Abstract: A hierarchical method of legalizing the placement of logic cells in the presence of blockages selectively classifies the blockages into at least two different sets based on size (large and small). Movable logic cells are relocated first among coarse regions between large blockages to remove overlaps among the cells and the large blockages without regard to small blockages (while satisfying capacity constraints of the coarse regions), and thereafter the movable logic cells are relocated among fine regions between small blockages to remove all cell overlaps (while satisfying capacity constraints of the fine regions). The coarse and fine regions may be horizontal slices of the placement region having a height corresponding to a single circuit row height of the design. Cells are relocated with minimal perturbation from the previous placement, preserving wirelength and timing optimizations. The legalization technique may utilize more than two levels of granularity with multiple relocation stages.

Abstract: A method and system for concurrent buffering and layer assignment in integrated current layout. Buffers are inserted and metal interconnects or “wires” are sized for every net, which consists of one driver and one or more receivers, such that timing skew constraints can be met. Long nets are promoted to a higher level if the slew violation can be fixed only by a promotion of the net or if the “slack” gain available by this promotion is equal to or greater than a predesignated layer of promotion threshold. In response to determining these layer assignments, the method and system then systematically demotes nets that are not critical and which do not impact the circuit and electrical constraints in order to minimize the use of high layer wire resources.

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 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 fast technique for circuit optimization in a physical synthesis flow iteratively repeats slew-driven (timerless) buffering and repowering with a changing slew target. Buffers are added as necessary with each iteration to bring the nets in line with the new slew target, but any nets having positive slack from the previous iteration are skipped, and that slack information is cached for future timing analysis. Buffer insertion is iteratively repeated with incrementally decreasing slew until a minimum slew is reached, or when none of the nets have negative slack. Iteratively repeating the timerless buffering and repowering while gradually decreasing the slew constraint in this manner results in a design structure which retains high quality of results with significantly smaller area and wire length, and with only a small computational overhead.

Abstract: Disclosed is a computer implemented method, data processing system, and computer program product to optimize, incrementally, a circuit design. An Electronic Design Automation (EDA) system receives a plurality of nets wherein each net is comprised of at least one pin. Each pin is linked to a net to form a path of at least a first pin and a second pin, wherein the first pin is a member of a first net. The second pin can be a member of a second net, and the path is associated with a slack. The EDA system determines whether the path is a critical path based on the slack. The EDA system reduces at least one wire length of the path, responsive to a determination that the path is a critical path. The EDA system moves a non-critical component in order to reduce at least one wire length of the nets that include pins of a non-critical component, responsive to reducing at least one wire length of the path, wherein the non-critical component lacks pins on a critical path.

Abstract: The present disclosure is directed to a method for determining a plurality of buffer insertion locations in a net for an integrated circuit design. The method may comprise calculating a plurality of resistive-capacitive (RC) influences in parallel, each RC influence corresponding to one of a plurality of buffering options available for a first sub-tree for the addition of a wire segment to the first sub-tree; updating the plurality of RC influences for the addition of a buffer for the first sub-tree, the buffer comprising one of a plurality of buffer types; and merging the first sub-tree with a second sub-tree in parallel by grouping the plurality of buffering options available for the first sub-tree and a plurality of buffering options available for the second sub-tree into a plurality of merging groups, and merging at least two groups of the plurality of merging groups in parallel.

Abstract: The present disclosure is directed to a method for estimating an interconnect delay for a source-to-sink path of a net within a Very Large Scale Integration (VLSI) circuit, the source-to-sink path connecting a source and a sink in the net. The method may comprise estimating a total wire capacitance; calculating a delay contribution based on delay of the source-to-sink path and delay of a plurality of off-path sinks; and estimating the interconnect delay for the source-to-sink path based on the delay contribution.

Abstract: A method, data processing system and computer program product for optimizing the placement of logic gates of a subcircuit in a physical synthesis flow. A Pyramids utility identifies and selects movable gate(s) for timing-driven optimization. A delay pyramid and a required arrival time (RAT) surface are generated for each net in the selected subcircuit. A slack pyramid for each net is generated from the difference between the RAT surface and delay pyramid of each net. The slack pyramids are grown and tested using test points to generate a worst-case slack region based on a plurality of slack pyramids in the selected subcircuit. The worst-case slack region is mapped on a placement region and a set of coordinates representing the optimal locations of the movable element(s) in the placement region are determined and outputted.

Abstract: A method, data processing system and computer program product for optimizing the placement of logic gates of a subcircuit in a physical synthesis flow. A Path Smoothing utility identifies one or more movable gates based on at least one selection criteria. A set of legalized candidate locations corresponding to one or more identified movable gates is generated. A disjunctive timing graph based on the generated set of legalized candidate locations is then generated. An optimal location of one or more movable gate(s) is determined using a recursive branch-and-bound search and stored in the computing device.

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 hierarchical method of legalizing the placement of logic cells in the presence of blockages selectively classifies the blockages into at least two different sets based on size (large and small). Movable logic cells are relocated first among coarse regions between large blockages to remove overlaps among the cells and the large blockages without regard to small blockages (while satisfying capacity constraints of the coarse regions), and thereafter the movable logic cells are relocated among fine regions between small blockages to remove all cell overlaps (while satisfying capacity constraints of the fine regions). The coarse and fine regions may be horizontal slices of the placement region having a height corresponding to a single circuit row height of the design. Cells are relocated with minimal perturbation from the previous placement, preserving wirelength and timing optimizations. The legalization technique may utilize more than two levels of granularity with multiple relocation stages.

Abstract: A method and system for concurrent buffering and layer assignment in integrated current layout. Buffers are inserted and metal interconnects or “wires” are sized for every net, which consists of one driver and one or more receivers, such that timing skew constraints can be met. Long nets are promoted to a higher level if the slew violation can be fixed only by a promotion of the net or if the “slack” gain available by this promotion is equal to or greater than a predesignated layer of promotion threshold. In response to determining these layer assignments, the method and system then systematically demotes nets that are not critical and which do not impact the circuit and electrical constraints in order to minimize the use of high layer wire resources.

Abstract: Power, routability and electromigration have become crucial issues in modem microprocessor designs. In high performance designs, clocks are the highest consumer of power. Arranging clocking components with regularity so as to minimize the capacitance on the clock nets can help reduce clock power, however, it may hurt performance due to some loss of flexibility in physically placing those components. The present invention provides techniques to optimally place clock components in a regular fashion so as to minimize clock power within a performance constraint. A rectangular grid is created and clock distribution structures are assigned to the grid intersection points. Latches are then located around the clock distribution structures to minimize an overall distance for connections between the latches and respective clock distribution structures. The horizontal and vertical pitches of the grid may be independently adjusted to achieve a more uniform spread of the clock distribution structures.

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 method, data processing system and computer program product for optimizing the placement of logic gates of a subcircuit in a physical synthesis flow. A Pyramids utility identifies and selects movable gate(s) for timing-driven optimization. A delay pyramid and a required arrival time (RAT) surface are generated for each net in the selected subcircuit. A slack pyramid for each net is generated from the difference between the RAT surface and delay pyramid of each net. The slack pyramids are grown and tested using test points to generate a worst-case slack region based on a plurality of slack pyramids in the selected subcircuit. The worst-case slack region is mapped on a placement region and a set of coordinates representing the optimal locations of the movable element(s) in the placement region are determined and outputted.

Abstract: A method, data processing system and computer program product for optimizing the placement of logic gates of a subcircuit in a physical synthesis flow. A Path Smoothing utility identifies one or more movable gates based on at least one selection criteria. A set of legalized candidate locations corresponding to one or more identified movable gates is generated. A disjunctive timing graph based on the generated set of legalized candidate locations is then generated. An optimal location of one or more movable gate(s) is determined using a recursive branch-and-bound search and stored in the computing device.

Abstract: A timing-driven cloning method iteratively partitions sinks of the net into different sets of clusters and for each set computes a figure of merit for a cloned gate location which optimizes timing based on linear delay, that is, a delay proportional to the distance between the cloned gate location and the sinks. The set having the highest figure of merit is selected as the best solution. The original gate may also be moved to a timing-optimized location. The sinks are advantageously partitioned using boundaries of Voronoi polygons defined by a diamond region surrounding the original gate, or vice versa. The figure of merit may be for example worst slack, a sum of slacks at the sinks in the second cluster, or a linear combination of worst slack and sum of the slacks.

Abstract: A method, data processing system and computer program product for optimizing the placement of logic gates of a subcircuit in a physical synthesis flow. A Rip Up and Move Boxes with Linear Evaluation (RUMBLE) utility identifies movable gate(s) for timing-driven optimization. The RUMBLE utility isolates an original subcircuit corresponding to the movable gate(s) and builds an unbuffered model of the original subcircuit. Notably, a new optimized placement of the movable gate is yielded to optimize the timing (i.e., maximize the minimum slack) of the original subcircuit, while accounting for future interconnect optimizations. The new subcircuit containing the new optimized gate placement and interconnect optimization is evaluated as to whether a timing degradation exists in the new subcircuit. If a timing degradation exists in the new subcircuit, the RUMBLE utility can restore an original subcircuit and a timing state associated with the original subcircuit.

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.