1. A system comprising: machine-interpretable code configured to: select a binary program file for use in input data analysis, select an input data source having an input data format, simulate execution of the binary program file in combination with the input data source, analyze the simulated execution of the binary program file, identify multiple fields of the input data source using the simulated execution of the binary program file in combination with the input data source, determine sizes of individual fields of the input data source by applying a scoring algorithm to operand types used by the binary program file to operate on the input data source, wherein the scoring algorithm assigns at least three different score values to at least three different corresponding operand types, the at least three different score values including a first score value assigned to a first operand type, a second score value assigned to a second operand type, and a third score value assigned to a third operand type, and generate a grammar for the input data format of the input data source, the grammar identifying base types for the individual fields that are determined based on the sizes of the individual fields; and a hardware processor configured to execute the machine-interpretable code.