1. A computerized apparatus for determining an access relation between fields of a structure in a computer program, the computerized apparatus having a processor, the computerized apparatus comprising: a trace obtainer configured to obtain a trace associated with an execution of the computer program, the trace comprising at least one indication of access to a portion of the fields of the structure; an instance identification module configured to identify an instance of the structure accessed during the at least one indication of access; an access relation determination module configured to determine the access relation between at least two fields of the fields of the structure, wherein said access relation determination module is configured to determine the access relation based on indications of accesses to the at least two fields in the instance of the structure.