1. A program development apparatus, comprising: a storage device configured to store a complex intrinsic function including both an operation definition defining a program description in a source program subjected to be optimized, and an inline clause describing statements including multiple extended instructions after the optimization, the multiple extended instructions being executed by an extended module of a target processor; an analyzer configured to perform a syntax analysis of the complex intrinsic function by reading the complex intrinsic function out of the storage device, so as to detect the operation definition and the inline clause; a code generator configured to generate an object code from the source program by optimizing a program description corresponding to the operation definition in the source program into the multiple extended instructions included in the statements in the inline clause; a very long instruction word (VLIW) instruction definer configured to define a VLIW instruction including a coprocessor instruction to be executed by a coprocessor of a VLIW type included in the extended module from instructions applicable to parallel execution; and a complex intrinsic function generator configured to generate the complex intrinsic function by describing the VLIW instruction as the statements in the inline clause, and by defining the program description in the source program subjected to be optimized to the VLIW instruction as the operation definition.