Structured FORTRAN preprocessors generating optimized output

Abstract Usually a structured FORTRAN program is transformed into a standard FORTRAN program by means of a one‐pass preprocessor. In this case, several problems are caused by the many redundant continue and goto statements that a preprocessor generates. These problems include: (i) the generated FORTRAN program is not easy to read; (ii) the size of files to store the related programs becomes large; (iii) the total time increases for executing both the FORTRAN compiler and the output program itself. This paper presents a new scheme for constructing a one‐pass preprocessor that generates the optimized FORTRAN code by suppressing the redundant statements. By employing this scheme we have constructed our own preprocessors for Westran (one of the Structured FORTRAN languages) and Ratfor and measured these against the traditional preprocessors for the Westran and Ratfor languages. One of the results is as follows. The total time for users, namely ‘preprocessing time + FORTRAN compiling time’ is rather less than the traditional ones. This is due to the fact that to suppress the input/output of the redundant statements from/to files contributes to the decreasing of both preprocessing and compiling times, and this compensates completely the time‐overhead of the optimization process.