I want to know that is there any way to find a given instruction is using an array as operand?
You could check whether the operand is a getelementptr instruction. This would indicate either an array or structure access but you could distinguish those based on the type of the accessed value. If you want to link the access to a particular array and subscript in the original source code, you might want to hack Clang to add this as metadata on the instruction (assuming your IR comes from C/C++ code). Tobias