Program conversion apparatus, program conversion method, and computer program for executing program conversion process

A program conversion method targeting a processor that includes a compiler and a linker for compiling a first source program that describes an external entry into a first machine instruction sequence and a second source program that describes a branch procedure to the external entry into a second machine instruction sequence, and linking a plurality of machine instruction sequences including the first and second machine instruction sequences, to generate an executable program, each of the first and second machine instruction sequences being composed of one or more machine instructions that each belong to one of the instruction sets, the program conversion method comprising:

• a first-instruction-set-information generating step, performed by the compiler, of generating first-instruction-set-information when the first source program is compiled, the first-instruction-set-information showing an instruction set to which a machine instruction for executing a procedure described at the external entry belongs;
• an-indefinite-branch-information generating step, performed by the compiler, of generating indefinite-branch-information when the second source program is compiled, the indefinite-branch-information showing a location at which a branch instruction for executing the branch procedure is to be placed, and showing that an instruction set to which a machine instruction placed at the external entry belongs is indefinite;
• a branch instruction generating step, performed by the linker, of generating the branch instruction for executing the branch procedure, by using a branch-with-mode-change instruction for making the processor select the instruction set shown by the first-instruction-set-information, at the location shown by the indefinite-branch-information, when the plurality of machine instruction sequences are linked;
• and
• a processing step of dynamically selecting one of a plurality of instruction sets by executing a branch-with-mode-change instruction and interpreting and executing a machine instruction according to the selected instruction set.

A computer-readable medium storing therein a computer program for executing, using a computer, a program conversion process targeting a processor for compiling a first source program that describes an external entry into a first machine instruction sequence and a second source program that describes a branch procedure to the external entry into a second machine instruction sequence, and linking a plurality of machine instruction sequences including the first and second machine instruction sequences, to generate an executable program, each of the first and second machine instruction sequences being composed of one or more machine instructions that each belong to one of the instruction sets, the computer program comprising:

• a first-instruction-set-information generating step, performed by the compiler, of generating first-instruction-set-information when the first source program is compiled, the first-instruction-set-information showing an instruction set to which a machine instruction for executing a procedure described at the external entry belongs;
• an indefinite-branch-information generating step, performed by the compiler, of generating indefinite-branch-information when the second source program is compiled, the indefinite-branch-information showing a location at which a branch instruction for executing the branch procedure is to be placed, and showing that an instruction set to which a machine instruction placed at the external entry belongs is indefinite;
• a branch instruction generating step, performed by the linker, of generating the branch instruction for executing the branch procedure, by using a branch-with-mode-change instruction for making the processor select the instruction set shown by the first-instruction-set-information, at the location shown by the indefinite-branch-information, when the plurality of machine instruction sequences are linked;
• and
• a processing step of dynamically selecting one of a plurality of instruction sets by executing a branch-with-mode-change instruction and interpreting and executing a machine instruction according to the selected instruction set.

A program conversion apparatus that generates object code modules comprising:

• a memory storing
• (i) a compiling unit that includes:
• a machine-instruction-sequence generating unit that generates object code, an instruction-set-information generating unit that generates entry point information for the object code,
• a branch-information-generating unit that associates pseudo branch instructions in an assembler program with machine code addresses to generate an indefinite branch table showing that an instruction set to which a machine instruction placed at a branch destination belongs is indefinite, and
• an indefinite-branch-information generating unit operable to generate indefinite-branch-information when a source program is compiled, the indefinite-branch-information showing a location at which a branch instruction for executing the branch procedure is to be placed, and showing that an instruction set to which a machine instruction placed at the external entry belongs is indefinite;
• and
• (ii) a linking unit that links object code generated by the machine-instruction-sequence generating unit, the linking unit having a branch-instruction generating unit that generates branch instructions using entry point information generated by the instruction-set-generating unit and the indefinite branch table generated by the branch-information-generating unit;
• and
• a processor operable to execute the compiling unit and the linking unit by selecting one of a plurality of instruction sets, executing a branch-with-mode-change instruction, and interpreting and executing a machine instruction according to the selected instruction set.

A computer based method for compiling and linking machine code, comprising the steps of:

• compiling a first source program into a first machine code instruction sequence;
• associated with the first machine code sequence;
• compiling a second source program into a second machine code instruction sequence;
• generating indefinite-branch-information associated with a branching instruction in the second machine code instruction sequence when the second source program is compiled, the indefinite-branch-information showing a location at which a branch instruction for executing the branch procedure is to be placed, and showing that an instruction set to which a machine instruction placed at the external entry belongs is indefinite;
• and
• linking the first machine code instruction sequence to the second machine code instruction sequence by inserting a branch-with-mode-change instruction between the first machine code instruction sequence and the second machine code instruction sequence when the branch instruction information and the external entry information show that a mode change is needed.