JP2655612B2 - External reference update method - Google Patents

Description

The present invention relates to a method of updating an external reference in an electronic computer system, and more particularly, to dynamically linking an object module on an external storage device to a running load module. The present invention relates to an external reference updating method in which an external symbol definition is always kept up to date.

[Conventional technology]

Conventionally, in an external link, information for relinking is not stored for an external symbol that has been linked once and the reference has been resolved. Therefore, when the dynamic link is performed a plurality of times, if an external symbol having the same name is input with respect to the already linked external symbol definition, the link request is simply ignored or input by the user. It was usually treated as an error.

[Problems to be solved by the invention]

In the conventional method described above, reference resolution for an external symbol having the same name is performed only once,
It has the following disadvantages. That is, a language processing system using an interpreter is one of the functions of dynamically linking an object module described and compiled in another compiler language to itself according to a user's instruction at the time of execution, and linking the object module to its own module. When an external symbol having the same name as the external symbol declared in the object module already exists in the main storage area, the dynamic link is not performed in the conventional method. This is a disadvantage in that the system must be restarted so that an external symbol having the same name does not exist in the main storage area, and dynamic linking must be performed again.

Generally, in a language processing system using an interpreter, a processing unit such as a function or a predicate can be defined at any time when the interpreter is executed. Further, it can be redefined at any time thereafter. References to those functions or predicates are always made to the latest one. This is because the reference method is an indirect reference through a name table or the like. It is an advantage of the interpreter system that the function or the like is always referred to the latest one. However, in the above-mentioned conventional reference resolution method for external symbols, the external symbol cannot always be kept up to date with reference to the external symbol, and the above advantage cannot be effectively utilized.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an external reference updating method that can automatically keep an external symbol definition always up-to-date without restarting the system. It is in.

[Means for solving the problem]

According to the present invention, in order to achieve the above object, a load module loaded into a main storage area and being executed dynamically links an object module existing in an external storage device to itself, and the object module is connected to one of the own modules. An external symbol management table for storing external symbols existing in a main storage area, and a reference location for each undefined external symbol corresponding to the undefined external symbol. Using an unresolved reference chain linked to a list format, in the computer system performing the dynamic link, an external symbol reference corresponding to a defined external symbol and recording a reference location to the defined external symbol It has a table and, when dynamically linking an object module, an external module defined in the object module. If an external symbol having the same name as the symbol has already been defined in the main storage area, the external symbol reference table is used to store the address of the new symbol in the reference location to the already defined external symbol. Is to be reset.

[Action]

In the external reference updating method of the present invention, an external symbol reference table provided corresponding to each defined external symbol is:
All the reference locations to the corresponding defined external symbol are recorded, and when the object module is dynamically linked, an external symbol having the same name as the external symbol defined in the object module is already defined in the main storage area. If this is the case, the external symbol definition is always kept up to date by resetting the address of the new external symbol to all the references to the already defined external symbol using the corresponding symbol reference table. .

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating the configuration and operation of an embodiment of an external reference updating method according to the present invention. The upper part of FIG. 1 shows the status of the main storage area 1 at a certain time before redefinition of external symbols. The lower part of the figure shows the state of the main storage area 1 at a certain point after redefining the external symbols. In this embodiment, a load module that is loaded into the main storage area and is being executed dynamically links an object module present in the external storage device to itself, and the object module can be executed as one module of the object module. The present invention is applied to an electronic computer system.

In the situation shown in the upper part of FIG. 1, the load module 2 has been loaded into the main storage area 1, and the object module 3-1 and another object module 3-2 called therefrom are also loaded into the main storage area 1. Have been. Here, an external symbol 4-1 having a name A is defined in the object module 3-2, and locations 8-1 and 8-2 referring to the external symbol having the name A are defined in the object module 3-1. Included, and their reference relationships have been resolved. That is, the addresses indicating the external symbols 4-1 are stored in the reference locations 8-1, 8-2. Reference numeral 5 in the figure is an external symbol reference table created as described later when resolving the reference to the external symbol 4-1. 8-1, 8-2 to refer to
Is recorded. In such a situation, the first
As shown in the lower part of the figure, when the object module including the external symbol 4-2 is loaded for dynamic link, the operating system that controls the dynamic link control etc. has the external symbol 4-2 already stored in the main memory. It is checked whether or not the external symbol 4-1 defined in the area 1 has the same name A, that is, whether or not the external symbol is to be redefined. If the external symbol 4-1 has the same name A, the lower part of FIG. As shown in FIG. 7, referring to the external symbol reference table 5 corresponding to the external symbol having the name A, all of the locations 8-1 and 8-2 that referred to the external symbol 4-1 are replaced with the external symbol 4-2. Update to reference. That is, an address indicating the external symbol 4-2 is set in the locations 8-1 and 8-2. Thus, the definition of the external symbol having the name A can be kept up to date.

Next, the process of creating the external symbol reference table 5 shown in FIG. 1 and the process of redefining the external symbols using the same will be described in more detail.

(1) Processing for Creating External Symbol Reference Table 5 A situation where the object module 3-1 in FIG. 1 has been loaded into the main storage area 1 but reference has not yet been resolved, that is, the object module 3-2 has not been loaded. In a situation in which the external symbol 4-1 is not defined in the main storage area 1, as shown in the upper part of FIG. 2, a reference location 8-1 for the external symbol having the name A in the object module 3-1. , 8-2 indicating an unresolved reference chain 6 in which entries 6-1 and 6-2 are connected in a list format. In such a situation, when the object module 3-2 including the definition of the external symbol 4-1 is loaded into the main storage area 1, the operating system, when following the unresolved reference chain 6 in the reference resolution processing, Reference locations 8-1,8- indicated by the respective entries 6-1 and 6-2 constituting the chain 6
The addresses of the entries 5-1 and 5-2 of the area secured for the external symbol reference table 5 as shown in the lower part of FIG.
To record. Thus, when resolving the reference to the external symbol 4-1, the external symbol reference table 5 corresponding to the external symbol 4-1 is created.

If the number of references to the external symbol 4-1 increases, the external symbol reference table 5 is re-created accordingly. That is, in the situation shown in the upper part of FIG. 3 showing the same contents as the lower part of FIG. 2, the object module 3 further includes a location 8-3 referring to the external symbol 4-1 as shown in the lower part of FIG. When the object module 3-4 is loaded into the main storage area 1, each entry 5-1 and 5-2 of the external symbol reference table 5 (the state shown at the top of FIG. 3) immediately before the object module 3-4 is loaded. Reference location 8
An area large enough to store a new entry 5-3 for -3 is secured, the external symbol reference table 5 is copied there, and a new entry 5-3 is added.
As shown in the lower part of the figure, an external symbol reference table 5 'in which reference locations of all external symbols having the name A are recorded is created.

(2) External symbol redefinition processing Although not shown so far, each external symbol is
It is managed by the corresponding external symbol management table. As shown in FIG. 5, the external symbol management table has an entry 7-1 storing the name of the external symbol (external symbol name) assigned to the table itself, and an entry storing the entry / data head address of the external symbol. 7-2
And an entry 7-3 for storing the address of the external symbol reference table corresponding to the external symbol. Therefore, in the situation shown in the upper part of FIG. 1, there is an external symbol management table 7 corresponding to the external symbol 4-1 as shown in the upper part of FIG. And holds the address. When the object module 3-3 including the external symbol 4-1 having the same name A as the external symbol 4-1 is loaded as shown in the lower part of FIG. 1 and the lower part of FIG. The corresponding external symbol management table 7 is checked, and as a result, if the external symbol reference table exists, that is, if the content of the corresponding entry is not 0, the reference location indicated by the address recorded in the existing external symbol reference table 5 Write the address of the external symbol 4-2 for 8-1 and 8-2. In addition,
At this time, the entry / data head address in the external symbol management table 7 is updated.

〔The invention's effect〕

As described above, in the external reference updating method of the present invention, when an external symbol defined in a dynamically linked object module is redefined, that is, the same name as the external symbol defined in the object module is used. If another object module that defines an external symbol that has a target becomes the target of dynamic linking, all of the locations that previously referred to the external symbol should be automatically updated to reference the new external symbol Becomes possible. For this reason, when an interpreted language processing system dynamically links object modules output by other language compilers, the definition contents at the time when external symbols are dynamically linked without restarting the system. This has the effect that it can always be updated and can be referenced thereafter. Further, since the reference is directly changed, there is an effect that the processing speed of the object module is not affected at all.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration and operation of an embodiment of an external reference updating method according to the present invention, FIG. 2 is a diagram illustrating a process of newly creating an external symbol reference table, and FIG. FIG. 4 is an explanatory diagram of a process of updating a reference to an external symbol using an external symbol reference table, and FIG. 5 is a diagram showing a basic configuration of an external symbol management table. In the figure, 1... Main storage area 2... Load modules 3-1 to 3-4... Object modules 4-1 to 4-2... External symbols of the same name 5... External symbol reference table 6. Resolution reference chain 7 External symbol management table 8-1 to 8-3 Reference location of external symbol

Claims (1)

(57) [Claims] An electronic computer in which a load module being loaded into a main storage area and being executed dynamically links an object module present in an external storage device to itself, so that the object module can be executed as one of its own modules. An external symbol management table for recording external symbols existing in a main storage area, and an unresolved list corresponding to each undefined external symbol and linking a reference position to the undefined external symbol to a list. A computer system performing the dynamic link using a reference chain, the computer system having an external symbol reference table corresponding to the defined external symbol and recording a reference location to the defined external symbol; Has the same name as an external symbol defined in the object module When an external symbol to be defined is already defined in the main storage area, the address of the new external symbol is reset to a reference location to the already defined external symbol using the external symbol reference table. An external reference updating method characterized by the following.