Abstract: A computer implemented method, data processing system, and computer program product for reworking a plurality of cells initially placed in a circuit design. An expander allocates cells to tiles. The expander determines a high detailed routing cost tile class, wherein the high detailed routing cost tile class is a class of tiles that has high detailed routing costs. The expander selects a cell within a tile of the high detailed routing cost tile class to form a selected cell in a selected tile. The expander applies multiple techniques to reposition these cells at new locations to improve the detailed routability. The expander can place an expanded bounding box around the selected cell, wherein the bounding box extends to at least one tile adjacent the selected tile, and repositions the selected cell within the bounding box to form a modified design to improve the detailed routability. The expander may also inflate and legalize those cells.

Abstract: A computer implemented method, data processing system, and computer program product for reworking a plurality of cells initially placed in a circuit design. An expander allocates cells to tiles, wherein some tiles have cells. The expander determines a high detailed routing cost tile class, wherein the high detailed routing cost tile class is a class of tiles that are high detailed routing cost tiles. The expander selects a cell within a tile of the high detailed routing cost tile class to form a selected cell and a selected tile. The expander places an expanded bounding box around the selected cell, wherein the bounding box extends to at least one tile adjacent the selected tile. The expander expands the selected cell within the bounding box to form a modified design, determines an aggregate routing cost among other steps, and affirms the modified design for further processing.

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: A method, system, and computer program product for whitespace creation and preservation in the design of an integrated circuit (IC) are provided in the illustrative embodiments. A first estimate is formed by estimating an amount of whitespace that is needed to reduce a congestion value of a congested area of the design to a threshold value. A set of virtual filler cells is added to the congested area, wherein adding the set of virtual filler cells does not add actual whitespace cells to the congested area but reduces the congested area by at least the first estimate. A virtual filler cell in the set of virtual filler cells is replaced with a corresponding real filler cell. A determination is made whether the design has improved. A final placement solution is created when the design has not improved.

Abstract: Scheduling of parallel processing for regionally-constrained object placement selects between different balancing schemes. For a small number of movebounds, computations are assigned by balancing the placeable objects. For a small number of objects per movebound, computations are assigned by balancing the movebounds. If there are large numbers of movebounds and objects per movebound, both objects and movebounds are balanced amongst the processors. For object balancing, movebounds are assigned to a processor until an amortized number of objects for the processor exceeds a first limit above an ideal number, or the next movebound would raise the amortized number of objects above a second, greater limit. For object and movebound balancing, movebounds are sorted into descending order, then assigned in the descending order to host processors in successive rounds while reversing the processor order after each round. The invention provides a schedule in polynomial-time while retaining high quality of results.

Abstract: An automated method and apparatus for positioning gate array circuits in an integrated circuit design. An initial integrated circuit design includes logic cells and gate array fill circuits positioned thereon. The gate array fill circuits are positioned in available space between the adjacent logic cells so as to fill the available space with the maximum gate array fill circuits. A gate array logic element to be positioned in the integrated circuit design, such as may be required by an engineering change to the circuit design, is automatically positioned between adjacent logic cells so as to allow for full utilization of any space remaining between the adjacent logic cells by gate array fill circuits.

Abstract: Scheduling of parallel processing for regionally-constrained object placement selects between different balancing schemes. For a small number of movebounds, computations are assigned by balancing the placeable objects. For a small number of objects per movebound, computations are assigned by balancing the movebounds. If there are large numbers of movebounds and objects per movebound, both objects and movebounds are balanced amongst the processors. For object balancing, movebounds are assigned to a processor until an amortized number of objects for the processor exceeds a first limit above an ideal number, or the next movebound would raise the amortized number of objects above a second, greater limit. For object and movebound balancing, movebounds are sorted into descending order, then assigned in the descending order to host processors in successive rounds while reversing the processor order after each round. The invention provides a schedule in polynomial-time while retaining high quality of results.

Abstract: Assigning pins to macro-blocks of an Integrated Circuit (IC) chip is described. The macro-block pin assignments are automatically placed using Constraint Programming (CP) techniques to position the pins on the periphery of a macro-block. Bus-ordering and pin-spacing constraints are performed considering all the nets forming the IC design simultaneously. The CP formulation includes modeling detailed and discrete constraints required to achieve an optimal pin-assignment. A stochastic CSP solver is used to define the cost function on search points giving full assignments to all the variables. The macro-block pins are ultimately moved to computed locations.

Abstract: A global placer receives a plurality of regions, each region occupying a sub-area of a design area. receives a plurality of movebound objects, each movebound object associated with a region. The global placer receives a plurality of unconstrained objects, each unconstrained object associated with no region. The global placer receives a tolerance, wherein the placement tolerance defines a coronal fringe to at least one region. The global placer initially placing the plurality of movebound objects and unconstrained objects. The global placer iterates over objects without preference to region-affiliation to select an object, wherein the objects are comprised of the plurality of movebound objects and plurality of unconstrained objects. The global placer determines whether movebound object is within the tolerance of a region associated with the movebound object.

Abstract: Assigning pins to macro-blocks of an Integrated Circuit (IC) chip is described. The macro-block pin assignments are automatically placed using Constraint Programming (CP) techniques to position the pins on the periphery of a macro-block. Bus-ordering and pin-spacing constraints are performed considering all the nets forming the IC design simultaneously. The CP formulation includes modeling detailed and discrete constraints required to achieve an optimal pin-assignment. A stochastic CSP solver is used to define the cost function on search points giving full assignments to all the variables. The macro-block pins are ultimately moved to computed locations.

Abstract: A computer implemented method, data processing system, and computer program product for reworking a plurality of cells initially placed in a circuit design. An expander allocates cells to tiles, wherein some tiles have cells. The expander determines a high detailed routing cost tile class, wherein the high detailed routing cost tile class is a class of tiles that are high detailed routing cost tiles. The expander selects a cell within a tile of the high detailed routing cost tile class to form a selected cell and a selected tile. The expander places an expanded bounding box around the selected cell, wherein the bounding box extends to at least one tile adjacent the selected tile. The expander expands the selected cell within the bounding box to form a modified design, determines an aggregate routing cost among other steps, and affirms the modified design for further processing.

Abstract: A computer implemented method, data processing system, and computer program product for reworking a plurality of cells initially placed in a circuit design. An expander allocates cells to tiles. The expander determines a high detailed routing cost tile class, wherein the high detailed routing cost tile class is a class of tiles that has high detailed routing costs. The expander selects a cell within a tile of the high detailed routing cost tile class to form a selected cell in a selected tile. The expander applies multiple techniques to reposition these cells at new locations to improve the detailed routability. The expander can place an expanded bounding box around the selected cell, wherein the bounding box extends to at least one tile adjacent the selected tile, and repositions the selected cell within the bounding box to form a modified design to improve the detailed routability. The expander may also inflate and legalize those cells.

Abstract: Power, routability and electromigration have become crucial issues in modern 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 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: An automated method and apparatus for positioning gate array circuits in an integrated circuit design. An initial integrated circuit design includes logic cells and gate array fill circuits positioned thereon. The gate array fill circuits are positioned in available space between the adjacent logic cells so as to fill the available space with the maximum gate array fill circuits. A gate array logic element to be positioned in the integrated circuit design, such as may be required by an engineering change to the circuit design, is automatically positioned between adjacent logic cells so as to allow for full utilization of any space remaining between the adjacent logic cells by gate array fill circuits.

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: Scheduling of parallel processing for regionally-constrained object placement selects between different balancing schemes. For a small number of movebounds, computations are assigned by balancing the placeable objects. For a small number of objects per movebound, computations are assigned by balancing the movebounds. If there are large numbers of movebounds and objects per movebound, both objects and movebounds are balanced amongst the processors. For object balancing, movebounds are assigned to a processor until an amortized number of objects for the processor exceeds a first limit above an ideal number, or the next movebound would raise the amortized number of objects above a second, greater limit. For object and movebound balancing, movebounds are sorted into descending order, then assigned in the descending order to host processors in successive rounds while reversing the processor order after each round. The invention provides a schedule in polynomial-time while retaining high quality of results.

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: 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.