JPH03158931A - Link method for execution form program - Google Patents

Abstract

PURPOSE:To shorten the link time by utilizing a link address obtained at the time of link executed previously, in the case of re-executing newly a link after the link is executed once. CONSTITUTION:At the time of link, a section table 70 and a symbol list table 80 are generated first. Subsequently, that which is defined by a discriminating information item 82 of the symbol list table 80 is recognized first, a symbol table 90 is generated and it is contrived to settle a symbol name in an original form data block 14. Therefore, an item whose reference is shown by the discriminating information item 82 of the symbol list table 80 s recognized, and also, the contents of an address item 83 and a link address item 92 are compared. Accordingly, as for a symbol name in which the contents of the link address item 92 and the address item 83 coincide with each other, it is possible to omit a processing for writing a link address. In such a way, the link is ended at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for linking an executable program by linking relative format modules to obtain an executable program.

(Prior Art) In order to efficiently develop programs and provide flexibility, it is desirable to create relocatable programs for each module (function). A relocatable program is a program that has not yet decided where to place it in memory at the time of developing and compiling it, and is eventually created by linkage editor etc. The address to be placed there can be determined (link).

Generally, a relocatable program is called a relative format module, and a program linked using a linkage editor or the like is called an executable program.

Here, we will discuss how to link executable programs to obtain one executable program by linking multiple relative format modules using a linkage editor or the like.

FIG. 2 shows a conceptual diagram of a boat fishing link method.

First, it is assumed that three relative format modules 2, 3.4, which have already been compiled, are input to the linkage editor l. The linkage editor 1 performs the process (linking) of generating one executable program 5 from these relative format modules.

By the way, when linking relative format module 2.3.4, symbolic addresses (symbol names) must be resolved. That is, it is necessary to convert the symbol name into a concrete address (absolute address on the executable program). Therefore, during compilation, the relative format module is provided with relocation information that indicates where the symbol name exists in the original data (compiled source program).

FIG. 3 shows a configuration diagram of the relative format module.

The relative format module 2 is composed of five elements: a file header 12, a section ladder 13, an original data block 14, relocation information 15, and a symbol table 16.

The file ladder 12 is composed of a section header number item 21 indicating the number of section header ladders 13, and a symbol table position item 22 indicating the position of the symbol table in the relative format module 2.

The section ladder 13 is composed of an original data position item 31 and a relocation information position item 33 indicating the positions of the original data block 14 and relocation information 15 in the relative format module 2. Note that, when there is a plurality of relocation information 15, a plurality of relocation information position items 33 are provided corresponding to the plurality of relocation information 15.

The original data block 14 is a block consisting of machine language (original data) based on a source program. Note that a blank space (for example, °'oo'') is stored in the part corresponding to the symbol name in this block.

The relocation information 15 is composed of a modification position item 51 indicating the position of the symbol name in the original data block 14, and a symbol table position item 52 indicating a predetermined position in the symbol table 16 corresponding to this modification position item 51. . This relocation information 15 is provided corresponding to a reference symbol name, which will be explained later, and if a plurality of reference symbol names exist in the original data block 14, a plurality of items of location information 15 are also provided.

The symbol table 16 includes a symbol name field 61 indicating the symbol name existing in the original data block 14, and whether this symbol name is defined in the original data block or in the original data block of another relative format module. Identification information item 62 indicating whether to refer to something defined in
and an address item 63 indicating the position on the original data block 14 where the symbol name is placed (only in the case of a defined symbol name). The contents of this symbol table 16 are:
Each item is provided for each symbol name, that is, corresponding to the number of symbol names existing in the original data block 14.

Now, in the original data block 14, symbol names exist as described above. There are two types of symbol names: definition and reference. The symbol name of the definition refers to the symbol name defined in the original data block 14 of the relative format module 2. Also, the symbol name of the reference is
A symbol name defined in a relative format module 3 or 4 other than the relative format module 2, and when the relative format module 2 (original data block 14) uses the symbol name of this reference, other relative format modules It is called this way because it refers to the symbol name inside.

By the way, the relocation information position item 33 and the modification position item 51 of the relocation information 15 are provided in one-to-one correspondence. The relocation information position item 33 and the relocation information 15 are provided only for reference symbol names in the original data block 14.

On the other hand, each item in the symbol table 16 corresponds to the original data block 14.
It is provided corresponding to all the symbol names inside. Regarding the content of the address item 63, in the case of a definition symbol name, a module address indicating the position in the original data block 14 is stored.

Now, FIG. 4 shows an explanatory diagram of a conventional linking method.

The figure shows linkage editor 1 and relative format module 2.
, 3.4 and executable program 5 are shown. Although the internal configuration of only the relative format module 2 is shown, the same applies to the relative format modules 3.4.

First, the linkage editor 1 reads the ladder 12 into the file of the relative format module 2 and recognizes the section header number item 21 and the symbol table position item 22. This results in section header 13 of relative format module 2.
and symbol table 16 can be recognized. Furthermore, linkage editor 1 adds section ladder 13 and symbol table 1
6, and section table 70 (original data position item 71, relocation information position item 73, symbol table pointer item 74) and symbol table table 80.
(Symbol table pointer item 81, identification information item 82, address item 83) are generated. Here, the symbol table pointer item 74 newly generated within the linkage editor 1 is an item that stores an address indicating the position of the symbol table table 80 within the linkage editor 1. Also, symbol table pointer item 8
1 is an item that stores an address pointing to a specific position in the symbol table 90, which will be explained later.

Now, the linkage editor l will create a symbol table 90 corresponding to the symbol table table 80 by referring to the relocation information position item 73.

First, when generating the symbol table table 8o, the content of the symbol name item 61 corresponding to the item of the symbol table pointer item 81 is converted into numerical information, and the hash table 75 is referred to. As a result, a predetermined address is generated, and if there is no item in the symbol table 90 corresponding to this address, a symbol table pointer item 91 and a link address item 9 are generated.
Generate 2. The symbol table pointer item 91 is an item that stores an address that specifies the symbol table table 80 in which symbol names managed by this symbol table 90 are defined. The link address item 92 is an item that stores an address indicating a position where a defined symbol name is placed on the executable program 5.

The process of generating the symbol table 90 generates the contents of the symbol table 90 when the identification information item 82 of the symbol table table 80 indicates a definition. Further, when the identification information item 82 indicates reference, only the symbol table pointer item 91 and link address item 92 are secured if the symbol table 90 has not been generated.

A symbol table is similarly created for relative format module 3.4. Once all symbol tables have been created, the linkage editor determines the address for each symbol.

Thereafter, the linkage editor reads the original data of the relative format module, modifies it with the determined link address (absolute address), and outputs the original data to a predetermined position in the executable program 5. When reading, modifying, and outputting the original data for all relative format modules is completed, the link ends.

(Problems to be Solved by the Invention) When the executable program 5 is actually operated, problems often arise. In this case, the linked relative format module (source program) is changed, the modified source program is compiled again, and the link is redone using the procedure described above.

At the time of this new link, even if the change in the program was trivial, link processing was performed on all relative format modules to be linked from the beginning.

That is, from the creation of the symbol table 90, reading, modification, and output of original form 0 data are performed for all symbol names. However, the modification result of the original data is
That is, the content of the link address is almost unchanged from the previous link. This is because in most cases, changes to the program are limited to only a few modifications and have little effect on other modules. For this reason, even though the link result hardly changes, very time-consuming processes such as modifying the link address of the original data are forced, and it is difficult to easily create the executable program 5 and run it quickly. This was an obstacle to working efficiently.

Furthermore, since there are generally many modifications to the original data, this also places a burden on the hardware that performs this modification.

The present invention has been made with attention to the above points. The object of the present invention is to provide a method for linking executable programs that can quickly terminate linking by using a link address.

(Means for Solving the Problems) The method for linking an executable program of the present invention is such that when an executable program is obtained by linking a plurality of relative format modules containing original data that are compiled programs, Write the link address and
If you have already completed the link and are referring to it, and you modify any of the relative format modules and perform the link again, the new link address generated in the linkage editor will be changed to the relative format. It is characterized in that it compares the link address already written in each original data of the module, writes a new link address into the original data only if they do not match, and uses each original data as is if they match. It is something.

(Operation) In the above method, when an executable program is obtained by linking multiple relative format modules 1 containing original data that are compiled programs, each relative format module is given the symbol name resolved at the time of linking. Write the link address indicating the location in the executable program where the file should be placed. When linking is performed again, the link address newly generated in the linkage editor and to be written in the original data is compared with the link address already written in each original data of the relative format module. However, only if there is a mismatch, a new link address is written into the original data.

(Example) FIG. 1 shows an explanatory diagram of a linking method according to the present invention.

The diagram is basically the same as that previously described in FIG. 4. Therefore, the same parts are given the same reference numerals, and redundant explanations will be omitted as appropriate.

In the section ladder 13 of the relative format module 2, original format and data link position items 32 are newly provided. This original data link position item 2 32 is an item that stores a link position (address) indicating at which position on the executable program 5 the original data block 14 is copied to the executable program 5. be.

Also, in the address field 63 of the symbol table 16, the symbol table table 80 is
The contents of the address field 83 are written.

First, the linkage editor 1 reads the ladder 12 into the file of the relative format module 2 and recognizes the section header number item 21 and the symbol table position item 22. This will take you to the relative format module 2 section Ladder 13
and symbol table 16 can be recognized. Furthermore, linkage editor 1 adds section ladder 13 and symbol table 1
6 and copy section table 70 (original data position item 71, original data link position item 72, relocation information position item 73, symbol table pointer item 74) and symbol table table 8° (symbol table pointer item 81, Identification information 3 4 item 82 and address item 83) are generated.

Now, the linkage editor 1 refers to the relocation information position item 73 to create a symbol table 90 corresponding to the symbol table table 80.

At this time, first, a process is performed to generate the symbol table 90 only for items whose contents in the identification information item 82 indicate definitions.

To create the symbol table 90, when creating the symbol table table 80, the contents of the symbol name item 61 corresponding to the item of the symbol table pointer item 81 are converted into numerical information, and the hash table 75 is referred to. As a result, a predetermined address is generated, and if there is no item in the symbol table 90 corresponding to this address, the symbol table pointer item 91
and a link address item 92 is generated. The symbol table pointer item 91 is an item that stores an address specifying the symbol table table 80 in which symbol names managed by this symbol table are defined. The link address item 92 is an item that stores an address indicating a position where a defined symbol name is placed on the executable program 5.

After creating the symbol table 90 corresponding to the item for which the contents of the identification information item 82 indicate the definition, the identification information item 8
The symbol table 90 is referred to for the item for which the content of 2 indicates reference. In this case, address item 83 and link address item 92 are first compared. Only if this results in a mismatch, the link address in the link address field 92 is written to the address field 83 and further written to the position of the corresponding symbol name in the original data block 14. Then, by allocating link addresses to all symbol names in the original data block 14,
This means that the symbol name resolution processing for relative format module 2 has been completed. After resolving the symbol name, the linkage editor 1 writes the contents of the address item 83 of the symbol table table 80 to the address item 63 of the symbol table 16. The symbol name is resolved using the same procedure for the relative format module 3.4.

5 After the linkage editor 1 resolves symbol names for all relative format modules to be linked, the linkage editor 1 then creates an executable program 5 that copies the original data block 14.
Determine the upper position (original data link position). Then, it is compared with the contents of the original data link position item 72. If the result of this comparison is a mismatch, the contents of the original form data link position item 72 are rewritten, and the contents of the original form data link position item 32 of the ladder 13 to the section are also rewritten. Then, the linkage editor 1 copies the original data in each device format module to a predetermined position in the executable format program 5, and completes the linkage.

Now, if any problem occurs when you actually run executable program 5, change the relative format module (source program) that was linked, compile the modified source program again, and continue. You will need to redo the link using the steps described in .

1, the section table 70 and symbol table table 80 are first generated. Then, only those whose definitions are indicated by the identification information items 82 of the symbol table table 80 are recognized first, and a symbol table 90 is created to resolve the symbol names in the original data block 14. Thereafter, the item to which the identification information item 82 of the symbol table table 80 indicates the reference is recognized, and the address item 8
3 and the contents of the link address item 92 are compared. As a result, the contents of the link address item 92 are written into the address item 83 only for items that do not match, and are further written into the position of the corresponding symbol name in the original data block 14.

That is, for symbol names whose contents in the link address field 92 and the address field 83 match, the process of writing the link address is omitted. This is because the link address from the previous link remains in the address field 63 of the symbol table 16, and can be used when creating a new link. Note that the fact that the link address remains in the address field 63 of the symbol table 16 means that the link address also remains in the corresponding location in the original data block 14.

Next, when the symbol name in the original data block 14 and the symbol name in the relative format module 3.4 are also resolved, the position on the executable program 5 where the original data block 14 is to be copied is determined, and the original data link position item 72 is determined. Compare with the contents of If the result of this comparison is a mismatch, the content of the original form data link position item 72 of the section table 70 is rewritten as described above, and
Furthermore, the contents of the original form data link position item 32 are rewritten.

Note that the fact that the determined original data link position and the content of the original data link position item 72 match means that the original data block I4 should be copied to the same location of the executable program 5 as in the previous link. means.

Finally, the original data block 14 is copied onto the executable one-line program 5 to complete the linking.

As mentioned above, link history in relative format module 2,
That is, the link address and the like are left, and when creating a new link, it is determined whether this ring address can be used or not, and if it can be used, the information for the original data block 14 is used as is.

(Effects of the Invention) The method for linking an executable program of the present invention described above is as follows: - When linking is executed once and then a new link is to be performed, the link address obtained during the previous link is used. Therefore, the link time can be shortened. Therefore, an executable program can be obtained quickly. Further, since processing such as link address modification in the original data block is significantly reduced, the burden on the hardware can be reduced.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the linking method according to the present invention, Fig. 2 is a conceptual diagram of a general linking method, Fig. 3 is a configuration diagram of a relative format module, and Fig. 4 is a diagram of the conventional linking method. It is an explanatory diagram. 1... Linkage editor, 2.3.4... Relative format module, 5... Executable format program, 12... File header, 13... Section header, 14... Original data block, 15 ...Relocation information, 16...Symbol clothing, 7
0...Section table, 75...Hatsh table,
80...Symbol table, 90...Symbol table.

Claims (1)

[Claims] When an executable program is obtained by linking a plurality of relative format modules including original data, which are compiled programs, a link address is written in the original data, and the linking has already been completed. When you modify any of the relative format modules and perform the link again, the new link address generated in the linkage editor is added to each original format of the relative format module. A method for linking an executable program, characterized in that the link address is compared with a link address already written in the data, and only if there is a mismatch, a new link address is written in the original data.