JP2818246B2 - Automatic wiring method for integrated circuits - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to automatic wiring of an integrated circuit in which wiring processing is performed using parameter values automatically adjusted while performing wiring processing. About the method.

(Prior Art) In recent years, with the rapid development of semiconductor technology, integrated circuits have become larger and more multifunctional. This gives 1
A huge number of elements will be integrated on a chip.

As described above, when the scale of an integrated circuit is increased, development by hand is limited. Therefore, a CAD (Computer Ai) provided with various programs for automatically performing design and the like as tools.
ded Design) is frequently used.

As one of the CAD tools for developing integrated circuits, for example, in an automatic wiring program for automatically connecting integrated circuits, in a program development stage, a state change of an object to which the program is applied is predicted and changed. Since it is impossible to deal with it, a parameter is given as an element for determining a state change. The value of this parameter is not fixed and is adjusted based on the collected data by conducting experiments later to collect necessary data.

In an automatic wiring program including such parameters, even if the same program is used, a much better wiring result may be obtained only by changing the value of the parameter. For this reason, in adjusting the parameters, a number of experiments had to be repeated, which required a great deal of labor and time, and was extremely difficult. In addition, since the parameter value is usually adjusted so as to conform to the average model, the parameter value needs to be readjusted due to a complicated model or a change in conditions.

On the other hand, if the adjustment of the parameter values is insufficient, a satisfactory result cannot be obtained when the program is operated, and the program does not function effectively.

(Problems to be Solved by the Invention) As described above, in the conventional automatic wiring program used for the development of an integrated circuit, adjustment of parameter values set in the program requires extremely troublesome work. In addition to work, it was difficult to optimize parameter values.

In addition, while the parameter values are adjusted and then readjusted, the program is operated in a fixed state in which the parameter values are not optimized, so that good wiring results cannot be stably obtained. Was.

Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide an integrated circuit capable of automatically and optimally adjusting parameter values and obtaining good wiring results. An object of the present invention is to provide an automatic wiring method.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, when the wiring process of an integrated circuit is controlled by a parameter and automatically wired, the parameter is set within a predetermined range. Has a continuous parameter value that changes continuously within, performs a wiring determination process according to a plurality of discrete parameter values that are discretely extracted among the parameter values, and determines a wiring determination result in the executed wiring determination process. Evaluate according to the evaluation criteria, determine the evaluation result of the continuous parameter value according to the obtained evaluation result, and cumulatively update the evaluation result of the continuous parameter value to the evaluation result corresponding to the already determined continuous parameter value. In the cumulatively updated evaluation result, the parameter value of the next wiring determination process is set with a probability that a parameter value satisfying a predetermined criterion is more likely to be selected. Configured to constant.

(Operation) In the above configuration, according to the present invention, a parameter value with a higher evaluation result is selected with a higher probability from among parameter values updated according to an evaluation result of the wiring process obtained each time the wiring process is executed. The next wiring process is performed by using the parameter values selected under various conditions.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a main configuration of an apparatus for automatically wiring an integrated circuit by an automatic wiring method for an integrated circuit according to an embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of the apparatus shown in FIG. It is an operation flowchart.

In the configuration of the embodiment shown in FIG. 1, the value of the parameter is updated in accordance with the wiring result each time wiring is completed in a preset wiring area.

1, the apparatus includes a wiring processing unit 1, a wiring storage unit 2, an output unit 3, an evaluation unit 4, an evaluation value determination unit 5, an evaluation value storage unit 6, and a parameter value determination unit 7.

The wiring processing unit 1 inputs wiring information and parameter values necessary for performing the wiring processing, and executes the wiring processing according to the information.

In the automatic wiring processing shown in this embodiment, as shown in FIG. 3, one chip is divided into a large number of wiring areas 21, and each wiring area 21 is sequentially wired to complete the wiring of the entire chip. ing. The procedure of the wiring processing shown in this embodiment is to determine a specific wiring path in each wiring area 21. Among the schematic wiring grids 22 that divide the wiring area 21 appropriately, a schematic wiring path indicating which grid the wiring passes through is determined by another wiring program.

The wiring processing unit 1 executes the above-described wiring processing in each wiring area as a kind of “switch box router” that connects between terminals arranged on the outer periphery of the rectangular area. That is, the wiring processing unit 1 performs wiring processing by sequentially connecting the terminals inside the wiring area by the line segment search method.

The sequential wiring method such as the line segment search method has a drawback that wiring laid so far may interfere with wiring to be laid. In particular, when another wiring is laid in the vicinity of the terminal from which the wiring is not drawn, the wiring path of the terminal from which the wiring is not drawn is restricted, which makes wiring difficult.

In order to solve such a problem, in a router for wiring processing executed by the wiring processing unit 1, as shown in FIG.
Regions referred to as "power ranges" 33 and 34 are virtually drawn from 2, and a power range drawn from terminals other than the terminal to be wired is set as a wiring prohibited region. By setting such a range of influence, the approach of other wiring to the vicinity of a terminal where wiring is not performed is suppressed, thereby facilitating wiring drawing in the future.

In such a power range, in this embodiment, the length of the power range is used as a parameter, and the value of this parameter is given from the parameter value determination unit 7 described later to the wiring processing unit 1. Here, the value of the parameter is given, for example, as a ratio (%) to the length of one side of the wiring region.

Therefore, the wiring processing unit 1 provides, for one wiring area, a netlist serving as wiring information, a terminal shape and position,
With the shape and position of the wiring prohibited area 35 shown in FIG. 4 and the schematic wiring result as input, changing the parameter value given as the length of the power range eliminates the short-circuited part or eliminates the wiring processing set in advance. Repeat the wiring process until the number of trials is reached.

The wiring storage unit 2 stores and stores the result of the wiring executed by the wiring processing unit 1. The stored wiring result is provided to the output unit 3.

The output unit 3 integrates and outputs the wiring results provided from the wiring storage unit 2. Further, the output unit 3 outputs the stored contents stored in an evaluation value storage unit 6 described later.

The evaluation unit 4 calculates the wiring result executed by the wiring processing unit 1,
The “number of short-circuited parts”, which is a criterion for determining the quality of the wiring result, is evaluated as an evaluation item. The evaluation unit 4 evaluates a wiring result for each wiring process executed for a given parameter value. The evaluation result is provided to the evaluation value determination unit 5.

The evaluation value determination unit 5 gives a score (evaluation value) to the tried parameter value according to the evaluation result given from the evaluation unit 4. For example, the number of short points is directly used as a score for the parameter value. Therefore, in such a way of giving a score, a wiring process using a parameter value with a small score obtains a better wiring result.

Also, the number of trials of the wiring process for one wiring area,
That is, since the number of parameter values to be tried is limited, it is insufficient to evaluate only the parameter values actually tried and to give a score.
Therefore, the parameter value is from 0 to 10
Focusing on the fact that the continuous amount changes in the range of 0%, the evaluation value determination unit 5 calculates the score for the parameter value that has not been actually tried from the score of the tried parameter value by, for example, a linear interpolation method. I am trying to do it.

In such an interpolation process, when interpolating a parameter value larger than the maximum parameter value and a parameter value smaller than the minimum parameter value, the same score as the closest parameter value among the tried parameter values is used. give. For example, in one wiring area, 30
If the score (short part) for the parameter value of% is “3” and the score for the parameter value of 60% is “1”, the score for the parameter value of 30% or less is “3” and the parameter of 60% or more The score for the value is "1" and the scores for the parameter values between 30% and 60% are assigned by linear interpolation as shown in FIG.

Further, the evaluation value determination unit 5 sequentially accumulates the score obtained each time the wiring process of one wiring region is completed every time the wiring process of one wiring region is completed for each of the same parameters. Is calculated. The calculated cumulative score is
It is provided to the evaluation value storage unit 6 together with the corresponding parameter value.

The evaluation value storage unit 6 stores and stores the cumulative score and the parameter value provided from the evaluation value determination unit 5. The stored contents are provided to the output unit 3 as necessary,
The parameter value is given to the parameter value determination unit 7.

The parameter value determination unit 7 determines a parameter value in the next wiring process using the accumulated score given from the evaluation value storage unit 6. The parameter value determination unit 7 probabilistically selects and determines parameter values with such a probability that a parameter value having a better cumulative score is more likely to be selected.

Therefore, the smaller the cumulative score is, the better the wiring result is. Therefore, the probability that the parameter value is selected is proportional to the reciprocal of the cumulative score of the parameter value, and the parameter value is a continuous amount. Given as a probability distribution. The parameter values determined in this way are provided to the wiring processing unit 1.

Next, the operation of the above configuration will be described with reference to the flowchart shown in FIG.

First, an initial value (for example, “1”) is set in the wiring processing unit 1 for each parameter value to be tried (step 100). Subsequently, after inputting the wiring information of the wiring area to be wired to the wiring processing unit 1 (step 110), the number of trials is set to "1" (step 120), and the number of trials is set in advance to the maximum number of trials. Compared (step 13
0).

If the number of trials does not exceed the maximum number of trials, the parameter value for the next wiring process is selected by the parameter value determination unit 7 with a probability proportional to the reciprocal of the accumulated score obtained up to that time (step 140). Here, in the first parameter value selection, since there is no accumulated score up to that point, each parameter value is selected with equal probability.

The selected parameter value is provided from the parameter value determination unit 7 to the wiring processing unit 1, and wiring processing of the wiring area is performed by the wiring processing unit 1 based on the input wiring information and the selected parameter value ( Step 150). When the wiring processing is completed, the wiring result is stored and stored in the wiring storage unit 2 (step 160).

Further, the wiring result is provided to the evaluation unit 5, a short-circuited portion is searched from the wiring result, and the number thereof is provided to the evaluation value determining unit 5 together with the corresponding parameter value. The score is given and stored (step 170).

In the evaluation of the wiring result, if there is a short-circuited portion, the number of trials is incremented (steps 180 and 19).
0), as shown in steps 130 to 170 described above, another parameter value is selected in the same wiring area, and the wiring processing is performed again.

As described above, in the wiring processing executed by changing the parameter value in the same wiring area, if the number of trials reaches the maximum number of trials or if there are no short-circuited parts in the wiring result, the trial is performed until that time. The score for the parameter value that has not been tried is calculated by interpolation from the score obtained for the set parameter value (steps 130, 180, 200). The calculated score is added to the accumulated score corresponding to the same parameter value obtained so far, accumulated, and stored in the evaluation value storage unit 6 (step 210).

In this way, when the wiring processing in one wiring area is completed and the wiring processing in the next wiring area is performed, the parameter value corresponding to the accumulated score stored in the evaluation value storage unit 6 determines the parameter value. The parameter value is provided to the unit 7 and the operation of the above-described steps 110 to 210 is executed.

When the wiring processing in all the wiring regions of one chip is completed in this way (step 220), the obtained wiring results are integrated and output from the output unit 3 (step 23).
0).

The result of the example in which the automatic wiring of the integrated circuit was actually performed by using the automatic wiring method described above is shown below.

The chip to which the above-described automatic wiring method was applied has 5700 nets, and was divided into 546 wiring areas and subjected to wiring processing.

First, the wiring process is performed by manually changing the parameter value from 0 to 100% in increments of 10% only in four wiring areas 21 (indicated by four types of line segments) randomly extracted from the 546 wiring areas. When the number of short-circuits at the time of performing was evaluated, an evaluation result as shown in FIG. 6 was obtained. As is clear from FIG. 6, the best result is obtained when the parameter value is 30%.

Next, the case where the parameter value is “0”, that is, there is no power range, the case where the parameter value is fixed to the 30% value obtained from the evaluation result described above, and the case where the parameter value is The wiring process was performed by three kinds of parameter value setting methods in the case of automatically adjusting the parameter values shown in the embodiment. In these three types of wiring processing, wiring results as shown in FIG. 7 were obtained.

In FIG. 7, when there is no power range, there are 324 short-circuited points, 79 short-circuited points when the parameter value is fixed at 30%, and 34 short-circuited points when the parameter value is automatically adjusted. is there. For this reason, better wiring can be achieved by setting the power range. Furthermore, the number of short-circuit points is reduced to less than half in the case of automatically adjusting the parameter value, compared with the case where the length of the range of power is fixed and the wiring of the entire wiring area is performed. Can be obtained. If the wiring processing time is the time during which the CPU is operated, the method of automatically adjusting the parameter values requires trial and error wiring processing in some wiring areas, so that it is more effective than when the parameter values are fixed. The wiring processing time is about 60% longer.

The fact that a better result is obtained when the parameter value is automatically adjusted than when it is fixed is that good parameter values are learned by learning in the process of sequentially wiring each wiring region. There is nothing other than that. The effect of such learning is as shown in FIG.
From FIG. 8, it can be concluded from FIG. 8 that the value increases as the number of wiring regions for which the wiring processing has been completed increases, the parameter value converges to the optimum value, and the optimum value of the parameter is about 35%.

In FIG. 8, the value of the accumulated score after wiring all areas indicates the expected value of the number of short-circuited points when wiring all wiring areas with the parameter value corresponding to the score fixed. However, in FIG. 7, the number of short-circuited points at a parameter value of 0% is 79 at 324,30%, whereas the predicted value in FIG. 8 is 132,30 at 0%.
% Is 100.2.

The difference between the actual value and the expected value is attributable to the fact that all the expected values are averaged by the linear interpolation.

As described above, in this embodiment, the good parameter values are acquired each time the wiring processing of the wiring area is completed. Is selected with a high probability, and a good wiring result with few short-circuit points can be obtained.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be considered.

For example, as the evaluation items, the wiring length, the number of vias, the processing time, and the like may be added according to the required contents.

In addition, it can be said that the result of wiring is far better than the case where there is no short-circuited portion, and the case where the number of short-circuited portions is “0”. In the case of "", there may be a difference in how to give the score.

Further, the score may be given in consideration of the characteristics of the wiring area. The wiring region of an integrated circuit using a gate array or a standard cell has a substantially uniform wiring pattern, whereas the storage circuit has a different wiring pattern between its peripheral region and the memory region. For the wiring, the feature of the wiring area may be recognized, and the parameter value may be changed according to the area.

Furthermore, the present invention can of course be applied to a case where the values of a plurality of parameters are adjusted. In such a case, scores may be assigned according to the presence or absence of mutual interference in the parameters.

[Effect of the Invention] As described above, according to the present invention, the parameter value is automatically updated according to the evaluation result obtained by evaluating the wiring result obtained for each wiring process. The value can be adjusted to converge.

As a result, good wiring results can be obtained by performing wiring processing using such parameter values.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the configuration of an apparatus for performing wiring processing by an automatic wiring method for an integrated circuit according to an embodiment of the present invention, and FIG. 2 is a diagram showing the operation of the apparatus shown in FIG. FIG. 3 is an explanatory diagram showing the concept of the wiring area, FIG. 4 is an explanatory diagram showing the concept of the range of influence which becomes the parameter value, FIG. 5 is a diagram showing how to give a score in the parameter value, FIG. FIG. 8 to FIG. 8 are diagrams showing wiring results in wiring processing performed using parameters. 1 ... wiring processing unit, 2 ... wiring storage unit, 3 ... output unit, 4 ... evaluation unit, 5 ... evaluation value determination unit, 6 ... evaluation value storage unit, 7 ... parameter value determination unit.

Claims (2)

(57) [Claims] When a wiring process of an integrated circuit is controlled by a parameter and automatically wired, the parameter has a continuous parameter value that continuously changes within a predetermined range, and discrete parameters are included in the parameter value. A wiring determination process is performed in accordance with a plurality of discrete parameter values that are extracted in a specific manner, a wiring determination result in the executed wiring determination process is evaluated according to an evaluation criterion, and the continuous parameter value is determined in accordance with the obtained evaluation result. The evaluation result is obtained, the evaluation result of the continuous parameter value is cumulatively updated to the evaluation result corresponding to the already obtained continuous parameter value, and a parameter value that satisfies a predetermined criterion is selected from the cumulatively updated evaluation results. An automatic wiring method for an integrated circuit, wherein a parameter value of a next wiring determination process is determined with a probability that the wiring is easily performed. 2. The method according to claim 1, wherein the evaluation result of the continuous parameter value is obtained by interpolating the evaluation result obtained from the parameter value.