JPH0561673A - Dynamic link system for object program - Google Patents

Abstract

PURPOSE:To make it possible to branch a branch instruction included in an object program dynamically written in a memory and limited at its branch enabled range to the outside of the branch enabled range. CONSTITUTION:When processing 101 for judging whether a branched address of a branch instruction is included in the branch enabled range of the branch instruction or not judges that the branched address is outside the range, the leading address of an instruction string formed by processing 121 for forming the instruction string for changing branch to the original branched address to the branch enabled range of the branch instruction is set up in the branch instruction by processing 122 for setting up the branch instruction so as to be branched to the instruction string formed by the processing 121.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of dynamically linking an object program, which dynamically reads the object program into a memory during execution of the program and performs reference resolution.

[0002]

2. Description of the Related Art In the conventional dynamic linking method of an object program, when performing reference resolution, a branch is made to the branch destination as it is.

[0003]

In the conventional dynamic linking method of the conventional object program described above, for example, the instruction part of the program starts at the address 0x400000, the data part starts at the address 0x10000000, and the object program is dynamically read. Is read in the data part, and the branchable range of the branch instruction generated by the compiler is limited to the 256-megabyte address space containing the branch instruction (Fig. 2), the dynamic reading in the data part is performed. However, the procedure in the instruction part could not be called from the branch instruction in the object program.

An object of the present invention is to make it possible to call an arbitrary procedure even in the above case.

[0005]

The dynamic linking method of an object program according to the present invention, during execution of the program,
Dynamically load the object program into memory,
In the dynamic linking method of the object program that performs reference resolution so that the read program can be called as a sub routine, the branchable range judgment that determines whether the branch destination of the branch instruction is within the branchable range of the branch instruction Means, and first reference resolution means for performing reference resolution so as to branch from the branch instruction to the branch destination when the branch destination of the branch instruction is within the branchable range of the branch instruction.
If the branch destination of the branch instruction is not within the branchable range of the branch instruction, a branchable instruction up to the branch destination is generated within the branchable range of the object program, and a branch destination is generated. A second reference solving means for performing reference resolution so as to branch from the specified instruction, and performing reference resolution so as to branch to the generated instruction from the branch instruction in the object program.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a dynamic linking method of an object program according to the present invention will be described with reference to the drawings.

FIG. 1 shows a flow chart of an embodiment of the present invention.

In FIG. 1, the dynamic link method is a process 1
In 01, it is checked whether the branch destination of the branch instruction is within the branchable range of the branch instruction.
If it is out of the range, the process 120 is selected.

First, the processing 110 when the branch destination is within the branchable range of the branch instruction will be described. The process 110 simply sets the branch destination address to the branch destination address of the branch instruction. For example, in the program of FIG. 3A, if the branch destination 302 of the branch instruction 301 is within the branchable range of the branch instruction 301, the branch instruction 301 is the same as the instruction 311 of FIG. Become.

Next, the processing 120 when the branch destination is out of the branchable range of the branch instruction will be described. In the process 120, first, in the process 121, the instruction sequence of FIG. 4 is generated within the branchable range of the branch instruction.

Here, the instruction 401 is an instruction for fetching the designated address into the designated register, that is, the instruction 402.
Is a branch instruction capable of branching to an arbitrary address with the content of the specified register as the branch destination address.

Next, in process 122, the address of the instruction sequence generated in process 121 is set to the branch destination address of the branch instruction. For example, in the program of FIG. 3A, when the branch destination 302 of the branch instruction 301 is outside the branchable range of the branch instruction 301, the branch instruction 301 becomes 321 after the processing 120, and the instruction generated in the processing 121. 32 rows
3,324. Here, the instruction 323 is the branch instruction 32.
It is placed within the branchable range of 1.

The operation at the time of execution of the dynamically linked program will be described with reference to the operation shown in FIG. 3 and the instruction sequence shown in FIG.

First, the operation when the branch destination is within the branchable range of the branch instruction will be described with reference to the instruction sequence of FIG. The branch destination 312 of the branch instruction 311 is the branch instruction 311.
The branch instruction 311 simply branches to the branch destination 312 because it is within the possible branch range.

Next, the operation when the branch destination is outside the branchable range of the branch instruction will be described with reference to the instruction sequence of FIG. Since the original branch destination 322 of the branch instruction 321 is outside the branchable range of the branch instruction 321, the branch instruction 321 cannot branch.

Therefore, the branch instruction 321 first executes the process 12
1 branches to the instruction 323 generated by 1. The instruction 323 fetches the address of the original branch destination 322 of the branch instruction 321 into a register. Next, by branching from the instruction 324 to the address fetched by the instruction 323 into the register, the branch instruction 3
The branch from 21 to the branch destination 321 is completed.

[0017]

According to the present invention, even if the branching range of the branch instruction in the object program dynamically read into the memory is limited, the procedure outside the branching range can be called. ..

[Brief description of drawings]

FIG. 1 shows a flow chart of an embodiment of the present invention.

FIG. 2 is a memory layout diagram of an example used in the description of the related art.

FIG. 3 shows a list of object programs used to describe an embodiment of the present invention.

FIG. 4 shows a list of instruction sequences generated in processing 121 of FIG.

Claims (1)

[Claims] 1. A branch of a branch instruction in a dynamic linking method of an object program, which dynamically reads an object program into a memory during execution of the program and performs reference resolution so that the read program can be called as a sub routine. A branchable range determining means for determining whether the destination is within the branchable range of the branch instruction, and a branching destination from the branch instruction when the branch destination of the branch instruction is within the branchable range of the branch instruction. A first reference resolution means for performing reference resolution so as to branch to a branch instruction; and, if the branch destination of the branch instruction is not within the branchable range of the branch instruction, within the branchable range of the branch instruction in the object program, An object program that generates instructions that can branch to the branch destination and performs reference resolution to branch from the generated instructions to the branch destination. A dynamic linking method for an object program, comprising: second reference resolution means for performing reference resolution so as to branch from a branch instruction to a generated instruction.