I have function which i am trying to compile and getting an error as Error: ORA-00955: name is already used by an existing object. I am really not aware of this
Error: ORA-00955: name is already used by an existing object
You probably have another object with the same name (PERFORM_CHECK).
PERFORM_CHECK
You can find it by quering user_objects:
user_objects
select * from user_objects where object_name = 'PERFORM_CHECK'
Then drop it (replace TYPE_OF_OBJECT by the type of the object from the above query):
TYPE_OF_OBJECT
drop TYPE_OF_OBJECT perform_check