Method and Apparatus for Using Connection Graphs with Potential Diagonal Edges to Model Interconnect Topologies During Placement
0 Assignments
0 Petitions
Accused Products
Abstract
The invention is directed towards method and apparatus that consider diagonal wiring in placement. Some embodiments of the invention are placers that use diagonal lines in calculating the costs of potential placement configurations. For instance, some embodiments estimate the wirelength cost of a placement configuration by (1) identifying, for each net in a net list, a bounding box that encloses all the circuit elements of the net, (2) computing an attribute of each bounding box by using a line that can be completely or partially diagonal, and (3) computing the wirelength cost estimate based on the computed attributes. To estimate the wirelength cost of different placement configurations, other embodiments construct connection graphs that model the net interconnect topologies. These connection graphs can have edges that are completely or partially diagonal. Other embodiments use diagonal lines to measure congestion costs of potential placement configurations. For instance, some placers use diagonal lines as cut lines that divide the IC layout into regions. These placers then generate congestion-cost estimates by measuring the number of nets cut by the diagonal cut lines.
109 Citations
96 Claims
-
1-42. -42. (canceled)
-
43. A computer readable medium that stores a computer program that places circuit modules in an integrated circuit (“
- IC”
) layout, wherein said IC layout includes a net and a plurality of circuit elements, wherein the net represents interconnections between a set of circuit elements, the computer program comprising sets of instructions for;
constructing a connection graph that models the topology of interconnect lines for connecting the circuit elements of the net, wherein said connection graph having edges, each edge connecting two circuit elements of the net, wherein at least one of the edges is at least partially diagonal, identifying a placement metric based on the connection graph. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 54, 55, 56, 57)
- IC”
-
53. The computer readable medium of clam 43, wherein the diagonal edge forms a 120°
- angle with respect to a side of the IC layout.
-
58. A computer readable medium that stores a computer program that places circuit modules in an integrated circuit (“
- IC”
) layout, wherein said IC layout includes a plurality of nets each of which includes a plurality of circuit elements in the IC layout, wherein the computer program uses a wiring model that defines different types of interconnect lines for connecting the circuit elements of the nets, said wiring model having diagonal lines, the computer program comprising sets of instructions for;
a) defining, for each particular net, a minimum spanning tree that models the topology of interconnect lines for connecting the circuit elements of the particular net, said minimum spanning trees having edges, wherein at least one of the edges of at least one of the minimum spanning trees is at least partially diagonal, b) calculating the length of the edges of the minimum spanning trees; and
c) combining the length calculations to obtain an estimate of the total interconnect-line length needed for connecting the circuit elements of the nets. - View Dependent Claims (59, 60)
- IC”
-
61. A computer readable medium that stores a computer program that places circuit modules in an integrated circuit (“
- IC”
) layout, wherein said IC layout includes a plurality of nets each of which includes a plurality of circuit elements in the IC layout, wherein the computer program uses a wiring model that defines different types of interconnect lines for connecting the circuit elements of the nets, said wiring model having diagonal lines, the computer program comprising sets of instructions;
a) defining, for each particular net, a Steiner tree that models the topology of interconnect lines for connecting the circuit elements of the particular net, said Steiner trees having edges, wherein at least one of the edges of at least one of the Steiner trees is at least partially diagonal;
b) calculating the length of the Steiner trees; and
c) combining the length calculations to obtain an estimate of the total interconnect-line length needed for connecting the circuit elements of the nets. - View Dependent Claims (62, 63, 64)
- IC”
-
65-87. -87. (canceled)
-
88. A computer readable medium that stores a computer program that places circuit modules in an integrated circuit (“
- IC”
) layout, wherein said IC layout includes a set of circuit elements, the computer program comprising sets of instructions for;
a) identifying a connection graph that models the topology of interconnect lines for connecting the set of circuit elements, wherein said connection graph has a plurality of edges, wherein at least some of the edges are neither parallel nor orthogonal to each other, b) identifying a placement metric based on the connection graph. - View Dependent Claims (89, 90, 91, 92, 95, 96)
- IC”
-
93. The computer readable medium of clam 88, wherein the edges that are neither parallel nor orthogonal forms a 45°
- angle with respect to each other.
-
94. The computer readable medium of clam 88, wherein the edges that are neither parallel nor orthogonal forms a 120°
- angle with respect to each other.
Specification