Xilinx, Inc.

Zhiyong Wang

Sabyasachi Das

Ruibing Lu

Aaron Ng

Niyati Shah

Aman Gayasen

Rajat Aggarwal

Kai Zhu

Sreesan Venkatakrishnan

Lin Chai

Disclosed approaches for pipelining signal paths in an integrated circuit (IC) device include receiving by a design tool a circuit design to be implemented in the integrated circuit device. The design tool identifies signals of the circuit design that require pipeline registers between drivers and loads of the signals, and relaxes an initial timing requirement to a relaxed timing requirement. The design tool determines respective numbers of pipeline registers to insert between each driver and load of each of the signals based on the relaxed timing requirement. The design tool inserts in the circuit design, respective sets of the respective numbers of pipeline registers between each driver and load of each of the signals. The design tool places the respective sets of the pipeline registers on the IC device using the initial timing requirement.

Insertion and placement of pipeline registers in signal paths of an integrated circuit

Methods and apparatus for implementing a circuit design are provided. A physical description is generated corresponding to a predefined physical layout of a programmable integrated circuit. The circuit design includes a memory block. A timing analysis is executed to determine a first timing profile of the physical description. The physical description is optimized (or at least altered), and a physical implementation is generated based on the optimized physical description. Optimizing the physical description includes: selectively moving from or into the memory block of the physical description a register in response to an attribute of the memory block; executing a timing analysis to determine a second timing profile of the physical description with the register moved from or into the memory block of the physical description; comparing the first and second timing profiles; and selectively accepting or reversing the moving based on the comparison of the first and second timing profiles.

Timing optimization of memory blocks in a programmable IC

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing physical synthesis with an overall placement process. One of the methods includes receiving an initial netlist of a circuit design for an IC. A global placement process is performed that assigns to some components in the initial netlist a respective initial location on the IC. One or more physical synthesis processes are performed to generate a modified netlist before assigning a final location to all components in the circuit design by an overall placement process. A subsequent placement process is performed to assign a final location on the IC to all components in the modified netlist.

Physical synthesis within placement

Physical synthesis for a circuit design can include determining, using a processor, a candidate net from a circuit design, wherein the candidate net spans a plurality of dies of a multi-die integrated circuit, and modifying, using the processor, the candidate net by performing physical synthesis resulting in a modified candidate net. The physical synthesis includes relocating a driver or a load of the candidate net or replicating the driver of the candidate net. An incremental routing can be performed on the modified candidate net using the processor. Further, the modified candidate net can be selectively committed using the processor based upon a timing analysis.

Physical synthesis for multi-die integrated circuit technology

Implementing a partial reconfiguration design flow can include determining an interface net connecting static circuitry and a first reconfigurable module of a circuit design, performing, using a processor, a logical optimization on first circuitry of the static circuitry that is entirely external to the first reconfigurable module and on second circuitry entirely within the reconfigurable module, and excluding the interface net from processing using the logical optimization.

Logical and physical optimizations for partial reconfiguration design flow

A method of circuit design may include synthesizing a circuit design using a processor and, for the synthesized circuit design, selectively reducing, using the processor, fanout of nets having a number of loads exceeding a first threshold number of loads and having a selected netlist connectivity. The method may include placing the circuit design using a processor and, for the placed circuit design, selectively reducing, using the processor, fanout of nets according to at least one of a number of loads or criticality.

Fanout optimization to facilitate timing improvement in circuit designs

Aspects of processing a circuit design include synthesizing the circuit design and placing elements of the synthesized circuit design. After placing and before routing, respective delay values and slacks are determined. A first path having a most negative slack is determined and a first group of candidate paths is selected. The first group of candidate paths is a subset of critical paths of the circuit design, and the first group of candidate paths have delay values within a threshold range of delay values from the delay value of the first path. The first group of candidate paths are modified to reduce the respective delay values and a second group of candidate paths is selected. The second group of candidate paths have circuit structures that match selected circuit structures and are modified to reduce the respective delay values. A critical path having a most negative slack is iteratively selected and modified to reduce the respective delay value.

Post-placement and pre-routing processing of critical paths in a circuit design

Post-routing processing of a circuit design may include determining, using a processor, a baseline delay for a path of a routed circuit design, comparing, using the processor, the baseline delay of the path with a timing constraint of the path, and selectively applying, according to the comparing, a structural netlist optimization to the path resulting in an optimized path using a processor.

Post-routing structural netlist optimization for circuit designs

A processor-implemented method is provided for placing and routing a circuit design. A first netlist is generated for the circuit design. Placement is performed for the first netlist on a target programmable integrated circuit (IC) to produce a first placed design. A set of optimizations are performed on the first placed design. The set of optimizations are recorded in an optimization history file. One or more optimizations specified in the optimization history file are performed on the first netlist to produce a second netlist that is different than the first netlist. Placement is performed for the second netlist on the target programmable IC to produce a second placed design that is different than the first placed design. Nets of the second placed design are routed to produce a placed and routed circuit design.

Interactive multi-step physical synthesis

In an example, a method of implementing a circuit design for an integrated circuit (IC) includes: placing and routing a logical description of the circuit design to generate a physical description having a plurality of paths, and executing a timing analysis to determine a timing profile of the physical description. The method further includes optimizing the physical description by performing a plurality of iterations of: comparing the timing profile with a timing constraint to select a candidate set of paths having negative slack from the plurality of paths in the physical description; and modifying the physical description based on at least one optimization of a selected path from the candidate set of paths having a most negative slack. The method further includes generating a physical implementation of the circuit design for the IC based on the physical description.

Opportunistic candidate path selection during physical optimization of a circuit design for an IC

In an approach for processing a circuit design by a programmed processor, a placed circuit design that has been placed on programmable resources of a programmable integrated circuit (IC) is input. A critical path is determined from a first sequential element to a second sequential element assigned to the placed circuit design. A first clock buffer that provides a clock signal to the first and second sequential elements is determined, and an unused clock buffer is selected based on proximity to the first sequential element. The circuit design is modified to include the unused clock buffer as a second clock buffer coupled to receive a clock signal in parallel with the first clock buffer and to provide a clock signal to the first sequential element.

Selective addition of clock buffers to a circuit design

Physical optimization for timing closure for an integrated circuit includes processing a circuit design at least partially through a design flow to a late stage of the design flow. Using a processor, a baseline delay is calculated for each of a plurality of paths of the circuit design. A slack for each of the plurality of paths is determined. Physical optimization further includes selecting a path of the circuit design that meets a selection criterion according, at least in part, to the slack of the path, applying, using the processor, a physical optimization to the selected path resulting in an optimized path, and calculating a delay of the optimized path. The optimized path is incorporated into the circuit design only responsive to determining that the delay of the optimized path is less than the baseline delay of the selected path.

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Cupertino, CA, United States of America

Zhiyong Wang