

8. The system of claim 6 , wherein the second set of rules are based on the plurality of flip-flop groups from the clock tree clustering.

9. The system of claim 5 , wherein the system automatically creating clock network buffer circuitry for the plurality of flip-flop groups during the placement after the coarse placement.

10. The system of claim 6 , wherein the system automatically creating clock network buffer circuitry for the plurality of flip-flop groups during the placement after the coarse placement, the clock network buffer circuitry matched to the grouped clock network flip-flops in the circuit design.

11. The system of claim 2 , wherein the clock network flip-flops are leaf nodes of a clock tree.

12. The system of claim 1 , wherein the plurality of sets of rules obey clock tree constraints.

13. A tangible non-transitory computer readable medium with computer readable instructions executable by a computer system, comprising:

instructions executable by the computer system to transform a hardware description language circuit representation into a physical circuit representation with a clock tree of clock network flip-flops,

wherein the instructions comply with a plurality of sets of rules created at different times, and

wherein the instructions add clock network buffer circuitry, including an instance with the clock network flip-flops having integrated clock gating,

wherein the computer system automatically creates the clock network flip-flops after coarse placement and before clock tree synthesis.

14. The tangible non-transitory computer readable medium of claim 13 , wherein the plurality of sets of rules includes:

a first set of rules guiding coarse placement during the transformation specifically and automatically for a set of circuit elements in a netlist during the transformation including clock network flip-flops, the first set of rules specifying positioning of each circuit element of the set of circuit elements relative to other circuit elements of the set of circuit elements; and

a second set of rules guiding placement of the clock network flip-flops after the coarse placement and before clock tree synthesis.

15. The tangible non-transitory computer readable medium of claim 1 , wherein the computer system automatically creates the clock network flip-flops after coarse placement and before clock tree synthesis based on clock sinks.

16. The tangible non-transitory computer readable medium of claim 14 , wherein the computer system automatically groups the clock network flip-flops into a plurality of flip-flop groups after coarse placement and before clock tree synthesis.

17. The tangible non-transitory computer readable medium of claim 16 , wherein the second set of rules are based on the plurality of flip-flop groups.

18. The tangible non-transitory computer readable medium of claim 16 , wherein the computer system performs clock tree clustering that automatically groups the clock network flip-flops into the plurality of flip-flop groups.

19. The tangible non-transitory computer readable medium of claim 18 , wherein the computer system performs the clock tree clustering without creating clock network buffer circuitry.

20. The tangible non-transitory computer readable medium of claim 18 , wherein the second set of rules are based on the plurality of flip-flop groups from the clock tree clustering.

21. The tangible non-transitory computer readable medium of claim 17 , wherein the computer system automatically creating clock network buffer circuitry for the plurality of flip-flop groups during the placement after the coarse placement.

22. The tangible non-transitory computer readable medium of claim 18 , wherein the computer system automatically creating clock network buffer circuitry for the plurality of flip-flop groups during the placement after the coarse placement, the clock network buffer circuitry matched to the grouped clock network flip-flops in the circuit design.

23. The tangible non-transitory computer readable medium of claim 14 , wherein the clock network flip-flops are leaf nodes of a clock tree.

24. The tangible non-transitory computer readable medium of claim 13 , wherein the plurality of sets of rules obey clock tree constraints.