Abstract: Wirelength in a net of an integrated circuit design is reduced by forming clusters of sinks to be interconnected, inserting a buffer at each cluster, and providing branch connections between clusters by connecting a sink of one cluster to a buffer of another cluster, to create a buffer tree spanning all sinks. The buffers are inserted at a point on a respective bounding box of a cluster that is closest to a source for the net. A sink that provides a branch connection to the buffer of another cluster is the closest sink to that buffer (except for those sinks in the cluster). Clusters may be formed by examining different pairs of the sinks with different bounding boxes, and identifying one of the pairs whose bounding box has a lowest half-perimeter as the best pair for clustering.

Abstract: Wirelength in a net of an integrated circuit design is reduced by forming clusters of sinks to be interconnected, inserting a buffer at each cluster, and providing branch connections between clusters by connecting a sink of one cluster to a buffer of another cluster, to create a buffer tree spanning all sinks. The buffers are inserted at a point on a respective bounding box of a cluster that is closest to a source for the net. A sink that provides a branch connection to the buffer of another cluster is the closest sink to that buffer (except for those sinks in the cluster). Clusters may be formed by examining different pairs of the sinks with different bounding boxes, and identifying one of the pairs whose bounding box has a lowest half-perimeter as the best pair for clustering.

Abstract: The illustrative embodiments provide a computer implemented method which perform cell transforms that decrease overall wire length, without degrading device timing or violating electrical constraints. The process computes delay constraint coefficients for a data set. The process performs a detailed placement transform by moving a subset of cells, making the placement legal, computing a half perimeter wire length change for each output net that is a member of the subset of nets, and computing a Manhattan distance change for each source-sink gate pair within the move cells. the process computes a weighted total wire length incremented value for the transformed data set. Further, the process continues by evaluating arrival time constraints, electrical constraints, and user configurable move limits for violations, and restoring the move cells to the original placement if a violation is found.

Abstract: A buffer insertion technique addresses slew constraints while minimizing buffer cost. The method builds initial solutions for the sinks, each having an associated cost, slew and capacitance. As a solution propagates toward a source, wire capacitance and wire slew are added to the solution. When a buffer is selected for possible insertion, the slew of the solution is set to zero while the cost of the solution is incremented based on the selected buffer and the capacitance is set to an intrinsic capacitance of the buffer. The solutions of two intersecting wire branches are merged by adding branch capacitances and costs, and selecting the highest branch slew. The solution sets are updated by disregarding solutions which have a slew component greater than a slew constraint, and any solution that is dominated by another solution is eliminated. The solution having the smallest cost is selected as the final solution.

Abstract: A computer implemented method, apparatus, and computer usable program product for modifying a circuit design are provided in the illustrative embodiments. A set of candidate areas within the circuit design is identified for making a change to the circuit design. A cost associated with each candidate area in the set of candidate areas is determined to form a set of costs. The cost associated with a candidate area is the cost of making the change to the circuit design in the candidate area. Using the set of costs, a candidate area is selected from the set of candidate areas in which to make the change to the circuit design.

Abstract: A method of force directed placement programming is presented. The method includes: assigning a plurality of objects from a cell netlist to bins; shifting the objects based on the bins; computing a magnitude of a spreading force for each object of the plurality of objects based on the shifting; sorting the objects based on the magnitude of the spreading force of the objects; selecting a subset of the sorted objects based on a threshold value indicating at least one of a top percentage, a threshold force, and a threshold value that is based on a placement congestion; adjusting the spreading force of the selected objects to be equal to a predetermined value indicating a minimum spreading force; and determining a placement of the objects based on adjusted spreading force of the selected objects.

Abstract: A buffer insertion technique addresses slew constraints while minimizing buffer cost. The method builds initial solutions for the sinks, each having an associated cost, slew and capacitance. As a solution propagates toward a source, wire capacitance and wire slew are added to the solution. When a buffer is selected for possible insertion, the slew of the solution is set to zero while the cost of the solution is incremented based on the selected buffer and the capacitance is set to an intrinsic capacitance of the buffer. The solutions of two intersecting wire branches are merged by adding branch capacitances and costs, and selecting the highest branch slew. The solution sets are updated by disregarding solutions which have a slew component greater than a slew constraint, and any solution that is dominated by another solution is eliminated. The solution having the smallest cost is selected as the final solution.

Abstract: A novel iterative latch placement scheme wherein the latches are gradually pulled by increasing attraction force until they are eventually placed next to a clock distribution structure such as a local clock buffer (LCB). During the iterations, timing optimizations such as gate sizing and re-buffering are invoked in order to keep the timing estimation accurate. By applying the iterative clock net weighting adjustment, the present invention allows tighter interaction between logic placement and clock placement which leads to higher quality timing and significant power savings.

Abstract: A computer implemented method and a computer program product which perform cell transforms that decrease overall wire length, without degrading device timing or violating electrical constraints. The process computes delay constraint coefficients for a data set. The process performs a detailed placement transform by moving a subset of cells, making the placement legal, computing a half perimeter wire length change for each output net that is a member of the subset of nets, and computing a Manhattan distance change for each source-sink gate pair within the move cells. The process computes a weighted total wire length incremented value for the transformed data set, if the move will not improve placement, the move transform is not allowed. Further, the process continues by evaluating arrival time constraints, electrical constraints and user configurable move limits for violations, restoring the move cells to the original placement if a violation is found.

Abstract: The layout of latches in a common clock domain is efficiently optimized to shrink the physical size of the domain while maintaining timing requirements. The latches are placed in a first layout preferably using quadratic placement, and a star object is built representing an interim clock structure. The latches are weighted based on wire distance from a source of the star object, and then re-placed using the weighting. The weighted placement and repartitioning may be iteratively repeated until a target number of bins is reached. The boundary of the latches in the final global placement is used to define a movebound for further detailed placement.

Abstract: A method of force directed placement programming is presented. The method includes sorting objects of a netlist for placement by magnitude of their spreading force and selecting a plurality of the objects. The method further includes waiving (or nullifying) the spreading force for the selected objects in a subsequent non-linear program solver step of the force directed placement program. The positions of the objects after the subsequent non-linear program solver step are based only on their connections to other objects in the netlist. The selected objects no longer retain their relative ordering as obtained during a previous non-linear program solve step of the force directed placement program. An alternative method of force directed placement programming is also present, which includes identifying objects from a netlist for placement that have a very high spreading force magnitude.

Abstract: A buffer insertion technique addresses slew constraints while minimizing buffer cost. The method builds initial solutions for the sinks, each having an associated cost, slew and capacitance. As a solution propagates toward a source, wire capacitance and wire slew arc added to the solution. When a buffer is selected for possible insertion, the slew of the solution is set to zero while the cost of the solution is incremented based on the selected buffer and the capacitance is set to an intrinsic capacitance of the buffer. The solutions of two intersecting wire branches are merged by adding branch capacitances and costs, and selecting the highest branch slew. The solution sets are updated by disregarding solutions which have a slew component greater than a slew constraint, and any solution that is dominated by another solution is eliminated. The solution having the smallest cost is selected as the final solution.

Abstract: A system and method for correcting electrical violations, the method including examining a plurality of nets for at least one electrical violation in a sequential order of a first output-to-input traversal, and determining a net correction in each net of the plurality of nets having an electrical violation prior to examining a next net in the sequential order of the first output-to-input traversal.

Abstract: Wirelength in a net of an integrated circuit design is reduced by forming clusters of sinks to be interconnected, inserting a buffer at each cluster, and providing branch connections between clusters by connecting a sink of one cluster to a buffer of another cluster, to create a buffer tree spanning all sinks. The buffers are inserted at a point on a respective bounding box of a cluster that is closest to a source for the net. A sink that provides a branch connection to the buffer of another cluster is the closest sink to that buffer (except for those sinks in the cluster). Clusters may be formed by examining different pairs of the sinks with different bounding boxes, and identifying one of the pairs whose bounding box has a lowest half-perimeter as the best pair for clustering.

Abstract: A method of designing the layout of an integrated circuit (IC) by deriving an analytical constraint for a cut-based placement partitioner using analytical optimization, and placing cells on the IC with the cut-based placement partitioner using the analytical constraint. Quadratic optimization may be used to determine a desired ratio of a cell area of a given partition to a total cell area (the balance parameter), and placing may be performed using multilevel bisection partitioning constrained by the balance parameter. This implementation may include a determination of an aspect ratio for an entire partitioning region of the integrated circuit, and a “center-of-mass” coordinate of the cells based on the quadratic optimization, which are then used to define a placement rectangle having the same aspect ratio, and centered on the center-of-mass coordinate. This placement rectangle is used to derive the balance parameter.

Abstract: A method of designing the layout of an integrated circuit (IC) by deriving an analytical constraint for a cut-based placement partitioner using analytical optimization, and placing cells on the IC with the cut-based placement partitioner using the analytical constraint. Quadratic optimization may be used to determine a desired ratio of a cell area of a given partition to a total cell area (the balance parameter), and placing may be performed using multilevel bisection partitioning constrained by the balance parameter. This implementation may include a determination of an aspect ratio for an entire partitioning region of the integrated circuit, and a “center-of-mass” coordinate of the cells based on the quadratic optimization, which are then used to define a placement rectangle having the same aspect ratio, and centered on the center-of-mass coordinate. This placement rectangle is used to derive the balance parameter.