JPH02310627A - Link method for object program in language processing programming - Google Patents

Abstract

PURPOSE:To attain normal link by checking the branching range and the jumping destination of a branching instruction, and generating the other branching instruction in a range where branching is attained even if the jumping destination of the branching instruction is arranged beyond the range where branching is possible by the designation branching instruction and external reference is not settled. CONSTITUTION:In a link processing by a linker program, a checking function checks whether the jumping destination of the branching instruction is included in the range where branching is possible by the described branching instructions 24-1 to 24-4 and 26-1 to 26-5. When it is beyond the range, a generation function generates a new branching instruction which branches to the jumping destination of the designated branching instructions 24-1 to 24-4 to 26-1 to 26-5. Then, a correction function corrects the described branching instructions 24-1 to 24-4 and 26-1 to 26-5 to as to branch to the generated branching instruction. Even if the jumping destination of the described branching instructions 24-1 to 24-4 and 26-1 to 26-5 are beyond the range of the jumping destination of the designated branching instruction, normal link is attained, and an object which normally operates can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a linker for language processing programs, and in particular, after determining the placement of relocatable objects in segment units, which are the linker's placement unit specified at the time of assembly, The present invention relates to a method for creating an executable object program by modifying a part of the object program with reference to the located addresses.

When creating a program using a conventional technical language processing program, there is a way to use a program called a linker to combine multiple object programs or object modules into a final usable load module. be.

When linking such objects, if a relocatable object is linked and the jump destination of the branch instruction that is making the external reference falls outside the jump destination range of the specified branch instruction, normal linking will not be possible. . In this case, even if the objects are combined as is, the combined objects will not operate normally, so the linker outputs an error message and stops execution of the link process.

Problems to be Solved by the Invention As mentioned above, in the conventional linking method, when the jump destination of a branch instruction is located outside the branching range of the branch instruction as a result of linking relocatable objects, the process cannot be executed. had been discontinued.

If the execution of the link process is canceled for such reasons,
A program developer must search for a branch instruction contained in an object module, replace the branch instruction with another branch instruction with a wider branching range, and reassemble the source program. However, with this linking method, processing time until the linking process is interrupted is wasted, and the extremely time-consuming work of re-linking after modifying the source program and reassembling it is not necessary. No.

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned problems of the prior art, and provides a novel method that can link a program including a branch instruction whose jump destination is located outside the branchable range in a more efficient manner. Its purpose is to provide a convenient linking method.

Means for Solving the Problems According to the present invention, in a method for linking a relocatable object program on a computer system in which a language processing program operates, an external reference value is specified outside the branchable range of the program. Based on the external reference value of the extracted first branch instruction,
placed within a range that can be branched by the first branch instruction,
By generating a second branch instruction that can branch to an external reference value outside the range, and changing the branch destination of the first branch instruction to the location address of the second branch instruction,
Even if the branch destination of a branch instruction included in the program related to link processing is outside the branchable range of the branch instruction, the program is linked so as to create a program that can operate normally. A method for linking an object program is provided.

Effect: In the object program linking method according to the present invention, the linker program that performs the linking process is provided with a special function, thereby making it possible to automatically perform the linking process so that it operates normally even after linking. .

That is, in the method according to the present invention, the following three functions are provided to the link program.

■ Inspection function that checks whether the jump destination of the written branch instruction is included in the range that can be branched by the written branch instruction ■ The specified branch when the branch destination is outside the range that can be branched A generation function that generates a branch instruction that branches to the destination of the instruction ■ A modification function that modifies the written branch instruction so that it branches to the generated branch instruction. Checks whether the jump destination is included in the range that can be branched by the specified branch instruction, and if it is detected that it is outside the range, the generation function generates a new branch that branches to the jump destination of the specified branch instruction. Generate branch instructions. Next, the modification function modifies the written branch instruction so that it branches to this generated branch instruction, and thus the jump destination of the written branch instruction is outside the jump destination range of the specified branch instruction. Even in such cases, it is possible to link normally and create objects that operate normally.

That is, in contrast to the conventional linking method described above, in the method according to the present invention, when the jump destination of a written branch instruction is placed outside the branching range, the linker generates another branching instruction with a wider branching range. This automatically resolves external references and creates properly working object code. Therefore, link processing becomes very easy.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but the following disclosure is only one embodiment of the present invention, and does not limit the technical scope of the present invention in any way.

Embodiment 1 FIG. 1 is a flowchart showing the configuration of a linker that can be used to implement the method for linking object programs according to the present invention.

That is, as shown in FIG. 1, this linker creates a relocatable object file 1 to be linked
, a process 2 for determining the segment arrangement of this file, a process 3 for extracting external references to be resolved, and a process 4 for checking the remaining capacity of the unresolved branch instruction table in which the extracted external references are registered. The problem with external references is resolved by executing process 5, which generates a branch instruction to resolve external references, and process 6, which displays an error when other external references to be resolved occur. It is configured to output the object file 7 that has been created.

Here, the process 3 for extracting external references to be resolved has a function of checking whether the jump destination of the written branch instruction can be branched by the written branch instruction,
The extracted branch instructions to be resolved are registered in the unresolved branch instruction table.

Also, process 4 for checking the remaining amount of the unresolved branch instruction table.
has a function of changing the destination of a branch instruction to be processed to a new branch instruction that instructs a branch to the correct destination, which will be described later.

FIG. 2 is a flowchart that more specifically shows the functions of the linker shown in FIG. Detailed processing is shown for processing 5.

That is, as shown in FIG. 2, a process 3 for extracting external references to be resolved includes a process 8 for inspecting whether there are external references to be inspected, and as a result of the inspection, there are external references to be resolved. Processing 9 to check the integrity of this external reference if
As a result of this processing, processing 10 for resolving external references according to the reference type is repeated until there are no external references to be inspected. Here, in process 9, if a range error such that the reference destination address is outside the range is detected, process 11 is performed to check whether this external reference is due to a branch instruction, and Process 1 to register this in the unresolved branch instruction table if it is
2.

On the other hand, the process 5 of generating branch instructions for resolving external references first executes the process 13 of extracting branch instructions to be processed one by one from the unresolved branch instruction table, and then Process 1 to solve the problem of this branch instruction by using a new branch instruction that directs reference to an address
Execute 6. Here, in this embodiment, a process 14 for checking whether an already generated branch instruction can be used or not, and a process 15 for using this if it is available are added. Note that branch instruction resolution is performed by modifying the branch destination of the written branch instruction so that it branches to the generated branch instruction.

FIG. 3 is a diagram showing the arrangement of segments arranged in the segment arrangement determination process 2 in the memory space.

This memory space 17 has a size of 2000H (here, H
means hexadecimal number. Below, hexadecimal numbers are distinguished from decimal numbers by adding H to the end of the number), and the address is O.
IFFFH is assigned from H.

It is assumed that there is a boundary in the memory space 17 for each address 1000H, and objects cannot be placed across this boundary. There are two branch instructions: BRM branch instruction and BRL branch instruction.BRM branch instruction starts at address 1.
It is not possible to branch across the 000H boundary. On the other hand, a BRL branch instruction can branch to any address.

As shown in Figure 1, in a series of linker processes,
First, in the first process 2, the arrangement of segments is determined. That is, in the memory space 17, a segment A18, a segment B19, and a segment C20 are arranged.

Segment A18 has a size of 400H, and the symbols LBL22-1 and LBL are
It clearly indicates that B22-2 is externally referenced.

Segment B19 is of size C0OH, and the EXTRN pseudo-instruction 23 specifies that LBL22-1 and LBLB22-2 are to be externally referenced within the segment, and BRM
External references are made by branch instructions 24-C24-2, 24-3, and 24-4.

Segment C20 is of size C0OH (segment)
Similarly to B19, LBL is set by EXTRN pseudo-instruction 25.
22-1 and LBLB 22-2 are declared as external references, and the BRM branch instruction 262L26-2.26-3.
Externally referenced by 26-4 and 26-5.

FIG. 4 shows the results of external reference resolution according to the process shown in FIG.

That is, in FIG. 3, the BRM branch instructions 26-C26-2, 26-3, 26-4 and 26 of segment C20
-5 externally referenced LBL22-1 and LBL22-2 located outside the boundary of address 1000H. On the other hand, in the segment arrangement shown in FIG. 4, LBL22-1 and L B L B22-
BRL branch instructions 27-1 and 27-2 that branch to 2 are generated at addresses TBL28-1 and TBL828-2, and BRM branch instructions 26-C26-2, 26-3, 2 are generated at addresses TBL28-1 and TBL828-2.
The branch destination of 6-4 and 26-5 is set to TB according to the external reference destination.
It can be seen that L28-1 and TBLB2g-2 are used.

FIG. 5 is a diagram illustrating specific processing for obtaining the processing results shown in FIG. 4. That is, FIG. 5 is a diagram showing the inside of the table 29 used in the table registration process 12, the remaining amount checking process 4 of the unresolved branch instruction table, and the table element retrieval process 13.

Here, table 29 shows address 2 where a branch instruction whose external reference cannot be resolved by the written branch instruction is located.
9-1, a range 29-2 that can be branched by branch instructions that cannot resolve external references, and information regarding branch instructions that cannot resolve external references constituted by a designated branch destination 29-3.

Specifically, the processing here is executed as follows.

■ Manually create relocatable object files,
Segment A18 is determined by segment placement determination process 2.
, segment B19 and segment C20 are placed in the memory space 17. BR that is performing external reference at this time
M branch instructions 24-1.24-2.24-3.24-4 and BRM branch instructions 26-1, 26-2.26-3.2
The branch destination addresses of 6-4.26-'5 have not been determined.

■ In the process 3 of extracting external references to be resolved, first, the remaining amount of external references check process 8 searches for locations where external references are made from the beginning, and first discovers the BRM branch instruction 24-1. .

Next, by the consistency check process 9, the branch destination L B L22=
Since 1 is located within the boundary of address 100OH, it is determined that there is no problem and that the external reference can be resolved as is. Therefore, in the external reference resolution 10, the external reference is resolved using the location address of the LBL 22-1.

Similarly, BRM branch instruction 24-2.24-3.24-4
Resolve external references to .

(2) Next, unresolved external references are searched by the remaining amount of external references checking process 8, and the BRM branch instruction 26-1 is discovered.

The BRM branch instruction 26-1 is the same as the BRM branch instruction 24-1.
24-2. Unlike 24-3 and 24-4, the branch destination BL22-1 is outside the branch range of the BRM branch instruction 26-1. Therefore, the external reference cannot be resolved as it is, and the external reference format check 1 is performed by consistency check 9.
Enter 1.

According to external reference format check 11, this external reference is BR
Since this is an external reference by an M branch instruction, it is registered in the table in process 12, and the address where the BRM branch instruction 26-1 is located, the branch possible range, and the branch destination LBL are registered in the table in step 12.
22-1 is stored in the table 29 and the process returns to the segment arrangement determination processing section 2.

Similarly, BRM branch instruction 26 that cannot be placed as is.
-2.26-3.26-4 and 26-5 and their branch destinations LBL22-1 and LBLB22-2 are stored in the table 29. BRM branch instruction 26-5 in Table 2
After the unresolved branch instruction table is stored in the unresolved branch instruction table 9, since there are no more external references, an external reference remaining amount checking process 8 enters the unresolved branch instruction table remaining amount checking process 4.

(2) In the unresolved branch instruction table remaining amount checking process 4, it is checked whether or not there is an unresolved branch instruction stored in the table registration process 12. Here BRM branch instruction 26-1.26-2.26-3.26-
Since 4 and 26-5 are stored in the table 29 as having unresolved external references, branch instruction generation processing 5 is entered.

(2) In the branch instruction generation process 5, unresolved branch instructions are first extracted from the table 29 in the order in which they were stored in the table by the table element extraction process 13.

In this embodiment, first, the BRM branch instruction 26-1 is divided into the address 29-1 where it is placed and the branch possible range 29-2.
Then, the LBL 22-1, which is the branch destination 29-3, is taken out. Next, a process 14 of checking whether an already generated branch instruction is available is executed, and if a branch instruction has already been created, a branch with the same branch destination as the branch destination retrieved by table element retrieval 13 is executed. Check to see if the instruction has been generated. Since no branch instruction has been generated here, the process enters resolution processing 16 by generating a branch instruction.

■ By the resolution process 16 by branch instruction generation, the BRL branch instruction 27-1 whose branch destination is LBL 22-1 is
The address TBL 28 is generated within the branchable range of the RM branch instruction 24-1. Furthermore, the BRM branch instruction 26-
The branch destination of BRL branch instruction 27-1 is set to address TB of BRL branch instruction 27-1.
By setting L28-1, BRM branch instruction 26-1
external references are resolved.

Hereinafter, in the same way, the external reference of the BRM branch instruction, instruction 26-2, is changed to the BRL branch instruction 2 whose branch destination is LBLB22-2.
This problem can be solved by generating 7-2 at address TBL 828-2 and setting the branch destination of BRM branch instruction 26-2 to TBLB 28-2.

Next, the address 29-1 where the BRM branch instruction 24-3 is located, the branchable range 29-2, and the LBL 22-1 which is the branch destination 29-3 are extracted from the table 29 and solved. Here, the branch instruction to LBL22-1, which is the branch destination of the BRM branch instruction 24-3, has already been sent to TBL28-1.
is being generated. Therefore, the solution 15 using the already generated branch instruction is entered from the already generated branch instruction availability check process 14, and the BR is not generated without generating a new branch instruction.
This problem is solved by setting the branch destination of the M branch instruction 24-3 to the TBL 28-1.

Similarly, external references to BRM branch instructions 26-4 and 26-5 are resolved by setting the branch destinations of the respective branch instructions to TBL 28-1 and TBL 82g-2.

By the linker performing the above processing, even if the branch destination of the written branch instruction is located outside the branching range of the written branch instruction, it is possible to link normally, and the linking As a result, a properly operating object program is obtained.

Example 2 In Example 1 described above, one branch instruction is generated and used for branch instructions that branch to the same branch destination, but one branch instruction is generated and used for one external reference. You can also.

FIG. 6 is a flowchart illustrating processing of such a method. That is, in contrast to the processing performed in the first embodiment shown in detail in FIG. 2, in the processing according to the present embodiment, processing for checking whether or not an already generated branch instruction can be used is not performed.

Although this method increases the size of the created object, it simplifies linker processing, and by modifying the object file after linking, it is possible to change only the branch destination of a specific branch instruction. It becomes possible.

FIG. 7 is a diagram showing the result of resolving external references using the branch instruction generation means shown in FIG. 6, in comparison with FIG. 4.

Here, the BRM branch instruction 26-L26-2.26-3.2 cannot resolve external references without generating a branch instruction.
6-4 and 26-5, respectively, BRL branch instructions 27-L27-2.27-3.27-4 and 27-
5 is generated and the BRM branch instruction 26-1゜26-2.2
The branch destination of 6-3.26-4 and 26-5 is also the generated BRL branch instruction 27-1.27-2.27-3.27
-4 and 27-5 respective addresses TBL28-
1, TBL828-2, TBLC28-3, TBLD2
It has been changed to 8-4 Heat and TBLE28-5.

Hereinafter, the processing process leading to such a processing result will be explained step by step.

■ Manually create relocatable object files,
Segment A18 is determined by segment placement determination process 2.
, segment B19 and segment C20 are placed in the memory space 17. Subsequently, the process of storing unresolvable branch instructions in a table by external reference extraction process 3 is the same as in the first embodiment described above.

■ Next, unresolved branch instruction table remaining capacity check processing 4
Process 4 is performed to check whether the branch instruction to be processed is stored in the table.

■ If an unresolved branch instruction is stored in the table, branch instruction generation processing 5 is entered.

In this embodiment, the branch instruction generation process 16 always generates one new branch instruction for each unresolved branch. Here, in the branch instruction generation process 5, a process 13 is performed to take out the unresolved branch instructions stored in the table one by one, and in this embodiment, the BRM branch instruction 26-1 stored first is , the located address 29-1, branch possible range 29-2, and branch destination 29-3
Obtaining LBL22-1, BRM branch instruction 26-1
A BRL branch instruction 27-1 to the branch destination LBL 22-1 is generated at the address TBL 28-1 that is within the branchable range of
Make it.

Similarly, for BRM branch instruction 26-2, TBL
Create BRL branch instruction 27-2 in 828-2 and execute BRM
The branch destination of the branch instruction 26-2 is set to TBL 828-2. Below, BRM branch instruction 26-3.26-4.26-
5, the BRL branch instruction 27-3.27
-4 and 27-5 to address TBLC28-3, TB
Created on LD28-4 and TBL E28-5.

Through the above processing, as shown in FIG. 7, an object program is completed in which branch instructions corresponding to each branch instruction are placed in the same segment and external references are resolved.

As described in detail, according to the linking method of the present invention,
Before joining objects, check the branch range and jump destination of the branch instruction, and if the jump destination of the branch instruction is placed outside the range that can be branched by the specified branch instruction, and external references cannot be resolved as is. However, by generating another branch instruction within the branchable range, it is possible to perform normal linking.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the process performed by the method according to the present invention, FIG. 2 is a flowchart showing the specific process for implementing the method shown in the first part, and the third The figure is a diagram showing the arrangement of segments in the memory space before the segment arrangement is determined by process 2 and external references are resolved among the processes shown in Fig. 1. FIG. 5 is a diagram showing the arrangement of segments in memory space after external references are resolved by the process in step 1, and FIG. 5 shows the structure of a table used when implementing the method shown in FIG. 1. FIG. 6 is a flowchart showing other specific processing for carrying out the present invention, and FIG. FIG. 3 is a diagram showing the arrangement of segments in a memory space. [Main reference numbers] ■... Relocatable object, 2... Segment placement determination process, 3... External reference resolution process, 4... Unresolved branch instruction table remaining capacity check process, 5...
Processing to generate a branch instruction, 6... Error processing unit, 7... Address resolved object, 8... Remaining amount of external reference checking processing, 9... Consistency checking processing, IO... External reference resolution, 11... Format check of external reference, 12... Registration in table, 13... Retrieval of table element, 14... Usability check process of generated branch instruction, 15...
Solution using generated branch instructions, 16... Solution by generating branch instructions, 17... Memory space 18... Segment A19...
Segment B 20...Segment C2■...PUB
LIC pseudo-instruction 22-1...LBL, BRM branch instruction 24-1.24-
Address 22-2 externally referenced by 2.24-4.26-1.26-3.26-4...LBLB, BRM branch instruction 24-3゜26
-2, Address 23 externally referenced by 26-5...EXTRN pseudo-instruction 24-1.24-2.24-3.24-4.24-5.
・BRM branch instruction 25・・EXTRN pseudo-instruction 26-1.26-2.26-3.26-4.26-5・
・BRM branch instruction 27-1.27-2.27-3.27-4.27-5・
・BRL branch instruction 28-1...Address 28-2 where TBL, BRL branch instruction 27-1 was generated...Address 28-3 where TBLB, BRL branch instruction 27-2 was generated...TBLC, BRL branch instruction Address 28-4 where 27-3 was generated... Address 28-5 where TBLD, BRL branch instruction 27-4 was generated... Address 29 where TBLE, BRL branch instruction 27-5 was generated... Table 29- 1. Address where the written branch instruction is located 29-2. Range that can be branched by the written branch instruction 29-3. Branch destination of the written branch instruction.

Claims (1)

[Scope of Claim] A method for linking a relocatable object program on a computer system in which a language processing program operates, the method comprising: extracting a branch instruction whose external reference value is specified outside its own branchable range; Based on the external reference value of the first branch instruction, the second branch instruction is placed within a range that can be branched by the first branch instruction and is capable of branching to an external reference value outside the range; In addition, the branch destination of the first branch instruction is set to the branch destination of the first branch instruction.
By changing the location address of the branch instruction, create a program that can operate normally even if the branch destination of the branch instruction included in the program related to link processing is outside the branchable range of the branch instruction. A method for linking an object program, characterized in that the program is linked as follows.