Patent Application
20050050503
Users of E-CAD (electronic computer-aided design) tools may encounter unexpected results when changes are made to a VLSI data model while the model is being analyzed. Typically, E-CAD tools do not check for data consistency between the subsequent execution of different sub-tools during a given analysis of a data model. The assumption is generally made that VLSI design engineers responsible for the data model will not make changes to the model while an analysis is being run. Frequently, however, a data model is, in fact, modified during an analysis run, resulting in unexpected behavior and anomalous output from an analysis tool. Valuable design engineer time and resources may thus be spent in attempting to determine the cause of the unexpected and/or anomalous results. What is needed is a method of ensuring that an E-CAD tool will not produce unreliable results when a data model under analysis is modified during the analysis. Alternatively, the source data can be locked down while analyzing it, to guarantee that changes cannot be made during analysis. This alternative is, of course, disadvantageous because it precludes the designers from making progress on the design of the chip while an analysis is underway.
A disclosed embodiment includes a system for establishing consistency, with respect to a data model, between sub-modules within an E-CAD tool. A consistency database, including at least one consistency indicator for each block of interest in the data model, is initially created. One or more of the sub-modules is then executed to perform an analysis of a current version of the data model. At least one data field value, corresponding to the consistency indicator, is compared for each block of interest, in source files in the current version of the data model being analyzed, against a corresponding consistency indicator in the consistency database. A warning is issued, indicating a possible discrepancy between data in the current version of the data model and corresponding data in a previous version of the data model, if a difference is detected between at least one data field value in the current version of the data model being analyzed and the corresponding consistency indicator.
A more complete understanding of the present system and method may be obtained by reference to the drawings, in which:
Upon initialization, E-CAD sub-tool 107(*) is loaded into computer memory 104. Processor 102 executes comparison module 111 as part of the set of E-CAD instructions being executed by sub-tool 107(*). At least part of the circuit design 109 under analysis is also loaded in computer memory 104. Design 109 includes a data model 105, which comprises various components that are modified from time to time during the analysis of the design. In an exemplary embodiment, system 100 includes a user interface module 112 that is used for indicating a difference between consistency data (described below) in data model 105 and corresponding consistency data in database 113 determined by a previous analysis.
In an exemplary embodiment, comparison module 111 is configured for reading and comparing consistency indicators 103, including timestamp and other optional consistency data in data model 105, against data stored in a consistency database 113 containing similar-type information determined by a previous analysis of the data model. Comparison module 111 queries consistency database 113 to ensure that the design data in data model 105 is unchanged since that particular data model was last updated in consistency database 113. If there are any discrepancies in the consistency information between data model 105 and consistency database 113, user interface module 112 issues a warning to a user to indicate the possible inaccuracy of results due to design data inconsistency.
In step 205, comparison module 111 stores, in consistency database 113, one or more of the consistency indicators 103 comprising timestamp values in the source file for each block in the baseline data model 105, as determined during a previous analysis of the block. A new consistency database 113 is created for each run of each analysis tool 107, which may have multiple modules (sub-tools) 107(*) that all access the same consistency database 113 and source files. The consistency indicators 103 that are stored in step 205 include timestamp information which indicates the time of creation or last modification of a file containing data for a particular block in data model 105. More specifically, this timestamp information includes the processor machine time, and optionally, the date and/or the 24 hour clock time.
At step 210, additional consistency indicators 103, such as the file size of source files in a data model 105, may also be stored in consistency database 113 for each block of interest in the data model.
An example of the types of data that may be stored in consistency database 113 is indicated below in Table 1.
As shown in the Sample Consistency Database of Table 1, each file under the heading ‘BdlFile’ is the name of the source file that contains the various types of data (e.g., wire capacitance [‘wire_cap’] data) indicated by the table entries under the heading ‘DataType’. E-CAD tool 107 or sub-tools 107(*) also use the ‘DataType’ and, in addition, the ‘RepType’ (data source, e.g., artwork) information in consistency database 113 to determine the files to be used for analysis of data model 105. The entries in Table 1 indicated as ‘BdlMachTime’, ‘BdlDate’, and ‘BdlTime’ are consistency indicators 103 that represent the respective processor machine time, the date, and the 24 hour clock time when the associated ‘BdlFile’ file was either created or last modified.
In step 215, at least one sub-tool 107(*) of E-CAD tool 107 is run (executed by processor 102) to analyze a current version of data model 105 by performing the steps in section 220 for each block of interest in the data model. In step 225, a presently running sub-tool 107(*) causes an integrated (or associated) comparison module 111 to be executed. Comparison module 111 then compares data field values comprising timestamp values for each block of interest, in source files in the data model 105 presently being analyzed, against timestamp consistency indicators 103 in consistency database 113. More specifically, using the nomenclature in the Sample Consistency Database of Table 1, data fields representing BdlMachTime, and optionally, BdlDate, and BdlTime, in source BdlFile in data model 105, are checked against the corresponding consistency indicators 103 in consistency database 113. In an exemplary embodiment, these ‘corresponding consistency indicators’ 103 are the corresponding identical fields in the data model 105 presently being analyzed. A plurality of sub-tools 107(*) may be simultaneously operational, in which case, the present system 100 provides a mechanism of detecting modifications made to data model 105 by a sub-tool 107(*) other than the one which may be currently executing comparison module 111.
In step 230, which is optional in one embodiment, additional consistency data, such as the file size of source files in a data model 105, may also be compared to corresponding consistency indicators 103 in consistency database 113.
In step 235, comparison module 111 further processes each block in response to the comparison of the block data made in step 225, and optionally, in response to the comparison made in step 230, if additional consistency data was stored in consistency database 113 in step 210. If a timestamp or other inconsistency between the current data model 105 and consistency database 113 is found with respect to one or more consistency indicators 103, user interface module 112 issues a warning indicating a possible data discrepancy between the current data model 105 and a previous version of the data model in step 240. For example, the warning produced by interface module 112 may alert a user that a particular block in data model 105 should be recalculated or reanalyzed by E-CAD tool 107 or sub-tool 107(*).
Instructions that perform the operation discussed with respect to
Certain changes may be made in the above methods and systems without departing from the scope of the present system. It is to be noted that all matter contained in the above description or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense. For example, the items shown in
