A method for reducing global routing congestion

Abstract

The present invention provides a method for reducing global wiring congestion, which relates to the field of circuit design technology, traversing the wiring units in the original global network to determine the network with overflow; locating the unit that needs to be moved according to the congested position of the network with overflow; swapping the position of the unit that needs to be moved with its adjacent unit of the same size and rewiring to form a current global network with an unchanged network structure; comparing the overflow value of the current global network with the overflow value of the original global network, if the overflow value of the current global network is less than the overflow value of the original global network, then retaining the current global network. This technical solution solves the technical problem of how to efficiently and coordinately reduce global wiring congestion in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to a method for reducing global wiring congestion. Background Art

[0002] Placement and routing are often viewed as two separate problems that are addressed in a divide-and-conquer manner to reduce design complexity. To address both challenges in a timely manner, traditional approaches break the entire process down into multiple sub-problems, including global placement, legalization, detailed placement, global routing, and detailed routing. While this decomposition approach helps address specific issues at each stage, it also has some shortcomings that lead to a lower quality solution. This is because the correlation and goals between these issues are not completely aligned, which also provides room for improvement in subsequent steps.

[0003] The current separation of layout and routing can help to better solve the current problems, but it also brings certain challenges. The existing local cell movement technology is to improve the line length and vias on the basis of no congestion after global routing. However, in complex and large circuits, most of them are congested, and the emergence of global routing congestion leads to more violations of design rules in subsequent steps and circuit timing disorder.

[0004] In view of such situations, the present invention proposes to optimize the layout by relocating the congested wiring units based on the wiring as a guide, so as to improve the quality of the wiring results. However, the current local unit movement method mainly aims to reduce the line length and through holes, and lacks the strategy of using the unit movement method to solve the global wiring congestion.

[0005] When optimizing local unit movement methods, it is necessary to consider global routing congestion and ensure that placement adjustments are not just to meet local routing indicators. By adopting a routing-oriented approach during the layout phase, congested areas can be relocated more effectively, thereby improving overall performance. Such local unit movement methods should comprehensively consider the impact of global routing to improve the quality of the overall solution. In this regard, the refinement and extension of the method can better balance the needs of local and global optimization to obtain a more superior circuit design. Summary of the invention

[0006] The purpose of the present invention is to provide a method for reducing global routing congestion to solve the technical problem of how to efficiently and coordinately reduce global routing congestion in the prior art. The preferred technical solutions among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0007] To achieve the above object, the present invention provides a method for reducing global routing congestion, comprising:

[0008] Traversing the wiring cells in the original global network to determine the network with overflow;

[0009] Positioning a unit that needs to be moved according to a congested location of the network with overflow;

[0010] The unit to be moved is exchanged with its adjacent units of the same size and rewired to form a current global network with an unchanged network structure;

[0011] The overflow value of the current global network is compared with the overflow value of the original global network. If the overflow value of the current global network is smaller than the overflow value of the original global network, the current global network is retained.

[0012] In some embodiments, locating the unit that needs to be moved according to the congested location of the network with overflow includes:

[0013] If the congestion is located between two pins of the network with overflow, one of the cells located on both sides of the congestion is determined as a cell that needs to be moved.

[0014] In some embodiments, determining one of the cells located on both sides of the congestion as a cell that needs to be moved includes:

[0015] The cell with a lower degree among the cells located on both sides of the congestion is determined as the cell that needs to be moved.

[0016] In some embodiments, the unit that needs to be moved according to the congested location of the network with overflow further includes:

[0017] If the congestion is located between the pin of the net with overflow and the Steiners point, the pins next to the congestion are relocated to form the current global net.

[0018] In some embodiments, it also includes:

[0019] The overflow value of the current global network is compared with the overflow value of the original global network. If the overflow value of the current global network is greater than the overflow value of the original global network, the global network is restored to the original global network.

[0020] In some embodiments, traversing the wiring units in the original global network to determine the network with overflow includes:

[0021] The wiring cells in the original global network are traversed, and the network with overflow is identified by calculating the capacity of each wiring cell.

[0022] The technical solution of the present invention may include the following beneficial effects:

[0023] The present invention provides a method for reducing global wiring congestion. The present technology can generate higher quality global wiring results. By reacting to wiring congestion through global wiring and then solving the congestion problem by moving local units, congestion can be directly alleviated, layout bottlenecks can be fully understood, and coordinated optimization of layout and wiring can be achieved, narrowing the gap between them and improving the efficiency and performance of circuit design. This design makes the entire circuit layout and wiring more efficient and coordinated. It can be seen that the present technical solution solves the technical problem of how to efficiently and coordinately reduce global wiring congestion in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is a flow chart of a method for reducing global routing congestion according to an embodiment of the present invention;

[0026] Figure 2a is a schematic diagram of a congested location in a wiring network according to an embodiment of the present invention;

[0027] Figure 2b It is a schematic diagram of structural processing based on a congestion position in a wiring network in an embodiment of the present invention;

[0028] Figure 3a is a schematic diagram of another congested location in a wiring network according to an embodiment of the present invention;

[0029] Figure 3b It is a schematic diagram of structural processing based on another congestion position in a wiring network in an embodiment of the present invention;

[0030] Figure 4a is a schematic diagram of a congested network wiring in an embodiment of the present invention;

[0031] Figure 4b It is a schematic diagram of local unit movement and rewiring based on congestion in an embodiment of the present invention.

[0032] In the figure: 1. Pin; 2. Steiner point; 3. Congestion; 4. Unit I that needs to be moved; 5. Unit II that needs to be moved. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0034] When optimizing local unit movement methods, it is necessary to consider global routing congestion and ensure that placement adjustments are not just to meet local routing indicators. By adopting a routing-oriented approach during the layout phase, congested areas can be relocated more effectively, thereby improving overall performance. Such local unit movement methods should comprehensively consider the impact of global routing to improve the quality of the overall solution. In this regard, the refinement and extension of the method can better balance the needs of local and global optimization to obtain a more superior circuit design.

[0035] like Figures 1 to 4b As shown:

[0036] The present invention provides a method for reducing global routing congestion, comprising:

[0037] S01 traverses the wiring units in the original global network to determine a network with overflow;

[0038] S02 locates a unit that needs to be moved according to a congested position of the network with overflow;

[0039] S03: swapping the position of the unit to be moved with its adjacent units of the same size and rewiring them to form a current global network with an unchanged network structure;

[0040] like Figure 4a , Figure 4b As shown, based on the existing placement and routing, the cell movement is combined. By relocating the cells and rerouting the network, a better placement and routing solution is achieved, while reducing overflow.

[0041] Faced with problems that cannot be adequately addressed by traditional routing strategies, local cell movement is introduced to make local improvements to the original layout. Identifying the specific cells that need to be relocated becomes a key aspect of this strategy. However, the importance lies not only in the identification process, but also in the careful selection of the best locations for these cells. Careful consideration of cell placement is essential to ensure effective congestion relief while maintaining the overall integrity and performance of the chip design. This nuanced approach to local cell movement during routing means a proactive response to the ever-changing challenges posed by the trend of ever-decreasing chip feature sizes. Our strategy involves moving cells of the same size that are very close to each other, such as cell I4 and cell II5 that need to be moved as shown in the figure. By doing so, when cells of the same size are moved relative to each other, the positions of the surrounding cells do not need to be adjusted; this approach ensures that the network structure of the surrounding cells remains unchanged, maintaining the relative stability of the network. In contrast, moving cells of different sizes can provide a larger solution space, but may result in the rerouting of the network of the moved cells, destroying the overflow stability of the original network. The purpose of selecting neighboring cells is to ensure that the total length of the network does not increase significantly, thereby maintaining network efficiency.

[0042] S04 compares the overflow value of the current global network with the overflow value of the original global network. If the overflow value of the current global network is smaller than the overflow value of the original global network, the current global network is retained.

[0043] Specifically, after the move is completed, the connection between the networks needs to be established and the overflow value of the network needs to be calculated. We compare the overflow value of the moved network with the overflow value of the original network to determine whether the network performance has improved. If the overflow value of the original network is greater than the overflow value of the moved network, the new position of the moved unit and the network routing information are retained. This indicates that the move operation is effective and has a positive impact on network performance.

[0044] When optimizing the local unit movement method, the global routing congestion is taken into account, and the placement adjustment is ensured not only to meet the local routing indicators. The impact of global routing is comprehensively considered when moving local units, which improves the quality of the overall solution.

[0045] like Figure 2a , Figure 2b As shown, in some embodiments, the unit that needs to be moved according to the congestion 3 position of the network with overflow includes:

[0046] If the congestion 3 is located between two pins 1 of the network with overflow, one of the cells located on both sides of the congestion is determined as a cell that needs to be moved.

[0047] In some embodiments, determining one of the cells located on both sides of the congestion 3 as a cell that needs to be moved includes:

[0048] Among the cells located on both sides of the congestion 3, the cells with lower degrees are determined as cells that need to be moved.

[0049] Specifically, by analyzing the network with overflow and analyzing the cells that cause the overflow. There are two main scenarios: one involves congestion between two pins 1, and the other involves congestion between pin 1 and Steiners Point 2. When congestion occurs between two pins 1 in the same network, it is advocated to give priority to cells with lower degrees. After relocating cells with lower degrees and subsequently rewiring, the number of connections required for the network is reduced, thereby reducing the potential risk of congestion. In contrast, the movement of cells with higher degrees may lead to more complex routing arrangements, thereby increasing the possibility of congestion.

[0050] like Figure 3a , Figure 3b As shown, in some embodiments, the unit that needs to be moved according to the congestion 3 position of the network with overflow further includes:

[0051] If the congestion 3 is located between the pin 1 of the network with overflow and the Steiners point 2, the pin 1 next to the congestion 3 is relocated to form the current global network.

[0052] Specifically, when resolving congestion between pin 1 and Steiners point 2, relocating the pins can change the routing, thereby reducing the possibility of overflow. Although moving pins may affect the structure of the connection network, considering that congestion mainly occurs between pins and Steiners points, clever adjustments to the pin locations where cells are located have the potential to optimize the connection path and reduce overflow.

[0053] In some embodiments, it also includes:

[0054] The overflow value of the current global network is compared with the overflow value of the original global network. If the overflow value of the current global network is greater than the overflow value of the original global network, the current global network is restored to the original global network.

[0055] If the overflow value of the moved network is greater than the overflow value of the original network, the move operation is undone and the initial position and wiring of the moved cells are restored, which ensures a cautious and effective approach to optimize the network structure.

[0056] In some embodiments, traversing the wiring units in the original global network to determine the network with overflow includes:

[0057] The wiring cells in the original global network are traversed, and the network with overflow is identified by calculating the capacity of each wiring cell.

[0058] Specifically, we adopted the most advanced 3D global router and added a local cell move stage to it. In the preprocessing stage, cell moves can be optionally performed after the maze routing is completed. The basic principle is to use the guidance information generated by the original global router to maximize the optimization of cell placement. By traversing each network and calculating the capacity of the global routing cell based on the generated guidance information, the core of this strategy is to use the guidance information to accurately identify overflowing networks by calculating the capacity of each global routing cell. Operating on the existing output results, taking advantage of its global routing and ensuring that the cell move process is based on the already high-quality placement. This preprocessing stage not only allows us to identify overflowing networks, but also allows us to adjust cell positions more purposefully. The careful treatment of this step helps to improve the performance of the algorithm and lays a solid foundation for subsequent optimizations throughout the process.

[0059] The technical solution of the present application aims to reduce congestion. The result after global routing reflects the congestion of the layout. The congested area uses unit movement to reduce the global routing congestion. Specifically, the present invention reduces the congestion of global routing by moving local units, narrows the gap between layout and routing, and is an effective method for collaborative optimization of layout and routing.

[0060] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0061] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for reducing global routing congestion, characterized in that, include: Traversing the wiring cells in the original global network to determine the network with overflow; Positioning a unit that needs to be moved according to a congested location of the network with overflow; The unit to be moved is exchanged with its adjacent units of the same size and rewired to form a current global network with an unchanged network structure; Comparing the overflow value of the current global network with the overflow value of the original global network, if the overflow value of the current global network is less than the overflow value of the original global network, retaining the current global network; Wherein, the unit that needs to be moved is located according to the congested position of the network with overflow, including: If the congestion is located between two pins of the network with overflow, one of the cells located on both sides of the congestion is determined as a cell that needs to be moved; wherein determining one of the cells located on both sides of the congestion as a cell that needs to be moved includes: Determine the cell with a lower degree among the cells located on both sides of the congestion as the cell that needs to be moved; as well as, If the congestion is located between the pin of the net with overflow and the Steiners point, the pins next to the congestion are relocated to form the current global net.

2. The method for reducing global routing congestion according to claim 1, characterized in that: Also includes: The overflow value of the current global network is compared with the overflow value of the original global network. If the overflow value of the current global network is greater than the overflow value of the original global network, the current global network is restored to the original global network.

3. The method for reducing global routing congestion according to claim 1 or 2, characterized in that: The traversing of the wiring units in the original global network to determine the network with overflow includes: The wiring cells in the original global network are traversed, and the network with overflow is identified by calculating the capacity of each wiring cell.

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