JPH01205331A - Large-scale program link system - Google Patents

Abstract

PURPOSE:To reduce a work memory quantity at the time of linking by writing the content of the real address of an external symbol address table in an external symbol address table storage means at the time of storing a large-scale program in a memory. CONSTITUTION:A compile unit storage means 1 stores compile units consisting the large-scale program. A link command storage means 2 stores the names of the compile units and link commands holding attributes. A link means 3 sequentially fetches the compile units and the link commands, links the compile units and generates a definition symbol address table and an external symbol address table. A storage means 4 stores the large-scale program outputted as the result of a link result by the means 3. The storage means 5 stores the external symbol address table. A loading means 6 settles external symbol addresses in which association in the compile units are unsettled with collating the external symbol address table, and stores the program in the memory 8 in a form that the program can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a program linking method, and particularly to a linking method for large-scale programs such as operating systems.

[Conventional technology]

Conventionally, when linking multiple compilation units that make up a large-scale program such as an operating system, for example, the real addresses of external symbols that span between compilation units are determined within the large-scale program, and the compilation units are linked by symbols. When associating, when an external symbol whose real address is undetermined is confirmed in the first compilation unit, enter the second compilation unit in which the external symbol is defined and determine the real address of the external symbol. , Furthermore, when an external symbol whose real address is undetermined is recognized in the second compilation unit, the third compilation unit in which the external symbol has been determined is input, the real address of the external symbol is determined, and this operation is performed. Repeat until there are no external symbols whose real addresses are undefined,
The real addresses of all external symbols were determined and the compilation unit was linked.

[Problem to be solved by the invention]

In the conventional linking method described above, it is necessary to hold the compilation unit containing the external symbol in working memory until the address of the external symbol is determined, which makes it difficult for large-scale programs such as operating systems. The disadvantage is that linking requires a large amount of memory.

[Means to solve the problem]

The large-scale program linking method of the present invention stores a compilation unit storage means that stores a plurality of compilation units constituting a large-scale program, and a link command that stores the compilation unit name and attribute for each of the 131st compilations. a link command storage means, which takes in the compilation unit and the link command, linfts the compilation unit, and stores external symbols existing in the compilation unit, the real addresses of the symbols in the large-scale program, and the external symbols; A linking means for creating a definition symbol address table including a flag indicating whether a real address has been assigned or not, and an external symbol address table including an external symbol and a real address within a large-scale program corresponding to the external symbol, and a definition. Definition symbol address table storage means for storing a symbol address table; External symbol address table storage means for storing an external symbol address table; Large-scale program storage means for storing a large-scale program output as a result of linking by the linking means. , the memory that holds the large-scale program in an executable form and the real address of the large-scale program are fixed,
Detects an external symbol whose real address is not reflected in the corresponding compilation unit, refers to the external symbol address table, writes the real address of the external symbol to the compilation unit, and loads the large-scale program into the memory. and a loading means.

[Effect]

Specify a link command for each of the multiple compilation units that make up a large program, input the first compilation unit specified by the link command, and determine the real addresses of external symbols defined in the compilation unit. If you want to refer to an external symbol defined in another compilation unit, register it as an unresolved address in the definition symbol address table and refer to an external symbol defined in another compilation unit. By retaining the registration position of the corresponding external symbol in the definition symbol address table within the compilation unit, the working memory used in the first compilation unit is freed and the next compilation unit is linked. When the input of all compilation units is completed, the contents of the definition symbol address table are output as an external symbol address table, and unresolved external symbol addresses can be determined during large-scale program loading.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of the large-scale program linking method of the present invention, FIG. 2 is a diagram without the link command 21, and FIG. 3 shows the large-scale program 31 and the defined symbol address table 36. FIG. 4 is a flowchart that does not show the operation of the linking means 3 of FIG. 1.

The large-scale program linking method of this embodiment includes a compile unit storage means 1, a link command storage means 2, a link means 3, a large-scale program storage means 4, an external symbol address table storage means 5, a loading means 6, and a definition symbol address table. It is composed of storage means 7 and memory 8.

A compilation unit storage means 1 stores compilation units 1 to n that constitute a large-scale program. The link command storage means 2 stores a link command 21 that holds the compile unit name and attributes of each compile unit constituting a large-scale program. This link command 21
As shown in the figure, it is provided for each compilation unit 1 to n, and each holds the name and attributes of the compilation unit. The linking means 3 sequentially takes in the compilation unit and the link command 21 and links the compilation unit, and also links the external symbol existing in the compilation unit, the real address of the symbol in the large-scale program, and the external symbol. A defined symbol address table 36 including a flag indicating whether a real address has been assigned or not, and an external symbol address table including external symbols and real addresses within the large-scale program corresponding to the external symbols are created. In FIG. 3, the definition symbol address table 36 includes external symbols (Sl), real addresses (A1),
It consists of three items: flags (Fl), and is created to assign addresses to external symbols when linking compilation units. The program module 32 is a program module linked by the linking means 3.

The external symbol reference section 33 indicates the address of an external symbol within a program module each time a symbol appears, and is referenced by the linking means 3 when checking the presence or absence of an external symbol within the program module.

The symbol displacement index section 34 holds the displacement of the contents of the external symbol reference section 33. The address table displacement index section 35 corresponds to the external symbol held by the symbol displacement index section 34 and holds the position of the corresponding external symbol in the definition symbol address table 36 as a displacement of the definition symbol address table 36. . As shown in Table 1, the external symbol address table is composed of two items, external symbols and real addresses, and the recorded contents are the same as the contents of the external symbols and real addresses in the defined symbol address table described above.

The large-scale program storage means 4 stores the large-scale program output as a result of linking by the linking means 3. External symbol address table storage means 5 stores an external symbol address table. Definition symbol address table storage means 7 stores a definition symbol address table. Loading means 6
When loading a large-scale program, it resolves external symbol addresses that are included in the large-scale program and have unresolved associations between compilation units while referring to the external symbol address table, and stores the program in an executable form in memory 8. Load into.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 and 4.

First, the compilation units specified by the link commands stored in the link command storage means 2 are sequentially read from the compilation unit storage means 1 (step 211), and the external symbol reference section 33 checks whether the read compilation units have external symbols. (step 212), and if an external symbol exists, the external symbol is a reference y (or not, i.e. whether the symbol is defined in another part and is only referenced here), or , it is determined whether it is defined here (step 213).

If it is not a reference type, determine the actual address of the external symbol, and enter the external symbol name (S
1) and the confirmed real address (A1), turn on the flag (Fl) indicating that the real address corresponding to the external symbol is confirmed (step 219), and proceed to processing the next external symbol. . If the external symbol is a reference type as determined in step 213, the definition symbol address table 36 is referred to (step 214), and it is determined whether the external symbol is registered (step 215). Flag (Fl) corresponding to the symbol
is on (step 216). If the flag (Fl) is on, the real address has already been determined for this external symbol, and large-scale program 3
Write the real address (A1) to the external symbol reference section 33 of the program module 32 in 1 (step 217).
. If the flag (Fl) is not on as determined in step 216, the actual address (A
1) is not determined, the displacement of the external symbol reference section 33 is entered in the symbol displacement index section 34 of the program module 32, and the displacement of the corresponding external symbol in the defined symbol address table 36 is entered in the address table displacement index section 35. Enter the displacement in the definition symbol address table 36 (step 221
), move on to processing the next external symbol. If the corresponding external symbol is not found in the definition symbol address table 36 as determined in step 215, the external symbol (Sl) is registered in the definition symbol address table 36 and the corresponding flag (Fl) is turned off, and step 220 ), processes the next external symbol. When the processing of all external symbols in one compilation unit has been completed as determined in step 212, it is determined whether the processing of all compilation units has been completed (step 218). If it has not yet been completed, the working memory used in the linking process of the compilation unit is released (step 222), and the next compilation unit is processed; if it has been completed, the linking process is terminated.

At this time, the external symbol (Sl) and real address (A1) portions of the defined symbol address table 36 are output as the aforementioned external symbol address table. Next, when loading the large-scale program 31 into the memory 8, the external symbol reference section 33 of the program module 32 uses the real address (A1) in the external symbol address table 36 indicated by the index section 35.
By writing the contents of , unresolved external symbol references are resolved.

(Effect of the invention〕 As explained above, the present invention is a large-scale progera.

When linking programs, etc., specify a link command for each compilation unit that draws a large-scale program, input the first compilation unit specified by the link command, and link external files defined in the compilation unit. For symbols, determine the real address and register it in the definition symbol address table. For references to external symbols, register them as unresolved addresses in the definition symbol address table. The working memory used in the first compilation unit is freed by holding it in the form of a displacement in the definition symbol address table, the next compilation unit is linked, and all compilation units are When input is completed, the contents of the definition symbol address table are output as an external symbol address table, and unresolved external symbol addresses are resolved when loading a large program, greatly reducing the amount of working memory during linking. The effect is that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the large-scale program linking method of the present invention, FIG. 2 is a block diagram showing the link command 21 from t, and FIG. FIG. 4 is a flowchart 1 showing the operation of the linking means 3 of FIG. DESCRIPTION OF SYMBOLS 1... Compile unit storage means, 2... Link command storage means, 3... Link means, 4... Large-scale program storage means, 5... External symbol address table storage means, 6... Loading means, 7: Definition symbol address table storage means, 8: Memory, 21: Link command, 31: Large-scale program, 32: Program module, 33: External symbol reference section , 34... Symbol displacement index section, 35... Address table displacement index section, 36... Definition symbol address table, 211-222... Steps.

Claims (1)

[Claims] A large-scale program linking method for linking a large-scale program such as an operating system, comprising: a compilation unit storage unit storing a plurality of compilation units constituting the large-scale program; a link command storage means for storing a link command holding a compile unit name and attributes for each unit; a link command storage means that takes in the compile unit and the link command, links the compile unit, and stores external symbols existing in the compile unit; and the real address of the symbol in the large-scale program, a defined symbol address table containing a flag indicating whether a real address has been assigned to the external symbol, and the external symbol and the large-scale program corresponding to the external symbol. a linking means for creating an external symbol address table including real addresses of the external symbol address table; a defined symbol address table storing means for storing the defined symbol address table; an external symbol address table storing means for storing the external symbol address table; A large-scale program storage means for storing the large-scale program output as a result of linking, a memory for holding the large-scale program in an executable form, and a real address in the large-scale program has been determined,
Detects an external symbol whose real address is not reflected in the corresponding compilation unit, refers to the external symbol address table, writes the real address of the external symbol to the compilation unit, and loads the large-scale program into the memory. A large-scale program linking method having a loading means.