7. A computer system for analyzing a control flow graph by an abstract interpretation of a program, the computer system comprising a non-transitory storage memory and a processor for executing a computer program tangibly loaded in the memory, the computer program comprising the program codes of: extracting a program state of the program from a program state buffer, the program state including a program counter; generating an edge of a control flow graph from a branch instruction associated with the program counter to a target address of the branch instruction in an abstract interpretation for an assignment instruction to a branch target variable of a program; the program allocating a particular branch target variable to each branch instruction having a plurality of branch targets configured to store branch target addresses of each of the plurality of branch targets, with a branch target address for one of the plurality of branch targets being loaded from the branch target variable upon branching; a branch address of a branch instruction having one branch target as well as the target address assigned by the assignment instruction to the branch target variable being determined as certain constant values determined by compiling the program; adding the target address assigned by the assignment instruction to a program counter of a new program state of the abstract interpretation, and setting a flag for the particular program counter associated with the branch instruction; and terminating a current abstract interpretation in the case that the abstract interpretation reaches to program state already subjected to the abstract interpretation, as indicated by a flag set for a program state.
7. A computer system for analyzing a control flow graph by an abstract interpretation of a program, the computer system comprising a non-transitory storage memory and a processor for executing a computer program tangibly loaded in the memory, the computer program comprising the program codes of: extracting a program state of the program from a program state buffer, the program state including a program counter; generating an edge of a control flow graph from a branch instruction associated with the program counter to a target address of the branch instruction in an abstract interpretation for an assignment instruction to a branch target variable of a program; the program allocating a particular branch target variable to each branch instruction having a plurality of branch targets configured to store branch target addresses of each of the plurality of branch targets, with a branch target address for one of the plurality of branch targets being loaded from the branch target variable upon branching; a branch address of a branch instruction having one branch target as well as the target address assigned by the assignment instruction to the branch target variable being determined as certain constant values determined by compiling the program; adding the target address assigned by the assignment instruction to a program counter of a new program state of the abstract interpretation, and setting a flag for the particular program counter associated with the branch instruction; and terminating a current abstract interpretation in the case that the abstract interpretation reaches to program state already subjected to the abstract interpretation, as indicated by a flag set for a program state. 9. The computer system of claim 7 , further comprising the program codes of: copying an address of the program counter and a virtual address for performing the abstract interpretation to a memory; and deleting the copied program counter and the copied virtual address from the memory in a first-in-last-out scheme by completion of the abstract interpretation of the corresponding instruction.