2.4 Work Faster: '-f' ===================== '-f' should only be used when assembling programs written by a (trusted) compiler. '-f' stops the assembler from doing whitespace and comment preprocessing on the input file(s) before assembling them. Preprocessing Preprocessing. _Warning:_ if you use '-f' when the files actually need to be preprocessed (if they contain comments, for example), 'as' does not work correctly.