1. A compilation method for translating a source program into a machine language program, using operation definition information in which an operation that corresponds to a machine language instruction for a target processor is defined in a format of a function invocation, the compilation method comprising: a parser step of analyzing, using a processor, the source program; and a code generation step of generating machine language instructions including first instructions and second instructions from the analyzed source program which includes operations defined in the operation definition information, the first instructions corresponding to the operations, the second instructions not corresponding to the operations, wherein the code generation step includes a combining sub-step of combining the first instructions and the second instructions into one machine language instruction.